Epidemiological situation of Crimean-Congo hemorrhagic fever

Introduction

Crimean-Congo hemorrhagic fever (CCHF) is a viral zoonotic disease with up to 50% mortality rate in humans and belongs to the Nairovirus genus and Bunyaviridae family. CCHF manifests with four distinct phases including incubation, prehemorrhagic, hemorrhagic, and convalescence. The virus is transmitted to humans by infected tick bite, handling of infected blood or tissues, or nosocomially. In the present study, serological and molecular epidemiology of CCHF infection was surveyed among the Iranian population during the past decade.

Methods

From 2000 to 2010 (30 May), probable sera of the human population throughout the country were collected. Then, the sera were analyzed through serological (IgM and IgG specific ELISA) and molecular (gel-based and real-time RT-PCR) testing.

Results

As the results show, among 1,377 human probable sera collected from different parts of the country, 544 human cases were confirmed for CCHF and 79 CCHF death cases were reported to date. Sistan and Baluchistan (383 confirmed cases), Isfahan (44), Fars (26), Tehran (17), and Khorasan (12) were the most infected provinces, respectively. Slaughterers, butchers, and farmers, with 21.6%, 17.64%, and 17.46%, ranked the highest among professions, respectively. Also, 52.2% of confirmed cases were in an age range of 21 to 40 years and, interestingly, CCHF infection was shown in males (77.5%) more than females (22.5%).

Conclusions

Although CCHF has been confirmed in 23 out of 30 provinces of Iran, the disease has occurred with the highest grade in Sistan and Baluchistan during the past decade, certainly because of its proximity to Pakistan and Afghanistan, two countries with endemic CCHF. In the present study, it was demonstrated that CCHF was seen much more in the active age range and is more common in high-risk professions related to livestock such as butchers, slaughterers, and farmers. Therefore, it seems, informing the groups of high-risk professions has been efficient. Fortunately, with precise surveillance and laboratory detection, the mortality rate has been remarkably decreased recently.