Clinicoepidemiological analysis of post pandemic emergence of Influenza A (H1N1) infection, in a tertiary care hospital-A retrospective analysis

Abstract

Background of the study- A novel influenza
A (H1N1) virus resulting from quadruple re
-assortment emerged in Mexico on March
2009 and emerged as pandemic, rapidly
spreading across about 178 countries with
significant mortality. WHO announced the
onset of post pandemic period on August
2010 with request to nations to have a
close surveillance.Aim of the study- To
analyze clinical and epidemiological data
from influenza A (H1N1) infection positive
cases, in and around Chennai city, in the
post pandemic period.Materials and Methods
-Throat swabs were collected from all
the patients who presented with signs and
symptoms suggestive of flu, during the
study period (July 2011 to June 2012) and
the samples were tested for H1N1 influenza
virus by RT-PCR method.Results -
Out of 318 cases tested, 32 (10.06 percentage
) cases were positive for Influenza
A (H1N1), with majority of the patients belonging
to the age group of 21-30 yrs
(59.37 percentage).Females (59.37 percentage)
were more commonly
affected than males (40.63 percentage).
10 of the positive cases(31.25 percentage)
were seen in people who were
living in closed community, 13 of the
positive cases(40.62 percentage)
occurred in health care personnel and all
the positive cases were clustered during
the period of April and May 2012 . Most
common clinical symptom was fever
(96.87 percentage) followed by cough
with expectoration (71.87 percentage)
and the most common combination of
symptoms were fever, sore throat ,cough
(15.63 percentage).Conclusion- Our
study showed, localised outbreak of pandemic
Influenza A (H1N1) that had occurred
in summer months of post pandemic
period, predominantly affecting
young adults, exhibiting acute, mild self
limiting illness. The study emphasis on
continued surveillance ,vaccination and
clinical management during the post pandemic
period.