Credit CDC
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In 1967, several workers involved with Polio research at a laboratory in Marburg, Germany fell ill with an unknown illness. What began with fever, vomiting, and diarrhea progressed rapidly to internal bleeding, shock, and for 7 of the 31 victims, death.
An investigation identified the source of the virus; Green monkeys imported from Uganda for research. We now know that while monkeys and other mammals can be infected, the reservoir host of Marburg virus is the African fruit bat, Rousettus aegyptiacus.
This led to the creation of a new virus family; the Filoviridae, of which Marburg and the six known Ebola viruses are the principal members.
While less common than Ebola, since 2021 we've seen a uptick in outbreaks - with cases being reported by 5 new African nations (see recent reports from Equatorial Guinea, Guinea, Tanzania, Rwanda, and Ghana).
Tanzania reported their first outbreak in March of 2023, which was resolved relatively quickly (May 30th), with 8 confirmed and 1 probable cases, and 5 deaths.
Neighboring Rwanda, which saw an outbreak beginning last September and declared over in December, produced 66 confirmed cases and 15 deaths.
Last yesterday the WHO published their initial DON report on Tanzania's 2nd (suspected) Marburg outbreak. Due to its length, I've only posted some excerpts. Follow the link to read it in its entirety.
Outbreak of suspected Marburg Virus Disease - United Republic of Tanzania
14 January 2025
Description of the situation
Introduction
On 13 January 2025, WHO informed its Member States and IHR State Parties of an outbreak of suspected Marburg Virus Disease (MVD) in the Kagera region of the United Republic of Tanzania using our secure web-based platform—the Event Information Site (EIS). Under the International Health Regulations, the EIS is used to issue rapid alerts to Member States of acute and rapidly developing public health risks and events with possible international implications.
Summary of the situation
On 10 January 2025, WHO received reliable reports from in-country sources regarding suspected cases of MVD in the Kagera region of the United Republic of Tanzania. Six people were reported to have been affected, five of whom had died. The cases presented with similar symptoms of headache, high fever, back pain, diarrhoea, haematemesis (vomiting with blood), malaise (body weakness) and, at a later stage of disease, external haemorrhage (bleeding from orifices).
As of 11 January 2025, nine suspected cases were reported including eight deaths (case fatality ratio (CFR) of 89%) across two districts – Biharamulo and Muleba. Samples from two patients have been collected and tested by the National Public Health Laboratory. Results are pending official confirmation. Contacts, including healthcare workers, are reported to have been identified and under follow-up in both districts.
The Bukoba district in Kagera region experienced its first MVD outbreak in March 2023, and zoonotic reservoirs, such as fruit bats, remain endemic to the area. The outbreak in March 2023 lasted for nearly two months with nine cases including six deaths.
Public health response
National rapid response teams have been deployed to support outbreak investigation and response; surveillance activities have been intensified with contact tracing ongoing; laboratory samples from recent cases have been sent for confirmation at the National Public Health Laboratory. A mobile laboratory is located in Kagera region and treatment units have reportedly been established.
WHO risk assessment
The risk of this suspected MVD outbreak is assessed as high at the national level due to several concerning factors. The suspected outbreak thus far involves at least nine suspected cases, including eight deaths, resulting in a high CFR of 89%. Healthcare workers are included among the suspected cases affected, highlighting the risk of nosocomial transmission. The source of the outbreak is currently unknown.
The reporting of suspected MVD cases from two districts suggests geographic spread. The delayed detection and isolation of cases, coupled with ongoing contact tracing, indicates lack of a full information of the current outbreak. More cases are expected to be identified.
The regional risk is considered high due to Kagera region's strategic location as a transit hub, with significant cross-border movement of the population to Rwanda, Uganda, Burundi and the Democratic Republic of the Congo. Reportedly, some of the suspected cases are in districts near international borders, highlighting the potential for spread into neighbouring countries. MVD is not easily transmissible (i.e. in most instances, it requires contact with the body fluids of a sick patient presenting with symptoms or with surfaces contaminated with these fluids). However, it cannot be excluded that a person exposed to the virus may be travelling.
The global risk is currently assessed as low. There is no confirmed international spread at this stage, although there are concerns about potential risks. Kagera region, while not close to Tanzania's capital or major international airports, is well-connected through transportation networks, and has an airport that connects to Dar es Salaam for onward travel outside Tanzania by air. This highlights the need for enhanced surveillance and case management capacities at relevant points of entry and borders, and close coordination with neighbouring countries to strengthen readiness capacities.
Although most cases have been restricted to central Africa, a few cases have been exported, via humans or lab animals, to other regions (see EID Journal Response to Imported Case of Marburg Hemorrhagic Fever, the Netherlands).
In 2019 the CDC released a list of the 56 zoonotic diseases of greatest concern to the United States, and while Ebola came in at number 16, Marburg was much further down the list at #38.
While history suggests that most VHF (Viral Hemorrhagic Fever) outbreaks are local events, ten years ago an outbreak of Ebola in Western Africa - one that spread across 3 nations, lasted nearly 2 years, and infected tens of thousands - is a reminder why we should ever underestimate these viruses.
