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.

Sensitivity and specificity of parallel or serial serological testing for detection of canine Leishmania infection

In Brazil, human and canine visceral leishmaniasis (CVL) caused by Leishmania infantum has undergone urbanisation since 1980, constituting a public health problem, and serological tests are tools of choice for identifying infected dogs. Until recently, the Brazilian zoonoses control program recommended enzyme-linked immunosorbent assays (ELISA) and indirect immunofluorescence assays (IFA) as the screening and confirmatory methods, respectively, for the detection of canine infection. The purpose of this study was to estimate the accuracy of ELISA and IFA in parallel or serial combinations. The reference standard comprised the results of direct visualisation of parasites in histological sections, immunohistochemical test, or isolation of the parasite in culture. Samples from 98 cases and 1,327 noncases were included. Individually, both tests presented sensitivity of 91.8% and 90.8%, and specificity of 83.4 and 53.4%, for the ELISA and IFA, respectively. When tests were used in parallel combination, sensitivity attained 99.2%, while specificity dropped to 44.8%. When used in serial combination (ELISA followed by IFA), decreased sensitivity (83.3%) and increased specificity (92.5%) were observed. Serial testing approach improved specificity with moderate loss in sensitivity. This strategy could partially fulfill the needs of public health and dog owners for a more accurate diagnosis of CVL.

A study of asymptomatic bacteriuria in Egyptian school-going children.

Background: Urinary tract infections (UTI) are a common and important clinical problem in childhood. Upper urinary tract infections (i.e., acute pyelonephritis) may lead to renal scarring, hypertension, and end-stage renal disease. Despite the presence of simple and reliable methods of preliminary screening of children's urine, urinary tract infection continues to be under diagnosed. Objectives: The aim of this study was to establish prevalence rates of significant bacteriuria in asymptomatic school children by simple urine tests in comparison to standard urine culture techniques in Giza, Egypt. Patients and methods: A total of 1000 apparently healthy school going children (6-12) years, 552 boys (55.2%) and 448 girls (44.8%), were enrolled in this cross-sectional prevalence survey. Results: Overall prevalence of significant bacteriuria was 6%. Higher prevalence occurred in girls (11.4%) than boys (1.6%). Escherichia coli was isolated in 35(58%) cases (3 boys and 32 girls), Staph. aureus in 13 (22%) cases (3 boys and 10 girls), Enterobacter in 6 girls (10%), Kelbsiella pneumoniae in 3 boys (5%) and Proteus vulgaris in 3 girls (5%) Conclusion: Asymptomatic bacteriurea could be detected by urine screening program at school age. Overall prevalence of significant bacteriuria was 6%, with predominance in girls than boys.