Untreated HIV infection progresses to AIDS quicker in Thailand

The progression from HIV infection to AIDS and death from AIDS is more rapid in untreated young men infected with HIV-1 subtype E living in Thailand than in HIV-positive individuals with HIV-1 subtype B infection living in the United States and Europe, according to researchers from the Johns Hopkins Bloomberg School of Public Health, the Armed Forces Research Institute of Medical Sciences and Chiang Mai University in Thailand.

The researchers tracked the length of time between HIV infection and AIDS among young Thai men. They also studied the death rate of the men 5-7 years after their HIV infection, which was higher when compared to their counterparts in developed countries. The study is published in the May 1^st 2004 issue of the Journal of Acquired Immune Deficiency Syndrome.

“The importance of this study is that it demonstrates the survival and progression rates of HIV/AIDS from the time of HIV infection in a developing country and documents that the progression is more rapid than in the US and Europe,” said Kenrad E. Nelson, MD, corresponding author and a professor in the Department of Epidemiology.

The researchers evaluated 235 men, who seroconverted within a six-month window during their two years of military service in the Royal Thai Army from 1991 to 1995. All of the men were drafted at the age of 21. After five to seven years, 156 were alive, 77 had died and 2 could not be located. The five-year survival rate of the study participants was 82 per cent.

The median time from HIV-1 seroconversion to clinical AIDS in the Thai study participants was 7.4 years. A 2000 study by the Collaborative Group on AIDS Incubation and HIV Survival, known as CASCADE, which studied over 13,000 persons in whom the time of HIV infection was documented, found that the median time after HIV infection to the development of AIDS for persons in Europe, North America and Australia was 11 years for study participants who were 15-24 years old.

The mortality rate of the Thai men was 56.3 deaths per 1,000 person-years, or 18 per cent five years after HIV-1 infection, as compared to a 9 per cent mortality rate among individuals living in developed countries in the West.

“These data will be very useful as treatment of HIV and opportunistic infections become more available for persons in developing countries. We will be able to measure the treatment’s effect on progression and survival after HIV infection,” said Dr. Nelson.

97.8% of the men were infected with HIV-1 subtype E, making it difficult for this study to provide any evidence about the relative effects of different HIV-1 subtypes on HIV disease progression.

The authors noted that the mean viral load within six months of seroconversion (74,000 copies/ml) was relatively high in comparison with Western studies of injecting drug users and haemophiliacs and also in comparison with individuals in the US Multicenter AIDS Cohort Study infected through sexual intercourse.

They also note the absolute CD4 cell count in HIV-negative young men was lower than for comparable men in the US MACS cohort (746 cells/mm³ vs 988 cells/mm³), and the authors suggest that lower baseline CD4 counts may provide one explanation for more rapid disease progression.