Risk factors for Crimean-Congo Haemorrhagic Fever (CCHF) virus exposure in farming communities in Uganda

Highlights

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  Risk factors for zoonotic transmission of Crimean-Congo Haemorrhagic fever Virus (CCHFV) among livestock farming communities in Uganda.

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  Extremely high CCHFV seroprevalence was detected in humans and domestic animals in Uganda

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  The burden of CCHFV infection and risk factors has to date been underestimated in Uganda.

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  Detection of CCHV in multiple pools of Rhipicephalus appendiculatus suggest these ticks to be the likely vectors for CCHFV in Uganda

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  CCHFV risk in humans were associated with livestock rearing, age and collecting/ eating ticks

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  Further work is indicated to estimate the incidence of CCHFV infection as a cause of non-malarial fever

Abstract

Background

Crimean-Congo Haemorrhagic Fever (CCHF) is an emerging human-health threat causing sporadic outbreaks in livestock farming communities. However, the full extent and the risks associated with exposure of such communities has not previously been well-described.

Methods

We collected blood samples from 800 humans, 666 cattle, 549 goats and 32 dogs in districts within and outside Ugandan cattle corridor in a cross-sectional survey, and tested for CCHFV-specific IgG antibodies using Enzyme-Linked Immunosorbent Assays. Sociodemographic and epidemiological data were recorded using structured questionnaire. Ticks were collected to identify circulating nairoviruses by metagenomic sequencing.

Results

CCHFV seropositivity was in 221/800 (27·6%) in humans, 612/666 (91·8%) in cattle, 413/549 (75·2%) in goats and 18/32 (56·2%) in dogs. Human seropositivity was associated with livestock farming (AOR=5·68, p<0·0001), age (AOR=2·99, p=0·002) and collecting/eating engorged ticks (AOR=2·13, p=0·004). In animals, seropositivity was higher in cattle versus goats (AOR=2·58, p<0·0001), female sex (AOR=2·13, p=0·002) and heavy tick infestation (>50 ticks: AOR=3·52, p=0·004). CCHFV was identified in multiple tick pools of Rhipicephalus appendiculatus.

Interpretation

The very high CCHF seropositivity especially among livestock farmers and multiple regional risk factors associated exposures, including collecting/eating engorged ticks previously unrecognised, highlights need for further surveillance and sensitisation and control policies against the disease.