Tuesday, December 29, 2009

Swine Flu hits Karachi

The total number of patients affected with swine flu in Karachi has increased to 52 after eight more cases were confirmed on Wednesday. The health department spokesman said the new cases were reported at the Aga Khan University Hospital (AKUH) where after necessary tests, it was confirmed that they were affected with swine flu, a new strain of the H1N1 virus. The total number of confirmed cases until Tuesday was 44, two of which were reported at the Services Hospital, while the remaining at AKUH, he added. He also said according to confirmed reports, so far three patients have died of this virus in the city.

Citizens of Pakistan are being gradually exposed to Swine Flu or Influenza A (H1N1) need not to be panicked but resort to all necessary precautions, doctors told on Wednesday. Besides due care towards general hygiene, they referred to the relevance of vaccination and anti-viral medicines.

Dr. Azhar Ibrahim particularly referred to GSK that has focussed in the development of vaccines for the influenza A (H1N1) strain of flu and the increased production of the anti-viral. The senior doctor said different pharmaceutical companies have started development and production of the new influenza vaccine and increased the production of antiviral medicines.

A person should seek medical care if they experience shortness of breath or difficulty breathing, or if a fever continues more than three days, said Dr. Azhar Ibrahim. He, however, urged people to realize extreme relevance of precaution and observed that there were several things that people in general and parents in particular must do to reduce the risk of catching flu, seasonal as well as variants.

Dr. ibrahim advised people to clean hands thoroughly with soap and water, or cleanse them with an alcohol-based hand rub on a regular basis (especially if touching the mouth and nose, or surfaces that are potentially contaminated). Children and elderly must be sensitized to avoid touching their mouth and nose. "We must also avoid close contact with people who might be ill and reduce the time spent in crowded settings if possible," said Dr. Ilyas Shamin.

What are the implications for human health?
Outbreaks and sporadic human infection with swine influenza have been occasionally reported.
Generally clinical symptoms are similar to seasonal influenza but reported clinical presentation ranges broadly from asymptomatic infection to severe pneumonia resulting in death. Since typical clinical presentation of swine influenza infection in humans resembles seasonal influenza and other acute upper respiratory tract infections, most of the cases have been detected by chance through seasonal influenza surveillance. Mild or asymptomatic cases may have escaped from recognition; therefore the true extent of this disease among humans is unknown.

Where have human cases occurred?
Since the implementation of IHR(2005)1 in 2007, WHO has been notified of swine influenza cases from the United States and Spain.

How do people become infected?
People usually get swine influenza from infected pigs, however, some human cases lack contact history with pigs or environments where pigs have been located. Human-to-human transmission has occurred in some instances but was limited to close contacts and closed groups of people.

Which countries have been affected by outbreaks in pigs?
Swine influenza is not notifiable to international animal health authorities (OIE, www.oie.int), therefore its international distribution in animals is not well known. The disease is considered endemic in the United States. Outbreaks in pigs are also known to have occurred in North America, South America, Europe (including the UK, Sweden, and Italy), Africa (Kenya), and in parts of eastern Asia including China and Japan.

What about the pandemic risk?
It is likely that most of people, especially those who do not have regular contact with pigs, do not have immunity to swine influenza viruses that can prevent the virus infection. If a swine virus establishes efficient human-to human transmission, it can cause an influenza pandemic. The impact of a pandemic caused by such a virus is difficult to predict: it depends on virulence of the virus, existing immunity among people, cross protection by antibodies acquired from seasonal influenza infection and host factors.

Is there a human vaccine to protect from swine influenza?
There are no vaccines that contain the current swine influenza virus causing illness in humans. It is not known whether current human seasonal influenza vaccines can provide any protection. Influenza viruses change very quickly. It is important to develop a vaccine against the currently circulating virus strain for it to provide maximum protection to the vaccinated people. This is why WHO needs access to as many viruses as possible in order to select the most appropriate candidate vaccine virus.

What drugs are available for treatment?
1 International Health Regulation (2005) http://www.who.int/ihr/about/en/ Antiviral drugs for seasonal influenza are available in some countries and effectively prevent and treat the illness. There are two classes of such medicines, 1) adamantanes (amantadine and remantadine), and 2) inhibitors of influenza neuraminidase (oseltamivir and zanamivir). Most of the previously reported swine influenza cases recovered fully from the disease without requiring medical attention and without antiviral medicines. Some influenza viruses develop resistance to the antiviral medicines, limiting the effectiveness of chemoprophylaxis and treatment. The viruses obtained from the recent human cases with swine influenza in the United States were sensitive to oselatmivir and zanamivir but resistant to amantadine and remantadine.

Information is insufficient to make recommendation on the use of the antivirals in prevention and treatment of swine influenza virus infection. Clinicians have to make decisions based on the clinical and epidemiological assessment and harms and benefit of the prophylaxis/treatment of the patient2. For the ongoing outbreak of the swine influenza infection in the United States and Mexico, the national and the local authorities are recommending to use oseltamivir or zanamivir for treatment and prevention of the disease based on the virus’s susceptibility profile.

Source: WHO


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