New Protozoa
on the Scene and Causing Trouble:
2 cases of Traveler's
Diarrhea caused by the "recently described" protozoa Cyclospora are
discussed in December's Journal of Travel Medicine. The article describes
Cyclospora as having a worldwide distibution and a high prevalence in tropical
countries, with prolonged self-limiting and relapsing diarrhea, lasting approx.
20 days in each case. "Some reports suggest that the agent is a common
cause of traveler's diarrhea." In each of the cases studied here "the
onset was abrupt, with diarrhea, abdominal cramps, nausea, and loss of
appetite...Both patients acquired the infection in Asia, one in Nepal, and the
other one in Indonesia." (Journal of Travel Medicine, Official Publication
of the International Society of Travel Medicine, Vol. 2, No. 4, December 1995,
pp. 232-234.) According to microbiologist Misha Hasan, the symptoms are similar
to those of Cryptosporidiosis; the mode of transmission is fecal/oral, water,
animals, food or produce; and infection is mostly related to travel, especially
in S.America, Nepal, with a few cases in N. America. Cyclospora is found
commonly in native populations.
News on Cholera Vaccines:
According to the findings of another Journal of Travel Medicine
study, there is to date no hard data supporting a recommendation for all
travelers to vaccinate against cholera. One basis for this is that infection
rates do not vary widely between countries that routinely vaccinate and
countries that do not. The study goes on to point out that "the efficacy of
the traditional inactivated vaccine is only about 50%, but the oral CVD103 HgR
and WC-BS vaccines newly licensed in Europe have an improved efficacy of 80%."
(Journal of Travel Medicine, Official Publication of the International Society
of Travel Medicine, Vol. 2, No. 3, September 1995, pp. 157.)
Crypto
Threat Growing, New Study Shows Iodine/Chlorine Ineffectual:
A joint guidance released by the CDC and the EPA this past summer outlined
the grave new threat posed by the infectious protozoa Cryptosporidium to the
immune-suppressed. Apart from a sturdy immune system, no cure has yet been
found for Cryptosporidiosis, Government tests show that at least half of the
municipal water systems in the country remain contaminated with Crypto even
after the water is treated, and over 87% of surface water in the country is
thought to be contaminated with Crypto. Public awareness of the Crypto threat is
growing, but many may still believe that chemical disinfection (iodine tablets
or chlorine crystals) will protect them from that threat. Several studies have
shown that disinfection is not in fact effective. The latest study is entitled
"Efficacy of Water Purification Tablets and Granules Against
Cryptosporidium Oocysts and Giardia Cysts", dated August, 1995, and
conducted by the Department of Microbiology & Immunology at the University
of Arizona. When tested according to their usage instructions, neither the
iodine product nor the chlorine product worked against Crypto. Though neither
product claims to protect against Crypto, only Giardia or "protozoa",
it is important for people to know exactly which pathogens they are and which
they are not being protected against with any product. With the iodine, "the
tablets were not effective in the inactivation of Cryptosporidium oocysts in
either average or worst case water quality conditions." With the chlorine
granules, "no inactivation of [Crypto] was observed..even after 6 hours of
contact." The Giardia was more responsive than the Crypto to disinfection,
although with both iodine and chlorine, "a longer contact time was required
than recommended by the manufacturer to inactivate 99.9% of the Giardia cysts in
worst case water." This parasite is common to all surface waters in the
United States, Canada and overseas, and effective treatment of drinking water is
needed to prevent its transmission.
Methods of Treatment
Water Filters