Evaluating the efficiency of specimen pooling for PCR-based detection of COVID-19

In the age of a pandemic, such as the ongoing one caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the world faces a limited supply of tests, personal protective equipment, and factories and supply chains are struggling to meet the growing demands. This study aimed to evaluate the efficacy of specimen pooling for testing of SARS-CoV-2 virus, to determine whether costs and resource savings could be achieved without impacting the sensitivity of the testing. Ten previously tested nasopharyngeal and throat swab specimens by real-time polymerase chain reaction (PCR), were pooled for testing, containing either one or two known positive specimens of varying viral concentrations. Specimen pooling did not affect the sensitivity of detecting SARS-CoV-2 when the PCR cycle threshold (Ct) of original specimen was lower than 35. In specimens with low viral load (Ct > 35), 2 of 15 pools (13.3%) were false negative. Pooling specimens to test for Coronavirus Disease 2019 infection in low prevalence (≤1%) areas or in low risk populations can dramatically decrease the resource burden on laboratory operations by up to 80%. This paves the way for large-scale population screening, allowing for assured policy decisions by governmental bodies to ease lockdown restrictions in areas with a low incidence of infection, or with lower-risk populations.     

Anti-interferon-γ autoantibody and opportunistic infections: case series and review of the literature

Immune defects in interleukin-12-dependent interferon-gamma (IFN-γ) pathways are associated with disseminated infections caused by non-tuberculous mycobacteria (NTM) and Salmonella. Recently, there have been an increasing number of reports of acquired autoantibodies to IFN-γ in adults, especially in Asian patients. We describe here three human immunodeficiency virus-negative Thai adults who had persistent or recurrent disseminated infections caused by NTM, Salmonella, and other opportunistic pathogens, possibly due to anti-IFN-γ autoantibodies. The antibodies were shown to exhibit very high inhibitory activity to IFN-γ. Two patients also developed Sweet’s syndrome during the course of infections. In addition, we also review all previous reports of patients with anti-IFN-γ antibodies who were susceptible to NTM and Salmonella infections.     

Case Report: Autochthonous Visceral Leishmaniasis in a Human Immunodeficiency Virus (HIV)-Infected Patient: The First in Thailand and Review of the Literature

We report a case of visceral leishmaniasis in a human immunodeficiency virus (HIV)-infected 37-year-old Thai fisherman who presented with nephritonephrotic syndrome, fever, anemia, and thrombocytopenia. Bone marrow biopsy revealed many amastigotes within macrophages. Kidney biopsy showed membranoproliferative glomerulonephritis. Polymerase chain reaction (PCR) and nucleotide sequence analysis of the internal transcribed spacer 1 of the small subunit ribosomal RNA gene in blood and kidney biopsy specimens showed Leishmania species previously described in a Thai patient with visceral leishmaniasis. Only four autochthonous cases of leishmaniasis have been reported in Thailand since 1996. To the best of our knowledge, this is the first report of autochthonous visceral leishmaniasis in an HIV-infected Thai. With an increasing number of patients with autochthonous leishmaniasis in association with the presence of potential vector, it remains to be determined whether this vector-borne disease will become an emerging infectious disease in Thailand.Leishmaniasis is a vector-borne infection caused by an obligate intracellular protozoon, Leishmania sp., which is transmitted by phlebotomine sandflies.^1–3 It occurs worldwide in tropical and subtropical regions including the Middle East, India, China, Africa, and southern and central America. Thailand is not a known endemic area for leishmaniasis. Most imported cases were reported between 1960 and 1986 in Thai workers returning from the Middle East.^4,5 The first reported indigenous patient with leishmaniasis was a 3-year-old girl living at Suratthani Province of southern Thailand in 1996.⁶ Several autochthonous cases with leishmaniasis were recently seen in northern, central, and southern Thailand.^7–9 Interestingly, these patients were from provinces where a potential sandfly vector has never been reported.^10–12 We describe the first report of visceral leishmaniasis in a human immunodeficiency virus (HIV)-infected patient and review all previous reports of autochthonous cases of leishmaniasis in Thailand.