CHENNAI: It has spread panic across continents from Africa to America to Asia, including India, where experts say it is just a matter of time before the infections are detected. But Zika, the latest viral fever on the rounds, is not exactly new to the country.
A study done way back in 1952-53 found that one-sixth of the blood samples tested showed immunity to the virus - the clearest indication that the Zika had made its way to India and infected these persons, which helped their bodies develop antibodies to tackle it.
“Positive results obtained in the present study with Ntaya, Zika and Uganda S viruses are the first indications that these agents occur outside Africa,” said the study, ‘Neutralising antibodies against certain viruses in the sera of residents of India’, which was published in the prestigious Journal of Immunology in April 1954.
As part of their research, K C Smithburn, J A Kerr and P B Gatne collected samples from 588 people, a majority of them young men, from 38 localities spread across six states then — Bombay, Madras, Mysore, Hyderabad, Saurashtra and Madhya Pradesh. In Tamil Nadu (Madras), samples were collected from Tiruvallur and Kadambathur, which were part of the then composite district of Chingleput [Chengalpet]. The initial plan was to study the presence of antibodies that can neutralise the two arthropod-borne virus diseases that were considered as the most likely to be present in India - Japanese B and Russian spring summer encephalitis. This was to help orient the field work of the Virus Research Centre at Pune (now the National Institute of Virology, which was just established).
Subsequently, the scope of the study was expanded to include 13 more including Zika, yellow fever and West Nile viruses. During the research, the team found that 33 of the 196 samples had antibodies against Zika, including two that neutralised only this specific virus and none of the other 14. The researchers considered this as the “certain” evidence that people in India were infected by Zika.
Though those with immunity to Zika were found scattered across all regions, the report said high incidence of immunes was found in Broach district in Bombay (7 out of 17 samples), Sorath district in Saurashtra (4/11) and Nagpur district in Madhya Pradesh (7/15). Bareja in Ahmedabad district in Bombay showed highest incidence in a single locality (7/10). Out of 13 samples tested in Madras, one from Tiruvallur was found to have antibody.
Of the 33 samples that neutralised Zika, 28 were tested against all 15 viruses. As many as 26 of them had antibodies not just against Zika, but one or more other viruses as well. “Protection against Zika virus was not regularly associated with protection against any other agent, and it seems probable that the protective sera represents specific infections with Zika virus,” the report added. “The frequency with which an individual already immune to a specific virus is reexposed to the same agent may be found to influence the capacity of his serum to cross react with related viruses to which he has not been exposed. Until further information can be obtained on these points, obliged to be tentative in the interpretation of results, with full realisation that future discoveries may require revision of our views,” the report also observed.
Though the virus was detected decades ago, there have not been any further studies on this, as Zika was not considered as a public health problem till now.
Fever hitches a ride on dengue carrier Aegypti
IT is only a matter of time before the Zika virus is detected in India, as the country already has mosquitoes such as aedes aegypti, commonly associated with dengue, which spread fever, say experts.
The concern over this virus has heightened after scores of people in Singapore, many of them of Tamil origin, were tested positive for the virus, and also after the reputed medical journal, Lancet, published a study saying Indians were among the most vulnerable population to this virus.
“India does face the threat, as the mosquito that can spread this virus is already here. So, it is only a question of time before Zika enters the country,” the secretary of the Department of Health Research, Health Ministry, Dr Soumya Swaminathan, told Express. After making its presence felt as a viral fever that seemed to exist only in South American countries such as Brazil, Zika penetrated the Asian population with cases being reported in China and most recently in Singapore where 82 people, including 13 Tamils, have been detected positive as on August 30, 2016. So far, the WHO has put out a list of 60 countries that have recorded its presence, both widespread and sporadic.
The Health Ministry has issued guidelines to all states, advising them to be alert and also directing them to initiate intense surveillance at all airports across the country.
The symptoms are deceptively ordinary - joint pains, rash, red eyes, and mild fever that the person might not even pay attention to. With its clinical signs being similar to dengue, Zika infection may be misdiagnosed in areas where dengue is common. Hence, the authorities here are testing for Zika, especially in those cases where the person has been tested negative for dengue and chikungunya.
“Because this viral infection does not show many symptoms, detecting cases is a challenging task,” added Dr Soumya, also the Director General of the Indian Council of Medical Research (ICMR).
Though the fever can be managed with fluids, there is a panic over Zika because it poses a particular risk to pregnant women. The infection is believed to cause microcephaly, a severe birth defect among children, who are born with underdeveloped brains and abnormally small heads. There is no conclusive evidence for this yet, but the fear is real.
“Protecting pregnant women will be the real challenge,” said the Director of Public Health, Dr K Kolandaswamy.