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Volume 27, Number 9—September 2021

Risk Factors for Middle East Respiratory Syndrome Coronavirus Infection among Camel Populations, Southern Jordan, 2014–2018

Peter HollowayComments to Author , Matthew Gibson, Neeltje van Doremalen, Stephen Nash, Tanja Holloway, Michael Letko, Jacqueline M. Cardwell, Bilal Al Omari, Ahmad Al-Majali, Ehab Abu-Basha, Punam Mangtani, Vincent J. Munster, and Javier Guitian
Author affiliations: The Royal Veterinary College, Hatfield, UK (P. Holloway, J.M. Cardwell, J. Guitian); Glasgow University, Glasgow, Scotland, UK (M. Gibson); National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, USA (N. van Doremalen, M. Letko, V.J. Munster); London School of Hygiene and Tropical Medicine, London, UK (S. Nash, T. Holloway, P. Mangtani); Jordan University of Science and Technology, Irbid, Jordan (B. Al Omari, A. Al-Majali, E. Abu-Basha)

Main Article

Table 4

Multivariate associations between potential risk factors and Middle East respiratory syndrome coronavirus seropositivity in camel populations, southern Jordan, October 2017–October 2018

A priori adjusted OR (95% CI)†
p value
Fully adjusted OR (95% CI)‡
p value
Age, per y§
1.60 (1.35—1.99)
1.60 (1.34—1.92)
Camels borrowed for breeding purposes
4.46 (1.29—21.68)
5.07 (1.37—18.75)
Water source¶
Open ad lib Referent 0.07 Referent 0.05
Household only 3.17 (0.44—25.78) 3.33 (0.51—21.71)
Trough only
7.93 (1.41—65.04)

9.48 (1.54—58.24)

3.28 (0.92—14.94)
3.83 (1.01—14.51)
Herd size
Increasing individual camel nos.
1.02 (1.00—1.05)
1.00 (1.00—1.05)
1.70 (0.59—4.88)
1.38 (0.48—3.97)
No. camel herds within a 15-min drive
3.33 (0.77—17.53)
2.40 (0.53—10.84)
Herd is kept together as single group throughout the year
2.24 (0.61. 9.85)

Herd has contact with other local herds
2.34 (0.65—9.85)

Camel is a racing camel§
0.73 (0.13—4.33)

Camels are lent for breeding purposes
2.39 (0.66—10.70)

Closed herd# 0.07 (0.01—0.43) 0.01 0.08 (0.01—0.55) 0.02

*Variables reference the 1-year period before sampling, with the exception of herd size, camel is a racing camel, and a priori variables: age, sex, and region. Because of the potential influence of maternal immunity, camels <6 m of age have been excluded. †Adjusted for a priori variables: age, sex, and region. ‡2017–2018 study was adjusted for a priori variables and number of camels nearby (within a 15 min drive), herd is kept as a single group throughout the year, herd has contact with other local herds, and camel is a racing camel. §Individual camel–level variables (all other variables being herd-level). ¶Open ad lib indicates irrigation reservoir or spring water sources were used; household only indicates water source was not shared between household and herd; trough only indicates only tanker, tap, or well sources were used. #Closed herd indicates herd owners answered no to all of the following variables: borrowing, lending, purchasing, racing, and contact with local or distant herds (2017–2018 study only, missing data 2014–2015). Because of collinearity with constituent variables, the variable closed herd was included in a separate multivariate model from camels are borrowed for breeding purposes and camels are lent for breeding purposes. In this model, all variables listed continued to demonstrate significant association (p<0.05) with Middle East respiratory syndrome coronavirus seropositivity, with the exception of water source (p = 0.07).

Main Article

Page created: June 22, 2021
Page updated: August 17, 2021
Page reviewed: August 17, 2021
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