The strategy currently used to control and eliminate measles was reviewed on the basis of the achievement in Americas, especially in the English-speaking Caribbean countries. The author participated in one phase of the strategy; measles follow-up immunization campaign in Belize, and reviewed the achievement of the campaign. Several factors were identified as important factors for the success of mass immunization campaign. According to the review and experience of the strategy and its practice for measles elimination in the Americas, the author discussed the importance of political commitment, enthusiastic community's participation and establishment of effective surveillance system for the success of measles elimination program. Although there are still several obstacles for the development of the measles elimination program to other regions, the most important components are the strong political commitment in each country and international cooperation financially and technically. On this point of view, Japan is able to play an important roll towards measles elimination in Asia.

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To explore the mechanisms of immune responses of host to Toxoplasma gondii (T. gondii) infection in pregnant mice, we evaluated roles of cytokines [interferon gamma (IFN-γ), tumor necrosis factor α (TNF-α), interleukin 6 (IL-6) and interleukin 4 (IL-4)] by measuring mRNAs of these cytokines in placentas, lungs and spleens. The pathogenic effects of time and duration of the Fukaya infection on cytokine mRNA levels in pregnant mice were analyzed. The abundance of mRNAs encoding these cytokines was measured by reverse transcriptase (RT) -PCR at early and late stages of pregnancy in various organs of both susceptible C57BL/6 and resistant BALB/c pregnant mice infected with T. gondii. IFN-γ and TNF-α but not IL-6 or IL-4, were predominant in the immune responses of placentas, lungs and spleens of BALB/c and C57BL/6 mice during T. gondii infection. Levels of IFN-γ and TNF-α mRNA in placentas of early stage pregnant BALB/c mice (infected at one-week pregnancy and examined on day 4 after infection; 1W4D) were higher than those in corresponding C57BL/6 pregnant mice, which might correlate with the fact that higher parasite numbers in placentas and lungs of C57BL/6 mice (infected at one-week pregnancy and examined on day 11 after the Fukaya infection; 1W11D) were observed than those in placentas and lungs of corresponding BALB/c mice, but not correlate with the result of parasite numbers (T. gondii No./mg tissue) in spleens of C57BL/6 (0) and BALB/c (120±56) pregnant mice. In the late stage of pregnancy, levels of IFN-γ and TNF-a did not show definite correlations with T. gondii loads in placentas, lungs and spleens. These results indicate that endogenous IFN-γ and TNF-a of early stage pregnancy may be essential for inhibition of T. gondii growth in some organs (placentas and lungs), but not in spleens, and the mechanisms of genetic influence involved in the susceptibility and resistance to acute T. gondii infection may include several immune responses acting together.

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Three new black fly species, i.e., Simulium (Gomphostilbia) padangense sp. nov., S. (Simulium) sumatraense sp. nov. and S. (S.) minangkabaum sp. nov. are described based on females, males, pupae and mature larvae collected from West Sumatra, Indonesia. S. (G.) padangense is unique within the subgenus Gomphostilbia in having the pupal gill with one much inflated and seven slender filaments. S. (S.) sumatraense and S. (S.) minangkabaum are most closely related to S. (S.) celsum from Java and S. (S.) argentipes from Peninsular Malaysia, respectively.

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We report an annual prevalence of hookworm infection among Nepalese as studied at Parasitology Laboratory of Department of Pathology, Tribhuvan University Teaching Hospital, Kathmandu, Nepal over one decade period (1985-1994). A total of 4, 164 to 9, 440 (average 7, 857) fecal samples were examined each year for the presence of various intestinal parasites. The annual positivity rate for hookworm infection ranged from 3.8 to 10.7 percent. Throughout the study period, a higher incidence of hookworm infection was observed among adults compared with children. Hookworm infection was more common among females compared with their male counterparts except for the year 1989 and 1990. Of the two species of human hookworms, 67.0% were Ancylostorna duodenale while remaining 33.0% were Necator arnericanus.

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Thirty-four strains of Vibrio cholerae O1 serotype Ogawa isolated in Lao People's Democratic Republic in 1995 were examined for their biological behaviour and cholera toxin productivity. Biotyping indicated that the 34 strains belonged to the El Tor biotype. All strains were hemolysin positive and resistant to polymyxin B and cholera phage IV. However, 4 strains were negative for the hemolysin activity as determined by the test tube method, although they were positive for the antigenic activity. Prophage typing identified 31 strains of the Celebes type, including 3 cured Celebes type, and 3 Ubol type. All the strains produced detectable levels of cholera toxin; 15 isolates produced more than 100 ng/ml, 10 strains between 10 and 100 ng/ml and 9 strains less than 10 ng/ml, determined by using AKI medium in a stationary test tube. The maximum production was 200 ng/ml.

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Etiologic bacteria of 135 cases with diarrheal diseases and the healthy carrier rate in 211 individuals were studied in People's Democratic Republic of Lao. Diarrheagenic Escherichia coli, Shigella and Campylobacter were the predominant pathogens isolated. This country does not face the sea, but Vibrio Parahaermolyticus was isolated from 2 cases. Healthy carrier rate of enteropathogenic E. coli as diagnosed by serogroup Class I was 3 times higher than the detection rate in diarrheal patients (10.9% and 3.7%). Healthy carrier rate of Shigella was 4.3%, whereas the detection rate of Shigella in diarrheal patients was 15.4%. The isolation frequencies of enterotoxigenic E. coli and Campylobacter jejuni in the patients and healthy individuals were almost the same. Verotoxin producing E. coli was found in one healthy individual (Toxin type VT1, O-antigen O111). Rotavirus was not detected from the 29 infant diarrhea examined, but detected from 2 adult cases out of 32 examined.

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