Marburg virus disease is a rare but severe hemorrhagic fever that can cause significant illness in humans. This disease is related to the Ebola virus, belonging to the same family of viruses. An outbreak of Marburg virus was confirmed in Tanzania in 2023, drawing international attention to this serious health concern.
The Outbreak in Tanzania’s Kagera Region
The Ministry of Health of Tanzania declared its first Marburg virus disease outbreak on March 21, 2023. This event occurred in the Kagera region, in the Bukoba district of the northwest. Between the declaration date and May 31, a total of nine cases were reported, eight laboratory-confirmed and one probable case. The outbreak resulted in six fatalities, with a 67% case fatality ratio.
The last confirmed case was reported on April 11, 2023, with the outbreak declared over on June 2, 2023. This declaration followed World Health Organization recommendations, occurring 42 days after the last possible exposure to a confirmed or probable case. The public health response in Kagera involved developing a national plan and deploying a rapid response team for investigation and containment.
Symptoms and Progression of Marburg Virus
The incubation period for Marburg virus disease, the time from infection to symptom onset, ranges from two to 21 days. The illness begins abruptly with initial symptoms such as high fever, severe headache, profound malaise, and muscle aches. Around the fifth day after symptom onset, patients may develop a maculopapular rash, noticeable on the trunk.
As the disease progresses, severe gastrointestinal symptoms can appear, including watery diarrhea, abdominal pain, cramping, nausea, and vomiting. Hemorrhagic manifestations, such as blood in vomit, feces, nose, gums, or vagina, may appear from day five. In fatal cases, death occurs between eight and nine days after symptoms begin, often preceded by blood loss and shock. The case fatality rate varies from 24% to 90% depending on the specific virus strain and the availability of supportive care.
How the Virus Spreads
Marburg virus spreads through two pathways. Initial human infection often arises from animal exposure, with the African fruit bat, Rousettus aegyptiacus, the natural host. Infection can occur through prolonged exposure in mines or caves inhabited by fruit bat colonies.
After animal-to-human transmission, the virus can spread between humans. Human-to-human transmission occurs through direct contact with blood, secretions, organs, or other bodily fluids of infected individuals. Contact with contaminated surfaces and materials, like bedding or clothing, also facilitates transmission. Marburg virus is not airborne. Burial ceremonies involving direct contact with the deceased can also contribute to spread.
Containment and Treatment Measures
Controlling Marburg virus outbreaks relies on public health interventions. Rapid case identification and isolation of suspected or confirmed patients in designated treatment centers prevent further spread within households and communities. Contact tracing monitors individuals who may have been exposed.
Safe burial practices for deceased individuals also prevent post-mortem transmission. No approved antiviral drugs or vaccines exist for Marburg virus disease. Patient care involves supportive measures, focusing on rehydration with oral or intravenous fluids and managing symptoms. Early and intensive supportive care can improve a patient’s chances of survival.