Background: Swine influenza, also called swine flu, hog flu, and pig flu, is an infection caused by any one of the several types of swine influenza viruses. The World Health organization ( WHO) raised a worldwide pandemic alert for swine flu on June 11, 2009 that was a first of its kind in the past 70 years. In India, the index cases were reported from Pune, Maharashtra. We witnessed a recent outbreak in India during late 2014 and early 2015. Methodology: A retrospective study was carried out to describe the clinical profile and outcome of the confirmed cases of swine flu who were admitted at our center between December 10, 2014 and May 11, 2015. The cases were confirmed by reverse transcriptase polymerase chain reaction (RT-PCR) on respiratory specimens. Results: A total of 514 patients with symptoms suggestive of swine flu were tested for hemagglutinin type 1 and neuraminidase type 1 (H1N1) out of whom 88 were positive, which accounted for 17.12% positivity. The mean age was 31.15 years with a range of 11-90 years, with equal distribution among males and females (males: 45, females: 43). The epidemic peaked in the month of January (n = 44.50%). Fever (95.45%) was the most common clinical manifestation followed by cough (85.22%), breathlessness (51.22%), and myalgia (50%). The majority were in category C (59.09%) based on the severity of the illness. All the patients were hospitalized and treated with oseltamivir. Of all the positive patients, 39 (44.31%) were advised home isolation after discharge for 5-7 days in view of the mild disease. Hypertension, diabetes, existing lung diseases, cardiovascular diseases, smoking habit, alcohol consumption, and pregnancy were found to be the major risk factors. Women in the third trimester of their pregnancy were found to be at a higher risk. Our study had an overall mortality of 14.77% (n = 13). Mortality was higher among pregnant women (n = 1/6, 16.66%) compared to nonpregnant women (n = 5/37, 13.51%). Multiple organ dysfunction syndrome (MODS) and acute respiratory distress syndrome (ARDS) were the most common causes of death. Conclusion: Swine flu activity has come down significantly, with a single case being reported in the month of April and none in May in 2015 at our center.
Keywords: Epidemic, hemagglutinin type 1 and neuraminidase type 1 (H1N1), swine flu, Telangana
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Amaravathi KS, Sakuntala P, Sudarsi B, Manohar S, Nagamani R, Rao SR. Clinical profile and outcome of recent outbreak of influenza A H1N1 (swine flu) at a tertiary care center in Hyderabad, Telangana. Ann Trop Med Public Health 2015;8:267-71
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Amaravathi KS, Sakuntala P, Sudarsi B, Manohar S, Nagamani R, Rao SR. Clinical profile and outcome of recent outbreak of influenza A H1N1 (swine flu) at a tertiary care center in Hyderabad, Telangana. Ann Trop Med Public Health [serial online] 2015 [cited 2020 Aug 9];8:267-71. Available from: https://www.atmph.org/text.asp?2015/8/6/267/162649
The hemagglutinin type 1 and neuraminidase type 1 (H1N1) is a novel strain of influenza A virus that evolved by genetic reassortment. Following its emergence in March 2009 in Mexico, the H1N1 virus has spread rapidly throughout the world.  The H1N1 virus outbreak had previously occurred in India during the 2009 flu pandemic. The striking feature of the present epidemic that started in late 2014 was the rapidity of its spread and high mortality.  The disease spread, which was from April 2009 to August 2010 in the last pandemic, took just 2 months this time.  As of April 1, 2015, the disease had affected 34,351 people and claimed over 2,097 lives with the largest number of reported cases and deaths due to the disease that occurred in the states of Rajasthan, Gujarat, Delhi, Maharashtra, Madhya Pradesh, and Telangana. , The death toll rose to 2,223 by April 21, with Maharashtra registering the highest number of deaths of 485. 
With swine flu claiming 12 lives in the state of Telangana, the government declared high alert to contain further spread of H1N1 influenza on January 24, 2015.  In the current year from January 1 to April 6, 7,517 people have been tested out of whom 2,306 were found to be positive while the disease claimed 78 lives. 
This study was conducted to describe the clinical profile and severity of the recent influenza A H1N1 outbreak in the admitted cases at our center.
|Materials and Methods|
This is a retrospective study of all the confirmed cases of swine flu who were admitted in Osmania General Hospital, Hyderabad, Telangana, India between December 10 and May 11, 2015. All the cases were confirmed by reverse transcriptase polymerase chain reaction (RT-PCR) of the respiratory specimens including throat/nasopharyngeal/nasal swabs from ambulatory patients and broncheoalveolar lavage/tracheal aspirates of intubated patients at the Directorate of Institute of preventive medicine, Narayanguda, Hyderabad, Telangana, India. Detailed history, clinical manifestations, and investigations [complete blood count, renal function test, liver function test, electrocardiogram (ECG), and chest x-ray] were recorded. Clinical profile was analyzed with reference to age distribution, sex distribution, time distribution, severity, risk factors, complications, and outcome. The patients were placed in one of the following categories according to the guidelines provided by the Ministry of Health & Family Welfare: Seasonal Influenza A (H1N1) Revised on 11.02.2015.
All the patients were isolated and treated with oseltamivir. Broad spectrum antibiotics and mechanical ventilator support were given whenever needed.
Of the 514 patients attending our hospital with features suggestive of influenza-like illness during the study period, 88 were confirmed to have H1N1 infection. The mean age was 31.15 years with a range of 11-90 years and the maximum number of cases falling in the age group of 11-45 years (n = 54, 61.36%) as shown in [Table 1]. The cases were equally distributed among males (n = 45, 51.13%) and females (n = 43, 48.86%).
|Table 1: Agewise distribution
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The epidemic peaked in the month of January (n = 44, 50%) as shown in [Figure 1].
|Figure 1: Monthwise and genderwise distributions
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Fever (95.45%) was most the common clinical manifestation followed by cough (85.22%), breathlessness (51.22%), and myalgia (50%) as depicted in [Figure 2]. Two (2.27%) patients from the same locality had an uncommon manifestation of dysphagia. Most of the patients presented to the hospital within 7 days (94.31%). Of all the positive patients, 37 (42.04%) presented within 48 h and 46 (52.27%) between 3 days and 7 days.
|Figure 2: Clinical presentation
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Majority of the patients were under category C as shown in [Figure 3].
|Figure 3: Categorization of patients
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Among the 88 patients, 18 belonged to the medical/paramedical group where all (100%) had history of contact with a confirmed case of swine flu, whereas the contact history was present only in 10% among the others.
Of all the positive patients, 38 (43.4%) had comorbid conditions. Hypertension (17.04%), diabetes (15.9%), existing lung diseases (11.36%), cardiovascular diseases (10.22%), smoking habit (9.09%), alcohol consumption (6.81%), and pregnancy (5.68%) were found to be the major risk factors [Table 2]. Women in the third trimester of their pregnancy were found to be at a higher risk (five out of six pregnant females). The severity of the disease (category C = n = 29, 76.31%), occurrence of pneumonia (n = 33, 86.84%), and mortality (n = 10, 26.32%) were higher among patients with comorbid conditions.
|Table 2: Predisposing/comorbid conditions
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There was a predilection for lower lobes, with bilateral lower lobe pneumonia (n = 32, 36.36%) being the commonest finding on chest x-ray [Table 3].
|Table 3: Chest x-ray fi ndings
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Isolated bilateral pneumonia (25%) was the most common complication seen in our study group [Table 4]). Mortality was 100% with acute respiratory distress syndrome (ARDS), 75% with multiple organ dysfunction syndrome (MODS), 33.33% with acute kidney injury (AKI), and one patient developed myocardial infarction (MI) with cardiogenic shock and expired.
|Table 4: Complications
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All the patients were hospitalized and treated with oseltamivir. Of all the positive patients, 60 (68.18%) received broad spectrum antibiotics in view of the underlying pneumonia, 39 (44.31%) were advised home isolation for 5-7 days in view of the mild disease, and 11 (12.5%) were put on ventilator with a mortality of 100% in them.
Our study had overall mortality of 14.77% (n = 13). The deaths were equally distributed among the male (n = 7, 53.85%) and female (n = 6, 46.15%) patients. Deaths were more common in patients aged above 40 years (n = 9, 69.23%), with a mean age of 57.84 years. Ten (76.9%) patients had comorbid conditions. Mortality was high among pregnant women (n = 1/6, 16.66%) compared to nonpregnant women (n = 5/37, 13.51%). Bilateral pneumonia at the time of admission was present in nine (69.23%) patients. MODS (n = 6, 46.15%) and ARDS (n = 5, 38.46%) were the most common causes of death. One patient each had AKI and MI with cardiogenic shock as a complication.
A total of 514 patients with symptoms suggestive of swine flu were tested for H1N1. Of them, 88 were positive that accounted for 17.12% positivity, which was similar to the findings of a study conducted by Samara et al.  (17.35%) from Northern India (May 2009-May 2010) and Asmita et al.  (23%) from Kerala, South India (Aug 2009-Dec 2011).
The highest occurrence of H1N1 swine flu cases was in the month of January (50%) while the number of positive cases significantly reduced by April and was nil in May. This was similar to the findings of the study conducted by Mahender Singh et al.  from Rajasthan (September 2012-March 2013) where they had 33.2% of patients admitted in the month of January. Contrary to the conventional peak of the epidemic between September and December, we had a peak in the month of January, probably because of severe winter and unseasonal rains. Inadequate hygiene and crowded urban infrastructure have added to the problem.
The cases were equally distributed in both genders. This was similar to the results published in earlier Indian studies conducted by Asmita et al.  (M:F = 1:1), Chudasama et al.  (M:F = 1:1), and Puvanalingam et al.  (M:F = 1:1.25) from Kerala, Gujarat, and Tamil Nadu, respectively.
The majority were in the younger age group (11-40 years), accounting for 61.36% with a mean age of 31.15 years that was consistent with the findings of other studies, i.e., 29 years in the study of Samara et al.,  27 years in in the study of Chudasama et al.,  and 29 years in the study of Asmita et al.  unlike the conventional seasonal flu that is common in extreme ages. This may be due to some degree of preexisting immunity in them against antigenically similar influenza viruses.
History of contact with a confirmed case of swine flu was significant in medical and paramedical personnel.
Fever, cough, breathlessness, and myalgia were the most common symptoms observed in our population, which is similar to that in other studies. ,,,
We had two (2.27%) patients from same locality with dysphagia, which is an uncommon presentation.
Hypertension, diabetes, existing lung diseases, cardiovascular diseases, smoking habit, alcohol consumption, and pregnancy were the major risk factors. Women in the third trimester of their pregnancy were found to be at a higher risk. Similar findings were seen in other studies. ,,,,
Chest x-ray findings and complications were similar to that observed in other Indian studies. ,,
Our study had an overall mortality of 14.77 % (n = 13), which is slightly lower compared to the studies conducted by Sharma et al.  (18.44%) and Singh et al.,  (19.1%) probably because of the better facilities for rapid diagnosis and management. Though the incidence was more common in young individuals, the mortality was more in older individuals (mean age of 57.84 years). Mortality was higher among pregnant women (n = 1/6, 16.66%) compared to nonpregnant women (n = 5/37, 13.51%). But it is difficult to draw a conclusion as the number of pregnant women was small.
This is a retrospective study that included only hospitalized patients of a tertiary care institute, probably reflecting the tip of the iceberg as the milder forms would have been missed at the community level. So, the analysis may not reflect the actual distribution of the cases at the population level.
During the present epidemic at our center the incidence was higher in younger individuals with a peak in the month of January, having an equal distribution among the male and female patients. The mortality was, however, found to be higher in the older age group and in patients with comorbid conditions. Meticulous screening at the community level, prompt treatment and management of the complications by treating physicians, health education with regard to personal hygiene, and other preventive measures for identifying the subclinical cases and isolating them will go a long way in curtailing the recurrence of this epidemic. Now that the epidemic is on the wane, there should not be any complacence from the medical fraternity. It would be prudent to have continuous surveillance for any resurgence of the infection causing further epidemics/pandemics.
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Source of Support: None, Conflict of Interest: None
[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2], [Table 3], [Table 4]