By AA Kiessling, PhD
Approximately two hundred people attended talks by three tick experts in the Lincoln Schools auditorium April 30. The event was organized by the Middlesex Tick Task Force, a group of public health staff members and residents from Acton, Bedford, Carlisle, Concord, Lexington, Lincoln, Waltham, Wayland and Weston formed in September, 2012, to confront the serious public health issue posed by tick-borne diseases.
A new tick testing program (https://www.tickdiseases.org/medical-zoology/cic/) through the Tick-Borne Disease Network of 32 Massachusetts towns, headed up by the Bedford Board of Health, was also described by Dr. Stephen Rich.
Dr. Alfred DeMaria
Massachusetts Department of Public Health Epidemiologist
Dr. De Maria outlined the life cycle of Ixodes scapularis, the deer tick that carries Lyme disease (Borrelia burgdorferi), and reminded the audience that Lyme disease is so-named for Lyme, CT, where it was identified approximately 40 years ago as the causative agent for an outbreak of juvenile rheumatoid arthritis. The highest incidence of infection in Massachusetts is during June and July affecting mostly children and adults over 40 years old. The increase in the deer population, secondary to the reversion of farm land to forests in Massachusetts, has led to the marked increase in Lyme disease in the past few years. Deer are the unaffected hosts for the adult tick, I. scapularis, that carries Lyme disease, and although adult ticks can transmit B. burgdorferi to humans, it is thought to be the nymph form of I. scapularis which feeds on infected field mice that in turn transmits most human disease. The deer blood meal supports the laying of millions of fertilized eggs by the adult I. scapularis, that winter-over, becoming larvae the following spring, which again winter over, becoming nymphs the following spring. The nymphs feed on infected field mice and humans, if possible.
In addition to Lyme disease, Dr. DeMaria reported that B burgdorferi infection can also cause Bell’s palsy, and inflammation of the heart (myocarditis). When asked about a human vaccine for Lyme disease, Dr. DeMaria reported that the vaccine that had been developed was novel in that it actually killed the organism within the tick. It was taken off the market because the manufacturing company was losing money on the vaccine. Because it remains an approved treatment, it is possible that another company could pick up the license and produce the vaccine.
Dr. DeMaria pointed out that I. scapularis also transmits Babesiosis (“Nantucket Fever”), an infection of red blood cells by a tiny parasite, Babesia microti. Because it may not cause any symptoms, infection may go unnoticed, and it has become the Number One blood transfusion transmitted disease in the U. S. today.
According to Dr. DeMaria, the incidence of Babesiosis has doubled since 2012, and it may soon exceed the numbers of new cases of Lyme disease each year.
Dr. Stephen Rich
University of Massachusetts Laboratory of Medical Zoology, and a member of a global network of epidemiologists studying tick-borne diseases
Dr. Rich described the new Tick-Borne Disease Network (TBDN) in Massachusetts. The goal is to analyze 50 spring ticks and 50 fall ticks submitted from each of 32 Massachusetts towns that have signed up for the program (https://www.tickdiseases.org/medical-zoology/cic/). The Bedford Board of Health will administer the $110,000 from the Governor’s Community Innovation Challenge Grant program. According to Dr. Rich, this is the first time the state has funded this type of tick research, in contrast to the approximately $9 million the state allocates each year for mosquito surveillance.
Dr. Rich’s laboratory began testing ticks in 2006 for 3 pathogens: B burgdorferi, B microti, and Anaplasma phagocytophilum. The testing has been funded by fee-for-service until this year, when the Governor’s Challenge Grant was funded, allowing the testing of approximately 3200 ticks from the 32 participating towns. Dr. Rich stressed that having a tick test positive for one or more of the 3 pathogens does NOT mean the person or animal from which the tick was removed actually has the corresponding disease. Dr. Rich emphasized that it is possible to remove a tick attached to your skin, have that tick test positive for B. burgdorferi in his lab, but you may still not be infected with B. burgdorferi yourself because it takes many hours of being attached to your warm skin for the B. burgdorferi to multiply to sufficient levels to be transmitted. This is an important point.
The goal of testing ticks is not to diagnose disease in the tick’s most recent host, but to gain epidemiologic data, including where the tick came from, what blood the tick had fed on, how many diseases it contains, etc. A diagnosis of infection comes from symptoms.
The information will, nonetheless, present a conundrum for health care providers. The report from Israel on transmission of B. burgdorferi without and with a few doses of doxycycline administered within a few days of tick exposure has provided the basis for the current treatment recommendation: one or two doses of doxycycline if the discovered tick has been attached more than two days; a few hours of attachment was not found to be sufficient to transmit disease. With the current concern about the over-use of antibiotics, most health care providers are reluctant to prescribe doxycycline in the absence of the characteristic rash (“erythema migrans”) or other symptoms.
On the other hand, untreated Lyme disease occasionally becomes a life-long debilitating syndrome, which seems more serious than the potential antibiotic resistance created by a few doses of doxycycline.
These considerations highlight the obvious importance of minimizing the risk of tick-borne diseases, through protective measures, and by more accurate epidemiology through tick testing. Massachusetts appointed a Special Commission to study Lyme Disease in Massachusetts, their comprehensive report was published in 2013: https://malegislature.gov/Content/Documents/Committees/H46/LymeDiseaseCommissionFinalReport-2013-02-28.pdf.
President of ohDeer, Inc
Mr. Upham presented several landscaping ideas to limit tick exposure to friends and family while in the backyard (https://www.ohdeer1.com). He stressed the importance of removing leaf litter, known to harbor I. scapularis because it requires humidity of greater than 85% to survive, conditions provided by piles of leaves, unmowed grass, sometimes tree shade. Mr. Upham stressed the value of creating a boundary — gravel, bark mulch — between family activity areas and forested leaf litter areas. He distributed samples of Damminix Tick Tubes (https://www.ticktubes.com) which contain mouse nesting materials penetrated with permethrin, the synthetic form of the chrysanthemum pesticide. The tubes are designed to be placed at strategic areas in the yard for mice to discover and carry back the treated nesting materials (cotton balls) to their nests, thus killing the ticks brought there and potentially greatly reducing the tick population available to feed on deer and people. Mr. Upham also stressed the importance of a nightly “tick check” of all body parts, after spending time in forested or grassy areas.
All the tick experts agreed:
- Deer populations need to be controlled
- Tick control on mouse populations needs to be included
- The incidence of tick-borne diseases is higher in the northeast than other regions of the country, and Bedford could be in a hot spot at estimates of 300 to 500 cases per 100,000 population, according to the Massachusetts Special Commission report.
- The use of DEET (a deterrent, but not a pesticide) and pymethrin (a pesticide) on clothing and in mouse nests, vigilance after exploring leafy forests and grassy meadows, and consultation with your health care provider after tick removal are all personal protective measures that will diminish the risks of acquiring a tick borne disease.