Crimean-Congo haemorrhagic fever virus in ticks collected from livestock in Balochistan, Pakistan.

BACKGROUND: Crimean-Congo haemorrhagic fever virus (CCHFV) is a tick-borne zoonotic pathogen. It causes a fatal haemorrhagic disease in humans. Hard ticks, in particular Hyalomma spp., are considered to function as reservoir as well as vector for CCHFV. METHODS: A cross-sectional study was conducted in the province of Balochistan, Pakistan, from September to November 2017. Ticks were collected from cattle, sheep and goats in livestock farms. The ticks were morphologically identified, followed by confirmation with molecular methods (PCR and sequencing). Furthermore, ticks were examined for CCHFV genomes (S segment) by a one-step multiplex real-time RT-qPCR and positive samples were sequenced to determine the CCHFV genotype. RESULTS: In total, 525 of 529 livestock infesting adult ticks belonged to the genus Hyalomma, and 4 ticks to the genus Rhipicephalus (R. microplus 3×, R. turanicus 1×). In the genus Hyalomma, H. marginatum (28%), H. excavatum (26%), H. dromedarii (22%), H. anatolicum (16%) and H. scupense (8%) ticks were identified. Tick infestations were as follows: sheep 58%, goats 28% and cattle 14%. Four per cent (20/525) of ticks were CCHFV genome-positive, and all genomes clustered in CCHFV genotype Asia 1. Among CCHFV-positive ticks, 75% (15/20) were female and 25% (5/20) male. CCHFV genomes were most frequently detected in H. marginatum (30%, 6/20), followed by H. dromedarii (25%, 5/20), H. excavatum (20%, 4/20), H. anatolicum (20%, 4/20) and H. scupense (5%, 1/20). All CCHFV-positive ticks were found on sheep. The largest number of CCHFV-positive ticks were detected in the district of Kalat (60%, 12/20), followed by the districts of Quetta (30%, 6/20) and Killa Abdullah (10%, 2/20). CONCLUSIONS: This study confirms the circulation of CCHFV in ticks in Balochistan, south-western Pakistan. It is imperative to take effective tick control measures in this area, especially to control livestock tick infestations to prevent CCHF infections in humans.

Epidemiological investigations of Crimean-Congo haemorrhagic fever virus infection in sheep and goats in Balochistan, Pakistan.

Crimean-Congo haemorrhagic fever (CCHF) is a tick-borne zoonotic disease caused by the arbovirus Crimean-Congo haemorrhagic fever virus (CCHFV). Livestock serve as a transient reservoir for CCHFV, but do not show clinical signs. In this cross-sectional study, sheep and goats in Balochistan, Pakistan, were examined to determine the CCHFV seroprevalence, spatial distribution of seropositive sheep and goats, and to identify potential risk factors for seropositivity to CCHFV in these animals. To this end, farms and animals were selected by systematic sampling, blood samples from 800 sheep and 800 goats were collected and information regarding farm management and the kept animals were retrieved using a standard questionnaire. Sera were tested for antibodies against CCHFV in two independent ELISA formats and an immunofluorescence assay (IFA) following a hierarchical diagnostic decision tree. By these assays 149 (19 %, 95 %-CI: 16-21 %) out of 800 sheep serum samples and 37 (5 %, 95 %-CI: 3-6 %) out of 800 goat serum samples were positive for CCHFV-specific IgG antibodies. Interestingly, at least 8 (5 %, 95 %-CI: 2-10 %) out of 160 sera pools were from CCHFV viraemic sheep, as sera (in pools of 5) tested positive for CCHFV genome by real-time PCR (RT-qPCR). Risk factor analysis revealed that the open type of housing (OR = 3.76, 95 %-CI:1.57-9.56, p-value = 0.003), grazing (OR = 4.18, 95 %-CI:1.79-10.37, p-value = 0.001), presence of vegetation in or around the farm (OR = 3.13, 95 %-CI: 1.07-10.15, p-value = 0.043), lack of treatment against ticks (OR = 3.31, 95 %-CI: 1.16-10.21, p-value = 0.029), absence of rural poultry (OR = 2.93, 95 %-CI: 1.41-6.29, p-value = 0.004), animals with age ≥ 2 years (OR = 4.15, 95 %-CI: 2.84-6.19, p-value<0.001), animals infested with ticks (OR = 2.35, 95 %-CI: 1.59-3.52, p-value<0.001), and sheep species (OR = 4.72, 95 %-CI:3.24-6.86, p-value<0.001) represented statistically significant risk factors associated with seropositivity to CCHFV. Taken together this study confirms the circulation of CCHFV in livestock in Balochistan, Pakistan. The identification of risk factors might help to reduce the risk of infection in sheep and goats, which may also mitigate the risk for human infection. An interesting option for reducing the risk of CCHFV infection in small ruminants is keeping also chickens, since they pick ticks that transmit CCHFV.

High seroprevalence for Crimean-Congo haemorrhagic fever virus in ruminants in the absence of reported human cases in many regions of Bulgaria.

Crimean-Congo haemorrhagic fever (CCHF) is a severe tick-borne zoonotic disease in humans caused by CCHF virus. It has been observed in Bulgaria since 1952 and over the years more than 1600 cases have been reported in the country. Close contact with viraemic livestock was shown as one of the main causes of the infection. Detection of CCHF virus specific antibodies in livestock can be used as an indicator for virus circulation and risk assessment. CCHF seroprevalence was investigated in 843 cattle, 88 goats and 130 sheep, originating from all 28 districts of Bulgaria. CCHF virus-specific IgG antibodies were observed in 165 cattle (19.6, 95% CI 17.0-22.4%), in 20 goats (22.7, 95% CI 15.2-32.5%) and in 10 sheep (7.7, 95% CI 4.2-13.6%). The highest seroprevalence was detected in the district of Kardzhali, South Bulgaria (86.7, 95% CI 73.8-93.7%), a well-known focus of CCHF in humans. The other two districts with human CCHF cases, Blagoevgrad and Burgas, located in southwest and southeast Bulgaria, showed overall seroprevalences in livestock of 41.9% (95% CI 28.4-56.7%) and 31.3% (95% CI 22.2-42.1%), respectively. Seroprevalences in districts with no history of human CCHF cases varied between 55% (95% CI 39.8-69.3%) and 22.5% (95% CI 12.3-37.5%). These results suggest frequent CCHF virus infections even in regions without human CCHF cases and an enhanced risk of infection for humans in close contact with the infected livestock.

Serosurvey of Crimean-Congo Hemorrhagic Fever Virus in Cattle, Mali, West Africa.

AbstractCrimean-Congo hemorrhagic fever is a tick-borne disease caused by the arbovirus Crimean-Congo hemorrhagic fever virus (CCHFV, family Bunyaviridae, genus Nairovirus). CCHFV can cause a severe hemorrhagic fever with high-case fatality rates in humans. CCHFV has a wide geographic range and has been described in around 30 countries in the Middle East, Asia, Europe, and Africa including Mali and neighboring countries. To date, little is known about the prevalence rates of CCHFV in Mali. Here, using banked bovine serum samples from across the country, we describe the results of a seroepidemiological study for CCHFV aimed at identifying regions of circulation in Mali. In total, 1,074 serum samples were tested by a modified in-house CCHFV-IgG-enzyme-linked immunosorbent assay (ELISA) with confirmatory testing by commercial ELISA and immunofluorescence assay. Overall, 66% of samples tested were positive for CCHFV-specific IgG antibodies. Regional seroprevalence rates ranged from 15% to 95% and seemed to correlate with cattle density. Our results demonstrate that CCHFV prevalence is high in many regions in Mali and suggest that CCHFV surveillance should be established.