10,000 ducks in Guangdong Province in the south of China have died of bird flu and 100,000 more culled in an attempt to stop the spread of the disease. Massive bird flu outbreaks are not exactly a novelty these days but the Chinese incident is noteworthy because it is now reported the ducks were in vaccinated flocks:
According to Guangdong Animal Epidemic Prevention Center director Yu Yedong, the 9,800 ducks that died at Sixian village had been vaccinated. But he added the first vaccination could only be 65 percent effective, while a second shot would have made it 90 percent.He believed the birds were infected after the first shot. The deaths led to a mass culling of 32,600 ducks on Friday in an attempt to contain the outbreak.
Health workers have been spraying disinfectant on every passing vehicle and duck farms around the village. (The Standard [Hong Kong])
Vaccinating poultry has been touted as both the answer to the bird flu problem and a dangerous practice because it masks the fact of infection in poultry that can still become infected and shed virus. There has thus always been a question as to whether it is effective and this report suggests it isn't even working to keep the birds asymptomatic (which from the public health perspective is actually a good thing because it allows us to become aware the flock is harboring the virus). Whether this is the result of a change in the virus that allows it to escape the protective effects of the vaccine or whether the vaccine was never very effective in the first place or requires multiple applications or whether the vaccination program itself is at fault with records showing birds as being properly vaccinaed when they weren't or some combination of these factors or something entirely different we don't know. But so far no one strategy has stopped this virus.
Both H5N1 and SARS started in Guangdong, which is the part of the mainland closest to Hong Kong. China is the world's largest poultry producer and has officially reported 25 human cases and 16 deaths. If you think that's all there has really been, I have a used car to sell you. and some prime real-estate in Florida. Oh, yeah. The bridge in New York. I say this because disease surveillance and detection in China is manifestly inadequate to have a realistic chance of full ascertainment of cases. Given China's past record on disease reporting and the fact they are hosting the 2008 Summer Olympics in Beijing, however, I am not discarding the idea there has been some cover-up of cases. I just don't know, but it is a suspicion the Chinese authorities have brought on themselves.
The virus, like a clever computer hacker, finds ways to get around our firewalls. Let's hope we don't have to reboot the human species.
Medicine & Health
Comments
If your know something about vaccination the you know you need 2 shots to have the right titre in order to give an immune respons. In the original message they state very clear the ducks had only one shot. The second should be given after a week and then it takes another 3 weeks until they are fully protected.
If children were not vaccinated against diseases there would be masses of epidemics going around. The same for vaccinating cattle against the most harmfull pests. In Europe they stopped vaccinating in 1993 which led to numerous outbreaks and millions of animals killed.
Questioning the effectiveness of vaccination to fight diseases is therefore an old fashioned way of thinking. Unless you feel your Church is against it. If so, then accept the fact you and your children become ill if you're not vaccinated. Same for animal diseases.
I wonder why there are still voices that are against vaccination. So what if the virus sheds, the virus will die when there are no animals left, bird flu is a bird disease!, to infect. Seems commercial industry has long arms to influence common sense.
Posted by: Sigrid van Dort | September 18, 2007 9:12 AM
Sigrid: Please read the post more carefully. There is no indication we don't believe in vaccination in general (for all diseases and all species). We raised the same question others have raised about vaccinating poultry for H5N1: is it effective.
Posted by: revere | September 18, 2007 9:52 AM
Vaccination, in general, has undoubtedly saved countless animal and human lives. When the vaccine is developed, produced and administered effectively that is.
When one piece of the equation is missing at best it doesn't protect the individual. At worst it is a disaster.
I hope I'm wrong but what's going on in China sounds like a disaster to me, regardless of the reason for its occurence.
Revere, I'd like to say thanks to you and your colleagues for making issues such as this understandable and accessible to the average person. I comment very rarely but read often.
Posted by: MaMa | September 18, 2007 1:01 PM
There have been many reports that the animal vaccines have been only partially effective--certainly true for humans. Question is, can we frame partially effective vaccination in the same way that we combat the virus by using low propylactic or inadequate dosages of antivirals. Does this put evolution pressure on the virus to evolve? I don't recall many studies for other diseases, but maybe someone can enlighten me.
Posted by: Marissa | September 19, 2007 9:19 AM
Revere, I dimly recall there being some suspicion about Chinese vaccines, in particular, being ineffective... I believe this was during the Egypt outbreaks last winter. Didn't they use Chinese vaccine there, but then switch to a different vaccine after their outbreaks?
Posted by: caia | September 20, 2007 12:50 PM
That's like going to Dracula for a blood transfusion.
Posted by: Tom DVM | September 20, 2007 6:42 PM