B.U. Bridge is published by the Boston University Office of University Relations.

Contact Us

Staff

Bug battle: preventing parasitic infections

I'm traveling overseas in a few weeks and am concerned about parasitic infections. What can I do to prevent contracting something while I am there?

A parasite is an organism, such as a single-cell protozoan or a worm, that survives by living inside another, usually much larger, organism, called the host. Parasites are common in rural Africa, Asia, and South America, but are rare in developed countries because of improved sanitation and other control measures.

You are right to be concerned about developing a parasitic infection when going abroad. People who travel to developing countries can be infected by a parasite, as well as by bacteria, and unknowingly return home with an infection.

In many developing countries, food and water supplies are responsible for most of the parasitic infections that tourists and business travelers contract. Insects, primarily mosquitoes, are also culprits. Surprisingly, in some developing countries, people can contract parasitic infections simply by walking barefoot because hookworm larvae, released in soil, can penetrate the skin.

Parasites can also infect people living in developed countries, including the United States, says Stuart Levitz, M.D., an infectious disease physician at Boston Medical Center and professor of medicine and microbiology at Boston University School of Medicine. Poor sanitation, improper cooking, and contact with cat feces are among some of the more common causes.

"The term parasitic infection is a catch-all," says Levitz. "Each parasite has its own life cycle and its own mode of transmission, and each causes different symptoms." Often, however, people with parasitic infections are asymptomatic.

Malaria, giardia, hookworm, and toxoplasmosis are among the more common parasitic infections throughout the world. It is estimated that hookworms have infected nearly one-half of the world's population, and malaria is one of the most common causes of death worldwide from infectious diseases.

Caused by the bite of an infected mosquito, malaria results in fever, headache, muscle aches, and chills. Four types of malaria exist, and depending on the type, symptoms can include abnormal brain function, mild jaundice, and blackwater fever (a rare complication caused by the rupture of large numbers of red blood cells). Left untreated, malaria can be fatal.

Giardia is one of the more common parasitic infections of the intestine in the United States, especially in places where sanitation is poor. Symptoms are usually mild, and can include nausea, gas, abdominal discomfort, and diarrhea.

Caused by an intestinal roundworm, hookworm infection is characterized by an itchy, flat, raised rash where the larvae have penetrated the skin. In adults, hookworms often cause pain in the upper abdomen, iron-deficiency anemia, and low levels of protein in the blood. Children can suffer from heart failure and widespread tissue swelling because of prolonged blood loss.

Toxoplasmosis, says Levitz, is somewhat common in the United States. People become infected either by eating raw or undercooked meat or through exposure to the parasite via cat feces. Because toxoplasmosis can be transferred to a fetus through the placenta, children can be born with the infection, which may be severe and fatal. Symptoms can include inflammation of the eyes, leading to blindness, jaundice, easy bruising, and convulsions. Acquired after birth, toxoplasmosis is often asymptomatic.

"To prevent or protect against parasitic infections in the United States," says Levitz, "I'd recommend the same measures that protect against bacterial and food-borne infections: washing hands, cooking meat thoroughly, cleaning utensils properly, and filtering water."

Levitz says that people traveling abroad should go to a travelers' clinic to get up-to-date on immunizations and obtain advice about how to protect themselves in certain countries. For example, he notes, parasites may be found in one part of a country but not another, or they may be more prevalent during a certain season. These clinics can help travelers prepare before leaving on their trip, thereby reducing the risk of developing a parasitic infection.

Finally, says Levitz, people who are immunosuppressed -- individuals with HIV/AIDS and other immune deficiencies -- are particularly susceptible to parasitic infections, and he recommends that these individuals speak with their doctor regarding prevention.

"Health Matters" is written in cooperation with staff members of Boston Medical Center. For more information on parasitic infections or other health matters, call 617-638-6767.

8 June 2001
Boston University
Office of University Relations