Differential T-cell responses to a chimeric Plasmodium falciparum antigen; UB05-09, correlates with acquired immunity to malaria.

The development of a sterilizing and cost-effective vaccine against malaria remains a major problem despite recent advances. In this study, it is demonstrated that two antigens of P. falciparum UB05, UB09 and their chimera UB05-09 can serve as protective immunity markers by eliciting higher T-cell responses in malaria semi-immune subjects (SIS) than in frequently sick subjects (FSS) and could be used to distinguish these two groups. UB05, UB09 and UB05-09 were cloned, expressed in E. coli, purified and used to stimulate PBMCs isolated from 63 subjects in a malaria endemic area, for IFN-γ production, which was measured by the ELISpot assay. The polymorphism of UB09 gene in the malaria infected population was also studied by PCR/sequencing of the gene in P. falciparum field isolates. All three antigens were preferentially recognized by PBMCs from SIS. IFN-γ production induced by these antigens correlated with the absence of fever and parasitaemia. UB09 was shown to be relatively well-conserved in nature. It is concluded that UB05, UB09 and the chimera UB05-09 posses T-cell epitopes that are associated with protection against malaria and could thus be used to distinguish SIS from FSS eventhough acute infection with malaria has been shown to reduce cytokine production in some studies. Further investigations of these antigens as potential diagnostic and/or vaccine candidates for malaria are indicated.

The incidence of feco-oral parasites in street-food vendors in Buea, south-west region Cameroon.

BACKGROUND: The street-food industry lacks legal recognition, it operates in unstable and precarious conditions, involving women and men with minimal or no knowledge of hygienic food handling practices. Infective eggs, bacteria, toxins and cysts of faecal orally transmissible parasites are common agents responsible for food contamination in developing countries. OBJECTIVE: To determine the incidence of digestive faecal-oral parasites among street-food vendors in Buea, South-west region of Cameroon, METHODS: From March to May 2009, physical and laboratory analysis of stool samples of 150 randomly selected street-food vendors, residing in four different zones in the municipality were carried out. Information on environmental and personal hygiene was also collected. RESULTS: Results revealed that 56.7% of the sampled population was infected with faecal-oral parasites. The major faecal-oral parasites detected in stool samples were: Entamoeba coli (14.0%), Entamoeba histolytica (12.67%), Ascaris lumbricoides (11.33%), Ankylostoma duodenalis (10.67%). Childcare activities, lack of deworming, poor personal hygiene, poor sanitary and toilet facilities, were factors promoting the spread of faecal-oral infections. CONCLUSION: Food vendors should be educated on personal hygiene and safe food handling measures. Regulatory procedures on environmental hygiene and regular medical and paramedical follow up of food vendors should be enforced.