HealthWise: New outbreaks need better disease surveillance
Zika outbreaks are particularly worrying in a country like India where 25.5 million births happen every year, zika outbreaks can cause hundreds of cases of foetal abnormalities.Updated: Dec 30, 2018 10:16 IST
Disease outbreaks in India occur with seasonal regularity, with each region having its own particular malaise. The monsoons, for example, bring dengue to Delhi, leptospirosis to Mumbai, chikungunya to Karnataka, encephalitis to eastern Uttar Pradesh and Bihar, and malaria to Chattisggarh, Jharkhand and Odisha.
In 2018, two new potentially fatal infections struck populations several hundred miles away from regions where these diseases had previously occurred, catching epidemiologists and public health experts off guard.
One was Nipah virus disease, which was reported for the first time l in Kerala, where it killed 17 persons in Kozhikode and Malappuram districts in Kerala in May and June. The infection, which was first reported in India in 2001 in Siliguri, West Bengal, when 66 cases and 45 deaths were confirmed, has since then been found in Pteropus giganteus bats or fruit bats.
Low levels of the virus stays in bats without sickening them. A few very ill bats secrete the virus in their droppings, saliva and other body fluids, exposure nasal or respiratory droplets, urine or blood, leading to infection in humans.
The virus jumped from bats to pigs to humans in Malaysia in 1998-99, and then from bats to humans in Bangladesh and India. The second outbreak in India was in Nadia district in West Bengal in 2007 which killed all the five persons infected.
Nipah virus spread to humans in India through the consumption of contaminated fruit or date palm sap or through direct contact with a sick bat’s body fluids or droppings. Human-to-human transmission was also documented in the Kerala outbreak, as it was in Siliguri in 2001.
Zika was contained by orientating hospitals and health workers on infection prevention and control practices, surveillance and contact tracing, implementing contagion treatment protocols, using personal protection equipment, and practicing safe burial practices.
Following the Nipah outbreak, Indian Council of Medical Research’s (ICMR) regional lab network for high-hazard pathogen testing were put on alert, which led to the next big outbreak to be identified through routine surveillance.
On September 22, the Jaipur lab of the ICMR’s zika surveillance system, involving 34 laboratories to detect Zika virus infection in patients with fever, identified the first of the 159 cases of India’s biggest outbreak to date. One case each was detected in Bhopal, Sehore and Vidisha districts in Madhya Pradesh on October 30.
By end of November 27, zika had sickened 289 people in Madhya Pradesh and Rajasthan. Zika was first reported in India reported in 2017, with three cases in Ahmedabad, Gujarat and one case in Krishnagiri District of Tamil Nadu.
Zika virus is known to be circulating in the south and south east asia region, according to the World Health Organisation, which did not change the global risk assessment after the India outbreak or recommend any travel or trade restriction to India.
Zika is a viral infection that causes mild fever and is spread by the aedes aegypti mosquito, which also spreads dengue and chikungunya. It was believed to be harmless until an outbreak in Brazil in 2015 linked the zika infection in pregnant women with newborn microcephaly, where babies are born with a smaller than normal head, and congenital defects.
“The environment in India is conducive for ZIKV (zika virus) because of preponderance of the Ae. aegypti mosquitoes. Though these mosquitoes breed throughout the year in and around the houses in potable water sources, the density is extremely high during monsoon since more number of breeding sites becomes available. High humidity and optimal temperature support their survival for many days,” states a 2017 paper published in the Indian Journal of Medical Research.
Zika outbreaks are particularly worrying in a country like India where 25.5 million births happen every year, zika outbreaks can cause hundreds of cases of foetal abnormalities. To prevent newborns being affected, all pregnant women were screened for fever and tested for zika.
To date, no cases of microcephaly or congenital zika syndrome have been reported, but with 80% people not developing symptoms, the risk to pregnant women and their unborn child remains high.
Both zika and nipah here to stay, India needs to expand its disease surveillance networks to identify and contain disease before they infect hundreds.