Immunoregulation in human malaria: the challenge of understanding asymptomatic infection

Asymptomatic Plasmodium infection carriers represent a major threat to malaria control worldwide as they are silent natural reservoirs and do not seek medical care. There are no standard criteria for asymptomatic Plasmodium infection; therefore, its diagnosis relies on the presence of the parasite during a specific period of symptomless infection. The antiparasitic immune response can result in reduced Plasmodium sp. load with control of disease manifestations, which leads to asymptomatic infection. Both the innate and adaptive immune responses seem to play major roles in asymptomatic Plasmodium infection; T regulatory cell activity (through the production of interleukin- 10 and transforming growth factor-β) and B-cells (with a broad antibody response) both play prominent roles. Furthermore, molecules involved in the haem detoxification pathway (such as haptoglobin and haeme oxygenase-1) and iron metabolism (ferritin and activated c-Jun N-terminal kinase) have emerged in recent years as potential biomarkers and thus are helping to unravel the immune response underlying asymptomatic Plasmodium infection. The acquisition of large data sets and the use of robust statistical tools, including network analysis, associated with welldesigned malaria studies will likely help elucidate the immune mechanisms responsible for asymptomatic infection.

Respiratory effects of biomass fuel combustion on rural fish smokers in a Nigerian fishing settlement: a case control study.

Backgroud: The aim was to study the prevalence of respiratory symptoms and assess the lung function of fish smokers in Nigeria. Methods: A case control study was done among fish smokers in Nigeria. Women aged 15 years or older (n=210) involved in fish smoking and equal number of matched controls were interviewed on respiratory symptoms and their peak expiratory flow rate (PEFR) measured. Data was analysed using chi square test, student\'s t-test and odd ratios. Results: Both groups were similar in their personal characteristics. The test group had significantly increased occurrence of sneezing (153; 72.86%), catarrh (159; 75.71%), cough (138; 65.71%) and chest pain (59; 28.10%) compared with the control group, odds ratio (OR) 2.49, 95% confidence interval CI (1.62-3.82), P < 0.001), OR 3.77,95% CI (2.44- 5.85), P < 0.001, OR 3.38, 95% CI (2.22-5.15), P < 0.001, and OR 6.45,95% CI (3.22-13.15), P < 0.001, respectively. The mean PEFR of 321±58.93 L/min among the fish smokers was significantly lower than 400±42.92 L/min among the controls (p = 0.0001). Conclusion: Fish smokers have increased risk of respiratory symptoms and reduced pulmonary function. There is a need for protective equipment and periodic evaluation.