Transcript cchf (rna virus )

HAEMORRHAGIC FEVER
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CCHF (RNA VIRUS )
IS ZOONETIC DISEASE
TRANSMITTED FROM
ANIMALS TO THE
HUMANBEING
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IT IS A VERY SERIOUS
DISEASE AND
NOTIFICATION TO HEALTH
AUTHORATIES IS
REQUISTED WITHIN 24
HOURS
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HISTORY
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• 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.
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• 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.
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• 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.
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• 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.
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VIROLOGY
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Name: CCHF VIRUS
Genus: Nairovirus
Family: Bunya virus (bunyaviridae)
Type: RNA virus
Vector: Tick
Zoonosis: Transmitted from animals to
human being.
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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.
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• 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.
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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.
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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.
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Two images of Crimean-Congo Hemorrhagic
Fever patients taken in 1969 showing the
characteristic dark patches on the skin.
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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
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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.
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Causes of bleeding in CCHF
1. Generalized capillary damage is the
major cause.
2. 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).
3. Thrombocytopenia is usually mild and
usually not plays an important role in
bleeding.
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Causes of shock in CCHF
1. Bleeding is the major cause
2. Dehydration due to vomiting and
diarrhea
3. Occasionally immunological causes (AgAb complex) leading to release of
mediators.
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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
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Early diagnosis is possible using
1. Antigen detection by immunofluorescence
techniques. Some laboratories use reverse
transcriptase PCR methods.
2. 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 commonlyavailable cell lines such as monkey kidney
cells.
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• 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.
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• Supportive treatment:
1. Correction of dehydration, electrolytes,
and blood transfusion.
2. Monitoring of the patient and follow up
chart.
3. Treatment of DIC.
4. Routine steroid and antibiotics are not
indicated.
5. Management of other complications if
present.
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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
provision of adequate disposable
equipment
and protection clothing.
Notification of the disease to health
authorities within 24 hours.
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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.
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• 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.
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Differential Diagnosis
Other disease or conditions that need to be eliminated
Other infectious diseasesOther problems
Leptospirosis
Listeriosis
Q fever
Other viral hemorrhagic fevers
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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
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