Avian influenza in humans – an update

Abstract

Despite control of the poultry outbreak by culling and sometimes vaccination, poultry outbreaks and sporadic cases in humans continue to occur in South East Asia and is spreading to Europe. The human disease is characterised by a rapidly progressive community-acquired pneumonia and frequently diarrhoea with leukopenia, lymphopenia and impaired liver functions. Virus can be detected in the intestine, spleen, serum, cerebrospinal fluid, in addition to the respiratory secretions. Acute encephalitis or acute gastroenteritis were occasionally reported as early manifestations. Most of the cases are caused by poultry-to-human transmission. Human-to-human transmission is still inefficient but has occurred in health care workers and family contact. In endemic areas, patients presenting as community-acquired pneumonia with a history of contact with sick or dead birds should be isolated, investigated and empirically treated for H5N1 infection. Infection control measures should include contact, droplet and airborne precautions. The globalisation of this avian epidemic by migratory birds and the crude fatality rate of 50% in humans have triggered a global response of preparedness for a coming influenza pandemic which may occur with genetic reassortment or mutations conferring the virus the capability of efficient human to human transmission.