Friday, January 07, 2005

Bird flu: red flags in the east

Hard on the heels of the Thai work suggesting many missed cases of influenza A(H5N1) in that country (see post here) comes a notice in the Eurosurveillance Weekly (via ProMed) about another strain of avian influenza A(H7N7). That strain was responsible for a reported 86 infections in poultry workers and 3 cases with no poultry contact in the Netherlands in the spring of 2003. Most infections produced only a mild conjunctivitis, but an infected veterinarian in close contact with the animals died of respiratory distress syndrome.

Now a follow-up investigation using questionnaires and serology of 400 poultry farmers, their families, another 900 people involved in the mass culling operation and 62 household contacts of 25 persons with H7N7 infection has confirmed what the Thai and Japanese studies of H5N1 have revealed, that there are many more infections than officially reported.

A modified blood test showed that 50% of those in contact with sick birds had H7 antibodies, leading to an estimate of 1000 to 2000 avian virus infected individuals. The human to human infection rate was an extremely high 59%:
This suggests that the population at risk for avian influenza was not limited to those with direct contact to infected poultry, and that person-to-person transmission may have occurred on a large scale.


A review of the outbreak and control efforts in the Netherlands highlights important lessons for preparedness: while separate systems are in place to signal and control animal diseases and human diseases, an outbreak of a zoonotic disease illustrates the importance of coordination between the 2. In the Netherlands, the people infected came from a wide geographic region and included foreign poultry workers. While the movement of animals was restricted, these people were out of the reach of the public health authorities while infectious and shedding the virus.

Although the disease in humans is more severe for A/H5N1, both avian influenza outbreaks illustrate that crossing the species barrier is less rare than previously recognised, that avian influenza virus adaptation occurs rapidly, and that if such jumps between species occur, human behaviour in the broad sense may accelerate dissemination.
Thus the Thai, Japanese and now Dutch studies show that human infection with avian influenza A virus may be both more common and more easily acquired than previously thought.

Meanwhile, the Viet Namese are reporting yet another suspected case of H5N1 infection, their third in a week. This comes in a setting of a full scale effort to bring under control a major outbreak of the virus amongst poultry in the country. According to The People's Daily (China):
. . . since December last year, the relapse of bird flu [in Viet Nam] has been seen in 25 communes in11 localities . . . leading to the forced culling of some 28,700 fowls, mainly ducks and chickens.

Fearing that severe outbreaks of bird flu will happen during the Lunar New Year Festival ( early February), when cold weather favors the development of viruses and a larger number of fowls are transported and traded, local veterinary forces are making closer surveillance on areas formerly hit by bird flu, covering poultry farms, markets or slaughterhouses.

[The Viet Namese] attach great importance to monitoring the transport and trade. The country's veterinarian forces nationwide, early this week, resumed a 24-hour operation to monitor transport and trade, which was applied in early 2004 when bird flu was at peak period in the country. Veterinarian cadres are to go deep into wards and hamlets to monitor poultry flocks, so that Vietnam's Department of Animal Health can have an updated report on new outbreaks and the number of dead and culled fowls everyday.

Many cities and provinces nationwide have just established hotlines, in a move to get latest news on bird flu situation. The southern city of Can Tho, which finds that nearly half of samples from ducks raised in the locality are tested positive to the bird flu virus strain of H5, has publicized such three phone numbers.

Under the department's recent instruction, transport of poultry with large volume must get approval from local veterinary agencies,and more quarantine checkpoints along roads must be set up leading to centers of cities and provinces. The capital city of Hanoi has just established four checkpoints, raising the total to 12.

Some localities like Ho Chi Minh City even imposed stricter rules on the transport. Fowls and their eggs which are not quarantined by the agencies or carried to the city by simple means of transport, such as bicycles and motorbikes, will be confiscated and then destroyed. Besides, the city assigns veterinary cadres to be present at all of its 59 slaughterhouses. The cadres are to inspect fowls before they are slaughtered and then packed into plastic bags.

To encourage residents to actively detect new outbreaks and prevent raisers from not selling their sick chickens, some provinces have offered cash rewards to informers and raised level of financial assistance to farmers. The northern province of Ha Tay presents 50,000-100,000 Vietnamese dong (VND) (3.2-6.4 US dollars) to each informer, while the southern province of Tien Giang gives raisers 15,000 VND (nearly one dollar) for each fowl culled, instead of 5,000 VND (0.3 dollars) as it did previously.

In addition to professional measures, Vietnam is intensifying propaganda via mass media. Local residents are urged not to throw dead fowls away, not to have direct contact with poultry, and keepfit. People with symptoms of high temperature, running nose, cough and exhaustion are advised to go to healthcare facilities as soon as possible.
So the Viet Namese are taking this pretty seriously, as are the Chinese. Warning flags are flying all over the place according to knowledgeable public health experts. So why are you reading about this here and not seeing it on the evening news, the American print press or from American public health officials?

Why indeed?