Published Date: 2012-10-05 18:04:35
Subject: PRO/EDR> Chikungunya (17): India
Archive Number: 20121005.1326566
CHIKUNGUNYA (17): INDIA
A ProMED-mail post
ProMED-mail is a program of the
International Society for Infectious Diseases
Date: Thu 4 Oct 2012
Source: Daily Mail [edited]
After dengue, it is the turn of chikungunya to strike fear in the city. The virus that causes chikungunya, the illness characterised by high fever and severe pain in the joints that afflicts scores of Delhiites every year, has mutated into a deadly strain, scientists have warned.
Delhi has already reported 6 cases of chikungunya so far this year , a figure likely to rise in the days ahead. In 2011 and the year before that, 54 and 33 cases of chikungunya [virus infection] were reported respectively in the Capital.
The dire warning comes from a group of scientists and doctors from the city-based International Centre for Genetic Engineering and Biotechnology, Vardhman Mahavir Medical College, Safdarjung Hospital and International Centre for Genetic Engineering and Biotechnology.
The scientists and doctors studied the chikungunya virus in Delhi for a year. "There is emergence of a distinct molecular signature within the virus strains ... leading to appearance of new subgroups and suggests a dynamic evolution of the virus, which may change the infection's intensity and clinical symptoms," one of the researchers said. "Delhi's samples showed a different signature from those seen in the reference strains and other strains from India reported since 1963 and the latest documented epidemic from 2005 onwards. Understanding the consequences of such changes in viral genomes is vital to prepare for any public health disaster," she said.
Scientists used blood samples drawn from more than 289 patients from Safdarjung Hospital, who were suspected to have chikungunya. All the patients, belonging to different localities of Delhi, showed classical symptoms of chikungunya [virus infection] such as high fever, joint pain, muscle pain and skin rashes.
The experts analysed the structural genes E1 and E2 in the chikungunya virus. "With respect to E1 gene, all the Delhi samples showed 15 variations," the scientist said. "Analysis of the E2 gene revealed 32 variations in the Delhi samples," she added. The scientist said that the number of cases of chikungunya had been grossly underreported over the years because doctors might have misdiagnosed it as dengue and because of non-reporting of suspected cases.
The chikungunya virus is transmitted to people by the bite of infected female mosquitoes called _Aedes aegypti_ and _Aedes albopictus_, 2 carriers which can also transmit other mosquito borne viruses, including dengue. These mosquitoes usually bite at dawn and dusk but may bite at any time during the day, especially indoors in shady areas.
Chikungunya has grown to pandemic levels globally [It is not endemic in the Americas. - Mod.TY]. In India, the infection re-emerged in 7 states in 2005 and, according to a 2010 report, it has spread to more than 18 states and Union Territories afflicting more than 3.7 million people.
Delhi witnessed a chikungunya outbreak between October and December 2010 just after an outbreak of dengue.
"Since its reemergence, the intensity of the infection has increased with every passing year with 45 per cent to 63 per cent attack rates in several areas during outbreaks. India is endemic to dengue fever and because of overlapping symptoms, chikungunya is generally mistaken to be the former resulting in misdiagnosis," she said.
[Byline: Neetu Chandra]
ProMED-mail from HealthMap Alerts
[It is not surprising that genetic difference in chikungunya virus have occurred in the 49 year span over which virus isolates were collected from Delhi and other parts of India. This biological and clinical consequence of the molecular changes that the researchers observed is not stated, and the indication that these changes may affect intensity and clinical symptoms is speculative. The statements that the virus has mutated into a deadly virus simply is without substantiation. No fatalities are mentioned. Rather, the "... more than 289 patients from Safdarjung Hospital, who were suspected to have chikungunya ... showed classical symptoms of chikungunya". The "deadly" statement may be a case of journalistic exaggeration.
Studies of genome changes can be very valuable, and argue for the establishment of virus repositories so that isolates can be compared over time and space. Since pathogenesis experiments to compare virulence of various strains by infecting humans are out of the question, the only alternatives are development of an animal model that mimics human disease or comparison of virus isolates and disease in individuals infected naturally. Publication of the above report in a peer reviewed scientific journal is awaited with interest. - Mod.TY
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