Since the outbreak began in August, 165 people have died and more than 2,000 have become infected with plague as of Wednesday.
Of those infections, 77% were clinically diagnosed as pneumonic -- or pulmonary -- plague, a form of the infection that can spread from person to person.
Plague is caused by the bacterium Yersinia pestis and is typically spread through the bite of infected fleas, which are frequently carried by rats, causing bubonic plague.
Pneumonic plague is more virulent or damaging and is an advanced form characterized by a severe lung infection. The infection can be transmitted via airborne droplets from coughs and sneezes.
After a sharp rise in cases in the initial weeks of the outbreak, the number of new cases began to decline in mid-October, according to the World Health Organization.
"After a concerted efforts by the Ministry of Health and partners, we are now seeing a decline in reported plague cases, in the number of people hospitalized with plague and in geographic districts reporting new cases," WHO spokesman Tarik Jasarevic said.
Between October 30 and November 3, there were 41 new cases and three deaths -- a significant decline from 238 cases and 12 deaths the week before.
"This trend is encouraging and shows that the quick steps taken to support the Malagasy government to contain the outbreak have been effective," Jasarevic said.
However, nine neighboring countries and territories remain on alert and have been identified by the WHO as priority countries in the African region in terms of ensuring preparedness against the plague.
These countries are Comoros, Ethiopia, Kenya, Mauritius, Mozambique, Réunion island, Seychelles, South Africa and Tanzania, given they have trade and travel links with Madagascar.
Preparedness involves increased public awareness, enhanced surveillance for the disease -- particularly at ports of entry -- stocks of drugs and equipment.
"It is normal that neighboring countries and those with direct trade and travel links to review plague preparedness measures given the outbreak in Madagascar," Jasarevic said.
Plague outbreaks are typical in Madagascar, with an estimated 400 cases each year.
The unusual spread of pneumonic plague in this outbreak was due to one infected person who traveled to find care early in the outbreak, infecting people along the way. Its arrival in cities, along with the outbreak beginning three months earlier than usual, further aided the spread of infection.
"The risk to people in UK is very low, but the risk for international travelers to and those working in Madagascar is higher," said Dilys Morgan, head of emerging infections and zoonoses at Public Health England.
The overall global risk is considered low, according to the WHO, and the regional risk is moderate.
"It is important that travelers to Madagascar seek advice before traveling and are aware of the measures they can take to reduce the risk of infection," Morgan said. "Plague is no longer the threat to humans that it was centuries ago, as antibiotics work well if treatment is started early."
This outbreak has garnered an international response from multiple nongovernmental organizations and health bodies including the the UK Public Health Rapid Support Team, the WHO, the US Centers for Disease Control and Prevention, Medecins Sans Frontieres (Doctors without Borders), the Institute Pasteur and the International Federation of the Red cross.
Travel and trade restrictions have not been advised.