RESUMEN
The detection of coronavirus disease 2019 cases represents a significant challenge at the epidemiological level. Limitations exist in effectively detecting asymptomatic cases, achieving good follow-up in hospitals without the infrastructure for reverse transcription-quantitative PCR (RT-qPCR) or in difficult-to-access areas and developing methods with the need for less invasive sampling procedures. Therefore, the present study evaluated the performance of the direct reverse transcription loop-mediated isothermal amplification (RT-LAMP) test for detecting severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in the saliva and nasal samples of asymptomatic individuals belonging to the university population. In addition, this test was also assessed for effectiveness in symptomatic individuals referred from a hospital with poor infrastructure in molecular biology and located outside the urban area. The RT-LAMP assay was compared with the results obtained from the RT-qPCR nasopharyngeal swab test, where the diagnosis was confirmed by lateral flow immunoassay test for rapid antigen detection. A total of 128 samples were analyzed, of which 43% were symptomatic positive individuals, 25% were asymptomatic positive individuals and 32% were SARS-CoV2-negative control individuals. Among positive individuals, no differences were found between the Cq values determined by RT-qPCR. A sensitivity of 96.5% and a specificity of 97.6% was reported for the detection of SARS-CoV-2 in symptomatic individuals by salivary and nasal RT-LAMP, as well as a sensitivity of 100% and a specificity of 97.6% for the detection of SARS-CoV-2 in asymptomatic individuals. These findings indicated that performance of the direct RT-LAMP test using saliva and nasal samples has high sensitivity and specificity, which in turn suggest that it is a viable and reliable alternative for use in epidemiological monitoring.
RESUMEN
BACKGROUND: Worldwide, 130 million persons are estimated to be infected with HCV. Puebla is the Mexican state with the highest mortality due to hepatic cirrhosis. Therefore, it is imperative to obtain epidemiological data on HCV infection in asymptomatic people of this region. The objective of present study was to analyze the prevalence of antibodies and genotypes of hepatitis C virus (HCV) in blood donors from Puebla, Mexico. RESULTS: The overall prevalence was 0.84% (515/61553). Distribution by region was: North, 0.86% (54/6270); Southeast, 1.04% (75/7197); Southwest, 0.93% (36/3852); and Central, 0.79% (350/44234). Ninety-six donors were enrolled for detection and genotyping of virus, from which 37 (38.5%) were HCV-RNA positive. Detected subtypes were: 1a (40.5%), 1b (27.0%), mixed 1a/1b (18.9%), undetermined genotype 1 (5.4%), 2a (2.7%), 2b (2.7%), and mixed 1a/2a (2.7%). All recovered donors with S/CO > 39 were HCV-RNA positive (11/11) and presented elevated ALT; in donors with S/CO < 39 HCV-RNA, positivity was of 30.4%; and 70% had normal values of ALT. The main risk factors associated with HCV infection were blood transfusion and surgery. CONCLUSIONS: HCV prevalence of donors in Puebla is similar to other Mexican states. The most prevalent genotype is 1, of which subtype 1a is the most frequent.
