Prevalence of Crimean-Congo hemorrhagic fever virus in ticks collected from Kaseese and Luweero in Uganda

Abstract

Crimean-Congo Hemorrhagic Fever virus is a tick-borne negative sense single stranded RNA virus that causes a zoonotic disease; Crimean-Congo Hemorrhagic Fever. To determine the prevalence of CCHF virus in ticks, retrospective study was conducted in 214 tick pools that were obtained from about 3201 ticks that were collected from food animals (sheep, goats and cattle), pet animals (cats and dogs) and from grass (questing ticks) from the two districts Kasese and Luwero from March to September, 2022, during an Acute Febrile Illness surveillance done in vectors by MUWRP-EIDP. Detection of the virus in ticks was done using reverse transcriptase real time polymerase chain reaction. Real time PCR with high specificity and less likelihood of contamination was used to detect and amplify the partial S-segment that codes for the N-protein of CCHF virus. The statistical significance was calculated to determine the statistical significance of the study. A total of 214 pools obtained comprised of three tick species 92 (43%) Rhipicephalus appendiculatus, 47 (22%) Rhipicephalus decoloratus and 42 (19.6%) Haemphysalis elliptica and 33 (15.4%) tick nymphs were obtained and were screened for Crimean Congo Hemorrhagic Fever virus using reverse transcriptase real time polymerase reaction. Of the 214 tick pools tested 4 (1.87%), 95% CI (0.055-3.685) tested positive for the virus while 210 were negative. CCHF virus was detected in three species Rhipicephalus appendiculatus, Rhipicephalus decoloratus and Haemphysalis elliptica, with prevalence of 2.1%, 1.1% and 4.8% respectively. All the positives were obtained from adult tick pools hence a prevalence of 2.2% that was statistically significant. CCHF virus is prevalent in Rhipicephalus appendiculatus, Rhipicephalus decoloratus, and Haemphysalis elliptica ticks and from both sites in Uganda which poses a risk to livestock farmers and other people that associate with such animals.