Montana: Tick-Borne Diseases

Tick-Borne Disease and Daylight Savings Time Arrive Together in Montana, Montana State Department of Public Health and Human Services

Ticks can transmit a variety of infectious organisms to people. During the decade from 1995 to 2005 tick-borne diseases reported in Montana included those caused by bacteria (e.g., Tularemia, Relapsing Fever), rickettsia (e.g., Rocky Mountain Spotted Fever, Q Fever), and viruses (e.g., Colorado Tick Fever). While the symptoms and signs of these diseases vary, an acute febrile illness and history of tick exposure (especially observed ticks or tick bites) often lead to serologically confirmed diagnosis.

No indigenous Lyme Disease, but an unusual (unexplained) syndrome.

Noticeably absent from the list of tick-borne diseases in Montana is Lyme Disease. While there have been several laboratory-confirmed cases of Lyme Disease identified among Montana residents over the years, such cases have invariably had a history of travel to an endemic area prior to their onset of illness. Thus, these cases have been regarded as imported cases, and not reported as Montana cases. Clinicians are urged to be on the lookout for cases among residents at risk due to travel.
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On the other hand in recent years astute Montana clinicians have identified and reported cases with signs and symptoms compatible with Lyme Disease, but which have not lead to serologic confirmation. It is possible that a yet-to-be identified organism is causing a “bulls-eye” rash around the area of a tick bite and the febrile illness that leads patients to seek medical attention in Montana.

Request for reports

We are requesting that physicians and other health care providers report not only serologically confirmed reportable cases of tick-borne disease, but also cases that present with a skin lesion....

Idaho: Tularemia in Livestock in Lincoln County

District Health Issues Alert about Ticks in Rural Lincoln County, South Central District Health

On Wednesday, April 25, South Central District Health was alerted that livestock in rural Lincoln County had contracted a bacterial disease that is often spread by ticks. ...Tularemia, is a potentially serious human and animal illness.... It is caused by the bacterium Francisella tularensis found in animals (especially rodents, rabbits, and hares). The livestock were heavily infested with ticks according to the attending veterinarian.

Oregon: Lyme Disease and Tick Surveillance

Lyme Disease, 2005 State of Oregon Selected Reportable Communicable Disease Summary, Oregon Health Services

In 1997–1998, a tick identification and Borrelia isolation study was conducted by the CDC and the Oregon Department of Human Services in Deschutes, Josephine and Jackson Counties. No ticks from Deschutes County were identified as carrying Borrelia in this study. The organism was isolated in 3% of Ixodes pacificus ticks tested.

During 2005, 24 cases were reported in Oregon.

Arizona: Tularemia 2003-2005

2003-2005 Highlights, Vector-Borne and Zoonotic Disease Newsletter, Arizona Department of Health Services

The state has averaged one case of tularemia per year over the last three years. One case in 2003 is thought to have been acquired from deer fly bites. Cases in 2005 occurred in two Coconino County family members who both had contact with a rabbit carcass. Tularemia, also known as rabbit fever, is a potentially serious bacterial disease most commonly associated with handling rabbits, although bites from infected ticks and deer flies are also known to be a source of infection. Tularemia is part of the reason why we recommend that hunters wear rubber gloves while field-dressing game. Animal surveillance efforts found two tularemia-positive animals in 2005 (a rabbit and a domestic cat, both in Yavapai County). In 2006, a cat with tularemia was reported in the Show Low area.

Arizona: Rocky Mountain Spotted Fever 2003-2005

2003-2005 Highlights, Vector-Borne and Zoonotic Disease Newsletter, Arizona Department of Health Services

Rocky Mountain Spotted Fever (RMSF) has emerged as a major concern in portions of Arizona. Prior to 2004, only eight cases of RMSF had been recorded in the state. In 2004 alone, 15 cases were reported. Another 13 were added in 2005. All of the 2004-2005 cases occurred in mountainous east-central Arizona and appear to be associated with the brown dog tick, Rhipicephalus sanguineus, a species not previously known to be a vector in the U.S. It is thought that the brown dog tick, while not an efficient vector, can transmit RMSF under certain conditions, namely when the number of ticks in a community is large and dogs are allowed to roam freely. Therefore, controlling ticks on dogs and around the home as well as enforcement of animal control regulations are essential steps in preventing RMSF. A very unfortunate aspect of the current outbreak is that it has disproportionately affected children. From 2003-2005, five individuals have died from RMSF infections. RMSF, caused by Rickettsia rickettsii bacteria, is an acute febrile illness typically marked by the sudden onset of moderate to high fever with a rash forming a few days later on the extremities and spreading to the palms and soles and then the torso. Severe headache and muscle aches are also common symptoms. In some cases, infection with R. rickettsii does not produce classic symptoms. Lack of appearance of rash and/or other typical symptoms can delay diagnosis and treatment. A sweeping multi-agency RMSF response effort was undertaken in 2005 and more work is planned for 2006. Because of this recent activity, RMSF should be included in the differential diagnosis for Arizona care providers seeing patients with unexplained rash and fever illnesses. Ticks removed from patients may be submitted to ADHS-Vector for identification.

Rocky Mountain Spotted Fever from an Unexpected Tick Vector in Arizona

Rocky Mountain Spotted Fever from an Unexpected Tick Vector in Arizona, The New England Journal of Medicine

Rocky mountain spotted fever, which is caused by Rickettsia rickettsii, is a life-threatening, tick-borne disease that occurs throughout much of the United States. Case fatality rates can be as high as 20 percent in untreated patients.^1,2 The principal recognized vectors of R. rickettsii are Dermacentor variabilis (the American dog tick) (Figure 1A) in the eastern and central United States and D. andersoni (the Rocky Mountain wood tick) (Figure 1B) in the western United States. Both types of tick feed on small mammals, which may harbor R. rickettsii. D. variabilis, the most common tick associated with Rocky Mountain spotted fever, also commonly feeds on dogs.³ Another common tick throughout the world that feeds on dogs, Rhipicephalus sanguineus (the brown dog tick) (Figure 1C), has not previously been reported to be a natural vector for Rocky Mountain spotted fever in the United States.

Rocky Mountain spotted fever is rarely reported in Arizona, and the expected Dermacentor species vectors are not commonly found in the state.⁴ From 1981 through 2001, only three cases of Rocky Mountain spotted fever were reported for the entire state.^1,2 However, from 2002 through 2004, Rocky Mountain spotted fever was identified in 16 patients from rural eastern Arizona. In this report, we describe that outbreak and summarize the clinical, epidemiologic, and ecologic findings that implicate R. sanguineus as a newly recognized vector for R. rickettsii in the region.

From the National Center for Infectious Diseases, Division of Viral and Rickettsial Diseases and the Epidemic Intelligence Service, Office of Workforce and Career Development, the Centers for Disease Control and Prevention, Atlanta; the Indian Health Service, Whiteriver Service Unit, Whiteriver, Ariz.; and the Indian Health Service, National Epidemiology Program, Albuquerque, N.M.

Tularemia Transmitted By Insect Bites - Wyoming, 2001-2003

Tularemia Transmitted By Insect Bites - Wyoming, 2001-2003, Morbidity and Mortality Weekly Report, Center For Disease Control and Prevention

Tularemia is a zoonotic disease caused by Francisella tularensis, a fastidious, gram-negative coccobacillus that infects vertebrates, especially rabbits and rodents. In humans, tularemia is classified into six major syndromes: ulceroglandular (the most common form), glandular, typhoidal, oculoglandular, oropharyngeal, and pneumonic. The case-fatality rate among humans can reach 30%-60% in untreated typhoidal cases (1). Although bites from ticks and handling infected animals are considered the most common modes of tularemia transmission in the United States (2-4), the disease also is spread through ingestion of contaminated food or water, inhalation, and insect bites (1-5). During 2001-2003, Wyoming experienced an increase in reported human cases of tularemia. This report describes the subsequent investigation by the Wyoming Department of Health (WDH), which indicated that 1) insect bites (particularly from deerflies and other horseflies) were the most commonly reported likely mode of transmission, and 2) the increase in cases was geographically and temporally associated with an outbreak of tularemia among rabbits in southwestern Wyoming. To obtain a timely diagnosis and provide information on appropriate preventive measures, health-care providers and public health officials should have knowledge of the local epidemiology of tularemia, particularly regarding modes of transmission and resultant clinical syndromes.

Tularemia is a reportable disease in Wyoming and is designated as a nationally notifiable disease. In this investigation, a case was defined as a confirmed or probable case of tularemia reported to WDH during 1990-2003. A confirmed case was defined as a clinically compatible case with confirmatory laboratory results, which might include either isolation of F. tularensis in a clinical specimen or a fourfold or greater change in antibody titer. A probable case was defined as a clinically compatible case with laboratory results indicative of infection, which might include either a single elevated antibody titer or detection of F. tularensis in a clinical specimen by immunohistochemistry or immunofluorescence (6). A case of insect-borne tularemia was defined as tularemia that occurred within 14 days of a fly, flea, or other insect bite in a patient with no other known exposures, including tick bites and handling of infected animal tissues. Patient interviews, medical record reviews, or reviews of archived follow-up forms were conducted for each case. In this report, location refers to the geographic location of exposure, except where a definite exposure location was not reported (four cases); in those instances, location refers to place of residence (Table; Figure 1).

During 2001-2003, a total of 11 cases (six confirmed; five probable) of tularemia were reported in Wyoming, for an average of 3.7 cases per year. In contrast, 10 cases (seven confirmed; three probable) were reported during 1990-2000, for an average of 0.9 cases per year (Figure 2).

Of the 11 cases reported during 2001-2003 (Table), nine (82%) were in male patients. Six (55%) of the tularemia cases were the ulceroglandular type, and all included insect bites as the likely mode of transmission. Two cases (18%) were the typhoidal type, and the remaining three cases were the glandular, oculoglandular, and pneumonic types (9% each). No deaths were reported.

In seven (64%) cases, insect bites (from deerflies or other horseflies in six cases; flies and/or fleas in one case) were determined to be the most likely mode of transmission. Six of these patients had ulceroglandular tularemia; one patient had typhoidal tularemia. Median age of persons for whom insect bites were the likely mode of transmission was 40 years (range: 18 months-68 years). Median age of those with other modes of transmission was 53 years (range: 40-70 years). Likely modes of transmission in the other four cases were infected rabbit exposure (one), infected sheep exposure (one), and unknown (two). In contrast, during 1990-2000, no cases were linked to insect bites. The likely modes of transmission in cases during 1990-2000 were ticks (four), rabbits (three), sheep (one), and unknown (two). Eight (73%) of the 11 cases reported during 2001-2003 were reported from counties in southwestern Wyoming (Sweetwater [five], Lincoln [two], and Uinta [one]); the remaining three (27%) were distributed among counties elsewhere in the state (one case each in Fremont, Park, and Teton counties) (Figure 1). The F. tularensis isolates from the six confirmed cases that occurred during 2001-2003 were further classified into types A or B. Five of these typed isolates were from cases in the southwestern region of the state, where an epizootic among rabbits was thought to have occurred; all five were classified as type A. One isolate from the northwestern region was classified as type B.

October 2003, WDH was informed that two ill rabbits from the Seedskadee National Wildlife Refuge in southwestern Wyoming collected in the summer and early fall of 2003 tested positive for tularemia. Refuge personnel reported an increase in the number of dead or ill rabbits during the summers of 2002 and 2003.

Reported by: S Seys, MPH, K Musgrave, DVM, Wyoming Dept of Health. J Cassady, PhD, Drew Univ, Madison, New Jersey. J Hunt, Univ of Utah School of Medicine, Salt Lake City, Utah. T Murphy, MD, EIS Officer, CDC.