ABSTRACT
Transmission blocking malaria vaccines are aimed to block the development and maturity of sexual stages of parasite within mosquitoes. The vaccine candidate antigens (Pfs25, Pfs48/45, Pfs230) that have shown transmission blocking immunity in model systems are in different stages of development. These antigens are immunogenic with limited genetic diversity. Pfs25 is a leading candidate and currently in phase I clinical trial. Efforts are now focused on the cost-effective production of potent antigens using safe adjuvants and optimization of vaccine delivery system that are capable of inducing strong immune responses. This review addresses the potential usefulness, development strategies, challenges, clinical trials and current status of Plasmodium falciparum sexual stage malaria vaccine candidate antigens for the development of transmission-blocking vaccines.
ABSTRACT
Background & objectives: Malaria is a major public health problem in many states of the country, particularly, in Madhya Pradesh where both Plasmodium vivax and P. falciparum are endemic. Although many studies have been conducted to investigate risk factors for malaria, but only a few have examined household and socio-economic risk factors. The present study was, therefore, undertaken to explore the relationship of different socio-demographic, socio-economic and behavioural risk factors with malaria prevalence in tribal areas of Madhya Pradesh, India. Methods: This study was undertaken in all 62 villages of Bargi Primary Health Centre from May 2005 to June 2008. These villages comprised 7117 households with an average family size of five members. fortnightly fever surveys were conducted in all villages to assess prevalence of malaria infection in the community. The distinct univariate and multivariate logistic regression models were fitted on the data set. Results: The important socio-demographic risk factors like age of household head, social group, occupation and family size; socio-economic factors like type of walls of house, place of drinking water source, irrigated land, cash crop; and behavioural variables like place of sleeping, use of bed nets, etc. were found significantly associated with malaria in univariate analyses. in multivariate analyses only social groups, family size, type of walls of house, and place of sleeping had strong significant association with prevalence of malaria. Interpretation & conclusions: The study shows that in tribal areas where people are living in poor quality of houses with no proper use of preventive measures, malaria is firmly established. We conclude that community based interventions which bring improvement in standard of living, access to healthcare facilities and health awareness, will have a significant impact on malaria prevention in these areas.
ABSTRACT
Background: Dengue and chikungunya present with very similar signs and symptoms in the initial stage of illness and so it is difficult to distinguish them clinically. Both are transmitted by Aedes aegypti and Aedes albopictus mosquitoes. This study was conducted with the aim to explore the co-circulation of dengue and chikungunya viruses in central India. Materials and methods: Samples from suspected dengue cases were subjected to dengue immunoglobulin M (IgM) enzyme-linked immunosorbent assay (ELISA) and dengue-negative samples were tested with chikungunya-specific IgM ELISA. The samples collected in acute phase of illness were tested by nested reverse transcription polymerase chain reaction (nRT-PCR). Chikungunya virus (CHIKV) sequences were analysed to determine their genotype. Results: Of 138 samples screened for dengue, 21 (15.2%) were positive, and of 119 samples screened for chikungunya, 13 (10.9%) were positive. Dengue viruses 1 and 4 were found co-circulating with chikungunya virus in Jabalpur, central India. The chikungunya virus detected belonged to the East Central South African genotype. Conclusion: Accurate and timely diagnosis would help in patient management and use of resources. It is advocated to simultaneously test samples for these two diseases in endemic areas. This will also aid in understanding the epidemiology of chikungunya.