Avian Influenza - Update May 2006

My first article on Influenza A H5N1 a.k.a Avian Flu a.k.a as Bird Flu was way back on 13th December 1997. It was in my tenth article for Berita MMA. My second was my sixty-fourth article on 24 August 2004. Today is the third time I'm writing on this topic.

We can infer two things from here. One, H5N1 or avian flu has been around for a long time. There were a lot of concern then and there is a lot more concern now. So what is the difference? Are we now in greater danger of a potential pandemic than we were before? The second is closer to home, I have been writing infrequently...this being my fourth article since 24 August 2004! Well although I may write less frequently because of my current work schedule, I have nevertheless been updating all my web sites, including all my cybermed articles as well as added another disease site - Dengue (DF) and dengue hemorrhagic fever (DHF).

Lets look at the current situation. Since January, 2004 WHO has reported human cases of avian influenza A (H5N1) in the following countries:

East Asia and the Pacific	Europe & Eurasia	Near East
Cambodia	Azerbaijan	Egypt
China	Turkey	Iraq
Indonesia
Thailand
Vietnam

Since December 2003, avian influenza A (H5N1) infections in poultry or wild birds have been reported in the following countries:

Africa	East Asia & the Pacific	South Asia	Near East
Burkina Faso	Cambodia	Afghanistan	Egypt
Cameroon	China	India	Iraq (H5)
Niger	Hong Kong (SARPRC)	Kazakhstan	Iran
Nigeria	Indonesia	Pakistan	Israel
Sudan (H5) (New! Apr 24)	Japan		Jordan
	Laos
	Malaysia
	Mongolia
	Myanmar (Burma)
	Thailand
	Vietnam
Europe & Eurasia
Albania	Austria	Azerbaijan	Bosnia & Herzegovina
Croatia	Czech Republic (H5)	Denmark	France
Georgia	Germany	Greece	Bulgaria
Hungary	Italy	Poland	Romania
Russia	Serbia & Montenegro	Slovak Republic	Slovenia
Sweden	Switzerland	Turkey	Ukraine
United Kingdom

From CDC Updates : "The avian influenza A (H5N1) epizootic (animal outbreak) in Asia and parts of Europe is not expected to diminish significantly in the short term. It is likely that H5N1 infection among birds has become endemic in certain areas and that human infections resulting from direct contact with infected poultry will continue to occur. So far, the spread of H5N1 virus from person-to-person has been rare and has not continued beyond one person. No evidence for genetic reassortment between human and avian influenza A virus genes has been found; however, the epizootic in Asia continues to pose an important public health threat.

There is little pre-existing natural immunity to H5N1 infection in the human population. If these H5N1 viruses gain the ability for efficient and sustained transmission among humans, an influenza pandemic could result, with potentially high rates of illness and death. In addition, genetic sequencing of influenza A (H5N1) viruses from human cases in Vietnam and Thailand shows resistance to the antiviral medications amantadine and rimantadine, two of the medications commonly used for treatment of influenza. This would leave two remaining antiviral medications (oseltamivir and zanamivir) that should still be effective against currently circulating strains of H5N1 virus. Efforts to produce vaccine candidates that would be effective against avian influenza A (H5N1) viruses are under way. However, it will likely require many months before such vaccines could be mass produced and made widely available.

Research suggests that currently circulating strains of H5N1 viruses are becoming more capable of causing disease (pathogenic) in animals than were earlier H5N1 viruses. One study found that ducks infected with H5N1 virus are now shedding more virus for longer periods without showing symptoms of illness. This finding has implications for the role of ducks in transmitting disease to other birds and possibly to humans as well. Additionally, other findings have documented H5N1 infection among pigs in China and H5N1 infection in felines (experimental infection in housecats in the Netherlands and isolation of H5N1 viruses in tigers and leopards in Thailand).In addition, in early March 2006, Germany reported H5N1 infection in a stone marten (a weasel-like mammal). The avian influenza A (H5N1) virus that emerged in Asia in 2003 continues to evolve and may adapt so that other mammals may be susceptible to infection as well.

Notable findings of epidemiologic investigations of human H5N1 cases in Vietnam during 2005 have suggested transmission of H5N1 viruses to at least two persons through consumption of uncooked duck blood. One possible instance of limited person-to-person transmission of H5N1 virus in Thailand has been reported. This possibility is being further investigated in other clusters of cases in Vietnam and Indonesia.

The majority of known human H5N1 cases have begun with respiratory symptoms. However, one atypical fatal case of encephalitis in a child in southern Vietnam in 2004 was identified retrospectively as H5N1 influenza through testing of cerebrospinal fluid, fecal matter, and throat and serum samples. Further research is needed to ascertain the implications of such findings. "

Appended below the current situation as for cases and deaths attributed to H5N1 virus. Case fatality rates are 33%-38% in countries like Turkey and Egypt and as high as 100% in Cambodia and Iraq .

The graph below shows the date of onset by countries. Clearly showing more and more countries have been affected in a shorter period of time.

Some positive steps have emerged. WHO and majority of the countries have put in place Pandemic Preparedness Plans in the eventuality of a pandemic. Although Malaysia is not listed here, we can view our National Influenza Pandemic Preparedness Plan (NIPPP) at http://dph.gov.my/survelans/NIPPP.htm . In addition a Preparedness Pandemic Plan for Industry or some call it Business Continuity Plan is available from this site. For further plans, guidelines etc...of course you can get it from yours truly website at http://www.vadscorner.com/h5n1.html.

Looking at the Influenza Pandemics of the 20th Century, we had the "Spanish Flu" in 1918 with 40-50 million deaths caused by H1N1; "Asian Flu" in 1957 with 2 million deaths caused by H2N2 and the "Hong Kong flu" in 1968 with 1 million deaths caused by H3N2. Is H5N1 the next pandemic flu virus? How many deaths will it cause? Do historical events, which show decreasing mortality reflect better care, public health awareness, better treatment and better preparedness?

The links to URL mentioned above are valid at the time of writing (6th May 2006).