Environmental Contact Risks
Many diseases directly penetrate the intact skin. Wearing shoes or sandals minimizes the risk of acquisition of soil-borne parasites such as hookworms and Strongyloides. Schistosomiasis is an infection caused by water-borne parasites that can penetrate intact skin and can cause significant illness. The results of such infections can be devastating, as in the case of 2 American students who acquired acute schistosomiasis with paraplegia following bathing in a Kenyan river. Schistosoma are widely distributed in Africa, South America, and Asia. Due to the potential severity of illness, travelers visiting areas endemic for schistosomiasis should avoid swimming or bathing in fresh water lakes and streams.
Rabies is a neurologic infection caused by a virus that is most often acquired by the bite of an infected mammal. Rabies acquired by domestic dogs is a rare event in the U.S. but is very prevalent in much of the rest of the world, including most of Asia, Africa, and Latin America. Thirty cases of human rabies have been reported in the United States since 1980. Fourteen (47%) were associated with exposure to dogs and 12 of these were likely acquired outside the United States. A recent case of an American woman who died of rabies following a dog bite while trekking in Nepal illustrates the serious nature of this condition. Rabies is highly endemic in many overseas dog populations.
There are two types of rabies immunizing products:
- Human rabies immune globulin. (HRIG; Cutter Biological, Miles Inc). HRIG is an antirabies immune globulin concentrated by cold ethanol fractionation from plasma of hyperimmunized human donors. HRIG provides rapid, passive immune protection that persists for only a short time (half-life of 21 days) after intramuscular administration.
- Rabies vaccines induce an active immune response with the production of neutralizing antibodies. There are two rabies vaccines licensed for use in the U.S.: Rabies Vaccine, Human Diploid Cell (HDCV; Pasteur-Mérieux), and Rabies Vaccine, Adsorbed (RVA; Michigan Department of Public Health). Both the preexposure regimens of HCDV and RVA are >99% effective when used as recommended. Rabies preexposure vaccine prophylaxis is administered as a 3 shot series over a one month period.
The CDC recommends that rabies preexposure vaccination be offered to persons spending more than 1 month in foreign countries where canine rabies is endemic, or whose activities bring them into frequent contact with potentially rabid dogs, cats, skunks, raccoons, bats, or other species at risk of acquiring rabies. The goal of preexposure preventative Rabies vaccination in travelers is to protect those whose postexposure therapy might be delayed, especially if reliably safe needles or vaccines are not locally available. Although preexposure vaccination does not eliminate the need for additional therapy after a rabies exposure, it simplifies therapy by eliminating the need for HRIG and decreases the number of required post-exposure vaccine doses.
Postexposure rabies vaccination is recommended any time before the onset of symptoms following a suspected animal exposure. The wound should be thoroughly cleaned with soap and water. One half of the HRIG dose should be infiltrated around the wound(s) if anatomically feasible, and the rest should be administered IM in the gluteal area in the previously unvaccinated person in addition to either HDCV or RVA, 1.0 mL, IM (deltoid area), one each on days 0, 3, 7, 14, and 28. In previously vaccinated individuals with a documented history of antibody response to the prior vaccination, HRIG is not indicated, and only two doses of either HDCV or RVA are given on days 0 and 3.