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Background: Earlier serosurveys in India revealed seroprevalence of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) of 0.73% in May–June 2020 and 7.1% in August–September 2020. A third serosurvey was conducted between December 2020 and January 2021 to estimate the seroprevalence of SARS-CoV-2 infection among the general population and healthcare workers (HCWs) in India. Methods: The third serosurvey was conducted in the same 70 districts as the first and second serosurveys. For each district, at least 400 individuals aged ≥10 years from the general population and 100 HCWs from subdistrict-level health facilities were enrolled. Serum samples from the general population were tested for the presence of immunoglobulin G (IgG) antibodies against the nucleocapsid (N) and spike (S1-RBD) proteins of SARS-CoV-2, whereas serum samples from HCWs were tested for anti-S1-RBD. Weighted seroprevalence adjusted for assay characteristics was estimated. Results: Of the 28,598 serum samples from the general population, 4585 (16%) had IgG antibodies against the N protein, 6647 (23.2%) had IgG antibodies against the S1-RBD protein, and 7436 (26%) had IgG antibodies against either the N protein or the S1-RBD protein. Weighted and assay-characteristic-adjusted seroprevalence against either of the antibodies was 24.1% [95% confidence interval (CI) 23.0–25.3%]. Among 7385 HCWs, the seroprevalence of anti-S1-RBD IgG antibodies was 25.6% (95% CI 23.5–27.8%). Conclusions: Nearly one in four individuals aged ≥10 years from the general population as well as HCWs in India had been exposed to SARS-CoV-2 by December 2020.

Background: Early and accurate diagnosis of malaria is critical to the success of malaria elimination. However, the current mainstay of malaria diagnosis in the field, such as light microscopy and rapid diagnostic tests (RDTs), have limitations due to low parasite density or mutation in diagnostic markers. Methods: We evaluated an inexpensive, robust, rapid, malaria diagnostic device, called Gazelle, that employs magneto-optical detection to identify haemozoin crystals (Hz) produced by all species of human malaria parasites in infected individuals. A beam of polarised light is passed through the lysed diluted blood sample under the influence of high (~.55T) and low magnetic fields. The difference in light transmission through the sample between the high and low magnetic fields indicates presence of Hz, suggesting possible malarial infection. A total of 300 febrile patients were screened at the malaria clinic of Indian Council of Medical Research-National Institute of Research in Tribal Health (ICMR-NIRTH), Jabalpur, India, from August 2018 to November 2018. Malaria diagnosis was done using four diagnostic methods: Gazelle, light microscopy, RDT, and malaria specific Polymerase Chain Reaction (PCR). Measures of diagnostic accuracy were compared. Findings: Out of 300 febrile patients enroled and tested for the presence of malaria parasites, 262 patient samples were included in the final analysis. The sensitivity and specificity of Gazelle was 98% and 97% in comparison to light microscopy, 82% and 99% to PCR and 78% and 99% to RDT, respectively. The results of the four diagnostic methods were comparable and statistically no significant differences in sensitivity or specificity was observed between these methods. Enhanced diagnostic accuracy of Gazelle in malaria patients with no prior history of malaria treatment was observed in this study. Interpretation: The diagnostic ability of Gazelle was comparable to light microscopy and better than RDTs even in low parasitemia and in presence of pfhrp2/3 deletion mutant parasites. Gazelle may be a novel valuable diagnostic tool in resource poor settings where (i) microscopy is not feasible and (ii) pfhrp2/3gene deleted parasite are present. Its speed, cost-efficiency, and alternative to lack of microscopists makes it an important adjunct in field settings. Funding: HemexDx, India.

TNF-α is an important human cytokine that imparts dualism in malaria pathogenicity. At high dosages, TNF-α is believed to provoke pathogenicity in cerebral malaria; while at lower dosages TNF-α is protective against severe human malaria. In order to understand the human TNF-α gene and to ascertain evolutionary aspects of its dualistic nature for malaria pathogenicity, we characterized this gene in detail in six different mammalian taxa. The avian taxon, Gallus gallus was included in our study, as TNF-α is not present in birds; therefore, a tandemly placed duplicate of TNF-α (LT-α or TNF-β) was included. A comparative study was made of nucleotide length variations, intron and exon sizes and number variations, differential compositions of coding to non-coding bases, etc., to look for similarities/dissimilarities in the TNF-α gene across all seven taxa. A phylogenetic analysis revealed the pattern found in other genes, as humans, chimpanzees and rhesus monkeys were placed in a single clade, and rats and mice in another; the chicken was in a clearly separate branch. We further focused on these three taxa and aligned the amino acid sequences; there were small differences between humans and chimpanzees; both were more different from the rhesus monkey. Further, comparison of coding and non-coding nucleotide length variations and coding to non-coding nucleotide ratio between TNF-α and TNF-β among these three mammalian taxa provided a first-hand indication of the role of the TNF-α gene, but not of TNF-β in the dualistic nature of TNF-α in malaria pathogenicity.