Thai strain of HIV now predominant in Philippines

MANILA, Philippines - A more aggressive strain of HIV was seen among infected Filipinos and this could be one of the reasons for the significant increase in new infections, a study of the National Institute of Health (NIH) at the University of the Philippines-Manila showed yesterday.

Edsel Salvana, director of the NIH’s Institute of Molecular Biology and Biotechnology, said the molecular epidemiology of HIV in the Philippines has changed over the last decade.

The more aggressive Thai strain or CRF01 AE is the “predominant subtype” of HIV in the country, Salvana told The STAR.

A study done before 2003 showed that the subtype B or the United States/Western European strain was the most common strain of HIV in the country. 

“The HIV strain commonly found in the Philippines has changed. Before, we were usually seeing the American strain but somewhere along the way, based on our study, it became the Thai strain,” he said.

Salvana cited a study of the NIH in 2013 that involved 81 HIV patients who were not yet on treatment. The study aimed to determine whether local molecular subtypes of HIV have changed over the last decade.

Salvana said the patients, who were all males and almost of the same age, acquired HIV around the same time but the level of their CD4 count differed. 

CD4 or CD4 T lymphocytes are the cells in the body being attacked by the virus and the strongest predictor of the progression of HIV into AIDS. The normal count is 500 and above.

The study showed that 75 percent of the patients were infected with the Thai strain, which was discovered in Cuba. Twenty-two percent were infected with the US/Western European strain.

The study also suggested that the Thai strain progressed faster into AIDS than the US/Western European strain, according to Salvana.

“Those with Thai strain had lower CD4 count at 233 while those infected with US strain had 350 CD4 count,” he said.

“Usually, the time progression into AIDS of the US strain is eight to 10 years but in the Thai strain, it seems to be four to five years only. The Thai strain has higher rate of transmission,” he added.

HIV cases rising

Salvana said the Philippines is one of nine countries with rapidly increasing cases of HIV infection. 

The annual reported cases of HIV in the country have increased 37-fold in the last decade. Sexual transmission still accounts for over 95 percent of cases, and a major shift from heterosexual to MSM (men having sex with men) transmission has occurred.

Salvana said the study indicated that the sudden increase in HIV cases in the Philippines could be attributed to the Thai strain.

“At this time, the treatment for both strains is the same. If the question is whether the Thai strain is more difficult to treat or not, no one can answer that now. We are still studying that,” he said.

Based on the HIV/AIDS registry of the Department of Health (DOH), 26 new HIV/AIDS cases were documented every day in 2016. The figure is up from one case in 2008; four cases in 2010; nine cases in 2012 and 17 cases in 2014.

The DOH recorded a total of 39,622 HIV cases, including 3,665 AIDS, from January 1984 to December 2016.