Suspected cases of Japanese encephalitis, one of the most fatal of all mosquito–borne diseases, are on the rise in the city, with at least six reported last year alone. While there is a major outbreak in Uttar Pradesh and Andhra Pradesh, Mumbai too has seen a rise in incidence. In fact in the last three years, general encephalitis deaths – including other forms of the disease –have been on the rise in the city.

Data compiled by NGO Praja Foundation from death certificates of all ward offices shows that suspected encephalitis deaths in the city increased from 47 in 2008, 110 in 2009 and 142 in 2010, till when data was collected. The registered deaths, from both public and private hospitals, were due to many types of encephalitis. Though encephalitis, myelitis and encephalomyelitis together caused most deaths in the three–year period, while Japanese encephalitis saw seven deaths, the latter figure is alarming as it is the most fatal form. Viral encephalitis, another variant, recorded 88 deaths. The most vulnerable age groups were between 5 and 14, which recorded a total of 55 deaths in the period.

Encephalitis is a swelling of the brain that is most often caused by viruses, but can also be caused by bacteria, fungi or parasites.

Nitai Mehta, founder of Praja said the increase in deaths over the years is shocking. “The incidence of deaths has risen by 200% over three years. This does not reflect well on a city like Mumbai. Japanese encephalitis is caused by mosquitoes and there should be better surveillance and control of mosquito breeding,” he said.

Medical experts, however, say the data does not necessarily prove the disease has spread to Mumbaikars, adding the victims could have been visitors or migrants. Dr Daksha Shah, head of epidemiology cell, BMC, said there was no rise in confirmed cases. “Encephalitis has many varieties. It is not even established whether these were residents of Mumbai. It is highly possible that they came to the city with the virus and developed symptoms later, or came here for treatment and then died,” said Shah. “Often, when a patient dies, the doctor gives ‘suspected encephalitis’ as a preliminary observation. But this is not necessarily confirmed by another institution,” Shah said.

Dr Abhay Chowdhary, director of the Haffkine Institute said, “It is considered as a probable diagnosis if not confirmed by a lab. Besides, Japanese encephalitis is not major in Maharashtra. The increase could also mean there is better detection now due to which more cases are being reported.”