The fatal gang rape of a 23-year-old woman on a moving bus in New Delhi in 2012 shook India’s collective conscience. The incident sparked a public debate about sexual violence and highlighted the need to improve the safety of women in the country. But as Indians took to the streets to call for better protections for women, there was one group of abuse victims that was all but ignored: the countless young women who are trafficked for sexual exploitation.

The latest data from India’s National Crime Records Bureau (NCRB) show that a total of 5,466 cases of human trafficking were reported under various sections of Indian law in 2014. The majority of victims were girls under the age of 18, and a small percentage were men. But the actual numbers are estimated to be much higher. The documentation of human trafficking in India is so inadequate, it is almost impossible to know the full extent of the crime, say experts.

“There is not a single set of data to rely upon,” says Bharti Ali, co-director of the HAQ Centre for Child Rights, a Delhi-based NGO. The data from the NCRB – which is aggregated by the government based on information available in police records – is sparse, while statistics released by the government under the Right to Information Act give a different set of numbers on human trafficking, she says.

The numbers may be hard to pin down, but according to a 2013 anti-human trafficking report by the United Nations Office on Drugs and Crime, trafficking for commercial sexual exploitation has been on the rise in India. And what is clear, says Ali, is that adolescents are highly vulnerable to trafficking.

Part of the problem is that these young people are hardly ever officially recognized as having been trafficked. Teenaged girls from economically weak and marginalized communities in rural India are often trafficked by people known to their families. Middlemen and even women sometimes convince parents to send their daughters to a city on the promise of better economic prospects, but soon after the girls leave their villages, they lose contact with their families.

The states of West Bengal, Andhra Pradesh, Karnataka, Maharashtra and Odisha have consistently been among the “high source areas” for purposes of trafficking to red-light areas across India, according to the U.N. report. And the data on missing girls in these states “continue to be very high,” the report says.

In certain parts of India, trading females for sex remains as a vestige of the ancient feudal culture. Men in these communities – which were labeled “criminal tribes” by the former British rulers of India – mostly don’t work, while women are forced into prostitution. “In some parts of Rajasthan [state], it is difficult to find girls between the ages of 15 and 25. They are sent off to dance bars in Mumbai or Dubai,” says Tinku Khanna, director of Apne Aap Women Worldwide, a charitable trust working with women affected by sex trafficking and prostitution.

When the police are approached to file a missing person’s report, in most cases, the information is entered in a “missing person’s diary,” according to the U.N. report. The cases are never registered as trafficking cases and sit as perpetually pending on the missing persons list.

Though human trafficking has been an offense for decades in India, it was only in 2013, after an amendment to the country’s criminal law, that an all-encompassing definition of trafficking was added to the books. Various stages involved in the process of trafficking, including the transporting and harboring of a victim, are now illegal, with the jail sentence ranging from a minimum seven years to life.

And a draft bill recently introduced by the government proposes to plug some of the existing holes in the legal system, including changing the provision that allows police to arrest both the trafficker and the victim. India has sufficient anti-trafficking laws in place – they just aren’t being implemented, says Mumbai-based women’s rights lawyer Anubha Rastogi.

The alleged nexus between the traffickers and corrupt police officers, administrators and politicians is another huge impediment to documenting human trafficking as well as punishing the guilty.

And traffickers know how to work the system, says Rastogi. They prep their victims on what to say if they get caught, threatening the girls with dire consequences if they tell the truth. When a young girl is rescued from a brothel, she can claim that she is a consenting adult. In the absence of any evidence suggesting otherwise, the presiding magistrate may be convinced and the girl could be let off with a fine of 500 rupees ($7.40) or sent to jail for up to six months for soliciting.

To tackle human trafficking, authorities and communities also need to address the social and psychological impact on women who are no longer considered profitable, experts say. There is a huge demand in the trade for younger girls. On turning 30, women are often literally thrown out into the street, says Khanna of Apne Aap Women Worldwide. Some of them get so desperate for money that they start working with their traffickers to lure other women into the business.

Addiction to alcohol or drugs is very common among these women, and many suffer from HIV, tuberculosis and malnutrition. “Many of them just die on the sidewalk,” says Khanna.

She advocates for a strong rescue and rehabilitation policy for trafficked victims. The existing support programs run by the government in partnership with NGOs, she says, do not look into counseling women who suffer from addiction and trauma, or help women sustain themselves.

Advocacy groups are concerned about the rescue shelters where many of these women end up, saying not enough money is being directed toward their upkeep. The groups also complain that there have been cuts in funding for welfare programs aimed at women and children.

Lalitha Kumaramangalam, chairperson of the National Commission for Women, an autonomous federal body, dismisses the claim that money has been snipped away from welfare programs.

She agrees with criticisms of the conditions of shelter homes. But, she says, the federal government cannot address the problem alone. While it can give money to the states, each state government has to independently prioritize how it wants to deal with the issue of human trafficking.

“There is also a need for the civil society to step in,” Kumaramangalam says. “The sheer burden of the population makes it difficult for the government to do everything by itself.”

An important step, she says, is that Indians need to start thinking of the women involved as victims who need to be protected, not shamed and discriminated against.