Investigation of the role of Blankaartia acuscutellaris (Acari: Trombiculidae) as a vector of scrub typhus in central Thailand.

Monthly collections of rodents were conducted in Phitsanulok Province, central Thailand in 1993 to investigate the role of the mite Blankaartia acuscurellaris as a vector of scrub typhus. Overall, a total of 41 rodents were collected and examined for the presence of the red colored larvae of B. acuscutellaris and yellow larvae of Leptotrombidium deliense and Ascoshoengastia sp. A total of 787 B. acuscutellaris and 1390 yellow larvae were placed into pools, triturated and isolation of Orientia tsutsugamushi attempted in laboratory mice. The sera of 8 of the collected rodents had elevated antibodies to O. tsutsugamushi indicating active infections; however, O. tsutsugamushi was not isolated from rodent tissues or pools of larvae. The results of this survey suggest that B. acuscutellaris may not be an important vector of scrub typhus, but more studies are needed in endemic areas.

Efficacy of common broad spectrum anthelmintics against hook worm, Ascaris and Trichiuris in Hat Yai district, Songkhla Province, Thailand.

1. The third therapeutic scheme should be used in the hospital. 2. The second and third therapeutic scheme may be used in mass treatment. 3. The 4th-6th therapeutic scheme is to be considered, reviewed, and evaluated. 4. Model and technology of permanent worms control is to be studied. 5. The treatment and control of Ascaris were simple. Cure with low reinfection rate and long reinfection period was remarkable. 6. The prevalence rate and reinfection rate of Trichiuris was high, and not so sensitive to any antelmintics. 7. The reinfection rate in the second group was not superior to the first group and the third group. This revealed no effectiveness of ovicidal and larvicidal on the helminthiasis. 8. Reinfection rate in the third therapeutic scheme was the least group. 9. Toxicity and side effect were not found in any anthelmintics. 10. Broad Spectrum Anthelmintics are necessary in mass treatment or blind treatment.

Scrub typhus in suburban Bangkok: first cases.

Three patients, two of whom had eschars, were admitted with fulminant febrile disease suggestive of scrub typhus. Elevated IgG and IgM to Rickettsia tsutsugamushi were detected in all three by IFA. The cases lived in widely separated areas of western Bangkok where fruit trees are grown and claimed not to have left the areas of their homes during the estimated incubation periods. A field survey collected rodents, treeshrews, and mites fro around the homes of each case. R. tsutsugamushi was isolated from one rat and known vector species of mites were found. These are the first confirmed cases of scrub typhus transmission in Metropolitan Bangkok. It is suggested that typhus incidence around Bangkok may be substantial but has been unreported because of widespread self-medication with antibiotics and the difficulties of laboratory diagnosis.

Rickettsia tsutsugamushi strains found in chiggers collected in Thailand.

R. tsutsugamushi strains found in chiggers collected from 3 different sites throughout Thailand were antigenically characterized. Monotypic infections were observed in 76.7% of the chiggers. Karp was the most predominant strain, followed by TA716, TA763, TA686 and Kato. This study represents the first confirmed report of R. tsutsugamushi infection in 8 different chigger species in Thailand.