Avian influenza is the latest epidemic to pose a serious threat to health across South East Asia after crossing the species barrier between poultry and humans.
VOL: 100, ISSUE: 06, PAGE NO: 28
Jason Beckford-Ball, BA, RMN, is assistant clinical editor, Nursing Times
Avian influenza is the latest epidemic to pose a serious threat to health across South East Asia after crossing the species barrier between poultry and humans. Like severe acute respiratory syndrome (Sars), which was first discovered in the southern Chinese province of Guangdong in mid-November 2002 and has killed more than 900 people to date, avian flu may only seem a concern to those living in Asian countries. However, cases of Sars have been reported in countries as widespread as Canada, South Africa and Indonesia, and four probable cases were reported in the UK. Experts fear that avian flu could pose a large threat to human health. What is avian flu?
It was believed that avian flu only affected birds until it first jumped the species barrier in 1997, killing six people and infecting 12 others in a densely populated area of Hong Kong. Only two types have been known to infect humans, and they are both a subtype of the influenza A virus known as H5N1, which caused the 1997 outbreak, and H9N2, which infected two more people in Hong Kong in 1999. The current outbreak of avian flu affecting South East Asia (Fig 1) is a strain of H5N1. Avian flu can pass from birds to humans, although the number of humans infected to date is low. It is believed that the human cases have mainly occurred as a result of contact with chickens or their waste, rather than through eating chickens or chicken eggs. Poor hygiene in South East Asian food markets, where many chickens are often kept together in cramped conditions, may be responsible. Birds excrete the virus in their faeces, which dries, becomes pulverised and can then be inhaled (Spinney, 2004). However, there is concern that the avian flu virus could mutate inside a human also infected with a common flu virus (because different influenza A viruses can swap genetic material and merge), creating a new strain that could pass from human to human (MacKenzie, 2003). However, it is possible that this human-to-human transmission may have occurred between the members of one family (see also Clinical news, p7). The fear is that the more widespread avian flu becomes in any host, the greater the chance of it ultimately mutating. This fear has given rise to the widespread culling of poultry in South East Asia because a new mutant virus could rapidly spread around the world. The spread of avian flu
The World Health Organization (WHO) says immediate action is needed to prevent a repeat of the 1918 flu pandemic, which killed an estimated 40 million people globally. Health officials from across Asia are holding urgent meetings to plan what they can do to halt the spread of avian flu. Experts say the only way to contain the virus is to continue destroying potentially infected birds. Millions have already been slaughtered. If this is unsuccessful and infected birds reach markets, there is a high probability of the virus spreading through the people who come into contact with these birds. Last week 18 cases had been confirmed and 14 people had died from the latest outbreak of avian flu. Human symptoms
The symptoms of avian flu in humans are similar to other influenza virus infections, and include: - Fever; - Malaise; - Myalgia; - Sore throat; - Cough; - Conjunctivitis (in some patients). In extreme cases life-threatening complications such as pneumonia, viral pneumonia and acute respiratory distress can develop. Treatment
It is unlikely that any common flu vaccination would provide protection against avian flu in humans - a new vaccine would need to be produced. Organisations such as the Health Protection Agency and WHO constantly monitor flu activity to see if any new strains emerge. If one does, then the development of a new vaccine is considered. A UK laboratory is one of three in the world working to develop a vaccine, which could be used if the disease began to spread between humans. Researchers at the National Institute for Biological Standards and Control, in Potters Bar, Hertfordshire, are ‘building’ the vaccine by combining avian and human flu genes. They isolate a cell from the bird flu virus and alter its genetic make-up to render it harmless. Genetic material is then taken from a human flu virus. The resulting combined virus then provides the basis for a vaccine (BBC, 2004). However, large-scale production of a vaccine would not begin unless there was evidence that the virus was going to spread widely in the human population. The drugs available for treating flu in humans include: - Neuraminidase inhibitors such as zanamivir and oseltamivir act on all influenza A viruses; - The antiviral drug amantadine is also effective against influenza A viruses. These drugs could be effective against avian flu provided they are given early in the development of the illness. They will probably not have been used in Asia so far because of the expense and the advanced stage of cases. WHO is recommending that the following groups at risk of avian flu in South East Asia be inoculated with seasonal flu vaccine (WHO, 2004a): - Anybody expected to be in contact with poultry or poultry farms suspected to be affected with avian flu, especially people involved in culling poultry and people working on poultry farms where avian flu has been reported or is suspected, or where culling takes place; - Health care workers involved in the daily care of known or confirmed human cases of avian flu. WHO is also recommending that vaccine is supplied to health care workers in areas where there are confirmed cases of influenza H5N1 in birds. The risk in the UK
Experts say the chances of people in the UK catching avian flu from birds is minimal. The risk of the virus being found in poultry is low. Live poultry or eggs have now been banned from being imported into the UK from Thailand. Thorough cooking of poultry (to at least 70°C) would kill any virus (Nursing Times, 2004). Advice for travellers The current advice given on the Department of Health’s website states that: ‘Although there is no restriction on travel to any of the areas where avian flu is being reported, travellers are advised to take sensible precautions such as avoiding bird markets, farms or contact with live poultry’ (DoH, 2004). WHO’s advice is: ‘WHO does not at present recommend any restrictions on travel to any country currently experiencing outbreaks of H5N1 avian infection in poultry flocks, including countries which have also reported cases in humans. ‘At this time, WHO recommends that travellers to areas experiencing outbreaks of this disease in poultry should avoid contact with live animal markets and poultry farms. Large amounts of the virus are known to be excreted in the droppings from infected birds’ (WHO, 2004b). Implications for nurses
As the threat of avian flu is a newly emerging and continually evolving phenomenon, it is important that any nurses working in travel health keep themselves up to date with the latest developments. If the present outbreak of avian flu were to mutate into a human pathogen, a vaccination programme might be instituted. However, currently there is no specific vaccine available for this type of flu. As outlined in the above advice for travellers, nurses should advise anyone travelling to South East Asia to avoid all poultry markets or areas where poultry is processed (Fitfortravel, 2004). As with other health scares, if the epidemic does continue to spread it is inevitable that some people will panic (Crouch, 2003). It is crucial that primary contact nurses, such as those in A&E departments or working for NHS Direct, understand the implications of avian flu and can allay people’s fears. Conclusion
Although avian flu has not spread to the UK, it is still an issue for people wishing to travel to or from South East Asia. WHO has warned that the virus has the potential to mutate into an ‘efficient and dangerous human pathogen’ that could be more serious than Sars. Nurses, especially those who are involved in giving travel advice, need to be aware of the potential danger that avian flu poses to travellers and should keep themselves up to date with the latest developments in this area. This article has been double-blind peer-reviewed.