How is Ebola spread? What to know about causes, symptoms

An outbreak of a rare strain of Ebola in central Africa that has left at least 80 people dead has been declared a public health emergency of international concern by the World Health Organization.

WHO Director-General Tedros Adhanom Ghebreyesus, on May 17, announced the outbreak of the Bundibugyo virus, a species of Ebola, after at least 80 people were killed and nearly 250 suspected cases were reported in eastern Democratic Republic of Congo. The true number of suspected cases, meanwhile, are expected to be much higher, Reuters reported.

In neighboring Uganda, officials said laboratory results confirmed two cases in the capital of Kampala − including one death − among people traveling from Congo with no apparent link to each other. Another laboratory-confirmed case was also reported in Kinshasa, Congo's capital, infecting someone returning from the eastern Congolese province of Ituri where the outbreak is centered.

The WHO said the spread doesn't yet meet pandemic levels under international health regulations. Health experts told USA TODAY the risk to Americans is low at this time. The largest Ebola outbreak was previously recorded between 2013 and 2016, according to the Cleveland Clinic, which saw 28,652 cases worldwide, with 11,325 reported deaths in 10 countries.

The Centers for Disease Control and Prevention, in a May 17 news conference, said it has activated its emergency response center. The agency said it's also coordinating with interagency partners and providing in-country support for surveillance and contact tracing, among other prevention measures.

Here's what else to know about the infection.

What is Ebola?

Ebola is described as a "serious, life-threatening" type of viral infection that damages your blood vessels, according to the Cleveland Clinic. It is caused by a group of viruses, known as orthoebolaviruses, which can cause serious illness that can lead to death if not treated.

Orthoebolaviruses are found primarily in sub-Saharan Africa, according to the CDC.

How does Ebola spread?

Ebola virus is transmitted to people from wild animals, such as fruit bats, porcupines and non-human primates, with fruit bats believed to be the natural hosts of the orthoebolavirus. Humans can contract the virus through "close contact with the blood, secretions, organs or other bodily fluids of infected animals found ill or dead or in the rainforest," according to the WHO, though the CDC says it's rare.

Human-to-human spread occurs "through direct contact with the blood, secretions, organs or other bodily fluids of infected people, and with surfaces and materials (e.g. bedding, clothing) contaminated with these fluids," as per the WHO.

"People cannot transmit the disease before they have symptoms, and they remain infectious as long as their blood contains the virus," the WHO says.

Ebola symptoms

Ebola symptoms usually appear two to 21 days after contact with the virus, the CDC says, and often begin with "dry" and "generic" symptoms that may include fever, aches, pains and fatigue.

As the person becomes sicker, the illness typically progresses to "wet" symptoms such as diarrhea, vomiting, abdominal pain, rash and unexplained bleeding.

Other symptoms may include chest pain, shortness of breath, confusion, red eyes, skin rash, hiccups and seizures.

Ebola is tricky to clinically diagnose because symptoms at early stage of the disease are similar to other infectious diseases such as malaria, typhoid fever, shigellosis, meningitis and other viral haemorrhagic fevers.

Is there a vaccine for Ebola?

Yes. Ervebo has been approved by the U.S. Food and Drug Administration for the prevention of Ebola disease in the Orthoebolavirus zairense species only, the CDC says. The vaccine is recommended for adults 18 years and older who are at potential risk of exposure to the Ebola virus. However, it can only be administered to patients who meet specific criteria, the CDC said, adding those at risk are advised to contact their medical provider immediately for the best course of action.

The WHO, meanwhile, lists on its website two approved vaccines including Ervebo (Merck & Co.) and Zabdeno and Mvabea (Janssen Pharmaceutica), adding Ervebo vaccine is recommended as part of outbreak response.

Contributing: Eduardo Cuevas

Saman Shafiq is a trending news reporter for USA TODAY. Reach her at [email protected] and follow her on X and Instagram @saman_shafiq7.