Epidemiology Of Crimean-Congo Hemorrhagic Fever Research Articles

A survey of the tick-borne disease Crimean-Congo hemorrhagic fever in southern Algeria: First serological evidence in the dromedary camel population

Crimean-Congo hemorrhagic fever (CCHF) is a tick-borne viral zoonosis caused by a Nairovirus, Crimean-Congo hemorrhagic fever virus (CCHFV). Despite its wide geographical distribution, the epidemiology of CCHF in northern Africa is incompletely understood and its occurrence in Algeria is virtually unknown. The present survey aimed to determine the prevalence of CCHF antibodies and to identify the potential risk factors associated with CCHFV seropositivity among the one-humped camel (Camelus dromedarius) in southern Algeria. A total of 269 camels selected randomly from slaughterhouses in three wilayas were employed in the study. Sera sampled were tested for the presence of CCHFV-specific IgG antibodies using enzyme-linked immunosorbent assay (ELISA). CCHFV seropositivity was recorded in 255 out of 269 camels accounting for a prevalence rate of 94.8% (95%CI = 92.14–97.45). The seroprevalence by origin was determined to be 97% (193/199) in imported camels and 86% (49/57) in local ones (p > 0.25). Tick presence (OR = 12.35, 95%CI = 1.41–107.43, p < 0.05) was recorded as the only potential risk factor for contracting CCHFV. This study shows for the first time that camels are exposed to CCHFV in Algeria with a significantly high seroprevalence. It also underlines the need for further research to investigate the broader extent of circulating CCHFV in the country, whether in humans, animals, or ticks.

A Review on Crimean-Congo Hemorrhagic Fever Infections in Tunisia.

Crimean-Congo hemorrhagic fever (CCHF) is a zoonotic tick-borne disease, caused by an arbovirus of the genus Orthonairovirus and the family Nairoviridae. Crimean-Congo hemorrhagic fever virus (CCHFV) is widespread in several regions of the world. While the virus is not pathogenic to all susceptible livestock and wild mammals, it can lead to severe hemorrhagic fever in humans. In this review, we compiled published data on CCHFV infections in humans, animals, and ticks in Tunisia. Based on that, we discussed the epidemiology and the distribution patterns of CCHFV infections highlighting the risk factors for this virus in the country. CCHF infection prevalence in humans was estimated to 2.76% (5/181) and 5% (2/38) in Tunisian febrile patients and Tunisian slaughterhouse workers, respectively. Concurrently, seroprevalence in domestic ungulates (sheep, goats, cattle, and dromedaries) ranged from zero to 89.7%, and only one Hyalomma impeltatum tick specimen collected from dromedaries in southern Tunisian was positive for CCHFV by reverse transcriptase-polymerase chain reaction (0.6%; 1/165). As Tunisian studies on CCHFV are geographically scattered and limited due to very small sample sizes, further studies are needed to improve the knowledge on the epidemiology of CCHF in Tunisia.

Clinical and Molecular Epidemiology of Crimean-Congo Hemorrhagic Fever in Humans in Uganda, 2013-2019.

ABSTRACT.Crimean-Congo Hemorrhagic Fever (CCHF) is endemic in Uganda, yet its epidemiology remains largely uncharacterized. To better understand its occurrence within Uganda, case reports of patients hospitalized with CCHF between 2013 and 2019 were reviewed. Further, genome sequences of CCHF-positive RNA obtained during this period were determined for phylogenetic comparisons. We found that a total of 32 cases (75% males; CFR, 31.2%), aged between 9 to 68 years, were reported during the study period. Most cases were detected during July to December of each outbreak year (81.2%; P < 0.01) and were located along the “cattle corridor” (68.7%, P = 0.03). The most common presenting symptoms were fever (93.8%), hemorrhage (81.3%), headache (78.1%), fatigue (68.8%), vomiting (68.8%), and myalgia (65.6%). In five patients for whom hematological data were available, varied abnormalities were observed including thrombocytopenia, leukopenia, anemia, lymphopenia, lymphocytosis, polycythemia, and microcytosis. About 56.3% (P = 0.47) of patients reported tick bites or exposure to livestock as their potential source of infection. Person-to-person transmission was suspected for two cases. Using unbiased metagenomics, we found that the viral S- and L- segments have remained conserved in Africa 2 clade since the 1950s. In contrast, the M segment split into two geographically interspersed clades; one that belongs to Africa 2 and another that is ancestral to Africa 1 and 2. Overall, this data summarizes information on the history and clinical presentation of human CCHF in Uganda. Importantly, it identifies vulnerable populations as well as temporal and geographic regions in Uganda where surveillance and control interventions could be focused.

Overview of crimean-congo hemorrhagic fever 15-year morbidity within 2005-2019 based on ProMED-RUS reports

Background: Russian-language ProMED-mail (ProMED-RUS) reports on emerging infectious diseases in 15 Former Soviet Union (FSU) countries. Among them several regions are endemic for Crimean-Congo hemorrhagic fever (CCHF). Methods & materials: To assess the epidemiology of CCHF in the territory of FSU we reviewed 267 ProMED-RUS reports about CCHF posted from 2005 to 2019. Moderator's comments also were taken in account. Results: According to ProMED-RUS, within 2005-2019 CCHF were registered in Russia (Rostov, Stavropol, Volgograd, Astrakhan regions, republics of Kalmykia, Kabardino-Balkariya, Dagestan, Ingushetiya), Kazakhstan, Georgia, Kyrgyzstan, Uzbekistan and Tajikistan. Between 2005 and 2019, 1,885 cases, including 42 fatalities were recorded in Russia (case fatality rate (CFR) 3%). The highest incidence rate was registered between 2006 and 2008 (200–234 cases). Beginning from 2009, the incidence rate decreased and reached 70-80 cases annually. In 2015, 2016 and 2019 new peaks of CCHF morbidity were recorded (139, 162 and 120 annual cases accordingly).ProMED-RUS started to report about CCHF in the South of Kazakhstan (Jambyl, Kizilorda and Turkestan regions) since 2008, with the highest number of cases (26) in 2009. Between 2010 and 2019 10–20 cases were registered annually with CFR 20-30%.In Tajikistan, ProMED-RUS reported on 5 cases in 2009 including 3 fatalities, CFR was 60%. There are no more available information in Russian language mass media since that time. ProMED-RUS first reported on CCHF cases in Georgia in 2009. In 2010-2012, sporadic cases were registered in the country; since 2013, more than 10 cases were diagnosed annually. CFR in Georgia was more than 30%. In 2019 ProMED-mail first reported on CCHF case in Kyrgyzstan which was imported to Kazakhstan.ProMED-RUS reported also on 13 CCHF cases in Uzbekistan within 2013–2015, including 10 fatal cases, and 2 fatal cases in 2017.Kazakhstan (2009), Tajikistan (2009), and Russia (2011) recorded 3 nosocomial clusters among healthcare workers with 5, 7, and 9 cases respectively. Cluster in Russia was probably related with aerosol-generation procedures. In other countries transmission was connected with unprotected contact with infected blood. Conclusion: ProMED-RUS reports in FSU countries regularly provide useful and prompt information, which allow to monitor epidemiological situation with CCHF in the region.

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

BackgroundCrimean-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).MethodologyA 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 findingsThirty 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).ConclusionsThe 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.

Clinical and molecular epidemiology of Crimean-Congo hemorrhagic fever in Oman.

BackgroundCrimean-Congo hemorrhagic fever (CCHF) is a serious disease with a high fatality rate reported in many countries. The first case of CCHF in Oman was detected in 1995 and serosurveys have suggested widespread infection of humans and livestock throughout the country.MethodologyCases of CCHF reported to the Ministry of Health (MoH) of Oman between 1995 and 2017 were retrospectively reviewed. Diagnosis was confirmed by serology and/or molecular tests in Oman. Stored RNA from recent cases was studied by sequencing the complete open reading frame (ORF) of the viral S segment at Public Health England, enabling phylogenetic comparisons to be made with other S segments of strains obtained from the region.FindingsOf 88 cases of CCHF, 4 were sporadic in 1995 and 1996, then none were detected until 2011. From 2011–2017, incidence has steadily increased and 19 (23.8%) of 80 cases clustered around Eid Al Adha. The median (range) age was 33 (15–68) years and 79 (90%) were male. The major risk for infection was contact with animals and/or butchering in 73/88 (83%) and only one case was related to tick bites alone. Severe cases were over-represented: 64 (72.7%) had a platelet count < 50 x 109/L and 32 (36.4%) died. There was no intrafamilial spread or healthcare-associated infection. The viral S segments from 11 patients presenting in 2013 and 2014 were all grouped in Asia 1 (IV) lineage.ConclusionsCCHF is well-established throughout Oman, with a single strain of virus present for at least 20 years. Most patients are men involved in animal husbandry and butchery. The high mortality suggests that there is substantial under-diagnosis of milder cases. Preventive measures have been introduced to reduce risks of transmission to animal handlers and butchers and to maintain safety in healthcare settings.

Space-time epidemiology of Crimean-Congo hemorrhagic fever (CCHF) in Iran

Iran, as an endemic country of Crimean-Congo hemorrhagic fever (CCHF), has been suffering from severe health issues and substantial economic burdens imposed by the disease. We analyzed monthly and yearly spatial and temporal distributions of CCHF to better understand the epidemiology of the disease in Iran. A cross-sectional survey was performed on 1027 recorded cases between 2000 and 2014. Global Moran’s I analysis was applied to statistically evaluate the spatial pattern of the disease. Additionally, spatial and space-time scan statistics were used to study the presence of possible spatial and space-time hotspots. Global Moran’s I analysis proved that the incidence of the disease is strongly clustered in Iran (p<0.01). Purely spatial scan statistics identified that there were three clusters in the eastern, southern and western parts of the country. Through space-time analysis, we found that the highest incidence of CCHF occurred in the eastern parts of the country between 2006 and 2012. Monthly clusters, which include cities with lower (average) temperatures, had been occurring in relatively short periods. The distribution of CCHF incidence in this country is spatially and temporally clustered. The majority of the clusters emerged during the critical years of 2009 and 2013. Summer is the predominant period for the formation of CCHF clusters.

Crimean-Congo hemorrhagic fever virus in ticks in Turkey: A broad range tick surveillance study

In Turkey, Crimean-Congo hemorrhagic fever (CCHF) outbreaks started in northern regions in 2002. Human cases still continue to increase and the disease spreads in many other provinces of Turkey. The ecological role of the vector tick species occurring in Turkey is not certain exactly. Therefore, we planned a broad range tick study in three different ecological and geographical areas extending from the West Black Sea regions down to the Central Anatolia. The aim of this study was to determine and characterize CCHFV molecularly in feeding-ticks collected from various wild and domestic animals and from humans as well as in questing and unfed ticks. In this study, 4283 tick samples derived from 21 tick species were collected from 76 villages and 10 central districts in total. All tick pools were screened for the presence of CCHFV RNA by two nested RT-PCRs. PCR assays were positive for 27 (3.6%) of 736 pools. CCHFV was detected in Hyalomma marginatum, Dermacentor marginatus, Rhipicephalus bursa, Rhipicephalus turanicus, Hyalomma excavatum and Haemaphysalis parva pools. As a result of the phylogenetic analysis, it was determined that the obtained CCHFV sequences are clustered into Europe 1 clade. CCHFV was detected among ticks obtained from cattle, goats, wild boar, hare, and the ground. The presence of CCHFV in ticks obtained from various domestic and wild hosts and the nature, and thereby the distribution patterns of the virus in different ecological areas were presented in this study. Furthermore, CCHFV was also detected in unusual tick species. Consequently, these results indicate that tick surveillance studies in large-scale and wide varieties contribute to the ecology and epidemiology of CCHF in that region, and can be used as an early-warning system.

Application of Circular ANOVA on Biological Data: Case Study on Crimean-Congo Hemorrhage Fever Cases in Turkey

One of the priorities of Crimean-Congo hemorrhage fever management has been prevention methods. To apply these methods, understanding of transmission mechanisms and influencing factors is crucial. The main driving factor of Crimean-Congo hemorrhage fever time in a year. Plenty of analysis methods, like time series analysis, have been implemented to assess the relationship of Crimean-Congo hemorrhage fever transmission and time of the year. Nonetheless, the majority of analysis methods for the case lacked robustness. Recently, a circular analysis in general and circular ANOVA, in particular, is gaining acceptance by many academicians to assess scenarios that have circularity in their nature. There are few stochastic circular models, but their applicability and tractability are not fully assessed as for their linear counterpart. We examined circular ANOVA models on Crimean-Congo hemorrhage fever data presented by Dr. Fazilet DUYGU (2013) for Turkish public health organization titled “Dunya ve Turkiye’de Kirim-Kongo kanamali atesi epidemiyolojisi” to mean “Crimean-Congo hemorrhagic fever epidemiology in the world and Turkey.” Circular ANOVA method is used to assess the occurrence of the fever in different years. We transformed linear time in months to circular time and convert it to radian form since directional analysis is best suited to radian measures. We used Crimean-Congo hemorrhage fever cases in each month as a dependent linear variable and time in radian as the circular explanatory variable. We have calculated different descriptive statistics for the data and apply circular ANOVA on them and found very sensible methods with few drawbacks.

Spatial cluster analysis of Crimean-Congo hemorrhagic fever virus seroprevalence in humans, Greece

Crimean-Congo hemorrhagic fever (CCHF) is a viral disease transmitted to humans by bite of infected ticks or by direct contact with blood or tissues of viremic patients or livestock. The present cross-sectional meta-analysis study is based on previous data which have shown that the human CCHFV seroprevalence in specific regions of Greece is high (>5%). In the absence of human cases, it has been suggested that a non- or low-pathogenic strain is circulating in the country causing asymptomatic infections. A spatial cluster analysis was performed to assess the geographical variations in CCHFV seropositivity and to identify the risk factors. The overall CCHFV seroprevalence is 3.8%, with significant rate difference between the eastern and western part of the country. Apart the risk factors described in previous studies (age, sex, tick bite, agropastoral activities), the altitude, the land cover type and the transitional woodland/shrub land per person, as well as the number of livestock per person, and specifically the number of goats, sheep and cattle per person, were shown to affect significantly the seroprevalence. Tick studies are needed to identify the circulating strains and unravel the mystery of CCHF epidemiology in Greece.

Molecular epidemiology of Crimean-Congo hemorrhagic fever in Bulgaria--An update.

Crimean-Congo hemorrhagic fever (CCHF) is endemic in Bulgaria. During 2013-2014, 11 confirmed CCHF cases have been reported in the country (seven in 2013 and four in 2014). The present study provides the CCHF molecular epidemiology in Bulgaria based on all currently available S, M, and L RNA segment nucleotide sequences spanning the years 1978-2014. A relatively low genetic difference (0-6%, the maximum seen in the M RNA segment) was seen among the CCHFV sequences suggesting that a slow evolving CCHFV strain belonging to "Europe 1" clade is present in Bulgaria. Although the virus emerged in new foci during the recent years, it is more active in the established endemic foci which seem to offer the most suitable ecosystem and environment. Understanding the CCHF epidemiology and virus evolution is the basis for public health programs and vaccine design.

Current situation of Crimean Congo hemorrhagic fever (CCHF) in Anatolia and Balkan Peninsula

Current situation of Crimean Congo hemorrhagic fever (CCHF) in Anatolia and Balkan Peninsula

Scientific Opinion on the Role of Tick Vectors in the Epidemiology of Crimean-Congo Hemorrhagic Fever and African Swine Fever in Eurasia

The report provides an update on the role of the tick vectors in the epidemiology of African swine fever (ASF) and Crimean and Congo haemorrhagic fever (CCHF) in Eurasia, specifically to review of the geographical distribution of the relevant ticks with presentation of maps of their occurrence in Europe and Mediterranean basin; a description of the factors that define the relevant tick population dynamics and identify possible high risk areas in the EU; an update on the role of tick vectors associated with CCHF and ASF in Eurasia; and reviews available methods for the control of the relevant tick vectors. Data were collected through systematic literature review in a database from which maps of geographic distribution of ticks, CCHF virus and ASF virus were issued. The main vectors for CCHF are Hyalomma spp, Increase in the number of fragmented areas and the degradation of agricultural lands to bush lands are the two main factors in the creation of new foci of CCHF in endemic areas. Movement of livestock and wildlife species, which may carry infected ticks, contributes to the spread of the infection. The Middle East and Balkan countries are the most likely sources of introduction of CCHFV into other European countries. All the Ornithodoros species investigated so far can become infective with ASF virus and are perhaps biological vectors. These ticks are important in maintaining the local foci of the ASFV, but do not play an active role in the geographical spread of the virus. Wild boars have never been found infested by Ornithodoros spp. because wild boars normally do not rest inside protected burrows, but above the ground. There is no single ideal solution to the control of ticks relevant for CCHF or ASF. The integrated control approach is probably the most effective.

The epidemiology of Crimean-Congo hemorrhagic fever in Turkey, 2002–2007

Crimean-Congo hemorrhagic fever (CCHF) is a serious disease caused by the CCHF virus of the Bunyaviridae family. The disease has been reported in 30 countries in Africa, Asia, Eastern Europe, and the Middle East. It has been present in Turkey since 2002. In this study we present and discuss the epidemiological features, clinical and laboratory findings, treatment, and outcome of cases diagnosed with CCHF between 2002 and 2007 from the surveillance results of the Turkish Ministry of Health (MoH). According to the surveillance system of the MoH, data for patients with clinical, laboratory, and epidemiological findings compatible with CCHF are recorded on case reporting forms. These forms are submitted to the General Directorate of Primary Health Care of the MoH by the city health directorates. All the surveillance data regarding CCHF were recorded on a database (SSPS 11.0) established in the Communicable Diseases Department of the MoH. According to the surveillance reports of the Turkish MoH, between 2002 and 2007, 1820 CCHF cases occurred (150 in 2002-2003, 249 in 2004, 266 in 2005, 438 in 2006, and 717 in 2007). The crude fatality rate was calculated to be 5% (92/1820). Two thirds of the CCHF cases were reported from five cities located in the Mid-Eastern Anatolia region; 69.4% of the cases were from rural areas. The male to female ratio was 1.13:1. Of all the reported cases, 68.9% had a history of tick-bite or tick contact and 84.1% were seen in the months of May, June, and July. Of 1820 CCHF cases, three (0.16%) were nosocomial infections. CCHF appears to be a seasonal problem in the Mid-Eastern Anatolia region of Turkey. The possible risk factors for transmission and the clinical and laboratory findings of patients with a diagnosis of CCHF were found to be similar to those reported in the literature. The mean fatality rate for Turkey is lower than the rate reported for other series from other parts of the world.

Dynamics of African tick (Acari: Ixodoidea) populations in a natural Crimean-Congo hemorrhagic fever focus.

A study of ticks collected from large and small mammals and from vegetation in an area where Crimean-Congo hemorrhagic fever (CCHF) virus was found was carried out over 3 yr. Three two-host species of ticks, Hyalomma marginatum rufipes Koch, Hyalomma truncatum Koch, and Rhipicephalus evertsi evertsi (Neumann), were abundant; and three other species, Amblyomma marmoreum Koch, Margaropus winthemi Karsch, and Argas, undescribed sp., were less frequently encountered. Immatures of H. m. rufipes and H. truncatum showed two peaks of activity, one in July and one in November; adults were most active during December, January, and February. A similar pattern of seasonal activity was found for larvae and nymphs of R. e. evertsi, which showed peaks in their occurrence in May and in October/November. H. m. rufipes adults were more common on eland and Burchell's zebra, but H. truncatum preferred black wildebeest. Immature stages of these species also showed host preference. H. truncatum was very common on rodents and hares and absent from guinea fowl; H. m. rufipes was found on guinea fowl and also on hares, but not on rodents. Seasonal activity of ticks, the hosts with which they are associated, and their role in the epidemiology of CCHF are discussed.