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Dengue Track: How Mapping the Spread of Disease May Help to Stop It
Dengue is a notoriously malicious mosquito-borne virus that has seen an uptick in recent decades with the expansion of urban environments. But a new tool called Dengue Track is trying to change that.

Dengue fever causes flu-like symptoms, minor bleeding and a characteristic full-body rash. The disease used to be confined primarily to tropical regions, but the World Health Organization estimates that about half the global population is now at risk. It is rarely fatal but nonetheless constitutes a leading cause of illness and death among children in some developing countries. Though a vaccine has been developed, its use has only been approved in three countries so far, and it is not yet widely available anywhere.

Dengue is a disease that is uncommonly hard to fight. Because it has an incubation period of four to 10 days, mosquitos can be spreading it in an area for weeks before officials start to realize that they have an epidemic on their hands. What’s more, as globalization intensifies and people and goods travel more broadly than ever, it’s nearly impossible to keep infections localized or to judge where they might develop next.

Illnesses that, like dengue, are transmitted by blood-sucking insects are called “vector-borne” diseases, and when vaccines are not available, the only way to protect human populations is through methods known collectively as “vector control.” These include strategies for reducing the insects’ breeding areas, creating tools like nets to keep them away from vulnerable people or killing them with pesticides.

Vector control, however, is most effective when the movement of the disease can be plotted on a map. The trouble is that dengue, which is most prevalent in developing countries around the equator, is dramatically underdiagnosed and underreported, and systems to share what little information there is are inefficient, unstandardized, or nonexistent.

Dengue Track, a crowdsourced tool that tries to map the epidemiology of the disease, is an initiative from an organization called Break Dengue. Drawing information from cell phone conversations, social media, and an online chat system, it plots cases of the illness across the globe to try to predict where it may surface next.

It is a low-cost method that relies on tools common in developing countries, where only one-third have access to the internet but over 95 percent own mobile phones. This means that it is particularly well-suited to places where the national health system does not have the ability to track outbreaks itself.

“Thousands of lives are lost every year in developing countries for failing to detect epidemics early because of the lack of real-time data on reported cases,” said Lakshminarayanan Subramanian, a professor at New York University who helped to develop Dengue Track. This app might prove a useful model for identifying such epidemics early in the game and taking the appropriate steps to head them off.

Madeleine Read

Photo: Flickr

mosquito_borne_virus
Chikungunya is not a term commonly recognized by the average American. The mosquito-borne virus was originally found in Tanzania in 1952, though it is suspected to have been circulating in the region for many centuries. Chikungunya is transmitted to humans by mosquitoes, and has been predominately concentrated in countries in Africa, Asia and the Indian subcontinent until quite recently.

Within the past week, the virus has been diagnosed in patients from several states in the U.S., including Indiana, Florida and North Carolina. These cases appeared after a major outbreak in the Caribbean that has affected thousands in the past few months.

While chikungunya is rarely a fatal disease, it can cause intense pain, which sometimes lasts for months. The main symptoms are fever and joint pain, though it can be accompanied by nausea, headache and fatigue as well. The World Health Organization states, “the disease shares some clinical signs with dengue (fever), and can be misdiagnosed in areas where dengue is common.”

The mosquito-borne virus is most common in areas close to mosquito breeding sites. The New York Daily News says that cases of the virus will continue to rise in Haiti due to large amounts of standing water left in open containers, which are “used in many Haitian homes that lack running water.” The WHO says that the virus spreads by bites from infected female mosquitoes. Symptoms usually begin to show four to eight days after the bite.

CNN reports that 25 to 28 American travelers bring the virus back to the U.S. after traveling to high-risk areas abroad. The New York Daily News affirms that the latest cases in the U.S. were not from local mosquitoes, but were “carried by recent travelers to the Caribbean where the virus is raging.”

The outbreak in the Caribbean has been troubling internationally, as tourist destinations like St. Martin could act as a hub for this epidemic, says The New York Times.

The Oxford Journals recognize that though the disease does not typically have a high death toll, in developing nations, “the epidemics resulted in significant morbidity and taxed the health care and public health infrastructure.”

Reducing the outbreak of chikungunya presents a challenge to the global community. Rural villages in African and Caribbean countries do not have access to running water, which creates the need for standing water sources. The risk of attracting mosquitoes increases under these conditions, and therefore the risk of disease goes up as well.

There is currently no vaccine or cure for chikungunya. According to the WHO, treatment aims to alleviate symptoms, usually using anti-pyretics (fever reducers), optimal analgesics (painkillers) and fluids. Travelers to high-risk areas are told to be cautious and protect exposed skin with clothing and bug spray. However, very few recommendations have been made for those who live in the afflicted areas. Unfortunately, reducing the number of cases in such areas would require major overhaul of health care systems and vast improvement of living conditions. Hopefully, the future will bring a vaccine and the social change needed to reduce the spread of this epidemic.

— Bridget Tobin

Sources: CNN, NY Daily News, NY Times, Oxford Journals, WHO
Photo: USA Today