A Review on the Reappearance of Crimean-Congo Hemorrhagic Fever, a Tick-Borne Nairovirus

Introduction and Objectives: Crimean-Congo Hemorrhagic Fever (CCHF) is the second most widely distributed arboviral disease worldwide. CCHF is transmitted to humans mainly by bites of infected ticks in the Ixodidae family, mainly those of the Hyalomma genus or via human contact with the blood and tissues of infected livestock. It can also be transmitted to a healthy individual through close contact with an infected person (like a nosocomial infection). Given the importance of CCHF, this review study was carried out in Iran with an emphasis on the importance of the vectors. Materials and Methods: In this review study, using keywords such as epidemiology, Crimean-Congo hemorrhagic fever, arbovirus, vectors, reservoirs, distribution, and control, by searching relevant websites and accredited medical journals and considering the purpose of the study, the appropriate articles were selected and the disease status in Iran from 1965 to 2019 was analyzed. Results: CCHF has been reported from 26 provinces of Iran. Sistan-Baluchestan province has always been among the most infected areas due to livestock smuggling from neighboring countries. The tick vectors are widespread and abundant in Iran. The main ones are the Hyalomma marginatum and Hyalomma anatolicum species. The prevalence of the disease is higher in warm seasons of the year when vectors are more active. In Iran, most cases are caused by contact with infected livestock. Direct infection through tick bites is rare and only a few such cases have been reported. Middle Eastern countries are divided into 6 groups based on the levels of healthcare systems and the numbers of CCHF cases reported annually. Iran is allocated into group one due to annual reports of the disease and has designed a healthcare system for this disease. Conclusions: To control CCHF, people, especially high-risk groups, must be educated about routes of transmission and prevention of CCHF. In addition, given that viremic livestock is the major source of CCHF outbreaks in Iran, livestock smuggling and non-hygienic and traditional livestock slaughter procedures must be prevented and infected livestock must be treated.