Risk-Factors of Crimean-Congo Haemorrhagic Fever Across Six Tertiary Hospitals in Afghanistan from 2022 to 2025: Reported Exposures, Healthcare-Worker Clustering, and Ribavirin Treatment-Timing Analyses
- 1Independent Researcher, Kabul, Afghanistan.
Abstract
IntroductionCrimean-Congo haemorrhagic fever (CCHF) is endemic in Afghanistan, but multi-hospital data characterising reported exposure patterns, healthcare-worker clustering, and ribavirin-mortality associations after accounting for treatment timing are lacking.
MethodsA retrospective cohort study included 737 laboratory-confirmed CCHF patients admitted to six tertiary hospitals in Afghanistan between January 2022 and December 2025. Reported exposures were assessed by occupation and tick-contact history. Clustering of healthcare-worker (HCW) infections during high caseload was assessed by permutation testing. Ribavirin-mortality association was assessed using multivariable Cox regression adjusted for clinical severity, age, sex, hospital, and comorbidity, with sensitivity analyses addressing treatment timing immortal-time bias.
ResultsAmong 737 patients, the median age was 35 years and 78.3% were male. The hospitalization fatality ratio (HFR) was 27.7% (204/737). Of 574 patients with recorded occupation: 33.6% were livestock handlers, 12.9% slaughterhouse workers or butchers, 24.9% household meat preparers, and only 11.1% reported tick exposure. Nineteen patients were HCWs, and 18 became infected during periods of concurrent CCHF admissions, and clustering exceeded chance (p=0.012), consistent with healthcare-associated exposure during surges. Personal protective equipment (PPE) was used in 728 (98.6%) admissions, but its composition was incomplete: 532 (72.2%) comprised mask and gloves without a gown, and only 205 (27.8%) with mask, gloves, and gown. Isolation rooms were available for only 274 of 737 admissions (37.2%). Among 727 patients in the ribavirin analysis, 85.0% received treatment. Conventional analysis suggested lower mortality (adjusted HR 0.57) but affected by immortal-time bias. The association weakened for same-day treatment versus no treatment (HR 0.63, 95% CI 0.41-0.96; sensitive to model specification) and was absent in time-varying analysis (HR 0.93).
ConclusionCCHF in this hospitalised Afghan cohort was commonly associated with reported animal and livestock-related exposure, while healthcare-worker infections clustered during outbreak surges. Isolation capacity and caseload may be important correlates of healthcare-associated risk alongside PPE availability. Ribavirin findings were sensitive to treatment-timing adjustment and cannot establish a causal survival benefit.
Key QuestionsO_LIWhat is already known on this topic O_LICCHF is endemic in Afghanistan, but previous studies lacked individual-level multi-hospital data on reported transmission exposures, formal assessment of healthcare-worker clustering, and ribavirin treatment-timing analyses, while evidence from other endemic countries has been inconsistent. C_LI C_LIO_LIWhat this study adds O_LIIn 737 laboratory-confirmed cases across six tertiary hospitals, reported animal and livestock-related exposure was far more common than reported tick exposure, healthcare-worker infections clustered significantly during periods of high CCHF caseload and where isolation capacity was limited, and the apparent mortality benefit of ribavirin was substantially attenuated after accounting for treatment timing and immortal-time bias. C_LI C_LIO_LIHow this study might affect research, practice or policy O_LIThe findings support stronger public health interventions such as One Health prevention at the animal-human interface, investment in dedicated isolation capacity together with complete PPE during outbreak surges, protective equipment during slaughter and butchering, veterinary surveillance of viraemic livestock, and risk-reduction before Eid-al-Adha. C_LI C_LI
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BibTeX
@misc{zadran2026riskfactors,
title = {{Risk-Factors of Crimean-Congo Haemorrhagic Fever Across Six Tertiary Hospitals in Afghanistan from 2022 to 2025: Reported Exposures, Healthcare-Worker Clustering, and Ribavirin Treatment-Timing Analyses}},
author = {R. Zadran and M. N. Sahak and F. Arifi and Y. Chen and H. Sadat and G. Saraj and S. Essayagh and T. Essayagh and L. J. White and N. Hupert and S. Chen},
howpublished = {medRxiv},
year = {2026},
month = oct,
doi = {10.64898/2026.10.24.26366389},
url = {https://www.medrxiv.org/content/10.64898/2026.10.24.26366389v1},
note = {CC BY-NC-ND},
}
RIS
TY - UNPB
TI - Risk-Factors of Crimean-Congo Haemorrhagic Fever Across Six Tertiary Hospitals in Afghanistan from 2022 to 2025: Reported Exposures, Healthcare-Worker Clustering, and Ribavirin Treatment-Timing Analyses
AU - R. Zadran
AU - M. N. Sahak
AU - F. Arifi
AU - Y. Chen
AU - H. Sadat
AU - G. Saraj
AU - S. Essayagh
AU - T. Essayagh
AU - L. J. White
AU - N. Hupert
AU - S. Chen
PY - 2026
DA - 2026/10/24
PB - medRxiv
DO - 10.64898/2026.10.24.26366389
UR - https://www.medrxiv.org/content/10.64898/2026.10.24.26366389v1
AB - IntroductionCrimean-Congo haemorrhagic fever (CCHF) is endemic in Afghanistan, but multi-hospital data characterising reported exposure patterns, healthcare-worker clustering, and ribavirin-mortality associations after accounting for treatment timing are lacking. MethodsA retrospective cohort study included 737 laboratory-confirmed CCHF patients admitted to six tertiary hospitals in Afghanistan between January 2022 and December 2025. Reported exposures were assessed by occupation and tick-contact history. Clustering of healthcare-worker (HCW) infections during high caseload was assessed by permutation testing. Ribavirin-mortality association was assessed using multivariable Cox regression adjusted for clinical severity, age, sex, hospital, and comorbidity, with sensitivity analyses addressing treatment timing immortal-time bias. ResultsAmong 737 patients, the median age was 35 years and 78.3% were male. The hospitalization fatality ratio (HFR) was 27.7% (204/737). Of 574 patients with recorded occupation: 33.6% were livestock handlers, 12.9% slaughterhouse workers or butchers, 24.9% household meat preparers, and only 11.1% reported tick exposure. Nineteen patients were HCWs, and 18 became infected during periods of concurrent CCHF admissions, and clustering exceeded chance (p=0.012), consistent with healthcare-associated exposure during surges. Personal protective equipment (PPE) was used in 728 (98.6%) admissions, but its composition was incomplete: 532 (72.2%) comprised mask and gloves without a gown, and only 205 (27.8%) with mask, gloves, and gown. Isolation rooms were available for only 274 of 737 admissions (37.2%). Among 727 patients in the ribavirin analysis, 85.0% received treatment. Conventional analysis suggested lower mortality (adjusted HR 0.57) but affected by immortal-time bias. The association weakened for same-day treatment versus no treatment (HR 0.63, 95% CI 0.41-0.96; sensitive to model specification) and was absent in time-varying analysis (HR 0.93). ConclusionCCHF in this hospitalised Afghan cohort was commonly associated with reported animal and livestock-related exposure, while healthcare-worker infections clustered during outbreak surges. Isolation capacity and caseload may be important correlates of healthcare-associated risk alongside PPE availability. Ribavirin findings were sensitive to treatment-timing adjustment and cannot establish a causal survival benefit. Key QuestionsO_LIWhat is already known on this topic O_LICCHF is endemic in Afghanistan, but previous studies lacked individual-level multi-hospital data on reported transmission exposures, formal assessment of healthcare-worker clustering, and ribavirin treatment-timing analyses, while evidence from other endemic countries has been inconsistent. C_LI C_LIO_LIWhat this study adds O_LIIn 737 laboratory-confirmed cases across six tertiary hospitals, reported animal and livestock-related exposure was far more common than reported tick exposure, healthcare-worker infections clustered significantly during periods of high CCHF caseload and where isolation capacity was limited, and the apparent mortality benefit of ribavirin was substantially attenuated after accounting for treatment timing and immortal-time bias. C_LI C_LIO_LIHow this study might affect research, practice or policy O_LIThe findings support stronger public health interventions such as One Health prevention at the animal-human interface, investment in dedicated isolation capacity together with complete PPE during outbreak surges, protective equipment during slaughter and butchering, veterinary surveillance of viraemic livestock, and risk-reduction before Eid-al-Adha. C_LI C_LI
ER -