Medicine chapters
Crimean-Congo haemorrhagic fever
Crimean-Congo haemorrhagic fever (CCHF) is a tick-borne viral haemorrhagic fever seen in Pakistan, especially around Eid ul-Adha. Learn its cause, spread, phases, tests, isolation and treatment.
- CCHF is caused by a Nairovirus (Bunyavirus order) carried by Hyalomma ticks; humans catch it from tick bites or blood of infected livestock, so cases rise around Eid ul-Adha in Pakistan.
- After a short incubation it causes sudden fever, myalgia and headache, then a haemorrhagic phase with large bruises, bleeding, very low platelets and raised liver enzymes.
- Confirm with RT-PCR; manage in isolation with strict barrier precautions, give supportive care and blood products, and consider ribavirin early; health workers are at real risk.
On this page
Overview
Crimean-Congo haemorrhagic fever (CCHF), often called "Congo fever" in Pakistan, is a severe tick-borne viral haemorrhagic fever. It is found across Africa, the Middle East, Central and South Asia and south-east Europe.
In Pakistan it is endemic, especially in Balochistan and Khyber Pakhtunkhwa, with cases reported from all provinces. Cases rise around Eid ul-Adha, when large numbers of animals are moved, kept in homes and slaughtered. The case fatality is high (often quoted as 10–40%), and hospital spread to health workers is well documented.
Aetiology
- Agent: CCHF virus, a Nairovirus in the Bunyavirales order (older books say family Bunyaviridae). It is an enveloped, negative-sense, segmented RNA virus.
- Vector and reservoir: ticks of the genus Hyalomma. Infected ticks stay infected for life and pass the virus to their eggs.
- Amplifying hosts: cattle, sheep, goats, hares and other animals. Animals become viraemic but usually show no illness.
Transmission to humans
- Tick bite or crushing an infected tick with bare hands.
- Contact with blood or tissues of viraemic animals, especially during or just after slaughter.
- Person-to-person: contact with blood, secretions or body fluids of a patient (nosocomial infection via needle-stick, splashes, unprotected care).
High-risk groups
- Herders, farmers, livestock traders, butchers and abattoir workers
- People handling animals around Eid ul-Adha
- Health workers (doctors, nurses, lab staff) and family carers
- Veterinarians
CCHF is one of the few viral haemorrhagic fevers that spreads readily from patient to health worker. Suspect it early and protect staff.
Pathophysiology
- The virus infects endothelial cells, macrophages and hepatocytes.
- Endothelial damage and cytokine release cause vascular leak, hypotension and shock.
- Platelet consumption, liver damage and DIC produce bleeding.
- High viral load and severe liver and clotting abnormalities predict death.
In CCHF, bleeding is often early and dramatic (large bruises, GI bleeding) with very high AST/ALT, whereas in dengue bleeding usually follows plasma leakage around defervescence.
Clinical features
Incubation
- After a tick bite: short, usually 1–3 days (up to about 9 days).
- After blood or tissue contact: usually 5–6 days (up to about 13 days).
Phases
| Phase | Duration | Features |
|---|---|---|
| Pre-haemorrhagic | About 3 days (1–7) | Sudden high fever, chills, severe headache, dizziness, neck and back pain, myalgia, photophobia, vomiting, diarrhoea, abdominal pain; flushed face, conjunctival injection; relative bradycardia may occur |
| Haemorrhagic | Short, usually 2–3 days | Petechiae then large bruises (ecchymoses), bleeding from gums, nose, injection sites, GI tract (haematemesis, melaena), haematuria, vaginal bleeding; hepatomegaly; drowsiness, confusion |
| Convalescence | From about day 10–20 | Weakness, fast pulse, hair loss, poor memory, neuritis; recovery is slow but usually complete |
- Severe cases develop shock, liver failure, kidney failure, ARDS and coma. Death usually occurs in the second week.
- Poor prognostic signs: very low platelets, very high AST/ALT, prolonged APTT and PT, low fibrinogen, raised D-dimer, high viral load, melaena, drowsiness.
Investigations
Routine tests (strong clues)
- Thrombocytopenia (often severe) and leucopenia early; leucocytosis may appear later.
- Raised AST and ALT (AST typically higher), raised LDH and CK.
- Prolonged PT and APTT, low fibrinogen, raised D-dimer (DIC).
- Haemoglobin falls with bleeding; creatinine rises with kidney injury.
Confirmation
| Test | When |
|---|---|
| RT-PCR on blood | First few days; test of choice for early diagnosis |
| IgM ELISA | From about day 5–7 onwards |
| IgG ELISA | Later, rising titres; shows past infection |
| Virus culture | Only in high-containment (biosafety level 4) laboratories |
- Label and transport samples as high-risk; inform the laboratory beforehand.
Differential diagnosis
| Condition | Features that help |
|---|---|
| Dengue | Aedes exposure, retro-orbital pain, bleeding usually after day 3 with rising haematocrit; liver enzymes less extreme |
| Malaria | Rigors, splenomegaly, positive film or RDT |
| Leptospirosis | Water or rodent exposure, calf pain, conjunctival suffusion, jaundice with kidney injury |
| Rickettsial infection (typhus) | Eschar, rash; responds to doxycycline |
| Meningococcal sepsis | Purpuric rash, meningism, rapid shock |
| Severe sepsis with DIC, viral hepatitis, acute leukaemia, ITP, TTP | History and blood film |
A patient with fever and bleeding after slaughtering or handling animals, or after a tick bite, must be treated as CCHF until proved otherwise, even before the PCR result.
Management
1. Infection prevention and control (start at once)
- Isolate the patient in a single room with dedicated equipment.
- Standard, contact and droplet precautions: gloves (double gloving for procedures), impermeable gown, mask (N95 for aerosol-generating procedures), face shield or goggles.
- Limit staff and procedures; safe sharps disposal; avoid unnecessary injections.
- Disinfect spills (for example with hypochlorite); safe handling of linen and waste.
- Safe burial of the dead with minimal handling of the body.
- Notify the district health office and public health authorities.
2. Supportive care (mainstay)
- Careful IV fluids, monitoring of vital signs, urine output and fluid balance.
- Blood products guided by bleeding and labs: platelets, fresh frozen plasma (or cryoprecipitate) and packed red cells.
- Paracetamol for fever; avoid aspirin, NSAIDs and IM injections.
- Proton pump inhibitor for GI protection.
- ICU care for shock, renal replacement therapy and ventilation as needed.
3. Antiviral
- Ribavirin (oral or IV) is widely used, especially when started early, in line with WHO and national guidance. The evidence of benefit is mixed, so it never replaces supportive care.
Livestock infected with CCHF virus look healthy, so a "healthy-looking" sacrificial animal does not rule out exposure.
- Side-effect to remember: haemolytic anaemia; avoid in pregnancy where possible (teratogenic).
The drug used against CCHF is ribavirin, a guanosine (purine nucleoside) analogue also used for hepatitis C, RSV and Lassa fever.
4. Exposed contacts and health workers
- Wash the exposed skin or wound with soap and water at once; irrigate mucosa.
- Record the exposure; monitor temperature twice daily for 14 days.
- Ribavirin prophylaxis is offered after high-risk exposure (for example a needle-stick from a confirmed case) in many protocols.
Prevention
- Tick control on animals (acaricides) and in animal sheds.
- Protective clothing (light-coloured long sleeves, gloves), repellents; check skin for ticks and remove them with tweezers, never crush with bare hands.
- Wear gloves and avoid contact with animal blood during slaughter; keep sacrificial animals out of homes.
- Infection control in hospitals.
- There is no widely approved vaccine.
Pakistan note: NIH Pakistan issues CCHF advisories before Eid ul-Adha covering case definitions, isolation, ribavirin use and contact follow-up. These are updated regularly, so always check the current national guidance.
"Tick, Tissue, Team": spread by tick bite, by animal tissue and blood, and to the health team.
Expect: the causative virus (Nairovirus) and its vector (Hyalomma tick); spread by tick bite, animal blood at slaughter and nosocomial contact; the Eid ul-Adha peak; phases and early severe bleeding; thrombocytopenia with raised liver enzymes and DIC; RT-PCR for early diagnosis; strict barrier nursing; ribavirin and its haemolytic side-effect; supportive care with blood products; distinguishing CCHF from dengue, malaria and leptospirosis.
Quick revision
- Nairovirus (Bunyavirales); Hyalomma tick; livestock amplify it without illness.
- Humans: tick bite, slaughter blood, patients' body fluids.
- Pakistan: Balochistan and KP; Eid ul-Adha peak.
- Incubation short: 1–3 days (tick), 5–6 days (blood).
- Sudden fever, myalgia → bruising and GI bleeding.
- Labs: low platelets, high AST/ALT, prolonged clotting.
- RT-PCR early; IgM after about day 5–7.
- Isolation and PPE; supportive care and blood products; ribavirin early.
Written by The House Job from standard references (Kumar and Clark's Clinical Medicine; Levinson's Review of Medical Microbiology and Immunology).
FAQ
How do people in Pakistan usually catch CCHF?
From the bite of an infected Hyalomma tick or from contact with the blood of infected animals, especially during handling and slaughter around Eid ul-Adha.
Is CCHF contagious between people?
Yes. It spreads through blood and body fluids, so health workers and carers need strict barrier precautions.
What is the best early test for CCHF?
RT-PCR on a blood sample in the first days of illness. IgM antibodies appear after about a week.
Which drug is used to treat CCHF?
Ribavirin, ideally started early, alongside supportive care and blood products. Its benefit is still debated, and it can cause haemolytic anaemia.