-- intro: The Ebola virus arrived in a fifth country this week, after health officials reported that a man with Ebola symptoms showed up at a hospital in Senegal. The man was a student from Guinea, where the virus has affected 648 and killed 430.
Across West Africa, the virus has already killed more than 1,552 people in Liberia, Guinea, Sierra Leone and Nigeria, according to the World Health Organization.
While doctors and government officials have spent months trying to stop the outbreak, the infections continue to rise: More than 40 percent of the total cases in this outbreak have occurred within the past 23 days.
Here are 10 things you should know about the outbreaks as fears continue to mount in Africa and beyond.
quicklist: 1 category: What's Happening Now in the Ebola Outbreak text: Senegal reported its first case of the Ebola virus this week after a student from Guinea sought treatment at a Dakar hospital.
An epidemiological surveillance team from Guinea alerted Senegalese officials they had lost track of a patient, who they suspected had traveled to Senegal, The Associated Press reported. Officials quickly realized the patient was being treated at hospital in the country's capital of Dakar.
Health Minister Awa Marie Coll Seck told reporters the patient was quarantined and that his condition was "satisfactory."
The country of more than 13 million is the fifth to be affected by the Ebola outbreak, which started in March. Earlier this month Senegal closed its border with Guinea and it is unclear how the infected patient managed to cross the border.
quicklist : 2 category: What's Happening Now in the Ebola Outbreak title: 'Unprecedented Number' of Health Workers Affected text: The World Health Organization reported that an "unprecedented number" of healthcare workers have been affected by the virus.
As of Aug. 25, the WHO reported, more than 240 health care workers have been infected by the disease. Of those infected more than 120 have died.
The death of hundreds of health workers has weakened an already fragile medical system in many of the countries affected. Top Ebola doctors in Sierra Leone and Liberia were killed earlier this year after treating patients.
Additionally five co-authors of a study about Ebola published in Science journal have died after working with patients. The co-authors were five out of 50 who worked to map the genetic code of the current Ebola outbreak.
Health workers are particularly at risk because they are in close contact with sick patients, who are at their most contagious. The virus is spread through close bodily contact and infected bodily fluids including blood, sweat and urine.
quicklist : 3
category: What's Happening Now in the Ebola Outbreak
title: Congo Reports Possible Ebola Cases, Deaths
text: The Democratic Republic of Congo may be 800 miles from the Ebola outbreak in West Africa, but the Central African country has reported 24 suspected cases, including 13 deaths. None of the patients or their close contacts had traveled to West Africa, according to WHO.
"At this time, it is believed that the outbreak in [the Democratic Republic of Congo] is unrelated to the ongoing outbreak in West Africa," the agency said in a statement today, adding that samples from the Congo cases are being tested for the virus.
The first known case in Congo occurred in a pregnant woman who became ill after butchering a "bush animal" that her husband killed, according to WHO. She died on Aug. 11. Health care workers who tended to her, including a doctor, two nurses and a ward boy developed similar symptoms and died, the agency said.
Ebola was first discovered in the Congo in 1976 and is named for the Ebola River.
quicklist: 4 category: What's Happening Now in the Ebola Outbreak title: WHO Worker With Ebola Evacuated to Germany text: Health workers infected with Ebola continue to be evacuated from West Africa and treated elsewhere.
The latest is a Senegalese WHO scientist who was evacuated from Sierra Leone for treatment at the University Medical Center Hamburg-Eppendorf, which has a renowned tropical disease center, according to the Associated Press.
Since the epidemiologist wasn't in the region to treat patients, but rather to coordinate with local health officials, WHO is trying to figure out how he got infected.
Other evacuees include the first British Ebola patient, a nurse stationed in Sierra Leone named Will Pooley, who was evacuated for treatment earlier this week, according to the AP. The Royal Air Force sent a special jet to collect Pooley and transport him to the Royal Free Hospital in London, the AP reported.
Pooley also reportedly received the experimental Ebola drug ZMapp.
quicklist: 5 category: What's Happening Now in the Ebola Outbreak title: African Patients Who Got ZMapp to Leave Hospital
text: There's no cure for Ebola, but at least six people have received the experimental drug ZMapp: American health workers Dr. Kent Brantly and Nancy Writebol, a Spanish priest, two African doctors, and one African nurse. Brantly and Writebol survived but the Spanish priest and one of the African doctors did not.
The remaining African ZMapp recipients were expected to be discharged from the hospital this week.
Still, experts say it's unclear whether ZMapp -- a cocktail of three antibodies that attack the virus -- actually helped those who received it. Before Brantly received his dose, the drug had only been tested in monkeys.
"Frankly we do not know if it helped them, made any difference, or even delayed their recovery," said Dr. Bruce Ribner, director of Emory University Hospital's infectious disease unit, where Brantly and Writebol were treated.
quicklist: 6 category: What's Happening Now in the Ebola Outbreak title: Health Teams Evacuate Sierra Leone
text: Canada has pulled a small team of scientists from Sierra Leone because unaffiliated people at the team's hotel were diagnosed with Ebola, according to the AP. The three-person team will stay in isolation for 21 days even though none of them has shown symptoms of the virus.
The World Health Organization also announced that it would pull workers from Kailahun, Sierra Leone, after a WHO employee unexpectedly contracted the disease. That employee, who did not treat patients, is receiving treatment in Germany.
More than 240 health care workers have contracted Ebola in the West African outbreak and more than 120 of them have died, according to WHO. At least five more health care workers are suspected to have died from Ebola in a separate outbreak in the Democratic Republic of Congo, the agency said today.
quicklist: 7 category: What's Happening Now in the Ebola Outbreak title: Officials Warn of 'Shadow Zones,' 'Invisible' Cases text: The Ebola outbreak is already the deadliest on record, and WHO officials say the impact may be far worse than reported.
The number of known infections -- currently 2,615 -- is underestimated because of those who hide the infected and bury the dead in secret, WHO said in a statement Aug. 22. The number also excludes so-called "shadow zones," which are rumored to have Ebola cases that go unconfirmed because of community resistance and a lack of medical staff, the agency said.
Health officials also suspect an "invisible caseload" in Liberia because new treatment facilities are filling with previously unidentified Ebola patients as soon as they open.
quicklist: 8 category: What's Happening Now in the Ebola Outbreak title: 1 in 4 Americans Fears Ebola Outbreak, Poll Shows text: About a quarter of Americans fear that they or someone in their family will come down with Ebola in the next year, according to a Harvard School of Public Health poll.
Harvard and SSRS, an independent research company, conducted the poll of 1,025 adults last week and found that 39 percent of respondents feared a large Ebola outbreak in the United States.
According to the poll, 68 percent of Americans thought the disease could spread "easily" and 33 percent said they thought there was an available treatment for it, both highlighting a lack of understanding about Ebola in this country.
In reality, the virus is only transmitted through contact with bodily fluids like blood and urine, and there is no cure. It's unclear whether ZMapp, the unofficial drug given to the American Ebola patients, helped or hindered their recovery, experts say.
quicklist: 9 category: What's Happening Now in the Ebola Outbreak title: Officials Request Exit Screenings at Airports, Seaports text: The World Health Organization has requested exit screenings at international airports, seaports and land crossings in all countries affected by the Ebola outbreak.
"Any person with an illness consistent with [Ebola virus disease] should not be allowed to travel unless the travel is part of an appropriate medical evacuation," WHO said in a statement. "There should be no international travel of Ebola contacts or cases, unless the travel is part of an appropriate medical evacuation."
Ebola symptoms include fever, weakness, muscle pain and sore throat, before they progress to vomiting, diarrhea and rash. Some people may also experience bleeding.
The WHO Ebola Emergency Committee advised against international travel or trade restrictions at this time.
quicklist: 10 category: What's Happening Now in the Ebola Outbreak title: Governments Are Reviving the 'Cordon Sanitaire' text: Officials from Guinea, Sierra Leone and Liberia have implemented a "cordon sanitaire" or sanitary barrier -- a cross-border isolation zone designed to contain people with the highest infection risk.
The tactic, used to prevent the spread of plague in medieval times, literally blocks off an area thought to contain 70 percent of the epidemic. But some experts say there's little proof that isolation zones can prevent the spread of disease.
"It may not be sufficiently structured so it can prevent people from leaving," said Dr. William Schaffner, an infectious disease expert at Vanderbilt Medical Center in Nashville, Tenn.
quicklist: 11 category: What's Happening Now in the Ebola Outbreak title: Fearful Communities Are Shunning Survivors text: An estimated 47 percent of people infected in the outbreak have survived the virus, according to WHO. But they face fear and shame from their communities.
Survivor Sulaiman Kemokai, from Sierra Leone, said people in his community are afraid to touch him even though he's been declared virus-free, the AP reported.
The Ebola virus can only be spread through contact with bodily secretions such as blood, urine or sweat. But misinformation is rampant in areas hardest hit by the virus, health officials said.
category: What's Happening Now in the Ebola Outbreak title: FDA Warns Against Fake Ebola Treatments text: The U.S. Food and Drug Administration is warning people to avoid fake Ebola treatments and vaccines being sold online. The agency said products claiming to protect people from the infection began popping up online after the outbreak began in March.
"There are currently no FDA-approved vaccines or drugs to prevent or treat Ebola," the agency said in a statement. "Although there are experimental Ebola vaccines and treatments under development, these investigational products are in the early stages of product development, have not yet been fully tested for safety or effectiveness, and the supply is very limited.
"There are no approved vaccines, drugs, or investigational products specifically for Ebola available for purchase on the Internet," the FDA added. "By law, dietary supplements cannot claim to prevent or cure disease."