The seroprevalence of Crimean-Congo haemorrhagic fever among inhabitants living in the endemic regions of Western Anatolia

Seroprevalence of Crimean Congo Hemorrhagic Fever Virus in Occupational Settings: Systematic Review and Meta-Analysis

Crimean Congo Hemorrhagic Fever (CCHF) Virus can cause a serious human disease, with the case fatality ratio previously estimated to be 30-40%. Our study summarized seroprevalence data from occupational settings, focusing on the following occupational groups: animal handlers, abattoir workers, farmers, healthcare workers, veterinarians, rangers, and hunters. Systematic research was performed on three databases (PubMed, EMBASE, MedRxiv), and all studies reporting seroprevalence rates (IgG-positive status) for CCHF virus were retrieved and their results were reported, summarized, and compared. We identified a total of 33 articles, including a total of 20,195 samples, i.e., 13,197 workers from index occupational groups and 6998 individuals from the general population. Pooled seroprevalence rates ranged from 4.751% (95% confidence intervals (95% CI) 1.834 to 11.702) among animal handlers, to 3.403% (95% CI 2.44 to 3.932) for farmers, 2.737% (95% CI 0.896 to 8.054) among rangers and hunters, 1.900% (95% CI 0.738 to 4.808) for abattoir workers, and 0.644% (95% CI 0.223-1.849) for healthcare workers, with the lowest estimate found in veterinarians (0.283%, 95% CI 0.040-1.977). Seroprevalence rates for abattoir workers (odds ratio (OR) 4.198, 95% CI 1.060-16.464), animal handlers (OR 2.399, 95% CI 1.318-4.369), and farmers (OR 2.280, 95% CI 1.419 to 3.662) largely exceeded the official notification rates for CCHF in the general population. CCHF is reasonably underreported, and pooled estimates stress the importance of improving the adherence to personal protective equipment use and appropriate preventive habits.

Determination of Seroprevalence and Risk Factors of Crimean-Congo Haemorrhagic Fever (CCHF) in the Endemic Region in Turkey: A Population-Based Cross-Sectional Study

Objectives

Turkey is one of the countries that has the most cases of CCHF in recent years among the endemic countries. The disease also poses an important health threat with high mortality rate. The aim of the study was to determine the seroprevalence and risk factors of CCHF in adults aged ≥20 years in Tokat in the endemic region, Turkey.

Methods

In this population-based cross-sectional study, a total of 85 Family Medicine Units (FMUs), from over 170 in Tokat, were randomly selected using 50% sampling. The sample size was determined among the subjects aged ≥20 who registered with the FMUs, due to gender, age group, and the urban/rural population size of Tokat using the stratified cluster sampling method. Subjects were invited to the FMUs. A questionnaire was performed face to face. The blood samples were taken, and anti-CCHFV IgG antibodies were measured with ELISA method.

Results

1272 (54.9%) out of 2319 participants were female, and the mean age was 47.3 ± 15.3. Anti-CCHFV IgG seropositivity was 5.6% (n = 130). Seropositivity rates in terms of adjusted odds ratios (AOR) were higher 2.53 times (95% CI: 1.57–4.08; p=0.001) in males; 4.05 (95% CI: 2.14–7.65; p < 0.001) in age group ≥65; 0.33 (95% CI: 0.14–0.76; p < 0.001) in graduates of high school and above; 0.71 (95%CI: 0.33–1.52; p < 0.001) in ones with good income; 1.84 (95%CI: 1.18–2.86; p < 0.001) in farmers; 1.64 (95% CI: 1.04–2.27; p < 0.001) in people dealing with animal husbandry; and 1.02 (95% CI: 1.03–2.29; p < 0.001) in those with history of tick contact.

Conclusions

CCHF seroprevalence is still a common public health problem in Tokat, Turkey. Male gender, advanced age group, low-educated, low-income, farmers, animal husbandry, and history of tick contact were found to be risk factors for CCHF. The importance of this kind of community-based studies to identify the seroprevalence in regional and national level increases even more.

High prevalence and different genotypes of Crimean-Congo hemorrhagic fever virus genome in questing unfed adult Hyalomma marginatum in Thrace, Turkey

Crimean-Congo hemorrhagic fever (CCHF) is a tick-borne viral disease in the old continents, in many countries south of the 50 °North Parallel. The agent is known to be the most prevalent and major cause of severe and fatal human hemorrhagic diseases among the tick-borne viruses, and is the second most widespread of all medically critical arboviruses following dengue. Members of the Hyalomma genus are mainly involved in the natural transmission of the CCHF virus (CCHFV); of those, H. marginatum is known to be the primary vector of the disease in the Western Palaearctic. In general, epidemiological studies have been based on serological detections in the hosts and/or virus screening of ticks collected from the hosts. To the best of our knowledge, only a few studies have been carried out to screen the virus in unfed, questing field ticks. Nevertheless, detection of the virus in questing ticks is known to be a crucial parameter to determine the possible vector roles of the ticks and to understand the ecological dynamics of related diseases. In this study, 200 (75 males,125 females) questing H. marginatum adults collected from the field in nine villages in Thrace, located in the European part of Turkey, were screened individually for CCHFV using nested PCR. As a result, 103 (51.5 %) ticks were determined as positive with various strains of CCHFV. High positivity in questing vectors in a region where a significantly lower number of human cases have been encountered suggests that there should be some region-specific drivers that are effective in the natural dynamics of the disease. Detailed etiological and epidemiological studies are needed to reveal the possible reason for this unexpected discrepancy.

Towards a Sustainable One Health Approach to Crimean-Congo Hemorrhagic Fever Prevention: Focus Areas and Gaps in Knowledge

Crimean–Congo hemorrhagic fever virus (CCHFV) infection is identified in the 2018 World Health Organization Research and Development Blueprint and the National Institute of Allergy and Infectious Diseases (NIH/NIAID) priority A list due to its high risk to public health and national security. Tick-borne CCHFV is widespread, found in Europe, Asia, Africa, the Middle East, and the Indian subcontinent. It circulates between ticks and several vertebrate hosts without causing overt disease, and thus can be present in areas without being noticed by the public. As a result, the potential for zoonotic spillover from ticks and animals to humans is high. In contrast to other emerging viruses, human-to-human transmission of CCHFV is typically limited; therefore, prevention of spillover events should be prioritized when considering countermeasures. Several factors in the transmission dynamics of CCHFV, including a complex transmission cycle that involves both ticks and vertebrate hosts, lend themselves to a One Health approach for the prevention and control of the disease that are often overlooked by current strategies. Here, we examine critical focus areas to help mitigate CCHFV spillover, including surveillance, risk assessment, and risk reduction strategies concentrated on humans, animals, and ticks; highlight gaps in knowledge; and discuss considerations for a more sustainable One Health approach to disease control.

Seroprevalence of Crimean-Congo hemorrhagic fever in humans in the World Health Organization European region: A systematic review

BACKGROUND

Crimean-Congo hemorrhagic fever (CCHF) is an emerging infectious disease caused by a Nairovirus. CCHF is a tick-borne disease that is predominantly associated with Hyalomma ticks and have a widespread distribution in Africa, Asia and Europe. CCHF usually presents as a subclinical disease, but in some cases, it may present as a hemorrhagic fever with a high mortality rate. This systematic review of the literature was performed to identify the available evidence on the prevalence of CCHF in the European Region of the World Health Organization, based on seroprevalence (IgG antibodies).

METHODOLOGY

A systematic review was performed following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement protocol. PubMed, Embase, and the Web of Science were used for the search (up to January 31, 2019), combining the following MeSH terms: ["Crimean-Congo haemorrhagic fever" OR "Crimean-Congo hemorrhagic fever virus" OR "Congo-Crimea" OR "Crimea-Congo"] AND ["Europe"] AND ["epidemiology" OR "seroprevalence"]. The abstracts were screened. Subsequently, full-text articles were selected and reviewed based on the PICOS (Population-Intervention-Comparison-Outcomes-Study type) criteria by two independent reviewers for inclusion in the final analysis. The data were qualitatively synthesized without quantitative pooling due to the heterogeneity in the study populations and methodologies.

PRINCIPAL FINDINGS

Thirty articles (9 from western Europe, 18 from central Europe and 3 from eastern Europe) were included in the analysis. All articles were cross-sectional studies (descriptive studies).

CONCLUSIONS

The highest seroprevalence of CCHF is found in central and eastern European countries. Southern and western Europe countries, such as Greece and Spain, have low levels of endemicity, but the spread of the infection, which is associated with climate change, is a possibility that we should keep in mind. Further studies, especially larger seroprevalence studies in humans and animals, are needed to establish the current status of the CCHF epidemiology and to generate standardized guidelines for action in the region.

Crimean-Congo hemorrhagic fever (CCHF) seroprevalence: A systematic review and meta-analysis

Crimean-Congo haemorrhagic fever (CCHF) is the most widespread, tick-borne viral disease affecting humans and therefore this paper performed a meta-analysis to highlight seroprevalence features of CCHF in a global context. After a preliminary review of the 396 papers representing areas throughout the world, 206 were selected for detailed meta-analysis. In general the total means of CCHF seroprevalence were, respectively 4.7 and 24.6% for humans and animals; and 17.1, 18.9, 24.3, 29.3 and 27.1% for camels, cattle, goats, sheep and livestock. Statistical analysis revealed a significant difference in seroprevalence between humans and camels (P = 0.043), cattle (P = 0.010), goats (P = 0.015), sheep (P = 0.005) and livestock (P = 0.017). Regionally, there also was a difference between humans, and goats (P = 0.0001), sheep (P = 0.007) and livestock (P = 0.002). Globally, CCHF seroprevalence in at-risk professionals was 7.5 fold greater than in normal humans, while CCHF seroprevalence was 5 fold greater in animals, camels, cattle, goats, sheep and livestock than normal humans. Animal contact, animal husbandry, farming, tick bite history and secretion exposure were the most frequently reported CCHF seropositivity risk factors. This study serves as an important resource for epidemiological discussions related to CCHF and CCHF seroprevalence features, providing specific information in understanding human and animal mean and trend CCHF seroprevalence for different regions of the world and on an aggregate global scale; seroprevalence in at-risk professionals; and total mean and trend CCHF seropositivity involving risk factors.

Serological Investigation of Occupational Exposure to Zoonotic Crimean-Congo Hemorrhagic Fever Infection

Objective

Crimean-Congo hemorrhagic fever (CCHF) is an acute and highly fatal disease. In this study, our aim was to compare and evaluate the prevalence of CCHF virus (CCHFV) antibody among occupational high-risk groups by using the enzyme-linked immunosorbent assay and draw attention to the occupational groups that are at high risk for CCHF infection in an endemic region for this zoonotic infection in Erzurum, Turkey.

Materials and Methods

The antibody levels against CCHFV were surveyed among slaughterhouse workers, animal breeders, and veterinarians. The study population was composed of 72 participants having direct contact with animals and 19 blood donors who were not in direct contact with animals.

Results

The overall rate of CCHF immunoglobulin G positivity in risk groups was found to be 6.94% (5/72). CCHFV antibodies were found in 4 (12.5%) individuals of the animal breeder group. This ratio was considered significantly higher compared with the healthy control group. CCHFV antibodies were found in only one person (4.0%) who was an abattoir worker. In the veterinarian group, all people were found negative.

Conclusion

In our study, the variables showing important associations with the prevalence of anti-CCHFV antibodies were livestock breeding, rural areas, and age. It was concluded that our region is endemic with regard to CCHF infection and persons who had direct contact with animals are at high risk. Thus, these participants must take necessary measures to protect themselves from CCHF and should be trained by health authorities.

Evaluation of Crimean-Congo hemorrhagic fever suspected cases admitted to a secondary care hospital in Kastamonu, Turkey between 2014-2017

Background

Crimean-Congo hemorrhagic fever (CCHF) is an endemic zoonosis in Kastamonu, Turkey. Clinical and laboratory findings may not be specific in the early phase of the disease, hence bringing a challenge to the clinician.

Objective

We aimed to distinguish CCHF cases among all suspected cases by comparing them with non-CCHF cases with respect to characteristics during admission.

Methods

Cases with a presumptive diagnosis of CCHF at a secondary care hospital in Kastamonu in between 2014–2017 were evaluated, retrospectively. CCHF and non-CCHF cases were compared with respect to their clinical, laboratory and epidemiological characteristics during admission.

Results

Among 76 suspected patients, CCHF was found in 46.1% of them. Four-year fatality rate was 9.6% in CCHF cases. The frequency of headache, nausea/vomiting, leukopenia, thrombocytopenia less than 50x109/L, AST-ALT and LDH elevation, tick bites and contact with blood or body fluids of animals in CCHF cases were significantly higher than in non-CCHF cases (p<0.05).

Conclusion

Headache and nausea/vomiting accompanied with leukopenia, thrombocytopenia less than 50x109/L, AST-ALT and LDH elevations raise the possibility of CCHF in endemic regions especially when there is a history of tick bite and contact with blood or body fluids of animals.

Country-wide seroprevalence studies on Crimean-Congo hemorrhagic fever and hantavirus infections in general population of Bulgaria

Crimean-Congo hemorrhagic fever (CCHF) and hantavirus infections are the two viral hemorrhagic fevers spread in Europe. To test actual circulation of CCHF virus (CCHFV) and hantaviruses in Bulgaria, we conducted country-wide seroepidemiological studies. Serum samples were collected prospectively from 1500 residents of all 28 districts in Bulgaria. CCHFV seroprevalence of 3.7% was revealed. Anamnesis for tick bites, contact with livestock, age over 40 years and residency in Haskovo district were found as risk factors. The highest CCHFV seroprevalence was observed in the known endemic districts in southeastern Bulgaria: Haskovo (28%) and Yambol (12%). Reactive samples were found in residents of 20 of the 28 districts in Bulgaria. In comparison with the previous studies, the data presented indicate that CCHFV increased substantially its circulation in the endemic regions and was introduced in many new areas. Hantavirus seroprevalence was based on results of the immunoblot and estimated as 3.1%. Surprisingly, contrary to all available data, Puumala virus seroprevalence rate was 2.3% versus 0.8% of Dobrava-Belgrade virus. Evidence for hantavirus IgG seropositivity was found in residents of 23 of the 28 districts in the country. The first hantavirus seroprevalence study in Bulgaria showed that Puumala virus is probably more wide-spread in the country than Dobrava-Belgrade virus.

Seroprevalence of Crimean-Congo Hemorrhagic Fever in Turkey's Van Province

Crimean-Congo hemorrhagic fever (CCHF) is an endemic tick-borne viral disease that affects both animals and humans. This study aims to determine the seroprevalence of CCHF in Turkey's Van province using analysis of blood samples obtained from people living in the region. Blood specimens were taken from healthy subjects living in Van province and some of the surrounding villages between January and July 2012. Blood samples were initially tested using a CCHF virus (CCHFV) IgM IgG kit for anti-CCHFV IgG, followed by anti-CCHFV IgM determination of any IgG positive blood samples. IgM-positive specimens were re-confirmed using real-time polymerase chain reaction (qPCR). One hundred and 7 men and 261 women were included in the study. Fifty-three blood specimens (14.4%) were anti-CCHFV IgG positive, and 2 of these were anti-CCHFV IgM positive. Two blood samples with anti-CCHFV IgM seropositivity tested negative using qPCR, indicating chronic infections. Locality, sex, and a history of tick bites did not significantly affect anti-CCHFV IgG seropositivity. Although the incidence of anti-CCHFV IgG in blood specimens was 14.4%, no deaths have yet been reported in Turkey's Van province. It is imperative that clinical CCHFV tests be implemented for people at high risk of developing CCHFV-related complications.

Seroprevalence of Crimean-Congo Hemorrhagic Fever Virus in Erzincan Province, Turkey, Relationship with Geographic Features and Risk Factors

To determine the seroprevalence and risk factors associated with Crimean-Congo hemorrhagic fever virus (CCHFV) in residents of Erzincan, Turkey. Although CCHFV is endemic in Erzincan, this is the first study to evaluate its seroprevalence in this region. This study included a total of 372 subjects, 174 of whom had been exposed to or bitten by ticks, 145 of whom worked with livestock, and 53 of whom resided in the city and did not have exposure to livestock. Data on CCHFV IgG and IgM antibodies were extracted from serum samples collected from all subjects using an ELISA. All samples were tested for CCHFV IgG and CCHFV IgM. Only IgM-positive samples were processed for detection of viral RNA through RT-PCR. Using seropositive cases only, we performed spatial analyses to evaluate correlations between seroprevalence and geographic location (i.e., proximity to rivers, altitude, and slope angle of land). In this study, 14.0% (52/322) of the total subjects were positive for CCHFV IgG. Seven of the individuals were positive both for CCHFV IgG and CCHFV IgM. Of these seven, only one sample tested positive for CCHFV RNA. Individuals who worked with livestock in the rural areas and had a history of tick exposure were statistically more likely to test positive for CCHFV IgG than individuals from the city and not exposed to ticks (p < 0.05). Seroprevalence was affected by geographic characteristics, including distance to rivers, altitude, and slope angle of land. We observed a high seroprevalence of CCHFV in Erzincan, which is similar to that observed in other endemic regions of Turkey. CCHFV seroprevalence rates are found to be quite high in the people who live in the sloping fields at certain heights and where there are a lot of rivers and streams.

The geographic distribution of cases of Crimean-Congo hemorrhagic fever: Kastamonu, Turkey

The purpose of this study was to analyze the epidemiological characteristics of cases diagnosed with Crimean-Congo Hemorrhagic Fever (CCHF) with the help of Geographic Information Systems (GIS) and to establish an epidemiological risk map. Data for 434 cases diagnosed with CCHF between 01.01.2004 and 31.12.2013 were subjected to statistical analysis SPSS 13.0 software. A digital map of Kastamonu was transferred onto ArcGIS 10.0 software in order to establish a risk map for CCHF. The highest cumulative incidence of CCHF is 41.29/10,000, and in people living at altitudes of 1001-1200 meters. ROC analysis of altitudes above sea level of residences with CCHF cases revealed an area under the curve of 74.5% (95% CI: 0.72-0.76, p<0.05). At a cut-off point of 836.5 meters, sensitivity was 0.74 and specificity 0.76. Cumulative incidence of CCHF was significantly positively correlated with number of animals per head (r=0.76) and area of agricultural land per head (r=0.59) (p<0.05). No significant correlation was determined between cumulative incidence and forested area percentages. This study reveals that both men and women living at more than 836.5 meters above sea level and working in agriculture and animal husbandry are at risk of CCHF between May and July. Detailed examination of the ecology of vector ticks is now needed in order to fully determine the epidemiology of the disease.

Evaluation of cases with a preliminary diagnosis of Crimean- Congo hemorrhagic fever and comparison of characteristics in patients admitted to a secondary care hospital in Kastamonu, Turkey

BACKGROUND

Crimean-Congo hemorrhagic fever (CCHF) is an endemic disease in Turkey. The clinical presentation and laboratory findings are not specific especially in cases without hemorrhagic findings.

OBJECTIVE

We aimed to evaluate CCHF cases and compare them with non-CCHF cases in terms of their characteristics during admission.

METHODS

Cases with a preliminary diagnosis of CCHF at a secondary care hospital in Kastamonu in 2013 were evaluated, retrospectively. Cases testing RNA/IgM positive were considered as CCHF. Cases testing both RNA and IgM negative were considered as non-CCHF. The two groups were then compared in terms of their clinical, laboratory and epidemiological characteristics during admission.

RESULTS

A total of 41 cases were tested and CCHF was found in 46.3% of cases. Fatality was 5.3% in CCHF cases. The frequency of tick bites and CK elevation in CCHF cases was significantly higher than non-CCHF cases (p<0.05). There were no significant differences between the two groups regarding other characteristics (p>0.05).

CONCLUSIONS

In cases with a preliminary diagnosis of CCHF, especially in cases without a history of tick bite and with normal CK levels during admission, performing tests for the differential diagnosis may be advisable without waiting for the results of tests for CCHF.

Prevalence of Crimean-Congo hemorrhagic fever virus in healthy population, livestock and ticks in Kosovo

Crimean-Congo hemorrhagic fever (CCHF) is an acute, tick borne disease often associated with hemorrhagic presentations and high case fatality rate. Kosovo is a highly endemic area for CCHF, with a significant case fatality rate. The aim of our study was to determine the prevalence of CCHF in Kosovo. We tested 1105 serum samples from healthy population in both endemic and non-endemic areas in the country. Our results revealed a seroprevalence of 4.0% (range 0-9.3%) which is comparable to the seroprevalence in other countries. We show that seroprevalence is correlated to the disease incidence in each studied municipality. We also tested 401 animal sera (353 cow, 30 sheep, 10 goat and 8 chicken) in four endemic municipalities in Kosovo. We detected specific antibodies in all animals except in chicken. Seroprevalence in cows is comparable to other endemic areas and correlates to the seroprevalence in humans. No CCHF RNA could be detected in 105 tick samples obtained in 2012 and 2013. Sequencing of CCHFV positive ticks from 2001 revealed that the virus is most closely related to viral strains that were detected in CCHF patients from Kosovo. Results suggest that mild CCHF cases are most probably underdiagnosed and consequently that the burden of disease is higher than reported. Our study provides key information for CCHF surveillance and raises awareness for possible imported cases in CCHF non-endemic countries.

Clinical symptoms and laboratory findings supporting early diagnosis of Crimean-Congo hemorrhagic fever in Iran

Crimean-Congo hemorrhagic fever (CCHF) is a zoonotic disease, which is usually transmitted to humans by tick bites or contact with blood or other infected tissues of livestock. Patients suffering from CCHF demonstrate an extensive spectrum of clinical symptoms. As it can take considerable time from suspecting the disease in hospital until reaching a definitive diagnosis in the laboratory, understanding the clinical symptoms and laboratory findings of CCHF patients is of paramount importance for clinicians. The data were collected from patients who were referred to the Laboratory of Arboviruses and Viral Hemorrhagic Fevers at the Pasteur institute of Iran with a primary diagnosis of CCHF between 1999 and 2012 and were assessed by molecular and serologic tests. Referred patients were divided into two groups: patients with a CCHF positive result and patients with a CCHF negative result. The laboratory and clinical findings of these two groups were then compared. Two-thousand five hundred thirty-six probable cases of CCHF were referred to the laboratory, of which 871 cases (34.3%) were confirmed to be CCHF. Contact with infected humans and animals increased the CCHF infection risk (P < 0.001). A tick bite was not a risk factor. Fever; bleeding, vomiting, leucopoenia, thrombocytopenia, and increases in alanine transaminase (ALT) and aspartate transaminase (AST) levels were also indicative of CCHF infection. Accurate and speedy diagnosis of CCHF and appropriate treatment play an important role in patient survival and the application of the findings of this study can prove helpful as a key for early diagnosis.

Seroprevalence and risk factors of Crimean-Congo hemorrhagic fever in selected seven provinces in Turkey

Turkey has been one of the most endemic regions since 2002, when Crimean-Congo hemorrhagic fever emerged worldwide. The aim of the present study was to estimate the seroprevelance of CCHF virus in humans who reside in rural and urban areas of known endemic and nonendemic selected provinces of Turkey by using commercial ELISA kit. CCHFV IgG antibodies were detected in 2.3% of the population. The most important risk factors for CCHF seropositivity, were older age, male gender, illiterate, farmer, animal husbandry, living in rural residence in adobe houses, and a previous tick bite history.

Crimean-Congo hemorrhagic fever: seroprevalence and risk factors among humans in Achaia, western Greece

BACKGROUND

The Crimean-Congo hemorrhagic fever virus (CCHFV) presents a wide distribution, with the Balkan Peninsula being among the endemic regions. To date, only one CCHF case has been reported in Greece; however, based on seroprevalence data, there is evidence that CCHFV circulates in the country. Achaia is a prefecture in western Greece that has not previously been studied for CCHFV.

OBJECTIVES

The aim of this study was to estimate the seroprevalence of CCHFV in humans in Achaia Prefecture, Greece, and to assess possible factors playing a role in seropositivity.

METHODS

A total of 207 serum samples from people of all age groups, from both urban and rural areas, were prospectively collected and tested for IgG antibodies against CCHFV.

RESULTS

The overall seroprevalence was 3.4%, with significant differences among municipalities. An agro-pastoral occupation, contact with sheep and goats, former tick bite, increasing age, and living at an altitude of ≥400 m, on specific land cover types, were significantly associated with CCHFV seropositivity.

CONCLUSIONS

A relatively high seroprevalence was detected in a previously unstudied region of Greece, where CCHFV infection seems to occur mainly through tick bites. Further investigations are needed to identify the circulating CCHFV strains in Greece, in order to gain a better understanding of CCHFV ecology and epidemiology in the country.

Crimean-Congo hemorrhagic fever: an overview

Crimean-Congo hemorrhagic fever (CCHF) is a zoonotic viral infection that is a serious threat to humans. The disease is widely distributed in Africa, Asia, and Europe and has developed into a serious public health concern. Humans become infected through the bites of ticks, by contact with a patient with CCHF, or by contact with blood or tissues from viremic livestock. Microvascular instability and impaired hemostasis are the hallmarks of the infection. Infection in human begins with nonspecific febrile symptoms, but may progress to a serious hemorrhagic syndrome with high mortality rates. Enzyme-linked immunoassay (ELISA) and polymerase chain reaction (PCR) are the most used and specific tests for the diagnosis. The mainstay of treatment is supportive. Although definitive studies are not available, ribavirin is suggested to be effective especially at the earlier phase of the infection. Uses of universal protective measures are the best way to avoid the infection. In this review, all aspects of CCHF are overviewed in light of the current literature.

Recommended precaution procedures protect healthcare workers from Crimean-Congo hemorrhagic fever virus

OBJECTIVES

The Crimean-Congo hemorrhagic fever (CCHF) virus can spread from person to person and may cause nosocomial outbreaks among healthcare workers (HCWs). The US Centers for Disease Control and Prevention have recommended the use of personal protective equipment (PPE). We investigated the compliance of HCWs with PPE usage during the follow-up of patients, and also the number of risky contacts that occurred between patients and HCWs. We also aimed to determine the seroprevalence of CCHF virus in HCWs.

METHODS

This study was conducted at Cumhuriyet University Education and Research Hospital, a medical center located in a highly endemic area for CCHF where a total of 1284 confirmed CCHF patients were followed-up between 2002 and 2012. All HCWs who were at risk of CCHF virus contact and infection were included in the study. The compliance of the HCWs with PPE usage and the number of contacts that had occurred were recorded. HCW serum samples were analyzed for CCHF virus IgM and IgG by ELISA.

RESULTS

The total rates of PPE usage were 93.7% for gowns, 77.4% for gloves, and 38.9% for masks; the highest compliance was detected in the infectious diseases ward: 100%, 88.6%, and 82.9%, respectively. A total of four HCWs had a history of high-risk contact with contaminated material (two percutaneous exposure and two mucosal contacts), but the number of low-risk contacts was quite high. The total seroprevalence rate was only 0.53%.

CONCLUSIONS

Although the HCWs at our medical center have dealt with an extremely high number of CCHF patients during the last decade, the total seropositivity for CCHFV IgG was only 0.53%. This low rate may be a result of high compliance with PPE usage and also regular education programs.

The seroprevalance of Crimean-Congo haemorrhagic fever in people living in the same environment with Crimean-Congo haemorrhagic fever patients in an endemic region in Turkey

Crimean-Congo haemorrhagic fever (CCHF) is endemic in Turkey, and since 2004 many cases have been reported from different regions of Turkey. There are limited data about the seroprevalence of the disease in household members of patients or persons sharing the same environment. We evaluated seroprevalence of CCHF in the immediate neighbourhood and in household members of patients living in the same environment as confirmed cases of CCHF in an endemic area of Turkey. A total of 625 healthy subjects [mean (s.d.) age: 42·3 (18·4) years, 58·7% females] without a past history of CCHF infection included in this case-control, retrospective study were evaluated in terms of sociodemographic characteristics, risk factors for CCHF via a study questionnaire, while serum analysis for CCHF virus (CCHFV) IgG antibodies was performed by ELISA. Anti-CCHFV IgG antibodies were positive in 85 (13·6%) participants. None of the seropositive individuals had a history of symptomatic infection. Regression analysis revealed that animal husbandry [odds ratio (OR) 1·84, 95% confidence interval (CI) 1·09-3·11], contact with animals (OR 2·31, 95% CI 1·08-5·10), contact with ticks (OR 3·45, 95% CI 1·87-6·46), removing ticks from animals by hand (OR 2·48, 95% CI 1·48-4·18) and living in a rural area (OR 4·05, 95% CI 1·65-10·56) were associated with increased odds of having IgG seropositivity, while being a household member of a patient with prior CCHF infection had no influence on seropositivity rates. This result also supports the idea that CCHF is not transmitted person-to-person by the airborne route.

Epidemiologic features and risk factors of Crimean-Congo hemorrhagic fever in Samsun province, Turkey

Background

Crimean–Congo hemorrhagic fever (CCHF) is a tick-borne infectious disease that has a considerable mortality risk and is a challenge for the population of endemic rural areas and health care workers. This study investigated the epidemiologic features and main risk factors of CCHF in Samsun Province, Turkey, using CCHF cases diagnosed from 2007 to 2011 recorded by the Samsun Provincial Health Directorate.

Methods

In the study area, 126 cases were evaluated statistically and spatially. Minitab 16 software was used for statistical analysis of the data, and ArcGIS 9.3 software was used for spatial analysis.

Results

Among those who received a diagnosis of CCHF, 69 (54.7%) were male, 57 (45.3%) were female, 114 (90.5%) were discharged, and 12 (9.5%) died. A total of 112 of the 126 (88.9%) cases occurred at an altitude higher than 600 m. In addition, 84.1% of cases were reported during May through July, which are the busiest months for those working in the agriculture and animal husbandry sectors.

Conclusions

CCHF causes severe disease and has a high mortality rate (about 10% in Turkey). Early diagnosis of CCHF can be improved by periodic education of people at high risk, ie, men and women working in agriculture and animal husbandry in rural areas and those working in health care.