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Coping with avian

Avian influenza, or “ flu”, is a contagious of The World Health Organization has animals caused by that normally infect only and, offered the following classification for less commonly, . While all bird species are thought to be the various phases [Table 2] in an susceptible to infection, domestic flocks are especially avian flu pandemic situation.[1] vulnerable to infections that can rapidly reach epidemic proportions. The disease in birds has two forms. The first Currently most countries affected are causes mild illness, sometimes expressed only as ruffled in the pandemic alert period of phase feathers or reduced egg production. Of greater concern is the 3 where there is still no clear cut second form, known as “highly pathogenic ”. evidence of to human This form, which was first recognized in in 1878, is transmission. WHO has also outlined extremely contagious in birds and rapidly fatal, with a the overarching public health goals for mortality approaching 100%. Birds can die on the same day these phases which are enumerated that symptoms first appear. The disease can spread from as above. to farm within a country as also be carried by migratory fowl across the world. The avian flu viruses spread through poultry So, do we have a threat of human flocks either via respiratory secretions or contact with pandemic influenza now? While no contaminated faeces. A single gram of contaminated faeces one can predict accurately when the has enough viruses to infect one million birds. pandemic will happen there is no doubt that we are on the threshold of The current concern amongst public health officials is a human flu pandemic. The WHO prompted by the fact that most major outbreaks of Avian flu mentions that best case scenarios recently reported have been caused by the highly pathogenic modeled on the mild pandemic of 1968 H5N1 . There is mounting evidence that this strain has project global excess deaths in the a unique capacity to jump the species barrier and cause range of 2 to 7.4 million.[2] There are severe disease, with high mortality, in . A bigger others who mention that clinical, concern is the possibility that the present situation could give epidemiological and laboratory rise to another in humans. Scientists are evidence suggest that a pandemic aware that avian and human influenza viruses can exchange caused by the H5N1 strain would be when a person is simultaneously infected with viruses more likely to mimic the 1918 from both species. This process of swapping inside the pandemic than those that occurred human body can give rise to a completely new subtype of the more recently, resulting in far higher influenza to which few, if any, humans would have mortality.[3] natural immunity. And, an alarming situation would rise if person-to-person transmission resulted in successive To reach the critical phase of the generations of severe disease with high mortality. This was human pandemic the virus must the situation during the great influenza pandemic of 1918– satisfy three components. (1) an ability 1919, when a completely new influenza virus subtype emerged to infect human beings; (2) a and spread around the globe, in around 4 to 6 months. Several vulnerable population without innate waves of infection occurred over 2 years, killing an estimated immunity and (3) rapid efficient 40–50 million persons. person-to-person transmission. H5N1 has met the first two criteria. It is only Currently the H5N1 strain has resulted in a few cases of a matter of time before the H5N1 virus humans being infected with the virus. However these cases picks up the genes necessary for rapid have been due to factors like close proximity to the fowl or person-to-person transmission. When eating improperly cooked meat prepared from affected this occurs, quarantine will not halt poultry. The cumulative number of confirmed cases of Avian the spread of the virus. The disease Influenza (H5N1) reported to WHO as on 09 November 2005 can be transmitted before symptom stands as under [Table 1]: onset and is highly contagious during

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Table 1: Total number of cases includes number of deaths. WHO reports only laboratory-confirmed cases Date of onset Total cases deaths cases deaths cases deaths cases deaths cases deaths 26.12.03-10.03.04 0 0 23 16 12 8 0 0 35 24 19.07.04-08.10.04 0 0 4 4 5 4 0 0 9 8 16.12.04- to date 9 5 65 22 3 1 4 4 81 32 Total 9 5 92 42 20 13 4 4 125 64

Table 2: WHO classification of phases in avian flu pandemic

the first few days of the illness.4 It is also expected that rapid ).[6] These class of drugs are however quite global spread of H5N1 will occur through air travel.[5] expensive and in a pandemic there may not be enough supplies to go around unless the drugs are manufactured This brings us to the all important aspect dealing with the locally in . The world is also waiting for the production prevention and control of such a pandemic. It has been shown of a vaccine which will be effective against the H5N1 strain. that while the H5N1 virus is resistant to antiviral compounds Manufacturing capacity for influenza vaccines is concentrated which are M2 inhibitors, the virus is susceptible to the class in Australia, , and North America but it seems of antiviral neuramidase inhibitors (Oseltamavir and unlikely that vaccines will be available till a few months into

Indian Journal of Occupational and Environmental Medicine - December 2005 - Volume 9 - Issue 3 100 Rajgopal T: Coping with Pandemic Avian Influenza the onset of the pandemic. The use of reverse genetics for flu rapid development of influenza vaccines as a means to • Individuals who have been in contact with poultry respond to pandemic threat seems to offer an appropriate • Health care providers technology that can cope with demand for vaccines in the • Diagnosed / confirmed cases of Avian flu event of a pandemic.[7] • Un-immunized people in high risk groups: to ameliorate illness and reduce complications, hospital admissions and From the perspective of a practicing occupational health deaths physician in charge of the health of all employees in an • Immunized people: if emerging information suggests that industry we can take the following steps to prevent / control the vaccine is not effective at reducing serious illness, avian influenza. complications or deaths

1. Vaccinate all employees with the current available strain It must be mentioned here that this drug is likely to be effective of . While this will not protect against the if taken in the very early phase (within two days of the avian flu it will ensure that in the event of any outbreak any condition). Therapy with (Tamiflu or a local case of influenza in the vaccinated populace should be viewed equivalent) should start within 48 hours after the onset of with suspicion - which can then help in decision making vis- influenza symptoms and the current recommended dosage à-vis treatment with the Oseltamavir(Tamiflu). is 75 mg tablets twice daily for five days. As a prophylaxis Companies should also advise suppliers / 3Ps on the best the current view is that the drug can be taken for a maximum practice in this area for them to take appropriate action at period of 6 weeks while in a pandemic the “waves” could last their end. for 8 – 12 weeks. The recommended dosage for prophylaxis • If a vaccine against the specific strain of H5N1 becomes is 75 mg. once a day. For severe cases the inhaled Zanamivir available then industries should offer this protection to (Relenza) is also advocated. all employees. At present there is no vaccine available against Avian flu. While trials are still going on, it is likely The current advice from various health authorities is to that the vaccine will be available only a few months after stockpile supply of Oseltamavir for 30% of the staff. In the the onset of the pandemic. event of a pandemic there will be immense pressure on • From a public health perspective groups prioritized for operating companies and they should have clear plans with vaccination should be (1) health care workers most at risk respect to: (2) essential services workers (3) at risk groups (4) • Business Continuity enclosed communities and (5) general population.[8] • Ensuring availability of the antiviral drug Oseltamavir (Tamiflu or a locally made equivalent ) 2. During the phase of the human pandemic it is recommended • Laid down policy to deal with an outbreak that employees with fever of > 38 degrees C. stay away from work till they are symptom and fever free. Such cases should Apart from the specific medical interventions, key non- be reviewed by appropriate medical personnel (The industry medical interventions should include stress on personal local medical advisor would be able to coordinate this). hygiene, wearing of appropriate masks (N-95 or N-100 with exhalation valve). At the population level contact tracing and 3. A health education and hygiene awareness campaign be screening of travelers at both the national and international started to cover all employees. levels are essential to prevent transmission. The country’s health system will be stretched to its limit with respect to 4. It would be useful to have in place guidelines covering the both preventing cases as well as taking care of the affected following: people. • Who will be eligible to receive the antiviral drug Oseltamavir ? e.g. treatment modality The threat of the pandemic is real. We as occupational health • Travel restrictions and their scope physicians have a significant role to play to mitigate the • Evacuation of non-essential staff morbidity and mortality arising out of such a pandemic. It • Policy on absenteeism will be essential for companies to put in place a • Personal protective measures comprehensive pandemic preparedness plan as well as business continuity plans. Close co-operation with 5. With respect to the specific aspect of treatment, since the governmental health agencies is also essential. It must be drug Oseltamavir will be in short supply the recommendation mentioned here that the Indian health authorities are seized is to prioritize the drug delivery to: of the potential pandemic and are gearing up to meet this • Individuals in close contact with known cases of Avian threat.

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REFERENCES pandemic influenza preparedness plan. Annex 7. Antiviral strategies and use. http:/www.hhs.gov/nvpo/pandemicplan/ (accessed 11th No- 1. World Health Organization. WHO Global Influenza Preparedness plan. vember 2005). The role of WHO and recommendations for national measures before 7. Webby RJ, Perez DR, Coleman JS, GuanY. Responsiveness to a pan- demic alert: use of reverse genetics for rapid development of influ- and during . WHO/CDS/CSR/GP/2005.5. enza vaccines. Lancet 2004;363:1099-103. 2. World Health Organization. Avian Influenza: Assessing the Pandemic 8. Explaining Pandemic Influenza. A guide from the Chief Medical Of- threat..January 2005. WHO/CDS/2005.29. ficer, Department of Health, NHS: UK; 2005. 3. Osterholm MT. Preparing for the next pandemic. N Eng J Med 2005;352:1839-42. 4. Mermel LA. Pandemic avian influenza. Lancet Infect Dis 2005;5:666- T. Rajgopal 7. Vice President, Medical and Occupational 5. Hufnagel L, Brockmann D, Geisel T. Forecast and control of epidem- Health, Hindustan Lever Limited, Head of ics in a globalized world. Proc Nat Acad Sci USA 2004;101:1524-9. Occupational Health , Unilever, Mumbai, India. 6. United States Department of Health and Human Services. National E-mail: [email protected]

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