Health Tips
August 22, 2019
Congo Crimean Hemorrhagic Fever - Urdu Books World
Key facts
- The Congo-Crimean hemorrhagic fever virus (CCHF) virus causes a series of outbreaks of viral hemorrhagic fever.
- The mortality rate during outbreaks of CCHF reaches 40%.
- The virus is transmitted to humans, mainly from ticks and livestock. Transmission from person to person can occur as a result of close contact with the blood, secretions, organs, or other body fluids of infected people.
- CCHF is endemic in Africa, the Balkans, the Middle East and Asia, in countries south of the 50th parallel of north latitude.
- There is no vaccine for humans or animals.
Congo-Crimean hemorrhagic fever (CCHF) is a widespread
disease caused by the tick-borne virus (Nairovirus) of the Bunyaviridae family.
CCHF virus causes outbreaks of severe viral hemorrhagic fever with a mortality
rate of 10-40%.
CCHF is endemic in Africa, the Balkans, the Middle East and Asian countries south of the 50th parallel of northern latitude - the geographical border of the distribution of ticks, which is the main carrier.
Congo-Crimean hemorrhagic fever virus in animals and ticks.
CCHF virus carriers include a wide range of wild and
domestic animals such as cattle, sheep and goats. Many birds are resistant to
this infection, but ostriches are susceptible to it, and among them there may
be high rates of infection in endemic areas where they are the source of
infection in cases of human disease. For example, one of the past outbreaks of
the disease occurred at an ostrich slaughter in South Africa. There are no obvious
signs of disease in these animals.
Animals become infected by being bitten by infected ticks,
and the virus remains in their bloodstream for approximately one week after
infection, which, with subsequent tick bites, ensures the continuation of the tick-animal-tick
cycle. Although several types of ticks can become infected with the CCHF virus,
the main carriers are ticks of the Hyalomma species.
Transmission of infection
CCHF virus is transmitted to humans either by tick bites or
by contact with infected blood or animal tissues during and immediately after
slaughter. Most cases of infection occur in people employed in livestock
farming, such as farm workers, slaughterhouse workers and veterinarians.
Transmission from person to person can occur as a result of
close contact with the blood, secretions, organs, or other body fluids of
infected people. Cases of nosocomial infection may also occur as a result of
inadequate sterilization of medical equipment, reuse of needles and
contamination of medical supplies.
Signs and Symptoms
The duration of the incubation period depends on the method
of infection with the virus. After infection by a tick bite, the incubation
period usually lasts one to three days, with a maximum duration of nine days.
The incubation period after contact with infected blood or tissues usually
lasts five to six days with a documented maximum period of 13 days.
Symptoms appear suddenly with fever, myalgia (muscle pain),
dizziness, pain and stiffness of the neck, back or lower back pain, headache,
inflammation of the eyes and photophobia (sensitivity to light). Nausea,
vomiting, diarrhea, pain in the abdomen and sore throat can be observed,
followed by sudden mood swings and confusion. After two to four days,
excitement can be replaced by drowsiness, depression and fatigue, and pain in
the abdomen can be localized in the upper right part with detectable
hepatomegaly (enlarged liver).
Other clinical signs include tachycardia (palpitations),
lymphadenopathy (swollen lymph nodes), and a petechial rash (a rash caused by
bleeding into the skin) on the inside of the mucous membranes, such as in the
mouth and throat, as well as on the skin. The petechial rash can go into a
larger rash called ecchymosis, and other hemorrhagic events. Symptoms of hepatitis
are usually observed, and after the fifth day of illness in seriously ill
patients, there may be a rapid deterioration in kidney function and sudden
liver or pulmonary failure.
The mortality rate from CCHF is approximately 30%, with
death occurring in the second week of the disease. In recovering patients,
improvement usually begins on the ninth or tenth day after the onset of the
disease.
Diagnostics
CCHF virus infection can be diagnosed with several different laboratory tests:
- Enzyme immunoassay (ELISA);
- Detection of antigens;
- Serum neutralization;
- Reverse transcriptase polymerase chain reaction (RT-PCR);
- Virus isolation in cell cultures.
In terminally ill patients, as well as patients in the first
few days of the disease, measurable antibody formation usually does not occur,
therefore, diagnosis in such patients is carried out by detecting the virus or
RNA in blood or tissue samples.
Testing patient samples presents an extremely high
biological risk and should only be carried out under conditions of maximum
biosafety. However, if samples are inactivated (e.g., by viricides, gamma
radiation, formaldehyde, exposure to high temperatures, etc.), they can be
handled under basic biosafety conditions.
Treatment
The main approach to managing CCHF in humans is conventional
supportive care with symptom management.
The antiviral drug ribavirin leads to obvious positive
results in the treatment of CCHF infection. Both oral and intravenous dosage
forms are effective.
Disease Prevention and Control
Fight against CCHF among animals and ticks
Robert Swanepoel / NICD South Africa
It is difficult to prevent and control CCHF infection among
animals and ticks, because the tick-animal-tick cycle usually goes unnoticed
and the infection in domestic animals usually proceeds without obvious signs.
In addition, tick-borne ticks are numerous and widespread, so the only
practical option for properly managed livestock enterprises is to control ticks
with acaricides (chemicals used to kill ticks). For example, after an outbreak
of the disease in an ostrich slaughter in South Africa (mentioned above),
measures were taken to ensure that ostriches remained in the quarantine free
from ticks for 14 days before slaughter. This measure helped to reduce the risk
that the animal was infected during slaughter and prevent the infection of
people in contact with animals.
Reducing the risk of human infection
Although an inactivated vaccine derived from mouse brain
tissue has been developed against CCHF that has been used on a small scale in
Eastern Europe, there is currently no safe and effective vaccine for widespread
use in humans.
In the absence of a vaccine, the only way to reduce the
number of infections among people is to raise awareness of risk factors and
educate people about the measures they can take to limit exposure to the virus.
Public health recommendations should focus on several
aspects.
- Reducing the risk of transmission of the virus from ticks to humans:
- Wear protective clothing (long sleeves, long trousers);
- Wear light-colored clothing that makes it easy to spot ticks on clothing;
- Apply approved acaricides (chemicals used to kill ticks) for clothing;
- Apply approved repellents to skin and clothing;
- Regularly inspect clothing and skin for ticks; if they are detected, remove them using safe methods;
- To strive to prevent the defeat of animals by ticks or to fight against ticks in rooms for keeping animals;
- Avoid staying in areas where there are a large number of ticks, and in those seasons when they are most active.
- Reducing the risk of transmission of the virus from animals to humans:
- Keep animals in quarantine before they enter the slaughterhouse or treat the animals with pesticides in the usual manner two weeks before slaughter.
- Reducing the risk of transmission from person to person in selected communities:
- Avoid close physical contact with people infected with CCHF;
- Wear gloves and protective clothing when caring for sick people;
- Wash your hands regularly after caring for or visiting sick people.
Infection control in medical facilities
Health care providers who care for patients with suspected
or confirmed CCHF, or who work with samples taken from them, must follow
standard infection control measures. These include basic hand hygiene, personal
protective equipment, safe injection practices and safe burial practices.
As a precautionary measure, healthcare providers who care
for patients directly outside the CCHF outbreak area should also follow
standard infection control measures.
Samples taken from people with a proposed CCHF should be handled
by specially trained staff working in properly equipped laboratories.
Recommendations for infection control in the process of
assisting patients with suspected or confirmed Congo-Crimean hemorrhagic fever
should be consistent with the WHO recommendations developed for Ebola and
Marburg hemorrhagic fevers.
WHO activities
WHO works with partners to support CCHF surveillance,
diagnostic capacity and outbreak response in Europe, the Middle East, Asia and
Africa.
WHO also provides documentation to facilitate research and
control of the disease and has developed a memo on standard precautions in
medical settings that is designed to reduce the risk of transmission of
bloodborne pathogens and other pathogens.
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