Small world: Study of HIV subtype’s global spread shows impacts of tourism, migration, policies

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The subtype that comprises 5 percent of HIV-1 infections globally traveled from Africa to Thailand where it was identified in 1989. From there, it spread around the world.

In 1991, when Thailand became home to 143,000 new HIV infections, public health officials acknowledged the seriousness of the country’s epidemic, and tackled it with the then new 100 percent condom campaign. The measure proved effective enough that, 10 years later, HIV incidence in Thailand had been decimated, dropping to fewer than 14,000 new infections. The impact of HIV in Thailand, and how it had spread as quickly as it did there, however, continues to be felt around the world, a study tracing an HIV subtype that was central to Thailand’s epidemic indicates.

JID113The study is described in Global Dispersal Pattern of HIV Type 1 Subtype CRF01_AE: A Genetic Trace of Human Mobility Related to Heterosexual Sexual Activities Centralized in Southeast Asia, published last week in the Journal of Infectious Diseases.

The HIV-1 subtype that the study traces originated in Central Africa during the 1970s, according to the article’s authors, but was not identified until 1989, when it was found among among sex workers in northern Thailand. After that it became part of a large epidemic in Southeast Asia, making up nearly 80 percent of infections there. Descended from the most widespread of the four genetic groups of the virus that were separately transmitted from simians to humans, and from one of that group’s nine genetic subtypes, CFF01_AE is a “recombinant” or combination of two subtypes, and is referred to by the authors as “one of the successfully spreading recombinants.” Now, estimated to comprise 5 percent of HIV infections worldwide, it has been found in North America, Europe, Central and West Africa, Asia and Australia. The authors used a global data set to trace the subtype’s journey around the world. Grouping the information they found by country, they wrote, revealed that Thailand had exported the epidemic of the subtype to 17 of the European countries they examined, with the highest ratios of in the United Kingdom, Slovenia, Switzerland, and Austria  and also going to Canada, the United States, Japan, Singapore and Taiwan, Hong Kong, South Korea, Afghanistan, Iran Pakistan Indonesia, Malaysia, Myanmar and the Philipines.

The authors attribute Thailand’s location “at the crossroads of Africa, Asia and Oceania,”along with its  popularity as a tourist destination, particularly for sex tourism as well as migration from the country to North America and Europe are some of the reasons for the widespread dispersal of the virus from the country.

The authors also note that “Japan seems to have had an important role in viral dissemination,” having both imported and exported the virus. Leading exporters of the virus in Europe they say, were Sweden and Finland.

 

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