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Medical Advice for International Travelers

2001; Elsevier BV; Volume: 76; Issue: 8 Linguagem: Inglês

10.1016/s0025-6196(11)63229-1

1942-5546

Abinash Virk,

Zoonotic diseases and public health

Each year, approximately 30 to 40 million Americans travel outside the United States. Although the most popular destinations are Europe, Central America, and the Caribbean, travel to Africa and Asia is increasing substantially. International travel, particularly to developing countries, can be associated with the risk of infectious and noninfectious diseases. These risks can be decreased, eliminated, or modified with vaccinations, prophylactic medications, and education. Optimally, pretravel advice must be individualized to a person's medical history, itinerary, and risk behavior. In addition to risk assessment-based immunizations, issues such as traveler's diarrhea, malaria prophylaxis, sexually transmitted diseases, and management of underlying medical problems must form a part of pretravel management. Adventure or prolonged travel or persons with underlying medical diseases such as insulin-dependent diabetes mellitus, transplantation, immunodeficiencies, and dialysis warrant additional preventive measures. This review primarily updates pretravel management of adults. Each year, approximately 30 to 40 million Americans travel outside the United States. Although the most popular destinations are Europe, Central America, and the Caribbean, travel to Africa and Asia is increasing substantially. International travel, particularly to developing countries, can be associated with the risk of infectious and noninfectious diseases. These risks can be decreased, eliminated, or modified with vaccinations, prophylactic medications, and education. Optimally, pretravel advice must be individualized to a person's medical history, itinerary, and risk behavior. In addition to risk assessment-based immunizations, issues such as traveler's diarrhea, malaria prophylaxis, sexually transmitted diseases, and management of underlying medical problems must form a part of pretravel management. Adventure or prolonged travel or persons with underlying medical diseases such as insulin-dependent diabetes mellitus, transplantation, immunodeficiencies, and dialysis warrant additional preventive measures. This review primarily updates pretravel management of adults. As tourism grows, an increasing number of people are traveling to higher-risk destinations; thus, clinicians must become familiar with recommendations for travel health safety. Each year, 30 to 40 million Americans travel outside the United States.1Outbound travel from the US. Tourism Industries for International Trade Administration, US Dept of Commerce.Available at: http://tinet.ita.doc.gov/Google Scholar According to the World Tourism Organization, in 2000, world tourism in general grew by an estimated 7.4%, bringing the total number of international travelers to a record 698 million.2World Tourism Organization Web site.Available at: www.world–tourism.org/frameset/frame_market_data.htmGoogle Scholar This growth in tourism is considered the highest in almost a decade.2World Tourism Organization Web site.Available at: www.world–tourism.org/frameset/frame_market_data.htmGoogle Scholar Trends also indicate an increase of travel to African and Asian countries in the past decade. Medical problems are experienced by 20% to 70% of all travelers: 1% to 5% require medical care, 0.01% to 0.1% require emergency air evacuation, and 1 in 100,000 die.3Ryan ET Kain KC Health advice and immunizations for travelers.N Engl J Med. 2000; 342: 1716-1725Crossref PubMed Scopus (146) Google Scholar Although cardiovascular diseases are the most common cause of mortality among travelers, the mortality rate is similar to that for non-travelers. Specific travel-related mortality is higher because of accidents, which account for 21% to 26% of travel-related deaths.3Ryan ET Kain KC Health advice and immunizations for travelers.N Engl J Med. 2000; 342: 1716-1725Crossref PubMed Scopus (146) Google Scholar, 4Hargarten SW Baker TD Guptill K Overseas fatalities of United States citizen travelers: an analysis of deaths related to international travel.Ann Emerg Med. 1991; 20: 622-626Abstract Full Text PDF PubMed Scopus (161) Google Scholar, 5MacPherson DW Guérillot F Streiner DL Ahmed K Gushulak BD Pardy G Death and dying abroad: the Canadian experience.J Travel Med. 2000; 7: 227-233Crossref PubMed Scopus (58) Google Scholar Pretravel screening helps to stratify risk of the traveler. Risk stratification involves reviewing the itinerary, behavior patterns (such as eating habits), underlying medical history, and vaccine or medication contraindications. Details of the itinerary, lodging, budget, duration, and time to departure are extremely helpful in preparing the traveler for the trip. Prolonged travel, backpacking, low-budget travel, foreign-born individuals returning to visit friends and family, and imminent travel are associated with a higher incidence of travel-related complications. Medical problems or issues such as diabetes, transplantation, human immunodeficiency virus (HIV) or acquired immunodeficiency syndrome (AIDS), coronary artery disease, chronic obstructive pulmonary disease, and end-stage renal failure may substantially affect the immunogenicity of vaccines and implications for health while traveling. Live vaccines are contraindicated in immunocompromised or pregnant persons; thus, travel to a particular risk area is not possible. For example, patients who cannot receive the yellow fever vaccine should not travel to the Amazon. Allergies to vaccine components such as thimerosal or aluminum or to medications such as sulfonamides may preclude use of certain vaccines or medications. Contact allergy to thimerosal is not a contraindication to thimerosal-containing vaccines. Elderly persons or those with chronic medical diseases may benefit from a pretravel physical examination. Travelers should carry a letter stating medical diagnosis, list of medications with doses, and needles or syringes. Some medications, such as methylphenidate hydrochloride, are prohibited in certain countries. Carrying a letter from a physician may prevent problems at airports. Travelers should carry enough essential medications to last the duration of the trip, and the supply should be divided between carry-on and check-in baggage. Medications should be in original bottles with appropriate labels. Because dental problems can occur, patients with ongoing dental illnesses should have a dental examination before they travel to avoid invasive procedures in other countries. Most health insurance companies do not cover medical expenses that occur outside the United States. Travelers should consider additional travel health and air evacuation insurance, irrespective of their age, medical history, or type of travel. Studies have shown that 25% to 50% of travelers engage in sexual relations with new partners abroad, including other tourists, locals, or commercial sex workers.6Hawkes S Hart GJ Johnson AM et al.Risk behaviour and HIV prevalence in international travellers.AIDS. 1994; 8: 247-252Crossref PubMed Scopus (83) Google Scholar, 7Bloor M Thomas M Hood K et al.Differences in sexual risk behaviour between young men and women travelling abroad from the UK.Lancet. 1998; 352: 1664-1668Abstract Full Text Full Text PDF PubMed Scopus (68) Google Scholar Discussing alcohol consumption and safe sex with patients may help in preventing sexually transmitted diseases while traveling; this is especially relevant in light of increasing worldwide HIV prevalence. Patients should be advised to bring condoms from the United States because of poor availability or quality of condoms in some developing countries. Because accidents are the most common preventable cause of mortality during travel,8Leggat PA Klein M Personal safety advice for travelers abroad.J Travel Med. 2001; 8: 46-51Crossref PubMed Scopus (30) Google Scholar patients must be reminded to avoid high-risk situations, such as driving in a foreign country, riding 2-wheelers (motorcycles, scooters), or riding in overcrowded buses, particularly in adverse weather conditions or under the influence of alcohol. Travelers should follow basic traffic laws. Seat belt use should be encouraged, but the availability of functional seat belts may be severely limited in some developing countries. Illnesses related to air travel include motion sickness, barotrauma, hypoxemia in select patients, and possibly deep venous thrombosis (DVT). Motion sickness is common with flying. Patients can be advised to take either meclizine or dimenhydrinate for prophylaxis. Although airplanes are pressurized, expansion of air can occur and cause barotrauma in air-or gas-containing organs, particularly the ears, sinuses, and gastrointestinal tract. Swallowing or chewing during take-off and descent may decrease ear barotrauma. Ear barotrauma is more likely to occur in a traveler with a cold or an eustachian tube dysfunction. Occasionally, a serous otitis or tympanic membrane perforation can occur but usually resolves spontaneously. Because of air expansion, air travel is a relative contraindication for patients who have recently undergone abdominal surgery (previous 2 weeks). Patients with severe anemia (hemoglobin level <7 g/dL), sickle cell trait or disease, underlying chronic pulmonary obstructive disease and chronic hypoxia, or recent cerebrovascular accident may experience exacerbation of symptoms. Such patients may need to have oxygen on board, which must be arranged ahead of time with the airlines. Also, most airlines require a physician to verify the patient's ability to fly safely and to provide a certification called the Medical Fitness for Air Travel form. The available data suggest that an association, although small, exists between air travel and DVT.9Geroulakos G The risk of venous thromboembolism from air travel [editorial].BMJ. 2001; 322: 188Crossref PubMed Scopus (53) Google Scholar, 10Giangrande PL Thrombosis and air travel.J Travel Med. 2000; 7: 149-154Crossref PubMed Scopus (12) Google Scholar All patients, particularly those with risk factors such as a history of DVT, recent surgery or trauma, malignancy, obesity, pregnancy, or genetic prothrombotic predisposition and women taking oral contraceptives or hormone replacement therapy, should be advised to exercise their legs during the flight. The role of aspirin in the prevention of DVT is controversial. Compression stockings may be reasonable for patients at risk for DVT, and prophylactic anticoagulation should be considered for very high-risk patients. Jet lag and fatigue occur commonly in international travelers. Jet lag, typically worse when flying eastward, results from desynchronization of the sleep-wake cycle and other internal circadian rhythms, such as hormonal or temperature rhythms. For short and/or a series of short international flights (<72 hours), the patient should be advised to take brief naps at the corresponding home afternoon time or at late nighttime. Napping for less than 40 minutes avoids reverting to the home sleep cycle. For longer eastward trips, activities should be adjusted to correspond with time on the plane and on arrival. A mild bedtime sedative for 3 to 4 days after arrival at the destination or after return to the United States may help adjust the sleep cycle. Potential adverse effects, such as daytime drowsiness, that may interfere with planned activities or driving should be discussed. Patients could try the medication once before leaving home to ensure no adverse effects. Use of melatonin for jet lag is controversial and has not been clearly shown to be effective. An important part of advice to travelers is vaccination against common and travel-related vaccine-preventable diseases. A review of immunization against diseases such as diphtheria, measles, and polio is advised because some of these diseases are prevalent in many developing countries. Although specific travel-related vaccinations may not be cost-effective,11Behrens RH Roberts JA Is travel prophylaxis worth while? economic appraisal of prophylactic measures against malaria, hepatitis A, and typhoid in travellers.BMJ. 1994; 309: 918-922Crossref PubMed Scopus (103) Google Scholar they are beneficial and may be required or recommended depending on travel history. Vaccine recommendations are best individualized to each traveler's itinerary, activities, time before departure (for completion of schedules or to mount an adequate immune response), previous immunizations, and medical history. Travel vaccine schedules, boosters, common contraindications, and adverse effects are listed in Table 1.Table 1Common Vaccines for International Travelers*AIDS = acquired immunodeficiency syndrome; FDA = Food and Drug Administration; HBsAg = hepatitis B surface antigen; HIV = human immunodeficiency virus; IM = intramuscular; MMR = measles-mumps-rubella; NA = not available; OPV = oral polio vaccine; SQ = subcutaneous.Vaccine (efficacy)Primary courseBoosterAccelerated scheduleSpecific contraindications†Severe reaction to previous dose or moderate to severe ongoing illness precludes use of any vaccination.Adverse effects‡Pain at injection site, redness, swelling, occasional fever, and flulike symptoms can occur with any vaccine and are not contraindications to subsequent doses.Cholera (oral)§Not available in the United States. (60%-100%)NANANANANAHepatitis A (about 70%-80% at 2 wk; 95% at 4 wk)Adults ≥18 y: 1.0 mL IM in deltoid at 0 and 6 moNoneNoneAge <2 y; allergy to aluminum, aluminum hydroxide, or other vaccine components depending on vaccine used; pregnancy is relative contraindicationHeadacheHepatitis BAdults ≥20 y: 1.0 mL IM (20 μg) at 0, 1, 6 moNone unless anti-HBs antibody is <10 mIU/mL1.0 mL IM in deltoid at 0, 1, 4 mo or 0, 2, 4 mo (second dose at least 1 mo after first dose, third dose should be at least 4 mo after first dose and at least 2 mo after second dose); schedule of 0, 1, 2, 12 mo is FDA approved for Engerix-B vaccine onlyAge <20 y; allergy to thimerosal (mercury) or other components depending on vaccine used; hypersensitivity to yeast; pregnancy is relative contraindicationHeadache, nausea; rarely, anaphylaxis or other systemic effectsCombined hepatitis A and hepatitis BAdults ≥18 y: Havrix, 720 EL U/mL, and Engerix-B, 1.0 mL (with 20 μg of HBsAg) IM in deltoid at 0, 1, 6 moUnknown1.0 mL IM in deltoid on days 0, 7, 21 with a 12-mo boosterAge <18 y; allergy to aluminum, aluminum phosphate, aluminum hydroxide, 2-phenoxy-ethanol, formalin, thimerosal, neomycin, or yeast protein; pregnancy is relative contraindicationHeadache, nauseaγ-Globulin for hepatitis A prophylaxis‖Can be given at the same time as inactivated vaccines: OPV, yellow fever and oral typhoid vaccines; OPV should be repeated in 3 mo.Adults and children: IM deep into gluteus; trip duration: 2 y: 1.0 mL SQ on days 0, 7, 30; children 1–2 y: 0.5 mL SQ on days 0, 7, 30Same dose at least every 3 yAdults and children >2 y: 1.0 mL SQ on days 0, 7, 14; children 1–2 y: 0.5 mL SQ on days 0, 7, 14Age <1 y; allergy to thimerosal or gelatin; history of urticaria and allergies implies greater risk of allergic reactions to vaccine; last dose should not be given <10 d before travel; history of rash, hives, or generalized itching after bee stings or medications; pregnancyUrticaria, angio-edema; 16 to 64 cases per 10,000 vaccinees; systemic effects (fever, headache, aching, chills, dizziness, nausea, vomiting, abdominal pain, malaise) in 10% of recipientsMeningococcal (85%-90% after 1–2 wk)Adults and children ≥2 y: 0.5 mL SQ in a single doseAdults: same dose every 3–5 yNoneAge <2 y; allergy to thimerosal; pregnancyTransient fever in 2% of childrenPoliovirus (injectable)Adults ≥18 y: 0.5 mL SQ at 0, 2, 8–14 moSame dose repeated once if primary series completed at least 5 y previouslyPrimary series: 3 doses at 0, 1, 2 mo (minimum 4 wk apart); give as many doses as time allows and remaining doses can be completed either in endemic country (expatriates) or in United StatesAllergy to neomycin, polymyxin B, or streptomycin; pregnancyRarely, anaphylaxis or other systemic effectsRabies1.0 mL IM in deltoid on days 0, 7, and 21 or 28Unknown, possibly 5 y; check serology before giving boosterDays 0, 7, 21Allergy to vaccine component depending on vaccine used; pregnancy; meflo-quine, chloroquine can interfere with immune response to intradermal vaccineLocalized lymph-adenopathy, headache, myalgia, malaise, dizzinessTyphoid (injectable) (64%-72%)Adults and children ≥2 y: 0.5 mL IM in deltoid in adults, vastus lateralis in childrenSame dose every 2 yNoneAge <2 y; <2 wk before exposure; allergy to phenol; pregnancyHeadache, tremor, abdominal pain, vomiting, diarrhea, cervical painTyphoid (oral)§Not available in the United States.¶Refrigerate. Should be taken on an empty stomach (1 h before meals) with cool or lukewarm liquid. (50%-80%)Adults and children ≥6 y: 4 capsules orally every other day on days 0, 2, 4, 6Same dose every 5 yNoneAge 95%)Adults and children ≥9 mo: single dose of 0.5 mL SQSame dose every 10 yNoneAge <9 mo; immunocompro-mised#Immunocompromised state: HIV or AIDS, leukemia, lymphoma, generalized malignancy, undergoing long-term chemotherapy, radiation therapy, or taking large doses of corticosteroids (more than 2 mg/kg per day or more than 20 mg/d), status posttransplant, or fewer than 3 mo since completing therapy for any of these disorders.: off immuno-suppressants <3 mo; <8 wk since blood or plasma transfusion; received other live-antigen vaccines within past 4 wk (MMR, oral typhoid, varicella, or OPV); <10 d before arrival in area where yellow fever vaccine is indicated; allergy to eggs, chicken, gelatin, or egg protein; pregnancy or likelihood of pregnancy 3 mo after vaccineGenerally mild fever, headache, muscle ache 5 to 14 d after immunization; vaccine strain encephalitis or disease occurs rarely in infants or elderly persons* AIDS = acquired immunodeficiency syndrome; FDA = Food and Drug Administration; HBsAg = hepatitis B surface antigen; HIV = human immunodeficiency virus; IM = intramuscular; MMR = measles-mumps-rubella; NA = not available; OPV = oral polio vaccine; SQ = subcutaneous.† Severe reaction to previous dose or moderate to severe ongoing illness precludes use of any vaccination.‡ Pain at injection site, redness, swelling, occasional fever, and flulike symptoms can occur with any vaccine and are not contraindications to subsequent doses.§ Not available in the United States.‖ Can be given at the same time as inactivated vaccines: OPV, yellow fever and oral typhoid vaccines; OPV should be repeated in 3 mo.¶ Refrigerate. Should be taken on an empty stomach (1 h before meals) with cool or lukewarm liquid.# Immunocompromised state: HIV or AIDS, leukemia, lymphoma, generalized malignancy, undergoing long-term chemotherapy, radiation therapy, or taking large doses of corticosteroids (more than 2 mg/kg per day or more than 20 mg/d), status posttransplant, or fewer than 3 mo since completing therapy for any of these disorders. Open table in a new tab Vibrio cholerae causes outbreaks in many countries where sanitation and food and water hygiene are inadequate. Incidence of cholera is highest in Africa, accounting for 72% of global cholera. At present, an epidemic of V cholerae biotype eltor, is ongoing in South Africa. Peru, Ecuador, Guatemala, Nicaragua, and countries in the Middle East and Asia have ongoing seventh pandemic cases. Because the risk of cholera to an average traveler is low (0.01%-0.001% per month of stay in a developing country),12Ryan ET Calderwood SB Cholera vaccines.J Travel Med. 2001; 8: 82-91Crossref PubMed Scopus (20) Google Scholar a cholera vaccine is rarely indicated. However, vaccination is advised for persons working with refugee populations, those living in endemic-epidemic areas, and military personnel. Currently, cholera vaccine is not required for entry into any country. The parenteral vaccine has been discontinued in the United States because of its frequent adverse effects and brief and unreliable immunogenicity. Newer oral cholera vaccines (an inactivated whole cell-B subunit vaccine and a live attenuated CVD 103-HgR V cholerae 01 serogroup vaccine) provide better immunity (85%-90% and 60%-100%, respectively) with fewer adverse effects.12Ryan ET Calderwood SB Cholera vaccines.J Travel Med. 2001; 8: 82-91Crossref PubMed Scopus (20) Google Scholar Both of these vaccines are licensed in countries other than the United States. Therefore, the current best advice for travelers going to cholera-endemic areas is to adhere to strict food and water precautions and to learn self-management of severe watery diarrhea. Hepatitis A is a predominantly food-borne viral hepatitis that occurs worldwide. Risk is low in Australia, Japan, Korea, North America, and Europe including southern Europe. Hepatitis A is the most frequently occurring vaccine-preventable disease among travelers. Ingestion of fecally contaminated water or food, such as raw seafood, is the source of infection. The risk increases with indiscriminate eating habits, person-to-person contact, and prolonged travel duration. The risk of acquisition of hepatitis A among nonimmune travelers is 3 to 20 cases per 1000 nonimmune persons who stay in a developing country for at least a month.13Steffen R Kane MA Shapiro CN Billo N Schoellhorn KJ van Damme P Epidemiology and prevention of hepatitis A in travelers.JAMA. 1994; 272: 885-889Crossref PubMed Scopus (188) Google Scholar Approximately 10% of 1- to 14-year-old and 20% of 15- to 40-year-old patients with hepatitis A require hospitalization. Mortality increases with age, being greater than 2% in persons older than 40 years. The inactivated hepatitis A vaccines (Vaqta [Merck] and Havrix [SmithKline Beecham]), available in the United States since the mid-1990s, are extremely efficacious and safe. Both vaccines provide protective antibody levels in 94% to 100% of patients within 4 weeks of vaccination,14Prevention of hepatitis A through active or passive immunization: recommendations of the Advisory Committee on Immunization Practices (ACIP).MMWR Morb Mortal Wkly Rep. 1999; 48: 1-–37Google Scholar and both can be used interchangeably. Immunity among children younger than 2 years is limited because of poor immunogenicity. Maternal antibody interferes with immunity in children younger than 12 months. Immune response may be limited in immunocompromised hosts. US immigrants from countries with a high prevalence of hepatitis A who visit their home countries should be vaccinated according to hepatitis A serostatus because most are likely to be immune. Coadministration of passive immunity (85%-90% protection)14Prevention of hepatitis A through active or passive immunization: recommendations of the Advisory Committee on Immunization Practices (ACIP).MMWR Morb Mortal Wkly Rep. 1999; 48: 1-–37Google Scholar with γ-globulin should be reserved for high-risk patients traveling imminently (<2 weeks), such as elderly persons, children younger than 2 years, those with underlying medical problems, or immunocompromised persons. Concurrent administration of most vaccines is not contraindicated with γ-globulin except the measles-mumps-rubella vaccine and varicella vaccine. Because of the long incubation period of hepatitis A virus and the rapid onset of protection with the vaccine, the vaccine alone may be adequate in most healthy persons for whom travel is imminent. Areas with a high prevalence of hepatitis B include Asia, Africa, parts of South America, the Middle East, southern and western Pacific islands, Haiti, and the Dominican Republic. Risk of hepatitis B for travelers is mainly associated with medical or dental care abroad, potential blood transfusion for an accident or illness, and sexual or needle exposures. Expatriation and frequent or prolonged international travel to developing countries are indications for initiating inactivated recombinant hepatitis B vaccination (Recombivax HB [Merck]; Engerix-B [SmithKline Beecham]). Health care workers, volunteers, or missionaries in developing countries require the hepatitis B vaccine series. For patients leaving imminently, an accelerated schedule can be used to achieve protective immunity. Currently, only Engerix-B has received approval from the Food and Drug Administration (FDA) for an accelerated schedule of 0, 1, and 2 months with a 12-month booster. A new combined hepatitis A (Havrix [720 EL U/mL]) and hepatitis B (Engerix-B [20 μg of recombinant hepatitis B surface antigen]) vaccine called Twinrix (SmithKline Beecham) was approved by the FDA in 2001 for use in adults older than 18 years. Twinrix is given on a 0-, 1-, and 6-month schedule. Studies have shown that Twinrix is as efficacious as the monovalent vaccines of Havrix (99% of the vaccinees are seropositive at 2 months) and for hepatitis B (84% of the vaccinees are seropositive at 2 months).15Steffen R Immunization against hepatitis A and hepatitis B infections.J Travel Med. 2001; 8: S9-S16Crossref PubMed Scopus (11) Google Scholar This vaccine is convenient for long-term travelers and for those who need rapid protection.16Thoelen S Van Damme P Leentvaar–Kuypers A et al.The first combined vaccine against hepatitis A and B: an overview.Vaccine. 1999; 17: 1657-1662Crossref PubMed Scopus (118) Google Scholar An accelerated schedule of 0, 7, and 21 days with a 12-month booster is as efficacious as a standard schedule.15Steffen R Immunization against hepatitis A and hepatitis B infections.J Travel Med. 2001; 8: S9-S16Crossref PubMed Scopus (11) Google Scholar Indications for this vaccine are similar to those for hepatitis B vaccine in travelers. Japanese B encephalitis is a mosquito-borne viral encephalitis that occurs in rural parts of Asia, especially near pig farms. It is prevalent in China, the Indian subcontinent, Japan, eastern Russia, and other Southeast Asian countries. It has seasonal variation (more in summer, rainy months). Japanese B encephalitis has a 30% case fatality rate in patients with overt infections, with high neuropsychiatric sequelae. Risk of acquisition is mainly associated with extensive (=4 weeks) rural travel, backpacking, or rain forest travel in endemic countries. The full course of the inactivated Japanese B encephalitis vaccine (Biken) results in seroconversion in 100% of recipients, and neutralizing antibodies remain for at least 3 years. Common adverse effects like myalgias, headache, or fever occur in 20% of vaccine recipients, and hypersensitivity reactions (generalized urticaria, angioedema, respiratory distress, and anaphylaxis) occur in 0.6% of recipients.17Inactivated Japanese encephalitis virus vaccine: recommendations of the Advisory Committee on Immunization Practices (ACIP).MMWR Morb Mortal Wkly Rep. 1993; 42: 1-–15PubMed Google Scholar Hypersensitivity reactions can be immediate or delayed up to 10 days and are more likely in persons with a history of urticaria or other allergies. Patients with Japanese B encephalitis must defer international travel and remain in areas with ready access to medical care for 10 days after receiving a dose of the vaccine. Certain areas of the world, especially central Africa, have seasonal epidemics caused by Neisseria meningitidis, mostly serogroups A or C, during the dry seasons (December through June). N meningitidis is also an important cause of disease among travelers taking the Hajj pilgrimage in Saudi Arabia, and vaccination is required for entry into Saudi Arabia. The currently available vaccine in the United States (Menomune [Aventis]) is effective only against serogroups A, C, Y, and W-135 and does not cover serogroup B. Since October 1999, meningococcal vaccine has been recommended for college students living in US dormitories. Requirements are similar for students traveling abroad to study in other countries, such as the United Kingdom. Although poliomyelitis is reaching near eradication worldwide, pockets with ongoing wild strain transmission still exist, such as in African countries and in Asia. Poliomyelitis was declared eradicated from the Western Hemisphere until a recent outbreak of vaccine-strain polio in Haiti and the Dominican Republic. Currently, all travelers to Haiti, the Dominican Republic, eastern Europe, Africa, and Asia are advised to receive a 1-time adult parenteral inactivated trivalent polio vaccine booster if the primary series has been completed. Unlike the United States where the principal vectors for rabies are wild animals or bats, in many parts of the world, particularly India, Nepal, Mexico, Colombia, Ecuador, El Salvador, Guatemala, Peru, Philippines, Sri Lanka, Thai