Investigation of Crimean-Congo Hemorrhagic Fever Virus Transmission from Patients to Relatives: A Prospective Contact Tracing Study

Abstract

Abstract. We investigated the possibility of transmission of Crimean-Congo hemorrhagic fever (CCHF) virus through respiratory and physical contact. In this prospective study, we traced 116 close relatives of confirmed CCHF cases who were in close contact with the patients during the acute phase of the infection and evaluated the type of contact between patients and their relatives. These relatives were followed for clinical signs or symptoms indicative of CCHF disease, blood samples of those with and without clinical signs were analyzed for CCHF virus immunoglobulin M and G (IgM and IgG, respectively) by enzyme-linked immunosorbent assay. No close relatives developed any signs or symptoms of CCHF and were negative for CCHF virus IgM and IgG. The results suggest that CCHF virus is not easily transmitted from person to person through respiratory or physical contact.Crimean-Congo hemorrhagic fever (CCHF) is a tick-borne disease caused by CCHF virus (CCHFV), which belongs to the Bunyaviridae family, and Nairovirus genus.1,2 Human infections begin with nonspecific febrile symptoms but progress to a serious hemorrhagic disease. In severe cases, circulatory shock and disseminated intravascular coagulation may occur and result in death. [3][4][5][6] The fatality rate attributed to this infection is between 3% and 30%. 4,5,7,8 The CCHFV is generally transmitted to humans through the bite of Ixodid ticks or by contact with blood or tissue of infected livestock.3,5 Human-to-human transmission has been reported only by direct contact with viremic patients during the acute phase of infection. Needle stick injuries, gastrointestinal hemorrhage interventions, emergency surgical procedures, and unsafe handling of patients or their infected materials have been reported to be high-risk activities for CCHFV transmission; however, transmission through droplet, viral droplet, or physical contact has not been definitely tested.9-14 Moreover, transmission may occur by respiratory contact. 1 We conducted a prospective contact tracing study to investigate the possibility of CCHFV transmission through respiratory contact, including droplet and airborne, and ungloved physical contact with the patient or objects around the patient.This study was conducted at the Cumhuriyet University Hospital in Turkey, between June and September 2011. The CCHF patients were generally referred to our hospital 2-5 days after the initial onset of disease symptoms. This delay was primarily because of non-specific symptoms on the first several days of the infection. After confirmation of CCHF infection, the first degree relatives from the same household were identified and types of repeated contact between patients and their relatives were recorded. Some of these relatives were allowed to remain in the same hospital room as caregivers, because many patients and their relatives came from outside the city, had strong emotional ties and fear of death, and the relatives desired to be near the patients during what might be their last days; however, the use of prote...

Crimean-Congo hemorrhagic fever: Risk factors and control measures for the infection abatement

“…The virus can be transmitted from person to person through contact with animal blood or products, contact with infectious body fluids of an infected person and by handling the infected ticks (47). The areas outside the range of tick distribution are at little or no risk of exposure to ticks.…”

Unexpected Risks for Campers and Hikers: Tick-Borne Infections

“…Cases generally come from rural and farming areas. [46][47][48]52,58 Although CCHF and Tularemia are notifiable diseases in Turkey, there are not any case records for campers or hikers. For future studies, prospective or retrospective studies for tick-borne infections that focus on campers, hikers, climbers, and others should be conducted.…”

“…46,47 Person-to-person transmission is not an easy route for CCHF. 48 CCHF is transmitted by Hyalomma ticks which belong to the hard-bodied Ixodes family. 42 The geographic distribution of Hyalomma ticks is limited to a latitude of 48° north, which is the northern border of the world.…”

Biosafety standards for working with Crimean-Congo hemorrhagic fever virus

“…There are only a few reports describing the infection of close relatives of CCHFV patients, and these lack conclusive evidence of aerosol transmission (Saijo et al, 2004;Tezer et al, 2011). On the contrary, none of a cohort of 132 relatives staying with or visiting 88 CCHF patients of whom two patients died at the Cumhuriyet University Hospital in Turkey developed any symptoms nor seroconverted despite the fact that many did not comply with protective measures (Gozel et al, 2014). The study indicates that CCHF is not easily spread between humans and into the community.…”