Spatio-temporal epidemiology of Japanese encephalitis virus infection in pig populations of eastern Uttar Pradesh, India, 2013-2022.

AIMS: Japanese encephalitis (JE) is endemic in India. Although pigs are considered important hosts and sentinels for JE outbreaks in people, limited information is available on JE virus (JEV) surveillance in pigs. METHODS AND RESULTS: We investigated the spatio-temporal distribution of JEV seroprevalence and its association with climate variables in 4451 samples from pigs in 10 districts of eastern Uttar Pradesh, India, over 10 years from 2013 to 2022. The mean seroprevalence of IgG (2013-2022) and IgM (2017-2022) was 14% (95% CI 12.8-15.2) and 10.98% (95% CI 9.8-12.2), respectively. Throughout the region, higher seroprevalence from 2013 to 2017 was observed and was highly variable with no predictable spatio-temporal pattern between districts. Seroprevalence of up to 60.8% in Sant Kabir Nagar in 2016 and 69.5% in Gorakhpur district in 2017 for IgG and IgM was observed, respectively. IgG seroprevalence did not increase with age. Monthly time-series decomposition of IgG and IgM seroprevalence demonstrated annual cyclicity (3-4 peaks) with seasonality (higher, broader peaks in the summer and monsoon periods). However, most variance was due to the overall trend and the random components of the time series. Autoregressive time-series modelling of pigs sampled from Gorakhpur was insufficiently predictive for forecasting; however, an inverse association between humidity (but not rainfall or temperature) was observed. CONCLUSIONS: Detection patterns confirm seasonal epidemic periods within year-round endemicity in pigs in eastern Uttar Pradesh. Lack of increasing age-associated seroprevalence indicates that JEV might not be immunizing in pigs which needs further investigation because models that inform public health interventions for JEV could be inaccurate if assuming long-term immunity in pigs. Although pigs are considered sentinels for human outbreaks, sufficient timeliness using sero-surveillance in pigs to inform public health interventions to prevent JEV in people will require more nuanced modelling than seroprevalence and broad climate variables alone.

Prevalence and genotypic (G and P) determination of porcine group A rotaviruses from different regions of India.

Group A rotaviruses can infect both humans and animals and have been recognized as an important cause of diarrhea in porcine. In this study, we report the prevalence and molecular epidemiology of rotaviruses detected in piglets in different regions of India. A total 275 fecal samples (180 diarrheal and 95 non-diarrheal) from piglets were collected from the western (135), southern (60), northern (20), and North-Eastern Hill (NEH) (60) regions of India and tested for rotaviruses. All the samples were subjected to sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and reverse transcription-polymerase chain reaction (RT-PCR). Rotaviruses were detected in 10.18 % of samples by SDS-PAGE and/or RT-PCR with a maximum of 30 % from the NEH region followed by 7.4 % from the western region. Samples from the southern and northern regions were found to be negative. Only 10 isolates were subjected to genotypic characterization using amplification of VP7 and VP4 genes followed by two separate multiplex PCR assays for G genotyping and another two for P genotyping using genotype-specific primers. Of these, three isolates could be typed as G4 specificity, one with G9, and three as P[6] leading to identification of an uncommon strain, G4P[6]. One isolate was further confirmed by nucleotide sequencing. The data demonstrate genetic diversity of porcine rotavirus strains and suggest that pig farms may serve as potential reservoirs for human infections.

Use of a phospholipase-C assay, in vivo pathogenicity assays and PCR in assessing the virulence of Listeria spp.

Listeria spp. was isolated from 19.8% of animals with a history of reproductive disorders. A total of 333 faecal, genital swab and blood samples from 111 animals (cattle, buffaloes, sheep and goats) were subjected to PCR to detect virulence-associated genes (prfA, plcA, hlyA, actA and iap) and pathogenicity testing by the phosphatidylinositol phospholipase-C (PI-PLC) assay, and by mouse and chick embryo inoculation. One isolate of Listeria ivanovii recovered from a genital swab from a sheep was found to be pathogenic. Virulence assessment was then carried out on two L. ivanovii and 29 Listeria monocytogenes isolates from various sources using these assays. Haemolytic L. monocytogenes isolates lacking the plcA gene and PI-PLC activity were deemed non-pathogenic when assessed by mouse and chick embryo inoculation tests, in spite of having the hlyA gene. The results suggested that the PI-PLC and PCR assays are reliable in vitro alternatives to in vivo pathogenicity tests for L. monocytogenes.