AsianScientist (Mar. 30, 2023) — An Adenovirus outbreak in India’s eastern state of West Bengal infected more than 12,000 children between January and March this year. This outbreak was unprecedented in scale and severity.
Adenovirus infection cases were also reported in other cities such as Mumbai, Pune, Bangalore, and Jaipur, but the situation in West Bengal was dire. According to the government statistics, the death toll is 19. However, paediatricians say that more than 150 children have died due to Adenovirus infections and related complications.
National Institute of Cholera and Enteric Diseases (NICED) in Kolkata analyzed genetic makeup of the Adenovirus samples collected from the affected children to ascertain the serotype of the virus. The serotype tells us how viruses are grouped based on the type of surface antigen present. The surface antigens enable bacterial attachment and invasion of host cells and the evasion of host immune defense mechanisms. The serotype analysis showed that the serotypes 3 and 7 and the recombinant strain 7/3 (the strain made by combining genetic material from type 3 and type 7), were found in most cases in West Bengal.
Paediatrician Apurba Ghosh said that Adenovirus epidemic has happened in West Bengal before but this year it is severe and the magnitude of the epidemic is unprecedented. He added that children up to two years of age are particularly vulnerable as their lungs are not fully developed.
This infection is limited to the upper respiratory tract in older children and young adults. But it can spread further to the lower airways in children between three months and two years of age, causing adenoviral pneumonia.
Prabhas Prasun Giri, associate professor of paediatrics and in-charge of PICU, Institute of Child Health, Kolkata, said that adenoviral pneumonia severely affects the lungs and compromises immunity, which increases the chances of secondary bacterial infections and bacterial sepsis.
Doctors interviewed for this story said that babies born during the pandemic are habituated to living in a sanitized environment and have not acquired immunity to common infections. This “immunity gap” has also contributed to the severity of the infections.
Though the virus had mostly affected children below the age of two years, a teenager lost her life to an Adenovirus infection. Subhrojyoti Bhowmick, clinical director at Peerless Hospital & B K Roy Research Center, where the girl was admitted, explained that the teen had spinal muscular atrophy, a medical condition which weakens the respiratory muscles. Then the adenovirus “infection further weakened her respiratory muscles, preventing them from performing routine functions,” he said.
In Asia, large-scale adenovirus outbreaks have also occurred in China, Taiwan, Singapore, and Malaysia. Moreover, adenovirus is thought to be the reason behind the worldwide viral hepatitis outbreak last year because adenovirus remains the most frequently detected pathogen in the tested hepatitis cases, according to the World Health Organization (WHO).
WHO added that assessing whether the rate of hepatitis cases with adenovirus infections are higher than expected in the population is challenging due to limited adenovirus surveillance in most countries.
Between November 2012 and July 2013, Singapore witnessed a marked increase in Adenovirus type 7 (Ad7) infections among children. In November 2012, KK Women’s and Children’s Hospital in Singapore reported the first confirmed case of adenovirus type 7. The number of paediatric inpatients increased from 32 between January and July 2012 period to 200 between January and July 2013.
Many studies have been conducted, primarily in Singapore, to understand this sudden and severe outbreak. In the first large-scale study of adenovirus strains, researchers led by Duke-NUS Medical School studied more than 500 clinical samples, mostly from paediatric patients. They found increase in the types 4 and 7 in comparison to other strains in the pediatric population.
Based on the study results, the authors suggested that Singaporean public health officials and clinicians consider antiviral therapies and adenovirus vaccines. They also recommended systematic studies of clinical HAdV genotypes to identify patients at risk of severe disease.
Giri said that the development of the adenovirus vaccine must be seriously considered. He pointed out that many repeat hospitalizations of children infected with Ad7 happen due to recurrent infections and post-infectious bronchiolitis obliterans (PIBO), a severe, long-term respiratory condition, which has a poor prognosis and it adversely affects children’s quality of life. However, studies on risk factors for PIBO are limited.
Image: Shelly Liew/ Asian Scientist Magazine
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