WHO reports six human H5N1 avian influenza cases during past six weeks
According to a World Health Organization (WHO) summary and assessment Friday, from March 12 to April 26, 2013, there were a total of six new laboratory confirmed human cases with avian influenza A(H5N1) virus infection.
H5N1 Avian Influenza
Image/CDC
The cases were from the following countries: Bangladesh (1), Cambodia (1), Egypt (2 ) and Vietnam(2). The UN agency says that after investigation, the six cases are considered sporadic; however, more cases are likely in the future.
So far this year, Cambodia has reported 10 cases of the lethal virus in humans, resulting in eight fatalities. Health authorities say cases do not seem to be linked directly, and most had contact with sick poultry in their villages.
Since 2003, there have been 628 laboratory-confirmed human cases with avian influenza A(H5N1) virus infection have been officially reported to WHO from 15 countries, of which 374 died (approximately 60 %).
According to the WHO, the H5N1 virus subtype (different from the H7N9 strain circulating in the current China outbreak) – a highly pathogenic AI virus- first infected humans in 1997 during a poultry outbreak in Hong Kong SAR, China. Since its widespread re-emergence in 2003 and 2004, this avian virus has spread from Asia to Europe and Africa and has become entrenched in poultry in some countries, resulting in millions of poultry infections, several hundred human cases, and many human deaths.
The case fatality rate for H5N1 virus infections in people is much higher compared to that of seasonal influenza infections.
Clinically, in many patients, the disease caused by the H5N1 virus follows an unusually aggressive clinical course, with rapid deterioration and high fatality. Like most emerging disease, H5N1 influenza in humans is poorly understood.
The incubation period for H5N1 avian influenza may be longer than that for normal seasonal influenza, which is around two to three days. Current data for H5N1 infection indicate an incubation period ranging from two to eight days and possibly as long as 17 days. WHO currently recommends that an incubation period of seven days be used for field investigations and the monitoring of patient contacts.
Initial symptoms include a high fever, usually with a temperature higher than 38oC, and other influenza-like symptoms. Diarrhoea, vomiting, abdominal pain, chest pain, and bleeding from the nose and gums have also been reported as early symptoms in some patients.
One feature seen in many patients is the development of lower respiratory tract early in the illness. On present evidence, difficulty in breathing develops around five days following the first symptoms. Respiratory distress, a hoarse voice, and a crackling sound when inhaling are commonly seen. Sputum production is variable and sometimes bloody.
For more infectious disease news and information, visit and “like” the Infectious Disease News Facebook page
Looking for a job in health care? Check here to see what’s available
