Bird flu: soup's still on

Bird flu news tends to be episodic. For long stretches there seems to be little news (unless you deliberately go looking for it; then you find it). Then there are these little spurts as bird flu pops up here and there in the news. Human cases in places where they haven't been for a while tend to be more noticeable. Or suspicion there are cases where they haven't been before. So we have Malaysia quarantines five with suspected bird flu (possible new country for human cases; but suspect cases of febrile illness around poultry outbreaks often turn out "negative," either because they are one of the many other common illnesses or because they are false negatives; if they turn out to be bird flu, I wouldn't be surprised; if they turn out not to be, I wouldn't be surprised); Vietnam reports 2 more human cases of bird flu (more new human cases in a country touted as having successfully controlled bird flu in poultry and in people); Egyptian girl diagnosed with bird flu (another case, the second in two weeks, in the country outside of Asia with the most cases [36], half of them in 2007).

And of course -- of course -- Indonesia:

An Indonesian expert from the Research Center for Biotechnology of Gadjah Mada University, Widya Asmara, said that there had been indication that the viruses had geographically changed.

"It is urgent to conduct more researches to prove the change," he told Xinhua.

If the change is significant, it will be necessary to develop anew strain of vaccine, he added.

"There are some indications that some strains of the viruses have changed in some regions," he said.

Another Indonesian expert, Ngurah Mahabarata, said that the highly pathogenic H5N1 virus so far had spread before it could control properly.

"When the virus has a chance to infect poultry, it has a chance to develop and at the same time it changes its structure," he said.

John Weaver, from the avian influenza control program of the United Nations in Indonesia warned of the risk when the virus changes.

"We have to be aware that there is always a risk that the field virus is becoming more different," he said. (XinhuaNet)

Indonesia and other countries are hoping poultry vaccination will stop the disease without mass culling. It might. But it might also just provide enough protection that the birds don't get sick but still become asymptomatically infected, still shedding virus that could infect people. Asymptomatic infection of poultry has been reported from China and now the Indonesians are also saying they have found it:

Indonesia has found traces of H5N1 bird flu in apparently healthy-looking poultry, making it tougher to detect the disease in the country hardest hit by the virus, officials said on Monday.

Sick or dead chickens are used as a sign of H5N1 infection, but the appearance of "asymptomatic" chickens means humans could become more easily infected with bird flu. Indonesia has the world's highest death toll from the disease, killing 79 people.

"The poultry death rate is not so high, but there is a trend that chicken or poultry are infected by the virus but they don't die. So, the H5N1 virus is not fatal to poultry," Musny Suatmodjo, director of animal health at the agriculture ministry, told a news conference. (Reuters)

Presence of sick or dead poultry is a signal to clinicians they should do diagnostic work-ups for H5N1 infection in people with flu-like symptoms nearby. If some people are becoming infected from shedding but asymptomatic poultry, it could mean cases are being missed because of the absence of a sufficient diagnostic index of suspicion.

There is as yet no evidence bird flu is boiling over in the epidemiologic cauldron that is the millions of infected birds living cheek by jowl with millions of people. But for sure it isn't fading away. It is bubbling away.