Wednesday, November 2, 2011

Hantavirus: Possibility of human-to-human transmission cannot be ruled out

Syed Akbar
Hyderabad, Nov 1: The identification of the serotype of the Hantavirus
that is reported from parts of the State is essential to know if the
virus is capable of causing infection from person to person. There are
instances of a few of the Hantaviruses circulating in South American
countries spreading person-to-person infection. But there are no
medical records of the Hantaviruses present in North America causing
such infection.

The types present in Asian countries are quite different from those
circulating in the Americas. Whether the Hantavirus that had
reportedly infected a person in Karimnagar and three others in Nellore
is one of those already identified and belong to the Asian group or
had undergone mutation to become more virulent is not known. There are
no records of Asian groups spreading from person-to-person.
Scientists, however are divided over the person-to-person transmission
of the Hantavirus. They do not rule out the possibility, in case the
virus had mutated to achieve such capability.

For instance swine flu virus, which was originally transmitted between
pigs, became mutant to infect human beings and then it gain the power
to transmit from person to person. But scientists do not want to jump
to conclusion before studying the virus in detail. They however, agree
that the Hantavirus did not yet had its word, since it is a new and
emerging pathogen.

"Person-to-person transmission of Hantavirus has not been commonly
reported so far. About 21 species have been described in the
literature. Hantaviruses are described as emerging pathogens as newer
serotypes are being discovered in many areas non-endemic to them. The
Hantaviruses are the RNA viruses. The probability of mutation is
always higher in the
RNA viruses. Such mutational events help these viruses in their immune
evasion capacity," said Dr Sunit K Singh, senior scientist from the
Centre for Cellular and Molecular Biology.

A report in Lancet refers to a dentist in Bosnia and Herzegovina, who
developed HFRS after being injured with contaminated forceps during
tooth extraction in a patient with HFRS. The dentist had never been in
a forest and denied any contact with rodents. This case could be the
first evidence of possible human-to-human transmission of Hantavirus
in Europe.

A team of Argentine and US researchers investigating the 1996 Argentine
outbreak has found epidemiological evidence that "strongly suggests"
person-to-person transmission. Person-to-person transmission in North
America has not been reported. A few situations of Hantavirus
pulmonary syndrome in South America suggests person-to-person
transmission is possible.

The Centers for Disease Control and Diagnosis, USA, points out
"although person-to-person spread has not been documented with any of
the other
known Hantaviruses, we were concerned because we were dealing with a
new agent".

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