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Five people in Germany have Zika virus infections, having visited Latin America and the Caribbean in recent months, German health officials say.

Zika is thought to cause a form of infant brain damage, microcephaly.

Brazil is the country worst affected by the Zika outbreak, with 270 cases of microcephaly confirmed by the health ministry and 3,448 being investigated.

German virologists say the type of mosquito that carries Zika - Aedes aegypti - does not exist in Germany.

The mosquito is known to be spreading through Latin America and the Caribbean.

The German health ministry said a patient in Bavaria "spent some time on the island of Martinique in early January, but has got better since then".

Three to four million people could be infected with Zika in the Americas this year, experts have warned.

Some experts are concerned that another mosquito - Aedes albopictus - might spread Zika, and that species does inhabit parts of southern Europe.

Concerns have arisen about Brazil's ability to safely host this year's Olympic Games in Rio de Janeiro. Thomas Bach, the head of the International Olympic Committee, has said steps are being taken to protect the event.

The IOC said it would issue guidelines later on Friday for athletes and visitors taking part.

Abortion petition

A group of Brazilian lawyers, activists and scientists is to ask the country's supreme court to allow abortions for women who have contracted the virus.

Abortions are illegal in Brazil, except in health emergencies or cases of rape or, since 2012, another brain condition known as anencephaly.

The new petition is to be delivered to the supreme court in two months' time. The BBC has learned that it argues that "the Brazilian state is responsible for the Zika outbreak" for not having eradicated the Aedes aegypti mosquito.

Most people do not develop Zika symptoms but may pass the virus on to their children. There is no known cure or vaccine. The US says it hopes to begin human vaccine trials by the end of 2016.

The head of the World Health Organization (WHO), Dr Margaret Chan, said Zika had gone "from a mild threat to one of alarming proportions". She has set up a Zika "emergency team" following the "explosive" spread of the virus.

The team will meet on Monday to decide whether Zika should be treated as a global emergency.

Zika was first detected in Uganda in 1947, but has never caused an outbreak on this scale. Brazil reported the first cases of Zika in South America in May 2015.

WHO officials said between 500,000 and 1.5 million people had been infected in Brazil, and the virus has since spread to more than 20 countries in the region.

What is the Zika virus?

• Spread by the Aedes aegypti mosquito, which also carries dengue fever and yellow fever
• First discovered in Africa in the 1940s but is now spreading in Latin America
• Scientists say there is growing evidence of a link to microcephaly, that leads to babies being born with small heads
• Can lead to fever and a rash but most people show no symptoms, and there is no known cure
• Only way to fight Zika is to clear stagnant water where mosquitoes breed, and protect against mosquito bites