The document summarizes information about a case of West Nile virus in India. It provides background on the virus, including that it was first identified in Uganda in 1937 and has since caused outbreaks globally. It then discusses the case of a 7-year-old boy in India who tested positive for the virus and later died. The health ministry responded by sending a team to investigate. It concludes by covering symptoms, transmission, detection methods and treatment of West Nile virus.

1. Dr. Shivaji Dev Barman
Senior Resident, Department of Community Medicine
Lady Hardinge Medical College, New Delhi
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2.  On 18th March, 2019 a 7 year old boy from Kerala who had tested
positive for West Nile virus and was under treatment, died in
Kozhikode.
 The Health Ministry had dispatched a four-member multi-
disciplinary team from National Centre for Disease Control (NCDC)
after the boy tested positive.
 The Indian Council of Medical Research (ICMR) was alerted and a
close watch is being maintained at central and state levels.
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3.  During 1999 and 2000, epidemics of severe neurological illness were
reported in New York (USA) among humans, horses and birds with
unprecedented morbidity and mortality.
 The causative organism was identified as West Nile (WN) virus.
 By the end of 2000, virus activity had spread to 12 states of the US.
 The WN virus responsible for the US outbreak was found to be
genetically related to a virus circulating in Israel from 1997 to 2000.
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4.  First isolated from the blood of an elderly woman with febrile illness
in West Nile district in Uganda (currently Nile Province) in 1937.
 The virus caused severe outbreaks in the Middle East, European
and African countries during 1950s and 70s.
 The increase in frequency and severity of outbreaks in humans and
animals since mid 1990s in these countries and its incursion for the
first time in USA, has caused much alarm as a Re-emerging disease.
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5.  The West Nile, Japanese Encephalitis
and Dengue viruses belong to
the family Flaviviridae.
• The virus contains single-stranded, positive-sense RNA containing
nucleotides enclosed in capsid protein and membrane glycoproteins
E and M, and non-structural proteins, NS.
 E protein is the most important structural protein eliciting
immunological responses.
 Phylogenetic analysis shows the WN virus isolated from different
geographical regions fall into lineage 1 or 2.
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7.  Birds act both as carriers and amplifying hosts of WN virus.
 Mosquitoes belonging mainly to Culex species act as vectors for
transmission of infection from viraemic birds to a large spectrum of
vertebrate hosts.
 No evidence of person to person/animal or animal to animal/person
transmission.
 The virus multiplies in the vector and after an extrinsic incubation
period of 2 weeks, the vector becomes infective for active
transmission to a susceptible host.
 Migratory birds play a major role in the virus transmission. 7

8. Since the original isolation of WN virus in 1937, notable outbreaks
were recorded in Israel (1951-54), South Africa (1974), Romania and
Morocco (1996), Tunisia (1997), Italy (1998), Russia, USA and Israel
(1999) and Israel, France and USA (2000).
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 Incubation period of 1 to 6 days.

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11.  Serological surveys during JE epidemics and in areas endemic to JE
show that the virus is highly prevalent in India.
 The virus has been isolated from human beings, frugivorous bats,
domestic pigs and mosquitoes.
 The virus is transmitted mostly by Culex vishnui in India and
genetically belongs to lineage 1.
 Neutralizing antibodies were detected in ardeid birds mainly from
pond herons and cattle egrets.
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12.  WNV neutralizing antibodies have been detected in human sera
collected from Tamil Nadu, Karnataka, Andhra Pradesh, Maharashtra,
Gujarat, Madhya Pradesh, Orissa and Rajasthan.
 Serologically confirmed cases were reported from Vellore and Kolar
districts during 1977, 1978 and 1981.
• Though the virus usually causes a
mild, non-fatal dengue like illness in
humans, febrile illness in epidemic
form and clinically overt
encephalitis cases were observed in
Udaipur area of Rajasthan,
Buldhana, Marathwada and
Khandesh districts of Maharashtra.
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13.  WNV infection is diagnosed by serological methods.
 Demonstration of four-fold rise or drop of antibody titer in paired
serum samples by Haemagglutination inhibition test is widely used.
 IgM–antibody capture ELISA is routinely used for diagnosis of acute
infection in human.
 An Arboviral immunofluorescence assay has been used for screening
of WNV infection in humans.
 Recently, the RT-PCR method for detection of virus-specific genome
has been extensively used.
 Virus isolation by cell culture.
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14.  No specific treatment, only symptomatic management of cases.
 Supportive therapy is recommended in encephalitis cases.
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15.  Strategies recommended for control of Culex
mosquitoes are applicable.
 The integrated vector control strategies include-
1. Use of personal protection measures (protective clothing, bed nets,
mosquito repellants)
2. Insecticides
3. Insecticide impregnated curtains and nets
4. Biological control methods by larvivorous fish, introducing natural
parasites and predators.
 Though a few candidate vaccines are under laboratory trial, no
vaccine is available commercially for the control of WNV infection in
human and animals.
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16.  World Health Organisation website: West Nile virus
 West Nile Fever data, 2012. In: Historical data [website]. Stockholm:
European Centre for Disease Prevention and Control; 2102
(http://ecdc.europa.eu/en/healthtopics/west_nile_fever/West-Nile-fever-
maps/Pages/historical-data.aspx).
 West Nile virus (WNV) fact sheet. Atlanta: National Center for Emerging
and Zoonotic Infectious Diseases, Centers for Disease Control and
Prevention; 2013
(http://www.cdc.gov/westnile/resources/pdfs/wnvFactsheet_508.pdf).
 ICMR Bulletin: West Nile Virus Epidemics: Lessons for India,
July,2002:Vol.32,7
• Paramasivan R et al: West Nile virus; the Indian scenario, Indian Journal
of Medical Research, September 2003: Vol.101-08
• Bodre P. Vijay et al: West Nile virus isolates from India: evidence for a
distinct genetic lineage, Journal of General Virology; 2007: Vol.88,875-84
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