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Research shows how mothers protect their babies from chickenpox

Image for representation purpose only.

Image for representation purpose only.  

‘Findings will revolutionise present day understanding of how babies are protected against infections in childhood’

Mothers with a past history of chickenpox infection may transmit chickenpox viral DNA to their babies during pregnancy, thereby stimulating their immunity against this infection, says a new study.

This mother-to-child transfer of viral DNA may be responsible for the long-lasting protection against serious chickenpox infection seen during childhood, according to its findings recently reported in the prestigious peer-reviewed journal, Viral Immunology.

“The findings will revolutionise the present day understanding of how babies are protected against infections like chickenpox in childhood,” said Jacob Puliyel who, along with his colleagues from St. Stephens Hospital, studied 350 mothers and their newborn babies for the study.

The study states that chickenpox reactivation after surgical stress is known. Scientists have also demonstrated that the stress of space travel can induce subclinical reactivation of chickenpox in astronauts. “Subclinical reactivation of chickenpox, induced by the stress of pregnancy, is being reported for the first time,” the authors say.

Long-lasting

The present understanding is that mothers provide their babies protection against a variety of common infections by transferring readymade antibodies to them. The protection to the baby lasts for 12 to 15 months. If the baby encounters the infection while it is partially protected by maternal antibodies, the illness is mild. The baby then develops their own, long-lasting immunity.

Dr. Puliyel and colleagues suggest that in the case of chickenpox, the mother’s viral DNA is transferred to their babies. It is likely that in such cases, antibodies are developed actively in the foetus.

“Babies develop more long-lasting active immunity with the transfer of chickenpox DNA from mothers — more than the short-term passive protection provided by the transfer of readymade antibodies,” the authors say.

More than vaccination

In the absence of vaccines, chickenpox spreads easily in the population and repeated exposure to the virus acts like booster doses. The high antibody levels — much higher than that after vaccination — are passed to babies and it protects them. Vaccination, on the other hand, will reduce person to person spread of natural disease and the antibody titres are not boosted, and so there is little protection provided to the next generation.

According to the authors, the “chickenpox parties” held in countries like the U.K. to get children exposed to others with chickenpox was not necessarily a bad idea, as they get naturally infected in childhood, when the disease is typically mild, and later in life, they are likely to pass on protecting chickenpox antibodies and DNA to their offspring.

The authors found antibody levels against chickenpox in newborn babies were often higher than that in mothers, suggesting that the antibody was actively transported to the baby.

Understanding broadened

“These findings broaden our understanding of how man has evolved to coexist, survive and even thrive with the micro-organisms in the environment,” the authors say, adding that government disease control plans with vaccines — for infections which are not considered lethal — have the potential to disturb this equilibrium. “This needs to be factored in when embarking on global disease eradication programmes,” they caution.

Chickenpox is primarily a disease of the temperate regions, where it occurs throughout the year, commonly in children between 1 and 14 years of age. The prevalence of the disease in these areas is 13-16/1,000 people per year.

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Printable version | Apr 6, 2020 2:27:47 AM | https://www.thehindu.com/news/national/research-shows-how-mothers-protect-their-babies-from-chickenpox/article30331264.ece

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