Seasonal distribution and upsurge of respiratory viruses among indigenous tribes with ILI and SARI in a far-flung Car Nicobar Island

Abstract

Background: Respiratory viral illnesses among children are a prominent cause of morbidity and mortality in the developing world. The aim of this study is to understand the seasonal pattern and surge of respiratory viruses among the Nicobarese tribe.

Methods: Respiratory specimens were collected from both ARI and SARI cases attended the BJR district hospital in Car Nicobar Island, India, between 2021 and 2022. Respiratory viruses were identified from the specimens by using the qRT-PCR assay. Meteorological parameters were collected and evaluated using Microsoft Excel and SPSS 21. The significant association between the surge of respiratory viruses and each climatic parameter was evaluated.

Results: In this hospital-based cross-sectional study, 471 ILI cases were enrolled, and 209 of these were positive for respiratory viral infections. Of these respiratory virus infections, 201 (96.2%) were infected with a single respiratory virus infection, and 8 (3.8%) had mixed viral infections. Fever, cough, and chills were the most common symptoms of respiratory illness among this indigenous population. There was a significant link between respiratory viruses and influenza-like illness in children (below 5 years and 6 to 15 years).

Conclusion: This prevalence study revealed that viral respiratory infections were more common in children than adults. Among these respiratory viruses, respiratory syncytial virus A (RSV) and influenza B virus were predominantly reported among tribal children up to age five years. In the year 2021, these viruses were recorded frequently during the winter season. Climate factors such as high humidity, high precipitation, moderate temperature, and moderate rainfall are found to be correlated with respiratory viral infections. This study implicates important information for preventing a further outbreak of respiratory viral infections in Car Nicobar Island.

Keywords: ILI; Influenza; Island; Nicobarese; RSV; Respiratory virus.

Fig. 1

Symptomatic distribution of ILI in Car-Nicobar (A shows the symptomatic distribution of total ILI cases attended the hospital (N = 5840) & B depicts the symptomatic distribution of enrolled ILI cases in this study (N = 471)

Fig. 2

Positive rates of single viral respiratory infection and viral-viral co-infection with different age groups (Blue cone indicates the single viral respiratory infection and orange cylinder represents the viral-viral co-infections.)

Fig. 3

Distribution of respiratory viruses in Car Nicobar Island (Grey section represent the distribution of Rhinovirus, Adenovirus, PIV-1, PIV-3, PIV-4, HCoV-HKU1, HCoV-NL63.)

Fig. 4

Respiratory viruses among different age groups

Fig. 5

A Month wise distribution of RSV-A and B. Depicts the month wise distribution of the respiratory viruses

Fig. 6

Correlation between the upsurge of respiratory viral infection and Climatic conditions [(A) temperature, (B) relative humidity, (C) rainfall, and (D) precipitation]