Viability of Cryptosporidium parvum oocysts in natural waters.

Water-borne transmission of the coccidium Cryptosporidium parvum Tyzzer, 1912 is frequently responsible for outbreaks of human cryptosporidiosis. One of the most important was reported in 1993 in Milwaukee in the United States, where 403,000 cases were recorded. The determination of the percentage of oocysts excystated is the first step in evaluating their viability, but it alone is not sufficient. This percentage depended on the conditions of storage and also the presence of oxidant or disinfectent agents in water. The percentage of excystation is not always related to viability. Therefore, determination of the viability of excysted sporozoites by determining their infectivity for enterocytic Caco2 cell lines in culture provides information essential for evaluating the risk of contaminated drinking water.

[Human babesiosis in 1997]. / La babésiose humaine en 1997.

Human babesiosis is a rare parasitic infection caused by an haemoprotozoan of genus Babesia, transmitted by tick bites. In Europe, the most severe cases are observed in asplenic patients infected by Babesia divergens. Acute intravascular haemolytic syndrome appears rapidly and is responsible for renal failure and is life threatening. Most of the cases have been reported in France. In contrast, Babesia microti babesiosis observed in the United States are less severe than Babesia divergens cases. The major problem raised by babesiosis is the rapidity of the clinical and biological diagnosis. The currently recommended treatment of severe cases consists of a blood exchange followed by clindamycine intraveine use, 25 mg/kg/d in three treatments, until disappearance of parasitemia. Prophylaxis against tick bites should be recommended for asplenic individuals.

ParaSight-F rapid manual diagnostic test of Plasmodium falciparum infection.

The ParaSight(R)-F test is a qualitative diagnostic test of Plasmodium falciparum, which is based on the detection by a monoclonal antibody of a species-specific soluble antigen (histidine-rich protein (HRP-II)) in whole blood and which can be performed without special equipment. A visual reading is given by a polyclonal antibody coupled with dye-loaded liposomes; when positive, a pink line appears. The test has been compared with microscopic examination of thin blood smears and with Quantitative Buffy Coat malaria test (QBC(R) in a single-blind study. A total of 358 patients who had returned to France from malarial areas and consulted their doctor with symptoms or for a routine examination were enrolled in the study; 33 of them were found to have a falciparum malaria infection by the diagnostic test. On the day of consultation, the specificity of the ParaSight(R)-F test was 99% and its sensitivity 94%. The follow-up of infected patients after treatment showed that the test became negative later than the other reference tests. There was no correlation between antigen persistence and the intensity of the ParaSight(R)-F signal or circulating parasitaemia. No cross-reaction was noted for seven malaria cases due to other Plasmodium species. The test was performed quickly (10 tests in 20 minutes), was easy to read, and required minimal space. For cases of imported malaria, the test's specificity and low threshold for detection could make it a valuable adjunct test. However, in its present form, it cannot replace microscopic techniques which are species-specific and quantitative. In endemic areas, the test seems to be very promising by its results and ease of use according to published field studies.