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“COLOMBO, June 16 (Reuters) - Sri Lanka has identified its first case of the H1N1 flu virus in a young patient who arrived from Australia over the weekend, the government said on Tuesday.”We have detected the first swine flu case in Sri Lanka. He is an 8-year-old Sri Lankan living in Australia. He has come to Sri Lanka via Singapore with a family of five. Only he has tested positively for H1N1 and is being treated," Health Minister Nimal Siripala De Silva told reporters.”
The swine flu virus, also known as H1N1 virus now has invaded into Sri Lanka.It was first reported from US and now spreading rapidly all over the world. It is a mixture of swine, bird and human viruses and according to the World Health Organization currently there are approximately 165 people have died due to this H1N1 virus and over 37,000 victims are reported world wide.
What is Swine flu?
Swine flu is a viral disease which infects the respiratory tract of pigs (swine) , and results nasal secretions, barking-like cough, decreased of appetite and inactive behavior which are the most similar symptoms in human flu. Swine flu can last for 1 to 2 weeks in pigs that are able to survive. In 1930 the Swine flu virus was first isolated from pigs in US. The people who are closely associated with pigs like farmers, pork processors infected by swine flu virus in a number of instances and also occasionally the pigs infect by human flu. But these cross species infections between humans and pigs remained in local areas not turning into epidemic level. But these influenza viruses have the potential to be changed into new strain. So scientists think the cause for the epidemic in 2009 is a new swine flu viral strain and it is termed as H1N1 virus because the infected people exhibits two main surface antigens called H1(hemagglutinin type 1) and N1(neuraminidase type1).
Why is swine flu now infecting humans?
Researchers reveal two main series of events can lead swine flu (also bird flu) becoming a major cause for influenza illness in humans.
First, the influenza viruses (types A, B, C) are enveloped RNA viruses with a segmented genome. Segmented genome means that the viral RNA genetic code exists as eight different R
NA segments, not as a single strand of RNA, in the influenza viruses. A human (or bird) influenza virus and swine flu influenza virus can infect a pig respiratory cell simultaneously. In RNA replication, mistakenly some RNA strands of human influenza virus can be getting enclosed inside the enveloped Swine influenza virus. As an example, after above incident one cell could contain eight swine flu and eight human flu RNA segments. Then the total number of RNA types in one cell would be 16. Four of them came from swine influenza virus and other four from human influenza virus. Then those RNA segments could be arranged into one particle by making a viable eight RNA segmented flu virus from the 16 available segment types. In this new subtype of virus, there may be various combinations of RNA segments, thus it is called as antigenic shift and it may has the preferential ability to infect humans but it shows some unique features of swine influenza virus.
Consider this example. If a cell becomes infected with human influenza, swine influenza and bird influenza viruses, it is possible to include RNA strands from birds, swine, and human influenza viruses into one virus. (For example, it is possible to produce a viable eight-segment new type of flu viral genome with three bird flu, three swine flu, and two human flu RNA segments).
Small changes within an individual RNA segment which result minor changes in the virus are called as drift. But this takes a long time (usually years) to produce enough minor changes that cumulatively change the virus' antigenic makeup.
Second reason is the unique role of pigs as an intermediate host to new flu types because respiratory cells of pigs can be infected directly with bird, human, and other mammalian flu viruses. Bird flu viruses usually infect the gastrointestinal cells of many bird species and are spread by bird feces. Pigs can pick these viruses up from the environment and it seems to be the major way that bird flu virus RNA segments enter the mammalian flu virus population.
What are the symptoms of swine flu?
Swine flu symptoms are similar to most influenza infections just like fever (100F or greater), cough, nasal secretions, headache, with fatigue is very common in most infected individuals. Some patients also get nausea, vomiting, and diarrhea. Patients can get pneumonia due to bacterial secondary infection .Death often occurs from secondary bacterial infection of the lungs. Therefore appropriate antibiotics should be used in these patients. The usual mortality rate for typical influenza A is about 0.1%. Swine flu in Mexico (as of April 2009) has a mortality rate of about 6%, but it is far too early to predict the true mortality rate because there are new infections being reported in world wide.
How is swine flu diagnosed?
The presumptive clinical diagnosis of Swine flu is done by considering the patient’s history of association with people shown above symptoms. Generally, a quick test (nasopharyngeal swab sample test) is done to check if the patient is infected with influenza A or B virus. Most of the tests can differentiate A and B types. The test can be negative or positive for type A and B. If the test is positive for type B, the flu is not likely to be swine flu (H1N1). If it is positive for type A, the person could have type A flu strain or swine flu (H1N1). Swine flu (H1N1) is securely diagnosed by forming a particular antibody-antigen reaction. In general, this test is done in a specialized laboratory and it is not done in hospital laboratories.
The following case definitions are developed by the WHO for the purpose of reporting probable and confirmed cases of swine influenza A (H1N1) virus infection.
Note-Without any edition, these facts are available here
Clinical case description
Acute febrile respiratory illness (fever >38°C) with the spectrum of disease from influenza-like illness to pneumonia.
1. Suspected case of Swine Influenza
Individuals presenting with acute febrile respiratory illness (fever >38 °C) with the spectrum of disease from influenza-like illness (cough, sore throat, shortness of breath) to pneumonia
AND
One of the following epidemiological risk factors:
- Close contact* to a suspected case of swine influenza A (H1N1) virus infection while the case was ill
- Recent travel to an area where there are confirmed cases of swine influenza A (H1N1)
*Close contact: having cared for, lived with, or had direct contact with respiratory secretions or body fluids of a probable or confirmed case of swine influenza A (H1N1).
2. A Probable case of swine influenza A (H1N1) virus infection is defined as an individual with an influenza test that is positive for influenza A, but is unsubtypable by reagents used to detect seasonal influenza virus infection
OR
An individual with a clinically compatible illness or who died of an explained acute respiratory illness who is considered to be epidemiologically linked to a probable or confirmed case.
3. A Confirmed case of swine influenza A (H1N1) virus infection is defined as an individual with laboratory confirmed swine influenza A (H1N1) virus infection by one or more of the following tests:
- Real-time RT-PCR
- Viral culture
- Four-fold rise in swine influenza A (H1N1) virus specific neutralizing antibodies.
What treatment is available for swine (H1N1) flu?
In order to prevent influenza infections in humans, vaccination is been used. But still there is no vaccine available for Swine flu (H1N1).ongoing laboratory works in several countries may help to produce a vaccine for Swine flu (H1N1) later this year (2009). It is reported that the swine flu (H1N1) virus that has infected humans is resistant to the antiviral medications amantadine (Symmetrel) and rimantadine (Flumadine).But oseltamivir (Tamiflu) and zanamivir (Relenza) antiviral agents which are also used to prevent influenza A and B viruses can reduce the effect of Swine flu.
These drugs should not be used indiscriminately or they are not recommended if the Swine flu symptoms already have been present for 48 hours or more, because viral resistance can be occurred. Severe infected patients may require additional breathing support and treatment of other infections like pneumonia. In their interim guidelines, the U.S. Centers for Disease Control and Prevention (CDC) has suggested that pregnant females can be treated with those two antiviral agents.
How can swine flu be prevented?
There is no vaccine available right now to protect against swine flu. There are everyday actions that can help prevent the spread of germs that cause respiratory illnesses like influenza.
- Cover nose and mouth with a tissue when cough or sneeze. Throw the tissue in the trash after use it or dispose them properly.
- Wash your hands often with soap and water, especially after cough or sneeze. Alcohol-based hand cleaners or disinfectants are also effective.
- Avoid touching eyes, nose or mouth.
- Try to avoid close contact with sick people.
- If get sick with influenza, it is recommended to stay home away from work or school and limit contact with others to avoid infecting them.
Reporting of suspected swine influenza cases
All suspected cases of swine Influenza should immediately report the case to the Epidemiologist, Regional Epidemiologist/MOH by telephone (Epidemiology Unit emergency telephone number for: 011-4740491).
For additional information,
- http://www.cdc.gov/swineflu/
- http://www.cdc.gov/swineflu/clinician_pregnant.htm
- http://www.cdc.gov/travel/
- http://www.medicinenet.com/influenza/article.htm
- http://emedicine.medscape.com/article/219557-overview
References -
- Swine flu fact sheet published by Epidemiology Unit,Ministry of Healthcare and Nutrition,231, De Saram Place, Colombo 10,Sri Lanka.
- http://www.cdc.gov/socialmedia/h1n1/buttons.html
An article by - Bhagya Kodithuwakku.
