What is Marburg hemorrhagic fever?
Marburg hemorrhagic fever is caused by a filovirus. Filoviruses are separated into two distinct types, Marburg and Ebola. All filoviruses are classified as biosafety level 4 agents based on their high mortality rate, potential transmissibility, and the absence of effective vaccines or treatments. The systemic nature of filovirus infections suggest they may have immunosuppressive effects.
Human-infecting viruses usually appear as small, round, or oval organisms. Filoviruses are unique among human viruses, appearing as long, cylindrical organisms with twists and loops. The natural reservoir for filoviruses is unknown but is presumed to be wild animals (zoonotic). Research suggests that filoviruses may possibly be linked to fruit bats, from which the viruses are occasionally introduced into primate populations. The primary transmission of Marburg filovirus from its natural reservoir appears to occur only in sub-Saharan Africa within five degrees of the equator.
Human transmission of Marburg hemorrhagic fever is by direct contact with infected blood, semen, urine, mucus, and organs. Some evidence suggests that aerosol transmission may also occur. The virus enters the body through lesions and initially infects the lymph nodes, spleen, and liver. Marburg filovirus can survive several weeks in corpses and blood samples.
The incubation period of Marburg hemorrhagic fever is two to twenty-one days after infection, and symptoms include high fever, severe headache, painful sore throat, rashes, muscle pain (myalgia), inflamed lymph nodes, dementia, and bloody vomiting and diarrhea from internal hemorrhaging. Symptoms usually progress to bleeding from the gums and nose, puncture openings in the skin, small hemorrhages in the whites of the eyes, and eventual red blood cell immobilization. Hair, skin, and nail loss, as well as searing body pain from inflamed nerves, occur in later stages of infection. The infection may last as long as three weeks and is often described as agonizing. In fatal cases, the patient’s blood pressure undergoes a final severe drop resulting in shock prior to death.
There is no vaccine or specific therapy available for filoviral infections, although several vaccines and drug therapies are currently being tested. Specific symptoms are treated during the course of infection; the patient either responds or does not. Secondary prevention requires total isolation of infected patients. Primary infected patients show a higher mortality rate than do secondary infected patients. The mortality rate for humans infected with Marburg hemorrhagic fever ranges from 24 to 88 percent, with some outbreaks being more deadly than others.
Marburg hemorrhagic fever was first described in 1967 during outbreaks at research laboratories in Marburg and Frankfurt, Germany, and Belgrade, Yugoslavia, and linked to African green monkeys imported for research purposes from Uganda. Since the initial outbreaks, sporadic cases of Marburg hemorrhagic fever have been identified in eastern and southern Africa, with the largest outbreaks occurring in the Democratic Republic of the Congo in 1998 and in Uganda in 2012. One of the most frightening aspects of Marburg hemorrhagic fever is its ongoing inclusion in some nations’ biological weapons programs.
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