Ebola Transmission Has Stopped in West Africa for the First Time in Two Years

For the first time since December 2013, transmission of the Ebola virus in West Africa is said to have stopped, according to the World Health Organization. It made the announcement as it declared today that Liberia's outbreak has officially ended — the third time it has done so since the largest Ebola outbreak in history began its spread.

"WHO declares the end of the most recent outbreak of Ebola virus disease in Liberia and says all known chains of transmission have been stopped in West Africa," the United Nations health agency said in a news release. "But the Organization says the job is not over, more flare-ups are expected and that strong surveillance and response systems will be critical in the months to come."

Thursday marks 42 days since the last Ebola patient in the country tested negative for the virus, completing the length of time required by WHO to declare an end to transmission. After previous declarations on two separate occasions in 2014, in November Liberia saw another flare-up of the deadly hemorrhagic fever that has claimed 11,300 lives across Guinea, Sierra Leone, and Liberia over the last two years.

"WHO commends Liberia's government and people on their effective response to this recent re-emergence of Ebola," said Dr. Alex Gasasira, the WHO representative in Liberia. "The rapid cessation of the flare-up is a concrete demonstration of the government's strengthened capacity to manage disease outbreaks. WHO will continue to support Liberia in its effort to prevent, detect, and respond to suspected cases."

Ebola first showed up in Liberia in the spring of 2014 after crossing the border from Guinea, where the virus initially took hold in the forest region of the West African country in December 2013. Ebola quickly made its way to Monrovia, the nation's capital — a rare instance of the virus hitting an urban area in the nearly 40 years since it was discovered in the forests of central Africa.

Poor healthcare infrastructure, lack of preparedness, a slow international response, and community disbelief all combined to perpetuate West Africa's first-ever outbreak of Ebola, which causes symptoms that include fever, vomiting, diarrhea, and even hemorrhaging during the late stages.

As the outbreak spiraled out of control in Guinea, Sierra Leone, and Liberia in the summer of 2014, the chaos in Liberia peaked in August and September of that year. As news outlets broadcast footage around the world of people lying sick in the streets of Monrovia as they awaited medical attention, the international community kicked into gear and the WHO declared a public health emergency of international concern. Countries sent funds and manpower to aid in the response efforts, with the US dispatching its military to Liberia to build temporary hospitals and clinics.

Marking the end of Ebola transmission on Thursday, the international medical charity Médecins Sans Frontières, also known as Doctors Without Borders (MSF), called on the international community to draw from these lessons to improve future response efforts.

"We must all learn from this experience to improve how we respond to future epidemics and to neglected diseases," said Joanne Liu, MSF's international president. "This Ebola response was not limited by lack of international means but by a lack of political will to rapidly deploy assistance to help communities. The needs of patients and affected communities must remain at the heart of any response and outweigh political interests."

Over the course of the 25-month-long outbreak in West Africa, MSF treated more than 5,000 patients who tested positive for Ebola, plus thousands of others with Ebola-like symptoms. Nearly 29,000 people contracted the virus in Guinea, Sierra Leone, and Liberia in total, along with cases that showed up in Nigeria, Senegal, Mali, Spain, and the United States after visitors or healthcare workers arrived in those countries while infected.

Moving forward, WHO said it is working to ensure robust prevention, surveillance, and response capacity as the countries enter a critical test to ending the Ebola outbreak for good. As has been the case in Liberia, the organization expects occasional flare-ups in the effected countries, likely a result of the fact that the virus is believed to stay in the system of survivors for up to nine months — a sharp increase over previous estimates of 90 days. For the time being, all three countries will remain under heightened surveillance for a 90-day period, which will end in February 2016 for Sierra Leone and March 2016 for Guinea and Liberia.

Since March, WHO said that transmission through survivors is believed to have sparked 10 new chains of minor Ebola outbreaks, known as flares, in addition to the original outbreak. With more than 10,000 survivors across the three countries, WHO's special representative for the Ebola response, Bruce Aylward, has stressed the importance of continued vigilance in the region as the persistence of the virus in this population could give rise to new Ebola flares into 2016.

"We are now at a critical period in the Ebola epidemic as we move from managing cases and patients to managing the residual risk of new infections," Aylward said in a statement on Thursday. "The risk of re-introduction of infection is diminishing as the virus gradually clears from the survivor population, but we still anticipate more flare-ups and must be prepared for them."

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