The clinical illness associated with CCHFV is a severe form of hemorrhagic fever. Following infection by a tick bite, the incubation period is typically two to three days but can last as long as nine days, while the incubation period following contact with infected blood or tissues is usually five to six days with a documented maximum of 13 days. The onset of symptoms ushering in the prehemmorhagic phase is sudden, with fever, myalgia, (muscle ache), dizziness, neck pain and stiffness, backache, headache, sore eyes and photophobia (sensitivity to light). Typical symptoms include nausea, vomiting (which may progress to severe bleeding and can be fatal if not treated), diarrhea, abdominal pain and sore throat early in the acute infection phase, followed by sharp mood swings, agitations and confusion. After several days, agitation may be replaced by sleepiness, depression and lassitude, and the abdominal pain may localize to the upper right quadrant, with detectable liver enlargement. As the illness progresses into the hemorrhagic phase, large areas of severe bruising, severe nosebleeds, and uncontrolled bleeding at injection sites can be seen, beginning on about the fourth day of illness and lasting for about two weeks. Other clinical signs include tachycardia (fast heart rate), lymphadenopathy (enlarged lymph nodes), and a petechiae (a rash caused by bleeding into the skin) on internal mucosal surfaces, such as in the mouth and throat, and on the skin. The petechiae may give way to larger rashes called ecchymoses, and other haemorrhagic phenomena. There is usually evidence of hepatitis, and severely ill patients may experience rapid kidney deterioration, liver failure or pulmonary failure after the fifth day of illness. In documented outbreaks of CCHF, fatality rates in hospitalized patients have ranged from 9% to as high as 70%, though the WHO notes a typical range of 10-40%, with death often occurring in the second week of illness. In patients who recover, improvement generally begins on the ninth or tenth day after the onset of illness. The long-term effects of CCHF infection have not been studied well enough in survivors to determine whether or not specific complications exist. However, recovery is slow.
Crimean–Congo hemorrhagic fever
Ebola
Omsk hemorrhagic fever
Dengue fever
Bolivian hemorrhagic fever
Q fever
Blackwater fever
Argentine hemorrhagic fever