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Bird Flu FAQ:
How is Human Influenza A (H5N1) and Pneumonia treated?
We have purposely left this page with some detailed medical terminology to make cross-referencing and further study easier for you.
The Clinical Findings
Hospitalized patients suffering from the human influenza A H5N1 have had fever and influenza-like symptoms. Most have had lower respiratory problems including the cough. The incubation period for the disease ranges from 2 to 17 days with the average period being 3 days. Diarrhea, abdominal pain and vomiting have also been complications. [Ref:1-5]
Pneumonia
Patients with human influenza A (H5N1) usually develop lower respiratory symptoms early in the disease process. Nearly all patients develop pneumonia (see note below). Patients go from flu-like symptoms toward respiratory failure. In one study, the time from the onset of the disease till acute respiratory distress syndrome set in was six days. Studies suggest that the H5N1 disease causes viral pneumonia with limited secondary bacterial pneumonia or infection. [Ref:3, 6]
Treatment
The treatment for human influenza A (H5N1) has at this point been mostly supportive. The majority of hospitalized patients require early ventilator support (usually within 48 hours of admission). They are typically started on both broad-spectrum antibiotics and Antivral agents. Corticosteroids, though widely used, have not shown clear clinical benefit. Similar to other influenza infections, early administration of antiviral agents is necessary since administering Antivirals late in the illness provides little benefit. [Ref:1, 2, 6-7]
The oral neuraminidase inhibitor oseltamivir (commercialized as Tamiflu) appears to be the most useful agent. Although 5 days of therapy is considered adequate for treating mildly symptomatic patients early in the disease process, higher doses may be needed for a longer duration in more severe infections.
The optimum dose and duration has not been prospectively studied, and the dose should be adjusted for renal disease. The inhaled neuraminidase inhibitor zanamivir (commercialized as Relenza) has been used in animal models with some success; however, it has not been studied in humans.
Drug-resistant human influenza A (H5N1) has recently made the news with case reports of oseltamivir-resistant (Tamiflu-resistant) infections, primarily in Vietnam. This is significant because the older antiviral M2 inhibitors, amantadine and rimantadine, are ineffective against this organism. Should human influenza A (H5N1) develop widespread resistance, the pharmacologic treatment options would be severely limited. [Ref:2, 6, 8]
Future considerations
A major concern is a mutation of avian influenza A (H5N1) that would allow
sustained human-to-human transmission. An antigenic shift (change in the virus)
in avian influenza A (H5N1) that allows direct human-to-human transmission could
spark the next global influenza pandemic. Because human immune systems have had
little exposure to avian influenza A (H5N1), it is plausible that direct
human-to-human transmission of a new viral genome (Sum total of genetic material
of a virus ) would lead to widespread infection and high mortality.
(Currently, laboratory-confirmed human influenza A [H5N1] infections that are
symptomatic have an approximately 50% mortality rate.)
It is clear that prevention of the disease and thus a possible human pandemic is of great importance and focus. Some critics suggest too much time, effort and money is being spent. However, the global health care system has already benefited from the additional work. And, although there are currently no commercially available influenza A (H5) vaccines available for humans, several are under investigation.
NOTE: Pneumonia – What it is and how to prevent it.
Pneumonia is a common lung infection that affects millions of people each year. Pneumonia is characterized by an inflammation of the lungs caused by a bacteria, virus, or fungus. Pneumonia can be mild, moderate, severe, or even fatal. Although there are no generally effective treatments for most types of viral pneumonia, a vaccine is available for bacterial pneumonia. The pneumococcal vaccine protects against 23 types of pneumococcal bacteria populations and is effective in approximately 80 percent of healthy adults. A bacterial vaccine is generally given just once although revaccination can be given every 3-5 years for high-risk groups.
Because there is no vaccine for viral pneumonia such as that caused by influenza A H5N1, an influenza vaccine and a bacterial pneumonia vaccine should be discussed with your doctor. What some experts are saying is simply, it probably won’t do any harm to have a pneumonia vaccine as well.
References:
- 1) World Health Organization. Avian influenza (‘‘bird flu’’) fact sheet.
- 2) Beigel JH, Farrar J, Han AM, et al. Avian influenza A (H5N1) infection in humans. N Engl J Med. 2005:353: 1374–1385.
- 3) World Health Organization. How do people become infected?
- 4) Yuen KY, Chan PK, Peiris M, et al. Clinical features and rapid viral diagnosis of human disease associated with avian influenza A (H5N1) virus. Lancet. 1998;351:467–471.
- 5) Hein TT, Liem NT, Dung NT, et al. Avian influenza A (H5N1) in 10 patients in Vietnam. N Engl J Med. 2004; 350:1179–1188.
- 6) Moscona A. Neuraminidase inhibitors for influenza. N Engl J Med. 2005;353:1363–1373.
- 7) World Health Organization. WHO Rapid Advice Guidelines on pharmacological management of humans infected with avian influenza A (H5N1) virus.
- 8) Stephenson J. Drug-resistant avian flu. JAMA. 2005;294:2423.
Poll Results: Our
Quick Poll for February asked, "Have you considered or gotten a
pneumonia shot?"
Yes : 73.7%
No : 26.3%
Some 900 votes from various countries.
Next: » Pets and Animals - Can my dog or cat get H5N1, symptoms?
All Articles in this series:
» 1) Bird Flu and me - facts, risks, can I get it and can I stop it?
» 2) Basics on Bird Flu - What it is, history, what is a pandemic?
» 3) How is human influenza A (H5N1) and Pneumonia treated?
» 4) Pets and Animals - Can my dog or cat get H5N1, symptoms?
» 5) Summary - what are the plans, costs and what can I do?
» 6) Preventing viral infection spread - important tips.
» 7) Definitions for H5N1, avian or bird influenza.
Flash Presentation:
» Need a better understanding of the Bird Flu spread?
A very illustrative presentation that gives a graphic demonstration of the
world-wide spread of H5N1 from the Sydney Morning Herald. (opens in a new
window)