Prevalence of Crimean-Congo haemorrhagic fever in livestock following a confirmed human case in Lyantonde district, Uganda

Abstract

Background Crimean-Congo haemorrhagic fever (CCHF) is a tick-borne viral infection, characterized by haemorrhagic fever in humans and transient asymptomatic infection in animals. It is an emerging human health threat causing sporadic outbreaks in Uganda. We conducted a detailed outbreak investigation in the animal population following the death from CCHF of a 42-year-old male cattle trader in Lyantonde district, Uganda. This was to ascertain the extent of CCHF virus (CCHFV) circulation among cattle and goats and to identify affected farms and ongoing increased environmental risk for future human infections. Methods We collected blood and tick samples from 117 cattle and 93 goats, and tested these for anti-CCHFV antibodies and antigen using an enzyme-linked immunosorbent assay (ELISA), quantitative reverse transcriptase polymerase chain reaction (qRT-PCR) and target enrichment next generation sequencing. Results CCHFV-specific IgG antibodies were detected in 110/117 (94.0%) cattle and 83/93 (89.3%) goats. Animal seropositivity was independently associated with female animals (AOR = 9.42, P = 0.002), and animals reared under a pastoral animal production system (AOR = 6.02, P = 0.019] were more likely to be seropositive than tethered or communally grazed animals. CCHFV was detected by sequencing in Rhipicephalus appendiculatus ticks but not in domestic animals. Conclusion This investigation demonstrated very high seroprevalence of CCHFV antibodies in both cattle and goats in farms associated with a human case of CCHF in Lyantonde. Therefore, building surveillance programs for CCHF around farms in this area and the Ugandan cattle corridor is indicated, in order to identify opportunities for case prevention and control. Graphical Abstract

Ticks; a reservoir for virus emergence at the human-livestock interface in Uganda

“…We also selected an area (Arua district) outside the cattle corridor (24,29,37,38), classified as a low-risk area where CCHF had never previously been reported, as a control site. The study in Lyantonde coincided with a CCHF outbreak, and ecological sampling of ticks for virome analysis was undertaken as part of an outbreak investigation (39).…”

“…Thereafter, a randomized selection of households that kept livestock within the selected subcounties was made to reach a predetermined total of 1,215 livestock samples (40). In Lyantonde, farms were selected based on a trace back of a fatal case of CCHF in the district, to identify CCHFV spillover farm(s) associated with the outbreak (39). Tick samples were collected from a minimum of 25% of randomly selected animals on each farm.…”

Current status of Crimean‐Congo hemorrhagic fever outbreaks in Uganda and other African countries

“…In October 2022, Kaberamaido District in Eastern Uganda reported its first case of CCHF, the patient was recently admitted to Kaberamaido General Hospital. The patient is a resident of Abirabira village in the Aperkira sub–country, according to health officials 8 . Since 2010, Uganda has used a viral hemorrhagic fever surveillance system, where more than 20 sentinel surveillance stations are part of the program and samples from throughout Uganda as well as nearby nations are transported there for examination 8 …”

“…In subsequent years, additional confirmation of outbreaks defined as one or more cases has been made because of the expanded surveillance 9 . Based on a seroprevalence study conducted in 2020 in Uganda, it was determined that anti–CCHF antibodies are present and very prevalent in cattle 8 . The infection is linked to a geographical region, growing older, being female, and having a greater tick burden 10 .…”

Crimean-Congo Hemorrhagic Fever Survivors Elicit Protective Non-Neutralizing Antibodies that Target 11 Overlapping Regions on Viral Glycoprotein GP38

“…Transmission of CCHFV to humans, as well as to domesticated and wild animals, occurs primarily through the bite of Hyalomma ticks 3–5 . Direct contact with infected tissues, primarily due to contact with blood from infected livestock, can also result in transmission 6,7 , and, though less common, nosocomial infections have been reported 8,9 . The broad geographic range of Hyalomma ticks contributes to widespread outbreaks of CCHFV across at least three continents, including Europe, Asia, and Africa, where CCHFV is endemic 2,6,10,11 .…”