In western Herat Province, held up as an island of stability and progress in Afghanistan, this forlorn border town is instead a showcase for an intensifying crisis: Long the global leader in opium production, Afghanistan has now also become one of the world’s most addicted societies.

The number of drug users in Afghanistan is estimated to be as high as 1.6 million, or about 5.3 percent of the population, among the highest rates in the world. Nationwide, one in 10 urban households has at least one drug user, according to a recent report from the Bureau of International Narcotics and Law Enforcement Affairs. In the city of Herat, it is one in five.

From 2005 to 2009, the use of opiates doubled, according to the United Nations Office on Drugs and Crime, putting Afghanistan on par with Russia and Iran, and the number of heroin users jumped more than 140 percent. Most drug experts think the rate of drug use has only increased since then.

In a country troubled by adversity, from its long-running war to rampant corruption, drug addiction ranks low among national priorities. Government funding for treatment and outreach is less than $4 million a year. There are just under 28,000 formal treatment slots available nationwide, officials say, and such programs rely heavily on roughly $12 million a year in extra international funding for treatment.