Quitting smoking leads to an average weight gain of four to five kilograms (nine to 11 pounds) in the first year -- "significantly" more than previously thought, a study said Wednesday.

Most of the pounds are piled on in the first three months, a team of medical researchers wrote in the online journal bmj.com, as another group stressed that the health benefits of quitting far outweighed the risks of putting on weight.

Officials have slain 2.5 million birds at poultry farms in western Mexico over the past three weeks in an attempt to contain a bird flu outbreak, the agriculture ministry said Tuesday.

The virus responsible for Mexico's current bird flu outbreak, H7N3, has occasionally caused human disease in various parts of the world, according to the United Nations, but has not shown itself to be easily transmittable between humans.

Shaken awake by police on a park bench, a 12-year-old boy from Prague was so drunk he could neither walk nor talk -- grim evidence of an unparalleled alcohol scourge affecting underage Czechs.

The boy was one of seven whom police found falling-down drunk in the Czech capital on the last day of school in late June.

Laws that criminalize gay behavior create a host of legal tangles that waste resources and hinder an effective response to HIV/AIDS worldwide, an independent commission reported on Monday.

The report by the Global Commission on HIV and the Law also pointed to laws that make sex work a crime, laws that prevent interventions with injecting drug workers, and legislation that denies youths access to sex education.

American adults may boost their life expectancy by two years by sitting for fewer than three hours a day, researchers said Tuesday, while admitting this was a tough task.

Reducing television viewing to under two hours a day could similarly add 1.4 years, the U.S. team said in a paper in the online journal BMJ Open.

Contraceptive use saves the lives of more than a quarter of million women each year, either from death in childbirth or unsafe abortions, according to estimates published on Tuesday.

In 2008, 355,000 women died while giving birth or from illegal or dangerous abortions, a study published by The Lancet said.

Brazil said Monday it will breed huge numbers of genetically modified mosquitoes to help stop the spread of dengue fever, an illness that has already struck nearly 500,000 people this year nationwide.

Dengue affects between 50 and 100 million people in the tropics and subtropics each year, causing fever, muscle and joint ache as well as potentially fatal dengue hemorrhagic fever and dengue shock syndrome.

A deadly form of a common childhood illness has been linked to the mysterious child deaths in Cambodia that sparked alarm after a cause could not immediately be determined, health officials said Monday.

Lab tests have confirmed that a virulent strain of hand, foot and mouth disease known as EV-71 is to blame for some of the 59 cases reviewed since April, including 52 deaths, according to a joint statement from the World Health Organization and Cambodian Health Ministry. The numbers were lowered from the initial report of 62 cases.

Twelve factories in eastern China were closed down after children living nearby were found to have high levels of lead in their blood, state press reported Monday.

While local authorities sought to downplay the significance of the shutdown, it is the latest in a string of incidents to highlight the increasing environmental and health costs of rampant economic development across China.

A crippling heat wave that has held large swathes of the United States hostage gave way slightly on Sunday -- but not before leaving dozens dead in several states, officials and local media said.

After days of sweltering highs around 100 degrees Fahrenheit (38 Celsius) in the central and eastern parts of the country, forecasters said that cooler air was slowly swooping south from Canada.