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Tropical Animal Health and Production

, Volume 44, Issue 7, pp 1643–1651 | Cite as

Epidemic characterization and modeling within herd transmission dynamics of an “emerging trans-boundary” camel disease epidemic in Ethiopia

  • Bekele MegersaEmail author
  • Demelash Biffa
  • Fufa Abunna
  • Alemayehu Regassa
  • Jon Bohlin
  • Eystein Skjerve
Original Research

Abstract

A highly acute and contagious camel disease, an epidemic wave of unknown etiology, referred to here as camel sudden death syndrome, has plagued camel population in countries in the Horn of Africa. To better understand its epidemic patterns and transmission dynamics, we used epidemiologic parameters and differential equation deterministic modeling (SEIR/D-model) to predict the outcome likelihood following an exposure of susceptible camel population. Our results showed 45.7, 17.6, and 38.6 % overall morbidity, mortality, and case fatality rates of the epidemic, respectively. Pregnant camels had the highest mortality and case fatality rates, followed by breeding males, and lactating females, implying serious socioeconomic consequences. Disease dynamics appeared to be linked to livestock trade route and animal movements. The epidemic exhibited a strong basic reproductive number (R 0) with an average of 16 camels infected by one infectious case during the entire infectious period. The epidemic curve suggested that the critical moment of the disease development is approximately between 30 and 40 days, where both infected/exposed and infectious camels are at their highest numbers. The lag between infected/infectious curves indicates a time-shift of approximately 3–5 days from when a camel is infected and until it becomes infectious. According to this predictive model, of all animals exposed to the infection, 66.8 % (n = 868) and 33.2 % (n = 431) had recovered and died, respectively, at the end of epidemic period. Hence, if early measures are not taken, such an epidemic could cause a much more devastative effect, within short period of time than the anticipated proportion.

Keywords

Contagious disease Camel sudden death Differential equation 

Notes

Acknowledgments

We are thankful to those who were involved in the disease investigations in general and Mr. Tilahun Nigusse in particular. The support of the Drylands Coordination Groups (DCG) of Norway to carry out an epidemiological study of major camel diseases in Borana, and the willingness of herdsmen to cooperate in sharing their knowledge and observations are gratefully acknowledged.

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Copyright information

© Springer Science+Business Media B.V. 2012

Authors and Affiliations

  • Bekele Megersa
    • 1
    Email author
  • Demelash Biffa
    • 1
  • Fufa Abunna
    • 1
  • Alemayehu Regassa
    • 1
  • Jon Bohlin
    • 2
  • Eystein Skjerve
    • 2
  1. 1.School of Veterinary MedicineHawassa UniversityHawassaEthiopia
  2. 2.Center for Epidemiology and BiostatisticsNorwegian School of Veterinary ScienceOsloNorway

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