Here are some of the latest health and medical news developments, compiled by the editors of HealthDay:

6.6 Million Children Under Age 5 Died in 2012: UNICEF

Childhood death rates have fallen 50 percent worldwide since 1990, but about 6.6 million children under the age of 5 still died last year, according to UNICEF.

The U.N. children's agency said that five countries -- China, Congo, India, Nigeria and Pakistan -- account for nearly half of all the children who die, the Associated Press reported.

The leading causes of death are malaria, pneumonia and diarrhea, which claim the lives of about 6,000 children under age 5 each day. A lack of nutrition contributes to nearly half these deaths, UNICEF said.

"Progress can and must be made," said Anthony Lake, the agency's executive director, the AP reported. "When concerted action, sound strategies, adequate resources and strong political will are harnessed in support of child and maternal survival, dramatic reductions in child mortality aren't just feasible, they are morally imperative."

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Camels May Be Linked to Deadly Respiratory Virus in People

There is growing evidence that camels are the most likely bridge in the transmission of a lethal respiratory virus between bats and humans.

The virus that causes Middle East Respiratory Syndrome (MERS) has not been detected in camels, but antibodies that react to the virus have been found in the blood of camels in Sudan, Egypt, Oman and the Canary Islands, The New York Times reported.

The presence of the antibodies suggests that these camels have recovered from infection with the MERS virus or a closely-related virus.

Many of the 114 people known to have had MERS had no contact with camels, but the first confirmed or suspected cases in three separate clusters of patients may have had contact with the animals, and in two cases, the camels appeared to be ill, The Times reported.

One case involved a 38-year-old man in Saudi Arabia who was a camel dealer with at least one obviously sick camel. The man died of what was diagnosed as bacterial pneumonia, but other members of his family later became ill and were diagnosed with MERS, and two of them died, according to the Saudi newspaper Asharq.

In another case, a 73-year-old man in Abu Dhabi became ill shortly after contact with a sick racing camel in his stable. The first confirmed case of MERS was a man in Saudi Arabia who had four pet camels.

Surveillance for the MERS virus in the Middle East is inadequate, Henry Niman, a Pittsburgh biochemist who tracks viral mutations, told The Times. He said too few camels are being tested in countries with human cases of MERS, and people in poor countries who fall ill with what might be MERS are not being tested.