An aggressive new strain of HIV has been detected in Cuba. Photo by Steve Collender/Shutterstock

HAVANA, Feb. 14 (UPI) -- A new HIV strain in some patients in Cuba appears to be much more aggressive and can develop into AIDS within three years of infection. Researchers said the progression happens so fast that treatment with antiretroviral drugs may come too late.

Without treatment, HIV infection usually takes 5 to 10 years to turn into AIDS, according to Anne-Mieke Vandamme, a medical professor at Belgium's University of Leuven. According to the study, published in the journal EBioMedicine, Vandamme was alerted to the new aggressive strain of HIV by Cuban health officials who wanted to find out what was happening.


"So this group of patients that progressed very fast, they were all recently infected," Vandamme explained to Voice of America. "And we know that because they had been HIV-negative tested one or a maximum two years before."

None of the patients had received treatment for the virus, and all of the patients infected with the mutated strain of HIV developed AIDS within three years.

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While fast progression of HIV to AIDS is usually the result of the patient's weak immune system rather than the particular subtype of HIV, what's happening in Cuba is different.

"Here we had a variant of HIV that we found only in the group that was progressing fast. Not in the other two groups. We focused in on this variant [and] tried to find out what was different. And we saw it was a recombinant of three different subtypes."

The new variant, named CRF19, is a combination of HIV subtypes A, D and G.

HIV normally infects cells by attaching itself to what is called a co-receptor, and the transition to AIDS usually occurs when the virus switches -- after many years -- from co-receptor CCR5 to co-receptor CXCR4. The new strain makes the switch much faster.

The variant has been observed in Africa, but in too few cases to be fully studied. Researchers said the strain is more widespread in Cuba.

While the aggressive form of HIV responds to most antiretroviral drugs, people may not realize they have AIDS until it's too late for treatment to do any good. Vandamme said it's vital for people having unprotected sex with multiple partners to be tested for HIV early and often.