OVERVIEW
Omsk hemorrhagic fever is an acute febrile illness characterized by viral antigens, natural epidemiology, hemorrhagic symptoms, and a benign course.The disease was identified in 1941-1943 and was first reported in the rural areas north of Omsk in Siberia, the former Soviet Union, in 1944-1945.The two outbreaks of Omsk hemorrhagic fever in 1945 and 1946 had an incidence of more than 200 people and 600 people, respectively. In 1945 and 1946, two outbreaks of Omsk hemorrhagic fever affected more than 200 and 600 people respectively.
Causes
1.Omsk hemorrhagic fever virus
Omsk hemorrhagic fever virus belongs to the genus Flavivirus. It is single-stranded ribonucleic acid (RNA). The virus mainly invades the blood vessels and nervous system. This virus can be isolated from the blood of patients and striped ticks in the acute stage.
2. Skin, mucous membranes and visceral vessels
There is congestion and endothelial cell damage, which increases vascular permeability and produces tissue congestion and edema.
3. Decreased vascular tone
It can lead to defecation and shock.
4. Cerebral edema
May cause sensory changes.
Symptoms
The incubation period of the disease is usually 1 to 10 days. The disease is characterized by congestion of the skin and mucous membranes. The disease usually starts suddenly and is accompanied by pain in the extremities, vomiting and diarrhea, fever, headache, and bleeding from the nose, intestines, lungs, and uterus. A second fever, much more severe than the first, is possible and usually occurs within 10 to 15 days of the onset of the disease. Meningeal symptoms, pneumonia and kidney disease may also accompany the second fever.
Examination
1. Blood tests
Leukocytes and platelets are decreased and plasma cells are increased in the acute phase. The cell count and protein in the cerebrospinal fluid may be elevated in meningeal involvement.
2. Urine routine examination
Clear protein and granulocyte tubular pattern can be detected in urine.
3. Virus isolation
Isolation of the virus from patients in the acute phase and detection of antibodies by virus neutralization tests are valuable for diagnosis.
Diagnosis
Diagnosis is generally made by taking blood and cerebrospinal fluid from patients within one week and inoculating them with guinea pig, mouse brain or chicken embryo for virus isolation, or by taking double serum for complement binding or neutralization test, which is more than 4-fold elevated.
Differential diagnosis
1. Early stage of fever
It should be differentiated from regression fever, typhoid fever, spotted fever, leptospirosis and so on. For example, the basic pathological features of typhoid fever are persistent bacteremia, involvement of the mononuclear-phagocytic system, tiny abscesses and small ulcer formation in the distal ileum. Typical clinical manifestations include persistent high fever, apathy, abdominal discomfort, hepatosplenomegaly.
2. Hemorrhagic stage
It should be distinguished from epidemic hemorrhagic fever and epidemic encephalitis. For example, the typical manifestations of “epidemic encephalitis” are acute onset of high fever, headache, vomiting, skin and mucous membrane petechiae and meningeal irritation.
Complications
Meningeal symptoms, pneumonia and kidney disease may occur.
Treatment
Supportive and symptomatic treatment, including correction of hypotension, pain relief, dehydration and hemorrhage, is usually the mainstay of treatment.