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Swine influenza

by Lesotho Times
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SWINE flu has been a popular topic of discussion and concern in our communities and many questions have been asked about the condition, including how it is transmitted, how one can suspect they have been infected and its treatment.

It must be emphasised from the onset that swine flu should not be a cause of alarm among people living in Lesotho. Everyone should remain calm in the face of the potential threat.

Swine influenza — also called H1N1 flu, swine flu, hog flu and pig flu — is an infection by any one of several types of swine influenza virus. The swine influenza virus is common throughout pig populations worldwide.

Transmission of the virus from pigs to humans is not common and does not always lead to human influenza. People with regular exposure to pigs are at increased risk of swine flu infection. The meat of an infected animal poses no risk of infection when properly cooked.

During the mid-20th century, identification of influenza subtypes became possible, allowing accurate diagnosis of transmission to humans. Since then, only 50 such transmissions have been confirmed. These strains of swine flu rarely pass from human to human.

Symptoms of swine flu in humans are similar to those of influenza and of influenza-like illness in general, namely chills, fever, sore-throat, muscle pains or body aches, fatigue,  severe  headache, coughing, weakness and general discomfort.

The 2009 outbreak has shown an increased percentage of patients reporting diarrhoea and vomiting.

Because these symptoms are not specific to swine flu, a differential diagnosis of probable swine flu requires not only symptoms but also a high likelihood of swine flu due to the person’s recent history and other specific tests that have to be carried out to confirm the diagnosis. For example, a diagnosis of confirmed swine flu requires laboratory testing of a respiratory sample (a simple nose and throat swab).

Swine influenza was first proposed to be a disease related to human influenza 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.

Influenza is quite common in pigs. The main route of transmission is through direct contact between infected and uninfected animals. These close contacts are particularly common during animal transportation. Intensive farming may also increase the risk of transmission, as the pigs are raised in very close proximity to each other.

The direct transfer of the virus probably occurs either by pigs touching noses, or through dried mucus. Airborne transmission through the aerosols produced by pigs coughing or sneezing is also an important means of infection. The virus usually spreads quickly through a herd, infecting all the pigs within just a few days.

People who work with poultry and swine, especially people with intense exposures, are at increased risk of infection. Vaccination of these workers against influenza and surveillance for new influenza strains among this population has therefore been recommended as an important measure.

Other professionals at particular risk of infection are veterinarians and meat processing workers, although the risk of infection for both of these groups is lower than that of farm workers.

Pigs are unusual as they can be infected with influenza strains that usually infect three different species: pigs, birds and humans. This makes pigs a host where influenza viruses might exchange genes, producing new and dangerous strains.

The most common cause of death is respiratory failure (difficult breathing). Other causes of death are pneumonia (infection of the lungs), high fever (leading to brain, spinal cord and nerve problems), dehydration (from excessive vomiting and diarrhoea and electrolyte imbalance). Fatalities are more likely in young children and the elderly.

Prevention of swine influenza has three components: prevention in swine, prevention of transmission to humans and prevention of its spread among humans.

Methods of preventing the spread of influenza among swine include facility management, herd management and vaccination.

Facility management includes using disinfectants and ambient temperature to control virus in the environment. The virus is unlikely to survive outside living cells for more than two weeks, except in cold (but above freezing) conditions, and it is readily inactivated by disinfectants.

The transmission from swine to human is believed to occur mainly in swine farms where farmers are in close contact with live pigs. Although strains of swine influenza are usually not able to infect humans this may occasionally happen, so farmers and veterinarians are encouraged to use a face mask when dealing with infected animals.

The use of vaccines on swine to prevent their infection is a major method of limiting swine-to-human transmission. Risk factors that may contribute to swine-to-human transmission include smoking and not wearing gloves when working with sick animals.

Influenza spreads between humans through coughing or sneezing and people touching something with the virus on it and then touching their own nose or mouth.

Swine flu cannot be spread by pork products, since the virus is not transmitted through food.

The swine flu in humans is most contagious during the first five days of the illness although some people, most commonly children, can remain contagious for up to 10 days. Diagnosis can be made by sending a specimen collected during the first five days for analysis.

Recommendations to prevent the spread of the virus among humans include using standard infection control measures. This includes the frequent washing of hands with soap and water or with alcohol-based hand sanitisers, especially after being out in public.

Vaccines against the new strains are being developed and could be ready soon.

Anyone with flu-like symptoms such as a sudden fever, cough or muscle aches should stay away from work or public transportation and should contact a doctor for advice.

Social distancing is another tactic.

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