Increase in Colorado Tick Fever Virus Disease Cases and Effect of COVID-19 Pandemic on Behaviors and Testing Practices, Montana, 2020.

In 2020, Montana, USA, reported a large increase in Colorado tick fever (CTF) cases. To investigate potential causes of the increase, we conducted a case-control study of Montana residents who tested positive or negative for CTF during 2020, assessed healthcare providers' CTF awareness and testing practices, and reviewed CTF testing methods. Case-patients reported more time recreating outdoors on weekends, and all reported finding a tick on themselves before illness. No consistent changes were identified in provider practices. Previously, only CTF serologic testing was used in Montana. In 2020, because of SARS-CoV-2 testing needs, the state laboratory sent specimens for CTF testing to the Centers for Disease Control and Prevention, where more sensitive molecular methods are used. This change in testing probably increased the number of CTF cases detected. Molecular testing is optimal for CTF diagnosis during acute illness. Tick bite prevention measures should continue to be advised for persons doing outdoor activities.

Colorado Tick Fever Virus in the Far West: Forgotten, but Not Gone.

In the past few decades, reported human cases of Colorado tick fever in the western United States have decreased dramatically. The goal of this study was to conduct surveillance for Colorado tick fever virus (CTFV) in Dermacentor ticks in recreational sites in Colorado, Wyoming, and California to determine whether the virus is still present in Dermacentor ticks from these states. Surveillance focused on regions where surveys had been conducted in the 1950s, 1960s, and 1970s. Adult Rocky Mountain wood ticks (Dermacentor andersoni), Pacific Coast ticks (Dermacentor occidentalis), and winter ticks (Dermacentor albipictus) were tested by PCR. A subset of PCR-positive D. andersoni ticks (n = 7) were cultured in Vero cells. CTFV-positive Rocky Mountain wood ticks were found in all states: Colorado (58% prevalence), Wyoming (21%), and California (4%). Although no winter ticks tested positive, Pacific Coast ticks tested positive in one county (Siskiyou County, 15% prevalence) and were positive only in a location that also maintained Rocky Mountain wood ticks and golden mantled ground squirrels, a known CTFV host. In summary, CTFV is prevalent in D. andersoni and D. occidentalis in regions where they are sympatric in California and in D. andersoni in Colorado and Wyoming. Although the number of human CTFV cases has declined dramatically, this decrease in reported disease does not appear to be due to the disappearance or even the decline in prevalence of this virus in ticks in historically endemic regions of the country.

Laboratory Blood-Based Testing for Non-Lyme Disease Tick-Borne Infections at a National Reference Laboratory.

OBJECTIVES: We evaluated trends in non-Lyme disease tick-borne disease (NLTBI) testing at a national reference laboratory. METHODS: Testing data performed at Quest Diagnostics during 2010 to 2016 were analyzed nationally and at the state level. RESULTS: Testing and positivity for most NLTBIs increased dramatically from 2010 through 2016 based on testing from a large reference laboratory. The number of positive cases, though not as stringent as criteria for public health reporting, generally exceeds that reported by the Centers for Disease Control and Prevention. The frequency of NLTBI in the US is seasonal but testing activity and positive test results are observed throughout all months of the year. Positive results for NLTBI testing mostly originated from a limited number of states, indicating the geographic concentration and distribution of NLTBIs reported in this study. CONCLUSIONS: This report provides an important complementary source of data to best understand trends in and spread of NLTBI.

Tick-Borne Illnesses in the United States.

Close interaction with nature can lead to tick-borne illnesses, which are seen most frequently in primary care clinics when patients present symptoms. Considerable morbidity can result from untreated infections. Fortunately, these illnesses are often easily managed when diagnosed early.

What's eating you? clinical manifestations of Dermacentor tick bites.

Dermacentor ticks are hard ticks found throughout most of North America and are easily identified by their large size, ornate scutum, and prominent dorsal pits. They are important disease vectors and are implicated in transmission of Rocky Mountain spotted fever (RMSF), Colorado tick fever, tularemia, and erlichiosis. They also are an important cause of fatal tick paralysis.

Case Report: A Case of Colorado Tick Fever Acquired in Southwestern Saskatchewan.

Colorado tick fever virus is transmitted by Dermacentor andersoni ticks. In Canada, these ticks are found in the southern regions of British Columbia (Rocky Mountains) and Alberta, as well as southwestern Saskatchewan. Colorado tick fever should be clinically suspected in patients presenting with a biphasic febrile illness and leukopenia following tick exposure in the appropriate geographic area.

The eye and tick-borne disease in the United States.

PURPOSE OF REVIEW: Tick-borne diseases are increasing in incidence and geographic distribution. Several diseases endemic to the United States have ophthalmic manifestations, including the most common tick-borne disease, Lyme borreliosis. As ocular complaints may lead a patient to seek medical evaluation, it is important to be aware of the systemic and ophthalmic manifestations of tick-borne diseases in order to make the correct diagnosis. RECENT FINDINGS: Vision-threatening ophthalmic manifestations are relatively common in Lyme disease and Rocky Mountain spotted fever. Ocular involvement is rare in babesiosis, tick-borne relapsing fever, Powassan encephalitis, ehrlichiosis, anaplasmosis, and Colorado tick fever.There are clear guidelines for diagnosis and treatment of Lyme disease; however, confusion and misinformation among the general public as well as controversy about chronic or late-stage Lyme disease can impact the evaluation of ophthalmic disease. Furthermore, there are many gaps in our knowledge regarding the pathophysiology of ocular borreliosis although it seems likely that Lyme uveitis is rare in the United States. SUMMARY: Knowledge of systemic and ophthalmic manifestations combined with an understanding of the epidemiology of disease vectors is crucial for the diagnosis of tick-borne diseases.

Colorado tick fever in the United States, 2002-2012.

BACKGROUND: Colorado tick fever (CTF) is an acute systemic febrile illness caused by the CTF virus (CTFV). The last national summary of CTF cases in the United States included cases reported through 2001. This study summarizes national surveillance data for CTF from 2002 through 2012 and examines trends in the epidemiology and testing of identified CTF cases. METHODS: Because CTF is not nationally notifiable, we identified CTF cases through solicited reports from state health departments and diagnostic laboratory records. For all cases, we collected data on age, sex, county of residence, travel history, symptom onset date, laboratory testing, and clinical outcome. Poisson regression was used to examine trends over time in case counts, and simple linear regression and logistic regression were used to examine trends in case characteristics. RESULTS: From 2002 through 2012, 75 CTF cases were identified with a median of five cases per year (range 3-14). Forty-seven (63%) cases occurred in males and 49 (65%) occurred in people aged ≥40 years. The majority (80%) of cases had onset of illness during May through July. Cases occurred in residents of 14 states but the infections were acquired in six western states. Wyoming had the highest annual incidence of CTF among residents (3.4 cases per million population), followed by Montana (1.5 per million), and Utah (0.5 per million). Over the 11 years, there was an increase in the proportion of cases diagnosed by RT-PCR testing and in the proportion of cases among travelers to another state. CONCLUSIONS: CTF cases continue to occur annually among residents and visitors to the western United States. Public health prevention messages about decreasing tick exposure should be targeted to residents and travelers who will spend time outdoors in an endemic region during the spring and summer months.

Fiebre recurrente transmitida por garrapatas en área rural del sur de España / Tick-borne relapsing fever in a rural area of southern Spain

INTRODUCCIÓN: La fiebre recurrente transmitida por garrapatas (FRTG) es una enfermedad zoonótica producida por espiroquetas del género Borrelia. Es una enfermedad infradiagnosticada en nuestro medio debido al bajo índice de sospecha y a la dificultad en su diagnóstico. El objetivo del estudio es presentar nuestra experiencia en el manejo diagnóstico y terapéutico de la FRTG y revisar la literatura. MÉTODOS: Análisis retrospectivo de pacientes con FRTG ingresados en nuestro centro durante el periodo 2002-2012. Se analizan variables epidemiológicas, clínicas, microbiológicas, tratamiento y resultado. RESULTADO: Se identificaron 9 pacientes con FRTG. La mediana de edad fue de 11 años. Todos los casos ocurrieron durante meses cálidos. La clínica de presentación fue de episodios recurrentes de fiebre con escalofríos, cefalea, vómitos, mialgias y dolor abdominal. Se identificó afectación meníngea en 2 casos. En 2 pacientes existía infección por Borrelia en otros miembros de la familia en el momento del diagnóstico. La media de PCR fue de 187 mg/l y el 56% de casos presentaron trombocitopenia. Se visualizó Borrelia spp. en frotis de sangre periférica en el 67%. Todos los pacientes recibieron tratamiento antibiótico. Se empleó doxiciclina en mayores de 8 años y eritromicina y penicilina en menores de esta edad. Se produjo reacción de Jarisch- Herxheiner en un paciente. La evolución fue satisfactoria en todos los casos, sin secuelas. CONCLUSIONES: Subrayamos la importancia de mantener un elevado índice de sospecha de FRTG en regiones endémicas. El diagnóstico precoz, junto con el correcto tratamiento, permite evitar la aparición de recurrencias febriles y potenciales complicaciones

INTRODUCTION: Tick-borne relapsing fever (TBRF) is a zoonotic disease caused by spirochetes of the genus Borrelia. This disease is underdiagnosed in our area due to a low index of suspicion among clinicians, as well as its difficult diagnosis. This study aims to present our experience in the diagnosis and therapeutic management of TBRF and a literature review. METHODS: A retrospective medical chart review was carried out on children diagnosed of TBRF from 2002 to 2012 in our hospital, and included clinical, epidemiological, microbiological, treatment, and outcome data. RESULTS: Nine children with TBRF were identified. Median age was 11 years. All cases occurred during warm months. The most frequent presenting clinical findings were fever, chills, headache, vomiting, myalgia and abdominal pain. Meningeal involvement was identified in 2 cases. In the case of 2 patients, Borrelia infection was identified in several relatives at the time of diagnosis. Mean C-protein reactive was 187 mg/L, and low platelet counts were observed in 56% of the cases. Borrelia spp. was visualized in peripheral blood smears in 67% of cases. All of the patients received antibiotic treatment. Doxycycline was used in children older than 8 years and erythromycin and penicillin in the younger ones. Jarisch-Herxheiner reaction occurred in one patient. All cases resolved without sequelae. CONCLUSIONS: We emphasize the importance of maintaining a high level of suspicion in endemic regions of TBRF. Early diagnosis and a correct therapy can prevent the appearance of subsequent fever recurrences and potential complications

Infection with Colorado tick fever virus among humans and ticks in a national park and forest, Wyoming, 2010.

BACKGROUND: Colorado tick fever (CTF) is an underreported tick-borne viral disease occurring in the western United States. CTF illness includes fever, headache, and severe myalgia lasting for weeks. Wyoming has one of the highest CTF incidence rates with approximately 30% of infected persons reporting tick exposure in a Wyoming National Park or Forest before symptom onset. We assessed CTF virus infections among humans and Dermacentor andersoni ticks in Grand Teton National Park (GRTE) and Bridger-Teton National Forest (BTNF). METHODS: In June of 2010, 526 eligible employees were approached to participate in a baseline and 3-month follow-up serosurvey and risk behavior survey. Seropositivity was defined as antibody titers against CTF virus ≥10, as measured by the plaque reduction neutralization test. Ticks were collected at 27 sites within GRTE/BTNF and tested by RT-PCR for the CTF virus. RESULTS: A total of 126 (24%) employees participated in the baseline and follow-up study visits. Three (2%) employees were seropositive for CTF virus infection at baseline. During the study, 47 (37%) participants found unattached ticks on themselves, and 12 (10%) found attached ticks; however, no participants seroconverted against CTF virus. Walking through sagebrush (p=0.04) and spending time at ≥7000 feet elevation (p<0.01) were significantly associated with tick exposure. Ninety-nine percent (174/176) of ticks were D. andersoni, and all were found at ≥7000 feet elevation in sagebrush areas; 37 (21%) ticks tested positive for CTF virus and were found at 10 (38%) of 26 sites sampled. CONCLUSIONS: Although no GRTE or BTNF employees were infected with CTF virus during the study period, high rates of infected ticks were identified in areas with sagebrush at ≥7000 feet. CTF education and personal protection measures against tick exposure should be targeted to visitors and employees traveling to the high-risk environs identified in this study.

Epidemiology of Colorado tick fever in Montana, Utah, and Wyoming, 1995-2003.

Colorado tick fever (CTF) is a biphasic, febrile illness caused by a Coltivirus and transmitted by the Rocky Mountain wood tick, Dermacentor andersoni, in the western United States and Canada. Symptoms generally include acute onset of fever, headache, chills, and myalgias; illness often lasts for 3 weeks or more. Laboratory-confirmed cases of CTF were identified from public health department records in Montana, Utah, and Wyoming, and from the Centers for Disease Control and Prevention diagnostic laboratory records. Additional descriptive epidemiologic data were obtained by medical record abstraction. Ninety-one cases were identified from 1995 to 2003, resulting in an overall annual incidence of 2.7 per 1,000,000 population. The annual incidence decreased over the 9-year study period. Cases were 2.5 times more frequent in males than females. The highest incidence of cases occurred in persons aged 51-70. Tick exposure prior to illness onset was reported in 90% of the cases in which a more detailed history was available. The most common symptoms were fever, headache, and myalgia; 18% of the case patients were hospitalized. While there has been an overall decline in the recognized incidence of CTF cases, the reasons for the decline are unknown. Possibilities include a reduced intensity of surveillance and a true decrease in incidence. As more people continue to visit, move to and work in endemic areas, CTF should be considered in anyone presenting with a febrile illness following tick exposure in an endemic area. Heightened awareness for the disease and tick prevention messages should be part of public health measures to further decrease the incidence of disease.

Powassan encephalitis and Colorado tick fever.

This article discusses two tick-borne illnesses: Powassan encephalitis, a rare cause of central nervous system infection caused by the Powassan virus, and Colorado tick fever, an acute febrile illness caused by the Colorado tick fever virus common to the Rocky Mountain region of North America.

Detection of Colorado Tick Fever viral RNA in acute human serum samples by a quantitative real-time RT-PCR assay.

A quantitative real-time RT-PCR assay for the detection of Colorado Tick Fever (CTF) viral RNA in human clinical samples is presented. The sensitivity of this assay has been shown to be greater than that of the isolation of virus in Vero cells by standard plaque assay in a direct comparison. The specificity of the CTF quantitative real-time RT-PCR assay was determined by the exclusive detection of CTF viral RNAs when applied to a diverse panel of CTF viral isolates and reference strain agents known to circulate in areas of CTF virus transmission. Lastly, the quantitative real-time RT-PCR assay demonstrated exceptional sensitivity for the detection of CTF viral RNA in acute human serum. The quantitative real-time RT-PCR assay is efficient, sensitive and specific and as such is useful for the detection of CTF viral RNA in the diagnostic or research laboratory.

Tick-borne encephalopathies : epidemiology, diagnosis, treatment and prevention.

Tick-borne encephalopathies constitute a broad range of infectious diseases affecting the brain and other parts of the CNS. The causative agents are both viral and bacterial. This review focuses on the current most important tick-borne human diseases: tick-borne encephalitis (TBE; including Powassan encephalitis) and Lyme borreliosis. Rocky Mountain spotted fever (RMSF) and Colorado tick fever (CTF), less common tick-borne diseases associated with encephalopathy, are also discussed. TBE is the most important flaviviral infection of the CNS in Europe and Russia, with 10 000-12 000 people diagnosed annually. The lethality of TBE in Europe is 0.5% and a post-encephalitic syndrome is seen in over 40% of affected patients, often producing a pronounced impairment in quality of life. There is no specific treatment for TBE. Two vaccines are available to prevent infection. Although these have a good protection rate and good efficacy, there are few data on long-term immunity. Lyme borreliosis is the most prevalent tick-borne disease in Europe and North America, with >50 000 cases annually. Localised early disease can be treated with oral phenoxymethylpenicillin (penicillin V), doxycycline or amoxicillin. The later manifestations of meningitis, arthritis or acrodermatitis can be treated with oral doxycycline, oral amoxicillin or intravenous ceftriaxone; intravenous benzylpenicillin (penicillin G) or cefotaxime can be used as alternatives. The current use of vaccines against Lyme borreliosis in North America is under discussion, as the LYMErix vaccine has been withdrawn from the market because of possible adverse effects, for example, arthritis. RMSF and CTF appear only in North America. RMSF is an important rickettsial disease and is effectively treated with doxycycline. There is no treatment or preventative measure available for CTF.

Recombinant VP7-based enzyme-linked immunosorbent assay for detection of immunoglobulin G antibodies to Colorado tick fever virus.

VP6, VP7, VP9, VP10, VP11, and VP12 of Colorado tick fever virus (CTF virus), a virus member of the genus Coltivirus, family Reoviridae, were expressed in bacteria with the pGEX-4T-2 vector. A partial sequence of VP7 (designated pVP7) was chosen to elaborate an enzyme-linked immunosorbent assay (ELISA) for detecting anti-CTF virus immunoglobulin G (IgG) antibodies in humans. This was based on two observations: (i) among all expressed proteins, pVP7 showed the highest immunoreactivity to an anti-CTF virus hyperimmune ascitic fluid; (ii) to provide the highest selectivity of antibody detection, the expressed sequence was chosen within a region which is highly divergent (49% amino acid identity) from the homologous sequence of another coltivirus, the Eyach virus. The pVP7 ELISA was evaluated with 368 serum samples from French blood donors and found to provide 98.1% specificity. Assays with the Calisher set of human serum samples, positive for anti-CTF virus antibodies (C. H. Calisher, J. D. Poland, S. B. Calisher, and L. A Warmoth, J. Clin. Microbiol. 22:84-88, 1985), showed that the pVP7 ELISA provided 100% sensitivity for the tested population. After elaboration of recombinant-protein-based ELISAs for diagnosis of infections with members of the viral genera Orbivirus, Orthoreovirus, and Rotavirus, it was shown that a recombinant protein could be used to detect antibodies to the human pathogen Colorado tick fever virus.

[Neurologic problems in tick-borne diseases--clinical and diagnostic aspects]. / Problemy neurologiczne w chorobach przenoszonych przez kleszcze--aspekty kliniczne i diagnostyczne.

Tick carried illnesses frequently lead towards neurological complications. The tick-borne encephalitis and borreliosis are the most frequently encountered illnesses having such aetiopathogenesis. In the study there are presented clinical aspects of tick-borne encephalitis and borreliosis with special consideration of various neurological symptomatology. Simultaneously there are discussed current diagnostic rules of the diseases, mainly on the basis of serologic investigation.

Colorado tick fever.

Colorado tick fever, also known as mountain fever and mountain tick fever, is a well-described, viral, tick-borne disease common to the Rocky Mountain region of the United States and Canada. The Rocky Mountain wood tick, Dermacentor andersoni, is the primary vector. The triad of high fever, severe myalgia, and headache is typical, but not specific. Although a self-limited disease in most cases, severe complications may occur. PCR techniques have been developed that allow the diagnosis to be established from the first day of symptoms. Ribavirin may merit consideration in the appropriate clinical setting.

Gastrointestinal and hepatic manifestations of tickborne diseases in the United States.

Signs and symptoms related to the gastrointestinal tract and liver may provide important clues for the diagnosis of various tickborne diseases prevalent in different geographic areas of the United States. We review clinical and laboratory features that may be helpful in detecting a tickborne infection. Physicians evaluating patients who live in or travel to areas where tickborne diseases are endemic and who present with an acute febrile illness and gastrointestinal manifestations should maintain a high index of suspicion for one of these disease entities, particularly if the patient has received a tick bite. If detected early, many of these potentially serious illnesses can be easily and effectively treated, thereby avoiding serious morbidity and even death.