Traveler’s diarrhea is characterized by the onset of loose, watery or semi-formed stools, of an urgent nature, accompanied by abdominal cramps. Vomiting may also accompany diarrhea (15% of cases). Symptoms may be preceded by flatulence and abdominal cramping. The illness is usually self-limited lasting 3-4 days.
Traveler’s diarrhea is most commonly caused by bacteria (85%), but can also be caused by parasites (10%) and viruses (5%). The risk of acquiring traveler’s diarrhea is dependent on your travel destination. Countries are classified as low-risk, intermediate-risk and high-risk (see Map). The Centers for Disease Control and Prevention (CDC) estimated that 30-50% of travelers will develop traveler’s diarrhea during a 1- to 2-week stay in high-risk areas.
Risk of traveler’s diarrhea varies seasonally in temperate climates, listed in the dictionary of biology.
- United States
- AustraliaNew Zealand
- northern and western Europe.
- Eastern Europe
- South Africa
- Caribbean Islands
- Middle East
- Central and South America
Ingestion of contaminated food or water is responsible for most cases of traveler’s diarrhea, and most of these are caused by bacteria. A number of different bacteria may cause traveler’s diarrhea:
Enterotoxigenic E. coli (ETEC):
- large inoculum required to produce illness,
- associated with sanitation breakdown,
- common in developing countries,
- symptoms include watery diarrhea and cramps,
- fever, if present, is low-grade.
Enteroaggregative E. coli (EAEC):
- responsible for up to 25% of cases of traveler’s diarrhea,
- symptoms similar to ETEC-associated illness.
- commonly associated with diarrhea in developed countries,
- much more prevalent in developing countries,
- most of Asia is considered high-risk,
- symptoms include blood diarrhea and fever.
- commonly associated with foodborne outbreaks in developed countries,
- infrequent cause of traveler’s diarrhea.
- common cause of traveler’s diarrhea,
- low infectious dose required for illness,
- symptoms include diarrhea (may be bloody), abdominal cramps, and fever.
- Vibrio parahaemolyticus and non-O-group 1 Vibrio cholerae,
- associated with eating raw or partially cooked seafood.
Protozoan parasites account for approximately 10% of cases of traveler’s diarrhea. Onset of illness is usually less abrupt than with bacteria-associated traveler’s diarrhea, and symptoms are often persistent.
The most common parasites responsible for traveler’s diarrhea include:
- intestinal flagellate,
- associated with ingestion of contaminated surface water associated with poor sanitary conditions,
- foodborne outbreaks resulting from contamination of food by infected food-handlers,
- person-to-person transmission occurs due to poor fecal-oral hygiene,
- environmentally resistant cyst form shed in feces,
- incubation period 12-19 days,
- common symptoms include diarrhea, weakness, weight loss and abdominal pain,
- less common symptoms of nausea, vomiting, flatulence and fever,
- illness usually self-limiting, lasting 2-4 weeks.
- common intestinal pathogen worldwide,
- associated with contaminated drinking water and recreational water,
- average incubation period of 7 days,
- watery diarrhea most prominent symptom,
- frequent and copious bowel movement can cause dehydration and weight loss,
- symptoms include nausea, abdominal cramps, vomiting and mild fever,
- environmentally resistant oocysts shed in stool for at least 2 weeks following illness.
- associated with ingestion of contaminated water and food,
- incubation period 2-11 days,
- symptoms include watery diarrhea, fatigue, abdominal cramping, anorexia, weight loss, vomiting, low-grade fever, and nausea,
- illness may last for weeks with episodes of watery diarrhea alternating with constipation,
- environmentally resistant oocysts shed in feces for up to 60 days.
Giardia lamblia, Cryptosporidium parvum and Cyclospora cayetensis are endemic parasites in supplies of drinking water throughout the world. All three have been found in most surface waters with concentration related to the level of fecal pollution. The cysts (Giardia) and oocysts (Cryptosporidium and Cyclospora) are resistant to environmental conditions and disinfectants, although boiling water for 10 minutes is sufficient to kill cysts and oocysts. Additionally, relatively low numbers of cysts and oocysts are required for infection to occur (less than 100 cysts/oocysts).
- developing countries that have poor sanitary conditions,
- Incubation period usually 1 – 4 weeks,
- symptoms include loose stools, abdominal pain and cramping,
- severe form (amoebic dysentery) associated with abdominal pain, bloody stools, and fever,
- in rare cases, parasite invades the liver and forms an abscess.
- protozoan parasite with a world-wide distribution,
- does not have a protective cyst stage,
- symptoms, if present, include diarrhea, abdominal pain and cramping, loss of appetite, weight loss, nausea and fatigue,
- may result as coinfection with pinworm (Enterobius vermicularis).
Although enteric viral infections are responsible for only 5-10% of cases of traveler’s diarrhea, illness does occur and can be fairly debilitating. Nausea and vomiting are the most common symptoms associated with enteric viral infection. Norovirus and rotavirus are responsible for most cases of enteric viral infection.
Considering that 50,000,000 people travel to developing countries each year, and that 30-50% of travelers to high-risk areas become ill during a 1-2 week visit, approximately 50,000 cases of traveler’s diarrhea occur each day. If you are traveling to a high-risk country, take measures to protect yourself and your family from an illness that could not only destroy your vacation, but may also follow you home!