Lying half-paralysed in a hospital bed in Doha and drifting in and out of consciousness, 33-year-old Dhana Prasad Gurung has become a physical manifestation of the Kafkaesque nightmare into which badly injured migrant workers can fall when the kafala system that ties them to their sponsoring companies breaks down.

Gurung left his wife and three young children in a remote village in western Nepal last June to work as a rubbish collector for a construction company in Doha, one of scores of subcontractors fuelling the £137bn building boom that underpins the country's "2030 Vision", of which the staging of the 2022 World Cup is an integral part.

Almost immediately, he began complaining of stomach problems but on each occasion was told to return to work without a medical examination.

According to a Nepalese organisation tracking his case, he was eventually told on 14 July that if he continued working for a little longer he would be allowed to return home to Nepal.

On 28 July, less than two months after he arrived in Qatar, co-workers found Gurung delirious and suffering from a very high temperature.

When he collapsed unconscious in his room, his co-workers eventually persuaded their supervisor to call a paramedic and he was taken to hospital. When he woke up the next day, he was paralysed.

"There were defects in the brain. The right and left side of the body were not working and he was fully paralysed," said a case-support officer for Pravasi Nepali Co-ordination Commission (PNCC), which helps the families of migrant workers killed and injured in Gulf states.

"We tried to get hold of the [kafala] owner but they were out of contact and are still out of contact. Because of that, they couldn't provide proper treatment at the beginning.

"The right hand side of his body is not working but there is a little bit of improvement in the left part."

While Gurung continued to be treated by the doctors at Hamad general hospital, who diagnosed him with "anoxic brain damage most probably secondary to heatstroke" and hypertension, the fact that his sponsoring firm could not be tracked down affected the standard of care he received.

Not only are the hospital fees unpaid but he has no passport, no official documents and no means to obtain the exit visa required to leave the country. Even if he was able to jump through those hoops and became well enough to return to Nepal, there is no one to pay his fare home.

Since human rights groups and the media alighted on Qatar as a highly visible example of the issues faced by migrant workers across the Gulf, the focus has largely been on the numbers killed.

But equally concerning for human rights organisations and campaigners are the difficulties faced by those seriously injured on the job who end up either trapped like Gurung, unable to afford treatment and unable to return home, or those who make it home but have such severe injuries that they are no longer able to provide for their families.

Under the kafala system, workers are tied to their employer and not allowed to change jobs or leave the country without their permission.

An Amnesty International report last November called on the Qatari authorities to compile and publish detailed data on workplace injuries and fatalities.The director of trauma and intensive care at Hamad hospital told Amnesty in February 2013 that injuries due to falling from heights at building sites had now reached more than 1,000 a year, with the mortality rate being "significant" and 10% of victims becoming disabled as a result.

Amnesty also found that migrant workers – both men and women – faced significant obstacles accessing healthcare if their employers had not issued them with residence permits. Without them, they must pay the high private fees charged to visitors for medical treatment.

A new law was passed last year to improve health insurance coverage, which is due to come into force for migrant workers in 2016.

But Amnesty's researchers found that several firms said they had not arranged residence permits for their workers due to cashflow problems and the cost of the process. The new system is expected to cost more and "may therefore have the effect of making access to non-emergency healthcare even more difficult for the affected groups".

The PNCC emphasises that it is not against Qatar hosting the World Cup or the employment opportunities offered by the huge development boom. But it insists these must be accompanied by vastly improved rights and conditions for migrant workers from Nepal and elsewhere.

"We are not against Qatar or holding the World Cup in Qatar: rather, we are against the rights violation of Nepali migrant workers in Qatar," said a spokesman.

According to PNCC's data, between 200 and 300 Nepalese migrant workers have been paralysed in Qatar and sent back to Nepal before receiving proper treatment.

Gurung has a six-month-old daughter he has never seen, who was born shortly after he left to work in Qatar. Ideally, his family would prefer him to stay in Qatar until his condition improves or doctors certify there is no possibility of improvement. But so concerned are they for his welfare, they would now settle for just having him home.

• The quote from the PNCC near the end of this story was added on 28 February 2014