Objectives: Human T cell leukemia virus type-I (HTLV-I) is a causative agent of human T-cell leukemia and HTLV-I associated myelopathy (HAM/TSP). HTLV-I carriers are often infected vertically, especially via mother's milk. Since 1985, clinical measures have been adopted at a hospital in Okinawa to prevent vertical infections.
Methods: We examined HTLV-I antibodies in all of the women (total 11, 506) who gave birth after 24 gestational weeks at a hospital on the Okinawa main island from January 1985 to December 1999.
Results: The positive rate among all pregnant women was always higher than that among primipara alone. Both figures decreased over the period studied, but the primiparity rate (36-39%) did not change significantly. The percentage of HTLV-I positive primipara pregnant women among the HTLV-I positive total was close to the primiparity rate from 1985 to 1988, but it was considerably lower than the overall primiparity rate thereafter (22-26%).
Conclusions: Preventive measures against HTLV-I infection did not contribute to the decrease in HTLV-I positive mothers before 1999 because these measures were adopted from 1985, and so there must be other reasons for the decrease in HTLV-I positive rate. Further studies on social factors and by year of birth are needed to identify factors influencing HTLV-carrier ratios among pregnant women.

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An in vitro infection system of Trypanosoma cruzi and HeLa cells was used to measure the anti-T. cruzi activities of various calcium antagonists classified into dihydropyridines, diphenylalkylamines, and benzothiazepines and of allopurinol and benznidazole as medium and highly effective reference compounds, respectively. Six dihydropyridines (10 μM each), i. e. nifedipine, nicardipine, nimodipine, nisoldipine, nitrendipine, and amlodipine, decreased the rates of infection of HeLa cells from 11.7% (control) to 5.8, 0.9, 1.2, 3.6, 5.9, and 1.7%, respectively. Nicardipine and amlodipine were highly toxic to HeLa cells, causing detachment of cells from coverslips. Nimodipine was thus the most effective inhibitor tested against T. cruzi infection in HeLa cells. Verapamil and gallopamil (diphenylalkylamines), diltiazem and midazolam (benzothiazepines), and allopurinol (positive control) were less effective than nimodipine. IC₅₀ values, the concentrations of compounds that elicited a 50% reduction in the infection rates of HeLa cells, were 2.5, 2.6, 1.3, 2.1, and 1.7 μM for nicardipine, nimodipine, amlodipine, verapamil, and benznidazole, respectively, while the values for nifedipine, diltiazem, and allopurinol were much higher. Nicardipine, amlodipine, and verapamil again showed significant cytotoxicities to HeLa cells. When Swiss 3T3 fibroblasts replaced HeLa cells, nimodipine markedly lowered the host-cell-infection rate, with an IC₅₀ value of 8.3 nM. Thus, nimodipine is expected to be a highly effective anti-T. cruzi lead compound, with low cytotoxicity to mammalian cells. Structural formulas of nimodipine and nicardipine in relation to their low and high cytotoxicities, respectively, against HeLa cells are discussed.

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Forty-five known species of Simulium Latreille s. l. in Thailand are listed, and keys to subgenera and species within each subgenus are provided for adults, pupae and mature larvae.

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From 1998 to 2001, using questionnaires, we surveyed the use of travel vaccines among Japanese expatriates in developing countries. The percentage of those using more than one type of travel vaccine before departure increased significantly (45.6% in 1998 to 53.4% in 2001 (p<0.001)). In regions such as tropical Africa and South Asia, vaccination rates were high. But the increase was most noticeable in East Asia, the Middle East, and Latin America. Vaccinations against hepatitis A, hepatitis B, and tetanus were high throughout the developing countries. Vaccinations against yellow fever and Japanese encephalitis were high in endemic regions. Vaccination rates were slightly higher for typhoid fever in South Asia and tropical Africa than that in other areas. Vaccination rates for cholera, however, showed yearly declines. These trends seem to reflect a growing awareness among expatriates of the benefits of travel vaccines. Even so, nearly half of those living the countries have not received sufficient vaccination, indicating a need for further education.

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The detection rate of rotaviruses from diarrheal stools in Lao People's Democratic Republic (Lao PDR) was studied in the period from 1994 to 2003. Rotavirus antigen was detected using latex agglutination kit. The average detection rate was 2.4%, or 18 of 738 cases examined in total. Rotavirus was not detected from 175 cases examined in 1995, 1998, 2000 and 2003, but 8 of 85 cases (9.4%) examined in 1997 were positive for rotavirus. The detection rate was 6.0% in the age group younger than 2 years and 0.6% in the age group older than 2 years. These detection rates were markedly lower than those in neighboring countries such as Vietnam and Thailand.

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