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Crimean-Congo hemorrhagic fever (CCHF) - Molecular diagnosis (RT-PCR).

Information 06/09/16.

The Crimean-Congo hemorrhagic fever (CCHF: Crimean-Congo Hemorrhagic Fever) is caused by a virus with the same name (CCHFV). This virus is included in the Bunyaviridae, genus Nairovirus family, and is characterized by having a genome of single stranded RNA (ss RNA) of negative sign, divided into three segments: L, M and S. The (large, Large) L segment encodes RNA viral polymerase the; M (medium) segment encodes the surface glycoproteins G1 and G2; and segment S (small, Small) encodes the nucleocapsid protein (N). This virus has a genetic variability which has made consider the existence of six phylogenetic branches: I, including strains of West Africa (Senegal); II, with the strains of Democratic Republic of Congo (and Uganda); III, with strains of Southern Africa, West and East (South Africa, Nigeria, Sudan); IV, with Asian and Middle Eastern strains (China, Pakistan, Iran, Iraq, Oman, Uzbekistan and Tajikistan); V, with European strains (Russia, Turkey, Kosovo); and VI, with the Greek AP92 strain isolated from the tick Ripicephalus bursa.

The first clinical descriptions of this disease occurred in Crimea (1944) when 200 Soviet soldiers in this region were affected during World War II. The virus was identified in 1967, and was found to be similar to a virus previously described in Congo (1956), so virus Crimean-Congo hemorrhagic fever was called. The virus has a wide geographical distribution: Africa, Asia, Middle East, Eastern Europe and Southern Europe. Southern Europe, the Balkan region is considered an endemic region with the appearance of sporadic cases and outbreaks annually. In Spain we had a first case recently with a secondary case in a toilet.

Clinical manifestations: have differentiated four distinct phases in the course of the disease: incubation period (3 to 7 days); prehemorrágica phase (4-5 days); hemorrhagic phase (2 to 3 days); and convalescent (10 to 20 days). Prehemorrágica in the initial phase, patients develop a fever of sudden onset, high fever of 39 to 41 ° C, chills, severe headache, malaise, facial flushing, myalgia, arthralgia, dizziness, nausea, ..., and the the most striking of hemorrhagic disease stage, and what is called "hemorrhagic fever" are the cutaneous and mucosal bleeding manifestations (cutaneous petechiae, epistaxis, bruising, hematemesis, bloody diarrhea, ...). The presence of visceral hemorrhage is considered a sign of poor prognosis. They have also been reported mild cases in which there has been no type of hemorrhagic phenomenon. Mortality has indicated that it can reach 30% with wide margins (5 to 60%).

Transmission mechanisms: the virus has as a reservoir for various types of animals (sheep, goats, cattle, ...) and infected ticks. Ticks are the main transmission mechanism. It noted the tick Hyalomma spp, the main vector, but the virus has been found in up to 31 different species of ticks five different genres both group hard ticks (Ixodidae:.. Hyalomma spp, Rhipicephalus spp. , Dermacentor spp, Haemaphysalis spp), as the soft ticks (Argasididae:... Ornithodorus spp), with prevalence of infections in different studies between 0.2 and 33%.

During disease virus found in biological fluids of the patient (blood, saliva, respiratory secretions, urine, ...), so it is common human transmission. This form of inter - human transmission has been found frequently in health workers who treat patients but also family members who have been in contact with the patient at home.

Another method of transmission is through contact with infected animals or their tissues, so that contact with blood or tissues of viremic cattle should be avoided. In addition, there are occasional infections such as those due to the ingestion of raw meat products from infected animals (eg., Ingestion of raw liver in Sudan).

For the foregoing reasons, they are considered preferential risk groups pastoralists, farmers, veterinarians, health workers and soldiers.

Antiviral treatment: Ribavirin has been used, although the mechanism of action against the virus is unknown and there are no randomized clinical trials supporting its usefulness, but effects have been observed in observational studies. When used it should be given at the beginning of the disease.

Protective measures: to prevent inter - human transmission is recommended mask, goggles, double pair of gloves and waterproof coat.

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