Vector Borne Disease Transmission in the US
When imagining the world's deadliest animals, pictures of venomous snakes or sharp-toothed sharks come to mind. Globally malaria, which is transmitted by mosquitoes, is responsible for millions of deaths each year (2). While it's not as prevalent in the US, other vector borne diseases like Zika, Dengue, West Nile, Lyme, Rocky Mountain Spotted Fever, and the plague (yes, the plague) are a problem (3).
Mosquitos—Zika,West Nile and Dengue
You may have heard about Zika in the news, as the first cases of transmission in the US in 2016 made national headlines (4). Zika is transmitted primarily through mosquito bites, but can also be contracted through sex with an infected person. The illness is characterized by fever, joint pain, eye-redness, and a rash. Zika can also be transmitted to a fetus through the mother, and this can lead to microcephaly (small head) and other severe birth defects (5). The CDC recommends that expectant mothers, women aiming to become pregnant, and their partners refrain from traveling to areas with Zika outbreaks and take extra precautions to avoid mosquito bites. You can find additional information regarding the CDC's current travel recommendations here.
In the US West Nile virus is the leading cause of mosquito-borne disease, with cases in all 50 states. There are also smaller and limited outbreaks of Dengue in the US as well. Both illnesses are similar in symptom profile: fever, rash, vomiting, and bodily aches and pains. In rare cases, both can become serious, and even fatal, if untreated. Severe Dengue presents with bleeding in the nose, gums, or vomit, and severe West Nile presents with nervous system symptoms such as meningitis (brain inflammation), convulsions, tremors, etc. Similar to Zika, Dengue is typically contracted from travel to US territories with some transmission occurring locally in Southern US states. West Nile transmission, however, is widespread throughout the continental US (6).
Ticks—Lyme Disease and Rocky Mountain Spotted Fever
Lyme Disease is the most common vector borne disease in the US accounting for roughly 60% of reported vector-related cases (6). Lyme-infected ticks are found throughout the US, but are most abundant in the Northeast (7). When an infected tick bites, it takes about 36-48 hours of attachment to the body to transmit the disease (7), so vigilance is key to avoiding Lyme! About a week after the bite, most (but not all!) will notice the characteristic "bulls-eye" rash. The other symptoms include swollen lymph nodes, fever, chills, and muscle and joint pain. Pay attention to your body; early treatment of Lyme leads to complete recovery, but leaving it untreated can lead to cases of "chronic Lyme" where symptoms can flare-up long after infection (7).
Rocky Mountain Spotted Fever (RMSF), although less common, can be VERY serious, and deadly if not treated early. RMSF symptoms include a fever along with headaches, upset stomach, and often a splotchy rash (8).
Lyme and RMSF not only affect humans, but can be painful infections for our furry companions. Be sure to check yourself and pets for ticks after being outdoors, especially in woodsy areas! Proper removal and testing of ticks will help with early detection and allow you to enjoy the outdoors this summer!
Although uncommon now with around 15 cases per year in the US, the disease that infamously ravaged Europe's population actually still exists. Plague is transmitted through contact with infected rodents, and bites from infected fleas. Concentrated in rural parts of the Western US, cases present with fever, chills, weakness, and extremely swollen lymph nodes. Prompt medical treatment is crucial for the prevention of serious complications; so, look out for symptoms, especially if your pets are scratching!
US Trends and Climate Change
Occurrence of these diseases in the US has more than tripled between 2004 and 2016 with more than 640,000 reported cases (which is likely a large underestimation) (6). The amount and habits of disease carrying critters highly depend on environmental factors such as temperature, rainfall, and humidity. Many vectors thrive in warm, humid, climates and breed in flood reservoirs. As our planet warms and extreme storms become more abundant, scientists predict a continued increase in vector-borne diseases and possible reintroduction of Malaria or Yellow Fever to the US (6, 10). The Fifth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) state vector borne diseases have emerged in new areas, as more locations become suitable habitats. The "mosquito season" has increased by an average of 40 days in most major US cities. Also, as climate change-induced disasters lead to the mass migrations of people from tropical areas, pathogen carrying pests will have the opportunity migrate as well (11). Caring about our Earth is caring about our health!
How to Protect Yourself
Enough of pesky bugs and scary symptoms— here is how you can enjoy your summer safely!
1) The most crucial way to protect yourself is to seek medical care if you have any of the symptoms listed above after you've spent time outdoors
2) Insect Repellant! Keep the bugs from biting with an effective bug spray!
3) Wear long sleeves and pants outdoors when possible
4) ALWAYS check for ticks after venturing through wooded areas
5) Practice proper lawn/yard care such as mowing the grass frequently, keeping wood/bush trimmings in dry, isolated areas, and eliminating standing water sources near your home
6) Be diligent when traveling! Do your research and take caution when going to equatorial areas
7) Protect your pets! Additional information on pet flea and tick control can be found here.