There is very little data available on the extent of Zanzibar’s heroin problem, but even the most conservative estimates suggest heroin usage is devastatingly high.

Suleiman Mauly, a former addict who runs a network of rehabilitation centres across the islands says recent surveys show there are nearly 10,000 users among the islands’ population of one million people. That would mean one per cent of the islanders use heroin. Even that puts Zanzibar’s usage amongst the highest in the world, compared to rates in other countries recorded in the UN’s World Drug Report 2011. Some health experts estimate it is actually much higher – maybe even as high as seven per cent.

So why is Zanzibar – more commonly known abroad for its stunning beaches and historical architecture – affected by heroin so much?

Some of the older, former users I spoke to at Mauly’s Detroit Sober House rehabilitation centre said they remember the first time they ever came across the drug in Zanzibar, in the late 1980s - sailors from Europe would use heroin while their ships were docked at Zanzibar’s port, and curious Zanzibaris started to try it too.

In addition, although the port is small, it lies on shipping routes on which heroin is smuggled from producing countries in Asia to the big heroin markets in the US and Europe, so for many years there have apparently been large quantities of heroin passing through.

But fuelled by cheap prices, little drugs-education and few outreach programmes, addiction has since escalated and Zanzibar has become a substantial market in its own right. Mauly says nearly 10,000 users are each spending at least $6 per day, which means over $20m of heroin is sold in Zanzibar every year. Clearly, some people are making a lot of money from the islanders’ addictions.

Zachariah Mwiru, another former user at the Sober House we visited, says with heroin costing just $2 for a hit, getting started is very easy.  Once addicted, it is hard to hold down a job or earn an income, and so sustaining a habit becomes very difficult. He says he couldn’t hold on to a mobile phone or a pair of shoes for more than a couple of weeks before he sold it to buy drugs.

At the moment, only the lucky few have access to the rehabilitation centres – heroin users have to pay for their own upkeep, and for many addicts in Zanzibar it is simply unaffordable. Mauly says while he has managed to treat over 1,000 users, it is not possible to fully tackle Zanzibar’s heroin problem without free rehabilitation facilities available to all. He says the authorities are steadily waking up to the problem and allocating more resources, but with limited rehabilitation facilities and a cheap supply readily available on the streets, Zanzibar’s struggle against heroin addiction has a long way to go.

Former user Zachariah Mwiru talks about his struggle to get clean.