The COVID-19 pandemic may now be over, for all intents and purposes, and the U.S. Centers for Disease Control and Prevention has now shifted its attention toward a new potential viral threat to the American people.

The CDC issued an alert last week for U.S. doctors and public health officials to be on the lookout for suspected cases of the Marburg virus, an Ebola-like disease that is rare but incredibly fatal, Axios reported.

That alert from the CDC followed two recent separate but distinct outbreaks of the viral hemorrhagic fever-inducing disease in two nations on opposite sides of central Africa, Equatorial Guinea to the West and Tanzania to the East.

BOLO issued for suspected Marburg virus cases

On April 6, the CDC issued an official Health Advisory through the Health Alert Network to advise doctors and public health officials about the Marburg virus disease outbreaks in the two African nations. Still, it stressed that thus far there had been no confirmed cases of MVD outside of those two nations or in the U.S.

There have been previous outbreaks of MVD in neighboring countries in that central region of Africa, however, and the animal known to commonly carry the disease, the Egyptian fruit bat, is prevalent in the area.

A person infected with the Marburg virus is highly contagious once they begin to display symptoms, which can include "fever, headache, muscle and joint pain, fatigue, loss of appetite, gastrointestinal symptoms, or unexplained bleeding," according to the CDC.

The virus is not airborne but rather is spread through contact with bodily fluids, including "urine, saliva, sweat, feces, vomit, breast milk, amniotic fluid, or semen," as well as contact with the bodies of dead patients, medical equipment, fabrics and materials, and hard or porous surfaces that may have been contaminated.

That CDC alert further noted that thus far there is no vaccine or treatment for MVD that has been approved by the Food and Drug Administration.

Outbreaks in Central Africa

The CDC Health Advisory highlighted how the Marburg virus outbreak in Equatorial Guinea is believed to have begun in late January with a cluster of suspicious deaths in a village but has since spread to five districts in four provinces of that nation by mid-March, with at least 14 confirmed cases of which 10 have proven fatal.

Separately, there was a late-March outbreak of MVD in Tanzania and, as of early April, there have been at least eight confirmed cases of which five have been fatal.

"Currently, the risk of MVD in the United States is low; however, clinicians should be aware of the potential for imported cases," the advisory stated. "It is important to systematically assess patients for the possibility of viral hemorrhagic fevers (including MVD or Ebola disease) through a triage and evaluation process, including a detailed travel history. Early identification of MVD or other viral hemorrhagic fevers is important for providing appropriate and prompt patient care and preventing the spread of infection."

Particular areas of concern for potential exposure to the deadly bat-borne pathogen, per the CDC, include "contact with a symptomatic person with suspected or confirmed MVD or an unknown illness; attending/participating in a funeral; visiting or working in a healthcare facility; having contact with bats or non-human primates; working or spending time in a mine/cave" within 21 days of the onset of symptoms.

High mortality rate

The Daily Mail reported that with regard to the Marburg virus outbreak in Equatorial Guinea, in addition to the 14 confirmed cases and 10 deaths from the disease, there were at least another 20 unconfirmed but probable cases that had all resulted in death.

It is unclear exactly how deadly MVD is and some estimates place the mortality rate for confirmed cases as high as 90 percent, though other estimates have pegged it closer to 50 percent. However, those estimates are for the more limited case-fatality ratio of confirmed cases and is likely higher for the unknowable infection-fatality ratio that includes all infected individuals.

A medical professional identified only as Professor Whitworth told the outlet, "Marburg outbreaks are always concerning because of the high case-fatality rate and the potential for spreading from person to person by close contact."

"This outbreak has occurred in a remote forested area of Equatorial Guinea which limits the potential for spreading fast or affecting many people," the professor continued. "It also appears to have been spotted quickly, the number of suspected cases is small and the first death under investigation occurred on January 7, so only about five weeks ago."

"The outbreak has occurred close to the international borders with Cameroun and Gabon so international coordination will be required," Whitworth added. "So, overall, the risk for Equatorial Guinea and the region is moderate, and the risk of it spreading outside the region is very low."