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Volume 31, Number 9—September 2025

Research

Drivers of Crimean-Congo Hemorrhagic Fever in Natural Host and Effects of Control Measures, Bulgaria

Georgina LimonComments to Author , Simona R. Tchakarova, Anna Ludi, Tsviatko Alexandrov, Iva Christova, Petya Petkova, Emmanuel Maze, Kelly Thomas, Natalie Baker, Marion England, Clare Browning, Ginette Wilsden, Sandra Belij-Rammerstorfer, Teresa Lambe, Anna Jolles, Miles Carroll, Roger Hewson, Simon Gubbins, Bryan Charleston, and Nicholas A. Lyons
Author affiliation: The Pirbright Institute, Pirbright, UK (G. Limon, A. Ludi, E. Maze, M. England, C. Browning, G. Wilsden, S. Gubbins, B. Charleston, N.A. Lyons); Bulgarian Food Safety Agency, Sofia, Bulgaria (S.R. Tchakarova, T. Alexandrov, P. Petkova); National Center of Infectious and Parasitic Diseases, Sofia (I. Christova); UK Health Security Agency Porton Down, Salisbury, UK (K. Thomas, N. Baker, R. Hewson); University of Oxford, Oxford, UK (S. Belij-Rammerstorfer, T. Lambe, M. Carroll); Pandemic Science Institute, Oxford (T. Lambe, M. Carroll); Oregon State University, Corvallis, Oregon, USA (A. Jolles); London School of Hygiene and Tropical Medicine, London, UK (R. Hewson)

Main Article

Table 1

Results from multivariable mixed-effect models used to assess serologic associations in study of Crimean-Congo hemorrhagic fever in sheep and effects of control measures, Bulgaria*

Characteristic CCHFV glycoprotein Gc IgG positive
 CCHFV nucleoprotein IgG positive
aOR (95% CI) p value aOR (95% CI) p value
Study type
Follow-up, March 2018, n = 58 Referent Referent
Cross-sectional, Oct 2017, n = 140
 1.31 (0.64–2.75)
 0.464
14.49 (5.54–46.93)
 <0.001
Age category
13–24 mo., young adult sheep, n = 115 Referent Referent
3–12 mo., lambs, n = 83 1.44 (0.74–2.82) 0.283 1.8 (0.94–3.68) 0.073

*Associations between CCHFV glycoprotein Gc or nucleoprotein seropositivity and time of sampling (study type) and age; only farms visited during both field studies 1 and 2 (n = 14) and sheep of the same age (3–24 mo) (total no. = 198) were considered. Models had farm as a random effect. Results from univariate analysis are in the Appendix Tables 1, 2. aOR, adjusted odds ratio; CCHFV, Crimean-Congo hemorrhagic fever virus.

Main Article

Page created: July 03, 2025
Page updated: August 26, 2025
Page reviewed: August 26, 2025
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