Happy World Health Day, everyone! This year, the World Health Organization (WHO) is focusing on the education and prevention of vector-borne diseases – those that are spread by mosquitos, flies, ticks and other insects. It’s a topic you probably don’t think about on a daily basis, but it is an important one – close to 1 billion people are affected by vector-borne diseases every year, many of which can be extremely debilitating, or fatal.
While these diseases have historically affected populations living in extreme poverty near the equator, many vector-borne diseases have begun spreading to new parts of the world, including the United States.
Take dengue fever, for example. Dengue, or “breakbone fever,” is a rapidly spreading, mosquito-borne, tropical disease similar to West Nile.
Dengue can cause extremely high fever and severe pain in the head and muscles (among other awful symptoms), and now because of increased international travel and environmental changes, dengue has recently appeared in places like Puerto Rico, Texas and Florida. That’s too close for comfort, if you ask me!
To add insult to injury, there really is no good prevention or treatment method available — but that very well might change.
Several vaccines for dengue fever are currently in clinical trials, and it looks like we’re getting close. The leading candidate is wrapping up Phase III clinical trials this year. If results are successful, it would be the culmination of roughly 60 years of research.
Developing a vaccine candidate for dengue hasn’t been easy. First, there is no animal disease model for dengue, so the testing process becomes increasingly difficult. Second, the virus itself is complicated. Infection with one type of the virus usually produces life-long immunity, but only to that one type of dengue virus. This isn’t unique to dengue – we see this type of specific protection with a few other vaccine-preventable diseases. What is especially challenging about our immune system’s response to dengue is that protection against one type seems to make infections with a second (or third or fourth) type of dengue virus much more severe and dangerous. Because of this, any vaccine against dengue would have to protect against all four types.
It’s an uphill battle, but thankfully one we could be winning. In spite of these challenges, remarkable progress has been made in recent years, and once it is fruitful, the vaccine could prevent 50-100 million cases of dengue fever worldwide every year.
So, today, in honor of World Health Day, take a moment to reflect on the progress we’ve made and are making in the field of immunization.
… And maybe also stock up on bug spray!