Epidemiology and characterization of leptospirosis at an urban and provincial site in Thailand.

Patients with FUOs at the Children's Hospital in Bangkok and the Chao Phya Abhai Bhu Bejhr Hospital in Prachinburi were screened for leptospirosis by blood and urine culture in addition to microagglutination testing of their serum. Animal populations in urban and periurban areas of Bangkok were surveyed for evidence of leptospira infection. Three rural sites near the Prachinburi Provincial Hospital were also surveyed. The rodents' and domestic animals' blood, urine, and/or kidney cell samples were cultured for leptospira. Sera from these animals were also tested for leptospira antibody. The bataviae serovar was the most commonly detected leptospiral agent in both man and animals. Presenting symptoms varied with age with children showing primarily fever, vomiting, headache, abdominal and generalized muscle pain and diarrhea whereas adults had fever, headache, anorexia, muscle pain and constipation. Blood samples from patients suspected of having leptospirosis were tested for antibody by the MAT and cultured in EMJH media. The following serogroups were identified: bataviae, autumanalis, javanica, hebdomadis, and pyrogens. Leptospirosis incidence in humans was much higher in the rainy/flooding year of 1983 compared to the relatively dry year of 1984. Results of our animal surveillance studies indicate that in addition to rats, which have previously been mentioned, dogs, bandicoots, cattle and pigs could be the source of human leptospirosis infection in both urban and provincial locations in Thailand.

Doxycycline prophylaxis for experimental leptospira infection in non-human primates and hamsters.

Doxycycline was effective as a chemoprophylactic agent for experimental Leptospira infection in non-human primates and hamsters. Monkeys injected intraperitoneally with Leptospira bataviae, and receiving only diluent as treatment developed a leptospiremia during the first week and later leptospires were cultured from the cerebrospinal fluid and urine. Monkeys treated daily with oral doxycycline for 10 days beginning one day before infection had a shortened period of detectable leptospiremia, and organisms were never detected in the cerebrospinal fluid or urine. Even an oral dose of doxycycline 2 hours before infection and on day 7 prevented the later infection of the cerebrospinal fluid and urine. In hamsters, doxycycline treatment prevented deaths from acute Leptospira infection and when hamsters were treated daily for 4 or more days, renal infection was prevented. The results of animal studies, the susceptibility of LC0475 and the five other isolates to doxycycline in vitro, and lack of evidence for antibiotic resistance in culture suggests this antibiotic may be useful as a prophylactic drug for high risk groups and an effective treatment for leptospirosis in Thailand.

Sporozoite-induced Plasmodium cynomolgi infections in captive born Macaca fascicularis.

Capability of captive born cynomolgus monkeys to substitute for rhesus in the Plasmodium cynomolgi radical curative antimalarial drug development model was examined. Eighteen monkeys divided into 3 groups were given standard or high doses of sporozoites intravenously. One group of 4 received 0.8 - 1.6 X 10(6) and a second group of 8 received 0.3 - 1.0 X 10(7) sporozoites. The third group of 6 was splenectomized and then received 3.0 - 4.0 X 10(6). The 2 groups of intact monkeys developed a persistent low level parasitemia; however, gametocyte production was poor. The splenectomized group developed a persistent parasitemia with a higher mean, which more closely resembled rhesus parasitemias. A high, post-patent leukocytosis consisting primarily of lymphocytes was observed in this group. Good gametocyte production resulted in the splenectomized group and oocysts were produced from all lots of Anopheles dirus which fed on them. Following clearance of blood forms, relapse potential was demonstrated in the 2 splenectomized monkeys tested. In this study the splenectomized captive born cynomolgus appeared to be capable of supplementing rhesus as an antimalarial drug testing model.