TICK-BORNE DISEASES IN MONTANA

 

OVERVIEW

When it's springtime in the Rockies, that is also the time to watch out for ticks and the diseases they carry.In Montana, ticks are known to be disease carriers for: Rocky Mountain Spotted Fever, Colorado Tick Fever, Tularemia (commonly known as "rabbit fever")

NOTE: The types of ticks in Montana have not been shown to transmit Lyme Disease according to Todd Damrow, Ph.D., state epidemiologist.

 

GENERAL CHARACTERISTICS:

Ticks like to crawl up on low vegetation and wait for people or animals to brush up against them. Ticks become aroused by the odor and breathing of any nearby host and transfer to humans or animals by stretching their legs toward the host. Ticks do not fly or jump but crawl slowly. Ticks seldom attach to hosts for several hours after contact.The tick season in Montana lasts from the onset of warmer weather in the spring until about mid-July when warmer weather and low relative humidity cause the ticks to become inactive.

 

WHERE FOUND:

Areas most likely to be infested with ticks are wooded and mountainous regions particularly where wild rodents and domestic animals share territories.

 

TIPS FOR REDUCING TICK-BORNE DISEASE

Avoid high-risk areas that are brushy and densely wooded from spring until mid-July. Wear light-colored clothing that fits tightly at ankles, waist and wrists. (Ticks are easier to spot on light colors.) Long sleeves and pants are recommended. Examine yourself and your children every few hours for ticks, especially in areas that ticks find inviting: hairline, ears, underarms, body folds, hairy regions of the body and inside clothing.

 

In highly infected areas during peak exposure times of the year, protection may be increased by using an insect repellent on your skin and clothes containing N-N-diethyl-meta-toluamide, product names DEET. Other protective non-chemical measures are preferred. Check pets frequently during tick season, especially around the face and ears. If pets are allowed into the home after being outside, a quick inspection for ticks and brushing are helpful. Shampoos, sprays and dusts are available to eliminate ticks on pets. Tick collars may repel ticks but are less effective.

 

IF YOU FIND A TICK ON A PERSON OR ANIMAL

 

Preferably, use forceps or tweezers to remove ticks. Carefully grasp the mouth parts (the point of attachment) and pull gently but firmly upward. DO NOT jerk or twist the tick loose as this might cause the mouth parts to remain embedded in the skin. If tweezers are not available, protect fingers with plastic gloves or at least tissue paper. Apply an antiseptic to the bite wound and wash hands thoroughly with soap and water.

 

As a precaution, place the tick in a small covered container or pill bottle. Record the date of tick exposure and removal on paper and place in container. Report any symptoms of general malaise (weakness), headache and/or muscle pain within two weeks of the removal to a health professional.

 

TICK-BORNE DISEASES IN MONTANA

 

Rocky Mountain Spotted Fever:

Organism: Rickettsia rickettsii - 1% to 3% of ticks are infected by this micro organism.

Incubation Period: From 3 days to about 14 days

Symptoms: Sudden onset with moderate to high fever. Untreated, fever may persist for 2 - 3 weeks. Significant malais, Deep muscle pain, Severe headache, Chills,

Conjunctival injection

A rash appears on the extremities from the second to the sixth day of fever and characteristically shows up on palms, soles, ankles and/or forearms. Contracted primarily by adults in the Rocky Mountain region.

Infectious agent: Ticks. The rickettsiae can be transmitted to dogs, rodents and other animals.

Mode of transmission: Usually through the bite of an infected tick, most often the wood tick, D. andersoni

Treatment: Tetracyclines or chloramphenical

1994 Cases in Montana: 4 cases, no deaths

 

Colorado Tick Fever

Organism: A virus

Incubation period: Usually 4 - 5 days

Symptoms: Chills, Headache, Fever - usually ranging from 102 to 104 for two to three days which is often followed by a second bout of fever, Muscle aches, Rash (infrequent)

In children - rarely severe

In older adults - recovery may take months

Infectious agent: Small mammals, ground squirrels, porcupine, chipmunks, and Peromyscus spp.

Mode of transmission: Tick: Primarily the wood tick (D. andersoni) that feeds on infected animals.

Treatment: No specific treatment

1994 Cases in Montana: 6 cases, no deaths

 

Tularemia (rabbit fever, deerfly fever)

Organism: Zoonotic, bacterial - Francisella tularensis

Incubation period: 2 - 10 days, usually 3 days

Symptoms: Depends upon route of introduction to the body and the virulence of the strain. Characteristically, an ulcer (sore) forms at the site of the tick bite which is frequently on the hand. Ulcer often becomes tissue-destroying. Swelling and tenderness of lymph nodes. Inhalation of infected material may cause pulmonary disease or typhoidal syndrome.

Infectious agent: Wild animals, especially rabbits, hares, muskrats and some domestic animals. Ticks, primarily the wood tick (D. Andersoni).

Mode of Transmission: Injection into skin, conjuctival sac or oral cavity with blood or tissue while handling infected animals, as when skinning or dressing. Bite of wood ticks, D. andersoni.

Treatment: Usually streptomycin or gentamycin

Other: Tetracyclines

1994 Cases in Montana: 3 cases, no deaths

 

INFORMATION SOURCES:

Bartlett, John G. Pocket Book of Infectious Disease Therapy, Williams & Wilkins, 1994.

Benenson, Abram S., editor. Control of Communicable Diseases in Man. American Public Health Association, 1990.

Burgdorfer, Willy. "The Rocky Mountain Wood Tick: Beware Its Bite." Information sheet produced for Montana Fish, Wildlife and Parks.

Jacobs, Steven. Ag Information Services - News & Publications, Pen State College of Agricultural Sciences, Document Number: 283012554.

Montana Department of Health and Environmental Sciences. Press release, April 18, 1995. For more information: Todd Damrow - (406) 444-3986.

Reviewed by Todd Damrow, Ph.D., Epidemiologist at the Montana Department of Health and Environmental Sciences.

Date: 12/03/2001

Categories: Ticks, Bites, Disease