Immunizations
Required Vaccinations
Yellow Fever
This viral infection is transmitted by the day-time biting Aëdes aegypti mosquito typically found in urban, suburban, and rural areas.
A Yellow Fever vaccination certificate is only required for travellers coming from a country with risk of Yellow Fever transmission. The vaccination requirement is imposed by this country for protection against Yellow Fever since the principal mosquito vector Aëdes aegypti is present in its territory.
Risk of Yellow Fever transmission exists in these countries:
AFRICA - Angola, Benin, Burkina Faso, Burundi, Cameroon, Central African Republic, Chad, Republic of the Congo, Democratic Republic of the Congo, Côte d'Ivoire, Equatorial Guinea, Ethiopia, Gabon, Gambia, Ghana, Guinea, Guinea-Bissau, Kenya, Liberia, Mali, Mauritania, Niger, Nigeria, Rwanda, Senegal, Sierra Leone, South Sudan, Sudan, Togo, Uganda.
AMERICAS - Argentina, Bolivia, Brazil, Colombia, Ecuador, French Guiana, Guyana, Panama, Paraguay, Peru, Suriname, Trinidad and Tobago, Venezuela.
Note: A vaccination certificate is required for children over one year of age.
If your medical practitioner has advised you against the Yellow Fever vaccine for medical reasons, a vaccination waiver should be issued. Be aware that problems may arise when crossing borders and your vaccination waiver may not be honoured. See example of a Yellow Fever vaccination waiver.
Recommended Vaccinations
Routine Immunizations
Your trip is a good occasion for a reminder to keep your routine immunizations updated; more than 80% of adults in developed countries have not maintained their immunization status. The following vaccinations are recommended for your protection and to prevent the spread of infectious diseases.
Tetanus, Diphtheria, Pertussis, Measles, Mumps, Rubella, Poliomyelitis should be reviewed and updated if necessary. Note: Many of these vaccine preventable illnesses are making a resurgence due to non-vaccination, incomplete vaccination, and waning immunity. It is important to keep your routine immunization up-to-date.
Seasonal influenza vaccination is recommended for all travellers over 6 months of age, especially for children, pregnant women, persons over 65, and those with chronic health conditions such as asthma, diabetes, lung disease, heart disease, immune-suppressive disorders, and organ transplant recipients. Note: In the northern hemisphere the flu season typically runs from November to April and from April to October in the southern hemisphere. If the flu vaccine is not available at the time of departure, contact your doctor or travel health clinic regarding influenza anti-viral protection.
Pneumococcal vaccine is recommended for persons over the age of 65 and persons of any age suffering from cardiovascular disease, diabetes, renal disorders, liver diseases, sickle cell disease, asplenia, or immuno-suppressive disorders.
Hepatitis A
The Hepatitis A virus (HAV) is primarily transmitted from person to person via the fecal-oral route and through contaminated water and food - such as shellfish, and uncooked vegetables or fruit prepared by infected food handlers.
The virus is present worldwide, but the level of prevalence depends on local sanitary conditions. HAV circulates widely in populations living in areas with poor hygiene infrastructure. In these areas, persons usually acquire the virus during childhood when the illness is asymptomatic (but still infective to others) or mild, and end up developing full immunity. Large outbreaks in these countries are rare. In contrast, a large number of non-immune persons are found in highly industrialized countries where community wide outbreaks can occur when proper food handling or good sanitation practices are not maintained including in daycare centres, prisons, or mass gatherings.
In many cases, the infection is asymptomatic (persons do not exhibit symptoms). Those with symptoms will usually get ill between 15 to 50 days after becoming infected. Symptoms include malaise, sudden onset of fever, nausea, abdominal pain, and jaundice after a few days. The illness can range from mild to severe lasting from one to two weeks or for several months. Severe cases can be fatal especially in older persons. Most infections are asymptomatic in children under six years of age, but infants and children can continue to shed the virus for up to six months after being infected, spreading the infection to others. Many countries are now including vaccination against Hepatitis A in their childhood vaccination schedules.
Prevention: Practice good personal hygiene, including washing your hands frequently and thoroughly, drink boiled or bottled water, eat well cooked foods, and peel your own fruits.
All non-immune persons, especially travellers, should be vaccinated. Two vaccines are available for persons over one year of age. Two doses are needed for full protection (the second dose is given 6 to 12 months after the first dose (HAVRIX) or 6 to 18 months after the first dose (VAQTA). TWINRIX is a vaccine against Hepatitis A and Hepatitis B. It is available for persons over 18 years of age. Three doses are needed for full protection. The second dose is given 1 month after the first, and the third 6 months later. For an accelerated schedule four doses are needed at 0, 7, 21, 31 days and the last dose 12 months later.
Typhoid Fever
This intestinal infection, caused by Salmonella typhi bacteria, is transmitted from person to person primarily through ingestion of contaminated food and water in areas with poor sanitary and hygienic conditions. Prevention includes good personal hygiene such as washing your hands frequently, ensuring safe water supply, eating well cooked foods, and peeling your own fruits. Vaccination is also recommended for travellers' protection.
Selective Vaccinations
Cholera
Cholera is an acute gastro-intestinal infection caused by vibrio cholerae bacteria. Risk of infection to travellers is low and vaccination is advised only for medical and rescue personnel working in endemic areas.
The best protection is to avoid potentially contaminated water and food. See IAMAT's 24 World Climate and Food Safety Charts describing the sanitary condition of water, dairy products, and food in 1440 cities. Meticulous food and water hygiene are essential when travelling in endemic areas.
Persons living and working in inadequate sanitary conditions and those with impaired defence mechanisms (deficient production of gastric acid due to surgery for duodenal or gastric ulcers), persons on antacid therapy, and users of cannabis (smoking marijuana reduces acid secretion of the stomach) are more susceptible to cholera infection. The World Health Organization announced in 1991 that Cholera vaccination certificates are no longer required by any country or territory.
Hepatitis B
The Hepatitis B virus (HBV) is transmitted through infected blood products, sexual intercourse, or infected items such as needles or razor blades, and may cause severe liver damage.
Vaccination is recommended for persons on working assignments in the health care field (dentists, physicians, nurses, laboratory technicians), or for those working in close contact with the local population (teachers, aid workers, missionaries), or persons foreseeing sexual relations with locals. This vaccine is often combined with the Hepatitis A vaccine and affords excellent long-term protection for both viral diseases.
Rabies
This viral infection is transmitted through the saliva of infected animal bites which affects the brain and the spinal cord, and may be fatal.
A series of three (3) pre-exposure rabies vaccination shots is advised for persons planning an extended stay or on working assignments in remote and rural areas, particularly in Africa, Asia, Central and South America. The pre-exposure series simplifies medical care if the person has been bitten by a rabid animal. Although this provides adequate initial protection, a person potentially exposed to rabies will require two (2) additional post-exposure innoculations.
Persons who have not received the pre-exposure shots need five (5) injections in addition to rabies immune globulin (RIG). RIG is in short supply around the world and may not be available in remote areas. If a traveller has had the three pre-exposure shots, they will only need additional two shots; they do not need RIG.
Children are especially vulnerable since they may not report scratches or bites. They should be cautioned not to pet dogs, cats, monkeys, or other mammals. Any animal bite or scratch must be washed repeatedly with copious amounts of soap and water. Seek medical attention immediately.
The recommendations for vaccinations outlined above are intended as guidelines only. Your immunization needs depend on your health status, previous immunizations received, and your travel itinerary. Seek further advice from your doctor or travel health clinic.
Health Risks
MALARIA
Infection is spread by the night-time - dusk to dawn - biting female Anopheles mosquito.
Malaria risk is present throughout the country, including urban areas, except areas specified:
The city of Sana'a is (2377m / 7799ft) is risk free.
Malaria risk is present below the altitude of: 2000 meters
High risk months for Malaria are: January - December
Malaria transmission vector(s): A. stephensi stephensi
Incidence of Plasmodium falciparum Malaria: 95%
Of the five species of human malaria parasites, Plasmodium falciparum is the most dangerous. The remaining percentage represents malaria infections that may be caused by one or more of the following parasites: Plasmodium vivax, Plasmodium ovale, Plasmodium malariae, and Plasmodium knowlesi.
Areas with drug resistant Malaria: Multi-drug resistant (chloroquine and sulfadoxine-pyrimethamine) P. falciparum malaria is present in all malarious areas of Yemen.
Suppressive Medication Guide:
For details on anti-malarial drug side-effects, dosages for children and pregnant women, medications used around the world, and comprehensive protection measures, see: How to Protect Yourself Against Malaria (pdf)
SCHISTOSOMIASIS
Infection is transmitted by snails living in fresh water such as lakes, rivers, streams and ponds in the Caribbean, South America, Africa, and Southeast Asia.
Schistosomiasis risk is present in the whole country, including urban areas:
All populated areas of Yemen are highly endemic with both S. haematobium and S. mansoni. Travellers should consider all oases, open wells and temporary water bodies in the desert areas infected. Additional snail intermediate hosts for S. haematobium: Bulinus beccari and Bulinus wrighti.
There is a risk of Schistosomiasis caused by: Schistosoma haematobium, Schistosoma mansoni
The main intermediate host snail is: Bulinus truncatus, Biomphalaria alexandrina, Biomphalaria pfeifferi, Biomphalaria arabica, See text for intermediate snail host.
Prevention Guidelines:
OTHER HEALTH RISKS OF INTEREST TO TRAVELLERS
Air Pollution
Outdoor air pollution (a mix of chemicals, particulate matter, and biological materials that react with each other) contributes to breathing problems, chronic diseases, increased hospitalization, and premature mortality. Cities and rural areas around the world are affected by air pollution.
No matter where you travel, you will not be able to escape air pollution. Exposure and concentration of pollutants can affect your health. When planning your trip, consider your health status, age, destination, length of trip and season to help you mitigate the effects of air pollution.
Short term symptoms of exposure to air pollution include itchy eyes, nose and throat, wheezing, coughing, shortness of breath, chest pain, headaches, nausea, and upper respiratory infections (bronchitis and pneumonia). It also exacerbates asthma and emphysema. Long term effects include lung cancer, cardiovascular disease, chronic respiratory illness, and developing allergies. Air pollution is also associated with heart attacks and strokes.
Prevention: Comply with air pollution advisories (ask around and observe what locals are doing) and avoid strenuous activity. If you have asthma or chronic obstructive pulmonary disease (COPD), carry an inhaler, antibiotic, and oral steroid (consult your doctor to see what is best for you). It is recommended that older travellers get a physical exam that includes a stress and lung capacity test prior to departure. Newborns and young children should minimize exposure as much as possible or consider not travelling to areas with poor air quality. Ask your medical practitioner if a face mask is advisable for you.
>> For city and country air pollution levels, see the World Health Organization.
Chikungunya
Chikungunya is a viral infection transmitted to humans through the bite of infected daytime biting female mosquitos. The Aëdes aegypti mosquito is the primary vector, but the Aëdes albopictus mosquito is also responsible for transmitting the virus belonging to the Alphavirus genus of the Togaviridae family.
Travellers going to sub-Saharan Africa, southeast Asia, and the Indian subcontinent are at risk. The mosquitos usually bite early morning and late afternoon and are typically found in and around domestic dwellings. Some mosquitos carrying the Chikungunya virus in Africa also live in forested areas. Monkeys and other wild animals are also believed to be reservoirs for the virus. Isolated cases of imported Chikungunya have occurred in the Americas and Europe.
The initial symptoms of sudden fever and sever muscle and joint pain usually appear between 3 to 7 days and sometimes until 12 days after the bite. Not everyone exhibits symptoms and the infection may go undetected. Other symptoms include headache, fatigue nausea, vomiting, and a rash. Although most patients fully recover, chronic joint pain may last for several weeks or months. Other persistent problems may include eye, gastrointestinal, neurological, and heart complications. Sometimes Chikungunya is misdiagnosed in areas where Dengue also occurs.
Persons with chronic health conditions, compromised immune systems, newborns, the elderly are at risk of developing complications with this infection. Chikungunya is rarely fatal.
Prevention: Travellers should take measures to prevent mosquito bites both indoors and outdoors, especially during the daytime. Insect-bite prevention measures include applying a DEET-containing repellent to exposed skin, applying permethrin spray (or solution) to clothing and gear, wearing long sleeves and pants, getting rid of water containers around dwellings and ensuring that door and window screens work properly. There is no preventive vaccine against Chikungunya.
Country at risk for Chikungunya.
Dengue
Dengue is a viral infection caused by four types of viruses (DENV) belonging to the Flavivirdae family. The viruses are transmitted through the bite of infected Aëdes aegypti and Aëdes albopictus female mosquitoes that feed both indoors and outdoors during the daytime (from dawn to dusk). Dengue is present in tropical and subtropical areas of Central America, South America, Africa, Asia, and Oceania. It's found predominantly in urban and suburban settings and higher rates of transmission occur during rainy seasons.
All travellers are at risk during epidemics. Long-term travellers and aid or missionary workers going to areas where Dengue is endemic are at higher risk.
In some cases, Dengue infection is asymptomatic (persons do not exhibit symptoms). Those with symptoms get ill between 4 to 7 days after the bite. The infection is characterized by flu-like symptoms which include a sudden high fever coming in separate waves, pain behind the eyes, muscle, joint, and bone pain, severe headache, and a skin rash characterized by bright red spots.
The illness may progress to Dengue Hemorrhagic Fever (DHF). Symptoms include severe abdominal pain, vomiting, diarrhea, convulsions, bruising, and uncontrolled bleeding. High fever can last from 2 to 7 days. Complications can lead to circulatory system failure and shock, and can be fatal. Exposure to one type of Dengue virus does not provide immunity to the other three types. Contracting Dengue more than once increases the risk of developing Dengue Hemorrhagic Fever.
Prevention: Travellers should take measures to prevent mosquito bites during the daytime. Insect-bite prevention measures include applying a DEET-containing repellent to exposed skin, applying permethrin spray (or solution) to clothing and gear, wearing long sleeves and pants, getting rid of water containers around dwellings and ensuring that door and window screens work properly. There is currently no preventive medication or vaccine against Dengue.
Leishmaniasis
Leishmaniasis is a parasitic infection caused by different species of Leishmania protozoa. It is transmitted through the bite of infected female sandflies (Phlebotomus, Lutzomyia, and Psychodopygus species). These nocturnal insects bite from dusk to dawn and are often found in forests, stone and mud walls cracks, and animal burrows. They are very tiny silent flyers (they do not hum) and their bite might go unnoticed.
Persons at risk of exposure to sand flies include adventure travellers, bird watchers, missionaries, army personnel, construction workers, and researchers on night time assignments. Leishmaniasis is clinically divided into three major categories: cutaneous, mucocutaneous, and visceral.
Cutaneous leishmaniasis is the most common form of the infection and is divided into two geographic areas of occurence:
- Old World cutaneous leishmaniasis is present in the Mediterranean basin (southern Europe and North Africa), the Middle East, Southwest and Central Asia, and the tropical areas of Africa. The majority of cases are reported from the following countries: Afghanistan, Algeria, Iran, Iraq, Saudi Arabia and Syria. Old World cutaneous leishmaniasis is a mostly self-limiting skin disease in adults, but depending on the species, infected infants and children can develop the visceral form of the disease.
- New World cutaneous leishmaniasis is common in rural areas but can also be acquired in semi-urban and urban areas. It also occurs in rainforests and arid areas. New World cutaneous leishmaniasis is present in parts of North America (occasional cases are reported from the states of Texas and Oklahoma), Mexico, Central and South America, with Brazil and Peru reporting the majority of cases.
Symptoms of cutaneous leishmaniasis include skin lesions (which develop after several weeks to months after infection) and swollen glands. The lesions - closed or open sores - can change overtime in size and appearance, they are usually painless, but can become painful if infected with bacteria. The lesions can take a long time to heal and usually leaves scarring.
Infections with some strains of New World cutaneous leishmaniasis may develop into mucocutaneous leishmaniasis, years after the initial skin lesions seem to have healed completely. The infection spreads to the nose, mouth, and throat causing sores and bleeding. This complication can occur when the initial cutaneous leishmaniasis has not been treated.
Visceral leishmaniasis, also know as kala-azar, is caused by some Leishmania species that invade the liver, spleen, bone marrow, and skin.
Symptoms include fever, weight loss, and enlarged liver. Advanced untreated visceral leishmaniasis can be fatal, particularly if other underlying medical conditions such as tuberculosis, pneumonia, and dysentry are present. This form of leishmaniasis is very rare in travellers but it affects local populations in remote areas of India, Nepal, Bangladesh, Sudan, South Sudan, Ethiopia, and Brazil.
Prevention: Avoid dusk to dawn outdoor activities. Presoak protective clothing with permethrin insecticide. Use insect repellent containing DEET on exposed skin and sleep under permethrin treated bed nets or in air conditioned areas. (Sand flies are very small, 2-3 mm, and may be able to enter through regular screens and nettings. Insecticide treated screens and nets can reduce risk of entry). There is no preventive vaccination or medication against leishmaniasis. Treatment options depend on identifying the infective leishmania species and the extent of the infection, but generally includes antifungal and antibacterial ointments.
>> For Leishmaniasis images, life cycle, and distribution maps, see Infection Landscapes.
Leishmaniasis is endemic in Yemen. Cutaneous leishmaniasis commonly occurs in semirural villages of the Asir mountains. Visceral leishmaniasis occurs sporadically in rural areas, usually in the foothill region or the Asir mountains, at elevations between 400 and 1500 metres.
Leptospirosis
Leptospirosis is caused by bacteria belonging to the genus Leptospira. It is a zoonosis (an animal disease that can spread to humans) affecting domestic and wild animals such as cattle, dogs, cats, pigs, and rodents. Humans can become sick when they come into contact with water, food, soil, and mud contaminated with the urine of infected animals. The bacteria can enter through skin abrasions and mucous membranes of the mouth, eyes, and nose. Leptospirosis occurs worldwide, but is endemic (usually seasonally) in tropical and subtropical areas with poor sanitation and in agricultural areas with livestock operations or rodent infestations. Outbreaks can also occur after storms, heavy rainfalls, or floods.
Travellers involved in adventure travel or outdoor activities such as swimming, canoeing, whitewater rafting, kayaking, or camping are at risk. Visiting farms, rice paddies, or sugar cane fields can also increase risk of exposure. Leptospirosis is an occupational hazard for farmers, veterinarians, rescue workers and military personnel.
The infection is characterized by flu-like symptoms which can appear anywhere from 2 to 30 days (usually 7 to 10 days) after being infected. Symptoms include sudden fever, headache, muscle pain, chills, red itchy eyes, difficulty urinating, a skin rash, nausea, vomiting, and diarrhea. A second, more severe, phase of the illness – also known as Weil's disease – may progress to kidney or liver failure, jaundice, cardiac failure, meningitis (inflammation of the brain), and respiratory failure. Treatment usually includes antibiotics. Human to human transmission of leptospires bacteria is rare.
Prevention: Avoid swimming or wading in water potentially contaminated with urine, including in canals, swamps, lakes, and rivers. If this cannot be prevented, wear protective clothing and footwear when coming into contact with potentially infected water, soil, or animals. Outdoor sports travellers and persons with occupational risk may want to consult their healthcare provider about taking preventive medication to avoid infection. In North America, there is currently no commercially available vaccine against Leptospirosis.
Sexually Transmitted Infections
Avoid unprotected sexual contact. If you are going to have sex with a stranger, use latex or polyurethane condoms consistently and correctly. Bring your own condoms from home.
Some countries continue to have entry restrictions for travellers with HIV / AIDS. See NAM aidsmap for details on this country.
Traveller's Diarrhea
Diarrhea is the most common cause of illness during travel. The source of illness is the ingestion of contaminated food or water, person-to-person transmission, or recreational exposure to water bodies. The infective agents can be bacteria, viruses, protozoa or toxins found in food. Good personal hygiene practices (including frequent and thorough hand washing), proper food handling, and water purification are the most effective methods to prevent infection.
Consult your doctor for the best treatment options tailored to your needs, including taking prescription medication on your trip in case you suffer from diarrhea. Travellers with chronic conditions are more susceptible to infections and should consider taking preventive medication.
See our Guide to Healthy Travel for prevention and treatment tips.
Tuberculosis
Tuberculosis (TB) is an airbone bacterial infection caused by Mycobacterium tuberculosis. TB can be acquired by breathing contaminated air droplets coughed or sneezed by a person nearby who has active Tuberculosis. Humans can also get ill with TB by ingesting unpasteurized milk products contaminated with Mycobacterium bovis, also known as Bovine Tuberculosis.
Tuberculosis occurs worldwide and commonly spreads in cramped, overcrowded conditions. The most common form of the infection is pulmonary TB which affects the lungs. In some cases, the bacteria can also attack the lymphatic system, central nervous system, urogenital area, joints, and bones.
The risk for travellers is low. There is no evidence that pulmonary TB is more easily transmitted in airplanes or other forms of public transportation. However, travellers with immuno-compromised systems, long-term travellers, and those visiting friends and relatives in areas where Tuberculosis is endemic are at greater risk. Humanitarian and healthcare personnel working in communities with active TB are also at increased risk. Persons with active TB should not travel.
- The majority of persons with the illness (90% to 95% of the population) have latent TB infection (LTBI) and do not exhibit any symptoms. The bacteria can remain inactive for many years and the chance of developing active TB diminishes over time.
- Persons with active TB have symptoms which include excessive coughing (sometimes with blood), chest pain, general weakness, lack of appetite, weight loss, swollen lymph glands, fever, chills, and night sweats. It can be misdiagnosed for bronchitis or pneumonia. If untreated, active TB can lead to fatalities.
Tuberculosis treatment involves taking antibiotics for a minimum of 6 months. Drug-resistant TB is a major concern as an increasing number of people are no longer able to be treated with previously effective drugs. Due to misuse of antibiotic therapies, patients can develop multi-drug resistant Tuberculosis (MDR TB). When a second line of antibiotics fail to cure the multi-drug resistant infection, it is known as extensively drug-resistant Tuberculosis (XDR TB).
Prevention: Avoid exposure to people known to who have active Tuberculosis and only consume pasteurized milk products. Travellers at higher risk should have a pre-departure tuberculin skin test (TST) and be re-tested upon their return home. Those at increased risk should also consult their healthcare provider to determine if the Bacillus Calmette-Guérin (BCG) vaccine is recommended.
Tuberculosis is highly endemic in Yemen.
LOW HEALTH RISKS TO TRAVELLERS
Brucellosis
Brucellosis is a zoonosis (an animal infection that can spread to humans) caused by the Brucella bacteria. It typically affects livestock such as cattle, sheep, goats, pigs, camels, bison, and dogs.
Travellers are at risk of brucellosis when coming into contact with infected animals or contaminated animal products. Brucellosis usually appear between 5 and 60 days, sometimes longer. It can be contracted through:
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Ingestion by eating or drinking contaminated milk products.
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Inhalation, although not common, mostly affects abattoir employees or lab workers doing research on the bacteria.
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Skin lesions where the bacteria invade the blood stream, usually affects meat packers, abattoir workers, veterinarians, and hunters.
Symptoms include fever, headaches, sweats, back pain and general weakness. In more severe cases, the bacteria attacks the central nervous system and the heart, and patients suffer from chronic joint pain, fatigue and recurring fevers. Person to person transmission of brucellosis is extremely rare.
Prevention: Avoid unpasteurized milk products, including fresh cheeses or ice cream. If you are not sure whether the product is pasteurized or not, avoid eating it. Wash your hands thoroughly and frequently with soap and water or use an alcohol based hand sanitizer if coming into contact with animals. There is no preventive medication or vaccination available against brucellosis for humans.
Echinococcosis
Echinococcosis is a potentially fatal parasitic disease that affecting wildlife, commercial livestock and humans. Humans become infected by accidentally swallowing the eggs of the E. multilocularis tapeworm. Humans can be exposed to these eggs by directly ingesting food contaminated with stool from infected foxes or coyotes. This might include grass, herbs, greens or berries collected from fields. Humans may also be contaminated by petting infected cats or dogs. These pets may shed the tapeworm eggs in their stool and their fur may be contaminated.
Basic hygiene practices such as thoroughly cooking food and vigorous hand washing before meals can prevent the infective eggs entering the human digestive tract.
Murine Typhus
Endemic typhus (murine typhus) is caused by the bacteria Rickettsia typhi and is transmitted by fleas that infest rats, especially during exposure in rat-infested premises, such as warehouses, stores, and grain elevators. Flea-infested rats can be found throughout the year in humid tropical environments, especially in harbour or riverine environments. In temperate regions, they are most common during the warm summer months.
Limiting exposure to vectors or animal reservoirs remains the best means for reducing the risk of disease. Risk for travellers is low. Persons who are occupationally exposed to rats ( naturalists, geologists, agricultural workers) should avoid vector-infested habitats, use repellents and wear protective clothing.
Food and Water Safety
All local water should be considered contaminated. All tap water used for drinking, brushing teeth, and making ice cubes should be boiled (bringing water to a good rolling boil is sufficient). Good brands of bottled water are available; check cap seal and ensure that the bottle is uncapped in your presence.
Milk should be boiled before consumption because of possible improper refrigeration during distribution. Powdered and evaporated milk are available and safe. Butter should not be used as a table food. Cream, ice cream, and whipped cream should not be consumed. Cheese, unless cured, is best avoided. Yoghurt is safe only if it is known to be made from pasteurized milk.
All meat, poultry, and fish must be well cooked and served while hot. Pork is best avoided; vegetables should be well cooked and served hot. Salads are best avoided. Fruits with intact skins should be peeled by you just prior to consumption. Avoid raw and undercooked eggs, and dishes prepared with raw eggs (steak tartar, mayonnaise, and dressings). Avoid cold buffets, uncured cheeses, custards, and any frozen desserts.
First rate hotels and restaurants serve purified drinking water and reliable food. However, the hazard is left to your judgement.
Gastro-intestinal infections are the most common illnesses affecting travellers and can occur in any country you are visiting. Proper food handling, drinking purified water, and maintaining good personal hygiene are key to prevention. Below is a summary of the agents causing gastro-intestinal illnesses.
Bacterial Contamination
It is estimated that about 85% of traveller’s diarrhea is caused by bacteria of which the following are the most important agents:
Enterotoxigenic Escherichia coli (ETEC) and Enteroaggregative Escherichia coli (EAEC) account for most cases of traveller’s diarrhea associated with contaminated food and water world wide. They are the cause of large outbreaks in developed countries when food and water sanitation have not been properly maintained. Symptoms include watery stools, abdominal cramps, and possible vomiting lasting three to seven days.
Campylobacter jejuni is more prevalent in developing countries and is associated with contaminated water, undercooked food, and unpasteurized milk. Symptoms include diarrhea, abdominal cramps, and fever lasting from two to ten days.
Salmonella enteritidis is associated with contaminated eggs, poultry, milk, fruits, and uncooked vegetables. Symptoms include diarrhea, vomiting, abdominal cramps, and fever lasting from four to seven days. Infected persons can become asymptomatic carriers and shed the bacteria for years, becoming the source of infection for others through poor hygiene practices.
Shigellosis is a human infection caused by one of four species and transmitted by fecal-oral route due to unsanitary conditions, contaminated food and water, and overcrowded living conditions. Symptoms include diarrhea, abdominal cramps, fever, and may cause bloody diarrhea and mucous lasting four to seven days.
Vibrio cholera is associated with contaminated water, raw and undercooked seafood. Cholera infection in travellers is rare; symptoms include watery diarrhea and vomiting lasting three to seven days, but can lead to severe dehydration and death in undernourished persons. Vibrio parahaemolyticus is also related to the consumption of raw and undercooked seafood. Vibrio vulnificus is associated with contaminated shellfish and raw oysters in particular, and has caused septicemia in persons with liver disorders.
Viral Contamination
Gastro-intestinal infections caused by viruses account for about 5%. The main agents are Norovirus, associated with outbreaks at large gatherings and on cruise ships, and Rotavirus, which is more prevalent in developing countries. Symptoms include vomiting, diarrhea, fever, and myalgia lasting 12 to 60 hours.
Protozoal Contamination
Gastro-intestinal infections with protozoa account for about 10% of traveller’s diarrhea, but may cause prolonged illnesses (lasting weeks) and cause serious complications if not diagnosed in a timely manner.
Giardia lamblia (Giardiasis) and Entamoeba hystolytica (Amebiasis) are the most important agents in this category and both infections are acquired through contaminated food and water, as well as person to person transmission due to poor hygiene practices. Cryptosporidium and Cyclospora cayetanensis are implicated with contaminated food, water, and fresh produce (berries).
Toxins Causing Food Poisoning
Clostridium perfringens is the most important agent causing food poisoning in developed countries. The spores of the bacterium germinate on cooked food that is cooled and stored at room temperature over a prolonged period of time. After ingestion, the spores produce an enterotoxin in the small intestine causing abdominal pain, diarrhea, and vomiting. Foods implicated are meats and poultry.
Staphylococcus aureus enterotoxins are spread by unsanitary practices of infected persons. The foods implicated are custards, creamy desserts, meats, and salads.
Clostridium botulinum bacteria produce a very potent toxin. It is associated with improperly canned food, lightly preserved vegetables, salted fish, and meats. Symptoms include nausea, vomiting, and neurological symptoms such as blurred and double vision, paralysis of respiratory and motor muscles that may progress rapidly.
Seafood Poisoning
Fish and shellfish can be contaminated with the toxins produced by marine micro-organisms called dinoflagellates found in all oceans, especially in coral reef areas. Larger fish have usually more toxins accumulated in the skin, musculature, and organs, as these toxins are passed up through the food chain. The toxins are not destroyed through cooking, smoking, or freezing, they are odorless and tasteless, and do not alter the appearance of the fish.
Ciguatera Fish poisoning is the most common illness in this category. The most affected fish are amberjack, barracuda, grouper, kahala, parrotfish, sea bass, red snapper, surgeon fish, ulua. Symptoms usually appear within a few hours but can be delayed for a day or more and include nausea, vomiting diarrhea, muscle pain, itchiness, dizziness and temperature reversal (hot feels cold and cold feels hot). Symptoms can last for months. Persons who had a previous episode of ciguatera fish poisoning should avoid a second exposure as symptoms will be more severe. Prevention: Avoid large fish (more than 2.5 to 3 kilos [6 lbs]) or fillet of large fish, avoid head, roe, intestines and liver where the toxin is more concentrated.
Scombroid poisoning is the result of improper handling and refrigeration of fish containing high levels of natural occurring histidine (amino acid in protein). Contamination with bacteria will convert histidine to histamine-causing symptoms similar to allergic reactions, which occur very rapidly and include headache, abdominal cramps, diarrhea, itching, flushed face, and paralysis may occur. Scombroid poisoning occurs worldwide and affects fish from the Scombridae family: yellow tuna, mackerel, skipjack, and bonito. It can also affect other species such as herring, bluefish, sardine, anchovy, amberjack, and mahi-mahi. Prevention: Proper handling and immediate refrigeration of catch.
Shellfish poisoning is associated with the algal blooms (red tides) occurring in temperate and tropical areas. Shellfish – oysters, clams, cockles, mussels, crabs, lobsters – filter or ingest toxins produced by dinoflagellates micro-organisms. Each different toxin produces characteristic symptoms:
- Symptoms of diarrheic shellfish poisoning occur about 30 minutes to hours after ingestion and include nausea, vomiting, and diarrhea. Recovery occurs within two to three days.
- Symptoms of neurotoxic shellfish poisoning appear rapidly after ingestion and include tingling of mouth, arms and legs, stomach upset, and severe muscle pain. Recovery occurs within two to three days.
- Symptoms of paralytic shellfish poisoning appear rapidly after ingestion and include nausea, numbness of face arms and legs, headache, loss of coordination and dizziness, in severe cases respiratory failure and paralysis may lead to death.
- Symptoms of amnesic shellfish poisoning occur within 24 hours of ingestion and include vomiting, diarrhea, and disorientation. Permanent short-term memory loss has been observed, and in severe cases seizures, paralysis, and death may occur. Persons with kidney disease are especially vulnerable.
Puffer Fish poisoning (Fugu) is caused by a tetrodotoxin accumulating mainly in the liver, intestines and ovaries of puffer fish, ocean sunfish, globe fish, and porcupine fish. Symptoms appear between six and 20 hours and include profuse sweating, salivation, headache, hypothermia, and neurological symptoms of paralysis and respiratory failure. The mortality rate is very high.
