Pooling Nasopharyngeal Swab Specimens to Increase Testing Capacity for SARS-CoV-2.

The recent emergence of SARS-CoV-2 has led to a global pandemic of unprecedented proportions. Current diagnosis of COVID-19 relies on the detection of SARS-CoV-2 RNA by reverse transcription polymerase chain reaction (RT-PCR) in upper and lower respiratory specimens. While sensitive and specific, these RT-PCR assays require considerable supplies and reagents, which are often limited during global pandemics and surge testing. Here, we show that a nasopharyngeal swab pooling strategy can detect a single positive sample in pools of up to 10 samples without sacrificing RT-PCR sensitivity and specificity. We also report that this pooling strategy can be applied to rapid, moderate complexity assays, such as the BioFire COVID-19 test. Implementing a pooling strategy can significantly increase laboratory testing capacity while simultaneously reducing turnaround times for rapid identification and isolation of positive COVID-19 cases in high risk populations.

Plasmodium interspecies interactions during a period of increasing prevalence of Plasmodium ovale in symptomatic individuals seeking treatment: an observational study.

BACKGROUND: The epidemiology and severity of non-falciparum malaria in endemic settings has garnered little attention. We aimed to characterise the prevalence, interaction, clinical risk factors, and temporal trends of non-falciparum Plasmodium species among symptomatic individuals presenting at health-care facilities in endemic settings of Kenya. METHODS: We diagnosed and analysed infecting malaria species (Plasmodium falciparum, Plasmodium ovale curtisi, Plasmodium ovale wallikeri, and Plasmodium malariae) via PCR in clinical samples collected between March 1, 2008, and Dec 31, 2016, from six hospitals located in different regions of Kenya. We recruited patients aged 6 months or older who presented at outpatient departments with symptoms of malaria or tested positive for uncomplicated malaria by malaria rapid diagnostic test. Descriptive statistics were used to describe the prevalence and distribution of Plasmodium species. A statistical model was designed and used for estimating the frequency of Plasmodium species and assessing interspecies interactions. Mixed-effect linear regression models with random slopes for each location were used to test for change in prevalence over time. FINDINGS: Samples from 2027 symptomatic participants presenting at care facilities were successfully analysed for all Plasmodium species. 1469 (72·5%) of the samples were P falciparum single-species infections, 523 (25·8%) were mixed infections, and only 35 (1·7%) were single non-falciparum species infections. 452 (22·3%) were mixed infections containing P ovale spp. A likelihood-based model calculation of the population frequency of each species estimated a significant within-host interference between P falciparum and P ovale curtisi. Mixed-effect logistic regression models identified a significant increase in P ovale wallikeri (2·1% per year; p=0·043) and P ovale curtisi (0·7% per year; p=0·0002) species over time, with a reciprocal decrease in P falciparum single-species infections (2·5% per year; p=0·0065). The frequency of P malariae infections did not significantly change over time. Risk of P falciparum infections presenting with fever was lower if co-infected with P malariae (adjusted odds ratio 0·43, 95% CI 0·25-0·74; p=0·0023). INTERPRETATION: Our results show a prevalence of non-falciparum species infections of 27·5% among symptomatic individuals presenting at care facilities, which is higher than expected from previous cross-sectional surveys. The proportion of infections with P ovale wallikeri and P ovale curtisi was observed to significantly increase over the period of study, which could be due to attenuated responsiveness of these species to malaria drug treatment. The increase in frequency of P ovale spp could threaten the malaria control efforts in Kenya and pose increased risk of malaria to travellers. FUNDING: Armed Forces Health Surveillance Branch and its Global Emerging Infections Surveillance Section.

An analysis of trehalose, glycerol, and mannitol accumulation during heat and salt stress in a salt marsh isolate of Aureobasidium pullulans.

Polyhydroxy compounds from Aureobasidium pullulans exposed to stress treatments of heat, salt, and simultaneous heat and salt were isolated, identified, and quantified. Results from both thin-layer chromatography (TLC) and high performance liquid chromatography (HPLC) showed that concentrations of trehalose, mannitol, and glycerol increased under stress conditions that induce osmotic- and thermotolerance in A. pullulans. The cellular concentration of trehalose increased in heat-stressed and in simultaneously heat- and salt-stressed cells but not in cells subjected to salt stress alone. Mannitol increased under all stress conditions examined, while an increase in intracellular glycerol was apparent only in salt-stressed cells. The significance of these findings in relation to stress tolerance in salt marsh environments is discussed.