Avian Influenza
Bird Flu, or more correctly Avian Influenza, is a pathogenic virus that normally only infects birds. Since 2003 however there have been occasional human cases, totaling 125 through November 2005. There exists a threat of more widespread transmission of this virus to humans. To keep our patients better informed, the following is an informative summary of Avian Influenza. It is certainly not meant to be all inclusive and for any specific information please consult either Dr. Cohen or Dr. Lerner.
Viruses consist of microscopic packets of genetic information surrounded by proteins. They do not have enzymes and have no synthetic ability on their own. Unlike other organisms they cannot synthesize lipids, carbohydrates or produce energy without the assistance of a host. They are parasites that require other “host” cells to reproduce.
Influenza is a group of viruses that infect the cells of the upper and or lower respiratory tract and cause acute respiratory infection and illness. These infections are usually accompanied by more widespread systemic symptoms such as fever, muscle aches, headache and weakness. Influenza viruses are grouped into either A, B or C categories depending on the characteristics of the virus. Influenza vaccine gives immunity against Influenza A which is the most common cause of flu in the winter months. Influenza viruses are further categorized based on the type of proteins on the surface either H (hemagglutinin protein that allows the virus to bind to and enter the host cell) or N (neuraminidase which allows the virus to be released from the host cell.)
Influenza outbreaks occur almost every year in the winter months and are due to the ability of the virus to change ever so slightly (mutate) so our antibodies are not as effective. Influenza vaccines or flu shots are effective in providing protection against the virus by boosting our antibodies against the virus. When there is a major change in the virus and the majority of people do not even have a minor degree of antibody protection, worldwide spread (pandemics) with severe symptoms and complications can occur. This is exactly what occurred in 1918 when the worldwide epidemic of Influenza A strain H1N1 spread throughout the world and infected a populace with no antibody protection. Severe pulmonary infections resulted in at least 40 million people worldwide dying, 675,000 of whom died in the
The initial event in influenza is infection of the respiratory tract with the influenza virus that is acquired from direct contact with the respiratory secretions of acutely infected individuals. Most transmission occurs via droplet spread from coughing or sneezing although hand to hand transmission is also possible. The incubation period ranges from 18-72 hours, after which systemic symptoms begin. The abrupt onset of fever, headache, severe myalgias, chills, cough and sore throat are the hallmarks of acute influenza infection. In uncomplicated influenza, the acute illness and systemic signs generally resolve over 2-5 days and the patient recovers completely within one week’s time. The most common complication of influenza is pneumonia though many other less frequent complications can occur.
Avian influenza or “bird flu” is the H5N1 strain of influenza A virus. It was thought that this strain only affected poultry until 1997 when 18 documented human cases occurred in
The current fear is that there may be a mutation in this H5N1 strain of influenza A which would allow it to be spread from human to human. If that would indeed occur, the virus would find a host population with virtually no immunity and it is feared similar consequences to the 1918 outbreak might occur.
Will getting a flu shot protect me from Avian Influenza? No, while getting the currently available flu vaccine will help with immunity for the current human strain, it will not confer immunity against the Avian Influenza H5N1 strain. Researchers are currently working on a vaccine against this strain. In the early stages of disease it may be difficult to differentiate Avian from regular influenza, but our health officials will alert us if an Avian outbreak is present.
If I must travel to the infected areas, what should I do for protection? One should avoid contact with poultry or any item that may have come in contact with poultry or their feces. Avoid markets where birds are sold. Avoid eating undercooked poultry. Refrigeration or freezing has no effect on the virus, though heat does rapidly kill the virus. Even if one were to consume infected poultry, proper heating should kill the virus. Since the virus can also be spread via hand contact, proper hand washing with soap and water or with portable alcohol based sanitizers should be frequently done. Common disinfectants such as alcohol, bleach or iodine will rapidly kill the virus.
Do any medications work against the virus? While the antiviral drugs amantadine (Symmetrel) and rimantadine (Flumadine) are both effective for treatment and for prophylaxis of most influenza A strains, neither have efficacy against the H5N1 avian strain. The two drugs osteltamivir (Tamiflu-an oral drug approved for treatment and prophylaxis) and zanamivir (Relenza-an inhaled drug only approved for treatment) both appear to be effective against influenza A H5N1, if started within 48 hours of symptom onset. It is unclear exactly how long treatment should go on if indeed there is an outbreak. The shelf-life of Tamiflu is 5 years. It is currently not recommended to get prescriptions of Tamiflu in advance of a possible outbreak. It is feared that inappropriate use might lead to drug resistance and the limited supplies of these drugs might be diverted from people who need them most.
We at LernerCohen Healthcare currently recommend avoiding travel to affected areas if at all possible. Strict hygiene and dietary precautions while in affected areas should protect travelers. Please discuss with your physician if you feel prescriptions for Tamiflu might be indicated in your particular circumstance. Every effort is being made both by the health department and the pharmaceutical industry to assure an adequate supply of Tamiflu should an outbreak occur.
We at LernerCohen Healthcare hope this informative article has been beneficial to your understanding of the current state of affairs concerning the possibility of an outbreak of Avian Influenza. Should you have further questions please call us and we will try to assist you with your concerns.
References:
The following links may also be helpful in monitoring the ongoing situation:
http://www.who.int/csr/disease/avian_influenza/en/
