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ORIGINAL ARTICLE
Year : 2014  |  Volume : 27  |  Issue : 1  |  Page : 152-156

Study of swine flu infection in Menoufia governorate in years 2009-2010


Department of Chest Diseases, Menoufia University, Menoufia, Egypt

Date of Submission21-Mar-2013
Date of Acceptance18-Jun-2013
Date of Web Publication20-May-2014

Correspondence Address:
Asrar Helal Mahrous
MBBCH, Department of Chest Diseases, Menoufia University, Menoufia, 11160
Egypt
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/1110-2098.132790

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  Abstract 

Objective
The aim of this study was to evaluate the status of new H1N1 swine flu infection in Menoufia governorate during the years 2009 and 2010, with regard to the prevalence and mortality rates, and the most risky groups for infection and complications.
Background
Swine influenza is an infection caused by swine influenza virus that is endemic in pigs and was transmitted to humans.
Patients and methods
Data of H1N1-infected patients were collected from different hospitals (Chest, Fever and Menoufia University Hospital). Data were collected from Preventive Medicine Authorities in Menoufia governorate (2009-2010). A total of 400 patients were confirmed to be H1N1 infected using nasopharngeal swabs. Only files of 125 patients who were admitted to the hospital could be collected and studied regarding their name, age, sex, address, symptoms, signs, radiological findings, time of initiation of Tamiflu treatment, risk factors and outcome. All collected data were analysed to determine the prevalence of H1N1 infection in Menoufia governorate.
Results
The mean age of H1N1-infected patients was 30.9 ± 19.6 years. It was more common in urban areas than in rural areas. The presenting clinical features were tachycardia and fever. Radiograph was normal in 59.2% of the infected patients; 32.8% of the patients showed pneumonic patches on radiograph and 8% of the patients had a radiological picture of ARDS; 20% of the patients had chronic obstructive pulmonary diseases, 15% of the patients had cardiac diseases and 12% of the patients had diabetes mellitus; 96% of the patients improved and 4% died during the course of the illness. Only eight patients (6-4%) underwent mechanical ventilation.
Conclusion
Patients who received Tamiflu treatment within 48 h had better prognosis. Early suspicion of the infected cases is very important to decrease complications.

Keywords: H1N1, Menoufia, swine flu


How to cite this article:
Mansour OF, Baker RM, El Wahsh RA, Mahrous AH. Study of swine flu infection in Menoufia governorate in years 2009-2010. Menoufia Med J 2014;27:152-6

How to cite this URL:
Mansour OF, Baker RM, El Wahsh RA, Mahrous AH. Study of swine flu infection in Menoufia governorate in years 2009-2010. Menoufia Med J [serial online] 2014 [cited 2020 Feb 17];27:152-6. Available from: http://www.mmj.eg.net/text.asp?2014/27/1/152/132790


  Introduction Top


Influenza, commonly known as flu, is an infectious disease of birds and mammals caused by RNA viruses of the family Orthomyxoviridae, the influenza viruses. The most common symptoms are chills, fever, sore throat, muscle pain, headache (often severe), cough, weakness/fatigue and general discomfort. Although it is often confused with other influenza-like illnesses, especially the common cold, influenza is a more severe disease caused by a different type of virus. Influenza may produce nausea and vomiting, particularly in children, but these symptoms are more common in the unrelated gastroenteritis, which is sometimes inaccurately referred to as 'stomach flu' or '24-h flu' [1].

Flu can occasionally lead to pneumonia, either direct viral pneumonia or secondary bacterial pneumonia, even for persons who are usually very healthy. In particular, it is a warning sign if a child (or presumably an adult) seems to be getting better and then relapses with a high fever, as this relapse may be bacterial pneumonia. Another warning sign is if the person starts to have trouble breathing [2].

Typically, influenza is transmitted through the air by coughs or sneezes, creating aerosols containing the virus. Influenza can also be transmitted by direct contact with bird droppings or nasal secretions, or through contact with contaminated surfaces. Airborne aerosols have been thought to be the cause of most infections. Influenza viruses can be inactivated by sunlight, disinfectants and detergents. As the virus can be inactivated by soap, frequent hand washing reduces the risk of infection [3].

Seasonal risk areas for influenza: November-April (blue), April-November (red), and year-round (yellow).

Influenza reaches peak prevalence in winter, and because the northern and southern hemispheres have winter at different times of the year, there are actually two different flu seasons each year [4].

Swine influenza

Swine influenza was first proposed to be a disease related to human flu during the 1918 flu pandemic, when pigs became sick at the same time as humans. The first identification of an influenza virus as a cause of disease in pigs occurred about 10 years later, in 1930. For the following 60 years, swine influenza strains were almost exclusively H1N1. Then, between 1997 and 2002, new strains of three different subtypes and five different genotypes emerged as causes of influenza among pigs in North America. During 1997-1998, H3N2 strains emerged. These strains, which include genes derived by reassortment from human, swine and avian viruses, have become a major cause of swine influenza in North America. Reassortment between H1N1 and H3N2 produced H1N2. In 1999 in Canada, a strain of H4N6 crossed the species barrier from birds to pigs, but was contained on a single farm [5].

The H1N1 form of swine flu is one of the descendants of the strain that caused the 1918 flu pandemic. Apart from persisting in pigs, the descendants of the 1918 virus have also circulated in humans through the 20th century, contributing to the normal seasonal epidemics of influenza. However, direct transmission from pigs to humans is rare, with only 12 recorded cases in the USA since 2005. Nevertheless, the retention of influenza strains in pigs after these strains have disappeared from the human population might make pigs a reservoir where influenza viruses could persist, later emerging to reinfect humans once human immunity to these strains has waned [6].


  Patients and methods Top


In the present study, data of H1N1-infected patients were collected from different hospitals (Chest, Fever and Menoufia University Hospital).

Data were collected from Preventive Medicine Authorities in Menoufia governorate (2009-2010).

A total of 400 patients were proved to be H1N1 infected using nasopharngeal swabs. Only files of 125 patients who were admitted to the hospital could be collected and studied regarding their name, age, sex, address, symptoms, signs, radiological findings, time of initiation of Tamiflu treatment, risk factors and outcome.

All collected data were analysed to determine the prevalence of H1N1 infection in Menoufia governorate.

First, we studied the age of the infected patients to determine the age group that was most susceptible to H1N1 infection. We also studied the sex distribution of the infected patients.

Data about the residence of infected patients were collected to determine whether H1N1 infection was more common in urban areas or in rural areas.

All symptoms of infected patients were analysed according to their incidence.

Clinical examination was performed for all patients to determine the common signs in infected patients.

Radiograph was performed for all studied patients.

Risk factors in the infected patients were recorded and analysed.

We divided the patients studied into two groups according to the time of Tamiflu intake: before 48 h from onset of symptoms and after.

Also, mechanically ventilated patients were studied.

The clinical outcome of infected patients and comorbidity of patients who died were recorded in our study.

Analyses of our data were carried out through descriptive and comparative tables using the SPSS program (SPSS Inc., Chicago, Illinois, USA).


  Results Top


We found that the most common sign was tachycardia and fever. In our study, we found that radiograph was normal in 59.2% of the infected patients, 32.8% of. The present study was conducted for the evaluation of the new H1N1 swine flu infection in Menoufia governorate during the years 2009 and 2010, regarding its prevalence and mortality rates. We examined the available medical files of H1N1-infected patients. According to the records, we found that the total number of patients who were infected during 2009-2010 was 400 patients (on the basis of the results of a nasopharyngeal swab). However, files of only 125 patients who were admitted to different hospitals (Fever Hospital, Chest Hospital and Menoufia University Hospital) were available. In the present study, we found that the mean age of H1N1-infected patients was 30.9 ± 19.6 years. Also, we found that the occurrence of H1N1 infection was nearly equal in men and women and was more common in urban areas than in rural areas. By studying the symptoms in infected patients, we found that the most common symptom was fever (in 100% of patients). A total of 32.8% of the patients had pneumonic patches on radiograph and 8% of the patients had a radiological picture of ARDS. In our study, we found that 20% of the patients had chronic obstructive pulmonary diseases (COPDs), 15% of patients had cardiac diseases and 12% of patients had diabetes mellitus. In our study, 85.6% of patients received Tamiflu within 48 h of the start of symptoms. In our study, only eight patients (6-4%) underwent mechanical ventilation. In the present study, we found that 96% of the patients improved and 4% died during the course of the illness, five patients died. Only one patient had no comorbidity, whereas the others had the following comorbidities: the first patient had COPD, the second was diabetic, the third had rheumatic heart diseases, and three of them were smokers. In our study, we found that there was a highly significant difference between patients with different radiological findings in expectoration, drowsiness and headache. In our study, we found that there was a significant difference in the incidence of wheezing and pharyngitis between patients with different radiological findings. In our study, we found that all patients who died had a radiographic picture of ARDS [Table 1],[Table 2],[Table 3] and [Table 4].
Table 1: Sociodemographic criteria of the patients studied

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Table 2: Number and per cent distribution of different symptoms in the patients studied

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Table 3: Statistical comparison between patients with different radiological finding with regard to their symptoms

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Table 4: A statistical comparison between patients with different radiological findings with regard to their signs

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  Discussion Top


We tried to study the epidemiological data of H1N1 swine flu infection in Menoufia governorate during the years 2009 and 2010.

In the present study, we found that H1N1 infection was common around 27 years of age, its occurrence was nearly equal in women and men, and that the infection was more common in urban areas than in rural areas.

Martin and Jacobson [7], in their study on 426 patients in Spain, found that the mean age of swine flu-infected patients was 23.4 years, and 53.8% of the infected patients were men.

Kumar [8] in their study on 215 patients in Canada found that the mean age of H1N1-infected patients was 32.3 ± 21.4 years; they also found that 67.3% of the patients were women and girls, and 29.8% were children.

In our study, regarding the incidence of different symptoms, we found that all of the patients had fever, 92% had cough, 56% had expectoration and 92% had drowsiness.

Martin and Jacobson [7], in Spain, found that the most common symptoms of swine flu infection were fever (in 67.4% of the patients) and cough (69.5% of patients).

Domnguez et al. [9], in their study, found that the most common presenting symptoms of swine flu were fever (94% of patients), cough (92% of patients) and sore throat (66% of patients).

In our study, we noticed that all infected patients had tachycardia and 50% of the patients had pharyngitis.

Bakhshayeshkaram et al. [10], in their study on 540 patients in Iran, found that 90% of the patients had tachycardia and 80% of the patients had dyspnoea.

In the present study, radiological examination of patients revealed that the radiograph was normal in 59.2% of the patients, 32.8% had a pneumonic patch on radiograph and 8% presented a picture of ARDS.

Bakhshayeshkaram et al. [10] found in their study that 38.7% of the patients presented consolidation on chest radiograph.

In our study, when studying the comorbidity in the infected patients, we found that 20% of the infected H1N1 patients (25 patients) had chronic obstructive lung diseases, 15% (19 patients) had cardiac diseases and 12% (15 patients) of them had diabetes mellitus.

Bakhshayeshkaram et al. [10] found in their study conducted on 540 patients that 15% of the patients had COPD, whereas 9% of the patients had cardiac diseases.

Custa [11] found that 29% of the patients had COPD, whereas 28.2% of the patients had heart diseases and 20.9% of the patients had diabetes mellitus.

Patients who had a long-term lung disease such as COPD were more likely to suffer severe symptoms of H1N1 flu and were more likely to need hospital care. H1N1 flu makes COPD symptoms much worse.

In the present study, most of the patients received Tamiflu treatment within 48 h from the onset of symptoms.

Tamiflu treatment after 48 h

After 48 h of experiencing flu-like symptoms, Tamiflu usage will not be effective. The reason for this is that the virus will have already infected too many cells in the body. Before experiencing symptoms, it could have already been actively infecting cells for almost 2 days [12].

In our study, we found that 6.4% of the patients needed mechanical ventilation.

Domnguez et al. [9] in their study found that 56 out of 58 patients needed mechanical ventilation.

Kumar [8] in their study found that 81% of the patients needed mechanical ventilation.

This difference in the incidence of mechanical ventilation in swine flu-infected patients between our study and the Kumar [8] study could be explained by the fact that H1N1 infection started first in Mexico, where the disease was highly aggressive, and preventive and therapeutic measures were not well developed.

In our study, we found that 96% of the patients improved and 4% of them (five patients) died.

Domnguez et al. [9] in their study in Mexico found that the mortality rate was 41.4% of the infected patients.

Mortality in our study was lower than that reported by Domnguez and colleagues probably due to the high awareness to the disease and good preventive measures applied in Egypt, whereas Mexico was the first place where swine flu appeared.

In our study, five patients died; four of them had a comorbidity: the first had COPD, the second had diabetes mellitus, the third had RHD and three of them were smokers.

Aviram [13] in his study in Maricopa found that the most common comorbidities among H1N1 inpatient deaths were chronic lung disease (55.4%) and immune suppression (53.8%).

In our study, we found the following by a statistical comparison between patients with different radiological findings with regard to their symptoms.

Among patients who had a normal radiograph, 90% of them had cough and 32% of them had expectoration. However, among patients who had a pneumonic patch on radiograph, 45% of them had cough and 92% of them had expectoration. In contrast, patients who had a picture of ARDS on radiograph were almost symptomatic: 90% of them had expectoration and 100% of them had cough.

In the present study, we found that wheezing and pharyngitis had significant relation to the radiological picture.

Bacakoπlu et al. [14] in their study recommended that the presence of fever, dyspnoea with nonpulmonary symptoms and accompanying radiological alveolar opacities should be considered as pandemic influenza A (H1N1).

Abbo et al. [15] in their study on 157 patients found that dyspnoea was associated with an increased likelihood for radiographic lung abnormalities (P < 0.001), and hypoxaemia (P < 0.001) was also associated with radiological abnormality.

The Al-Nakshabandi et al. [16] study, including 179 patients, found that among patients with a normal CXR, 109 (94%) had fever. Among those with an abnormal CXR, 96.8% had fever, but they noticed that fever was not a determining factor for normal versus abnormal CXR, as the P-value was 0.327.

They also found that 94 (81%) of the patients who had cough had a normal CXR. Among those with an abnormal CXR, 59 (93.7%) had a cough. Therefore, cough appears to be a determining factor, with a P-value of 0.039. Among those with a normal CXR, 27 (23.3%) had a sore throat. Among those with an abnormal CXR, 25 (3%) had a sore throat, and therefore, sore throat appears to be a determining factor. There were seven (6%) patients with a normal CXR and dyspnoea. Among patients with an abnormal chest radiograph, there were three (4.8%) with dyspnoea. The correlation between dyspnoea and chest radiograph was not statistically significant (P=0.507) (2011) [16].

In the present study, we found that the radiological finding had a highly significant relation to the outcome, and all patients who died had a radiological picture of ARDS.

A study conducted by Aviram [13] on 179 H1N1 influenza patients found that 97 patients (54%) underwent chest radiography at admission; 39 (40%) of them had abnormal radiologic findings likely related to influenza infection and five (13%) of them 39 had adverse outcomes. Fifty-eight (60%) of the 97 patients had normal radiographs; two (3%) of them had adverse outcomes; they concluded that extensive involvement of both lungs, evidenced by the presence of multizonal and bilateral peripheral opacities, is associated with an adverse prognosis. Initial chest radiography may have significance in helping predict the clinical outcome, but normal initial radiographs cannot exclude adverse outcomes (2011) [13].


  Acknowledgements Top


Conflicts of interest

There are no conflicts of interest.

 
  References Top

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14.1Bacakoðlu D, Bar-Shai A, Rogowski O, Rosen G, et al. Comparitive study of swine flu symptoms. Radiology 2010; 255 :252-2529.  Back to cited text no. 14
    
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16.1Al-Nakshabandi Drexler JF, Helmer A, Kirberg H, et al. Determining symptoms for chest radiographs in patients with swine flu (H1N1). N Engl J Med 2009; 361 :674-6779.  Back to cited text no. 16
    



 
 
    Tables

  [Table 1], [Table 2], [Table 3], [Table 4]


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