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West Nile encephalitis outbreak in Kerala, India, 2011.
J Clin Virol. 2014 Sep; 61(1):152-5.JC

Abstract

BACKGROUND

An outbreak of acute encephalitis syndrome (AES) was reported in Kerala in India in May 2011. The outbreak features were unusual in terms of seasonality, geographical distribution, age group, and clinical manifestations in comparison to the epidemiological features of Japanese Encephalitis.

OBJECTIVE

To detect the etiology of the acute encephalitis syndrome outbreak.

STUDY DESIGN

Investigation of outbreak was undertaken by collection of brief clinical history and epidemiological details along with the specimens for viral diagnosis. The serum/CSF samples (patients=208) received from the sentinel hospitals were subjected to IgM capture ELISA and RT-PCR specific for Japanese encephalitis (JE) virus and West Nile virus (WNV). The JE/WN IgM positive samples were further tested by serum neutralization assay for the presence of JE and WNV specific neutralizing antibody.

RESULT

Most of the affected patients were aged above 15 years. No spatial clustering of the disease was noticed. Cases were observed in premonsoon and early monsoon season and in JE non-endemic area of Kerala. A total of 47 patient samples were positive for in-house JE IgM capture ELISA and WNV IgM capture ELISA. Serum neutralization assay result revealed that 32 of 42 (76.19%) sera were positive for WNV neutralization antibodies. WNV was isolated from a clinical specimen. Phylogenetic analysis of WNV envelope gene revealed 99% homology with Russian Lineage 1 WNV.

CONCLUSION

West Nile virus (WNV) etiology was confirmed by virus isolation and detection of virus specific antibody from clinical specimen. Phylogenetic analysis grouped the current strain in lineage I West Nile virus.

Authors+Show Affiliations

National Institute of Virology, Kerala, Govt. T. D. Medical College Hospital, Alappuzha 688005, Kerala, India. Electronic address: anukumar74@gmail.com.National Institute of Virology, 20-A, Dr. Ambedkar Road, Post Box No. 11, Pune 411001, Maharashtra, India. Electronic address: gajanansapkalniv@gmail.com.National Institute of Virology, 20-A, Dr. Ambedkar Road, Post Box No. 11, Pune 411001, Maharashtra, India. Electronic address: drtandale@gmail.com.National Institute of Virology, Kerala, Govt. T. D. Medical College Hospital, Alappuzha 688005, Kerala, India. Electronic address: balasniv@gmail.com.National Institute of Virology, 20-A, Dr. Ambedkar Road, Post Box No. 11, Pune 411001, Maharashtra, India. Electronic address: dayapavitrakar@gmail.com.

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

24985196

Citation

Anukumar, B, et al. "West Nile Encephalitis Outbreak in Kerala, India, 2011." Journal of Clinical Virology : the Official Publication of the Pan American Society for Clinical Virology, vol. 61, no. 1, 2014, pp. 152-5.
Anukumar B, Sapkal GN, Tandale BV, et al. West Nile encephalitis outbreak in Kerala, India, 2011. J Clin Virol. 2014;61(1):152-5.
Anukumar, B., Sapkal, G. N., Tandale, B. V., Balasubramanian, R., & Gangale, D. (2014). West Nile encephalitis outbreak in Kerala, India, 2011. Journal of Clinical Virology : the Official Publication of the Pan American Society for Clinical Virology, 61(1), 152-5. https://doi.org/10.1016/j.jcv.2014.06.003
Anukumar B, et al. West Nile Encephalitis Outbreak in Kerala, India, 2011. J Clin Virol. 2014;61(1):152-5. PubMed PMID: 24985196.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - West Nile encephalitis outbreak in Kerala, India, 2011. AU - Anukumar,B, AU - Sapkal,Gajanan N, AU - Tandale,Babasheb V, AU - Balasubramanian,R, AU - Gangale,Daya, Y1 - 2014/06/07/ PY - 2014/04/11/received PY - 2014/05/29/revised PY - 2014/06/02/accepted PY - 2014/7/3/entrez PY - 2014/7/6/pubmed PY - 2015/3/31/medline KW - Acute encephalitis syndrome KW - Disease outbreak KW - Flavivirus KW - India KW - Kerala KW - Lineage I West Nile virus SP - 152 EP - 5 JF - Journal of clinical virology : the official publication of the Pan American Society for Clinical Virology JO - J Clin Virol VL - 61 IS - 1 N2 - BACKGROUND: An outbreak of acute encephalitis syndrome (AES) was reported in Kerala in India in May 2011. The outbreak features were unusual in terms of seasonality, geographical distribution, age group, and clinical manifestations in comparison to the epidemiological features of Japanese Encephalitis. OBJECTIVE: To detect the etiology of the acute encephalitis syndrome outbreak. STUDY DESIGN: Investigation of outbreak was undertaken by collection of brief clinical history and epidemiological details along with the specimens for viral diagnosis. The serum/CSF samples (patients=208) received from the sentinel hospitals were subjected to IgM capture ELISA and RT-PCR specific for Japanese encephalitis (JE) virus and West Nile virus (WNV). The JE/WN IgM positive samples were further tested by serum neutralization assay for the presence of JE and WNV specific neutralizing antibody. RESULT: Most of the affected patients were aged above 15 years. No spatial clustering of the disease was noticed. Cases were observed in premonsoon and early monsoon season and in JE non-endemic area of Kerala. A total of 47 patient samples were positive for in-house JE IgM capture ELISA and WNV IgM capture ELISA. Serum neutralization assay result revealed that 32 of 42 (76.19%) sera were positive for WNV neutralization antibodies. WNV was isolated from a clinical specimen. Phylogenetic analysis of WNV envelope gene revealed 99% homology with Russian Lineage 1 WNV. CONCLUSION: West Nile virus (WNV) etiology was confirmed by virus isolation and detection of virus specific antibody from clinical specimen. Phylogenetic analysis grouped the current strain in lineage I West Nile virus. SN - 1873-5967 UR - https://www.unboundmedicine.com/medline/citation/24985196/West_Nile_encephalitis_outbreak_in_Kerala_India_2011_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S1386-6532(14)00217-0 DB - PRIME DP - Unbound Medicine ER -