HAEMORRHAGIC FEVER

TRANSMITTED FROM ANIMALS TO THE HUMANBEING CCHF (RNA VIRUS ) IS ZOONETIC DISEASE TRANSMITTED FROM ANIMALS TO THE HUMANBEING

IT IS A VERY SERIOUS DISEASE AND NOTIFICATION TO HEALTH AUTHORATIES IS REQUISTED WITHIN 24 HOURS

HISTORY

During the summers of 1944 and 1945 over 200 cases of a severe, acute, febrile illness with marked hemorrhagic manifestations occurred in the USSR in the Western Crimea. Many of the cases were among troops of the Soviet Union. Virus was isolated from blood samples of patients with acute disease and from the tick Hyalomma. It was later realized that a similar disease had been known for many years in other areas of the USSR, particularly Central Asian republics, and the same syndrome has since been described in areas bordering the Black and Caspian Seas and Bulgaria and former Yugoslavia.

In 1969, it was shown that the virus causing CCHF was identical to the virus named Congo which had been isolated in 1956 from the blood of a febrile child in Zaire. This virus is widely spread in East and West Africa. More recently, CCHF or antibody to it, has been shown to have appeared in Dubai, Iraq, South Africa, Pakistan, Greece, Turkey, Albania, Afghanistan, and India. Geographical variation in virulence has been observed, for example, the disease in Africa, where haemorrhagic phenomena and deaths are only rarely reported, does not seem to be as virulent as in Asia.

Probably because CCIHF is associated with severe haemorrhagic features, secondary cases are relatively common. In an outbreak in Saudi Arabia, one case resuscitated in an accident and emergency unit gave rise to seven secondary cases. In 1967, five laboratory-acquired cases were recognized. Hospital-associated outbreaks were described in Pakistan in 1976 and in Dubai in 1980.

In November 1996, 15 cases of CCHF were confirmed in South Africa In November 1996, 15 cases of CCHF were confirmed in South Africa. All of the patients worked in the slaughtering unit of the same ostrich farm. Ostriches, like other birds, are thought to be fairly resistant to infection with CCHF, but they undoubtedly suffer heavy burdens of Hyalomma spp., which could be vectors of the disease.

VIROLOGY Name: CCHF VIRUS Genus: Nairovirus Family: Bunya virus (bunyaviridae) Type: RNA virus Vector: Tick Zoonosis: Transmitted from animals to human being.

CCHF RESERVOIRS AND VECTORS The CCHF virus may infect a wide range of domestic and wild animals. Many birds are resistant to infection, but ostriches are susceptible and may show a high prevalence of infection in endemic areas. Animals become infected with CCHF from the bite of infected ticks. A number of tick genera are capable of becoming infected with CCHF virus, but the most efficient and common vectors for CCHF appear to be members of the Hyalomma genus. Trans-ovarial (transmission of the virus from infected female ticks to offspring via eggs) and venereal transmission have been demonstrated amongst some vector species, indicating one mechanism which may contribute to maintaining the circulation of the virus in nature.

Once infected, the tick remains infected through its developmental stages, and the mature tick may transmit the infection to large vertebrates, such as livestock. Domestic ruminant animals, such as cattle, sheep and goats, are viraemic (virus circulating in the bloodstream) for around one week after becoming infected. (little or no symptoms). Humans who become infected with CCHF acquire the virus from direct contact with blood or other infected tissues from livestock during this time, or they may become infected from a tick bite. The majority of cases have occurred in those involved with the livestock industry, such as agricultural workers, slaughterhouse workers and veterinarians.

CLINICAL MANIFESTATION 1. The incubation period is about 2 - 7 days, and has not been recorded as longer than 12 days. 2. Prodromal stage: Illness begins abruptly with High fever, Myalgia, Headache, Vomiting Pain in the epigastrium, lower back and thighs. Loose stools, dry cough, tachycardia, although relative bradycardia may be present.

3. Haemorrhagic manifestation: Some patients recover quite suddenly after seven or eight days, but up to 75% begin to show haemorrhagic features after 3 - 5 days. Petechial rashs often appears in the mucous members and skin Ecchymosis ( blue and black patches) in skin Haematemesis and melaena Epistaxis Conjunctival injection and haemorrhages Haematuria. Despite high viraemia, there is often a marked neutrophilia.

Two images of Crimean-Congo Hemorrhagic Fever patients taken in 1969 showing the characteristic dark patches on the skin.

4. Other features and complications: The liver is enlarged and tender, liver and tissue transaminases are elevated and disseminated intravascular coagulation (DIC) may follow. Death may occur (30 -50% of cases) on the seventh to ninth day, following a period of shock, oliguria and, sometimes, respiratory distress syndrome. Leucopenia and thrombocytopenia

5. Convalescence: The patient may recover gradually, starting on day 10 onwards. The skin rashes (petechia and ecchymosis) fade, bleeding stops and fever subsides. The recovery is usually complete, although some describe a type of neuritis and asthenia which may remain for some time. The patient is usually less infectious and even in late days of this stage is non infectious, and his serum can be used for prophylaxis (passive immunity) for contacts in future. The immunity is permanent for all strains of CCHF viruses. The patient remains in hospital for an average of 20 days.

Causes of bleeding in CCHF Generalized capillary damage is the major cause. Rarely DIC may occur in severe conditions, late in the disease; may play a role as indicated by prolonged PT, PTT and increase in fibrin degradation products (FDP). Thrombocytopenia is usually mild and usually not plays an important role in bleeding.

Causes of shock in CCHF Bleeding is the major cause Dehydration due to vomiting and diarrhea Occasionally immunological causes (Ag-Ab complex) leading to release of mediators.

Causes of death in CCHF Shock is the most important cause Multiple organ failure Renal failure Secondary bacterial infection Intra cranial haemorrhage Respiratory distress syndrome

Early diagnosis is possible using Antigen detection by immunofluorescence techniques. Some laboratories use reverse transcriptase PCR methods. Antibody detection: by using immunofluorescence test and ELIZA test IgM antibodies are often detectable after the first five to seven days of fever, but their concentration diminishes significantly after about 10 days, and is replaced by rising IgG levels. 3.The virus is readily cultured in commonly-available cell lines such as monkey kidney cells.

Specific treatment: There is evidence that CCHF responds to treatment with ribavirin amelioration of fever and lessening or avoidance of haemorrhagic features. The use of ribavirin is complicated in these patients by its tendency to cause significant anaemia, mainly due to haemolysis. (also can be given to contacts) Intensive supportive management is required at an early stage and sometimes for prolonged periods by cases of CCHF.

Supportive treatment: Correction of dehydration, electrolytes, and blood transfusion. Monitoring of the patient and follow up chart. Treatment of DIC. Routine steroid and antibiotics are not indicated. Management of other complications if present.

Other measures and protecting against hospital-acquired cases: Isolation of the patient in a single room in hospital Decrease the number visitors and medical personnel to the patient 3. provision of adequate disposable equipment and protection clothing. 4. Notification of the disease to health authorities within 24 hours.

5. Good staff training and supervision 6. Regular observation of all contacts for any symptom; samples of blood may be taken from them for serology. 7 . Send samples of blood for serological, CBC, blood group and Rh; labelling them as “Highly infectious samples” 8. Bone marrow Exam. May be done sometimes to exclude other causes. 9. A vaccin is not avaliable for CCHF at time being.

Decontamination: The virus is killed by common disinfectants, solvents, and dry heat (56°C, 30 min.). The vectors (ticks of the genus Hyalomma) also need to be controlled with acaricides and possible animal reservoirs will need to be monitored.  

Differential Diagnosis Other disease or conditions that need to be eliminated Other infectious diseasesOther problems Leptospirosis Listeriosis Q fever Other viral hemorrhagic fevers Argentinian hemorrhagic fever Bolivian hemorrhagic fever Dengue fever Ebola hemorrhagic fever Hemorrhagic fever with renal syndrome Lassa fever Marburg fever Rift valley fever Yellow fever