Last Tuesday I attended a lecture at a premier medical school given by two eminent microbiologists. The focus of the lecture was to educate the attendees about the flu and the risks of a possible worldwide infection (pandemic).

     Viruses cannot live outside the host. If human beings become immune to the virus, the virus will become extinct in humans. The smallpox virus killed over 300 million people in the 20th century. Through worldwide innoculations, the smallpox virus could no longer infect humans. Therefore, the smallpox virus is now extinct because there are no longer any human hosts it could infect.

     Viruses cause illness in humans by invading cells and replicating within the cells. The virus then spreads to other cells. Unless the immune system can control the virus, the virus will infect every cell and overrun the body. In some cases, death can result. Viruses are fought with the body’s natural immune systems or through vaccines. Vaccines stimulate the body’s immune system to produce antibodies to fight the disease. The viruses are isolated and then killed (inactivated) or weakened but live (attenuated). These killed or weakened viruses trick the immune system into an immune response namely the production of antibodies. The immune system does not distinguish between harmless dead or weakened viruses and a fully functioning virus. The immune response produces antibodies from the vaccine so when the fully functioning virus hits, it is met with antibodies which kills the virus before it can replicate throughout the body. Without the vaccine, the body cannot produce antibodies fast enough to stop the spread in the body of the virus.  

     The flu is a virus. A virus is smaller than bacteria or parasites. In fact, viruses are so small that if it were the size of a 3×5 index card, the cell would be the size of the old World Trade Center. The flu is classified as “A” type and “B” type. “A” types are subject to antigenic shifts. This means the virus has the ability to jump from animals to humans. A “B” type flu virus is a human virus that cannot jump from animals to humans. “A” type flu viruses can reside in birds, horses, pigs, whales, reindeer, seals and camels before jumping to humans.

     The 1918 Spanish flu killed 675,000 people in the US and 50 million worldwide. The high death toll could be attributed to the lack of knowledge about the flu. Health authorities believed the flu was a bacterial infection. Even if antibiotics existed in 1918, they would have been useless against the flu virus. Antibiotics are effective only against bacterial infections but are ineffective against viruses. The flu virus was not isolated until 1933. It is hard to believe how far medical science has come in the 90 years since the 1918 flu.

     The “A” flu virus has 16 different subtypes. There are currently 3 types of flu viruses circulating in the human population. These are H1, H2 and H3. The H1 and H3 strains were included in this year’s flu shots.

     The worry in public health circles is the H5 bird flu. There is currently no vaccine for humans for this flu virus. Various antiviral drugs may help if there is an outbreak. Currently, microbiologists report there has been no jump of the bird flu to humans. Of the 175 cases reported in humans worldwide, all had close contact with chickens or other birds. The bird flu has not yet appeared in the US. The scientific thinking is that the infection of the 175 people was caused by ingestion of infected birds without proper cooking. This released massive amounts of the bird flu virus into the bodies of the victims. Heat through proper cooking will kill the virus.

     The 1918 flu virus although extinct contained certain genetic proteins that made it lethal in humans. If that genetic protein combined with other flu viruses, a health problem could result. The best current scientific evidence is that the bird flu will not jump to humans but constant mutations in the virus requires significant monitoring.

     To summarize, 1) get your flu shot every year, 2) the bird flu is not currently a significant risk of jumping to humans from human contact and 3) chicken is safe to eat as long as it is cooked thoroughly. Chicken should be cooked thoroughly to avoid a bacterial disease called salmonella poisoning.