LUANDA, Feb 3 (Reuters) - Rabies has killed over 50 children in Angola's capital Luanda in the past three months, raising alarm in a city with thousands of stray dogs whose infected bite can transmit the virus to humans, a health official said on Tuesday.

"This is something I have never seen in Angola before. The virus is extremely serious because it is like a death sentence to humans," said hospital director Luis Bernardino.

Rabies is an acute viral infection that is nearly always fatal when left untreated. It is usually transmitted through saliva in the bite of an infected animal, often a dog. Children are usually the biggest victims of rabies because they cannot protect themselves from dogs.

Authorities in Luanda have struggled to contain the virus. Last month a citywide vaccination campaign was carried out, in which 100,000 animals -- dogs, cats and monkeys -- were inoculated.

"In most cases children die from the virus because their families do not seek medical treatment on time," Bernardino said.

Angola, which is recovering from an almost three-decade-long civil war that ended in 2002, has one of the worst infant mortality rates in the world. Two in five children die before the age of five, according to the World Health Organisation.

Rabies kills about 50,000 people across the world each year. (Reporting by Henrique Almeida, editing by Mark Trevelyan)

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