Download crimean-congo haemorrhagic fever

CRIMEAN-CONGO HAEMORRHAGIC FEVER (CCHF)
For 4th year student 2014
/ ‫ اسماعيل داود‬:‫دكتور‬
INTRODUCTION: Haemorrhagic fever cover a wide field in medicine (infectious
and non infectious) that cause fever associated with fever. The term viral
haemorrhagic fever is restricted to some groups of RNA viruses in which the fever is
associated with significant bleeding tendency in addition to the other features. These
groups and diseases caused by them is shown in the table below.
Crimean-Congo haemorrhagic fever: Is the only type of viral haemorrhagic fever
that was present in Iraq (the early cases were reported in late seventies and
subsequent cases were reported in eighties and early nineties of last century, then
disappeared till now), but awareness of the presence of such a disease here and there
in our country is still important.
HISTORY: ‫هذا المقطع لالطالع فقط‬
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. 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
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•
•
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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.
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.
The animals develop (little or no symptoms).
TRANSMISSION: 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, butchers and veterinarians.
CLINICAL MANIFESTATION
1. The incubation period is about 2 - 7 days, and has not been recorded as longer
than 12 days. The disease is more common in adult and older children than the small
children (more exposure to the source in adult). The disease is fatal during
pregnancy. It occurs mainly during hot seasons starting in late spring, summer, and
early autum, and rare during cold seasons like winter. This is because the life cycle
of tick and the virus life cycle in tick are affected by temperature variation.
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.
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
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.
Causes of shock in CCHF
1. Bleeding is the major cause
2. Dehydration due to vomiting and diarrhea
3. Occasionally immunological causes (Ag-Ab complex) leading to release of
mediators.
Causes of death in CCHF
1. Shock is the most important cause
2. Multiple organ failure
3. Renal failure
4. Secondary bacterial infection
5. Intra cranial haemorrhage
6. Respiratory distress syndrome
CONFIRMING THE DIAGNOSIS:
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 commonly-available cell lines such as monkey
kidney cells.
MANAGEMENT
1. 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)
2. INTENSIVE SUPPORTIVE MANAGEMENT
is required at an early stage and sometimes for prolonged periods by cases of CCHF.
The intensive Supportive management includes:
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.
3. OTHER MEASURES AND PROTECTING AGAINST HOSPITAL – ACQUIRED
CASES
1. Isolation of the patient in a single room in hospital
2. 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.
6. Send samples of blood for serological, CBC, blood group and Rh;
Labeling them as a “Highly infectious samples” to avoid Lab.
Personnel’s contamination.
7. Bone marrow examination may be needed sometimes to exclude blood diseases
like leukaemia.
8. A vaccine is not available 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: ‫هذا المقطع لالطالع فقط‬
1. Other non infectious diseases or conditions that need to be eliminated like
leukaemia, and aplastic anaemia.
2. Other infectious diseases that may be associated with haemorrhagic
manifestations like:
• Leptospirosis (spirochaetal disease)
• Listeriosis
Bacterial infections
• Meningococcal septicaemia
• Q fever
•
Other viral hemorrhagic fevers: Usually these are not present in our country
but may be present in other countries. These are also caused by RNA viruses
(look to the table below) and include:
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
Table 1: Shows different groups of RNA viruses that cause haemorrhagic fever: ‫هذه‬
‫الجداول لالطالع فقط‬
No
1
Viral group
Flaviviridae
2
Bunyaviridae
3
Arenaviridae
4
Filoviridae
Examples of the diseases
Yellow fever, dengue fever,
Omask HF, Kyasanar HF
Crimean-Congo HF, HF with renal
syndrome, rift valley HF
Lassa fever, Argentinean and
Bolivian HF
Murburge-Ebola HF
Table 2: Shows vector groups that are responsible for disease transmission in
different types of viral haemohhagic fever:
No
Vectors
Examples of Diseases
1
ARBO (Arthropod born)
Mosquito (Yellow fever, Dengue
fever,and Rift-valley fever).
Tick (CCHF, Omask HF,
Kyassar HF)
2
ROBA (Rodent born)
HF with renal syndrome, like
Argentina and Bolivian HF
3
Unknown vector
Murburge- Ebola Hf
)‫ (لالطالع فقط‬:‫تعليمات دفن الموتى بمرض الحمى النزفية‬
:‫لغرض منع انتشار الوباء لالخرين من المستحسن اجراء ما يلي عند الدفن‬
)‫م او اكثر‬2( ‫ ان يكون القبر بعمق مناسب‬.1
‫ ان توضع الجثة في تابوت محكم المنافذ ويستحسن ان يكون مصنوعا من حديد‬.2
‫ ان ترش على الجثة مادة معقمة وقاتلة للمكروبات‬.3
‫ من االفضل عدم السماح بنقل الجثة من مكان الى اخر ( من مدينة الى اخرى ) اال بعد مرور فترة زمنية مناتسبة‬.4
‫ ان تدفن الجثة تحت اشراف السلطات الصحية‬.5
‫ تحرق الشراشف والمالبس المستخدمة من قبل المريض في المستشفى‬.6