Chikungunya virus not likely to infect twice
Here's good news for anyone affected by
chikungunya this year: the virus is unlikely to infect them ever again.This has
been confirmed to TOI by virologists from AIIMS who said that unlike dengue,
which can be caused by four serotypes of the virus, the chikungunya virus has
only one serotype and hence the risk of repeated infection is minimal. “Only
those suffering comorbidities such as cancer remain at risk for repeated
infection due to their lower immunity,“ said Dr Lalit Dar, professor of
microbiology , AIIMS, on Friday .
Explaining
why chikungunya was so widespread this year after the outbreak a decade ago if
the virus was incapable of repeat infection, virologists said there was now a
large population that had not been affected in 2006 as well as more patients
with compromising medical conditions. Dar pointed out that many people had come
to Delhi from other states since 2006. They had not been affected by
chikungunya. “ A significant number of children born since then are also
non-immune to the disease.This explains the higher incidence of chikungunya
this year,“ said Dar. According to a study published in `Virology Journal' in
2014 that analysed immunity in the population affected by chikungunya in 1991
in Thailand, infection with one chikungunya strain confers lasting natural
immunity , even against other strains.
AIIMS
tested 3,500 patients suffering from fever in the last two months. Of them,
nearly 2,000 (57%) were confirmed to be suffering from chikungunya. The
prevalence of dengue was found to be just 5%. Dr S K Sharma, professor and head
of medicine department, said in 10-11 patients they found co-infection of
dengue and chikungunya viruses.
AIIMS and
the National Centre for Disease Control were tasked with identifying the
chikungunya virus in circulation to ascertain whether mutations caused this
year's higher incidence and fatality .But the experts firmly believed that the
higher incidence was due to the large pool of non-immune population. “Fatality
is rare and seen only in patients with pre-existing illness. You cannot blame
chikungunya for the deaths,“ averred Dr M C Misra, director, AIIMS.
A
committee set up by Delhi government had also refused to attribute the deaths
to chikungunya. The panel reviewed the files of 13 patients who had died after
suffering from fever and declared none of them caused by chikungunya.In its
report, the committee listed co-morbidities such as sepsis, kidney injury and
pneumonia as complications that might have led to the deaths.
(TOI)
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