Six of the infected were reported to be from the same family. Four brothers and two cousins live in the small city of Abbotabad north of Islamabad. The other two, a man and his niece, are from the same area of the North-West Frontier Province.
The Associated Press reported that one of the brothers, Ishtiaq Muhammad, a veterinary doctor, contracted the disease after slaughtering chickens suspected of avian flu infection. "I was not aware that this was such a dangerous disease," Ishtiaq confessed to AP.
Ishtiaq's two brothers, Ilyas and Idrees, both agriculture students in Peshawar, visited him at the hospital. The two men later died. One of the men tested positive for the H5N1 influenza strain. The other case is yet to be confirmed.
The Center for Disease Control and Prevention in Atlanta was notified by Nassau county authorities in New York that one person, recently returned from Pakistan on Dec. 5, had contact with the bird flu victims. "The contact tested negative for the H5N1 virus and this was confirmed by the CDC," stated a CDC spokesman. The contact was placed under medical observation and released.
This is the first outbreak of the H5N1 bird flu strain among humans in Pakistan. But since 2006, the disease has been found among poultry along the North-West Frontier Province's 'poultry-belt,' and wild poultry infections have even been found in the Islamabad Capital Territory.
Three World Health Organization experts were dispatched to Peshawar early this week. They visited a hospital in Peshawar that treated most of the eight H5N1 cases.
In a press statement, WHO stated it will be "providing technical support to the [Pakistani Minister of Health] in epidemiological investigations, reviewing the surveillance, prevention, and control measures that have been implemented and carrying out viral sequencing of avian and human isolates."
U.S. Naval Medical Research Unit No.3 also arrived in Pakistan from Cairo Thursday. The unit is expected to retest samples taken by Pakistani government officials.
Avian influenza is an infection caused by naturally-occurring viruses that reside in the intestines of birds. Weaker strains cause mild symptoms in birds while stronger strains can result in organ failures and a mortality rate of 90-100 percent within 48 hours.
Several strains of avian flu have crossed the human-bird species barrier. Because human immune systems are not accustomed to fighting the disease, the human population has little or no immunities against avian flu.
Of all the avian strains that have jumped the species barrier to humans, Influenza A H5N1 is the most deadly. The disease remains rare. Only limited human-to-human spread of the disease has occurred following close and prolonged contact.
However, health officials fear that genetic mutations in the H5N1 virus may give avian flu the ability to spread as quickly as the common cold. The influenza epidemic of 1918-1919, caused by the H1N1 virus also found in pigs, killed between 20 million and 40 million people worldwide.
Since 2003, of the 341 cases of H5N1 strain of bird flu, 210 cases have proved fatal. Despite the high fatality rate of H5N1, Pakistan's Ministry of Health spokesman Orya Maqbool Jan Abbasi assured the global health community that there was no threat of an epidemic or pandemic.
The Pakistani Health Ministry is sending pamphlets and radio messages to the North-West Frontier Province to implore villages and farms to follow health guidelines to stop further avian flu outbreaks.