Thanks to Dr. Peter Hotez for tweeting the link to this important (and prophetic) 2008 article in PLOS Neglected Tropical Diseases: Why Arboviruses Can Be Neglected Tropical Diseases. Excerpt:
Too often, the environmental conditions around urban slums result in perfect larval development sites that will easily support endemic mosquito cycling of disease. Aedes aegypti, the primary vector of many important arboviral diseases, such as yellow fever, dengue, and chikungunya, has been difficult to eradicate and is responsible for the resurgence of many of these diseases. Infections that were once under control, such as yellow fever and Japanese encephalitis, are now capable of returning with a vengeance to poor neighborhoods in both wealthy and impoverished nations. The current outbreaks of yellow fever in Paraguay and Brazil demonstrate our inability to control the resurgence of these arboviral diseases. Practices to escape poverty are also to blame: the spread of yellow fever in Africa and its reemergence in Brazil has been linked to deforestation.
Access to health care is another important issue for the neglected viral diseases. Although many viral infections are acute in nature and often resolve spontaneously, poor patients come to medical care late in the course of disease, as is often seen with dengue infections. This late presentation leads to worsened disease outcomes than for patients who are financially better off and present sooner.
Because viral NTDs occur more commonly in those who are poverty-stricken, it can be difficult to decipher all the ways in which the diseases contribute to poverty. Like other NTDs, viral NTDs can lead to debilitating chronic sequelae that impact individual work productivity and family income. RVFV, for example, can lead to permanent visual loss or impairment, which can have a great impact on long-term productivity and quality of life ,. Importantly, viral NTD outbreaks generally lead to loss of life, family hardship, and distress. Japanese encephalitis is an extreme example, where case fatality rates can be as high as 30%, with one-third of survivors suffering severe neurological sequelae . Because epidemics of arboviruses often receive notice only when they are acute and massive, the public loses sight of ongoing transmission, which has a significant daily impact on the life of people living in endemic countries.
Too often these diseases are ignored and neglected because they have not yet impacted the lives of those living in affluent areas. Many of these diseases are understudied and go unnoticed until outbreaks affect North Americans or Europeans, as recently displayed in the recent surge of interest in chikungunya after outbreaks on the Indian Ocean islands, a favorite European vacation destination.
Certain populations within these neglected diseases also go unnoticed, such as the impact chikungunya and dengue have had on neonates and children. The lack of research contributes to our simplified understanding of these infections and our inability to decipher one infection from another. For example, the understudied Mayaro virus may constitute a significant portion of dengue-like illness cases in Latin America.
As more emphasis is placed on defining the true cost of the NTDs, the real-world problem of concurrent and overlapping infections must be re-evaluated. Although the neglected tropical viral diseases are part of poverty in tropical nations, their full impact is likely not to be determined in isolation, as arboviruses constitute a part of the larger health problem in resource-poor settings.
More research, more insight, and more discussions regarding these important NTDs and the populations that suffer from them will be necessary to fully define the impact of neglected tropical viruses in the regions where they persist.