Tick-borne diseases are an ever-present public health threat in the U.S., with several trends deserving attention. According to the Center for Disease Control and Prevention (CDC), these trends include increases in reported disease cases, expansion of disease and tick ranges, identification of new pathogens, and discovery of new tick species.
In recent years, research in these areas has shed light on several changing or emerging tick-borne diseases and pathogens. Keep reading to learn more about them.
Five Emerging Tick-Borne Diseases & Pathogens
1. B. miyamotoi disease
As discussed elsewhere on Tick Talk, one of the major new tick-borne diseases of note is what some are calling Borrelia miyamotoi disease.
Named for the species of Relapsing Fever Borrelia that causes it, B. miyamotoi disease closely resembles Tick-Borne Relapsing Fever, or TBRF. In fact, some in the medical field refer to B. miyamotoi disease as hard tick TBRF, since it is the only Relapsing Fever Borrelia known to be spread through hard ticks of the genus Ixodes – the genus that contains blacklegged ticks, lone star ticks, dog ticks, and other ticks responsible for most tick-borne diseases in North America. Specifically, B. miyamotoi disease is carried by both the Western blacklegged tick and Eastern blacklegged tick (a.k.a. deer tick), which are also responsible for Lyme disease.
An engorged soft tick
Meanwhile, other TBRF-causing Borrelia are spread through soft ticks of the genus Ornithodoros. These ticks are anatomically distinct from hard ticks and can feed (and transmit disease) much more quickly – within 15 minutes, in some cases.
Yet because soft ticks tend to be associated with the geographical region west of the Mississippi or with rustic, rodent-infested cabins, many people who live in the eastern U.S. and/or have not had exposure to soft ticks may not be aware that their symptoms could still be caused by TBRF. (Ticks in the South and Southeast also carry Borrelia that cause TBRF, though not necessarily B. miyamotoi.)
So, it’s important to understand that even if it is unlikely you were bitten by a soft tick, it is still possible that you’ve been infected with Relapsing Fever Borrelia. It is also possible to be infected with both Lyme and TBRF from the same tick bite. Like Lyme, TBRF becomes much more complex to treat the longer it goes undetected.
There are tests, such as glpQ, that might identify B. miyamotoi, but these tests target only one protein and therefore are not very sensitive. IGeneX tests for B. miyamotoi in addition to other strains of Relapsing Fever Borrelia.
2. B. mayonii Lyme
Borrelia mayonii is the most recently discovered type of Borrelia that causes Lyme disease. Discovered around 2016, the pathogen is increasing in the Northern Midwestern U.S., and – like other Lyme-causing Borrelia – is found in the Eastern blacklegged tick (deer tick).
B. mayonii is one of at least 18 classifications of Lyme-causing bacteria that have been discovered to date. Its increasing threat in the Northern Midwest is another reminder that when testing for Lyme, it is crucial to test for all major types of Borrelia present in the U.S. Unfortunately, CDC-recommended tests (ELISA and Western Blots) typically only test for one or two types, leading to many undetected cases of Lyme disease.
3. E. ewingii infection
Another emerging tick-borne disease listed in the American Society for Microbiology article linked above is Ehrlichia ewingii infection. E. ewingii is one of five species of the bacteria Ehrlichia that infect humans. While most cases of Ehrlichiosis (HME) are transmitted by the closely related bacteria E. chaffeensis, E. ewingii is increasingly common in the Midwest. It is therefore crucial that doctors also test for E. ewingii when a patient presents with Ehrlichiosis symptoms.
Both E. ewingii and E. chaffeensis are carried by the lone star tick, an aggressive hard-bodied tick that is most common in the Southwest, Southeast, Central South, and Midwest but is spreading geographically.
Note: Ehrlichiosis disease is also less commonly spread by the bacteria E. muris eauclairensis, which is carried by the Eastern blacklegged tick (deer tick). However, the CDC reports that this bacteria is mostly a threat in Wisconsin and Minnesota.
4. Bourbon virus disease
In addition to bacterial infections, ticks can also spread viral infections. Unfortunately, such diseases cannot be treated with antibiotics, making tick prevention measures all the more important. One of the most well-known tick-borne viruses is Heartland virus, which is typically reported in the Midwest and the South, and cannot be cured but only addressed with supportive treatment, sometimes including hospitalization.
Since 2017, there have been increasing reports of a closely related disease – Bourbon virus disease. The disease can cause symptoms similar to those of Heartland virus, such as fever, tiredness, rash, headache, body aches, nausea, and vomiting. It can also be fatal.
More research is needed to fully understand this emerging tick-borne disease.
5. Powassan virus lineage 2
Another virus carried by ticks is the rare but potentially fatal Powassan virus. This virus is broken down into Powassan virus lineage 1, which has historically been responsible for cases of Powassan virus in the U.S., and Powassan virus lineage 2, sometimes called Deer Tick Virus.
Powassan lineage 2, which along with lineage 1 can also be fatal, is considered rare but is also suspected to be vastly underreported because of a lack of diagnostic testing for this specific pathogen.
Like Heartland virus, Powassan virus cannot be treated with antibiotics. To prevent hospitalization or even death from Powassan viruses, take measures to prevent tick bites in the first place.
The need for accurate testing
Research on emerging tick-borne diseases creates new challenges for diagnostic testing. Though tick prevention practices can reduce the risk of contracting disease, ticks can be difficult to see or locate once attached, and some diseases can be transmitted quite quickly.
The good news is that bacterial tick-borne diseases are treatable and it is possible to recover – but only if the disease is caught and treated in a timely manner. Unfortunately, too many tick-borne diseases still slip through the cracks of today’s tests.
IGeneX is at the forefront of diagnostic testing for tick-borne diseases, always working to improve the sensitivity and accuracy of our tests. Learn more about testing with IGeneX today.