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.

Mysterious Tick-Borne Disease, Montana

Sleuthing Mysterious Tick-Borne Disease A Chilling Endeavor, Montana State Department of Public Health and Human Services

Damrow is the Montana state epidemiologist, and--along with his colleagues at the Montana Department of Public Health and Human Services, the U.S. Centers for Disease Control and Prevention, and the NIH, Rocky Mountain Laboratories--he has spent the past few years investigating reports of a tickborne rash similar to that found in Lyme disease.

Damrow first thought something strange was going on a few years ago, when he began getting reports from patients and physicians of what appeared to be Lyme disease. The patients complained of fever and severe fatigue, as well as odd circular rashes at the site of a previous tick bite. The symptoms were similar to those of Lyme disease....

Then one spring, a public health worker mailed Damrow a photo of the distinctive rash. It was unlike anything he had seen before, and it prompted him to launch a more formal investigation. He knew the Centers for Disease Control and Prevention (CDC) were looking into Lyme-like symptoms caused by unidentified infectious agents in Lone Star ticks in Texas and dog ticks in Missouri. Could the same thing be happening with wood ticks in Montana?

The only way to solve the mystery was to collect the offending ticks, extract DNA from their salivary glands, and study it with molecular probes to find out whether some new bacterium or other pathogen had infected the ticks.

“So last spring we launched a ‘save the tick’ campaign,” Damrow said.

Through news releases and public service announcements on radio and TV, the state Department of Public Health and Human Services (DPHHS) asked Montanans who found ticks embedded in their skin to carefully remove the tick, drop it alive into a plastic bag, and take it immediately to their county health department.

DPHHS staff also notified physicians and county health workers about the study, and they became integral partners in the research effort. They collected the ticks, documented patients’ symptoms, and mailed the ticks to DPHHS.

Damrow was hoping to collect around 100 tick samples.

“We thought it would be pretty hard to get people to hang onto ticks after removing them,” he said. “Usually you just want to throw the nasty little buggers in the trash.”

But the public information campaign was more effective than he had dared to hope. He soon had a collection of about 350 ticks, “and that was after excluding the ones that didn’t actually bite someone.”

His colleague, CDC epidemiologist Kammy Johnson, plans to start tracking bite victims to find out whether the mysterious disease has any late-developing or long-term effects.

DPHHS enlisted researchers at the NIH, Rocky Mountain Laboratories in Hamilton to search for antibodies in the blood of bite victims that might help to identify the pathogen and confirm its role in the disease. The partnership with the labs seemed especially appropriate, Damrow noted, since they were the first to identify Rocky Mountain spotted fever almost a century ago. And in 1982, a scientist at the lab identified the causative agent in Lyme disease.

For the second year in a row, the Montana Dept. of Public Health and Human Services is asking Montanans to help with researching a potentially new disease transmitted by ticks.

Anyone who finds a tick embedded in his or her skin is asked to remove it carefully, drop it alive into a plastic bag, and promptly take it to the county health department. County health workers will collect information about the geographic location where the tick was picked up, the location of the tick bite, and the date the tick was removed.

If an individual develops a rash at the site of a tick bite within 7 to 21 days after removing the tick, he or she is encouraged to visit a health-care provider. A doctor or nurse will collect a blood sample, which will be examined for signs of a germ that may have caused the rash. The identities of those who participate in this study will be kept confidential as required by law.

For more information, call your county health department.

Montana: Tick-Borne Relapsing Fever Caused by Borrelia hermsii

Tick-Borne Relapsing Fever Caused by Borrelia hermsii, Montana, Emerging Infectious Diseases, Centers for Disease Control and Prevention

Five persons contracted tick-borne relapsing fever after staying in a cabin in western Montana. Borrelia hermsii was isolated from the blood of two patients, and Ornithodoros hermsi ticks were collected from the cabin, the first demonstration of this bacterium and tick in Montana. Relapsing fever should be considered when patients who reside or have vacationed in western Montana exhibit a recurring febrile illness.

This tick has been found in southern British Columbia, Washington, Idaho, Oregon, California, Nevada, Colorado, and the northern regions of Arizona and New Mexico.