ABSTRACT
BACKGROUND: Self-collection of nasal swabs for the detection of SARS-CoV-2 RNA by reverse transcription-polymerase chain reaction (RT-PCR) would considerably increase the testing capability and decrease the risk of transmission among healthcare workers (HCW) and the use of personal protective equipment (PPE). OBJECTIVES: This study aimed to evaluate the performance of self-collected nasal swabs compared with professionally collected nasopharyngeal (NP) swabs for detection of SARS-CoV-2 RNA by RT-PCR. MATERIALS AND METHODS: We performed a cross-sectional study where the suspected cases of coronavirus disease 2019 (COVID-19) were instructed about the self-collection of nasal swabs from their mid-turbinate. The results were compared to a nasopharyngeal swab collected by a trained healthcare worker in the same patient at the same sitting. RESULTS: We enrolled 100 participants, of which, 69 (69%) were male and 31 (31%) were female. The median age of the study participant was 36 years. Of the participants, 58 (58%) were symptomatic, and the commonest clinical presentation was cough, which was present in 42 (42%) participants. Out of 100 samples, 31 (31%) professionally collected nasopharyngeal swabs and 28 (28%) self-collected nasal swabs were positive for SARS-CoV-2 by RT-PCR. Out of 31 professionally collected positive samples, three samples were negative in self-collection. Out of 28 self-collected positive samples, no sample was negative in the professional collection. The sensitivity and specificity of self-collected nasal swabs compared to professionally collected nasopharyngeal swabs were 90.32% and 100.00%, respectively. The sensitivity of self-collected nasal was 100% when the cycle threshold (Ct) value of the professionally collected NP swab was less than 30. CONCLUSION: Our study showed that self-collected nasal swabs' sensitivities were similar to professionally collected NP swabs with a high viral load (low Ct value). Hence, this method could be used when the patient is symptomatic and come to the health providers in the early stage of COVID-19 illness.
ABSTRACT
OBJECTIVE: Bangladesh is a high tuberculosis burden country. It is always challenging to diagnose active pulmonary tuberculosis (PTB) cases in rural areas where the setting up of conventional microscopic and cultural diagnostic tools is difficult. The objective of the present study is to find a feasible, reliable and easily accessible alternative diagnostic approach for PTB in the rural areas of Bangladesh. METHODS: A total of 86 sputum samples were collected from clinically suspected PTB patients of Anantapur village, an underdeveloped remote area of Netrokona district, Bangladesh. Sputum samples were screened by Ziehl-Neelsen (Z-N) and fluorescence staining methods and were categorized as smear-positive active PTB cases (n=50) and smear-negative controls (n=36); then the performance of three popular immunological tests were evaluated, including ICT, ELISA and Mantoux tests (MT). RESULTS: The sensitivity of ICT, ELISA, and MT (10mm induration size) was 68%, 84% and 96%, respectively, and the specificity of these tests was 94.4%, 80.6% and 52.8%, respectively. When the cut-off size of induration in MT was changed from 10 to ⩾15mm, the sensitivity and specificity of MT became 92% and 83.3%, respectively. It was also found that the interpretation of MT was not significantly affected by BCG vaccination when ⩾15mm induration was taken as a cut-off value. CONCLUSION: Considering the resource-constraints of rural and remote areas, the Mantoux test could be an alternative tool for the diagnosis of active PTB.
