Dengue Fever, Climate Change & Puerto Rico

Dengue fever is increasingly being recognized as a major global public health concern, yet not enough is being done to address it, especially in places like Puerto Rico. It is endemic in more than 100 countries, and is expanding to new regions, including the United States. The World Health Organization reported a 30-fold increase in dengue incidence over the past 50 years. The emergence of dengue has resulted in considerable threats to population health with rising economic costs.

Dengue is spread by the Aedes mosquito by acquiring a blood meal from an infected host, and taking a subsequent blood meal from a susceptible host. Dengue causes flu-like symptoms, body aches, fever, diarrhea, vomiting, and rash, which can last up to a week but then the symptoms, most often, return as they are biphasic. The major challenge with dengue is that there are four strains. Infection with one dengue virus strain provides lifelong immunity to reinfection by that particular strain. However, getting dengue a second, third or fourth time by acquiring the other strains increases the likelihood of increased severity of the disease which can lead to hemorrhaging and death because antibodies developed from a previous infection cause enhanced viral uptake with a new infection by a different strain. The biggest challenge is to create a vaccine that can target all four strains.

While dengue constitutes the fastest mosquito-borne disease globally, it is an acute problem in Puerto Rico where they have flourished and the means to continue to do so are greater after Hurricane Maria, and the changing climate. Many parameters, including air and ocean temperatures, wind, and precipitation are showing trends. Such trends and associated extreme events, as we have seen by two powerful hurricanes (Irma & Maria) to hit Puerto Rico in the span of merely two weeks, are likely to continue to occur. Moreover, sea level rise could lead to the adaptation of freshwater mosquitoes to breed in saline waters which can influence dengue outbreaks. Many researchers suggest that the Aedes mosquitoes have excellent adaptation skills regarding rising temperatures and extreme conditions, therefore transmission intensity may be regulated by weather and climate.

The growth of dengue from a minor tropical illness to a disease of worldwide importance is a demonstration of the power that commerce, air travel, and globalization can have on global public health. So what happens in Puerto Rico has a direct impact on the United States, and beyond. Measures need to be put in place to take care of the environmental degradation from the aftermath of hurricane Maria, which has the great potential to breed more harmful mosquitoes.

The World Health Organization has a goal of reducing mortality and morbidity from dengue by 2020 by at least 50% and 25% respectively (using 2010 as the baseline). They are focused on forecasting when the next dengue outbreak may occur and how to get countries prepared for it. I believe the focus should not be on when the next dengue outbreak will occur, rather it should be on how can we eradicate dengue now? History has shown the outcome when we placed a focus on eradicating polio, smallpox, and yellow fever. Dengue should be no different.

The human suffering and social suffering brought on by dengue should cause everyone in the global health arena to take notice. In poverty-stricken areas like Puerto Rico, the burden of dengue puts a strain on the healthcare system, family members, and society as a whole. Even so, there has not been concerted action against dengue, which the World Health Organization readily admits. The rise in global temperatures should cause concern because if we don’t think of eradication now, we may reach a point where the problem of dengue is so far ahead of us, we will have to live with the consequences of neglect.


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