Avian Influenza

• Symptoms in humans: Eye infection, cough, fever, sore throat, muscle aches, headache, pneumonia, acute respiratory distress, diarrhoea, vomiting and/or nausea [2].

• Worst of the worst outbreak (in poultry): In 2003; 150 million birds were dead [5].

• First human infection (H5N1 virus): 1997 - in Hong Kong, with a total of 18 cases, which left six dead [8].

• There were 390 human cases and 246 human deaths of Avian Influenza A (subtype H5N1) reported to World Health Organization (WHO) since 2003 up to 12 December 2008 [6].

• Even pigs, tigers, leopards, ferrets and domestic cats were the victims of H5N1 virus [1].

• The latest human case has been reported in Cambodia on 12 December 2008 (as of 15 December 2008) [4].

Avian influenza or more commonly referred as “bird flu”, a viral infection of animals. Once only confined birds, as the saying about the viruses goes “viruses that normally infect only birds and, less commonly, pigs” [5], the viruses have now found their way to humans (and other animals). However, first human infection case surfaced in 1997 in Hong Kong, while cases in tigers and leopards have been first reported in December 2003 in Thailand.  

Avian influenza infection among poultry manifests itself into two forms; low pathogenic form and highly pathogenic form. Poultry infection of low pathogenic form usually causes mild symptoms such as the lowered egg productivity or ruffled feathers. The one that causes the most severe impact is the highly pathogenic form, that is capable the spread the disease among poultries rather quickly. The virus will affect internal organs, causes disease and mortality within 48 hours. 

Migratory birds are partly responsible for the spread of Avian influenza viruses are believed to be transmitted to other poultry when these poultry come into contact with the faeces of waterfowl. The wild waterfowl are said to have been carrying all influenza A viruses for centuries without any sign of harm [5] . These migratory birds have the ability to spread H5 and H7 viruses to poultry. The virus H5N1, which has caused panic worldwide in 2003, belongs to H5 subtype. Both H5 and H7 subtypes are originally in low pathogenic form. However, these viruses are able to mutate into highly pathogenic form within few months when allowed to circulate in poultry populations. However, the 2003 outbreak has suggested that some of these wild migratory birds might be spreading the H5N1 virus in its highly pathogenic form [5]. 

According to WHO, H5N1 virus transmission among poultry will put human health at two main risks [5]: 

• Direct infection from poultry: Human will be infected by the virus when they are in direct contact with the infected poultry, faeces, objects which are polluted by the faeces and other parts of the infected poultry. Humans who consume infected poultry which are not properly cooked can contract viral infection. This infection will cause severe diseases, such as primary viral pneumonia and multi-organ failure, which may lead to death.

• Human-to-human infection: The virus may transform its viral protein coat that and transform into highly infectious form, and eventually infects human. This adaptation will lead to the possibility of H5N1 infection from human-human contact (i.e.: air by coughing and sneezing).  

WHO states that avian influenza is now at its in pandemic alert phase (“phase 3”) [7]. This means that there is “no or very limited human-to-human transmission” [7]. Experts also believe that we are now inching much closer towards another global influenza pandemic since 1968. 

Regardless of the alert phase, we should always practice good hygiene and proper cooking to protect ourselves from being infected. As H5N1 virus has sensitivity towards heat, cooking at minimum 70oC will definitely destroy the virus (if present). This means that 100% cooked food will pose no risk of infection. 

1. Centers for Disease Control and Prevention. (2008, May 28). Questions and answers about avian influenza (bird flu) and avian influenza A (H5N1) virus. Retrieved December 15, 2008, from http://www.cdc.gov/flu/avian/gen-info/qa.htm
2. Centers for Disease Control and Prevention, USA. (2008, May 23). Avian influenza A virus infections of humans. Retrieved December 15, 2008, from http://www.cdc.gov/flu/avian/gen-info/avian-flu-humans.htm
3. Juckett, G. (2006, September 1). Avian influenza: Preparing for a Pandemic. Retrieved December 15, 2008, from http://www.aafp.org/afp/20060901/783.html
4. World Health Organization (WHO). (2008, December 12). Avian influenza - situation in Cambodia. Retrieved December 16, 2008, from http://www.who.int/csr/don/2008_12_12/en/index.html
5. World Health Organization (WHO). (2005, December 5). Avian influenza frequently asked questions. Retrieved December 15, 2008, from http://www.who.int/csr/disease/avian_influenza/avian_faqs/en
6. World Health Organization (WHO). (2008, December 12). Cumulative Number of Confirmed Human Cases of Avian Influenza A/(H5N1) Reported to WHO. Retrieved December 15, 2008, from http://www.who.int/csr/disease/avian_influenza/country/cases_table_2008_12_12/en/index.html
7. World Health Organization (WHO). (n.d.). Current WHO phase of pandemic alert. Retrieved December 16, 2008, from http://www.who.int/csr/disease/avian_influenza/phase/en/index.html
8. World Health Organization (WHO). (2008, December 8). H5N1 avian influenza: Timeline of major events. Retrieved December 16, 2008, from http://www.who.int/csr/disease/avian_influenza/Timeline_08%2012%2008.pdf