Swine influenzaBernice Clark ▼ | Wednesday April 29, 2009 6:01PM ET
Swine flu or more precisely, swine influenza is a contagious acute respiratory disease of pigs. It is caused by one of several swine influenza A viruses. As in the case of some other contagious diseases, the swine influenza virus is spreading by direct and indirect contact, and aerosols. The disease is present at every time of the year, but the number of sick animals increases in fall and winter. It is a known disease; so many countries vaccinate swine against the virus.
It is less known fact that swine virus, so the scientists believe, have been originally introduced into pigs by humans. The problems is that pigs may be infected with more than one virus at the same time, and those viruses can mix and create a new type of virus, and that’s exactly what happened in Mexico. The new virus is called a "reassortant" virus and it carries the genes from all viruses that created it. That in turn means that virus can cause a disease in humans.
Since many parts of the world are rich with swine population, there were a few human infections with swine flu in the past. The symptoms are very similar to the symptoms of "normal", seasonal influenza, but that is not always the case. The doctors around the world reported different clinical pictures, from asymptomatic infections to pneumonia, and even death. Since the symptoms are similar to the symptoms of seasonal flu, some cases obviously are not reported, so it is hard to know precisely how many people were infected after the contact with pigs.
The people may get swine influenza after the contact with the infected pig, but the virus can spread by air, which means that human to human transmission is also possible. It is confirmed that virus dies at the temperature higher that 70 C (160 F), so it is safe to eat properly cooked swine meat or other swine products. Until the current epidemic, the disease was mainly restricted to North America, South America, United Kingdom, Sweden, Italy, Kenya, and parts of Asia including China and Japan.
In the current case, the human to human transmission (level 4 on the WHO scale) is severe enough for the WHO to give the warnings to all countries about possible pandemic. It is very difficult to predict where, how and how fast the new virus will spread because it is a combination of few types, it’s hard to predict how many people will travel to contagious areas and how many people is resistant to the virus.
At the moment, there are no vaccines against swine flu virus. Every influenza virus changes very quickly so it’s only possible to develop the vaccine against the current type. The good news is that there are some drugs that can help, and those are so called adamantanes and inhibitors of influenza neuraminidase. The bad news is that some viruses can develop a resistance to some types of drugs.
Who is in danger? As it is the case with seasonal influenza, everyone who visits affected areas and people with lower immunity is prone to the virus. It is important to notice that in the case of swine influenza the new virus attacks younger persons, while the ordinary influenza is dangerous for elderly people.
There are advices for protection against swine flu and those are very similar to advices related to a seasonal influenza. The contact with pigs, especially in the affected parts of the world should be minimized; good hygiene is a must, as well as properly cooked meal. Dead or sick animals should not enter the meat production, and during slaughter the workers must handle the animals with great care. If you must travel to affected areas cover your nose and mouth during travel with masks easily available in any shop with medical material. Try not to stay in large group of people such as restaurants, bars and cinemas. ■