HIV's ancient 'cousin' is ravaging Australia and could spread worldwide

HIV's ancient 'cousin' is ravaging Australia and could spread worldwide
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Central Australia is being ravaged by an epidemic of human T-cell leukemia virus type 1, or HTLV-1. A staggering 40 percent of adults in rural Australia are infected. This epidemic is in addition to the estimated 10-20 million people infected with HTLV-1 globally.

Ten percent of people infected with HTLV-1 will develop certain kinds of cancer, lung disease and chronic degenerative diseases such as adult T-cell leukemia/lymphoma, bronchiectasis and HTLV-1-associated myelopathy/tropical spastic paraparesis. Further, the HTLV-1 virus weakens the immune system, increasing the chances that those infected will develop other illnesses, including HIV.

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The prevalence rate in rural Australia is significant cause for concern. The virus has no cure, no vaccine and receives minimal funding or global attention. This epidemic highlights why global health funding to neglected issues continues to be critical.

 

A retrovirus with some similarities to HIV, HTLV-1 is transmitted through sexual contact, breastfeeding, blood transfusions and contaminated needles. Those infected are asymptomatic years after initial infection, so carriers can unknowingly infect others. It can’t be transmitted through casual contact like sharing water glasses or shaking hands. Yet it’s a virus we have precious few means of tracking.

The HTLV-1 virus is present world-wide, particularly in southern Japan, the Caribbean, parts of South America and Africa and nodes of infection in the Middle East, Australia and Melanesia. In some highly-populated areas of North and East Africa and Asia, we have no idea how prevalent the virus is, so prevalence is likely much higher than estimates.

While the wider prevalence of HTLV in the United States is unknown, the virus is here. Seroprevalence of HTLV-1 and related HTLV-2 is only 0.016 percent amongst voluntary blood donors in the United States.  

Yet, a study of new blood donors in the United States from 2000-2009 argued that actual prevalence is likely higher, because blood donors are rigorously screened to exclude individuals who engage in high risk behaviors. That study also revealed that black and Asian women over age 40 were disproportionately infected in the United States, possibly due to immigration from endemic areas like Japan, the Caribbean or sub-Saharan African countries.

While the United States screens blood donations for HTLV types 1 and 2, given the low prevalence of these viruses, the high cost of testing and the number of organs testing false positive, in 2009 the government eliminated requirements for HTLV-1/2 testing on organ transplants, although some transplant tissues remain routinely tested.

Like HIV, HTLV-1 primarily affects minority populations at home and abroad. In Australia, indigenous communities with access to fewer health services are disproportionately affected. The same is true in the United States, where African Americans and immigrants are disproportionately affected. Like HIV, injection drug users make up a significant proportion of HTLV-1/2 infections in the United States. There is a long history of neglecting prominent health issues that affect minority or poorer populations. Those affected by HTLV-1 are no exception.

While HTLV-1 does not spread as easily as HIV, from a public health standpoint, some of the primary transmission routes — sexual contact and mother-to-child transmission — should give us pause. Unlike tropical diseases such as malaria, which depend on certain environmental factors to spread, sexually transmitted diseases can spread beyond isolated populations, particularly in an increasingly globalized world. Indeed, global travel is precisely how HIV was brought to the United States.

Furthermore, a variety of structural factors make certain populations more at risk for a disease like HTLV-1, such as poverty, racial inequalities and lack of access to health care and education. Combining transmission routes and those structural factors with a lack of adequate screening mechanisms for the disease is a recipe for a public health disaster.

Bringing additional attention to HTLV-1 is not just the moral thing to do; from a public and global health standpoint it’s the economically prudent thing to do so that the virus doesn’t spread more widely. Indeed, experts agree for every $1 spent on global health there is up to a 20-fold benefit.

Recent research demonstrates good possibilities for creating an HTLV-1 vaccine and the Global Virus Network already has an HTLV-1 Task Force aiming to mobilize funding and experts to develop treatments and vaccines for the virus. What is needed now is significant global health funding and attention to make that goal into a reality.

Noelle Sullivan is an assistant professor of instruction in global health studies at Northwestern University. You can find her on Twitter: @ncsullivan.