In the detection of parasitic infection, the traditional methods based on microscopy often have low sensitivity and/or specificity compared with the newer, molecular tests. An assay based on real-time PCR and a reagent strip test for detecting circulating cathodic antigen (CCA) have both now been compared with urine filtration and microscopy, in the detection of Schistosoma haematobium infections. Urine samples, obtained from 74 'cases' in areas of Ghana with endemic S. haematobium and 79 'controls' from non-endemic areas, were each checked using the three methods. With the results of the filtration and microscopy taken as the 'gold standard', real-time PCR was found to be 100% specific and 89% sensitive whereas the CCA strips were 91% specific and 41% sensitive. With the samples found to contain > or =50 eggs/10 ml (indicating relatively intense infections), the sensitivities of the PCR and CCA were higher, at 100% and 62%, respectively. As expected, egg counts were negatively correlated with the number of amplification cycles needed, in the PCR, to give a signal that exceeded the background (r=-0.38; P<0.01). Although the real-time PCR and CCA strip tests are very different, both show promise in the detection of S. haematobium infections. The PCR has optimal specificity and high sensitivity but the specificity of the CCA strips and the sensitivity of both tools could still be improved. A more thorough re-evaluation of the sensitivity and specificity of microscopy and these newer diagnostic methods, with an estimation of the cost-effectiveness of each technique, is recommended.

BackgroundThe prevalence of peanut allergy has increased in developed countries, but little is known about developing countries with high peanut consumption and widespread parasitic infections.ObjectiveWe sought to investigate peanut allergy in Ghana.MethodsIn a cross-sectional survey among Ghanaian schoolchildren (n = 1604), data were collected on reported adverse reactions to peanut, peanut sensitization (serum specific IgE and skin reactivity), consumption patterns, and parasitic infections. In a subset (n = 43) IgE against Ara h 1, 2, 3, and 9 as well as cross-reactive carbohydrate determinants (CCDs) was measured by using ImmunoCAP. Cross-reactivity and biological activity were investigated by means of ImmunoCAP inhibition and basophil histamine release, respectively.ResultsAdverse reactions to peanut were reported in 1.5%, skin prick test reactivity in 2.0%, and IgE sensitization (≥0.35 kU/L) in 17.5% of participants. Moreover, 92.4% of those IgE sensitized to peanut (≥0.35 kU/L) had negative peanut skin prick test responses. Schistosoma haematobium infection was positively associated with IgE sensitization (adjusted odds ratio, 2.29; 95% CI, 1.37-3.86). In the subset IgE titers to Ara h 1, 2, 3, and 9 were low (<1.3 kU/L), except for 6 moderately strong reactions to Ara h 9. IgE against peanut was strongly correlated with IgE against CCDs (r = 0.89, P < .0001) and could be almost completely inhibited by CCDs, as well as S haematobium soluble egg antigen. Moreover, IgE to peanut showed poor biological activity.ConclusionsParasite-induced IgE against CCDs might account largely for high IgE levels to peanut in our study population of Ghanaian schoolchildren. No evidence of IgE-mediated peanut allergy was found.

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Disclosure of potential conflict of interest: R. Newton's institution received a grant from AstraZeneca for other works and he personally received travel expenses from AstraZeneca. The rest of the authors declare that they have no relevant conflicts of interest.