An autopsy performed on a pregnant Chinese woman who died from H5N1 avian flu infection showed the virus passed to the fetus, Chinese researchers report in the journal The Lancet.
The researchers, from several institutes and universities in Beijing, found the "transplacental transmission" of the H5N1 virus interesting, since the virus doesn't normally affect the fetus with common flu infections.
The researchers found the fetus' lungs contained many infected cells, but didn't create the severe damage seen in the lungs of the 24-year-old pregnant woman.
The scientists suggest the lack of damage was likely due to the fact that the immune system of the fetus was not developed and therefore its body didn't mount an attack on the virus and didn't release chemicals -- cytokines and chemokines -- that may worsen lung damage.
The report is the first to contain autopsy data for either a pregnant woman or a fetus.
It's also the first to come out of the Infectious Disease Center at Peking University in Beijing, which was created after the epidemic of SARS and that is now intensely studying the H5N1 strain of avian flu.
"The work helps us to understand H5N1's high fatality rate, as well as serving as model for global collaboration in the field of emerging infectious diseases," said Dr. Ian Lipkin of Columbia University in New York, who directed the study.
The researchers also performed an autopsy on a 35-year-old man and found genetic material from the virus in the man's lungs, as expected. But they also found the material in the man's brain, intestines, and in immune system cells in the blood and the liver.
The damage in the lungs was particularly severe, lending weight to the theory of a "cytokine storm" -- the idea that the immune system goes into overdrive against the virus in some cases, and sends out a swarm of chemicals that end up killing the patient.
The H5N1 strain of bird flu has killed 60 per cent of the humans it has infected. To date, all pregnant women known to have been infected -- about a half-dozen -- have either died or had a spontaneous abortion.
Although at least 200 people have died from H5N1, there has been a pitiful lack of autopsy data available for scientists to study. Most of the deaths have occurred in countries where autopsies are not performed for cultural reasons.
