An outbreak of plague in Madagascar has killed two people, a health official said on Tuesday, marking the official start of the season when the disease is considered to be at its deadliest.Last year more than 200 people were killed before epidemics of bubonic and pneumonic plague were brought under control in November.The World Health Organisation (WHO) has warned that this year's strain could be even more virulent."According to counts undertaken between August 1 and September 13, we recorded eight suspected plague cases, six of whom recovered and two died in their villages," said health ministry official Manitra Rakotoarivony.The first fatality was recorded in Fiadanana, north of the capital Antananarivo, while the second was reported in Ambalavao in the Indian Ocean island's interior, added Rakotoarivony.Madagascar has suffered bubonic plague outbreaks almost every year since 1980, often caused by rats fleeing forest fires.The disease tends to make a comeback each hot rainy season, from September to April.On average, between 300 and 600 infections are recorded every year among a population approaching 25 million people, according to a UN estimate.Last year cases sprang up far earlier than usual and, instead of being confined to the countryside, the disease infiltrated towns. The authorities recorded more than 2 000 cases.The plague germ Yersinia pestis is typically transmitted to humans from infected rats via fleas. It can also be transmitted from human to human through cough droplets expelled by a person with a pneumonic form of the disease.Pneumonic plague can prove fatal between 24 to 72 hours while the bubonic form is less dangerous.* Sign up to News24's top Africa news in your inbox: SUBSCRIBE TO THE HELLO AFRICA NEWSLETTERFOLLOW News24 Africa on Twitter and Facebook.