Background: In Ghana, preschool aged children (PSAC) are at risk of intestinal schistosomiasis and are living in need of praziquantel treatment. To better assess the infection burden within this vulnerable demographic group, we have provided a comparative assessment of the prevalence of Schistosoma mansoni in preschool aged children by urine circulating cathodic antigen (CCA) dipsticks, real-time PCR Taqman® faecal assays and Kato-Katz coproscopy. Methods: In all, 190 preschool aged children were sampled from three endemic communities (viz. Tomefa, Torgahkope/Adakope, and Manheam) around Weija dam, Southern Ghana. Fresh stool and urine samples were collected from all participants for diagnosis. Results: Among all the three communities, the urine-CCA assay recorded the highest prevalence values of 90.5% (95% CI 80.4-96.4), 87.9% (95% CI 76.7-95), and 81.2% (95% CI 69.9-89.6) in Tomefa, Torgahkope/Adakope, and Manheam respectively. Prevalence by real-time PCR was 50% (95% CI 35.5-64.5), 8% (95% CI 2.2-19.2) and 16.7% (95% CI 8.3-28.5), while by Kato-Katz was 55.6% (95% CI 42.5-68.1), 8.6% (95% CI 2.9-19) and 11.6% (95% CI 5.1-21.6) respectively. Children aged 1 year and over were found to be positive with the urine-CCA assay; by the ages of 3-4, over 50% were urine-CCA patent. The sensitivity and specificity of the POC-CCA dipsticks, when compared against the combined results of Kato-Katz/TaqMan results was found to be 84.1% (95% CI = 72.7-92.1) and 12.9% (95% CI = 6.6-22) respectively.
Background Simulium damnosum sensu lato (s.l.) blackflies transmit Onchocerca volvulus, a filarial nematode that causes human onchocerciasis. Human landing catches (HLCs) is currently the sole method used to estimate blackfly biting rates but is labour-intensive and questionable on ethical grounds. A potential alternative is to measure host antibodies to vector saliva deposited during bloodfeeding. In this study, immunoassays to quantify human antibody responses to S. damnosum s.l. saliva were developed, and the salivary proteome of S. damnosum s.l. was investigated. Methodology/Principal findings Blood samples from people living in onchocerciasis-endemic areas in Ghana were collected during the wet season; samples from people living in Accra, a blackfly-free area, were considered negative controls and compared to samples from blackfly-free locations in Sudan. Blackflies were collected by HLCs and dissected to extract their salivary glands. An ELISA measuring anti-S. damnosum s.l. salivary IgG and IgM was optimized and used to quantify the humoral immune response of 958 individuals. Both immunoassays differentiated negative controls from endemic participants. Salivary proteins were separated by gel-electrophoresis, and antigenic proteins visualized by immunoblot. Liquid chromatography mass spectrometry (LC–MS/MS) was performed to characterize the proteome of S. damnosum s.l. salivary glands. Several antigenic proteins were recognized, with the major ones located around 15 and 40 kDa. LC–MS/MS identified the presence of antigen 5-related protein, apyrase/nucleotidase, and hyaluronidase. Conclusions/Significance This study validated for the first time human immunoassays that quantify humoral immune responses as potential markers of exposure to blackfly bites. These assays have the potential to facilitate understanding patterns of exposure as well as evaluating the impact of vector control on biting rates. Future studies need to investigate seasonal fluctuations of these antibody responses, potential cross-reactions with other bloodsucking arthropods, and thoroughly identify the most immunogenic proteins.
Reactive case detection (RACD) is the screening of household members and neighbors of index cases reported in passive surveillance. This strategy seeks asymptomatic infections and provides treatment to break transmission without testing or treating the entire population. This review discusses and highlights RACD as a recommended strategy for the detection and elimination of asymptomatic malaria as it pertains in different countries. Relevant studies published between January 2010 and September 2022 were identified mainly through PubMed and Google Scholar. Search terms included “malaria and reactive case detection”, “contact tracing”, “focal screening”, “case investigation”, “focal screen and treat”. MedCalc Software was used for data analysis, and the findings from the pooled studies were analyzed using a fixed-effect model. Summary outcomes were then presented using forest plots and tables. Fifty-four (54) studies were systematically reviewed. Of these studies, 7 met the eligibility criteria based on risk of malaria infection in individuals living with an index case < 5 years old, 13 met the eligibility criteria based on risk of malaria infection in an index case household member compared with a neighbor of an index case, and 29 met the eligibility criteria based on risk of malaria infection in individuals living with index cases, and were included in the meta-analysis. Individuals living in index case households with an average risk of 2.576 (2.540–2.612) were more at risk of malaria infection and showed pooled results of high variation heterogeneity chi-square = 235.600, (p < 0.0001) I2 = 98.88 [97.87–99.89]. The pooled results showed that neighbors of index cases were 0.352 [0.301–0.412] times more likely to have a malaria infection relative to index case household members, and this result was statistically significant (p < 0.001). The identification and treatment of infectious reservoirs is critical to successful malaria elimination. Evidence to support the clustering of infections in neighborhoods, which necessitates the inclusion of neighboring households as part of the RACD strategy, was presented in this review.
COVID-19 caused by the SARS-CoV-2 was declared a global pandemic by the World Health Organization in March 2020. Classical symptoms associated with the infection include fever, cough, chills, headache, and muscle aches amongst others. To effectively diagnose the infection and contain its spread, efficient diagnostic tools are required. The current gold standard for the confirmation of SARS-CoV-2 infection is RT-PCR, this protocol outlines procedures for the isolation and amplification of SARS-CoV-2 RNA from Nasopharyngeal specimens using the Zymo Quick-RNA Viral Kit and Allplex 2019nCoV Assay Kit respectively.
With over 400 million HBV infections, viral hepatitis B remains a global public health concern. Diagnosis is primarily based on an immunological assay approach, which utilizes the Hepatitis B surface antigen in detection amongst other markers. This method, however, has several limitations which include the inability to detect mutation in the viral genome resulting in diagnostic escape and low antigen titers in study samples. Using an alternative approach, which is the molecular diagnostic technique such as real-time polymerase chain reaction (RT-PCR) would circumvent the limitations of immune detection. This protocol, thus, provides a step-by-step process of HBV diagnosis using RT-PCR which is a sensitive tool for diagnosis. The steps involved include sample collection and preparation, nuclei acid isolation, HBV detection and quantification using RT-PCR as well as the interpretation of results. This protocol combines the high nuclei acid yield from isolation using Zymo Quick DNA Mini-prep Kit and Bosphore HBV Quantitative Kit for amplification of HBV DNA. The Bosphore HBV Quantitative Kit has a low detection limit of 1×101 IU/ml and with a turn-around time of less than 4 hours when combined with Zymo Quick DNA Mini-prep Kit. The nucleic acid isolated in this protocol can be amplified using the Bosphore HBV Quantitative kit on several thermocyclers, which makes the protocol robust, cost-efficient, and cost-effective in resource-scarce areas.
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