Almost all stories in the news about H5N1 (bird flu) have some obligatory line in them, "It is believed that all or almost all human cases come from contact with infected poultry." This is like a mantra of many public health officials and I suspect some reporters have the requisite disclaimer as a cut and paste text they mechanically insert into their stories. But it isn't true. There are an awful lot of human cases for which no poultry source has ever been located and we have yet another example in the latest Indonesia cases:
The city's husbandry, fishery and maritime agency said Friday it did not find the H5N1 virus in any fowls found in the neighborhood of the latest suspected bird flu victims.Agency head Edy Setiarto said samples taken from poultry in the Gandaria Utara, South Jakarta, showed negative results.
"We took the samples Thursday and had them examined in our lab in Ragunan, South Jakarta, after scanning an area in the subdistrict with a radius of 100 meters," he said.
"We found out later that day the tests were negative," he said. (Jakarta Post)
This case is mysterious in other ways, too. It was originally reported that the teenage girl's 15 year old brother was also a bird flu victim, but the story now goes that the brother died of typhoid fever 10 days before his sister. Had it been bird flu this would have been looked on as a likely person to person transmission. It seems a bit convenient -- but still possible, I suppose -- that the brother died of another fatal infectious disease within exactly one incubation period of his sister. Since it sounds like the brother died before the diagnosis of bird flu was suspected and the diagnosis is based on an unnamed blood test rather than PCR you have to wonder. Of even more interest is the report that a family member of the two, a 24 year old, is being treated at another hospital with bird flu like symptoms.
Which again raises the question of where the latest confirmed victim acquired the infection. Is there another reservoir besides birds? How about another person? The Indonesian authorities are said to be conducting blood tests on contacts of the victim but we don't know what kind of tests, what their timing is, what follow-up there will be, or, of course, what the results are.
As we have said before it is time for more systematic, widespread and intensive tests to estimate the extent of infection in the natural world with H5N1 virus. We and others have called for seroprevalence studies in exposed populations to see if there is more covert infection than we know about. There is now word from Vietnam that Vietnamese and American scientists will be launching such a study in the fall:
As of October 2008, American experts will conduct wide-scale research in Vietnam on antibodies countering H5N1 that may exist in Vietnamese people's bodies.
The research, which will be carried out by experts of the US National Health Institute, will be conducted through a collection of blood samples from man, poultry, water samples, and social surveys on people's awareness of the disease and access to poultry.
According to Dr. Polly R. Sager of the US National Health Institute, it is supposed that antibodies may appear in the bodies of people who are infected with less toxic H5N1 virus types. If this supposition is verified, the people who have antibodies may be partly protected against stronger H5N1 virus types.
A study involving 850 families in the three provinces of Ha Tay in the north, Thua Thien-Hue in the central region and Tien Giang in the south shows that around 12,000 people may be exposed to bird flu.
According to Dr. Sager, bird flu in Vietnam is different from many other countries because in Vietnam, families breed poultry and cattle in the same area. Each animal has their own virus types so it is highly possible to have a combination of flu viruses from different kinds of animals. (Vietnam Net)
So this is good. But we also need some systematic surveys of other wildlife, including rodents, shrews, various primates and domestic animals and livestock.
The virus may be hiding in plain sight. We should be looking for it. Now.
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You are correct in being suspicious about her brother's diagnosis of 'typhoid'. I frequently work in public health in Jakarta and my coworkers laugh when they hear a diagnosis of typhoid as it is commonly overdiagnosed without laboratory confirmation. One of my coworkers there took just three days off work when he had 'typhoid' last month.
Sounds like human to human avian flu transmission to me ...
It may of course be that the Indonesian tests on the local poultry:
a) produced false negatives
b) were positive, but have been reported by the officials as negative
The fact that this investigation was performed by regional level bureaucrats lends me to believe that scenario B might be the most accurate. There are strong political incentives for local administrators to hide positive bird flu results, much more so than exist at the national level.
That is not to say, of course, that more widespread surveillance of wildlife is not of benefit, nor that P2P has not occurred here - just that there are other, more mundane, possibilities which need to be considered.
Or Rieux, there is endemic H5N1 in an increasingly outspoken against government country and the possibility of democracy in front of a pandemic might be getting ready to break out.
Andrew J. was there for many years and has posted off and on for years about the medical situation there. I dont think they will acknowledge it unless it goes to full epidemic status first. By then it will be too late.
We sit, we wait, we watch....
Cheers:*) Big Ears Revere,
I love the way you wind ironic sentiment into your critical questioning of a "surveillance system" which seemingly has yet to grasp the fundamental nature of a cross-species pathogen -- this is a terribly slutty virus which gets into bed with many more species than the "journo" party-line mantra of us humans and wild and domestic birds!
I agree with your post, revere.
I'm not sure if you are aware of this, but last year I discovered that two unrelated individuals were infected with H5N1 viruses with identical sequences in all 8 genomic segments. IMO, this can only mean that both were infected with the same virus. One individual was from Banten province and the other from South Jakarta (in Indonesia). Although they live in the same general region, it seems unlikely that they were infected by the same chicken. My guess is that they were infected by the same mammal, possibly another human being.
You can read more here, if you are interested:
1 Sequences from Unrelated Individuals - Evidence of a Geographical Cluster.
http://tinyurl.com/2y7bha
Fascinating and understandable, as ever. I'd be interested to know what you think of Prepandrix and the underlying assumptions about the transmission of the virus?
Yay for the Vietnam study! If there's an antibody present that could lead to us having a protective vaccine, even if it's only going to diminish the effects, I will get my second ever flu shot.
hiding in plain sight:
experimental studies have demonstrated that vaccinated poultry can be infected with H5N1, and transmit the disease to other vaccinated and unvaccinated birds.
Cryptic (i.e., asymptomatic) infections with H5N1 may also occur in poultry infected with the ubiquitous low-pathogenic H9N2 virus.
Transmission is occurring among people, yes, but just because there are no poultry dying doesn't mean the virus is not circulating locally in vaccinated birds ....
elephantman: You are correct and we have posted on this repeatedly (see, for example here). Unfortunately one side effect of vaccination is that you can no longer do serology to see if there is infection. You'd have to try to isolate the virus or do PCR to see if the birds were infected.