Swine flu and how to prevent it?
Swine flu is caused by influenza viruses that infect the respiratory tracts of pigs. Swine flu can last about one to two weeks in pigs that survive. In some instances, people have developed the swine flu infection when they are closely associated with pigs such as farmers, pork processors etc. Likewise, pig populations have occasionally been infected with the human flu infection. In most instances, the cross-species infections (swine virus to man; human flu virus to pigs) have remained in local areas and have not caused widespread infections in either pigs or humans. Unfortunately, this cross-species situation with influenza viruses has had the potential to change. In 2009, the first so called swine flu strain detected in Mexico, was termed H1N1 flu. It is termed so because it exhibits two surface antigens – H1 (hemoglobin type 1) and N1 neuraminidase type 1).
In fact, the pigs play a unique role as an intermediary host to new flu types because pig’s respiratory cells can be infected directly with human flu viruses. Consequently, pig’s respiratory cells are able to be infected with many types of flu and can function as a "mixing pot" for flu RNA segments.
Swine flu is transmitted from person to person by inhalation of droplets containing virus from person’s sneezing or coughing. It is not transmitted by eating cooked pork products. A new swine flu virus influenza A H3N2v has begun to infect humans. There have been many small outbreaks of H1N1 in many countries. In India, recently an outbreak of swine flu H1N1 has occurred. According to WHO estimates, 1200 people have died due to swine flu infection in 2015 outbreak in India.
Signs and symptoms –
The incubation period of swine flu from exposure to first symptoms is about one to four days with an average of two days. The signs and symptoms of swine flu are similar to most influenza infection.
Its common signs and symptoms are as follows –
- Fever (100 F or greater)
- Nasal secretions
- Fatigue, headache and body ache
- Sore throat
- Nausea, vomiting and diarrhea
Some patients may develop –
- Severe respiratory symptoms needing respiratory support
- Pneumonia (bacterial secondary infection)
The symptoms last about one to two weeks and can last longer if the person has a severe infection. The disease may be more dangerous if the patient is pregnant, have a chronic disease like emphysema, asthma, diabetes or a heart condition.
Swine flu is definitively diagnosed by identifying the particular antigens (surface proteins) associated with the virus type. Generally, this test is done in specialized laboratories.
The common complications of swine flu include the following –
- Worsening of chronic conditions, such as heart disease, diabetes and asthma
- Neurological signs and symptoms like confusion and seizures
- Respiratory failure
Most cases of swine flu H1N1 require treatment of symptoms only but there are some high risk cases which require special treatment. The patients are high risk if they –
- Are younger than 5 years of age, particularly children younger than 2 years
- Are 65 years and older
- Are pregnant or within two weeks of delivery, including women who have had pregnancy loss
- Are younger than 19 years of age and are receiving long-term aspirin therapy, because of an increased risk for Reye's syndrome, a rare but potentially fatal disease
- Have certain chronic medical conditions, including asthma, emphysema, heart disease, diabetes, neuromuscular disease, obesity, and kidney, liver or blood disease
- Are immuno-suppressed due to certain medications or HIV
The antiviral drugs like ostelamiver and zanamiver are sometimes prescribed to reduce the severity of symptoms but flu viruses can develop resistance to them. Therefore, to make development of resistance less likely, antivirals are reserved for patients at high risk of complications. Moreover, they should be used judiciously because of their high cost.
Swine flu H1N1 virus is spread exactly in the same way as other flu viruses. The virus is contained in tiny droplets, which come out when someone with infection sneezes or coughs. The droplets typically spread about three feet. These droplets typically remain suspended in the air for a while. Then they land on surfaces, where the virus can survive for up to 24 hours.
The virus is spread in the following manner -
- Any one who touches these surfaces can spread the virus by touching any thing else.
- The virus is spread, when an infected person who coughs or sneezes into one’s hands, touches other people or objects.
- Everyday items at home and in public places may have traces of the virus, which include food, door handles, remote controls, hand rails, paper money and computer keyboards. The individuals usually become infected by picking up the virus on their hands from contaminated objects and then placing their hands near their mouth or nose.
- It can be spread by breathing in the virus if it is suspended in airborne droplets.
The following measures may be adopted for the prevention of spread of virus –
- Good hygiene, such as hand washing and cleaning, is the most effective way of slowing the spread of flu.
- The infected people should be quarantined in the hospitals or at home till they become non-infectious (about 7 to 10 days after flu symptoms abate).
- One should avoid crowds, parties, and especially people who are coughing and sneezing. If you cannot avoid crowds or parties, try to remain aware of people around you and keep a distance of 6-foot with anyone coughing or sneezing. Do not reach for or eat snacks out of canisters or other containers at parties.
- Individuals who wear surgical masks may prevent inhalation of some H1N1 virus, but the masks may prevent only about 50% of airborne exposures and offer no protection against surface droplets. However, masks on H1N1 infected people can markedly reduce the spread of infected droplets.
Swine flu vaccine –
WHO recommend that people get a flu vaccine even during seasons when drifted viruses are circulating. It's because vaccination can prevent some infections and can reduce serious ailments that can lead to hospitalization and death. The flu vaccine has been designed to protect against three influenza viruses and some of these viruses may circulate later in the season. Trivalent influenza vaccine lends protection against swine flu H1N1, H3N2v and influenza B viruses.
The experts say that not everybody needs to take a swine flu vaccine. People in high-risk categories can take the shot. A vaccine-induced immunity lasts for eight to 12 months. The efficacy of swine flu vaccine is about 80%, but even then it is advisable because it lends protection to the vaccinated population from a potentially fatal disease.
The Centers for Disease Control and Prevention (CDCC), Atlanta, a US-based public health institute, recommends vaccination for children between 4 months and 5 years, those above 50 years, people suffering from chronic respiratory, cardiovascular problems, diabetes, pregnant women and health workers.