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.

Canine ehrlichiosis (tropical canine pancytopenia) in Thailand.

An epizootic of canine ehrlichiosis has occurred in military working dogs in Thailand. During the epizootic, 161 cases of ehrlichiosis were identified serologically in a population of 316 dogs, and 54 dogs exhibited clinical signs of disease. The epizootic is being controlled by elimination of ticks, by serologic identification and treatment of carriers with 30 mg/lb body weight/day of tetracycline for 14 days, and by continuous daily prophylactic administration of 3 mg/lb body weight/day of tetracycline. Clinical and serologic recognition of ehrlichiosis among pet dogs in widely separated regions of Thailand suggest that the disease has been endemic in Thailand for an extended time. Under such circumstances it is possible that pet and stray dogs have served as a source of infection for the epizootic in military working dogs.