April 7, 2008 -- A Chinese father, 52, barely survived bird flu he caught from his son, 24, who died.
The December 2007 cases are only the second time scientists have demonstrated probable human-to-human transmission of the H5N1 bird flu virus. But a fourth of the 378 known human cases of H5N1 bird flu have occurred in two or more "epidemiologically linked" clusters of people -- usually other family members.
Of course, family members may share exposure to sick poultry. This is by far the main way people get the virus. That's because H5N1 is still a bird virus, and has not adapted to human hosts.
However, the virus may well adapt to individuals unlucky enough to catch it from humans. Family members, are genetically similar. This means people may be at higher risk of catching the deadly virus from a relative than from someone to whom they are not related, suggest Nguyen Tran Hien, MD, MPH, PhD, of Vietnam's National Institute of Hygiene and Epidemiology, and colleagues in an editorial in the April 8 online issue of The Lancet.
"All family contacts of a patient with probable or confirmed H5N1 should be given [preventive treatment with flu drugs] and placed under surveillance," Nguyen and colleagues write. "Personal protection and advice must be extended to the family members and health workers visiting and looking after patients in the hospital."
The World Health Organization is currently following a cluster of human cases of H5N1 bird flu in Peshawar, Pakistan. Four members of this family fell ill -- three with confirmed bird flu and one with "probable" bird flu. Two died and two recovered fully.
"Laboratory tests results support ... the final risk assessment that suggested limited human-to-human transmission likely occurred among some of the family members," the WHO report states. "This outbreak did not extend into the community, and appropriate steps were taken to reduce future risks of human infections."
Father Gets Bird Flu from Son
Details on the sad case of the Chinese father and son come from Hua Wang, MD, of the Jiangsu Provincial Center for Disease Control and Prevention, and colleagues, also in the April issue of Lancet.
The son, a salesman, lived in an urban area with his mother. He had not been feeling well since August 2007, but on Nov. 24 he came down with a fever. He was given antibiotics and sent home. Three days later he was hospitalized with pneumonia.
Blood cultures on Nov. 28 detected a Salmonella infection (probably the cause of his earlier illness) and he was treated with antibiotics. Five days after entering the hospital, he died -- the same day a sample of lung fluid detected infection with H5N1 bird flu.
Meanwhile, the young man's father had been helping to care for him in the hospital. Even though he performed intimate care -- changing the son's diarrhea-soiled clothing and bed sheets, feeding him, and cleaning out a spittoon used for sputum -- the father was not given protective gear until the son's H5N1 infection was detected.
Two days after his son died, the father developed a fever, chills, and cough. He took a dose of Tamiflu that had been provided. The next morning, he was hospitalized. Despite treatment with flu drugs, he got worse, requiring positive-pressure ventilation.
Four days later, he received two transfusions of plasma from a woman who had received two doses of an experimental H5N1 vaccine in an early-stage clinical trial. That night, the father's fever resolved. He left the hospital 22 days after admission.
Both the father and son were infected with virtually identical H5N1 strains. Six days before his illness, the son visited a market where poultry were slaughtered. Even though he did not visit the poultry booths, the market appears to be his only possible contact with infected poultry -- although nobody else appears to have been infected and there was no known H5N1 outbreak among poultry in the region.
The father, too, had been to a market that slaughtered poultry as recently as eight days before his illness, but given the incubation period for bird flu -- three to six days -- Hua and colleagues feel the father's exposure to the son was a much more likely source of infection.
One hundred other people were exposed to the son, including his girlfriend and a doctor who came down with a cough and fever. But tests showed none of these people had become infected.
"H5N1 clusters require urgent investigation because of the possibility that a change in the epidemiology of H5N1 cases could indicate that H5N1 viruses have acquired the ability to spread more easily among people," Hua and colleagues warn.
The World Health Organization has officially confirmed 378 human cases of bird flu, with 238 deaths, in 14 countries.