Diagnostic Performance of Self-Collected Saliva Versus Nasopharyngeal Swab for the Molecular Detection of SARS-CoV-2 in the Clinical Setting.

Coronavirus disease 19 (COVID-19)-caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-has spread rapidly around the world. The global shortage of equipment and health care professionals, diagnostic cost, and difficulty in collecting nasopharyngeal swabs (NPSs) necessitate the use of an alternative specimen type for SARS-CoV-2 diagnosis. In this study, we investigated the use of saliva as an alternative specimen type for SARS-CoV-2 detection. Participants presenting COVID-19 symptoms and their contacts were enrolled at the COVID-19 Screening Unit of Dhaka Hospital of the International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), from July to November 2020. Paired NPS and saliva specimens were collected from each participant. Reverse transcription-quantitative PCR (RT-qPCR) was performed to detect SARS-CoV-2. Of the 596 suspected COVID-19-positive participants, 231 (38.7%) were detected as COVID-19 positive by RT-qPCR from at least 1 specimen type. Among the positive cases, 184 (79.6%) patients were identified to be positive for SARS-CoV-2 based on NPS and saliva samples, whereas 45 (19.65%) patients were positive for SARS-CoV-2 based on NPS samples but negative for SARS-CoV-2 based on the saliva samples. Two (0.5%) patients were positive for SARS-CoV-2 based on saliva samples but negative for SARS-CoV-2 based on NPS samples. The sensitivity and specificity of the saliva samples were 80.3% and 99.4%, respectively. SARS-CoV-2 detection was higher in saliva (85.1%) among the patients who visited the clinic after 1 to 5 days of symptom onset. A lower median cycle threshold (CT) value indicated a higher SARS-CoV-2 viral load in NPS than that in saliva for target genes among the positive specimens. The study findings suggest that saliva can be used accurately for diagnosis of SARS-CoV-2 early after symptom onset in clinical and community settings. IMPORTANCE As the COVID-19 pandemic erupted, the WHO recommended the use of nasopharyngeal or throat swabs for the detection of SARS-CoV-2 etiology of COVID-19. The collection of NPS causes discomfort because of its invasive collection procedure. There are considerable risks to health care workers during the collection of these specimens. Therefore, an alternative, noninvasive, reliable, and self-collected specimen was explored in this study. This study investigated the feasibility and suitability of saliva versus NPS for the detection of SARS-CoV-2. Here, we showed that the sensitivity of saliva specimens was 80.35%, which meets the WHO criteria. Saliva is an easy-to-get, convenient, and low-cost specimen that yields better results if it is collected within the first 5 days of symptom onset. Our study findings suggest that saliva can be used in low-resource countries, community settings, and vulnerable groups, such as children and elderly people.

An outbreak of classical swine fever in pigs in Bangladesh, 2015.

In a group of 22 healthy pigs aged between 4 and 6 months, 2 pigs became ill with high fever, complete anorexia, cough and abnormal swaying movements on 22 June 2015. One of them died on June 24 and the second died on July 3. Shortly after, the remaining pigs also fell ill and died from the same illness by 10 August 2015. We investigated the aetiology, epidemiological and clinical features of the outbreak. We recorded the clinical signs and symptoms for each pig with the date of onset of illness. Veterinarians conducted post-mortem examinations on the 12 dead pigs, they collected tissue samples from the dead pigs and placed them in a tube containing 1 mL of nucleic acid extraction buffer (lysis buffer). We tested all the tissue samples by real-time reverse transcription polymerase chain reaction (rRT-PCR) to detect classical swine fever virus (CSFV) because the animals' symptoms matched those of this disease. We also conducted a phylogentic analysis of the nucleotide sequence of the E2 gene segment of CSFV detected in a lung tissue sample. The attack rate (22/22) and the case fatality were 100%. The predominant symptoms of the disease included high fever, cough, diarrhoea and swaying movements of the hind legs prior to death. Of the 12 pigs tissue samples tested, all had evidence of the presence of CSFV RNA by rRT-PCR. The phylogenetic analysis indicated that the virus belongs to genotype 2.2, which is closely related to CSFV genotype 2.2 reported in India. Our investigation suggests that CSF is circulating in pigs, posing a risk for communities in Bangladesh that rely on pigs for economic income and dietary protein. Future research could focus on estimating the disease and economic burden of CSFV in pig rearing areas to determine if interventions might be warranted or cost-effective.