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CDC: Illnesses from ticks and mosquitos tripled over 13 years

Data: Centers for Disease Control; Graphic: Chris Canipe/Axios

Illnesses spread by mosquitoes, ticks and fleas have greatly expanded in both infection rates and in geographical reach, with more than 640,000 cases reported and 9 new germs discovered between 2004–2016, officials from the Centers for Disease Control and Prevention said Tuesday.

Why now: While CDC director of vector-borne diseases Lyle Petersen declined to blame climate change, he said warmer temperatures are escalating the issue along with other factors like increased global trade, patterns of movements of people and animals, and the spread of people — and deer — into rural areas.

Why it matters: "To effectively reduce transmission and respond to outbreaks [we] will require major national improvement of surveillance, diagnostics, reporting, and vector control, as well as new tools, including vaccines" against Lyme disease, dengue, chikungunya, and Zika, CDC said in its Vitals Signs report.

Why we'll hear about this again: Petersen said "all of of these [mosquito-borne] diseases are just a plane flight away." He pointed to the introduction into the U.S. of West Nile virus in 1999, chikungunya in 2014 and Zika in 2015. This "appears to be an accelerating trend," he says.

Higher temperatures are another factor to watch, Petersen said. As temperature heats up, ticks can move farther north and have a longer active season. Mosquito-borne disease outbreaks tend to happen during hot seasons since the heat makes them more active and accelerates the growth of the infectious agent too.

By the numbers, for 2004–2016:

  • CDC director Robert Redfield said more than half of the infections were from ticks (77% of the total) and 9 new germs (7 of which are from ticks) have been discovered since 2004.
  • CDC received reports of 642,602 cases of 16 diseases caused by bacteria, viruses, or parasites from mosquitos, ticks or fleas — but they say this number is grossly underreported. For instance, Petersen told reporters Lyme disease is believed to be 10 times higher than is reported, or roughly 300,000 cases.
  • Lyme disease accounted for 82% of all tick-borne cases, but spotted fever rickettsioses, babesiosis, and anaplasmosis/ehrlichiosis cases also increased.

What's next: People need to take precautions against ticks and mosquitoes, and state and local public health officials need to be proactive in prevention measures as well as better at reporting local incidences of vector-borne diseases, Petersen said.

Petersen said the federal government needs to help states develop better surveillance and monitoring tools. “We need to support state and local health agencies responsible for detecting and responding to these diseases and controlling the mosquitoes, ticks and fleas that spread them.”

Go deeper: See the CDC's disease-specific table, check out Congress' directives to CDC on Lyme disease and read how mosquitos carrying illnesses invade the U.S.