Anopheles culicifacies, the major vector of malaria in Sri Lanka, and An. subpictus, a secondary vector, exist as species complexes in the country. Among the globally reported five sibling species (A-E) of the An. culicifacies complex, only species B and E have been detected in Sri Lanka. However, all four sibling species (A-D) of the An. subpictus complex present globally are found in Sri Lanka. This article reviews the data on the characteristics of the sibling species of these two main malaria vectors in Sri Lanka and methods for differentiating them, and highlights the importance of understanding the bio-ecological variations among the sibling species in order to develop an effective vector control program in the country. It is proposed that An. culicifacies species E may have evolved from species B in Sri Lanka and then spread to South India. The development of DNA probes suitable for differentiating the sibling species of An. culicifacies and An. subpictus in field studies is identified as a particular priority for future work.

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Immunobiological roles of schistosome eggs during murine experimental infection were investigated with special reference to the induction of basophilic leukocytes. After single- or bisexual infection with Schistosoma mansoni in BALB⁄c mice, splenomegaly and liver granulomas were observed only in bisexual infection in parallel with deposition of mature parasite eggs. Comparison of the kinetics of basophil response revealed a marked increase in number in the bone marrow of mice with bisexual infection at the 7^th week post infection as opposed to a marginal increase in single- sex infections. In the spleen, bimodal response was observed in the basophil responses; a small but repeatable peak at the 4^th week after infection, increasing again at the 8^th week, which corresponded to the initiation and maturation of parasite eggs in the affected organs of infected mice. The same time course was observed for IL-4 production by the splenocytes from mice of bisexual infection. To obtain more concrete evidence of the role of eggs in the induction of basophils, we tested using the intravenous egg injection model. Injection of eggs induced basophilia, and it was accompanied by the up-regulation of IL-4 production in splenocytes from the 8^th day. Basophils induced in this model showed a high level of IL-4 production confirmed by flow cytometry, while faint levels of IL-4 production were observed for CD4⁺ T cells at this time point. In addition, we demonstrate that egg deposition is the trigger of basophil induction and activation in the murine experimental model of S. mansoni infection, which might play an essential role in the initiation of Th1⁄2 conversion during the course of S. mansoni infection in vivo.

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Sophy β-glucan, a type of β-1,3-1,6 glucan produced by a black yeast Aureobasidium pollulans strain AF0-202, is currently approved for use as a health food supplement. The new genotypic avian influenza H5N1 is one of the major emerging infectious diseases causing concern and loss in Vietnam, Asian and several European countries during the 2003-2008 period. We examined the effect of Sophy β-glucan on the immune response against the new H5N1 vaccine made in Vietnam⁄China and H5N2 made in China. As a result, both H5N1 and H5N2 vaccines elicited a significantly high immune response with Sophy β-glucan supplied in drinking water in all the mice tested (2-3 log2 higher HI titer). These vaccines also elicitated ELISA positivity (ELISA (+): seroconversion) 10-20% higher than those used in groups vaccinated without Sophy β-glucan. We conclude that Sophy β-glucan showed an excellent adjuvant effect on H5N1 and H5N2 vaccinations in a mouse model.

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A prevalence study was conducted on Trichomonas vaginalis infection among female sex workers attending the Reproductive Health and Wellness Center of Angeles City, Pampanga in the Central Luzon region of the Philippines. Polymerase chain reaction (PCR) using T. vaginalis-specific primers TV3⁄7 was utilized to detect T. vaginalis in vaginal swabs from the study population. The lower limit sensitivity of T. vaginalis detection by the PCR assay was found to be one trichomonad. The overall prevalence in 377 women was 9.55%. More than half of the study subjects are 23-27 years old. However, the largest proportion of positive cases was found among subjects 18-22 years old, making it the age group with the highest T. vaginalis prevalence (12.84%).

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Four hundred and six soil samples collected from five schoolyards in Mai Trung Commune, Bac Giang Province, Northern Vietnam, from 2005 to 2007 were examined for helminth eggs using a sucrose centrifugal flotation method. The soils around latrines was found to be heavily contaminated with Ascaris sp. eggs. The contamination rate of Ascaris sp. eggs at each school and prevalence of ascariasis among the school children showed a positive correlation (P&It;0.05). This indicated that examination of soil from the area around latrines for Ascaris sp. eggs is a useful method to estimate the prevalence of ascariasis among school children.

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In addition to Dengue virus infection, another mosquito-borne viral infection has become a significant health hazard. After the first domestic case of Chikungunya fever was reported in the Republic of Singapore, the outbreak was brought under control in 18 days. Despite the quick and thorough public health measures including intensive vector control, this country known as a developed island state could not stop the subsequent outbreaks as both domestic and imported cases surged. Our in-depth investigation benefiting from field activities recapitulates the governmental interventions to control the re-emerging infectious disease. We discuss potential factors contributing to the subsequently increased cases in Singapore and then review strategies that other governments may consider in controlling vector-borne infectious diseases in urban areas with transnational movements of people.

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