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Indian Journal ofCommunity MedicineOfficial Publication of Indian Association of Preventive and Social Medicine

www.ijcm.org.in

Apr-Jun 2010 / Vol 35 / Issue 2

ISSN 0970-0218

8/7/2019 Avian flu : Role Ducks -by Dr. Rajan R Patil

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209 Indian Journal of Community Medicine/Vol 35/Issue 2/April 2010

Address for correspondence:

Dr. Rajan R Patil, SRM University, Potheri, Kattankulathur – 603 203, Greater Chennai, India. E-mail: rajanpatil@yahoo.com

Received: 16-09-09, Accepted: 27-03-10, DOI: 10.4103/0970-0218.66854

The research work carried out in Vietnam and Thailandhas the potential to completely change our approach tothe bird u control. There is an increased understandingof avian u transmission and its control nowadays. TheGIS-Epidemiological work done in South East Asiancountries implicates ducks as the main source of birdu outbreaks.(1) Ducks-rice elds-human interactionis now recognized as responsible for the bird u are

ups in Asian countries. The present study takes intoconsideration this interaction as well as a set of vekey environmental variables comprising elevation,human population, chicken numbers, duck numbers,and rice cropping intensity for three synchronousepidemic waves in Thailand and Vietnam. A consistentpattern emerges, suggesting that risk is signicantlyassociated with duck abundance, human population,and rice cropping intensity in contrast to a relatively lowassociation with chicken numbers. It is interesting to notethat the study downplays chicken as the main source ofbird u. It unequivocally says that mass vaccination ofchicken is ineffective in controlling bird u in countries

like Vietnam.

This study is an attempt to discuss the above ndings inthe Indian context. First, we need to take these ndingscautiously as these studies are performed in the focalgeo-ecological setting of Vietnam, and therefore thendings may vary in Indian context. If we attempt acursory extrapolation of these ndings to Indian avianu outbreaks, ecologically at least, we could relate theWest Bengal outbreaks to the duck-rice eld-populationtheory. West Bengal is one of the top rice growing statesin India and culturally most of the rural. WB rural

households do have small ponds and rear ducks in theirbackyard. In the case of Maharashtra bird u outbreak,the duck-rice eld theory does not hold good, as thepieces of puzzle do not t in the case of Nandurbar andJalgaon districts in Maharashtra where the rst andsubsequent outbreak of bird u were reported fromIndia. These regions are dry and obviously rice is not the

main crop here. Moreover, these regions are famous forbanana plantations (Unlike West Bengal which leads inrice production, Maharastra is known for its horticultureprowess-mainly the production of mangoes, oranges,grapes, etc). Other major crops are cotton and sugarcane.Duck rearing is not prevalent in Maharashtra, as theycould only be reared in watery and marshy regions.

In the poultry sector, ducks form only about 10% of thetotal poultry population in India and contribute about6-7% of the total eggs produced in the country. Ducks aremostly concentrated in the Eastern and Southern Statesalong coastal regions of the country.(2) As having a coastalline, West Bengal (an Eastern state) is ideal for duckrearing. In contrast, Maharashtra (a Western state) is notknown for duck rearing, as they could only be reared inwatery and marshy regions. The subsequent paragraphsdeal with the distribution of chickens across India andoccurrence of the bird flu outbreak and investigateany possible pattern if any. The distribution of poultrypopulation suggests that 42% of the total population

of poultry birds is conned to Southern region, 22% inthe Eastern region, and 20% in Western region and theremaining 16% in the Northern region.(3)

Interestingly, the pattern shows negative correlation,that is, no bird u is reported from areas having highestpoultry concentration, whereas bird u is reported fromareas having least poultry concentration. Nearly half ofthe poultry come from Southern India (Andhra Pradeshis the No 1 in poultry rearing in India), yet entire regionremained free from bird flu outbreak. Maharashtrastate which reported rst outbreak of avian u is in the

Western region which has the least concentration ofpoultry in India.

The rice-ducks-human interaction offers explanationfor West Bengal’s vulnerability to bird u visa vie as atop rice producing and duck rearing state but fails toaccount for Maharashtra outbreaks. Although rice-duck-

View Point

Avian Flu: Examining Role of Ducks in IndianContext

Rajan R Patil

Division of Epidemiology, School of Public Health, SRM University, Chennai, India

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8/7/2019 Avian flu : Role Ducks -by Dr. Rajan R Patil

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Indian Journal of Community Medicine/Vol 35/Issue 2/April 2010 210

Patil: Avian u and the role of ducks

human theory partially correlates with Indian bird uscenario, it raises many new questions, for example, ifrice ducks are pre-requisite, then the Southern states ofAndhra Pradesh, Tamil Nadu should have been morevulnerable for their rice and duck production statusalong Southern Coast.

In the global scenario as well, the rice-duck-humantheory appears to correlate well with South East Asiancountries. These countries are the main rice producingnations in the world and incidentally avian u originatedin this region and continues to be the epicenter for avianu. The top ten rice producing nations in the world areChina, India, Indonesia, Bangladesh, Vietnam, Thailand,Myanmar, Philippines, Japan, Brazil and 90% of theworld’s 1044 billion domestic ducks are in Asia, with775 million of them (75%) are in China and Vietnam.

But how do we account for bird u outbreaks in theEuropean countries and other continents where neither

rice nor ducks are the mainstay production? The strengthof this theory is its validity and appears to have goodcorrelation with spatial and temporal evolution of avianu visa vie rice elds and duck rearing. At the same time,we should be awakened to the fact that these types ofstudies come under the category of ecological studiesand are prone of ecological fallacy.

References

1. Gilbert M, Xiao X, Chaitaweesub P, Kalpravidh W, PremashthiraS, Boles S, et al . Avian influenza, domestic ducks and riceagriculture in Thailand. Agric Ecosyst Environ 2007;119:409–15.

2. Contribution of ducks in overall poultry business in India.Available from: http://www.cpdosrbng.kar.nic.in/DUCK%20FARMING%20GUIDE.pdf. [cited in 2009 Oct 15].

3. Distribution of poultry population region-wise in India. Availablefrom: http://www.poulvet.com/poultry/articles/economic_study.php. [cited in 2009 Oct 15].

Source of Support: Nil, Conict of Interest: None declared.

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