Researchers have found a new mosquito in the west African nation of Burkina Faso that appears to be highly susceptible to malaria parasites and could help the disease spread, said a study Thursday.

The new subtype of Anopheles gambiae mosquitoes is believed to live mainly in the wild, whereas other species collected by scientists have been plucked from indoors where they are easier to find.

Nearly 3 million lives have been saved by HIV/AIDS treatment but scare resources are being misspent and stigma is still keeping the most vulnerable from seeking help, according to a new book by researchers commissioned by the U.N.

The failings are particularly worrying at a time when worldwide recession and donor fatigue are hurting spending on AIDS, the researchers say.

The cancer drug Avastin, also known as bevacizumab, is linked to a higher risk of death when combined with chemotherapy, said a study Tuesday in the Journal of the American Medical Association.

The drug has previously been found to raise the risk of blood clots in the legs and lungs by 33 percent, and in December the U.S. Food and Drug Administration said it was neither safe nor effective against breast cancer.

The U.S. government on Monday released new dietary guidelines urging all Americans to cut their daily salt intake by one-third and those over 50 to make more drastic reductions.

'"The 2010 Dietary Guidelines are being released at a time when the majority of adults and one in three children is overweight or obese," Agriculture Secretary Tom Vilsack said in a statement.

Children injected with the Pandemrix swine flu vaccine were nine times more likely to contract narcolepsy than those who were not vaccinated, a preliminary study by Finland's National Institute for Health and Welfare, THL, showed Tuesday.

"Currently, the most likely explanation is that the increase in narcolepsy is by joint effect of the vaccine and some other factor(s)," THL said.

A section of the brain involved in memory grew in size in older people who regularly took brisk walks for a year, researchers reported Monday.

The new study reinforces previous findings that aerobic exercise seems to reduce brain atrophy in early-stage Alzheimer's patients, and that walking leads to slight improvement on mental tests among older people with memory problems.

U.S. researchers have found a way to predict how successful a smoker will be at quitting by using an MRI scan to look for activity in a region of the brain associated with behavior change.

The scans were performed on 28 heavy smokers who had joined an anti-smoking program, according to the study published Monday in the peer-reviewed journal Health Psychology.

Moscow and at least two other cities shut all their elementary schools Saturday to help fight one of the worst flu outbreaks to hit central Russia in more than a decade, officials said.

The Moscow closure would affect more than 1,500 schools.

Venezuelan health authorities appealed Thursday to more than 400 people exposed to cholera at a wedding in the Dominican Republic to report for treatment in order to head off an epidemic.

So far, 37 people have been treated for cholera in Venezuela but authorities were still trying to locate the rest of the 452 people who traveled to the Dominican Republic for the January 22 wedding.

Eating foods high in trans-fats and saturated fats increases the risk of depression, according to a Spanish study published in the U.S. Wednesday, confirming previous studies that linked "junk food" with the disease.

Researchers also showed that some products, such as olive oil, which is high in healthy omega-9 fatty acids, can fight against the risk of mental illness.