"When you have no money, this helps," a young Kenyan woman named Cecile said as she unwrapped tin foil with $2 worth of heroin and loaded it into a syringe. She put the needle into her friend Anna's jugular and slowly injected the drug. Anna slumped a bit as the heroin took effect. Then, using the same syringe, Cecile quickly withdrew some of Anna's blood and injected it into her own arm.

This method of reusing heroin, called "blood flashing," is a side effect of endemic drug addiction in Mombasa, Kenya's second largest city and East Africa's largest port. Over the past six years, the city has rapidly evolved into a major international heroin transit hub, with upwards of 40 tons of the narcotic flowing into Mombasa each year.

As regional conflict and enforcement have squeezed the traditional trafficking route through Central Asia and southeastern Europe, an alternative route — known by some as the Smack Track — has exploded in popularity, running south from Afghanistan across the Indian Ocean and through East Africa. After entering Kenya, the drug is trafficked throughout Africa and onward to Europe and American markets.

The Combined Maritime Force, a mission comprised of 30 navies patrolling the Indian Ocean to fight piracy and terrorism, has seized 1.7 tons of heroin so far this year after intercepting a record 3.4 tons in 2014.

"It seems very unlikely that the growing trade is going to do anything but increase blood flashing, which could have a significant impact," said Alan Cole, who heads the United Nations Office of Drugs and Crime's Transnational Organized Crime Program in eastern Africa. The transmission of HIV and viral hepatitis via this method, he noted, is a serious health concern.

Warning: This video contains graphic content.

Kenyan President Uhuru Kenyatta visited Mombasa in August and announced a crackdown on drugs that coincided with a major reshuffle of senior police. About two weeks earlier, the country's Interior Ministry blew up a yacht that had been seized in the Indian Ocean while smuggling heroin. The month before, Kenyan police found more than 341 kilograms of heroin in the diesel tank of a ship in the city's port — the biggest single seizure the city had ever seen.

"Those who bring in the drugs should know we shall destroy their ships and the drugs. We shall sink their ships into the ocean,'' Kenyatta remarked. "I know that you political leaders know the drug dealers. Therefore, you should volunteer the information to police so that they can be brought to book."

Local officials quickly fell into line, at least rhetorically, informing the public of an initiative that would root out dealers and drug lords while sweeping the city's addicts from the streets of poor neighborhoods like Majengo.

Two weeks into his new job, Mombasa Police Chief Francis Wanjohi said that smashing drug cartels is the campaign's primary aim. A police raid last week on a Norwegian transport ship moving cargo from India signaled the beginning of the effort, he added. The entire port was cordoned off and traffic in and out was halted for several hours. On Tuesday, authorities confirmed that weapons and drugs were found onboard, but did not offer details about the haul.

"It is slow and difficult because there are so many layers to the trade," Wanjohi said. "The small fish don't know where the drugs come from."

The UNODC estimates that more than 18,000 Kenyans regularly inject heroin, with almost half of them on Kenya's coast. Mwini Abbas, program coordinator for Reachout Center Trust, a drug rehabilitation organization that operates centers in and around Mombasa, said she is concerned that the government's crackdown was "victimizing the users and not pursuing the barons."

Those arrested are similar to Anna and Cecile, who five years ago started smoking joints laced with heroin and are now injecting every day. Users on the coast generally support themselves with sex work and petty crime. When Anna was asked how she and her friend make money, she answered, "We get screwed."

When Cecile, who gets needles from Reachout, said that she doesn't fear sharing blood with Anna because they "know each other," Anna nodded in agreement.

Kenya has one of the world's largest HIV epidemics. René Berger, who leads USAID's HIV program in the country, said that the threat of heroin use and practices like blood flashing to setback the progress that has been made in fighting the disease is significant enough for USAID to start a methadone program earlier this year.

"We know injection drug use is the most efficient way of transmitting HIV, so getting people off injection drug use via a methadone program is a great way to prevent transmission," he said. Berger added that high unemployment, sex work, and drug use in Mombasa were a potent mix behind the city's "sense of desperation."

Abbas said that police officers mistreat many of those who are arrested and rarely if ever provide them with healthcare while they await trial.

"Is rounding up these people really the solution?" he asked. "The demand is there, people are addicted. Arresting them is not going to fix this."

Abdulswamad Sheriff, a member of parliament who represents Mombasa's Mvita Constituency, blamed much of the city's drug problem on lax enforcement within the judiciary.

"Drugs are destroying our communities. The courts have to protect our citizens, and that's not happening," he said. He believes that harsher sentencing is needed.

"Despite rhetoric from Kenyan political leaders, there has been a lack of action in the form of high level prosecutions or interdiction," the US State Department's Bureau of International Narcotics and Law Enforcement Affairs said in a report released earlier this year. "Only a tiny fraction of the drugs believed to transit in and through Kenya are seized by authorities. Due to a lack of both political will and institutional capacity, arrests rarely lead to convictions. When convictions do occur in Kenya, they are of lower level couriers and distributors."

Sheriff conceded that public corruption and graft helps fuel the drug trade.

"But someone has to say who the big fish are," he remarked. "This is what everyone says: 'Get the big fish.' But we just do not know who is the big fish."

Cole, the UNODC official, said that traffickers and government officials are often paid in heroin, which they then sell to their local communities, creating a vicious cycle of dependency at both ends of the chain. In some spots along the coast, corruption is so lucrative that police officers are believed to sometimes pay their superiors to be reassigned there.

When asked about the role of law enforcement in abetting the drug trade, Wanjohi deflected the suggestion.

"Police are used to being blamed" for the problem, he said, adding that he was "not aware of any politicians" who are suspected of being involved. "You hear lots of rumors. We are closing in, we are making progress."