Swine Flu

Swine Flu is a lung disease which affects the whole body and is contracted mainly by contact with the virus from droplets spread by coughing or sneezing.

The symptoms of swine flu in people are similar to those of regular influenza. Influenza (also known as the flu) is a contagious respiratory illness caused by flu viruses. It can cause mild to severe illness, and rarely leads to death. The flu is different from a cold as it usually comes on suddenly and may include ‘flu-like’ symtoms such as fever, lethargy, lack of appetite, coughing and aches and pains.

What is swine influenza?

Swine influenza, or swine flu, is a highly contagious acute respiratory disease of pigs, caused by one of several swine influenza A viruses. Morbidity tends to be high and mortality low (1-4 per cent). The virus is spread among pigs by aerosols, direct and indirect contact, and asymptomatic carrier pigs. Outbreaks in pigs occur year round, with an increased incidence in the autumn and winter in temperate zones. Many countries routinely vaccinate swine populations against swine influenza.

How many swine flu viruses are there?

Like all flu viruses, swine flu viruses change constantly. Pigs can be infected by avian, human and swine influenza viruses. When influenza viruses from different species infect pigs, the viruses can reassort and new ones emerge that are a mix of swine, human and/or avian influenza viruses. Over the years, different variations of swine flu viruses have emerged. Right now, there are four main influenza type A virus subtypes that have been isolated in pigs: H1N1, H1N2, H3N2, and H3N1. However, most of the recently isolated influenza viruses from pigs have been H1N1 viruses.

Can humans catch swine flu?

Swine flu viruses do not normally infect humans. Although swine influenza viruses are normally species specific and infect only pigs, they do sometimes cross the species barrier to cause disease in humans. However, sporadic human infections with swine flu have occurred. Most commonly, these cases occur in persons with direct exposure to pigs, such as children near pigs at a fair or workers in the swine industry.

Steps to help protect humans from swine flu

The steps taken to help protect an individual and prevent the spread of Swine Flu are the same as steps taken to prevent the spread of any flu:

– Arrange to have your annual flu injection, particularly if you suffer from a respiratory
disease such as chronic obstructive pulmonary disease (including emphysema and
chronic bronchitis) or asthma or pulmonary fibrosis. Although the current flu vaccine
does not protect against Swine Flu, it is very effective against the other strains that arealready circulating in Australia

– Wash your hands often – good hand-washing practices help prevent transmission of the virus

– Cover your nose and mouth with a tissue when you cough or sneeze and throw the tissue in the rubbish bin after use.

– Try to avoid close contact with people with symptoms of flu.

What is the role of face masks?

The routine use of face masks is not recommended unless advice from health authorities indicates. There is currently no need to stockpile face masks. Surgical masks should be worn by any person who is a suspected case of swine influenza to reduce their risk of infecting others. The risk of exposure is currently defined as being within 1 metre of a probable case for more than 15 minutes.

What are the different types of masks?

There have been discussions in media outlets regarding different types of face masks. The definitions below are for information only.
– Surgical masks are simple gauze mask which provide limited protection against airborne particles.

– P2 masks (also known as N95 masks in the United States) form an airtight seal around the nose and mouth. Some P2 masks have a respirator attached to increase ease of breathing. These masks are significantly more expensive than surgical masks. If used correctly, these masks offer a higher level of protection than surgical masks. Training is required to use these masks correctly. P2 masks are generally intended for use in acute health care settings (eg. hospitals). For overseas travellers to exposed regions and in particular the Americas they may wish to purchase masks while transiting international airports or visiting exposed areas. It is important that they take sufficient supply given that a mask needs to be replaced regularly and in
particular if moist.

Viral vocabulary

– Epidemic: A disease that occurs in an unusually high number of individuals in a community at the same time. The U.S. Centers for Disease Control says that to epidemiologists the terms "epidemic" and "outbreak" basically mean the same thing, and "outbreak" is often used to avoid sensationalism. The World Health Organization (WHO) says, "A disease outbreak is the occurrence of cases of disease in excess of what would normally be expected in a defined community, geographical area or season. An outbreak may occur in a restricted geographical area, or may extend over several countries. It may last for a few days or weeks, or for several years." SARS was considered an epidemic in Canada.

– Pandemic: A very widespread, often global, disease. According to the World Health
Organization, "An influenza pandemic occurs when a new influenza virus appears againstwhich the human population has no immunity, resulting in epidemics worldwide withenormous numbers of deaths and illness."

– Endemic: A disease that is constantly present, usually in low numbers in a population.

What are the symptoms of swine flu in humans?

The symptoms of swine flu in people are expected to be similar to the symptoms of regular human seasonal influenza and include fever, lethargy, lack of appetite and coughing. Some people with swine flu also have reported runny nose, sore throat, nausea, vomiting and diarrhea.

– Swine flu is caused by type A influenza virus and gives pigs the flu. Swine flu viruses cause regular outbreaks of flu in pigs but death is infrequent.

– Right now, there are four main influenza type A swine flu viruses that have been isolated in pigs: H1N1, H1N2, H3N2, and H3N1. Most of the recently isolated influenza viruses from pigs have been H1N1 viruses.

– Swine flu viruses do not normally infect humans. However, sporadic human infections have occurred. Most commonly, these cases occur in persons with direct exposure to pigs, such as children near pigs at a fair or workers in the swine industry. In addition, there have been documented cases of one person spreading swine flu to others

– The symptoms of swine flu in people are expected to be similar to the symptoms of regular human seasonal influenza and include fever, lethargy, lack of appetite and coughing.

How does swine flu spread?

Influenza viruses can be directly transmitted from pigs to people and from people to pigs. Human infection with swine flu viruses are most likely to occur when people are in close proximity to infected pigs, such as in pig barns and livestock exhibits at fairs.
Human-to-human transmission of swine flu can also occur. This is thought to occur in the same way as seasonal flu occurs in people, which is mainly person-to-person transmission through coughing or sneezing of people infected with the flu virus. People may become infected by touching something with flu viruses on it and then touching their mouth or nose.

What are the implications for human health?

Outbreaks and sporadic human infection with swine influenza have occasionally been 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.

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?

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.

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 patient.

There have been reports that oral antiviral medicines are out of stock at pharmaceutical wholesalers. The Pharmacy Guild has been in discussion with manufacturers and wholesalers and they are assured there is a substantial capacity in the supply chain to respond to increased demand for oseltamivir (Tamiflu®) and zanamivir (Relenza®).

Oseltamivir and zanamivir are Prescription Only Medicines. Consumers should be advised that seeking prescriptions and supply for the purposes of stockpiling these products is unwarranted. Distribution of oral antiviral medicines in a pandemic will occur via government pandemic stockpiles and will not occur through community pharmacies.

For overseas travellers to the northern hemisphere it is not uncommon at this time of year for those persons to have a prescription filled here for Tamiflu® or Relenza® and for that course to be taken if flu symptoms begin. With increased precaution amongst travellers there is an increased demand for these products. The key message for travellers is that, if they begin a course, they need to complete the five day course.

Is it safe to eat pork meat and pork products?

Yes. Swine influenza has not been shown to be transmissible to people through eating properly handled and prepared pork (pig meat) or other products derived from pigs. The swine influenza virus is killed by cooking temperatures of 160 degrees Farenheit or 70 degrees Celcius, corresponding to the general guidance for the preparation of pork and other meat.

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 isendemic in the United States. Outbreaks in pigs are also known to have occurred in North America, South America, Europe (including Britain, Sweden, and Italy), Africa (Kenya), and in parts of eastern Asia including China and Japan.

What other examples of swine flu outbreaks are there?

The most well known outbreak of swine flu was 1976 one among soldiers in Fort Dix, N.J. The virus caused illnesses in at least four soldiers and one death; all were previously healthy. The virus was transmitted in close contact at a basic training camp. It was thought to have circulated for a month and disappeared. The source of the virus, the exact time of its introduction into Fort Dix and factors limiting its spread and duration are unknown. The outbreak may have been caused by introduction of an animal virus into a stressed human population in close contact during the winter considered

As Presented by The Australian Lung Foundation

Sources: U.S. Centers for Disease Control and Prevention; World Health Organisation; and The Pharmacy Guild of
Australia (www.guild.org.au)