Japanese encephalitis patient ‘isolated’ case, no fear of outbreak in Delhi

The recent diagnosis of Japanese encephalitis (JE) in a 72-year-old patient from Delhi is an “isolated case” and does not indicate an outbreak in the Capital, people familiar with the matter at the National Centre for Disease Control (NCDC) said on Thursday.
Japanese encephalitis, a zoonotic viral disease caused by the JE virus, is transmitted from animals – particularly pigs, and birds belonging to Ardeidae family such as cattle egrets, pond herons etc. – to humans by the Culex mosquito of the Vishnui group.
The 72-year-old patient in question, a resident of Uttam Nagar in West Delhi, was admitted to the All India Institute of Medical Sciences (AIIMS), Delhi, on November 3, with an acute onset of chest pain, the people cited above said.
A known diabetic for over two decades with coronary artery disease and congestive heart failure, the patient also suffered from bilateral lower limb weakness and bowel and bladder incontinence over the past five months.
“During the course of admission, the patient was tested for JE (blood sample collected on November 6, 2024) tested positive for JE IgM ELISA,” said the people cited above, requesting anonymity. Japanese Encephalitis (JE) IgM ELISA is a test to detect Immunoglobulin M antibodies to determine if they have been exposed to the JE virus.
The patient has since recovered and was discharged on November 15.
While Delhi has not reported JE outbreaks in the past, isolated cases have occasionally surfaced, primarily in patients referred from neighbouring states to tertiary hospitals such as AIIMS, Ram Manohar Lohia Hospital, and Safdarjung Hospital.
The last confirmed case in Delhi was reported in 2011.
Public health officials said that necessary measures are being implemented. “While all public health measures have been instituted as per National Centre for Vector Borne Disease Control (NCVBDC) guidelines, there is no cause for concern with respect to this isolated case of JE,” they added.
The public health department of Municipal Corporation of Delhi (MCD) is intensifying vector control measures in Uttam Nagar and surrounding areas as a preventive measure.
An order issued by the public health department on November 27, read, “The case fatality rate of the disease is high… keeping in view all deputy health officers and epidemiologists are directed to intensify vector control measures including larval source reduction and community-based initiatives for prevention and control of JE.”
Japanese encephalitis does not transmit between humans.
The infection generally presents with symptoms similar to any other viral encephalitis infection. Symptoms can include headache, fever, signs of meningitis, stupor, disorientation, coma, tremors, paralysis (generalised), hypertonia, loss of coordination, etc.
First human case of JE in India was reported in 1955 in Vellore, Tamil Nadu.
JE cases in India often follow a seasonal pattern, with increased transmission during the monsoon (July to August) and post-monsoon period (October to November) with an increase in season mosquito breeding. Outbreaks typically occur from July to October, peaking during the rainy season.