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H5N1 2004 in Laos - Veterinarian's Experience

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  • H5N1 2004 in Laos - Veterinarian's Experience

    The Lancet Infectious Diseases 2005; 5:143-145
    A veterinarian's experience of the spring 2004 avian influenza outbreak in Laos Dr Clara J Witt (US Public Health Service Commissioned Corps veterinarian and Deputy Director for Antimicrobial Resistance, Zoonotic, and Vectorborne Disease Surveillance) a and Joseph L Malone (US Navy Medical Corps, and Director) b

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    Since it was first reported in December 2003, the outbreak of avian influenza A/H5N1 has spread to at least nine countries in Asia, affected multiple species of animals, and caused at least 42 human deaths. The magnitude and extent of this zoonotic outbreak are unprecedented, continue to grow, and threaten the start of a global human influenza pandemic. Control of the H5N1 outbreak has required the implementation of integrated human and veterinary health surveillance and response efforts. These efforts have also necessitated an unprecedented level of bilateral and multilateral international communication and cooperation. This report describes the contribution of one public-health veterinarian to the H5N1 outbreak response effort in Laos, and emphasises the value of multidisciplinary approaches to addressing this and future emerging infectious disease outbreaks.
    As of Feb 2, 2005, the avian influenza A/H5N1 outbreak has directly affected nine countries (Cambodia, China, Japan, Indonesia, Malaysia, Korea, Laos, Thailand, and Vietnam), and has resulted in 55 known human cases and at least 42 deaths. Although an imprecise indicator of severity because of inherent difficulties in identifying and reporting cases in affected countries, this 76% case fatality rate shows the human health threat posed by H5N1. It has the potential to cause an overwhelming, worldwide influenza pandemic. In addition to the human health threat, the H5N1 outbreak has resulted in the death and culling of well over 100 million sick or at-risk poultry in Asia, having a devastating economic impact on the poultry industry in affected countries.
    As public-health professionals, veterinarians contribute expertise in the identification of affected and exposed poultry, and they promote and implement safe and effective methods for humane handling and culling of affected animals. As integrators between agricultural and public-health interests, veterinarians not only promote the use of biosecurity measures for the protection of unaffected flocks, they advocate for, teach the principles of, and show how to achieve biosecurity measures for the protection of people exposed to poultry under a variety of husbandry and environmental conditions (figure 1). They provide guidance on safe food handling, techniques for avoiding H5N1 infection from potentially contaminated aerosols, droplets, or debris, and the detection of potential human cases through the use of bird-exposure questions during patient history taking. Public-health veterinarians encourage the collaboration and cooperation necessary between ministries of agriculture and health to effectively curb the H5N1 outbreak and mitigate its social, economic, and health impact.

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    Figure 1. Training agriculture workers in the use of personal protection equipment

    Among the countries reporting H5N1 poultry infection was Laos, one of the poorest countries in the world in terms of gross national product. Laos faces enormous challenges in providing basic services, roads, schools, telecommunications, and health care to much of the country outside its main urban centres because of its mountainous, densely forested terrain, and the isolated lifestyles of its ethnically and linguistically diverse people. This situation makes it difficult for Laos to handle an H5N1 outbreak (figure 2).

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    Figure 2. In Laos most rural housing is isolated and without running water or electricity

    As a US Public Health Service (USPHS) veterinarian experienced in public health, I (CJW) consulted for the WHO in Laos between February and April 2004 to assist the Ministries of Health, and of Agriculture and Forestry to assess Laos' H5N1 risk, and encouraged the implementation of measures for detecting, reporting, controlling, and preventing H5N1 infection in Laotian people and poultry.
    Before I arrived, Laos had reported H5N1 in poultry in the capital, Vientiane, and in Savannakhet and Champasak provinces in the south. These reports led the central and provincial governments to establish interagency task forces to prohibit the sale or transport of birds from affected areas, and heighten existing human and poultry disease surveillance activities. Identified affected flocks had been culled already. Fortunately, no provinces in Laos were reporting human H5N1 cases. From the perspective of the national authorities, the outbreak was under control. Therefore, I focused on travelling to provinces and districts reporting no H5N1 poultry or human activity but which were considered high risk because of their proximity to known affected areas in China, Vietnam, or Thailand. These were areas with recognised difficulties in implementing and maintaining both veterinary and human disease surveillance activities. While travelling, I talked with many veterinary and public-health officials, farmers, and ordinary people, and learned their views on this dangerous outbreak.
    My first trip was to the declared positive provinces of Savannakhet and Champasak, where quick and effective bird culling and farm clean-up practices had been initiated by the farmers. These people were the new middle-class of Laos, knowledgeable entrepreneurs who invested in commercial poultry farming to improve their personal lives as well as the country's fragile economy. Many had imported their poultry from Thailand, and were alarmed as they followed the outbreak on television. They understood the agricultural need to report and cull affected flocks, but neither they nor the provincial authorities were aware of the inter-species transmissibility of H5N1 and the threat to human health. They were not practising measures to prevent human exposure and were not monitoring exposed farm workers for infection.
    I could not identify the definitive source of the reported H5N1 infections. I did speculate that the virus was brought onto the farms by chickens imported from Thailand, but I found no specific evidence to substantiate this hypothesis. During my interviews with affected farmers, however, one story kept surfacing. During January and February 2004, farmers had noticed that their neighbours' free-ranging chickens had died in large numbers. This was never reported to authorities because, as the farmers told me, these birds always got sick and died during the winter months, usually from Newcastle disease or fowl cholera, the two main poultry diseases in Laos. These deaths were not worth reporting because the free-ranging birds had no economic value. It was only commercial poultry farmers with thousands of birds who reported poultry morbidity and mortality to government officials. All farms visited practised suboptimal biosecurity measures for protecting their flocks from exposure to wild and free-ranging birds.
    In other provinces I was told similar stories. At Oudomxay, in the north, a cross-roads town with links to Vietnam and China, I discussed H5N1 with the veterinary officials and administrators at the provincial hospital. I lectured on H5N1 and why it was a public-health threat. People were very polite, but did not seem that interested until I showed them US Department of Agriculture pictures of affected chickens. This use of visual aids paid off. I was taken to a small farm and shown chickens that had suddenly become ill. The birds had signs and symptoms compatible with avian influenza (figure 3). As the veterinarians had never seen it before, they did not want to make a presumptive diagnosis of a disease that did not exist in their province. As we discussed possible differential diagnoses, their reluctance turned into satisfaction that they had the training and capability to identify a new disease, and that they were able to initiate diagnostic and control measures to meet this new situation. I learned that Laotians were very keen to practice good veterinary medicine and public health, but as a verbal explanation from a foreigner, H5N1 meant little to them. Pictures allowed them to appreciate that H5N1 could, and did, affect them. As a result, I developed a picture booklet explaining what H5N1 was, how it could affect birds and people in Laos, and what measures Laotians could take to prevent, diagnose, and control H5N1 in poultry and human beings. The booklet became the primary technique for training and encouragement in other provinces visited.

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    Figure 3. Poultry with typical clinical signs compatible with H5N1 infection including erythema and swelling of wattles and comb (chicken) and neurological signs (duck)

    In Da Cheung, a remote district along the old Ho Chi Minh trail near Vietnam, the booklet represented the first information they had seen on the H5N1 outbreak. Near Da Cheung is the village of Bakmai, a village with nine households. Bakmai had lost all its chickens in January, but as the residents did not speak Lao, even with local interpreters, I could not get a good history of what had occurred there. However, it was evident that in a district lacking electricity, telecommunications, and year-round roads, accurate outbreak reporting and disease surveillance, both veterinary and human, were very formidable undertakings (figure 4).

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    Figure 4. Getting to Bakmai meant an hour's hike through mountainous terrain

    In April, I was able to visit Luangphabang, the ancient royal capital that lies along the Mekong River and is surrounded by mountainous terrain inhabited by ethnic minorities who practice subsistence farming. The middle-class farmers around the city were typical of those I met in Laos. They were kind, warm, and with a sense of humour that easily crossed language and cultural barriers. They were very interested in exchanging suggestions and ideas on how to protect their flocks from H5N1. I learned as much from them as they from me.
    The pride of Luangphabang is its public buildings and temples, some of which date to the 16th century. But, Luangphabang also boasts a brand new provincial health centre, a cooperative project built through Chinese aid. As it turns out, I presented what had become an H5N1 awareness and preparedness workshop with the picture booklet as its core material. While sitting in this new facility, I wondered what the Chinese might say if they knew that the first person to speak at the facility was a USPHS veterinarian, encouraging Lao heath-care providers to be full participants in poultry disease surveillance as a tool for identifying H5N1 cases in human patients? This was my last site visit in Laos, and while I will cherish my memories of the entire experience, this work in Luangphabang best exemplified the inter-discipline bridging between veterinary and human public health needed to help prevent the emergence of a global H5N1 pandemic.
    The views expressed are those of the authors and should not be construed to represent the positions of the Department of Defense, or the Department of Health and Human Services. We have no conflicts of interest.


    a. Department of Defense Global Emerging Infections Systems (DoD-GEIS), MD, USA
    b. DoD-GEIS

    Correspondence to: Dr Clara Witt, Department of Defense Global Emerging Infections System, WRAIR 503 Robert Grant Ave, Silver Spring, MD 20910, USA

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