High risk of avian influenza in Africa

Lack if infrastructure, reluctant, delayed or poor reporting, inefficent diagnosis, rapid urbanisation, political conflict and sociocultural issues mean that avian influenza in Africa is a very real risk.

Folorunso Fasina and colleagues point out that there is little information about the highly pathogenic H5N1 virus in Africa, but that the Asian strain of the virus is rife across the continent because of urbanisation and altered farming techniques. And it is rapid urbanisation that is one of the main reasons for the increased risk of this disease as an estimated 60% of residents live in slums, where peri-urban poulrty production is the norm.

In these areas human and animal disease surveillance is weak, confounded by the problems of HIV and other infectious diseases, such as TB and malaria. When avian influenza hit Africa in 2006 it was not contained for several reasons - delayed official decisions, inexperience, lack of prompt intervention planning, poor preparedness, corruption, and hesitation by farmers to report outbreaks. Similar factors have led to its spread in Asia.

Farming conditions in Africa are similar to those in Asia and free-range poultry in rural areas is at less risk of acquiring the virus. However, with peri-urban and urban spread, the virus is known to be present across the continent. To date, 40 Africans are known to have been infected, with a 40% fatality rate.

As it is, seasonal influenza is grossly under-reported in Africa and as a result the often less apparently severe avian influenza is highly unlikely to be detected. The relatively small number of Africans reported as infected so far may give a false sense of security, but, as these authors point out, these cases portend grave danger for a continent that is unlikely to be able to cope with a pandemic and which continues with high-risk farming practices.

Their assessment is that the perceptions of farmers and the general population shows major gaps in knowledge and a gross downplaying of the risk involved. On top of this, the general public is often seriously misinformed by government as to the true nature of avian influenze - with concomitant public health implications because poultry is generally sold to the public with no inspection practice in place.

Avian influenza is still circulating in Asia in domestic poultry and as a result of this prolonged circulation, has mutated into a variety of strains. The strain that is prevalent in Africa has particularly worrying characteristics, including spread by the respiratory rather than the faecal route, an ability to survive high temperatures and a gene mutation that is associated with high pathogenicity in mammals as well as in humans.

The WHO has identified five priorities in fighting avian influenza - reduced human exposure, strengthened surveillance, intensified rapid containment, enhanced response capacity, and coordinated global research. But Africa is unlikely to be able to accomplish all these goals.

The Asian strain of highly pathogenic H5N1 contiunues to ravage the African continent and there are continuing reports of new outbreaks, although some countries do claim to be free of the virus. Each African country needs to realistically assess its status, carry out active surveillance and provide more data. As the authors say, an uncontrolled spread of the virus in any country is a threat to the whole continent.

Fasina O et al. The Lancet Infectious Diseases 2007; 7: 696-697