Tracking and predicting the African COVID-19 pandemic (preprint)

The ongoing coronavirus disease 2019 (COVID-19) pandemic is heterogeneous throughout Africa and threatening millions of lives. Surveillance and short-term modeling forecasts are critical to provide timely information for decisions on control strategies. We use a model that explains the evolution of the COVID-19 pandemic over time in the entire African continent, parameterized by socioeconomic and geoeconomic variations and the lagged effects of social policy and meteorological history. We observed the effect of the human development index, containment policies, testing capacity, specific humidity, temperature and landlocked status of countries on the local within-country and external between-country transmission. One week forecasts of case numbers from the model were driven by the quality of the reported data. Seeking equitable behavioral and social interventions, balanced with coordinated country-specific strategies in infection suppression, should be a continental priority to control the COVID-19 pandemic in Africa.

Detection of asymptomatic Leishmania infection in Bangladesh by novel antigen and antibody diagnostic tools shows strong association with PKDL patients (preprint)

BackgroundAsymptomatic Leishmania infections outnumber clinical infections on the Indian sub-continent (ISC) where disease reservoirs are anthroponotic. Diagnostics which detect active asymptomatic infection, which are suitable for monitoring and surveillance, may be of benefit to the visceral leishmaniasis (VL) elimination campaign on the ISC. Methodology/Principal FindingsQuantitative polymerase chain reaction (qPCR), loop mediated isothermal amplification (LAMP), the direct agglutination test (DAT), and the Leishmania antigen ELISA were carried out on blood and urine samples collected from 720 household and neighbouring contacts of 276 VL and post kala-azar dermal leishmaniasis (PKDL) index cases, with no symptoms or history of VL and PKDL, in endemic regions of Bangladesh between September 2016 and March 2018. Of the 720 contacts of index cases, asymptomatic infection was detected in 69 (9.6%) participants by a combination of qPCR (1.0%), LAMP (2.1%), DAT (3.9%), and Leishmania antigen ELISA (3.3%). Only 1 (0.1%) participant was detected positive by all 4 diagnostic tests. Poor agreement between tests was calculated using Cohens kappa (k) statistics, however the Leishmania antigen ELISA and DAT in combination capture all participants positive by more than one test. We find strong evidence for association between the index case being a PKDL case (OR 1.94, p = 0.009), specifically macular PKDL (OR 2.12, p = 0.004) and being positive for at least one of the four tests. Conclusions/SignificanceLeishmania antigen ELISA detects active asymptomatic infection, requires a non-invasive sample, and therefore may be of benefit for monitoring transmission and surveillance in an elimination setting in combination with serology. Development of an antigen detection test in RDT format would be of benefit to the elimination campaign. Author summaryInfection with the parasite Leishmania donovani can lead to an asymptomatic infection with only around 5% of asymptomatics converting to visceral leishmaniasis the clinical manifestation of the infection. Serological assays detect anti-Leishmania antibodies and therefore cannot distinguish between past and active infection. Molecular assays and those which detect Leishmania antigens detect active infection. Since the signing of a memorandum of understanding in 2005, visceral leishmaniasis has been targeted for elimination in India, Nepal and Bangladesh. In an elimination setting such as Bangladesh, where disease reservoirs are anthroponotic, a relatively simple test such as the Leishmania antigen ELISA which requires a non-invasive urine sample, may be of benefit in combination with serology for surveillance and monitoring of Leishmania transmission. Development of an antigen test into a field compatible rapid diagnostic test would be of further benefit to the elimination campaign.