The Globalization of Infectious Diseases

By Rachel Sachs

The recent arrival of Ebola in the United States has captured the attention of both the public and the media for many reasons.  One key reason is that Ebola is making many people realize for the first time that serious diseases which were formerly confined largely to developing countries have the potential to spread more widely across the globe.  But Ebola is not the first infectious disease to spread in this way, and it’s valuable for Americans to realize that many diseases which are often viewed as existing only in developing countries are already present in the developed world, due to a complex set of factors including migration and climate change.

Specifically, serious diseases transmitted by insects like chikungunya, dengue fever, and Chagas disease are already here in the United States.  I blogged here in August about DARPA’s prize to predict the spread of chikungunya, and the CDC’s estimates suggest that the disease may be finding a foothold in this country, with 11 locally-transmitted cases in addition to the more than 1500 travel-associated cases confirmed so far in 2014.  Compared to an average of just 28 cases per year since 2006, the spread is concerning.  Scientists also contend that dengue fever, a disease with similarly debilitating symptoms, is now endemic to Florida.

The case of Chagas is even more dramatic.  Categorized by the CDC as a “neglected parasitic infection,” it is estimated that 300,000 infected people live in the United States.  That’s ten times as many people as are diagnosed with ALS, a disease which has made much more of a mark on the public consciousness.  Chagas’ impact (both human and economic) on the United States’ health system is and will continue to be extremely costly, with one study estimating the economic cost to the United States at roughly $900 million annually.  Some of these costs are indirect — for instance, donated blood must now be screened for the presence of the parasite, to prevent its transmission.  But most are direct.  Over the long term, Chagas can cause severe, even fatal damage to the heart and gastrointestinal tract.  Read More