I have previously written about the Marburg virus, the timeline and history of outbreaks, and the recent outbreak in Rwanda. This is an update. Marburg virus is one of the deadliest viruses known to infect humans. Much of the background information below comes from “Key information about Rwanda’s deadly Marburg outbreak is still missing” https://www.science.org/content/article/key-information-about-rwanda-s-deadly-marburg-outbreak-still-missing.
This is the first outbreak of Marburg virus disease in Rwanda. It was announced on September 27, 2024 after the virus was detected in a blood specimen the day before. It is common for infectious disease outbreaks in African countries to be dismissed as inconsequential to those living in the U.S. But, time and time again, history should have taught us that this is flawed thinking. Human immunodeficiency virus, Ebola virus, and Monkeypox virus are just three viruses off the top of my head that first began as isolated outbreaks in Africa, but then caused disease to appear in the United States, with HIV and MPox being the largest in scale. In large part, this is due to the large amount of international travel and the long incubation periods of these viruses.
Instead, what we should have learned is that Africa is a great laboratory for us to learn about emerging pathogens (to give credit to the CDC, we do have CDC workers stationed in Africa) and that even if we don’t do it for altruistic reasons, researching these organisms, developing therapeutics and vaccines, and assisting Africa to contain these outbreaks is in our best interest to avoid the much more difficult and expensive undertaking of containing disease outbreaks in the U.S. and the rest of the world.
We refer to the first known case of an outbreak as the “index” case. Identifying the index case of a novel or rare virus infection, especially when the infection transmission is zoonotic (transmitted from an animal to the human), when possible is extremely helpful because the epidemiological links are fewer with a greater opportunity to discover when the first infection likely occurred and what the potential sources of that infection were.
In the case of this outbreak, we have little information about the index case, but we have some. First, it was an adult male. Second, he died from the infection on September 8. Third, the wife did not become infected after observation for a full incubation period (up to 21 days).
Piecing together information from reliable, but unofficial sources, we learn that the index case had traveled in Rwanda prior to falling ill. He was treated at King Faisal Hospital in Kigali (a very good hospital, especially for these tropical diseases). He actually (as have been several other subsequent cases) was co-infected with malaria and Marburg virus. Doctors diagnosed the malaria, which they commonly see, but did not realize that he also was infected with the Marburg virus as this virus had never been detected in Rwanda before and early signs and symptoms of these two infections overlap, thus, the malaria diagnosis appeared to explain the index case’s illness.
It was only after several health care workers from the hospital’s intensive care unit became ill that the concern for a spreading hemorrhagic fever illness grew (malaria is not transmitted from human-to-human). Tests subsequently confirmed that the index patient had Marburg virus disease (MVD).
Most of the cases in this outbreak are in health care workers. Infected health care workers likely also infected more health care workers. It is possible that some people were been exposed to the virus from contact with the dead body of the index case and at the funeral.
Concerningly, there are some infected in this outbreak who have not been able to be traced to another known infected person. That suggests that some cases of infection have likely been missed.
Health care workers are at especially high risk for transmission of this virus from infected patients because they may be in close contact with the patient’s secretions (saliva, vomitus, blood, urine, stool, sweat) before the diagnosis is made and appropriate precautions are in place. Additionally, as patients become more ill, the amount of virus increases in the blood, further increasing the risk of transmission to those caring for the patient if proper precautions and personal protective equipment are not in use.
To my knowledge, we still do not have the sequencing of the recovered virus samples to determine which strain of Marburg virus this is and to determine whether this outbreak is the result of a single spillover event or multiple ones. Answering the question as to which strain this is is important because the mortality rates are different, the response to monoclonal antibodies are different, and the effectiveness of our current experimental vaccines appears to be different.
As of yesterday, the Republic of Rwanda Ministry of Health has reported that the outbreak has resulted in 46 confirmed cases with 12 deaths. Five people have recovered from the infection, while 29 people are still in isolation and being treated.
The U.S. has sent investigational vaccines (the Sabin chAd-3 vaccine which is in phase 2 trials) and monoclonal antibodies (MappBio’s MBP-091 mAb) (well, maybe we are learning the lessons from history!) to Rwanda on condition that the country conduct clinical trials to establish their safety and effectiveness. There are currently no licensed vaccines or therapeutics to prevent or treat this disease.
No cases have been identified in the U.S. or other countries outside of the continent of Africa, however, the WHO does note in its most recent situation update https://www.who.int/emergencies/disease-outbreak-news/item/2024-DON537 that due to the outbreak involving the capital of Rwanda that has an international airport, the potential for travelers to be infected while in Rwanda, but then manifest their disease in another country due to the long incubation period is a possibility. The CDC also sent out a health alert (https://emergency.cdc.gov/han/2024/han00517.asp) to U.S. physicians last Thursday. (I applaud the CDC for this. Many of us recall the case of Ebolavirus disease that appeared in a Dallas emergency room following travel from Africa that resulted in the infection of two nurses there, who fortunately survived their illness.
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