Introduction
Influenza is an acute respiratory illness(2) caused by
the influenza viruses. These viruses have led to a number of outbreaks
and epidemics, causing significant morbidity and mortality globally.
Type A and B are the main human pathogens, with the former being very
common and associated with most large-scale and serious
outbreaks.(3) Type A virus possesses the ability to
periodically change the structure of its antigen (antigenic shifts and
antigenic drifts). . These antigenic shifts and antigenic drifts are
linked to annual pandemics. The incubation period of Type A influenza
virus is ~24-48 hours, after which symptoms such as
rapid onset of fever, headache, fatigue, and muscle pain, start to
appear .(4) These symptoms are associated with
manifestations of disease of the respiratory tract, including cough,
sore throat and rhinitis.(5) In these patients, a
common and dangerous complication is bacterial pneumonia. The mortality
rate is high and mainly attributed to refractory
hypoxia.(6)
The widespread H1N1, subtype influenza A virus, appeared first during
spring 2009 in Mexico from where it spread swiftly across the
globe.(7) On June 11, 2009, a phase 6 pandemic alarm
was declared by the World Health Organization (WHO), suggesting that the
21st century’s initial influenza pandemic had started.
The height of the local influenza outbreak had gone by in the majority
of the countries by the close of 2009.(8) The novel
H1N1pdm09 virus still circulates (with antigenic evolution and
variability) among the population, and plays a part in the usual
seasonal epidemics of influenza.(9) The global 2009
H1N1 virus led to extensive transmission among the United States and
other countries, and accounted for approximately 61 million cases,
274,000 hospital admissions, and 12,470 deaths.(10),(11)
Till now, internationally over 214 countries and territories have
reported lab-confirmed cases of H1N1, with 17,919 deaths(12), as well as enormous economic effect covering
both direct and indirect expense.(13) In a new case
series, the lag between the manifestation of the symptoms and starting
the treatments has been linked to unfavorable
results.(14) As regards the patients diagnosed with
influenza, longitudinal reviews are required to draw an estimation of
the fraction of cases that advance to death, respiratory failure, or
need extended hospitalization.(15) The earliest case
of swine flu (H1N1) in Pakistan, confirmed by laboratory testing, was
found on the 10th of August 2009, with occasional
cases reported every year thereafter. Pakistan was afflicted by the H1N1
epidemic from winter 2015 until February 2016, during when over 240
confirmed cases were reported.(1) But regarding
hospitalizations of the affected patients, its clinical manifestations
and outcomes, limited studies have been carried out in Pakistan. Our aim
was to evaluate the clinical manifestations and results in patients
admitted to the hospital having H1N1 influenza virus infection. The
objectives of this research were to evaluate the clinical features and
its outcomes in H1N1 influenza patients being treated at NWGH & RC,
Peshawar.