Shiga toxin genes (stx) harbouring Escherichia coli (STEC) strains were isolated and identified from diarrhoeal patients visiting the Dhaka Hospital of ICDDR,B: Centre for Health and Population Research, Dhaka, Bangladesh. Of the 189 E. coli strains isolated from 775 diarrhoeal stool specimens, 19 harboured stx1, and one isolate was revealed to have amplicons for both stx1 and stx2 by a PCR assay. Sequence analysis of the 349-bp stx1 from representative isolates revealed 100% homology with the sequence of stx1 available in the GenBank. Among the stx1 positive isolates, two harboured the eae but none were positive for hlyA, katP, etpD or saa genes. Fifteen of the 20 stx positive strains could be categorized into 13 non-O157 serogroups while 4 were untypable and one was a rough strain. Most of the STEC strains were resistant to ampicillin, cephalothin, co-trimoxazole, tetracycline, and nalidixic acid. In the Vero cell assay, all the strains were negative for expression of Shiga toxin (Stx). Randomly amplified polymorphic DNA (RAPD) PCR analysis demonstrated genetic diversity. This is one of the first reports to show the presence of STEC in diarrhoeal patients in Bangladesh.

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To estimate the time-dependent transmission potential of primary pneumonic plague (PPP), we analyzed historical records from six outbreaks. Based on contact investigation information (source of infection information) of three outbreaks, we generalized the probability density function of the serial interval with a Gamma distribution using maximum likelihood estimations. Furthermore, we used a likelihood-based approach to estimate effective reproduction numbers at time t, R_t, incorporating records from the remaining three outbreaks by assuming independence within unknown contact networks. According to our estimates, the R_t of PPP during the initial phases of each epidemic were roughly in the order of 1.3 (95% confidence interval (CI): 0.0-4.3) in Oakland, 1.4 (0.0-4.6) in Rangoon and 6.5 (0.0-16.0) in Ecuador. The expected values of R_t were shown to slightly exceed unity, even in latter stages. While declining trends in R_t were observed in Oakland and Ecuador, no such trend was observed in Rangoon. The findings suggest that the three outbreaks investigated could have been accompanied by demographic stochasticity. The statistical usefulness of the transformation procedure, even with a small number of recorded cases available, was demonstrated, and the expected responses to bioterrorism using Yersinia pestis were discussed.

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Two new species of black flies, Simulium (Nevermannia) fruticosum sp. nov. and S. (N.) chiangklangense sp. nov. are described on the basis of samples collected in northern Thailand. These new species are assigned to the feuerborni species-group of the subgenus Simulium (Nevermannia), and are easily distinguished from S. (N.) feuerborni Edwards, the only species of the same group known thus far in Thailand, by their simple cocoon without any anterodorsal projection.

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The effect of mass treatment on questionnaire results in the diagnosis of schistosomiasis mansoni was examined in 267 school children in an endemic area of Tanzania by Kato-Katz analysis of fecal specimens. The questionnaire asked for information about self-diagnosis, abdominal symptoms, blood in stools, history of wild water contact, stool examination and medication for schistosomiasis, and knowledge of the disease. A logistic regression analysis disclosed a significant association between schistosomiasis and "diarrhea" (p ≈ 0.007; odds ratio, 32.0; confidence interval, 2.5 - 403.3) and "abdominal enlargement" (p ≈ 0.003; odds ratio, 15.2; confidence interval, 2.6 - 90.1) among 61 children who had no history of medication for schistosomiasis. The sensitivity and specificity of the model were 86% and 64%, respectively. In contrast, no significant correlation was observed either for the 116 treated children, or for all the 267 children after the mass treatment. We conclude, therefore, that for children who had no history of medication for schistosomiasis, the questionnaire for abdominal manifestations provides reliable information on S. mansoni infection. However, once a child takes medication, the questionnaire becomes unreliable. This observation suggests that immunomodulation by anti-schistosomiasis drugs that kill adult worms exerts an effect on the appearance of abdominal manifestations and might explain the ambiguity of clinical symptoms in chronically infested patients, except in terminal cases. Further studies are required to develop a simple, rapid and cost-effective diagnostic method for monitoring S. mansoni infection after medication in local areas without resort to laboratory-based identification of schistosomiasis.

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