Materials and methods: A cross-sectional hospital-based study was carried out on 300 participants. Blood samples were obtained. Thick and thin blood films were prepared and viewed using the standard parasitological technique of microscopy. Moreover, data on sociodemographic and environmental variables were obtained using a pre-tested standard questionnaire.
Results: Of the 300 participants examined, a total of 165 (55.0%) were found positive for Plasmodium falciparum with a mean (S.D) parasite density of 1814.70 (1829.117) parasite/μL of blood. The prevalence and parasite density of malaria infection vary significantly (P < 0.05) with age group. Children <5 years old were more likely to have malaria infection and high parasite densities than adults (p < 0.05). Similarly, in relation to gender, males significantly (P < 0.05) had a higher prevalence (60.2%) and mean (S.D) parasite density of malaria infection [2157.73 (1659.570) parasite/μL of blood] compared to females. Additionally, those without formal education had the highest prevalence (73.0%) and mean (S.D) parasite density of infection [2626.96 (2442.195) parasite/μL of blood]. The bivariate logistic regression analysis shows that age group 6-10 (Crude Odds Ratio, COR 0.066, 95% CI: 0.007-0.635), presence of streams/rivers (COR 0.225, 95% CI: 0.103-0.492), distance from streams/rivers within ≤1 km (COR 0.283, 95% CI: 0.122-0.654) and travel to rural area (COR 4.689, 95% CI: 2.430-9.049) were the significant risk factors.
Conclusions: Malaria infection is prevalent in the study area and was greatly influenced by traveling activities from the rural areas to urban centers and vice versa. Multifaceted and integrated control strategy should be adopted. Health education on mosquito prevention and chemoprophylaxis before and during travel to rural areas are essential.
METHODS: Using the recently completed genome sequences from P. malariae, P. ovale and P. knowlesi, a set of 33 candidate cell surface and secreted blood-stage antigens was selected and expressed in a recombinant form using a mammalian expression system. These proteins were added to an existing panel of antigens from P. falciparum and P. vivax and the immunoreactivity of IgG, IgM and IgA immunoglobulins from individuals diagnosed with infections to each of the five different Plasmodium species was evaluated by ELISA. Logistic regression modelling was used to quantify the ability of the responses to determine prior exposure to the different Plasmodium species.
RESULTS: Using sera from European travellers with diagnosed Plasmodium infections, antigens showing species-specific immunoreactivity were identified to select a panel of 22 proteins from five Plasmodium species for serological profiling. The immunoreactivity to the antigens in the panel of sera taken from travellers and individuals living in malaria-endemic regions with diagnosed infections showed moderate power to predict infections by each species, including P. ovale, P. malariae and P. knowlesi. Using a larger set of patient samples and logistic regression modelling it was shown that exposure to P. knowlesi could be accurately detected (AUC = 91%) using an antigen panel consisting of the P. knowlesi orthologues of MSP10, P12 and P38.
CONCLUSIONS: Using the recent availability of genome sequences to all human-infective Plasmodium spp. parasites and a method of expressing Plasmodium proteins in a secreted functional form, an antigen panel has been compiled that will be useful to determine exposure to these parasites.