Fatma Shaibu keeps regular hours. During the day she does housework in Stone Town, capital of the Indian Ocean island of Zanzibar, and at night she sells sex to customers at the local disco. Her escape from the daily grind is three heroin injections - morning, afternoon and night. In-between the mother of four stays high by smoking drugs with a foil and pipe.

"I'm sick and tired," Shaibu, 40, told IRIN/PlusNews, lifting her Muslim headscarf to expose purple neck veins bulging from years of shooting heroin into them; the blood vessels in her arms and legs collapsed long ago.

"It's not easy to find the money every day," she said. "I do everything because I need to smoke."

Shaibu is a textbook case of how HIV is spread in Zanzibar. Beyond the island's palm-fringed coast and exotic beaches loom the problems of drug addiction and prostitution, which do not bode well for the fight against HIV/AIDS.

For now, HIV prevalence is at less than one percent among the island's one million, mainly Muslim, population; much lower than in mainland Tanzania, about 50km away, where the caseload is seven percent in a population of 38 million.

However, Zanzibar's health authorities warn that the HIV infection rate among drug injectors and sex workers is much higher than in the general population.

A 2006 study of 508 injecting drug users found that 26 percent were HIV-positive, with another 22 percent suffering from hepatitis C, and 15 percent from syphilis.

The study also found that addicts were more likely to make their sexual debut as teens; to have multiple, concurrent sexual partners; and to engage in unprotected sex, further increasing their risk of contracting HIV.

"This is not one of those studies that can be shelved, the burden is just too much," said Dr Mohammed Dahoma, who led the survey and works at Stone Town's main medical facility, Mnazi Moja hospital. "It is a threat: [injecting drug use] is one of the key drivers of the AIDS epidemic, and particularly affects young people."

Drugs and AIDS

Concern is mounting that Zanzibar's AIDS burden could swell as drugs become more widely available: local police report that three percent of the adult population use illegal drugs, and the number is growing.

Zanzibar lies on a drug-trafficking route between Asia, the Middle East and Europe, which has contributed to greater use of heroin in the region, according to the Zanzibar AIDS Commission.

In 2005, police intercepted 375 metric tonnes of cannabis, 101.5kg of heroin and 35kg of morphine, among other prohibited substances. Over the past two years, 11,500 people have been arrested on drug-related charges, according to Tanzania's anti-narcotics unit.

Many injecting drug users share dirty needles or use a dangerous cash-saving technique known as "flash blood", in which a user injects heroin or another illicit substance and then draws a syringe full of blood that is passed to a second user to inject.

Poverty is part of the problem in Zanzibar, where the average per capita income is US$330. The 2006 study found that users often turned to prostitution to support a drug habit costing up to $8 a day.

Some observers also complain that tourism, one of Zanzibar's top foreign exchange earners, is contributing to an "un-Islamic" Western lifestyle. "There are aspects of life changing here, with more tourists coming and a faster place of life than the past," said Sadaat Idi of the Zanzibar AIDS Commission.

Mussa Ali, a project officer at ZAYADESA, a HIV-clinic in Stone Town, said its 500 HIV-positive members tried their best to support one another. "We don't ask one another how we got the disease; we just try to help ease the burdens it brings."

Hard to stop

Shaibu has tried to quit drugs and on both occasions ended up in the Zanzibar mental hospital, but left early because she said it was too hard being around patients with serious psychological problems. She blamed the absence of a dedicated drug treatment facility and inadequate support services on her inability to kick the habit for good.

Dr Dahoma said efforts to reach drug users should include improved treatment and care, as well as early-age school programmes to discourage drug abuse in the first place.

The government recently launched a US$3 million, two-year programme to combat AIDS in Zanzibar that includes strategies to crack down on drug smuggling and improve healthcare services for illicit substance users.

Health advocates have welcomed the government's effort. "We don't have the resources to fight this if it blows up - it is encouraging that the government is investing now," Dr Dahoma said.

In July, Tanzania also kicked off a high-profile campaign to screen four million people for HIV by the end of 2007, with free antiretroviral treatment to everyone needing it. President Jakaya Kikwete was tested in public to help break down the stigma and discrimination attached to HIV and AIDS.

But Shaibu, who does not know her HIV status, said it would take a lot more to change her chaotic lifestyle. "Here, the government doesn't understand the problem of heroin - people just tell me to stop. I can't do it on my own. I need a place where I can go and where it's peaceful, with no temptations."