The World Health Organization, the U.N. health agency, declared in a statement that Nigeria and Senegal are free of the Ebola virus on Monday. While much of the news about Ebola has centered on Guinea, Liberia and Sierra Leone in West Africa, there have been several cases in Nigeria and Senegal.

On July 20, the virus was introduced in Nigeria when an infected Liberian man arrived by airplane into Lagos -- Nigeria's populous city. The man died in hospital five days later and set off a transmission that infected 19 others, seven of whom have died.

The end of an Ebola virus can be declared when 42 days have passed, and no new cases have been detected -- 42 days represents twice the maximum incubation period for the virus.

A U.N. worker has died from Ebola, according to a statement issued by U.N. Women. The man, Edmond Bangura-Sesay, was a driver for the U.N. agency in Sierra Leone, and he died Saturday. He had worked with the agency for five years. He was quarantined last Tuesday after his wife showed symptoms. His wife remains under treatment.

A thousand people are being watched for symptoms of Ebola, reported The Los Angeles Times. Either people are monitoring themselves or checking with a counselor at the Centers for Disease Control and Prevention (CDC).

Included in the 1,000 person watch list is a large pool of passengers who flew on a Frontier Airline plane used by the nurse Amber Vinson who is being treated at Emory University Hospital in Atlanta. An estimated 880 people flew on the craft that flew at least five flights after Vinson's. CDC and the airline are interested in talking to 132 passengers that flew with Vinson, on Flight 1143 from Ohio to Dallas on Oct.13.

Texas health officials say 43 people on the Ebola watch list have passed the 21-day maximum incubation period for the virus and are now in the clear, according to The Associated Press. Others who cared for the Liberian man, Thomas Eric Duncan, who died at Texas Health Presbyterian Hospital in Dallas on Oct. 8, remain at risk along with two nurses he infected and their close contacts. About 120 people will be monitored until Nov. 7.

The U.S. is looking to boost production of the experimental Ebola treatment. The U.S. Department of Health and Human Services through its BARDA division, issued an order on Thursday for mass producing the antiviral cocktail. Three advanced biological laboratories have until Nov. 10 to submit plans with budgets and timetables, according to Reuters.

Efforts to boost ZMapp production capacity are underway under the umbrella organization the Centers for Innovation in Advanced Development and Manufacturing composed of three separate labs -- Texas A&M Health Science Center in partnership with Britain's GlaxoSmithKline PLC, Emergent Biosolutions in Maryland and Novartis AG lab in North Carolina.

"We look forward to leveraging our manufacturing capabilities to expand production of this experimental therapeutic and to find other ways to support the U.S. government's fight against Ebola," said Adam Havey, president of Emergent Biosolutions biodefense division.

Havey told Reuters the company has been in discussions with plant manufacturers to develop a response to order for mass production.

The three labs were given seed money by the U.S. government in 2012 of $440 million to develop flexible manufacturing capabilities to produce vaccines and drugs against chemical, biological and other threats. This will be the labs first order for production.

Supplies of ZMapp, originally manufactured by San Diego-based Mapp Pharmaceuticals, ran out in August after they were used to treat two American medical workers who contracted the disease in Liberia -- Dr. Kent Brantly and Nancy Writebol. Both of the workers recovered. The drug is a cocktail of antibodies engineered to recognize the virus and bind to infected cells and is made from genetically modified tobacco plants.