Crimean Congo Hemorrhagic fever (CCHF)

Describing the disease situation

A picture of Hyalomma ticks ©NCID/Bob Swanepoel

Crimean-Congo Hemorrhagic Fever (CCHF) is a zoonosis that can be transmitted through tick bites, through contact with crushed infected ticks, through contact with viraemic tissues of infected wild or domestic animals during and immediately post-slaughter or through person to person transmission by contact with infectious blood or body fluids. Documented spread of CCHF has also occurred in hospitals due to improper sterilization of medical equipment, reuse of injection needles, and contamination of medical supplies. Even though animals transiently infected with CCHF do not develop disease signs, CCHF is a notifiable disease to the World Organisation for Animal Health (OIE) according to the requirements on notification of diseases set out in Chapter 1.1.2. of the OIE Terrestrial Animal Health Code. The relevance of this disease for OIE notification is not related to the consequences of its spread within the animal population, but rather to the risk posed by its zoonotic potential. Better monitoring of CCHF in animals by Veterinary Services is an important step to avoid human fatalities.

The disease is known as one of the most important viral haemorrhagic fevers (VHF) in people because of its high case fatality ratio (10-40%) and its potential for nosocomial transmission.

CCHF is endemic in Africa, the Balkans, the Middle East and Asia south of the 50° parallel north which corresponds with the limit of distribution of the Hyalomma tick. Over the last several years sporadic human cases and limited outbreaks have been increasingly reported every year. Outbreaks of CCHF have been recorded in Afghanistan (2001 to 2008), Armenia (2006), Iran (2001-2009), Kazakhstan (2005, 2009), Kosovo (2001 to 2008), Bulgaria (1955 to 2008), Mauritania (2002 to 2003), Pakistan (2001 to 2009), Russia (1999 to 2009) Senegal (2004 with a human imported case in France) South Africa (1989 to 2009), Sudan (2004, 2008), Tajikistan (2002, 2004, 2009), Georgia (2009), Serbia (2001, 2004, 2009), Greece (2008),and Turkey (2003 to 2009) have drawn the international community attention to this emerging problem. The trend seems to suggest increased human disease incidence with higher case fatality rates

National surveillance systems in animals have demonstrated the presence of CCHF in animals in Iran and in certain regions of Pakistan. The presence of the disease in animals is also suspected to be present in Russia.

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Trends in disease occurrence

Human CCHF case in South Africa with petechiae and ecchymoses ©NCID/Bob Swanepoel

In endemic areas, poverty and social instability, lack of vector control, insufficient medical equipment, and absence of infection control standards precautions all contribute to increase the transmission of the CCHF virus in the community or in hospital settings. Environmental changes like neglect of agricultural lands and subsequent agricultural and farming activity, and increase in wildlife populations are also known to increase the Hyalomma spp. tick population and therefore elevate the risk of exposure to tick-borne diseases.

CCHF outbreaks constitute a strain to public health services because of their high case fatality ratio and difficulties in their prevention and treatment. CCHF outbreaks can cause public health emergencies of national, regional and sometimes international importance.

Identifying gaps and proposing solutions

More effective measures to reduce viral transmission of CCHF are needed to curtail the growing magnitude of public health impact of this disease. Given the perceived increase in human CCHF cases, there is need to renew or intensify efforts for the prevention and control of the disease.

Priority areas for CCHF prevention and control:

Readiness and preparedness - Develop further forecasting models using remote sensing data for CCHF and link them with surveillance activities in order to help with CCHF outbreak readiness and preparedness:
- Coordinate the development of a common and comprehensive database of geo-locations of CCHF animal and human cases (this database will be checked for accuracy by field investigators);
- Use the CCHF database to produce accurate risk maps for CCHF;
- Evaluate the value of different forecasting models vis-à-vis the CCHF database and try to ameliorate specificity and sensitivity of theses.
Alert - Strengthen epidemiological surveillance in humans and animals, including laboratory diagnosis
- Support the continued CCHF surveillance (case definition, SOPs for surveillance etc);
- Support access to laboratory diagnosis in reference laboratories.
Outbreak response - Reduce the disease burden through
- Integrate standard operating procedures for outbreak response that include vector (ticks), animal and human health components;
- Design and perform "Train-the-Trainer" courses for CCHF outbreak response with EURO and EMRO regional teams;
- Develop standard case management training for CCHF;
- Develop a manual for healthcare providers that would include clinical descriptions, treatment options and recommended laboratory tests;
- Improve emergency preparedness and response;
- Strengthen national tick-control programmes.
Health Education - Develop a social mobilization standardized approach for CCHF disease based on Communication-for-Behavioural-Impact (COMBI) strategy and Medical anthropology network
- Develop, in key countries, a CCHF risk factor analysis during farm activities, tick bites, slaughtering activities, hospital functions and funeral rites for contracting CCHF;
- Identify key behavioural interventions for farms, home and health care settings.
Treatment of patients
- Organize consultations with partners and experts to review current strategy for CCHF treatment;
- Promote the development of multi-country randomized clinical trials for ribavirin that would be coordinated by WHO. This would involve a multi-center study to assess the efficacy of the drug and an international working group.
Ticks and vector control
- Promote / organize tick surveys that would be conducted in countries where outbreaks occur using standard protocols for tick collection and for ecological research;
- Standardize protocols for tick collection from humans: ticks should be identified and then screened for a broad range of pathogens in addition to CCHF virus;
- Develop further studies about the role of domestic livestock and wild animal populations in the epidemiology of CCHF (ecological studies);
- Develop further studies with integrated tick control strategies for livestock using anti-tick vaccines (in development), acaricides, and an anti-CCHF animal vaccine to decrease animal viraemia;
- To develop further studies into the use of tick repellents for both human and animals.
Prevent underreporting of CCHF
- Raise awareness about the public health risk of under-reporting of CCHF and implications of untreated CCHF;
- Revise international animal health policies to disperse fear of potential livestock trade bans.

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Prevention of transmission

Reducing the risk of infection in people

In the absence of a vaccine, the only way to reduce infection in people is by raising awareness of the risk factors and educating people about the measures they can take to reduce their exposure to the virus.

Public health educational messages should focus on the following:

Reduce the risk of animal-to-human transmission
- eliminating or at least controlling tick infestations on animals or in stables/barns;
- quarantine for animals before they enter slaughterhouses or routine treatment of ruminants with pesticides 2 weeks prior to slaughter;
- using masks, gloves and gowns when slaughtering and butchering animals.
Reduce the risk of tick-to-human transmission
- avoid tick bites (use of approved acaricide and repellent, appropriate clothing, frequent body inspection searching for ticks);
- remove ticks safely from the skin.
Reduce the risk of tick-to-human transmission in the community arising from direct or close contact with infected patients, particularly with their body fluid. Close physical contact with CCHF patients should be avoided. Gloves and appropriate personal protective equipment should be worn when taking care of ill patients at home. Regular hand-washing after visiting sick relatives in hospital, as well as while taking care of ill patients at home should be carried out.

Controlling infection in health-care settings

Human-to-human transmission of CCHF virus is primarily associated with direct contact with blood and body fluids, and CCHF virus transmission to healthcare workers has been reported when appropriate infection control measures have not been observed.

In the CCHF outbreak foci area, healthcare workers caring for patients with suspected or confirmed CCHF should apply infection control precautions to avoid any exposure to the patient’s blood and body fluids and/or direct unprotected contact with possibly contaminated environment. Provision of health care for suspected or confirmed CCHF patients require specific control measures and reinforcement of Standard Precautions, particularly basic hand hygiene, use of personal protective equipment, safe injections practices and safe burial practices. Current infection control recommendations for provision of direct and non-direct care to patients with suspected or confirmed CCHF should follow the ones described in the document: “Interim Infection Control Recommendations for Care of Patients with Suspected or Confirmed Filovirus (Ebola, Marburg) Haemorrhagic Fever, March 2008”. The document is available at the following link (PDF, 7pp).
Laboratory workers are also at risk. Samples taken from humans and animals with suspected CCHF infection should be handled by trained staff and processed in suitably equipped laboratories.

GLEWS