History and exam
Key diagnostic factors
common
presence of risk factors
Key risk factors include history of tick exposure; contact with a human or an animal with CCHF infection; and residency in or travel to a CCHF-endemic region.
fever
The majority of patients have a recorded fever or history of fever at presentation, but the absence of these does not exclude early/mild CCHF. The fever does not follow a pattern of regular intervals as in malaria.
myalgia
Can be intense, similar to severe influenza.
malaise
More severe than in common diseases such as influenza.
bleeding
Most commonly nasal or gingival bleeding, although it can be from anywhere. Vaginal bleeding has been reported.[74] Prolonged menstruation may be the only symptom.
macular or petechial rash
Initially a macular rash, which then progresses to a petechial rash.
Other diagnostic factors
common
headache
A non-specific sign of the early influenza-like phase.
nausea
Can be seen together with other influenza-like symptoms.
abdominal pain
May occur early on and then localise to the right upper quadrant (associated with hepatomegaly).[51] May be more common in children.
hepatomegaly
Can be detected in moderately to severely ill patients.
splenomegaly
Can be detected in severely ill patients.
somnolence
Occurs after 2 to 4 days; may be a sign of severity.[51]
uncommon
diarrhoea
Does not often occur in adults, but may be a more common symptom in children.
hypotension
May be seen as the disease progresses.
conjunctivitis
Acute haemorrhagic conjunctivitis. Other signs of bleeding should also be explored.
arthralgia
There is no specific pattern in involvement of the joints.
Risk factors
strong
residency in or recent travel to CCHF-endemic region
A recent history of travel to a CCHF virus-affected country should prompt consideration of CCHF virus infection in a patient presenting with high fever and influenza-like symptoms, especially if any other risk factors are present.
Up-to-date knowledge of the geographical locations of active epidemics helps to clarify the patient’s epidemiological risk.
WHO: geographic distribution of Crimean-Congo haemorrhagic fever Opens in new window
history of tick exposure
Transmission to humans is primarily through the bite of an infected tick.
Ticks of the family Ixodidae (genus Hyalomma) are considered to be the main vectors that spread the virus to humans. The occurrence of CCHF closely approximates the known world distribution of Hyalomma ticks, with phylogenetic analyses revealing relations between strains from distant outbreaks. Although ticks of the genus Hyalomma are recognised as the main vector/reservoir of the virus, it has also been detected in ticks of the genuses Ornithodoros and Amblyomma. The role of tick species other than Hyalomma is not fully understood and requires further investigation.[33]
contact with infected body fluids
Contacts of infected patients (including healthcare workers and household contacts) are at risk of infection if the person was exposed to body fluids of the infected patient without appropriate protective equipment. Household contacts of infected patients are at a higher risk of infection if there is active diarrhoea, vomiting, or bleeding.
occupational exposure
Most cases occur in adults exposed to ticks during the course of their work (agriculture and/or husbandry).[30][31]
Healthcare workers are the second-most affected group.[31] Healthcare workers in contact with infected patients are at high risk.Healthcare workers in, and immediately outside, outbreak areas should implement standard infection-control precautions.[51]
contact with infected animals
This route of transmission is likely to be a cause of animal-to-human transmission in sporadic epidemics.
Transmission may occur due to contact with the animal's blood or during skinning of the animal; therefore, preventative measures should be followed by people handling animals in endemic areas. High-risk animals include: hares, cattle, sheep, goats, other wild and domestic ruminants, and ostriches. Other birds are considered to be low risk.[51][52]
A consensus report of preventative measures has been published to prevent transmission associated with animal sacrifice during Eid al-Adha.[53]
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