Different strains of the human immunodeficiency virus (HIV) are now becoming more resistant to one of the more commonly used drugs for the prevention and treatment of the condition, a new study finds.

The study was conducted by researchers from the University College London, led by Dr. Ravi Gupta. The findings were published in The Lancet Infectious Diseases on Jan. 28.

According to the study, commonly used HIV drug, Tenofovir, is losing its effectiveness in treating the condition. To arrive at their conclusion, researchers studied about 2,000 patients worldwide who are positive with the virus. These patients were given the drug between 1998 and 2015.

Gupta explained to BBC News that if the right levels of Tenofovir are not taken or if the right dose is not maintained, the virus easily becomes protected from the effects of the drug. "Tenofovir is a critical part of our armamentarium against HIV, so it is extremely concerning to see such a high level of resistance to this drug," the lead author added.

In Africa, around 60 percent of patients have developed resistance to Tenofovir, while 20 percent were found in Europe. Gupta highlighted that the problem of drug resistance is particular in the African regions, where cases of failed therapy often go unnoticed.

Proper monitoring of HIV treatment is necessary to find out if the therapy failed or succeeded. With undetected failed therapy, the virus will have enough time to mutate into drug-resistant strains, Gupta said, according to ABC.

Meanwhile, the study also found that viruses resistant to Tenofovir may be passed on to other people. Gupta said that people should not be complacent as it's possible for the resistant strains to spread. 

"We are now conducting further studies to get a more detailed picture of how Tenofovir-resistant viruses develop and spread," Gupta told BBC.

With these new findings, the pressure is on to develop newer treatments before the existing drugs become a helpless case. If Tenofovir-resistant HIV becomes an uncontrolled case, people will soon resort to more expensive alternatives that also have more unpleasant side effects.