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Cite this article: Taraku A, Sas MA, Lugaj A, Bizhga B, Berxholi K, et al. (2018) Crimean-Congo Hemorrhagic Fever Virus Infections in Cattle in Kosovo. J Vet Med Res 5(1): 1119.

Journal of Veterinary Medicine and Research

*Corresponding authorMartin H. Groschup, Institute of Novel and Emerging Infectious Diseases at the Friedrich-Loeffler-Institut, Südufer 10, 17493 Greifswald-Island of Riems, Germany, Tel: 49-38351-7-1163; Email:

Submitted: 19 December 2017

Accepted: 25 January 2018

Published: 29 January 2018

ISSN: 2378-931X

Copyright© 2018 Groschup et al.

OPEN ACCESS

Keywords• Orthonairovirus; Nairoviridae; IgG antibodies; Cattle;

ELISA

Research Article

Crimean-Congo Hemorrhagic Fever Virus Infections in Cattle in KosovoArber Taraku1, Miriam Andrada Sas2, Arta Lugaj3, Bejo Bizhga4, Kristaq Berxholi4, and Martin H. Groschup2*1Faculty of Veterinary Medicine, Agricultural University of Tirana, Albania2Institute of Novel and Emerging Infectious Diseases, Federal Research Institute for Animal Health, Germany3Departments of Biology, University “Ismail Qemali”, Albania4Department of Preclinical Subjects, Agricultural University of Tirana, Albania

Abstract

Crimean-Congo hemorrhagic fever (CCHF) is a zoonotic vector-born viral disease named for the causative agent, Crimean-Congo hemorrhagic fever virus (CCHFV). CCHFV is a member of the family Nairoviridae, genus Orthonairovirus. The virus is mainly transmitted via tick bites. Other transmission pathways are contact to blood, other bodily fluids and tissues of viremic animals or human patients. The case fatality rate in humans lies between 2 and 80%. Unlike humans, animals do not show clinical signs but they develop a stable antibody titer after a short viremia (< 2 weeks). Hence, seroepidemiological studies in livestock are very useful as risk indicator for CCHF in humans. The aim of this study was to examine the distribution of CCHFV infections among cattle in different districts of Kosovo. This survey was carried out in 2013-2014. Blood samples were taken from the jugular vein of 932 cattle in Kosovo. These sera were collected from nine different districts of Kosovo (Suhareke, Rahovec, Malisheve, Kline, Decan, Drenas, Prizren, Peje and Gjakove) and were tested with different serological assays (ELISA and IFA) at Friedrich-Loeffler-Institut (FLI), Greifswald, Germany. Through these techniques it was possible to identify CCHFV-specific IgG antibodies in serum samples of infected animals. Specific IgG antibodies were detected in cattle from all sampled areas and detected prevalence were substantial in some districts (43, 64% in Malisheve, followed by 25.25% in Rahovec). The overall seroprevalence was 19.21% (179 positives), with major CCHFV risk areas in Malisheve and Rahovec.

ABBREVIATIONSCCHFV: Crimean-Congo Hemorrhagic Fever Virus;

FLI: Friedrich-Loeffler-Institut; ELISA: Enzyme-Linked Immunosorbent Assays; IFA: Immunofluorescence Assays

INTRODUCTIONThe Crimean–Congo hemorrhagic fever virus (CCHFV) is a

tick-borne virus belonging to the genus Orthonairovirus, family Nairoviridae of RNA viruses. The new genus Orthonairovirus includes 12 species, which are grouped in seven serogroups. CCHF serogroup contains CCHF virus and Hazara virus. CCHF virus circulates in nature in an enzootic tick-vertebrate-tick cycle. Ticks of the genus Hyalomma are the main vectors and reservoirs of the virus [1, 2-5] and define the worldwide distribution of CCHFV [2,3,6, 7]. In Europe, Hyalomma marginatum ticks play the most important role in CCHFV transmission. The geographic distribution of the diseases is closely linked to the distribution of Hyalomma ticks which are found up to 46°N (latitude North) [2,8,9]. Hence, humans become infected primarily when working outdoors or as health care workers with infected patients. Human cases have been reported from more than 30 countries of Asia, South-Eastern Europe and Africa [2,10]. In Turkey, more than 1,000 human CCHF cases are reported annually in some years of the last decade [10,11]. In Europe, human cases occur regularly

in Albania, Bulgaria and Kosovo, while infection rates and case numbers in most other countries are fairly unknown [10,12]. Clinical symptoms can be mild and flu-like but also severe hemorrhagic fevers do occur. Case fatality rates vary between 5% (Turkey) [13] and 80% (China) [14-16], depending on the circulating virus strain, the healthcare system and the general awareness. In contrary to humans, other mammals do not show any signs of illness but elicit IgG antibodies after a short viremia and therefore can serve as risk indicators for CCHF circulating in the environment. CCHFV is endemic in Kosovo, which is a landlocked country with a surface area of 10,877 km2 in the center of the Balkan Peninsula and has borders with Macedonia, Albania, Serbia and Montenegro [17]. The first cases of CCHF in Kosovo were registered in 1954 in Nishor village (three fatal cases) [17,18] and in 1957 a family outbreak leading to eight fatalities was described [19]. Cases were again detected in 1989 (7 cases) and 1991 (9 cases). Since 1992 the disease has been considered to be present in sporadic or epidemic form, notably with an outbreak in 1995 (46 cases) [20]. Based on the records of the Institute of Public Health of Kosovo, from 1995 to August 2013, 228 cases of CCHF have been reported in Kosovo, with the fatality rate of 25.5% [21]. Whereas human clinical cases have been studied extensively, there is only limited knowledge about the overall seroprevalence of the disease in Kosovo [21-24].

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MATERIALS AND METHODSSerum samples

This survey was carried out in 2013-2014 in 9 municipalities of Kosovo. Blood samples were taken from the jugular vein of 932 cattle in (Suhareke, Rahovec, Malisheve, Kline, Decan, Drenas, Prizren, Peje and Gjakove). Serum samples were collected in regions where human cases already occurred as refer to the figure below.

Serological analysis

All collected sera were tested using a cattle specific in-house CCHFV-IgG-ELISA [as described before (10, 25)]. Samples with a positive or inconclusive result in the in-house ELISA were rerun

in cattle adapted commercial CCHFV-IgG-ELISA (Vector-Best, Novosibirsk, Russia). In case of divergent results, samples were re-tested again in a cattle adapted commercial CCHFV-IgG-IFA (Euroimmun, Lübeck, Germany) for final confirmation. Sera were collected in endemic regions of southwest region of Kosovo and also in a non-endemic region (Drenas) of Kosovo, also to cover different ecologic conditions.

RESULTS AND DISCUSSIONA total of 932 bovine serum samples were tested for CCHFV-

specific IgG antibodies. The data presented in Table 1 indicate the presence of CCHFV-specific antibodies in 9 districts of Kosovo: 10.2% in Suharekë, 25.25% in Rahovec, 43.65 % in Malishevë,

Figure 1 Kosova map and the study areas.

Table 1: The results obtained from indirect ELISA for detection of CCHFV-specific IgG antibodies in cattle.Region/Location (village)

Serum sample tested (Final result)Animal species Total samples Positive samples Negative Antibody prevalence %

Suharekë Cattle 245 25 220 10.2Rahovec Cattle 198 50 148 25.25Malishevë Cattle 165 72 93 43.65Klinë Cattle 50 4 46 8.0Decan Cattle 77 10 67 12.98Drenas Cattle 49 5 44 10.2Prizren Cattle 48 5 43 10.41Pejë Cattle 50 3 47 6.0Gjakovë Cattle 50 5 45 10Total Cattle 932 179 753 19.2% CI=0.95Abbreviations: CCHFV: Crimean-Congo Hemorrhagic Fever Virus; ELISA: Enzyme-Linked Immunosorbent Assays; CI: Continuous Integration.

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8.0 % in Klinë, 12.98 % in Decan, 10.2% in Drenas, 10.41% in Prizren, 6.0% in Pejë and 10.0% in Gjakovë.

These data strongly indicate the presence and circulation of Crimean-Congo hemorrhagic fever [15]virus among cattle in all different districts of Kosovo. The CCHFV-specific IgG antibody prevalence among cattle in Malisheve was very high (43.64%). Malisheve is already known as a CCHFV hotspot for human infections and many hemorrhagic cases occurred in this district in the past. This correlates well with the high seroprevalence detected in cattle now. One explanation for this accumulation is the high number of Hyalomma ticks in this part of the country [26]. The other municipality with a high prevalence of CCHFV-specific antibodies is Rahovec (25.25 %). The results show that all other areas in Kosovo have lower seroprevalences than Malisheve and Rahovec respectively: Decani 12.99%, Priezreni 10.42%, Drenasi 10.20%, Gjakova 10.0%, Klina 8% and Peja 6%. It is important to emphasize that Prizren is located near the has region in Kukes (Albania). A total of 48 cattle from Prizren were examined and 5 antibody positive sera were found, which gives a seroprevalence of 10.42%. This fits very well to the known seroprevalence in Has-Kukes (16.67 %) [27] and shows that the cross-border circulation of CCHFV virus in the neighboring countries Kosovo and Albania. The results of our study clearly show an overlap between the incidence rates of CCHF in the healthy human population and in animals in Kosovo. From an ecological point of view, the results are consistent with the vegetation and climate present in Kosovo. Seroprevalence is highest in regions with less dense vegetation, where the main occupation is farming and animal breeding. Agriculture in these areas is limited to individual small farms and people commonly get infected by tick bites while working outside. On the other hand, areas of low seroprevalence are mostly forest or mountainous areas at higher altitude. Antibodies can be elicited in humans and animals by high and low virulent CCHF strains. Low, if at all, virulent strains (so-called AP92-like) have been described to circulate in some parts of Greece and Turkey. Hence the detection of CCHFV antibodies in human or animal cohorts should always be interpreted taking into account the presence or absence of human cases. In Kosovo 19.21% of 932 bovines were antibody positive, while in Albania the corresponding national prevalence was much lower (4.74%) [27,28] and intermediate in Macedonia 7% (of 396).

CONCLUSIONThe CCHFV-specific IgG antibody prevalence among cattle in

Malisheve was very high (43.65%), which is known as a CCHFV hotspot for human infections. The other municipality with a high prevalence of CCHFV-specific antibodies in cattle was Rahovec (25.25 %). Both areas are characterized by supporting higher numbers of Hyalomma ticks. The results shown that the other areas in Kosovo illustrate lower seroprevalences: Decani 12.98%, Prizreni 10.41%, Suhareka 10.2%, Drenasi 10.2%, Gjakova 10.0%, Klina 8% and Peja 6%. The results of the here presented study indicate a correlation between the occurrence of clinical CCHF cases in humans and the seroprevalence in cattle in Kosovo.

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Taraku A, Sas MA, Lugaj A, Bizhga B, Berxholi K, et al. (2018) Crimean-Congo Hemorrhagic Fever Virus Infections in Cattle in Kosovo. J Vet Med Res 5(1): 1119.

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