But as the strain of her husband being jailed for stealing a cow and leaving her penniless, with an 18-month-old baby and hostile in-laws, took its toll, on an island where a hit of heroin is cheaper than alcohol, Arafa’s sorrows quickly turned to ruin. “The beer was 2000 shillings ($1) and the heroin 1000 ($0.50)”, Arafa recalls of the first time she smoked the drug at one of many secret bars near Zanzibar city.

Its UNESCO-protected Stonetown – a maze of curio shops and Swahili ruins nestled into narrow alleyways – and sparkling beaches attracts boatloads of tourists each year. But the island is also attracting boatloads of heroin that the United Nation’s Office on Drugs and Crime says is increasingly putting East Africa on the global “smack track” via a southern route from Iran, Pakistan and Afghanistan on to Europe.

“In 2014, more than 2,200kg of heroin were seized on the Indian Ocean by the Combined Maritime Forces (CMF), which is more than the total reported heroin seizures for the whole of Africa between 2011 and 2013?, the UNODC said in its 2015 World Drugs Report. The 30-nation backed CMF has netted a record 1.7 tons of heroin in east African waters since May. But the drug is still flooding Zanzibar, where, at $15 a gram, seven percent of the 1.3 million islanders are hooked.

“The first time I tried it, it almost killed me, but I kept using it and some of the highs gave me such a good feeling I kept going”, says Arafa, who ended up selling her body for $2.50 a time to fund her habit. She is now recovering in Zanzibar’s only sober house for women, using a 12-step programme set up by Recovery Community Zanzibar.

The government in Zanzibar and Tanzania has also set up methadone programmes to try to wean people off a drug that is increasingly washing up on their shores. Just across the waters from Zanzibar, on the coast of mainland Tanzania, lies the former port town of Bagamoyo. Here, men loading charcoal and other mainland goods on boats bound for the island say that they come back at night loaded with other cargo.

“It just comes and happens in secret so you don’t see it”, says Hohammed Haji, adding that Bagamoyo has more than its fair share of drug addicts. Godfrey Nzowa, who runs Tanzania’s anti-narcotics unit, lists a 2011 bust in Bagamoyo of 180kg of heroin as one of many examples of how hard it is to police a 1,000-mile-long coastline full of poor villages where small packages can be easily smuggled to shore.

“They use motherships to smuggle heroin from the source country, and then after reaching a certain point at the high seas is when the receivers can use the speedboats to receive the consignment”, he says. Although keen to list his attendance at conferences in neighbouring countries, Nzowa is vague on details about how his office and its Zanzibar counterpart work together.

Recovery Community Zanzibar manager Kassim Nyuni’s work brings him into contact with the island force meant to be fighting men Nzowa calls “very lethal, very sophisticated, very patient and very disciplined” with very little.

“They haven’t got cars, they haven’t got computers in offices or enough educated police – they’re not serious”, he says. And it’s not just money and manpower crippling their efforts. “They don’t have access to do the job, and this business is being done by big, big people, rich people, people in government, so you cannot just stop it like that”, he adds, clicking his fingers. Nzowa has headed the Tanzania unit for a decade, refuses to retire, and is known for appearing incorruptible and at the top of every drug lord’s hit list.

But his protection seems to consist of a Bible he pulls out of the filing cabinet in an office cramped by boxes of seized drugs, and two bodyguards called “John and Mrs John” that turn out to be cats. The feline couple may be feared in Tanzania, where cats are thought to be witches, but they seem only to wrap themselves around Nzowa’s legs and purr noisily.

Nzowa is guarded about Tanzania’s role in stopping the drugs from arriving, defensive about the role played by foreign navies but reliant on onshore tip-offs from foreign and domestic sources. “You have to have informants. You know information is power always”, he says.

One unlikely informant turned out to be John Wotherspoon, a Catholic priest living in Hong Kong, who noticed the increasing amount of Tanzanian men jailed in Hong Kong for smuggling.

He started publishing their letters, that included the names of Tanzania’s high profile and alleged drug barons before inmates claimed an ambassador came to silence them with threats against their families. One recovering addict in the Zanzibar sober house fears a spike in drug shipments before October’s parliamentary and presidential elections. Her husband used to make up to $500 dealing heroin, and clocked the rise in arrival before the 2011 vote.

“Right now drugs is increasing, and I’m even afraid for my own brother and kids”, she says.

* The International Women’s Media Fund (IWMF) supported Hannah McNeish’s reporting from Tanzania as part of its African Great Lakes Reporting Initiative.