Combating bird flu in Asia

Jai P. NARAIN

As long as poultry remains an intrinsic part of Asian households, bird flu will be a threat. It is important to study the lessons learnt and adopt the best practices.

The current situation of avian influenza or bird flu is quite unprecedented and alarming. It raises particular concern regarding the potential threat of an influenza pandemic which many medical historians believe is imminent.

The devastating effects of the 1919 pandemic and the 40 million lives it claimed are stark reminders of what could be looming on our doorsteps. The last century saw three pandemics, the last one occurring in 1968.

Looking back, we find that an outbreak caused by the highly pathogenic H5N1 strain of the avian influenza virus was reported in Scotland in the 1950s; human cases occurred for the first time in Hong Kong in 1996.

The current outbreak which began in China in late 2003 is unparalleled in terms of the number of countries affected. More than 65 countries across Asia, Europe, Africa, and the Middle East have reported infection in poultry or wild birds.

The spread across continents can be partly attributed to migratory birds, but recent events have pointed to the movement of live bird and poultry products. Human cases have been reported from 14 countries, seven of which are in Asia.

The situation remains highly dynamic with recent outbreaks in poultry in Bangladesh, China, India, Indonesia, Myanmar, Thailand, and Vietnam.

The concern is not focused on bird flu per se, but on the potential risk of it igniting an influenza pandemic.

This H5N1 virus has the tendency and the capacity to change through re-assortment through mixing with other circulating seasonal influenza virus strains.

In fact, influenza can be categorised into three broad types from the public health risk perspective: seasonal influenza or common flu; avian influenza, in particular H5N1 among birds or poultry; and finally, pandemic influenza.

We have no idea if, and when, the pandemic will occur and whether it will be caused by the currently circulating H5N1 virus or another virus.

Bird flu now appears to be firmly entrenched in much of Asia. Moreover, there is a close interface between animals and humans as well as humans who share a common dwelling with animals including poultry, putting them at risk.

Bird flu primarily lurks in the animal sector in most countries, especially among backyard poultry.

Transmission from poultry to humans is uncommon but it has occurred among adults and children exposed to sick or dying chicken. Relatively few deaths of human infection have occurred to date but mortality at 61 per cent worldwide is very high.

There are a few examples of human cases occurring in clusters. In 2004, Thailand reported a case when a mother fell ill after providing care to her sick daughter in hospital; she had otherwise no exposure to sick or dying chicken.

Then, in 2006, several members of one family developed avian influenza in Karo, Indonesia after being exposed to a sick family member at home. There have been a few clusters reported in Vietnam too.

Although transmission of avian influenza from human to human is rare, preparedness is pivotal in view of the dynamic nature of the situation. At least two of the three pandemics that occurred in the last century originated from Asia and this is a sobering thought. Will the next pandemic virus also emerge from Asia ? It is anybody’s guess.

Control measures and precautions

A prerequisite for preventing the pandemic is containing the virus at the source itself - in this case, in the animal sector. The most important control measures include practising bio-security, culling of poultry combined with quick and adequate compensation to farmers, and vaccination of poultry as an adjunct measure.

The control measures in the human sector include prevention of exposure to infected poultry and reducing case fatality rates.

The precautions that people must take in an outbreak area are fairly straightforward: knowing how to steer clear of getting infected by avoiding exposure to and contact with sick and dying chicken, and not de-feathering poultry at home.

In the event that one develops an influenza-like illness, prompt consultation at a health facility is recommended with suitable anti-virals taken within 48 hours. Consuming chicken is safe as long as it is cooked thoroughly at a high temperature since the virus cannot survive at boiling temperature.Lessons learnt

Avian influenza outbreaks have brought to light several dimensions. The cultural and economic spin-offs from a traditional way of life, especially in Asia, have been brought under the spotlight.

The political commitment to inter-sectoral collaboration, particularly between the agriculture and health sectors, has led to rapid and successful containment of the outbreaks in many countries including India.

The high case fatality rates documented in the outbreaks, especially in Indonesia (nearly 85 per cent recently), is of immense concern. In order to understand why, and what can be done to reduce this, research is a priority.

The communication messages needed to alter risk behaviour and improve case management to reduce death from avian influenza pose key challenges. To prevent avian influenza and to rapidly contain its spread, the World Health Organisation is urging all countries to get their national preparedness plans ready and tested in the event of an emergency.

Table-top exercises and mock simulation drills are being suggested to help fine-tune the response mechanism. The rapid containment strategies include early and strategic use of anti-virals and public health measures such as social distancing, school closure, restricting gatherings and cough etiquette.

Planning in advance remains critical and “failing to plan is to plan to fail.” In the event of an influenza pandemic, one needs to be prepared for the worst.

The attempt should be to try and minimise the impact. It could affect up to 15 per cent of the population, leading to an enormous number of people getting sick within a short period of time and requiring treatment and health care, thereby further stretching the already fragile health care infrastructure.

Strategic actions to cope with and mitigate the impact would consist of implementing a health and essential services contingency plan capable for dealing with a massive surge in demand for services.

Public health measures

Simple public health measures such as washing hands, maintaining cough etiquette and banning public gatherings may be our most important tools to limit opportunities for human-to-human spread. Vaccines and anti-viral treatment are unlikely to be available for all those who need it.

The use of law enforcers in ensuring law and order and preventing the possibility of rioting or social disturbances are part of the emergency plan.

While vaccination is an ideal strategy for prevention during a pandemic, vaccine development has to catch up with demand. The development of a pre-pandemic vaccine is in progress, with Phase 2 trials ongoing. Early results suggest that the vaccines are safe and relatively immunogenic, and may offer cross-protection.

Long-term strategies to combat a pandemic include transfer of technology and capacity building to improve production capability both in the developed and developing countries.

WHO is supporting projects in six countries, of which four are in Asia - India, Indonesia, Thailand and Vietnam. Equitable access to vaccines and anti-viral treatment by the developing world, however, remains a major global issue.

Finally, as long as poultry remains an intrinsic part of Asian households, bird flu will continue to emerge. Hence, it is critical to take stock of the lessons learnt and put in place the best practices. Only then will we be able to tame, if not overcome, this virus.