CDC Wakes Up: Illnesses from Mosquitoes, Ticks and Fleas on the Rise


The Centers for Disease Control (CDC) now says, illnesses from mosquito, tick, and flea bites have tripled in the U.S., with more than 640,000 cases reported during the 13 years from 2004 through 2016.  Nine new germs spread by mosquitoes and ticks were discovered or introduced into the United States during this time.

These findings are in the latest Vital Signs report by the CDC.

And I can say, ‘I told you so.’ I’ve been reporting on this for years. I don’t merit credit, I only happen to attend veterinary conferences.

Dogs (and in some instances cats) are a sentinel. And for several years, based on what veterinary parasitologists have told me and by following Companion Animal Parasite Council tracking, I know tick disease – in particular – is an epidemic. And we don’t even know the full extent of it as so much tick disease goes unreported in people and in pets. 

However, I do argue we can do more to protect dogs and cats from tick disease than we do for people. And we can do a better job of diagnosing exposure, specifically the use of a simple blood test, the Snap 4Dx Plus test (from IDEXX).

In a public statement CDC Director Dr. Robert R. Redfield said,  “Zika, West Nile, Lyme, and chikungunya—a growing list of diseases caused by the bite of an infected mosquito, tick, or flea—have confronted the U.S. in recent years, making a lot of people sick. And we don’t know what will threaten Americans next Our Nation’s first lines of defense are state and local health departments and vector control organizations, and we must continue to enhance our investment in their ability to fight against these diseases.”

CDC mapping of tick disease in people. I suggest the Companion Animal Parasite Council is ahead of the CDC

CDC scientists analyzed data reported to the National Notifiable Diseases Surveillance System for 16 notifiable vector-borne diseases from 2004 through 2016 to identify trends. Many infections are not reported or recognized, so it is difficult to truly estimate the overall cost and burden of these diseases.

There are many reasons for this and they vary widely. While veterinarians are  trained to think about tick disease (and as mentioned diagnostics are readily and inexpensively available), physicians may not think tick or mosquito spread disease or illnesses. Some physicians apparently don’t even believe the affects of tick disease are real. And insurance (no surprise) doesn’t cover all testing or treatments (some may considered experimental, but they do appear to help).

2018 forecast of Lyme disease in dogs, Companion Animal Parasite Council

In 2016, the most common tickborne diseases in the U.S. were Lyme disease and ehrlichiosis/anaplasmosis, though the list of illnesses caused by ticks gets longer every year. The most common mosquito-borne viruses were West Nile, dengue, and Zika. Though rare, plague comes from an infected flea. Fleas also spread Bartonella henselae (B. henselae) (cat scratch), tapeworm and other illnesses.

The increase in diseases caused by the bite of an infected mosquito, tick, or flea in the U.S. is likely due to many factors. Mosquitoes and ticks and the germs they spread are increasing in number and moving into new areas. Climate change (yes, it’s real) plays a significant role, so does the increase in wildlife in close proximity to people, and when it comes to Lyme not only are deer responsible so is one cute little mouse species – and that species has vastly increased their numbers.

White-footed mouse supports deer ticks and therefore Lyme


CAPC mapping has made this clear for years. So, for anyone attending veterinary conferences, all this comes as no surprise.

As a result, more people are at risk for infection. Overseas travel and commerce are more common than ever before. What’s not an issue for our pets so much is that a traveler can be infected with a mosquito-borne disease, like Zika, in one country, and then unknowingly transport it home. Finally, new germs spread by mosquito and tick bites have been discovered and the list of nationally notifiable diseases has grown, and I’ve reported on most of these.

Key findings from the CDC

  • A total of 642,602 cases of disease caused by the bite of an infected mosquito, tick, or flea were reported in the U.S. and its territories from 2004 through 2016.
  • The number of reported tickborne diseases more than doubled in 13 years and accounted for more than 60 percent of all reported mosquito-borne, tickborne, and fleaborne disease cases. Diseases from ticks vary from region to region across the U.S. and those regions are expanding.
  • From 2004 through 2016, seven new germs spread through the bite of an infected tick were discovered or recognized in the U.S. as being able to infect people.
  • Reducing the spread of these diseases and responding to outbreaks effectively will require additional capacity at the state and local level for tracking, diagnosing, and reporting cases; controlling mosquitoes and ticks; and preventing new infections; and for the public and private sector to develop new diagnostic and vector control tools.


In third world countries the CDC’s response has been to support a multi-modal approach to protect people. And the same appears to be true here, as outlined by the CDC.

  • Use an Environmental Protection Agency-registered insect repellent. []
  • Wear long-sleeved shirts and long pants.
  • Treat items, such as boots, pants, socks, and tents, with permethrin or use permethrin-treated clothing and gear.
  • Take steps to control ticks and fleas on pets.
  • Find and remove ticks daily from family and pets. []
  • Take steps to control mosquitoes, ticks, and fleas inside and outside your home. [ and]

Similarly, to protect pets, increasingly veterinarians are suggesting a similar double defense approach, such as Vectra 3D which repels mosquitoes combined with a traditional heartworm preventive product – the certainty of protecting against heartworm (and annoying mosquito bites) is clear. Regarding fleas and ticks, Vectra kills those too. For other tick products, a faster kill turns out to be important, and products that cover the right ticks in your geographic area. Your best bet, pay attention and speak with your veterinarian.