Crimean Congo Haemorrhagic Fever (CCHF) – What you need to know

The federal health authorities are on a high alert after the reported outbreak of Crimean Congo haemorrhagic fever (CCHF) in Karachi and are maintaining a continuous contact with the provincial health department. Hospitals in Karachi were put on alert on Friday after CCHF was confirmed to have killed five people including a lady doctor in six weeks and infected over 40. (As reported in news)

Crimean-Congo hemorrhagic fever (CCHF) is an infectious and potentially lethal disease caused by a Nairovirus. The disease was first described in the Crimea in 1944 and given the name Crimean hemorrhagic fever.
In 1969, it was recognized that the pathogen causing Crimean haemorrhagic fever was the same as that responsible for an illness identified in 1956 in the Congo and linkage of the 2 place names resulted in the current name for the disease and the virus.

CCHF is a severe disease in humans, with a high mortality rate. Fortunately, human illness occurs infrequently, although animal infection may be more common.

Evidence of Crimean-Congo hemorrhagic fever has been found in Africa, Asia, the Middle East and Eastern Europe.

Mode of Infection
The viruses are transmitted to the animals by (Hyalomma) ticks. CCHF, is the most important human pathogen amongst them.

The most important source for acquisition of the virus by ticks is believed to be infected small vertebrates on which immature Hyalomma ticks feed. Once infected, the tick remains infected through its developmental stages, and the mature tick may transmit the infection to large vertebrates, such as livestock.

The bite of CCHF virus carrying ticks may infect a wide range of domestic and wild animals. Specially animals, such as cattle, sheep and goats. Virus remains circulating in the bloodstream of the animals for around one week after becoming infected. Many birds are resistant to infection, but ostriches are susceptible and may show a high prevalence of infection in endemic areas.

Possible methods of Human Infection
A bite from an infected tick.

Direct Contact with blood or tissues from infected livestock. People, who work with animals, suchas agricultural workers, slaughterhouse workers veterinarians, are at increased risk.

Accidental inoculation with infected blood; for example, a health care professional may prick their finger while taking a blood sample from a patient.

Clinical features
The appearance of symptoms after becoming infected (incubation period) depends on the mode of acquisition of the virus. Following infection via tick bite, the incubation period is usually one to three days, with a maximum of nine days.

Fever

Aching muscles,

Dizziness

Neck pain and stiffness

Backache

Headache

Sore eyes and photophobia (sensitivity to light).

Stages of Attack:
There may be nausea, vomiting and sore throat early on, which may be accompanied by diarrhea and generalized abdominal pain.

Over the next few days, the patient may experience sharp mood swings, and may become confused and aggressive. After two to four days, the agitation may be replaced by sleepiness, depression and lassitude, and the abdominal pain may localize to the right upper abdomen, with detectable liver enlargement.

Other clinical signs, which emerge, include fast heart rate, enlarged lymph nodes, rashes caused by bleeding into the skin; these rashes could be inside the mouth and throat, and on the skin. These rashes may give way to bleeding from the upper bowel, causing blood in the faeces; there may be blood in the urine, nosebleeds and bleeding from the gums. There is usually evidence of hepatitis. The severely ill may develop liver, kidney and pulmonary failure after the fifth day of illness.

The mortality rate from CHF is approximately 30%, with death occurring in the second week of illness.

In those patients who recover, improvement generally begins on the ninth or tenth day after the onset of illness.

Diagnosis

Diagnosis of suspected CCHF is performed in specially equipped, high bio safety level laboratories.

Antibodies may be detected in serum from about day six of illness.

One of the antibodies (IgM) remains detectable for up to four months, and another (IgG) levels decline but remain detectable for up to five years.

Patients with fatal disease do not usually develop a measurable antibody response and in these individuals, as well as in patients in the first few days of illness, diagnosis is achieved by virus detection in blood or tissue samples.

Prevention and control
Although an inactivated vaccine against CCHF has been developed and used on a small scale in Eastern Europe, there is no safe and effective vaccine widely available for human use.

The tick vectors are numerous and widespread and tick control with chemicals intended to kill ticks is only a realistic option for well-managed livestock production facilities.

Persons living in endemic areas should use personal protective measures that include avoidance of areas where tick vectors are abundant and when they are active (spring to autumn); regular examination of clothing and skin for ticks, and their removal; and use of repellents.

Persons who work with livestock or other animals in the endemic areas can take practical measures to protect themselves. These include the use of repellents on the skin and clothing and wearing gloves or other protective clothing to prevent skin contact with infected tissue or blood.

When patients with CHF are admitted to hospital, there is a risk of hospital-acquired spread of infection. In the past, serious outbreaks have occurred in this way and it is imperative that adequate infection control measures be observed to prevent this disastrous outcome.

Patients with suspected or confirmed CHF should be isolated and cared for using barrier-nursing techniques. Specimens of blood or tissues taken for diagnostic purposes should be collected and handled using universal precautions. Sharps (needles and other penetrating surgical instruments) and body wastes should be safely disposed of using appropriate decontamination procedures.

Healthcare workers who have had contact with tissue or blood from patients with suspected or confirmed CHF should be followed up with daily temperature and symptom monitoring for at least 14 days after exposure.

Treatment includes antiviral medicines and isolated intensive care.

Source of Information: © World Health Organization 2005.

1 Comment so far

  1. Syed Muhammad Nabeel (unregistered) on December 1st, 2005 @ 11:39 am

    How could the outbreak be stopped and how much time it will take??
    May Allah protect us from the deadly infection ……



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