Researchers
in West Bengal have reported a second strain of the Japanese encephalitis virus
circulating in the eastern Indian state.
Researchers in West Bengal have reported a
second strain of the Japanese encephalitis virus (JEV) circulating in the
eastern Indian state.
According to a study published online in the
Virology Journal last month, the researchers confirmed genotype I (GI) of JEV
coexisting with the predominant genotype III (GIII) strain in over a quarter of
135 patients hospitalized for acute encephalitis syndrome.
The GI strain was first detected in India
three years ago in the Gorakhpur area of the northern state of Uttar Pradesh.
Led by Shyamalendu Chatterjee at the virus
unit of the Indian Council of Medical Research (ICMR) in Kolkata, the
researchers have now confirmed the GI strain in the samples of blood and fluid
from the brain and spinal column of patients admitted to government hospitals
in eight West Bengal districts between July and December 2010.
JE, which causes brain fever, is rampant in
West Bengal despite an active vaccination program.
The ICMR scientists, who were joined by
Subhra Kanti Mukhopadhyay from the microbiology department of the University of
Burdwan, were unable to ascertain how the GI strain, earlier reported
circulating in South Korea, Thailand, and China, had reached India.
But, the researchers said the possibilities
were that the GI strains were brought in by travelers, migratory birds (such as
herons), or mosquitoes blown in by cyclonic winds. Domestic pigs are known
reservoirs of JEV.
Transmitted to humans by the culex mosquito,
the symptoms of JE include severe rigors, convulsions, and high temperature.
Patients may go into coma and the fatality rate is high among child victims.
First isolated in Japan in 1935, JEV has
become a major public health menace with a worldwide case-fatality rate of 30
percent. 30 to 50 percent of survivors develop permanent brain damage.
The isolation of the GI strain in West Bengal
has cast doubts about the efficacy of vaccines currently used against JE
derived from the GIII strain.
“In future, JE outbreak is quite likely in
the state if this vaccine fails to protect sufficiently against GI of JEV,” the
researchers noted in their study.
Other experts said there was no cause for
panic.
“GIII-derived vaccine is used in countries
where the GI strain is prevalent and has been found to be effective. I do not
think there is any risk,” Komal Kushwaha, a physician at the Baba Raghav Das
Medical College in Gorakhpur, told SciDev.Net.
Kushwaha suggested carrying out a study by
completely immunizing one district and keeping another as control over a period
of two years.
The article can be found at: Sarkar A et al. (2012) Molecular evidence for
the occurrence of Japanese encephalitis virus genotype I and III infection
associated with acute Encephalitis in Patients of West Bengal, India, 2010.
Source: Science and Development
Network
No comments:
Post a Comment