Two simultaneous outbreaks
of the Marburg virus, a close cousin of Ebola that can kill up to 90% of the people it infects, are raising critical questions about the behavior of this mysterious bat-borne pathogen
and
global efforts to prepare for potential pandemics.
Marburg hemorrhagic fever
is
rare: only a few outbreaks have been reported since the virus was identified in 1967.
A group of doctors in protective suits at a treatment center for Ebola patients in the Democratic Republic of the Congo.
(Diana Zeyneb Alhindawi/The New York Times)
But in recent years there has been a steady rise in cases in Africa, causing alarm.
Marburg causes
high fever, vomiting, diarrhea and, in the most severe cases, bleeding
from orifices.
It spreads from person to person through direct contact with the blood or other bodily fluids of infected people and with surfaces and materials such as clothing contaminated with these fluids.
One of the two outbreaks, in
Tanzania
(East Africa), appears to be under control, with only two people in quarantine.
But in the other, in
Equatorial Guinea
on the west coast, the spread of the virus continues, with the World Health Organization declaring last week that the country was not being transparent in reporting cases.
There are no treatments or vaccines
for Marburg, but there are some candidates that have shown promise in phase 1 clinical trials.
However, these candidates must be tested in animal clinical trials.
They need to be tested in active outbreaks to prove they work, and so far no vaccine supplies have been delivered to test in current outbreaks.
"The moment an outbreak is detected there should be a mechanism to act quickly," says Dr. John Amuasi, head of the department of global health at Ghana's Kwame Nkrumah University of Science and Technology, who investigated an outbreak of Marburg in that country last year.
shoots
The WHO and other agencies are good at rapid response to control the spread of a virus, but lack an equally rapid response for research.
They need
stocks ready
for shipment of candidate vaccines and researchers equipped to work without overburdening an already struggling health system.
The
WHO
claims to have drafted a research protocol that can be applied to these outbreaks and to any other filovirus - the family that includes Marburg and Ebola - and has been working against the clock to get the trials underway for more than a month.
If the outbreak response works well - isolating cases and tracing contacts - the epidemic will be quickly brought under control, as appears to be the case in Tanzania.
If the response does not go as well (as in Equatorial Guinea), there are fears of a
widespread outbreak
and a redoubled need for vaccination.
When an Ebola outbreak began in
Uganda
in September 2022, the strain that quickly claimed lives was one for which there was no vaccine, but, equally, there was a strong candidate waiting for a chance to be tested.
The researchers announced plans to test it in Uganda.
But the outbreak was already over when the vaccine doses arrived.
The outbreaks in Equatorial Guinea and Tanzania are the first recorded in both countries.
The Equatorial Guinea outbreak began in January.
The government has reported the deaths of nine people with confirmed Marburg virus disease and the deaths of
another 20 people
related to the confirmed cases who were not tested but are considered
probable cases.
The Equatorial Guinean government has provided little information about the outbreak, and the WHO has said that there are likely undetected chains of transmission and that not all known cases have a clear connection to each other, suggesting a greater spread than expected. what was thought
"The WHO is aware of additional cases, and we have asked the government to officially notify the WHO," said Dr. Tedros Adhanom Ghebreyesus, director of the agency, last week.
The Tanzanian outbreak was first reported in March.
Five people with confirmed Marburg infections have died there, including a health worker.
No new cases have been reported in Tanzania for two weeks, but the incubation period for Marburg is 21 days, so the outbreak is considered active.
"This is the hard part, with people in isolation, waiting for the days to pass," Kheri Issa, the Tanzania Red Cross's Marburg virus response officer, said in a telephone interview from the Kagera area where disease was declared.
According to the WHO, both outbreaks pose regional risks: Equatorial Guinea has porous borders with Cameroon and Gabon, and so far cases have appeared in geographically diffuse parts of the country.
In Tanzania, the Kagera region has heavily traveled borders with Uganda, Rwanda, and Burundi.
These outbreaks follow one in Ghana last year and Guinea the year before, marking a marked change from sporadic cases in previous years.
Amuasi said better monitoring is likely to have contributed to what appears to be an increase in cases.
As part of the response to the COVID-19 pandemic, he said, all African countries have improved their capacity for PCR testing and infectious disease surveillance, which means that Marburg is being diagnosed more frequently.
But this suggests that historically more of the virus may have circulated among humans than previously thought, according to Amuasi, and that the way it makes people sick may be different than previously thought.
Dr. Nancy Sullivan, director of the National Laboratories for Emerging Infectious Diseases at Boston University, believes that climate change, and the way it is changing human and animal behavior, is causing a real increase in cases.
"We are having a much greater impact on the reservoirs" of the virus, he said.
Sullivan designed the most advanced Marburg vaccine candidate in its development while working with the National Institute of Allergy and Infectious Diseases.
It demonstrated safety and immune response in a Phase 1 clinical trial, and the Sabin Vaccine Institute, a Washington-based nonprofit organization that promotes global vaccine development, continues the testing process.
The Sabin Institute declared that it had 600 doses of the vaccines in vials and ready for use, and expected an eventual reserve of 8,000 by the end of this year.
Sullivan said 600 doses would be enough to start a trial of ring vaccination of people at risk in
Tanzania and Equatorial Guinea.
But the WHO has yet to announce the operational details of a trial of this vaccine or three other vaccine candidates.
Transporting the doses to the country is only one of the challenges;
a trial would require a principal investigator from the country of the outbreak, legal agreements with the vaccine manufacturers, and regulatory approval.
Equatorial Guinea has a notoriously opaque government that has been under the control of President
Teodoro Obiang Nguema Mbasogo
and his family for more than 30 years.
Without committed resources and pre-approved testing protocols, filovirus outbreaks will continue to occur with little progress in interventions that could stop them, Amuasi said.
c.2023 The New York Times Company
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