Babies born to women who have a history of chickenpox infection would possibly be immune to the infection, new research has shown. The babies would get the Chickenpox viral DNA from the mothers during pregnancy, the study says.
This mother-to-child transfer of viral DNA may be responsible for long-lasting protection against serious chickenpox infection seen during childhood, according to the study published in the journal, Viral Immunology.
The novel findings are an outcome of research on 350 mothers and their new born children by Dr Jacob Puliyel and his colleagues at the Delhi’s St Stephens Hospital. The results will revolutionize the present day understanding of how babies are protected against infections like chickenpox in childhood, authors of the study claim.
The authors found antibody levels against chickenpox in new-born babies were often higher than that in mothers suggesting that the antibody was actively transported to the baby.
It is well known that mothers provide their babies protection against a variety of common infections, by transferring ready-made 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.
Puliyel and colleagues suggest that in the case of chickenpox, mothers develop subclinical viremia and the viral DNA is transferred to their babies. It is likely that in such cases, antibodies are developed actively in the foetus.
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. "However, sub-clinical areactivation of chickenpox, induced by the stress of pregnancy, is being reported for the first time," the authors say.
"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.
In the absence of vaccines, chicken pox 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, the authors explain.
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, they say.
The authors also suggest that the ‘Chickenpox parties’ held in countries like the UK to get the 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. Later in life, they are likely to pass on protective antibodies and DNA to their offspring.
"These findings broaden our understanding of how man has evolved to coexist, survive and even thrive, with the microorganisms present in the environment," the authors say. Government disease control plans with vaccines -- for infections which are not considered lethal -- have a potential to disturb this equilibrium. "This needs to be factored-in when embarking on global disease eradication programmes," they caution.
