Scientific Data DocumentationInformation For International Travelers And Health ProfessionalsDETAILED DISEASE AND PREVENTION INFORMATION Simultaneous Administration of Vaccines Simultaneous administration of most inactivated vaccines has not resulted in impaired antibody responses or increased rates of adverse reactions. Most can safely and effectively be given simultaneously at separate sites. However, when vaccines commonly associated with local side effects(such as cholera, typhoid, and plague vaccines) are given simultaneously, the side effects can be accentuated. Whenever possible, live viruses not administered on the same day should be given at least 30 days apart. Recent studies show that antibody response is decreased when yellow fever and cholera are administered within three weeks as compared to longer intervals. If under time constraints, the vaccines can be given simultaneously or anytime within the 3 week period. When considering vaccination under time restraints consider that the yellow fever vaccine and documentation are required for certain countries and is strongly recommended for those travelers to infected areas. The major benefit of the cholera vaccine is for entry into a few countries requiring a certificate. The safety and efficacy of hepatitis B vaccine, DPT, and OPV or of hepatitis B and yellow fever administered simultaneously is similar to separate administrations of the vaccines. However, in cholera and yellow fever the antibody response can be lower if administered simultaneously or within 3 weeks. There is little interaction between inactivated vaccines and Immune Globulin. Therefore, IG may be simultaneously administered at different sites with an inactivated vaccine. However, live attenuated vaccine viruses might not successfully replicate and the subsequent antibody response could be diminished when the vaccine is given with IG. In general, parenterally administered live vaccines should not be given for a least 6 weeks and preferably 3 months after IG administration. Two exceptions should be noted. If IG administration becomes necessary after a live vaccine has been given, interference may occur, and thus the vaccine may have to be repeated after at least a 3 month wait. If IG needs to be administered because of imminent exposure to disease, live virus vaccines may be administered simultaneously with IG recognizing that vaccine-induced immunity may be compromised. Administration should be at different sites. Re- immunization should occur after 3 months unless serology confirms antibody production. Note that IG does not interfere with either OPV or yellow fever vaccines.Disease Specific Menu Cholera Cholera is an acute intestinal infection caused by VIBRIO CHOLERA O-group I. The current vaccines have shown a 50% effectiveness in reducing clinical illness for 3-6 months after administration, with the greatest effectiveness in the first 2 months. It is not routinely recommended for travelers, except those traveling to any of the two countries requiring a Certificate of Vaccination against cholera. A single dose of vaccine will meet the country requirement and should be documented on a Certificate of Vaccination. Alternatively, a medical waiver signed by a physician is generally accepted by country officials. The complete vaccination schedule includes 2 doses of vaccine spaced 1 to 4 or more weeks apart. Dosages are age specific. For infants 0-6 months of age; the vaccine is not recommended, and a medical waiver must be provided for entry to countries requiring a certificate. For children 6 months to 4 years of age; .2 ml given subcutaneously or intramuscularly. For children 5 to 10 years of age; .3 ml given subcutaneously or intramuscularly. If older than 10 years of age; .5 ml given subcutaneously or intramuscularly. .2 ml intradermal dosage for travelers over age 5 may be substituted. Booster dosages are the same as the age specific dosages and are spaced every 6 months. Data indicates that simultaneous administration of cholera and yellow fever vaccines produces a less-than-normal antibody response. A 3 week minimum interval between cholera and yellow fever vaccines is recommended except in those cases where both vaccines are required and time constraints exist. Then they can be given simultaneously or any time within the three week interval. Reactions to the vaccine are: 1-2 days of pain, erythema, and induration at the site of injection; fever, malaise, and headache. Serious reactions are rare, but if experienced, re-vaccination is not advisable. No specific information on the safety of cholera vaccine and pregnancy is available, therefore vaccination should be avoided. Dengue Fever Complications Complications of dengue occur rarely in adults. Transmission Dengue viruses are transmitted by mosquitoes, who are most active during the day. These vector mosquitoes are found near human habitations and often are present indoors. Prevention There is no vaccine for dengue fever, therefore the traveler should avoid mosquito bites by remaining in well screened or air conditioned areas. Travlers are advised to use bednets, to bring aerosol insecticides to use indoors and to use mosquito repellents on skin and clothing. Symptoms The illness is a flu-like illness characterized by sudden onset, high fever, severe headaches, joint and muscle pain, and rash. The rash appears 3-4 days after the onset of fever. Travelers should alert their physician of any febrile illnesses occurring within one month after leaving an endemic area. Japanese Encephalitis Japanese Encephalitis is a viral disease transmitted by mosquitoes. Vaccination should be considered for travelers who plan long-term residence in areas experiencing epidemics, such as Japan, Korea, or countries in South East Asia, or the Indian subcontinent, especially those who will be traveling or living in rural farming areas. The vaccine is presently not available in the United States. Persons considered at risk should arrange to receive the vaccine at the country of destination. The dosing schedule is one shot per week for three weeks. Tickborne Encephalitis Tickborne encephalitis is a viral infection of the central nervous system. Found mainly in Eastern Europe and the Soviet Union, infections are caused by tick bites or by consumption of unpasteurized dairy products of cows, sheep, or goats. An effective vaccine can be obtained from Immuno, Vienna, Austria. The risk to travelers who do not visit or work in forested areas or consume unpasteurized dairy products is apparently low. Insect repellent containing N N diethymetatoluamide (deet) should be used by travelers in areas of risk. Hepatitis A Vaccine Hepatitis A, a gastrointestinally transmitted virus of high prevalence in developing countries, is prevented through use of Immune globulin (IG). For travelers a single dose of IG is recommended if travel is less than 3 months. Dosages are weight specific: for persons under 50 pounds, .5 ml. for person weighing 50 to 100 pounds, 1.0 ml. for persons larger than 100 pounds, 2.0 ml. For prolonged travel or residence in developing countries weight specific dosages are given every 5 months. for persons less than 22 pounds, .5 ml for persons weighing 22 to 50 pounds, 1.0 ml. for person weighing 50 to 100 pounds, 2.5 ml. for persons larger than 100 pounds, 5.0 ml. For traveler requiring repeated IG prophylaxis, screening for total anti-HAV antibodies before travel may eliminate the need for IG in those who are immune. IG prepared in the United States by the Cohen-Oncley procedure, the standard procedure used in U.S. manufactured preparations, carries no risk of transmitting HIV, hepatitis B, or Non A Non B hepatitis. Pregnancy is not a contraindication to using IG. Hepatitis B Vaccine The hepatitis B virus is primarily transmitted through activities which result in the exchange of blood or blood-derived fluids. Vaccination is recommended for health care workers, and long-term travelers to high Hepatitis B endemic areas. Two hepatitis vaccines are currently available in the United States. A vaccine produced from plasma of hepatitis B carriers has been available since 1982. The second vaccine uses recombinant DNA technology - a hepatitis B surface antigen is inserted into bakers yeast. The second vaccine became available in 1987. Both give comparable immunogenicity and efficacy when given in the recommended dosages. The primary adult vaccination schedule consists of 3 intramuscular doses of either 20ug of plasma-derived vaccine, or 10ug of the recombinant DNA vaccine. The second dose should follow one month later, with the final dose 6 months after the first. Children may receive either vaccine at a 50% adult dosage level spaced on the same schedule. Optimal protection is reached after the third dosage. Some protection is provided by one or two doses, therefore the vaccination process should be initiated, even if it can not be completed before departure. The duration of protection and the need for booster doses has not been determined. The optimum site of injection in adults is the deltoid muscle, vaccination in the buttocks results in a poorer antibody response. The major side-effects with the hepatitis B vaccine have been soreness and redness at the site of injection. Serious adverse reaction have rarely been reported. The production process for the plasma vaccine has been shown to inactivate all classes of viruses found in blood including HIV. Pregnancy is not a contraindication to the use of the vaccine. Specific data is not available on the safety of the vaccine for the developing fetus, but because it contains only non-infectious HBsAG particles, administration of the vaccine to pregnant women is not considered to constitute a risk to the fetus. Malaria Malaria in humans is caused by one of four protozoan species of the genus Plasmodium: P. falciparum, P. vivax, P. ovale, and P. malariae. All are transmitted by the bite of an infected female Anopheles mosquito. Occasionally transmission occurs by blood transfusion or congenitally from mother to fetus. The disease is characterized by fever and flu-like symptoms including chills, headache, myalgias, and malaise, which may occur at intervals. Malaria may be associated with anemia and jaundice, and P. falciparum infections may cause kidney failure, coma, and death. Deaths due to malaria are preventable. Information on malaria risk in specific countries (pp. 15-60), is derived from various sources including the World Health Organization. While this is the most accurate information available at the time of publication, factors which can vary from year to year, such as local weather conditions, mosquito vector density, and prevalence of infection, can have a marked effect on local malaria transmission patterns. Risk of Acquiring Malaria Malaria transmission occurs in large areas of Central and South America, Hispaniola, sub-Saharan Africa, the Indian Subcontinent, Southeast Asia, the Middle East, and Oceania. The estimated risk of acquiring malaria varies markedly from area to area. This variability is a function of the intensity of transmission in both urban and rural areas within the various regions, and also depends on itinerary and time and type of travel. During 1980-1989, 1,834 cases of P. falciparum among U.S. civilians were reported to the CDC. Of these, 1,491 (81%) were acquired in sub-Saharan Africa, 136 (7%) were acquired in Asia; 105 (6%), were acquired in the Caribbean and South America, and 103 (6%), in other parts of the world. Of the 41 fatal infections, 31 were acquired in sub-Saharan Africa. Thus, most imported malaria among U.S. travelers was acquired in sub-Saharan Africa, even though only an estimated 90,000 Americans travel to sub-Saharan Africa each year, versus an estimated 900,000 American travel to malarious areas of Asia and South America each year. This disparity in the risk of acquiring malaria reflects the fact that travelers to Africa are at risk in most rural and many urban areas, and moreover, tend to spend considerable amounts of time, including evening and nighttime hours, in rural areas where malaria risk is highest. Travelers to Asia and South America, however, spend most of their time in urban or resort areas where there is limited, if any, risk of exposure, and travel to rural areas mainly during daytime hours when there is limited risk of infection. Estimating the risk of infection for different categories of travelers is difficult, even if persons travel or reside temporarily in the same general areas within a country. For example, tourists staying in air-conditioned hotels may be at lower risk than backpackers or adventure travelers. Similarly, longer-term residents living in screened and air-conditioned housing are less likely to be exposed than are missionaries or Peace Corps volunteers. Checklist for Travelers to Malarious Areas The following is a checklist of key issues to be considered in advising travelers. Risk of malaria Travelers should be informed about the risk of malaria infection and the presence of drug-resistant P. falciparum malaria in their areas of destination. Anti-mosquito measures Travelers should know how to protect themselves against mosquito bites. Chemoprophylaxis Travelers should be: -- Questioned about drug allergies and other contraindications for use of drug to prevent malaria. -- Advised which drug to use for prophylaxiss, and, if chloroquine used, whether Fansidar should be carried for presumptive self-treatment. -- Advised to use prophylaxis continuously while in malaria- endemic area and for four weeks after leaving such areas. -- Informed that antimalaria drugs can cause side effects; are serious, medical help should be sought promptly and use of the drug discontinued. -- Warned that they may acquire malaria even if they use malaria chemoprophylaxis. In case of illness Travelers should be: -- Informed that symptoms of malaria may be mild, and that may be mild, and that they should suspect malaria if they experience unexplained fever or other symptoms such as persistent headaches, muscular aching and weakness, vomiting, or diarrhea. -- Informed that malaria may be fatal if treatment is de- layed. Medical help should be sought promptly if malaria is suspected, and a blood sample should be taken and examined for malaria parasites on one or more occasions. -- Reminded that self-treatment should be taken only if prompt medical advice should still be sought as soon as possible after self-treatment. Special categories -- Pregnant women and young children require special attention because they cannot use some drugs (mefloquine and doxycycline). -- Concurrent use of other drugs, e.g. beta-blockers, may be a contraindication for use of mefloquine. (Adapted from International Travel and Health, World Health Organization, Geneva, 1991) Drug Resistance Resistance of P. falciparum to chloroquine has been confirmed or is probable in all countries with P. falciparum malaria except the Dominican Republic, Haiti, Central America west of the Panama Canal, Egypt, and most countries in the Middle East. In addition, resistance to both chloroquine and FansidarR* is widespread in Thailand, Burma, and Cambodia, and the Amazon basin area of South America, and resistance has also been reported in sub-Saharan Africa. *Use of names is for identification only and does not imply endorsement by the Public Health Service or the U.S. Department of Health and Human Services. General Advice for Travelers to Malaria-Endemic Areas All travelers to malarious areas of the world are advised to use an appropriate drug regimen and personal protection measures to prevent malaria; however, travelers should be informed that regardless of methods employed, malaria still may be contracted. Malaria symptoms can develop as early as 8 days after initial exposure in a malaria-endemic area and as late several months after departure from a malarious area, after chemoprophylaxis has been terminated. Travelers should understand that malaria can be treated effectively early in the course of the disease, but that delay of appropriate therapy can have serious or even fatal consequences. Individuals who have the symptoms of malaria should seek prompt medical evaluation including thick and thin malaria smears as soon as possible. Personal Protection Measures Because of the nocturnal feeding habits of Anopheles mosquitoes, malaria transmission occurs primarily between dusk and dawn. Travelers should take protective measures to reduce contact with mosquitoes especially during these hours. Such measures include remaining in well-screened areas, using mosquito nets, and wearing clothes that cover most of the body. Additionally, travelers should be advised to purchase insect repellent before travel for use on exposed skin. The most effective repellents contain N,N diethylmetatoluamide (DEET), an ingredient in many commercially available insect repellents. The actual concentration of DEET varies among repellents ranging up to 95 percent. rarely children exposed to DEET have had toxic encephalopathy. The possibility of adverse reactions to DEET will be minimized if the following precautions are taken: apply repellent sparingly only to exposed skin or clothing; avoid applying high-concentration products to the skin; do not inhale or ingest repellents or get them into the eyes; avoid applying repellents to portions of children's hands that are likely to have contact with eyes or mouth; never use repellents on wounds or irritated skin; wash repellent-treated skin after coming indoors; if suspected reaction to insect repellent occurs, wash treated skin and seek medical attention. Travelers should use a pyrethrum-containing flying-insect spray in living and sleeping areas during evening and nighttime hours. Permethrin (PermanoneR) may be sprayed on clothing for protection against mosquitoes. (Insert Camera-Ready Copy of Malaria map) Chemoprophylaxis In choosing an appropriate chemoprophylactic regimen before travel, persons should consider several factors. The travel itinerary should be reviewed in detail and compared with the information on areas of risk within a given country to determine whether the traveler will actually be at risk of acquiring malaria. It should be determined whether the traveler will be at risk of acquiring chloroquine-resistant P. falciparum malaria. In addition, it should be established whether the traveler has previously experienced an allergic or other reaction to the antimalarial drug of choice and whether medical care will be readily accessible during travel. Malaria chemoprophylaxis should preferably begin 1-2 weeks before travel to malarious areas (except for doxycycline, which can begin 1-2 days before). In addition to assuring adequate blood levels of the drug, this allows any potential side-effects to be evaluated and treated by the traveler's physician before departure. Chemoprophylaxis should continue during travel in the malarious areas and for 4 weeks after leaving the malarious areas. Chemoprophylactic Regimens Regimen A: For travel to areas of risk where chloroquine- resistant P. falciparum has NOT been reported, once-weekly use of chloroquine alone is recommended. Chloroquine is usually well tolerated. The few people who experience uncomfortable side-effects may tolerate the drug better by taking it with meals, or in divided, twice-weekly doses. As an alternative, the related compound hydroxychloroquine may be better tolerated. Chloroquine prophylaxis can begin 1-2 weeks before travel to malarious areas. It should be continued weekly during travel in malarious areas and for 4 weeks after a person leaves such areas. (See table 11a for recommended dosages.) Regimen B: For travel to areas of risk where chloroquine- resistant P. falciparum exists, use of mefloquine alone is recommended. Mefloquine prophylaxis should begin 1-2 weeks before travel to malarious areas. It should be continued weekly during travel in malarious areas and for 4 weeks after a person leaves such areeas. (See Table 11a for recommended dosages.) Note: In some foreign countries a fixed combination of mefloquine and Fansidar is marketed under the name FansimefR. Fansimef should not be confused with mefloquine, and it is not recommended for prohylaxis of malaria. Alternative to Mefloquine Travlers to areas of risk where drug-resistant P. falciparum is endemic for whom mefloquine is contraindicated may elect to use an alternative regimen, as follows: Doxycycline alone taken daily is an alternative regimen for short-term travel who are intolerant of mefloquine or for whom the drug is contraindicated. Travelers who use doxycycline should be cautioned about the possible side effects as described in the section on adverse reactions. Doxycycline prophylaxis can begin 1-2 days before to travel to malarious areas. It should be continued daily during travel in malarious areas and for 4 weeks after the traveler leaves such areas. (See table 11a for recommended dosages.) Chloroquine alone is taken weekly is recommended for travelers who can not use mefloquine or doxycycline, especially pregnant women and children under 15 kg. Proguanil (PaludrineR) is not available commercially in the United States. Limited data suggest that it may be effective in East Africa, but not in Thailand, Papua New Guinea, and West Africa. If travelers use proguanil, it should be taken as a daily 200 mg. dose (adult) in combination with weekly Chloroquine. Self-treatment Travelers who elect to use chloroquine (except those with histories of sulfonamide intolerance) should be given a treatment dose of FansidarR promptly in the event they have a febrile illness during their travel when professional medical care is not readily available, and they should be aware that this self- treatment of a possible malarial infection is only a temporary measure and that prompt medical evaluation is imperative. They should continue their weekly chloroquine prophylaxis after presumptive treatment with FansidarR. (See Table 11a for recommended dosages for prophylaxis and Table 11b for presumptive treatment with Fanidar.) Mefloquine should not be used for self-treatment because of the frequency of serious side effects (e.g. hallucinations, convulsions) which has been associated with therapeutic dosages of mefloquine. Primaquine: Prevention of Relapses of Plasmodium vivax and Plasmodium ovale. P. vivax and P. ovale parasites can persist in the liver and cause relapses for as long as 4 years after routine chemoprophylaxis is discontinued. Travelers to malarious areas should be alerted to this risk; and if they develop malaria symptoms after they leave a malarious area they should report their travel history and the possibility of malaria to a physician as soon as possible. Primaquine decreases the risk of relapses by acting against the liver stages of P. vivax and P. ovale. Primaquine is administered after the traveler has left an endemic area, usually during the last 2 weeks of the period of prophylaxis after exposure in an endemic area has ended. Since most malarious areas of the world (except Haiti) have at least one species of relapsing malaria, travelers to these areas have some risk of acquiring either P. vivax or P. ovale. Prophylaxis with primaquinem is generally indicated only for persons who have had prolonged exposure in malaria-endemic areas, e.g., missionaries and Peace Corps volunteers. Although the actual risk to traveler with less intense exposure is difficult to define, with the exception of individuals deficient in glucose-6-phosphate dehydrogenase (G6PD) (see discussion of adverse reactions), most people can tolerate the standard regimen of primaquine. (See Table 11a for recommended dosages.) Adverse Reactions and Contraindications to Antimalarials The frequent or serious side effects of recommended antimalarials are discussed below. In addition, physicians should review the prescribing information in standard pharmaceutical reference texts and in the manufacturers' package inserts. Chloroquine and hydroxychloroquine rarely cause serious adverse reactions when taken at prophylactic doses for malaria. Minor side-effects may occur, such as gastrointestinal disturbance, headache, dizziness, blurred vision, and pruritus occur, but generally these effects do not require discontinuance the drug. High doses of chloroquine, such as that used to treat rheumatoid arthritis, has been associated with retinopathy, but this serious side-effect has not been associated with routine weekly malaria prophylaxis. Chloroquine and related compounds have been reported to exacerbate psoriasis. Chloroquine may interfere with the antibody response to human diploid cell rabies vaccine when it is administrated intradermally. Mefloquine has been asociated rarely with serious adverse reactions (e.g., hallucination, convulsions) at prophylactic dosage, but these reactions are more frequent with the higher dosages used in treatment. Minor side effects observed with prohylacitic doses, such as gastrointestinal disturbance and dizziness, tend to be transient and self-limited. Mefloquine is not recommended for use by travelers with a know hypersensitivity to mefloquine; children < 15kg. (30 lbs.); pregnant women; travelers using beta blockers; travelers involved in tasks requiring fine coordination and spatial discrimination, such as airline pilots; and travelers with a history of epilepsy or psychiatric disorder. All studies to date confirm that mefloquine is well tolerated when used for prophylaxis; however, monitoring the occurrence of severe adverse reactions is important because such reactions are possible. Users of mefloquine prophylaxis, who experience seriouss adverse reactions should consult their physician, and the reactions should be reported to the Malaria Branch, CDC, telephone (404) 488-4046. Travelers who use doxycycline should be aware of the possibility of photosensitivity, usually manifested as an exaggerated sunburn reaction. The risk of such a reaction can be minimized by avoiding prolonged, direct exposure to the sun; using sunscreens that absorb long-wave ultraviolet (UVA) radiation; and taking the drug in the evening. In addition, doxycycline use is associated with an increased frequency of monilial vaginitis. Gastrointestinal side effects (nausea or vomiting ) may be minimized by taking the drug with a meal. Tetracyclines are contraindicated in pregnancy and in children < 8 years of age. The use of FansidarR is contraindicated in persons with histories of sulfonamide intolerance and in infants under 2 months of age. Proguanil rarely causes adverse reactions at prophylactic dosage. Reported side effects include nausea, vomiting, mouth ulcers, and hair loss. Primaquine may cause severe hemolysis in G6PD deficient individuals. Before using primaquine, G6PD deficiency should be ruled out by appropriate laboratory testing. Chemoprophylaxis for Children Children of any age can contract malaria. Consequently, the indications for prophylaxis are identical to those described for adults. Mefloquine is not indicated for children <15 kg. (30 lbs.). Doxycycline is contraindicated in children <8 years of age. (See recommended dosages in Table 11a.) Chloroquine phosphate is manufactured in the United States in tablet form only, and tastes quite bitter. Pediatric doses should be calculated carefully according to body weight. Pharmacists can pulverize tablets and prepare gelatin capsules with calculated pediatric doses. Mixing the powder in food or drink may facilitate the weekly administration of chloroquine to children. Alternatively, chloroquine in suspension is widely available overseas. Parents should calculate the volume to be administered, because the concentration of chloroquine base varies in different suspensions. OVERDOSE OF ANTIMALARIAL DRUGS CAN BE FATAL. THE MEDICATION SHOULD BE STORED IN CHILDPROOF CONTAINERS OUT OF THE REACH OF CHILDREN. Prophylaxis During Pregnancy Malaria infection in pregnant women may be more severe than in non-pregnant women. In addition, there may be increased risk of adverse pregnancy outcomes including prematurity, abortion, and stillbirth. For these reasons, and because chloroquine has not been found to have any harmful effects on the fetus when used in the recommended doses for malaria prophylaxis, pregnancy is not a contraindication to malaria prophylaxis with chloroquine or hydroxychloroquine. However, because no chemoprophylactic regimen is completely effective in areas with chloroquine-resistant P. falciparum, women who are pregnant or likely to become so should avoid travel to such areas. Mefloquine should not be used during pregnancy. Women of childbearing potential who are taking mefloquine for malaria prophylaxis should take reliable contraceptive precautions for the duration of prophylaxis and for two months after the last dose of mefloquine. Doxycycline is generally contraindicated for malaria prophylaxis during pregnancy. Adverse effects of tetracyclines on the fetus include discoloration and dysplasia of the teeth and inhibition of bone growth. In pregnancy therefore, tetracyclines would be indicated only if required to treat life threatening infections due to multidrug- resistant P. falciparum. Proguanil has been widely used for several decades and no adverse effects on pregnancy or fetus have been established Primaquine should not be used during pregnancy because the drug may be passed transplacentally to a G6PD-deficient fetus, and cause hemolytic anemia in-utero. Whenever radical cure or terminal prophylaxis with primaquine is indicated during pregnancy, chloroquine should be given once a week until delivery, at which time the decision to give primaquine may be made. Prophylaxis While Breast-feeding Very small amounts of antimalarial drugs are secreted in the breast milk of lactating women. The amount of drug transferred is not thought to be harmful to nursing infant; however, more information is needed. Because the quantity of antimalarials transferred in breast milk is insufficient to provide adequate protection against malaria, infants who require chemoprophylaxis should receive the recommended dosages of antimalarials listed in Table 11a. Malaria Hotline Detailed recommendations for the prevention of malaria are available 24 hours a day by calling the CDC Malaria Hotline at (404) 332-4555. Meningococcal Disease Vaccination for meningococcal disease is recommended for travelers going to the sub-sahara Africa during the dry season. The countries of highest risk are Mali, Niger, Chad, Sudan, Ethiopia, Bukina Faso, Benin, Nigeria, and the northern parts of Somalia. In addition CDC currently recommends the vaccine for all travelers to Saudi Arabia, Nepal, and the Delhi region of India. Serogroup A is the most common cause of the epidemics. Meningococcal vaccines are chemically defined antigens consisting of purified bacterial capsular polysaccharide, each producing serogroup-specific immunity. Only one formulation of vaccine is currently available in the United States - quadrivalent A/C/Y/W-135 called Menomune is distributed through Connaught. No vaccine is available for Serogroup B. A one dose subcutaneous injection in the volume specified by the manufacturer provides immunity for approximately 3 years. Vaccine response rates vary with serogroups and so may be less than effective. Children vaccinated before the age of 4 should be re-vaccinated after 2 to 3 years if at high risk. Follow the manufacturer's instructions for proper dosing. Reaction to the vaccine are infrequent and mild, consisting principally of localized erythema that last for 1-2 days. Up to 2% of young children develop a fever transiently after vaccination. The safety of meningococcal vaccine and pregnancy has not been established. It is prudent to avoid the use of the vaccine with pregnant women unless there is substantial risk. Plague Vaccination against plague is not required by any country as a condition for entry. Neither is it recommended except for those who are at particularly high risk of exposure because of research or field exposure. A 3 dose primary series spaced over about 8 weeks and an additional booster dose six months later are available. See package insert for dosing information. The true protection provided by the vaccine is not known due to the limited use. Reactions Mild pain, erythema, and induration at the injection site occur frequently. With repeated doses, fever, headache, and malaise are common and more severe. Sterile abscesses occur rarely, but no fatalities or disabling complications have been reported. Contraindications In pregnancy only selected vaccinations of exposed persons would be recommended. Rabies Requirements Pre-exposure vaccination is not indicated for travelers to large cities or a rabies free country. Transmission Rabies is almost always transmitted by bites which introduce the virus into the wound. Although dogs are the main reservoir of the disease, all warm- blooded animal bites should be suspect. Prevention Do not handle any animals! Any animal bite should receive prompt attention. When wounds are thoroughly cleaned with large amounts of soap and water, the risk of rabies infection is reduced. Exposed individuals should receive prompt medical attention and advice on post-exposure preventive treatment. Upon returning to the U.S. exposed individuals should contact their local physician or state health department. Schistosomiasis Transmission Schistosomiasis is developed after the larvae of a flat worm has penetrated the skin. The larvae are released into the water from infected snails who are the worms host. The larvae are capable of penetrating unbroken skin. Two ingredients are necessary, fresh water and snails. Brackish water or areas of poor sanitation are a contributing factor. Water treated with chlorine or iodine is virtually safe, and salt water poses no risk. Prevention The traveler cannot distinguish between infested and non-infested water. Therefore, swimming in fresh water in rural area should be avoided. Bath water should either be heated to 50 degrees C (122 degrees F) for five min- utes or treated with chlorine or iodine as done for drinking water. Treatment If exposed to suspected water, immediate and vigorous towel drying or appli- cation of rubbing alcohol to the exposed areas will reduce the rish of infection. Screening procedures are available for those who suspect infection, and schistosomiasis is treatable with drugs. Typhoid Fever Transmission Salmonella typhi, the organism which causes typhoid fever, is transmitted through contaminated food and water. Prevention By drinking only bottled or boiled water and eating only cooked food, a traveler lowers the risk of infection. Currently available vaccines have been shown to protect 70- 90% of the recipients. Therefore, even vaccinated travelers should be cautious in selecting their food and water. The primary series of vaccine consists of two shots, spaced at least 4 weeks apart. A booster dose given every 3 years provides continued protection for repeated exposure. If there is insufficient time for two doses a month apart, an accelerated schedule of three shots a week apart may be administered. It is recognized that the accelerated schedule is less effective. A primary series need never be repeated. Treatment Symptoms of typhoid include fever, headaches, malaise, anorexia, and consti- pation more often than diarrhea. Seek medical assistance immediately for appropriate antibiotic treatment. Yellow Fever Yellow fever is a viral disease. Vaccines are available only through approved yellow fever vaccination centers designated by state health departments. Call your state and local health departments to find the center closest to you. One dose of .5 ml of vaccine may be administered to anyone over 9 months of age. A booster of equal amount may be given every 10 years. Infants under 4 months must not be immunized. Persons with a hypersensitivity to eggs should not be given the vaccine. Persons able to eat eggs or egg products can receive the vaccine. Efforts should be made to obtain a medical waiver for persons hypersensitive to the vaccine. A physicians letter clearly stating the contraindication to the vaccine, has been acceptable to some governments. It should be written on letterhead stationary and bear the stamp used by a health department or official immunization center to validate the International Certificate of Vaccination. Also check embassies or consulates for waiver of requirements information. Reactions occur in less than 5% of those vaccinated for yellow fever. They are generally mild, for example, headaches, low-grade fevers, myalgia, or other minor symptoms. Patients with immunosuppression, including AIDS, leukemia, lymphoma, generalized malignancy, etc. or those patients using corticosteroids, alkylating drugs, antimetabolites, or radiation should not receive the vaccine. Simultaneous Administration of yellow fever vaccine and other live virus vaccines have not caused inhibition of the yellow fever vaccine. If live viruses are not given concurrently, 4 weeks should be allowed to lapse between sequential vaccinations. Simultaneous administration of cholera and yellow fever vaccines has produced a lower-than-normal antibody response to both vaccines. There is no data of interference between yellow fever and typhoid, paratyphoid, typhus, plague, rabies, or Japanese encephalitis. Pregnancy is not a contraindication to yellow fever vaccine. However, specific information is not available concerning the adverse effects of yellow fever vaccine and the developing fetus. If possible avoid vaccination.Vaccinations and Pregnancy Live Virus Vaccines Live attenuated-virus vaccines are not generally given to pregnant women or to those likely to become pregnant within 3 months of receiving the vaccine. For the MMR vaccine, pregnancy is a contraindication. Only with a substantial risk of exposure to natural infection of the disease should either yellow fever or OPV be given to pregnant women . If given during pregnancy, waiting until the second or third trimester minimizes concerns over teratogenicity. The risk of teratogenicity from live rubella vaccine is small, with no evidence of congenital rubella syndrome in infants born to mothers who inadvertently were vaccinated during pregnancy. For poliomyelitis OPV is recommended over IPV when immediate protection is needed. MMR and OPV vaccines can safely be administered to children of pregnant women in spite of viral shedding. To date the evidence shows no risk to the developing fetus. Inactivated Vaccines There is no convincing evidence of risk to fetus from inactivated viral or bacterial vaccines, or toxoids administered to pregnant women. These include: hep B, rabies, cholera, typhoid, plague, meningococcal, pneumococcal, and the adult formulation of the Td toxoid. If immunization is considered, the risk and probability of contracting the disease should be weighed against benefits and complication from administering the vaccine. Unimmunized pregnant women who may deliver under non-hygienic circumstances should receive two properly spaced doses of Td, preferably during the last two trimesters. Incompletely immunized women should complete the three dose series. Those immunized more than 10 years ago should receive a booster dosage. For IG there is no known risk to the fetus from passive immunization of pregnant women. Vaccinations of Children Less Than 2 Years of Age The vaccine information in this section is presented in alphabetical order by disease. Cholera vaccine is of questionable benefit to travelers of any age. It is not recommended in children less than 6 months old. Breast-feeding is protective against cholera. For other infants careful preparation of formula and food from safe water and foodstuffs should protect non-breast-fed infants. Diphtheria, tetanus, and pertussis is endemic in developing countries, and therefore may put the infant at greater risk than in the U.S. Optimum protection in the first year of life is achieved with three doses of DTP administered normally. Infants traveling should have received 3 doses of DTP, the first dose at 6-8 weeks of age, and the next two doses at 4-8 week intervals. A forth dose, generally 6-12 months after the third dose maintains protection. For infants at imminent risk, reducing the interval between the third and forth doses of the primary series to six months may be considered. One dosage by its self affords little protection, while two doses provide some protection. Parents must note that less than the 3 recommended doses of DTP puts a child at greater risk of infection. If traveling for extensive periods, travelers may wish to receive the remaining doses of the vaccine at the recommended intervals while abroad. Hepatitis B vaccine should be considered for infants and children who will live 6 months or more in smaller cities and rural areas of developing countries where hep B is endemic, and who will be in contact with the local population. This is especially true when the local children have open skin lesions such as impetigo, scabies, scratched insect bites, or when any risk of exposure to blood from the local population occurs. Immune globulin is recommended for infants and children traveling outside the usual tourist routes if they will be eating food and water in settings of questionable sanitation. MMR vaccine should be administered to all children 15 months of age or older. For earlier departure to areas of high risk, vaccines may be administered as follows: Children 12-14 months of age may receive MMR before their departure without need for re-vaccination; at ages 6-11 months a single dose of single measles antigen vaccine (without mumps and rubella) may be given before departure, with re-vaccination of the MMR vaccine coming at 15 months, and if required as early as 12 months. Infant less than 6 months of age are protected by maternally derived antibodies. The risk of serious disease from Mumps and rubella is so small that no vaccination is required before 12 months. For Meningococcal vaccine effectiveness of the vaccine in children is dependent upon the child's age when the vaccine is administered. Protection against certain strains of the bacteria may not be effective in children vaccinated between 3 months and 2 years. Vaccination before 3 months of age has little effectiveness against the disease. The vaccine may be safely given to infants with the understanding that it may be less effective than in adults. OPV is the vaccine of choice for all infants and children if there are no contraindications to the vaccine. Inactivated poliovirus vaccine is also available. Children traveling to endemic areas should receive at least 3 doses of OPV at intervals of at least 6-8 weeks. A forth dose may be given if at least 6 weeks have elapsed since the third dose. If travel is to occur before a child is 6 weeks old, a dose of OPV should be administered prior to travel. The dose of OPV given before 6 weeks of age should not be counted as part of the primary series. Children traveling to endemic areas should complete the 3 dose primary series abroad with doses at 4 week intervals. Children with only partial immunity should complete the primary series if they remain in a high risk area. For plague vaccine children under 1 year of age, dose 1 is .2 ml; dose 2 is .04 ml and spaced 4 or more weeks later. A third dose of .04 ml follows the second by 3-6 months. Give 2 booster doses of .02-.04 ml 6 months apart, then one booster every 1-2 years. For children between 1 and 4 years of age, dose 1 is .4 ml; dose two is .08 ml spaced 4 weeks later. A third dose of .08 ml follows the second by 3-6 months. Give 2 booster doses of .04-.08 ml 6 months apart, then one booster every 1-2 years. For typhoid fever breast feeding is likely to protect infants. Careful preparation of formula and food from safe water should protect non-breast-fed infants. Typhoid fever vaccine is recommended for children older than 2 years of age traveling to areas where there is questionable sanitation. Yellow Fever vaccine should not be administered to any infant under 4 months of age. Immunization of children 4-6 months old should be considered only under very unusual circumstances. (Consult CDC at 303-221-6400.) It may be administered to infants 6-9 months if traveling to areas of risk and when a high level of protection against mosquito bites is not possible. Infants 9 months or older should be vaccinated if they are traveling to or living in areas of South America or Africa where yellow fever infection is officially reported. General Vaccinations-Recommended for Adult Travelers All adult travelers should have their polio and tetanus immunizations up to date. Tetanus should be boosted every ten years. If the traveler completed in the past a primary polio series of either OPV or IPV, they should receive one additional dose of OPV or IPV before most travel. This is due to the higher risk of exposure to "wild" polio virus found abroad. This is strongly advised for travelers to less developed countries. Persons who are unvaccinated or who do not know their polio vaccination history should take 2 shots of inactivated polio virus vaccine at least a month apart for protection prior to travel. If less than four weeks are available before protection is needed a single dose of OPV or IPV is recommended. There is a slightly higher rate of vaccine induced polio in adults than in children following OPV. This is most often associated with persons who either have no prior immunization or are unknowingly immunodeficient. Persons who receive less than a full primary course of OPV or IPV should complete the required doses for the primary series regardless of the time interval since the last dose. The vaccine should be of the type previously received. No serious side effects for IPV have been documented, however since IPV contains trace amounts of streptomycin and neomycin, person with a history of anaphylactic reaction following administration of those antibiotics should not receive IPV. Travelers should be immune to measles. Most people born before 1957 have natural immunity. Those born after 1957 should be immune either by documented history of disease or history of vaccination. Healthy travelers over 65 may benefit from the flu shot taken during the flu season. Food and Water General Risks Contaminated food and drink are the major sources of stomach or intestinal illness while traveling. Intestinal problems due to poor sanitation are found in far greater numbers outside the United States. The information under food and water precautions can help prevent infection to many of these diseases. Water General In areas of poor sanitation only the following beverages may be safe to drink: - Boiled or bottled water - Hot beverages made with boiled water, such as coffee or tea. - Canned or bottled carbonated beverages. - Beer and Wine. Ice and drinking containers should also be considered as contaminated. It is safer to drink from a can or bottle of beverage than to drink from a questionable container. Water on the surface of beverage container may also be contaminated. Therefore beverage containers should be dry and the area to contact the mouth should be wiped clean. Where water is contaminated, the traveler should avoid brushing their teeth with tap water. Treatment of Water Boiling is by far the most reliable method to make water safe to drink. From a vigorous boil allow the water to cool to room temperature - do not add ice. At higher altitudes allow water to boil for a few minutes or use chemical disinfectants. Adding a pinch of salt or pouring water from one container to another will improve the taste. Chemical disinfection can be achieved with either iodine or chlorine, with iodine providing greater disinfection in a wider set of circumstances. For disinfection with iodine use either tincture of iodine or tetraglycine hydroperiodide tablets, such as, Globaline, Potable-Aqua, and others. These disinfectants can be found in sporting good stores and pharmacies. Read and follow the manufacturer's instructions. If the water is cloudy then strain it through a clean cloth, and double the number of disinfectant tablets added. If the water is very cold, either warm it or allow increased time for disinfectant to work. CDC makes no recommendation as to the use of any of the portable filters on the consumer market due to the lack of independently verified results to their efficacy. As a last resort, water that is uncomfortably hot to touch may be safe for drinking and brushing teeth after it is allowed to cool to room temperature. Food General To avoid illness food should be selected with care. All raw food is subject to contamination, particularly in areas of poor sanitation. Questionable foods are: salads, uncooked vegetables and fruit, unpasteurized milk and milk products, raw meat, or shellfish. If you peal fruit yourself it is generally safe. Food that has been cooked and is still hot is generally safe. For infants less than 6 months of age, breast feed or give powdered commercial formula prepared with boiling water. Some normally edible fish are not safe even when cooked. Tropical reef fish, red snapper, amberjack, grouper, sea bass, and barracuda can become toxic at unpredictable times. Highest risk areas include the islands of the West Indies, Pacific and Indian Oceans. Travelers Diarrhea Travelers diarrhea is a syndrome characterized by a twofold or greater increase in the frequency of unformed bowel movements. Symptoms include cramps, nausea, bloating, fever, urgency, and malaise. Episodes begin abruptly with increased frequency when traveling to areas of higher risk, such as, the developing countries of Africa, the Middle East, Asia, or Latin America. Risk of infection increases by type of eating establishment - from lower risk in private homes, to high risk for food from street vendors. TD is slightly more common in young adults than in older people, with no difference between males and females. Td is usually acquired through ingestion of fecally contaminated food and water. TD lasts from 3 to 7 days but sometimes longer. Rarely is it life threatening. Prevention There are four possible approaches to preventing TD - meticulous attention to food and beverage preparation, immunization, use of nonantimicrobial medication, and preventive antibiotic drugs. CDC does not recommend the use of antibiotics or other medications as they can cause additional problems themselves. Instead, careful selection of food and water is encouraged. If illness occurs the use of such products as Lomotil or Immodium should be sufficient for most travelers. It is not to be used by anyone with a high fever or blood in their stools. Treatment If symptoms do not resolve after using these preparations, antimicrobial drugs such as doxycycline, and trimethoprim/sulfamethoxazole (TMP/SMX for short) can shorten the length of sickness. Consult your physician prescription and dose schedules. Oral fluids should be administered to suffers of diarrhea. Fruit juices suitable for drinking, soft drinks preferably without caffeine, and salted crackers are advised. Avoid dairy products, and all beverages that contain water of questionable quality. It is important for the traveler to consult a physician about treatment of diarrhea in children and infants, because many of the drugs mentioned are not recommended for them. The greatest risk for children and especially infants is dehydration. Prevention of dehydration through administration of soups, thin porridges, and other safe beverages is advised. If bloody diarrhea, moderate dehydration, fever in excess of 102 F degrees, or persistent vomiting occurs seek immediate medical help. As with all diseases it is best to consult a physician rather than attempt self-medication, especially for pregnant women and children. If diarrhea is severe or does not resolve within a few days, or a fever occurs with shaking, or if there is dehydration, travelers should seek medical help.PUBLISHED MATERIALS CDC is authorized to distribute at no cost the book Health Information for International Travel as well as other related materials to physicians, public health care workers, travel agencies, and units of the Federal Government. International Certificate of Vaccination may be ordered for officially designated vaccination centers by calling the superintendent of documents at 202-783-3238. The cost is $2.00 each or $14.00 per 100. The form number is PHS-731 #017-001-004405. The address of the Superintendent of Documents is U.S. Government Printing Office, Washington, DC 20402. All previous editions of this document are valid and may be used without problem. If you do not qualify to receive our publications free, you can purchase the pamphlet Health Information for International Travel. You may purchase a current copy of the Health Information for International Travel document, H.H.S. Publication number (CDC) 88-8280, from the Superintendent of documents, U.S. Government Printing Office, Washington, D.C. 20402, telephone number 202-783-3238. Please include a check or money order for $4.75.AIDS INFORMATION Acquired Immunodeficiency Syndrome or AIDS is the severest manifestation of the human immunodeficiency virus (HIV). The incubation period for AIDS may be long, up to several years. Currently there is no vaccine, and no cure for AIDS. AIDS is found on every continent, with over 125 countries reporting, but actual cases far exceeding reported information. With the global distribution of HIV, risk of infection is behaviorally based rather than geographically related. The international traveller should know about the transmission and prevention of HIV infection, as well as the complications of travel for persons with HIV infection. HIV infection is preventable, as its transmission is not through casual contact, air, food, or water routes; contact with inanimate objects; through mosquitoes or other arthropod vectors. The use of any means of public travel by people infected with HIV does not pose a risk of HIV infection to other passengers. HIV is transmitted through sexual intercourse - heterosexual or homosexual with an infected person; use of unsterilized syringes and needles, (e.g. drug use, acupuncture, or tattooing); through blood or blood components; and perinatally from an infected pregnant mother. Travelers should avoid sexual encounters with any one thought to be infected with HIV or whose HIV infection status is unknown. Avoid sexual encounters with intravenous drug users, people with multiple sexual partners, including prostitutes either male or female. Condoms may decrease but not eliminate the risk of transmission. Do not use drugs intravenously or share needles for any reason. Needles must be sterile, preferably disposable, and prepackaged in a sealed, single unit container. Diabetics or other people requiring frequent injections should carry a supply of syringes and needles to last the entire stay abroad. Unlike the US, Japan, Canada, Australia, and western European countries where mandatory testing procedures have greatly reduced the risk of HIV infection, blood and blood products available in less-developed countries may not be formally tested for HIV contamination. Locally produced blood clotting factor concentrates and blood from the native population should not be used unless tested by appropriately-trained technicians using reliable tests. US produced IG that follows the Food and Drug Administrations procedures is safe from HIV. Recently, several countries have established serological screening of incoming passengers to detect either AIDS or HIV antibodies. Travelers testing positive are refused entry. With one or two exceptions these tests are only being done on travelers staying in a country greater than 3 months. The testing requirements for individual countries can be obtained by calling the appropriate Consulate office in Washington, D.C.
This page last reviewed: Thursday, January 28, 2016
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