JAPANESE ENCEPHALITIS & OTHER- INDIA (15): (KERALA)
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A ProMED-mail post
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International Society for Infectious Diseases
http://www.isid.orgDate: Mon 26 Aug 2013
Source: The Hindu [edited]
http://www.thehindu.com/todays-paper/tp-national/je-west-nile-turning-killers/article5060340.eceA serious threat of Japanese encephalitis (JE) or West Nile (WN) virus outbreak looms large over Alappuzha district [Kerala state], which is prone to water stagnation and consequent mosquito menace post-monsoon.
The National Institute of Virology (NIV) Alappuzha unit reported to the district health administration in the beginning of July [2013] that the cerebrospinal fluid (CSF) samples from 28 patients with acute encephalitis syndrome (AES) -- all dead -- had tested positive for the JE-WN complex. But the State Health authorities had been unaware of this till the end of July 2013, when a Central team of public health officials, led by Kalpana Barua, visited the State. Public experts have sounded the alert already, as a significant number of AES cases reported in the district in May-July [2013] have tested positive for the JE-WN complex.
Strange enough, the district health administration had maintained that these 28 deaths could not be considered "cases" of JE-WN complex because the clinical symptoms of the patients did not meet the classic definition of AES.
According to them, the district had only about 30-plus cases of AES since May [2013], leading to 4 deaths, which had been reported to the State health administration.
Senior health officials have pointed out that regardless of whether the 28 persons died from JE-WN or not, the laboratory findings about the presence of the twin infections in so many persons have huge public health significance, which cannot be ignored.
"Alappuzha district has been endemic to JE, WN, dengue, and other mosquito-borne diseases for long. In the past 2-3 years, we have had many cases of encephalitis, most of which could be either JE or WN because it is difficult to distinguish using clinical symptoms or lab diagnosis. Both cause serious neurological diseases and leave the patients with severe 'sequelae,' including cognitive dysfunction, memory loss, or epileptic episodes. The seriousness of the situation cannot be diluted," B Padmakumar, Additional Professor of Medicine, Government Medical College, Alappuzha, says.
The JE and WN viruses belong to the same family of flaviviruses and are zoonotic infections maintained in a cycle involving migratory birds, mammals such as pigs and horses, and the _Culex_ species of mosquitoes, which breed in stagnant water. JE was first reported in Alappuzha in 1996, and till 1999, there have been major outbreaks.
Between 2005 and 2009, very few confirmed cases of JE were reported from Alappuzha, which the Health Department admits was probably because of the problems in properly diagnosing and confirming the disease. All cases involving high fever, convulsions, and altered sensorium were reported by the health system as AES.
"Both JE and WN are antigenically similar (viral antigen properties are similar) and complex genotyping is required to distinguish either. Immunoglobulin M (IgM) testing of CSF samples of an encephalitis patient gives only the confirmation as JE-WN or any other flavivirus. Virus neutralisation assay is required to differentiate between JE or WN, which could be time-consuming," says B Anukumar, scientist in-charge of the NIV wing at Alappuzha.
From the public health point of view, it is important that JE and WN surveillance is started in all districts and steps to contain it are intensified, Dr Anukumar says. JE mostly affects children less than 15 years, while WN usually affects older adults. In 2006, during the major chikungunya [virus] epidemic in Alappuzha, some scientists had raised the possibility of the co-circulation of WN virus because of the high rate of mortality during the epidemic.
However, NIV gave conclusive evidence about the major presence of WN virus in the region in 2011 during an AES outbreak when 208 cases were reported.
The district health administration has pointed out that the 28 patients who died from JE-WN, as reported by the NIV, were all elderly persons with various co-morbidities and that they did not have any AES symptoms. "Lab findings should have clinical correlation also. These persons are living in an endemic area where various flaviviruses are in circulation. It is possible that they were infected by JE-WN viruses, which came up in the lab diagnosis. It does not mean that those persons died of JE or WN," a senior official in Alappuzha says.
The NIV has clarified that all samples of the CSF that they had tested were of patients who had encephalitis meningitis symptoms. The samples were sent from the Alappuzha Medical College hospital.
"We just tested the CSF samples we received and reported our findings. It is possible that the patients presented a different spectrum of clinical symptoms, which did not fit into the classical definition of AES. The mean age of the patients was 60 years. We have not reported that the 28 deaths were due to JE/WN, but that these persons were exposed to the JE/WN viruses and that IgM positivity of the CSF indicates acute exposure. It is for the Health department to take suitable follow-up action," says Dr Anukumar.
[Byline: C Maya]
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ProMED-mail from HealthMap Alerts
[Both West Nile virus (WNV) and Japanese encephalitis virus (JEV) occur in southern India, and it is possible that these patients could have been infected with either one, although that diagnosis is disputed by the district public health administration. The diagnoses were made on the basis of serology, the interpretation of which is confounded by flavivirus cross reactivity, as mentioned in the report above.
No mention was made about attempts to detect virus sequences by PCR. Although virus neutralization tests may be too slow to provide a diagnosis for patients while they are hospitalized, it is critical to know which viruses are circulating in the area, and that requires neutralization testing.
There is a vaccine available for JEV but not for WNV. The report above makes no mention of the vaccination history of the patients, or of plans to vaccinate others in the areas where the patients acquired their infection should further testing indicate that JEV is circulating there.
