Issues Of The Environment: Washtenaw County And SE Michigan See Explosion In Tick Population

It’s a great time of years to get outdoors! But, there are some potentially harmful critters waiting for you. Ticks have expanded their habitat in Michigan, and there is a major increase in the populations in Washtenaw County and Southeast Michigan. WEMU’s David Fair checked in with Michigan State University entomologist Howard Russell to find out why that is and what we can do to keep ourselves and our pets safe. 

Overview

• As the COVID-19 pandemic winds down, many people are venturing out to enjoy recreation activities like camping and hiking that were missed during the shutdown. Unfortunately, 2021 is a very bad year for ticks. A decade ago, finding ticks in Southeast Michigan was uncommon. Today, any patch of tall grass should be approached with caution. 

• Weather changes, especially warmer, wetter winters, have allowed ticks to proliferate. With climate change, Michigan winters have had fewer periods of prolonged cold that could cause a die-back in tick numbers. Ticks also benefit from wet winters that keep leaf litter moist. Migratory birds are a common intermediate host for ticks that transmit disease, and climate change may also play a role by changing bird migration patterns,

• Populations of 5 species of ticks are on the rise in the greater-Washtenaw County region, the American dog tick and Blacklegged tick (responsible for Lyme disease) are the most common. Lyme disease first was recognized as endemic to Washtenaw County in 2016. It is caused by the bacterium Borrelia burgdorferi and is transmitted to humans through the bite of infected blacklegged ticks. Typical symptoms include fever, headache, fatigue, and a characteristic skin rash called erythema migrans. If left untreated, infection can spread to joints, the heart, and the nervous system. Lyme disease is diagnosed based on symptoms, physical findings (e.g., rash), and the possibility of exposure to infected ticks. Other species of ticks also transmit diseases, including Rocky Mountain spotted fever and tularemia.

• Howard Russell, Entomologist at the Department of Plant, Soil and Microbial Sciences at Michigan State University, still walks his dog through areas known to be tick habitat, but he carefully grooms his pets and inspects himself for ticks afterward. Wearing light colored clothing, tucking pants into socks, staying on trails and out of tall grass, and using permethrin or DEET repellents can help to prevent tick bites. If bitten, carefully remove the tick as soon as possible, take a photo for identification, and destroy it. Photos can be submitted to the Michigan Department of Health and Human Services for an ID, but due to the pandemic, they are not being tested for disease at this time. If you are unsure about what kind of tick you have encountered, take a photo and send it to Howard at [email protected] and he will get back to you as quickly as possible.

Ticks found in Washtenaw County

1. American dog tick (Dermacentor variabilis)

• Distribution: Widespread throughout Michigan forests and grassy areas
• Key Facts: These ticks are active from early May-November, and will bite both humans and companion animals.
• Diseases: Diseases associated with the American dog tick are rare in Michigan, but may include Rocky Mountain spotted fever and tularemia.

2. Blacklegged tick (Ixodes scapularis)

• Distribution: Emerging in Michigan
• Key Facts: Found on low forest vegetation, often along human and animal trails.
• Diseases: Lyme disease is the most common tick-borne disease in Michigan. Other rare diseases include: anaplasmosis, babesiosis, deer-tick virus, and ehrlichiosis.

3. Lone star tick (Amblyomma americanum)

• Distribution: Occasionally found in wooded and grassy areas across the state
• Key Facts: An aggressive biter of humans and companion animals, adult females have distinctive “Lone Star” mark
• Diseases: Ehrlichiosis, rocky mountain spotted fever, tularemia

4. Woodchuck tick (Ixodes cookei) 

• Distribution: Found most commonly on pets throughout Michigan
• Key Facts: Usually found near dens of skunks and woodchucks, will bite companion animals near animal dens and occasionally humans
• Diseases: Powassan encephalitis

5. Brown dog tick (Rhipicephalus sanguineus)

• Distribution: Occasionally found in Michigan.
• Key Facts: can uniquely survive and breed in indoor environments, has been associated with kennel, shelter, and breeding facilities. Good hygiene practices can prevent indoor infestations.
• Diseases: Rocky mountain spotted fever, canine babesiosis, canine ehrlichiosis (Source: *directly quoted* https://www.michigan.gov/documents/emergingdiseases/5commonticks_282020_7.pdf)

Lyme & Ticks – Lyme Disease in Washtenaw County

Washtenaw County is now confirmed as an area where Lyme disease can be transmitted. Lyme disease is spread by the bite of an infected blacklegged tick (Ixodes scapularis, also known as deer tick). All residents and visitors are urged to “fight the bite” against ticks and tick-borne disease. Transmission season for Lyme disease in Michigan typically occurs from May through August, with a peak in June. Frequent tick checks are important during this time of year. Prompt removal of ticks can prevent Lyme disease infection.

Lyme Disease Cases in Washtenaw County Residents

**Counts as of 3/19/2021**

Note: Case numbers reflect individuals who met the CDC criteria for confirmed and probable case classification for Lyme disease. In 2017, a suspected classification was added. Lyme transmission was confirmed in Washtenaw County in 2016. *These counts are preliminary and subject to change. 

Tick Identification

Note: The Michigan Department of Health and Human Services is no longer testing ticks for disease-causing agents. Ticks can be submitted for identification only. The state laboratory is focusing on COVID-19 testing and is complying with CDC recommendation regarding tick testing.

If you find a tick and would like to have it identified, you can send a photo of the tick via email. See the instructions on submitting a photo for identification or email [email protected].

You can also stop by either of our locations for a free kit to mail your tick to the state lab for identification. You can also submit a tick to the state without using a special tick kit. See the instructions on submitting a tick for identification. Note that ticks submitted to the state will only be identified – they will NOT be tested.

About Lyme Disease

Lyme disease is caused by the bacterium Borrelia burgdorferi and is transmitted to humans through the bite of infected blacklegged ticks. Typical symptoms include fever, headache, fatigue, and a characteristic skin rash called erythema migrans. If left untreated, infection can spread to joints, the heart, and the nervous system. Lyme disease is diagnosed based on symptoms, physical findings (e.g., rash), and the possibility of exposure to infected ticks. In the United States, an estimated 300,000 Lyme disease infections occur each year. 

Treatment & Prevention

Most cases of Lyme disease can be treated successfully with antibiotics. Patients treated with appropriate antibiotics in the early stages of Lyme disease usually recover rapidly and completely. Antibiotics commonly used for oral treatment include doxycycline, amoxicillin or cefuroxime axetil.

Steps to prevent Lyme disease include using insect repellent, removing ticks promptly, applying pesticides and reducing tick habitat. While it is a good idea to take preventive measures against ticks year-round, be extra vigilant in warmer months (April-September) when ticks are most active.

Tick checks and prompt removal are also important. In most cases, the tick must be attached for 36 to 48 hours or more before the Lyme disease bacterium can be transmitted. 

Avoid Direct Contact with Ticks

• Avoid wooded and bushy areas with high grass and leaf litter.
• Walk in the center of trails.

Repel Ticks with DEET or Permethrin

• Use repellents that contain 20% or more DEET (N, N-diethyl-m-toluamide) on the exposed skin for protection that lasts up to several hours. Always follow product instructions. Parents should apply this product to their children, avoiding hands, eyes and mouth.
• Use products that contain permethrin on clothing. Treat clothing and gear, such as boots, pants, socks and tents. It remains protective through several washings. Pre-treated clothing is available as well.
• Other repellents registered by the Environmental Protection Agency (EPA) may also be effective at preventing ticks. An insect repellent search tool: Find the Insect Repellent that is Right for You.

Find & Remove Ticks from Your Body

• Bathe or shower as soon as possible after coming indoors (preferably within two hours) to wash off and more easily find ticks that are crawling on you.
• Conduct a full-body tick check using a hand-held or full-length mirror to view all parts of your body upon return from tick-infested areas. Parents should check their children for ticks under the arms, in and around the ears, inside the belly button, behind the knees, between the legs, around the waist, and especially in their hair.
• Examine gear and pets. Ticks can ride into the home on clothing and pets, then attach to a person later, so carefully examine pets, coats, and day packs. Tumble clothes in a dryer on high heat for an hour to kill remaining ticks.
• To remove a tick, use tweezers and grip the body firmly and pull straight out of the skin. Do not twist the tick. After removing the tick, clean the bite area and your hands. If you choose to dispose of a live tick, submerse it in alcohol in a sealed bag or container, wrap tightly in tape or flush it down the toilet. Never crush a tick with your fingers. (Source: *directly quoted* https://www.washtenaw.org/1813/Lyme-Ticks)

The Role of Bird Migration and Climate Change in Tick Dispersal

The Centers for Disease Control and Prevention (CDC) recently announced that diseases spread by mosquitoes, ticks and fleas tripled between 2004 and 2016. More than 640,000 of such illnesses were reported during these years, including Zika, dengue, chikungunya, Lyme disease and plague. These diseases are known as vector-borne diseases, because infection of humans requires transmission of the microbe by an intermediate species. The CDC acknowledges that the US is inadequately prepared to diagnose and treat these expanding epidemics, which are fueled in part by climate change and its effects.

For example, migratory birds have been linked to the spread of West Nile virus, avian influenza virus, Lyme disease, and many other illnesses. Etc. etc.

Migratory birds have been linked to the spread of West Nile virus, avian influenza virus, Lyme disease, and many other illnesses. Climate change is altering the amount of suitable habitats for disease-carrying animals such as ticks. Even though many new habitats now provide ideal living temperatures for ticks, it would be difficult for them to physically move to these new areas without some help. Migratory birds facilitate the movement of ticks to new territories. Avian migration has opened the door for many diseases to spread over vast distances each year by carrying disease vectors such as ticks, or by the birds being themselves infected by the disease and spreading it to others as they migrate.

To see the effect of bird migration on the spread of ticks across America, Cohen et al. (2015) conducted a study that measured how many ticks are brought into America by migratory birds. They also screened the ticks for various microbes, including pathogens that cause spotted fever, and the bacterium that causes Lyme disease. In the spring of 2013 and 2014 they captured 3,844 birds, of 85 different bird species that were returning north for the summer. Out of these 137, about 3.56%, were infected with ticks. All of the ticks collected were either in the larva or nymph stage of development, and 67% of the ticks they collected were neotropical ticks, meaning they were from Central or South America. After screening the ticks for diseases, they found that 38 of the ticks were infected with some variation of the spotted fever bacteria, Rickettsiae, and that none of the ticks harbored Borrelia burgdorferi, the bacterium that causes Lyme.

The authors estimated that about 4 to 39 million neotropical ticks are brought to the United States each year. Although the ticks found in this study did not have Lyme, migratory birds are still introducing ticks to new habitats thus increasing tick populations across the country. Since the ticks they found were all larvae or nymphs, there was still a chance for them to become infected with Lyme, and spread it to future hosts. Ticks have three blood meals in their lifetime, one to help their development from larvae to nymphs, another for their transition from nymphs to adults, and finally, as adults before laying eggs. The Lyme bacterium or other pathogens are transmitted to ticks if one of their blood meal hosts is infected. Thus, the ticks that are transported to America on birds can still put humans at danger for Lyme disease, if they acquire their next blood meal from an infected host.

Ogden et al. (2015) conducted a somewhat different study examining the relationship between migratory birds and ticks. The study tracked how far north the birds were taking the ticks. They found that many birds went further north than their previous breeding sites when returning to Canada in the spring, and even went into territories beyond the tick’s climatic range (Figure 1). Even though ticks cannot currently survive in some of these areas, the increasing temperatures will make more and more of these habitats suitable over time. Climate change will also impact the migration routes of birds, and perhaps cause them to continue flying further north each year. Therefore birds will continue to bring ticks into new habitats, and the ticks will be more likely to survive in these northern areas as the temperatures continue to rise. Moreover, with rising temperatures, mice will also expand further north, possibly bringing the Lyme disease bacterium with them.

Ticks are very small, slow moving creatures; alone, it would be impossible for them to spread into new territories as far as northern Canada. However, ticks receive a lot of help from the small animals they latch onto, with organisms like migratory birds helping them cover vast distances. The actions of migratory birds amplify the effects of climate change on tick populations, and together they will help spread ticks into new territories. There can be little doubt that Lyme disease and other tick-borne diseases will follow. (Source: *directly quoted* https://www.globallymealliance.org/blog/lyme-disease-spread-migratory-birds)

Howard Russell:

Howard is a an Entomologist at Michigan State University that specializes in diagnostic services and insect identification. (Source: https://msutoday.msu.edu/for-media/experts/details?u=howard.russell)

To have Howard accurately identify any tick you encounter, e-mail a photo to him at [email protected].

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— David Fair is the WEMU News Director and host of Morning Edition on WEMU.  You can contact David at 734.487.3363, on twitter @DavidFairWEMU, or email him at [email protected]