Crimean-Congo Hemorrhagic Fever Research Articles

Crimean-Congo haemorrhagic fever among healthcare workers in Iran 2000–2023, a report of National Reference Laboratory

Crimean-Congo haemorrhagic fever among healthcare workers in Iran 2000–2023, a report of National Reference Laboratory

Further evidence of antibodies against Crimean-Congo haemorrhagic fever virus in different livestock species in Nigeria

Further evidence of antibodies against Crimean-Congo haemorrhagic fever virus in different livestock species in Nigeria

Acute promyelocytic leukemia as a differential diagnosis of Crimean-Congo hemorrhagic fever

Acute promyelocytic leukemia as a differential diagnosis of Crimean-Congo hemorrhagic fever

Vectorial dynamics underpinning current and future tick-borne virus emergence in Europe.

Tick-borne diseases pose a growing threat to human and animal health in Europe, with tick-borne encephalitis virus (TBEV) and Crimean-Congo haemorrhagic fever virus (CCHFV), vectored by Ixodes ricinus and Hyalomma marginatum, respectively, emerging as primary public health concerns. The ability of ticks to transmit pathogens to multiple hosts and maintain infections across life stages makes them highly efficient vectors. However, many aspects of tick ecology and vectorial capacity remain understudied. This review examines key factors contributing to the vectorial competence of European ticks and their associated viruses. We first explore the influence of climate change on vector and disease ecology, using TBEV and CCHFV as case studies. We then analyse the role of the tick antiviral response in shaping vector competence. By integrating these elements, this review aims to enhance our understanding of tick-borne viral diseases and support the development of public health strategies, particularly through the One Health framework, to mitigate their impact in Europe.

Inflammation associated with monocyte/macrophage activation and recruitment corresponds with lethal outcome in a mouse model of Crimean-Congo hemorrhagic fever

Crimean-Congo hemorrhagic fever virus (CCHFV) causes human disease ranging from subclinical to a fatal hemorrhagic syndrome. Determinants of CCHF pathogenesis are largely unknown and animal models that recapitulate human disease are limited. A recently described mouse model uses a monoclonal antibody (mAb 5A3) targeting the interferon (IFN) alpha/beta receptor to suppress type I IFN responses, making animals transiently susceptible to infection. To advance utility of this model, we investigated effects of challenge route, timing of 5A3 delivery, mouse sex and age, and virus strain on clinical course and outcome. C57BL/6J mice received mAb 5A3 -1, 0, or -1/+1 days post-infection (dpi). Subsets were challenged with CCHFV strain Turkey04 or IbAr10200 subcutaneously or intraperitoneally, and serially euthanized 3- and 7-dpi, when meeting euthanasia criteria or at study completion (14 dpi). CCHFV-IbAr10200-infected mice almost uniformly succumbed to infection, whereas CCHFV-Turkey04-infected mice transiently lost weight but survived. These results were consistent regardless of mAb timing or route of challenge. Viral replication and dissemination were comparable between the two strains at 3 dpi. However, in the plasma and livers of non-survivors, expression of proinflammatory cytokines/chemokines that correspond with macrophage activation and recruitment were significantly elevated. Lethal disease was also associated with elevated levels of macrophage activation marker CD163 in plasma. Further, mouse macrophages were more permissive to IbAr1200 infection in vitro, suggesting tropism for these cells may influence pathogenesis. Our data suggest that early inflammation may be a critical determinant of CCHF outcome and therapeutics to control inflammation may be worthwhile targets for future investigation.

Metagenomic Nanopore Sequencing of Tickborne Pathogens, Mongolia.

We performed nanopore-based metagenomic screening on 885 ticks collected from 6 locations in Mongolia and divided the results into 68 samples: 23 individual samples and 45 pools of 2-12 tick samples each. We detected bacterial and parasitic pathogens Anaplasma ovis, Babesia microti, Coxiella burnetii, Borrelia miyamotoi, Francisella tularensis subsp. holarctica and novicida, Spiroplasma ixodetis, Theileria equi, and Rickettsia spp., including R. raoultii, R. slovaca, and R. canadensis. We identified the viral pathogens Crimean-Congo hemorrhagic fever virus (2.9%), recently described Alongshan virus (ALSV) (2.9%), and Beiji nairovirus (5.8%). We assembled ALSV genomes, and maximum-likelihood analyses revealed clustering with viruses reported in humans and ticks from China. For ALSV, we identified surface glycoprotein markers associated with isolates from Asia viruses hosted by Ixodes persulcatus ticks. We also detected 20 virus species of unknown public health impact, including a near-complete Yanggou tick virus genome. Our findings demonstrate that nanopore sequencing can aid in detecting endemic and emerging tickborne pathogens.

Silent Public Threat: Crimean-Congo Hemorrhagic Fever Outbreak Spikes During Eid-al-Adha in Afghanistan (Reported Cases to National Surveillance System, 2015-2024)

Silent Public Threat: Crimean-Congo Hemorrhagic Fever Outbreak Spikes During Eid-al-Adha in Afghanistan (Reported Cases to National Surveillance System, 2015-2024)

Combining Morphological and Molecular Tools Can Enhance Tick Species Identification for Improved Tick-Borne Disease Surveillance Among Pastoral Communities in Kenya.

Background: Ticks are ecto-parasites of domestic animals, rodents, and wildlife living for periods at a time on one or more vertebrate hosts. They are important vectors of viral, bacterial, or parasitic diseases in livestock and humans. Crimean-Congo haemorrhagic fever virus and the spotted fever rickettsiae are some of the tick-borne diseases of public health importance reported in Kenya. Their distribution and public health risks among communities, especially pastoralists, remain poorly characterized due to limited surveillance, affected partly by inadequate capacity for tick identification arising from a limited number of skilled taxonomists. Materials and Methods: The aim of this survey was to identify tick species currently circulating in different livestock hosts in northern Kenya. Ticks were sampled from cattle, sheep, goats, and camels in Turkana, Isiolo, Baringo, and West Pokot counties, and differential identification was carried out using morphological identification keys followed by molecular characterization based on the cytochrome c oxidase I gene (cox1). Haplotypes were determined using the DnaSP v6 software and phylogenetic relationships inferred using the maximum likelihood algorithm. Results: A total of 12,206 ticks were collected, from Turkana (45.4%), Isiolo (23.1%), Baringo (22.7%), and West Pokot (8.8%) counties in Kenya. Ten species were confirmed by molecular analysis; H. rufipes, H. impeltatum, H. dromedarii, R. pravus, R. camicasi, R. pulchellus, R. evertsi evertsi, A. variegatum, A. gemma, and A. lepidum. There was no disparity in the morphological and molecular identification of Amblyomma species. However, molecular analysis provided insight into the complexity of morphological identification especially among Hyalomma and Rhipicephalus species. High haplotype diversities (0.857-1.000) and low nucleotide diversities (0.00719-0.06319) were observed in all the tick samples tested. Conclusion: The findings highlight the diversity of tick species in dry pastoral ecologies in Kenya and the importance of confirming morphological identification by molecular analysis thus contributing to accurate mapping of tick-borne disease distribution and risk.

Seroprevalence of seven arboviruses of public health importance in sub-Saharan Africa: a systematic review and meta-analysis.

The arboviruses continue to be a threat to public health and socioeconomic development in sub-Saharan Africa (SSA). Seroprevalence surveys can be used as a population surveillance strategy for arboviruses in the absence of treatment and vaccines for most arboviruses, guiding the public health interventions. The objective of this study was to analyse the seroprevalence of arboviruses in SSA through a systematic review and meta-analysis. We searched PubMed/MEDLINE, Web of Science, Embase, Scopus and ScienceDirect databases for articles published between 2000 and 2022 reporting the seroprevalence of immunoglobulin G (IgG) antibodies to seven arboviruses in various human populations residing in SSA. The included studies were assessed using the checklist for assessing the risk of bias in prevalence studies, and the data were extracted using a standard form. A random effects model was used to estimate pooled seroprevalences. The potential sources of heterogeneity were explored through subgroup analyses and meta-regression. The protocol had been previously registered on International Prospective Register of Systematic Reviews with the identifier: CRD42022377946. A total of 165 studies from 27 countries, comprising 186 332 participants, were included. Of these, 141 were low-risk and 24 were moderate-risk. The pooled IgG seroprevalence was 23.7% (17.9-30.0%) for Chikungunya virus, 22.7% (17.5-28.4%) for dengue virus, 22.6% (14.1-32.5%) for West Nile virus, 16.4% (7.1-28.5%) for yellow fever virus, 13.1% (6.4-21.7%) for Zika virus, 9.2% (6.5-12.3%) for Rift Valley fever virus and 6.0% (3.1-9.7) for Crimean-Congo haemorrhagic fever virus. Subgroup and meta-regression analyses showed that seroprevalence differed considerably between countries, study populations, specific age categories, sample sizes and laboratory methods. This SRMA provides information on the significant circulation of various arboviruses in SSA, which is essential for the adoption and planning of vaccines. These findings suggest the need to invest in surveillance and research activities on arbovirus in SSA countries to increase our understanding of their epidemiology to prevent and respond to future epidemics.

The effect of VEGF and KDR gene variants on Crimean-Congo hemorrhagic fever

Background Crimean-Congo hemorrhagic fever (CCHF), an acute viral hemorrhagic fever disease, has a high mortality rate among humans. Hemorrhagic propensity is caused by coagulation malfunction and increased capillary permeability brought on by the resultant vascular injury. Vascular endothelial growth factor (VEGF) and VEGF receptor-2, or KDR (kinase insert domain containing receptor), are effective in vasculogenesis and angiogenesis. CCHF was stated to have endothelial dysfunction. This study aimed to evaluate whether the VEGF and KDR gene variants contribute to the development of CCHF in the Turkish population. Methods A total of 101 subjects, including 51 CCHF patients and 50 healthy controls, were included in the study. The polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) method was used to genotype VEGF 936 C > T (rs3025039) and KDR − 604 T > C (rs2071559) variants. The results were statistically analyzed. Results The VEGF 936 C > T genotype and allele distributions did differ significantly between the patients and the controls. The subjects carrying the C/C genotype and C allele had a higher risk of developing CCHF than the control group (p˂0.05). There was a statistically significant association between the controls and the patients in terms of VEGF 936 C > T C/C versus C/T + T/T (p˂0.05, OR:3.273, 95%Cl: 1.44–7.63). The KDR − 604 T > C variant’s allele and genotype distribution were not significantly different between the patients and controls. Conclusion This study suggests the VEGF 936 C > T variant is a genetic marker of sensitivity to CCHF among the Turkish population and may help protect against the disease.

Effect of dexamethasone therapy in Crimean-Congo hemorrhagic fever in Giresun during 2021-2023: an analytical study.

Crimean-Congo hemorrhagic fever (CCHF) is a zoonotic disease and significant health concern particularly in endemic regions. We aimed to evaluate the efficacy in dexamethasone treatment on clinical outcomes in CCHF patients. We included adult patients diagnosed with CCHF and those whose platelet count dropped to 70,000/mm3 or lower. The efficacy of dexamethasone on clinical outcomes was evaluated. It was a retrospective analytical study. The study included 55 patients. All patients received standard supportive treatment, and none of them received ribavirin therapy. It was observed that 23 (41.8%) of the patients were treated with dexamethasone. No significant differences were observed between patients treated with dexamethasone and those without dexamethasone treatment, regarding factors such as bleeding incidents during hospitalization, the need for blood product transfusions, thrombocyte recovery status, intensive care unit admission, and in-hospital mortality. In-hospital mortality was observed in two patients among all patients (3.6%). Our study found that dexamethasone treatment did not lead to a significant improvement in clinical outcomes for CCHF patients.

Determinants of crimean-congo hemorrhagic fever (cchf) outbreaks: a retrospective analysis

Abstract Introduction Crimean-Congo Hemorrhagic Fever (CCHF), a viral tick-borne zoonotic disease with high mortality rates, poses a particular threat in Pakistan during religious event of Eid-ul-Azha as increased livestock contact. This study aims to analyze CCHF cases from three outbreaks, to identify transmission and disease patterns. Understanding these patterns can inform targeted interventions for future outbreaks. Methods A retrospective cross-sectional study was conducted to examine three CCHF outbreak investigations between July 2nd and August 12th, 2023 in Khyber Pakhtunkhwa, Pakistan. Multisectoral teams, including human and animal health departments, investigated these outbreaks. Data was collected through semi-structured case investigation tools. The healthcare providers, patients and family were subjects. During active case surveillance, 41 probable contacts were traced. Results Among positive cases, male predominance (71.4%) was observed. The highest proportion of cases occurred in the 15-29 year age group (42.9%, n = 6). Individuals involved in animal handling professions had the highest prevalence (50%, n = 7), followed by students (21.4%, n = 3). Common clinical manifestations included high-grade fever (100%), muscle pain (92.9%), and bleeding symptoms (85.7%), with 64.3% of cases reporting vomiting blood. The average recovery time was 7.1 days, while fatal cases had an average of 6.8 days from symptom onset to death. Recovery was observed in 64.3% of cases, with a mortality rate of 35.7%. Chi-square analysis showed significant associations between gender, occupation, and disease outcome (p < 0.05). Conclusions This study identified a higher risk of CCHF in males, young adults, and individuals involved in animal handling during outbreaks. Public health interventions targeting occupations, demographics, particularly education and protective measures for animal handlers during Eid-ul-Azha days, are crucial to mitigate future outbreaks Key messages • Young male adults, and individuals involved in animal handling are on greater risk of higher risk of CCHF infections in Khyber Pakhtunkhwa, Pakistan. • One Health community can leverage these findings to develop better prevention and control strategies through collaboration between human and animal health sectors.

Preventive interventions on vector-borne diseases related to climate change: an Umbrella review

Abstract Background Vector-borne diseases (VBDs) are a global challenge to public health, being influenced by ecological factors and climate change. Despite the several preventive public health interventions that can be implemented, the evidence of their impact is still fragmented. An organic overview of the current evidence can provide relevant information on the effectiveness of these actions. Methods We conducted an umbrella review following the PRIOR checklist. Relevant reviews were searched using PubMed and Cochrane databases. We considered eligible all systematic reviews published in English between 2013 and 2023, containing meta-analysis on public health interventions aimed at reducing incidence, prevalence, or the burden of disease of VBDs, without demographic restrictions. Results We screened 1971 records. 51 reviews were included. 38 reported outcomes targeting Malaria, 9 Dengue, 2 Yellow Fever, 1 Leishmaniasis,1 Zika, 1 Chikungunya, 1 Crimean-Congo haemorrhagic fever, 1 Lyme disease and 1 Schistosomiasis. Several interventions were assessed worldwide. 18 reviews considered chemoprophylaxis, 9 net/curtains, 8 vaccines, 6 repellents, 3 housing interventions, 2 community participation, 2 MTaT and 2 oral supplementations. Authors stated conclusions are favourable to the interventions assessed for the 73%, but the certainty level is mostly considered low. Conclusions Public health preventive interventions are fundamental in responding to the threat of VBDs, but their impact may vary depending on several factors. Further research must provide more effective interventions and strategies, with a cohesive presentation of their evidence. Key messages • Effective reduction of VBDs burden requires a combination of interventions that must be tailored to local ecological, social, and epidemiological factors. • Evidence presented in this umbrella review can inform evidence-based policies and programs aimed at combating VBDs at local, national, and global levels.

Antibodies targeting the Crimean-Congo Hemorrhagic Fever Virus nucleoprotein protect via TRIM21

Crimean-Congo Hemorrhagic Fever Virus (CCHFV) is a negative-sense RNA virus spread by Hyalomma genus ticks across Europe, Asia, and Africa. CCHF disease begins as a non-specific febrile illness which may progress into a severe hemorrhagic disease with no widely approved or highly efficacious interventions currently available. Recently, we reported a self-replicating, alphavirus-based RNA vaccine that expresses the CCHFV nucleoprotein and is protective against lethal CCHFV disease in mice. This vaccine induces high titers of non-neutralizing anti-NP antibodies and we show here that protection does not require Fc-gamma receptors or complement. Instead, vaccinated mice deficient in the intracellular Fc-receptor TRIM21 were unable to control the infection despite mounting robust CCHFV-specific immunity. We also show that passive transfer of NP-immune sera confers significant TRIM21-dependent protection against lethal CCHFV challenge. Together our data identifies TRIM21-mediated mechanisms as the Fc effector function of protective antibodies against the CCHFV NP and provides mechanistic insight into how vaccines against the CCHFV NP confer protection.

Biological Characteristics of the Cytochrome P 450 Family and the Mechanism of Terpinolene Metabolism in Hyalomma asiaticum (Acari: Ixodidae).

The CYP450 enzyme is a superfamily enzyme ubiquitously found in nearly all organisms, playing a vital role in the metabolism of both endogenous and exogenous compounds, and in biosynthesis. Unfortunately, an understanding of its classification, functions, expression characteristics, and other biological traits in Hyalomma asiaticum, a vector for Crimean-Congo Hemorrhagic Fever, as well as of the genes implicated in its natural product metabolism, is lacking. Towards this end, this study has identified 120 H. asiaticum CYP450 genes via transcriptome data in the face of a joint genome threat from terpinolene. The proteins these genes encode are of higher molecular weight, devoid of a signal peptide, and composed of unstable hydrophobic proteins principally containing 1-3 variable transmembrane regions. Phylogenetic evolution classifies these H. asiaticum CYP450 genes into four subfamilies. These genes all encompass complete CYP450 conserved domains, and five specific conserved motifs, albeit with different expression levels. GO and KEGG annotation findings suggest a widespread distribution of these CYP450 genes in many physiological systems, predominantly facilitating lipid metabolism, terpenoid compound metabolism, and polyketone compound metabolism, as well as cofactor and vitamin metabolism at a cellular level. Molecular docking results reveal a hydrophobic interaction between the ARG-103, ARG-104, LEU-106, PHE-109, and ILE-119 amino acid residues in CYP3A8, which is primarily expressed in the fat body, and terpinolene, with a notably up-regulated expression, with affinity = -5.6 kcal/mol. The conservation of these five key amino acid residues varies across 12 tick species, implying differences in terpinolene metabolism efficacy among various tick species. This study thereby fills an existing knowledge gap regarding the biological characteristics of H. asiaticum CYP450 genes and paves the way for further research into the functions of these particular genes.

Crimean-Congo hemorrhagic fever in Herat province of Afghanistan, 2007-2021

Crimean-Congo hemorrhagic fever (CCHF) is a geographically widespread tick-borne hemorrhagic diseasecaused by the Crimean-Congo hemorrhagic fever virus (CCHFV). In Afghanistan, the first case of CCHF wasdetected in Takhar province in 1998, after which no additional cases were reported for ten years. The aim ofthis study is to report the analyses of the clinical and epidemiological features of confirmed CCHF cases thatwere recorded in Herat province between 2007 and 2021. This prospective case series study was conducted atHerat Regional Hospital between January 2007 and December 2021. Demographic and clinical data werecollected for each patient; all patients were hospitalized. Biochemical and hematological laboratoryexamination, and the detection of CCHV IgM and viral RNA was performed for all patients. Statistical analyseswere performed in IBM SPSS Statistics (version 26). A total of 252 confirmed CCHF cases including 160(63.5%) males and 91 (36.5%) females, with a mean age of 33.37±14.1 years were included in the study. Themajority of patients were in 11-50 age category, 32.9% were housewife, 38.4% were farmers, shephard, andbutchers. The most prevalent clinical presentations were fever (100%), headache (98.8%), body pain (96.4%),Ecchymosis (48.0%), epistaxis (44.8%) and gum bleeding (33.3%). The majority of cases occurred betweenApril and October. The case fatality rate of CCHF in this study was 2.8%. Considering the significant social,economic and health burden CCHF places on the community, enhanced public health measures are necessaryto control CCHF in Herat province and neighboring regions.

Serological evidence of tick-borne Crimean-Congo haemorrhagic fever and Dugbe orthonairovirus infections in cattle in Kwara State in northern Nigeria indicate independent endemics.

Crimean-Congo haemorrhagic fever orthonairovirus (CCHFV) and Dugbe orthonairovirus (DUGV) are zoonotic viruses transmitted by ticks. Whereas CCHFV has caused numerous human cases, DUGV, although less reported, shares ticks and ruminants as hosts. Since its first discovery in Nigeria in 1964, there has been no detailed sero-epidemiological investigation on DUGV in sub-Saharan Africa. This study is aimed at assessing the current seroprevalence and associated risk factors of CCHFV and DUGV infections in Nigerian cattle. Using a cross-sectional design with random sampling method, blood samples were collected from 877 cattle on pastoralist farms and at abattoirs in Kwara State, North-Central Nigeria. CCHFV IgG antibodies were detected in extracted sera using three panels of in-house indirect enzyme-linked immunosorbent assay (ELISA) based on bacteria-expressed recombinant nucleoprotein (rNP), the cattle-adapted VectoCrimean ELISA and the ID Screen CCHF double antigen multi-species ELISA, while DUGV IgG antibodies were detected using in-house indirect ELISA with bacteria-expressed rNP, indirect immunofluorescence assay and micro-Virus Neutralization test. Overall seroprevalence rates of 71.9% (631/877) and 52.8% (451/854) were obtained for CCHFV and DUGV, respectively. It was observed that 37.9% (314/829) of the cattle were co-exposed to both CCHFV and DUGV while 34.5% (286/829), 14.8% (123/829) and 12.8% (106/829) were exposed to single infections with CCHFV, DUGV or none of the two viruses, respectively. Multivariate analysis showed that only location, sex, age and tick infestation score were the risk factors that significantly affected CCHFV seroprevalence in cattle, while DUGV seroprevalence was significantly influenced by month of the year, location, cattle breed and sex (p<0.05). This is the first comprehensive sero-epidemiological surveillance for DUGV in sub-Saharan Africa. Our findings reveal widely distributed independent CCHFV and DUGV infections in cattle in Kwara State, Nigeria.

Knowledge, perception and attitude about Crimean-Congo Haemorrhagic Fever (CCHF) among veterinary students and professionals of Spain

The Crimean-Congo haemorrhagic fever (CCHF) is a tropical viral zoonosis first reported in Spain with 17 detected cases since 2010–2024. Health professionals, including veterinarians, play a crucial role in controlling and preventing this disease. This study aimed to analyse and compare the knowledge, perceptions, and attitudes of veterinary students and professionals in Spain regarding CCHF and zoonoses in general. Additionally, the study highlighted the value of epidemiological surveys as a tool for identifying knowledge gaps related to specific diseases. A cross-sectional survey was conducted from January to April 2024 among 4th and 5th-year veterinary students, Masters and Doctorate students, and veterinarians from the public and private sectors using a validated online questionnaire. A total of 135 individuals participated, 80.7 % professionals and 19.3 % students. The study found that 76.9 % of students and 64.2 % of veterinarians had good or very good knowledge of CCHF, yet significant gaps remained, particularly in epidemiology and diagnosis. Notably, only 34.8 % had good or very good knowledge of the disease’s situation in Spain, and many respondents felt their training and the information provided by official sources were inadequate. Additionally, the perception of infection risk from pets and attitudes towards preventing zoonoses through medication, vaccination, or regular analysis were concerning. Despite CCHF being an emerging disease in Spain, this survey—the first in Spain and Europe—reveals that veterinarians’ knowledge and attitudes in affected regions are not as advanced as needed, underscoring the importance of targeted epidemiological surveys on the knowledge of the disease.

Crimean Congo hemorrhagic fever virus exposure among febrile patients, cattle herders, and cattle herds in Cameroon

Problem addressedCrimean Congo hemorrhagic fever (CCHF) is a tick-borne disease with high fatality rates and an expansive geographic distribution, yet disease prevalence data in Cameroon is lacking. ObjectiveThis study aimed to determine CCHF virus (CCHFV) seroprevalence and tick distribution among cattle herders and febrile patients in West and Centre Cameroon. Methods and approachTwo cross-sectional serological studies of human and cattle were conducted from October to December 2021 and from June to July 2022, which included the collection of ticks. Enzyme-linked immunosorbent assay (ELISA) were used to detect anti-CCHFV antibodies, while a knowledge, attitudes, and practice (KAP) survey assessed tick and tickborne disease related knowledge and behaviors among herders. Tick identification used morphological keys. ResultsThe KAP survey showed adequate tick knowledge (94.5 %) among herders but poor understanding of disease transmission, with favorable attitudes towards tick control (24.7 %) but inadequate implementation. Rhipicephalus annulatus (64.1 %) predominated among the 1,296 ticks collected during each rainy season. Among cattle, 27.4 % were seropositive, and seropositivity was associated with specific villages, cattle age (>4 years), and female sex. Herders had a 17.8 % seroprevalence, while febrile patients had 8.3 %, with higher rates in those >20 years old for both groups. Self-reported tick removal by herders after contact and grazing may increase CCHFV exposure. ConclusionsThis study confirms CCHFV circulation in rural West Cameroon and unexpected exposure risk in Yaounde, highlighting the need for active entomological surveillance and preventive measures in transhumance and cattle market activities. Establishing an occupation-based surveillance system can help identify CCHFV hotspots to prevent outbreaks.

Crimean-Congo hemorrhagic fever cases diagnosed during an outbreak of Sudan virus disease in Uganda, 2022-23.

In September 2022, Uganda experienced an outbreak of Sudan virus disease (SVD), mainly in central Uganda. As a result of enhanced surveillance activities for Ebola disease, samples from several patients with suspected viral hemorrhagic fever (VHF) were sent to the VHF Program at Uganda Virus Research Institute (UVRI), Entebbe, Uganda, and identified with infections caused by other viral etiologies. Herein, we report the epidemiologic and laboratory findings of Crimean-Congo hemorrhagic fever (CCHF) cases that were detected during the SVD outbreak response. Whole blood samples from VHF suspected cases were tested for Sudan virus (SUDV) by real-time reverse transcription-polymerase chain reaction (RT-PCR); and if negative, were tested for CCHF virus (CCHFV) by RT-PCR. CCHFV genomic sequences generated by metagenomic next generation sequencing were analyzed to ascertain strain relationships. Between September 2022 and January 2023, a total of 2,626 samples were submitted for VHF testing at UVRI. Overall, 13 CCHF cases (including 7 deaths; case fatality rate of 53.8%), aged 4 to 60 years, were identified from 10 districts, including several districts affected by the SVD outbreak. Four cases were identified within the Ebola Treatment Unit (ETU) at Mubende Hospital. Most CCHF cases were males engaged in livestock farming or had exposure to wildlife (n = 8; 61.5%). Among confirmed cases, the most common clinical symptoms were hemorrhage (n = 12; 92.3%), fever (n = 11; 84.6%), anorexia (n = 10; 76.9%), fatigue (n = 9; 69.2%), abdominal pain (n = 9; 69.2%) and vomiting (n = 9; 69.2%). Sequencing analysis showed that the majority of identified CCHFV strains belonged to the Africa II clade previously identified in Uganda. Two samples, however, were identified with greater similarity to a CCHFV strain that was last reported in Uganda in 1958, suggesting possible reemergence. Identifying CCHFV from individuals initially suspected to be infected with SUDV emphasizes the need for comprehensive VHF testing during filovirus outbreak responses in VHF endemic countries. Without expanded testing, CCHFV-infected patients would have posed a risk to health care workers and others while receiving treatment after a negative filovirus diagnosis, thereby complicating response dynamics. Additionally, CCHFV-infected cases could acquire an Ebola infection while in the ETU, and upon release because of a negative Ebola virus result, have the potential to spread these infections in the community.