A total of 805 cases have been reported on the poor Indian Ocean island nation since August, the health ministry said in a statement.
Madagascar has suffered plague outbreaks almost every year since 1980 — typically between September and April — and are often sparked by rats fleeing forest fires.
The current outbreak is unusual as it has affected urban areas — especially the capital Antananarivo — increasing the risk of transmission, according to the World Health Organisation.
It has sparked panic despite the government appealing for calm.
Passengers at Antananarivo’s transport hubs are subject to medical inspections, infected areas have been fumigated to kill fleas, public gatherings are banned, and schools and universities have been shut to combat the outbreak.
WHO has delivered 1.2 million doses of antibiotics vital to fighting the disease while the Red Cross has been urgently training hundreds of volunteers on the island to publicise preventative measures.
Plague bacteria develops in rats and is carried by fleas.
In humans, the pneumonic version is transferred through coughing and can be fatal within 72 hours.
Most of the victims recorded in Madagascar have been infected with the pneumonic form. The bubonic form is less dangerous.