01Approach to the Critical Patient/attcp50

Immediate priorities

›Airway and mental status threats

›Meningoencephalitis concern

›Altered mental status

›Seizures

›Nuchal rigidity

›If GCS < 13, immediate CT head then lumbar puncture

›Neurology or critical care consult

›Empiric coverage for bacterial meningitis until ruled out

›Hemorrhagic manifestations

›Petechiae or purpura

›Active bleeding

›Circulation and sepsis threats

›Shock physiology uncommon but possible in severe cases

›SBP < 90 mmHg

›MAP < 65 mmHg

›DIC concern in severe pediatric cases

›Petechiae and bleeding

›Thrombocytopenia on CBC

›If septic shock physiology, consider bacterial co-infection or RMSF

›Empiric doxycycline within 1 hour if RMSF cannot be excluded

›Class I recommendation for empiric doxycycline in suspected RMSF

Cannot-miss diagnosis

›Rocky Mountain spotted fever must be excluded

›Same tick vector (Dermacentor andersoni)

›Similar early presentation of fever, headache, myalgia

›RMSF rash typically appears day 3 to 5 on wrists and ankles

›Centripetal spread to trunk

02History/hx75

Presentation pattern

›Classic syndrome

›Abrupt onset fever

›Often 39 to 40 C

›Chills and rigors

›Severe headache

›Photophobia common

›Retrobulbar pain described

›Myalgias

›Diffuse and severe

›Lower extremity predominance

›Fatigue and malaise

›Lethargy prominent

›Weakness persisting weeks after resolution

›Biphasic fever pattern

›Saddleback fever in approximately 50% of patients

›Initial febrile phase 2 to 4 days

›Apparent remission 1 to 3 days

›Second febrile phase 2 to 4 days

›Prolonged convalescence

›Weakness and fatigue lasting 3 or more weeks in approximately 50%

›More prolonged in older adults

Tick exposure history

›Tick exposure

›Recent outdoor activity in endemic mountainous western US

›Colorado, Utah, Montana, Wyoming, Idaho, Oregon

›Elevation typically 4,000 to 10,000 feet

›Activities in tick habitat

03Physical Exam/exam59

Vitals and general

›Stability assessment

›Temperature

›Fever often greater than 39 C

›Hypothermia uncommon but marker of severe illness

›Heart rate

›Tachycardia common with fever

›Dehydration contribution

›Blood pressure

›Hypotension rare in uncomplicated CTF

›SBP less than 90 mmHg prompts RMSF and sepsis evaluation

›Oxygen saturation

›Usually normal

›Desaturation prompts complication evaluation

›General appearance

›Ill-appearing with lethargy

›Degree of distress

›Ability to provide history

Skin and lymph nodes

›Skin examination

›Full skin survey for attached ticks

›Hair, axillae, groin, behind ears

›Tick removal if found

›Rash

›Maculopapular or petechial rash in fewer than 20%

›Petechial rash raises concern for RMSF or meningococcemia

›Eschar

›Absence helps distinguish from some other tick-borne illnesses

04Differential Diagnosis/ddx53

Life threats

›Rocky Mountain spotted fever

›ICD-10 A77.0

›Same tick vector and geography

›Early presentation identical to CTF

›Characteristic rash wrists and ankles spreading centripetally day 3 to 5

›Rapidly fatal without doxycycline treatment

›Cannot be excluded clinically early — empiric doxycycline required if suspected

›Meningococcemia

›ICD-10 A39.4

›Petechial or purpuric rash

›Meningeal signs

›Rapid deterioration

Tick-borne co-infections and mimics

›Ehrlichiosis and anaplasmosis

›ICD-10 A77.4 and A79.82

›Fever, headache, myalgias

›Leukopenia and thrombocytopenia overlap with CTF

›Morulae on peripheral smear distinguishes

›Tick-borne relapsing fever

›Biphasic or relapsing fever pattern similar to CTF

›Spirochetes visible on peripheral blood smear

›Borrelia species

›Lyme disease

›ICD-10 A69.2

›Erythema migrans rash in 70 to 80%

›Different tick vector Ixodes species

›Different geographic distribution eastern and upper midwest US

05Laboratory Tests/lt50

Core labs

›Complete blood count

›Leukopenia characteristic of CTF

›White cell count typically 2.0 to 4.0 x10^9/L

›Lymphopenia common

›Thrombocytopenia

›Moderate reduction typical

›Platelet count below 150 x10^9/L common

›Anemia uncommon unless prolonged illness

›Comprehensive metabolic panel

›Generally unremarkable in uncomplicated CTF

›Mild transaminase elevation possible

›ALT and AST

›Not usually severe

›Electrolytes for dehydration assessment

›Sodium trend

›Renal function baseline

Confirmatory and specialized testing

›RT-PCR for CTF virus RNA

›Preferred acute diagnostic test

›Detects viral RNA from day 1 of symptoms through first 2 weeks

›High sensitivity in early illness phase

›Sample type

›Whole blood preferred

›Available at some commercial labs, state health departments, and CDC

›Sensitivity highest in first week of illness

›Serology

›Antibody production delayed 14 to 21 days after symptom onset

06Diagnostic Tests/dt58

Scoring Systems

›No validated clinical scoring systems specific to CTF

›Clinical diagnosis relies on epidemiologic and clinical criteria

›Tick exposure in endemic western US mountainous region

›Appropriate season April through July

›Classic biphasic fever with leukopenia and thrombocytopenia

›Clinical probability framework

›Definite CTF: laboratory confirmed by RT-PCR or serology

›Probable CTF: clinical syndrome with epidemiologic link without confirmatory testing

›Risk stratification approach

›Severity markers warranting admission

›Neurologic involvement

›Hemorrhagic manifestations

›DIC

›Severe dehydration

›Features favoring safe discharge

›Alert and oriented

›Tolerating oral fluids

›Reliable follow-up available

›Fever without complications

MRI

›MRI brain indications in CTF

›Meningoencephalitis evaluation

›Altered mental status not explained by fever alone

›Focal neurologic deficits

›Seizures with neurologic concern

›MRI findings in CTF meningoencephalitis

›May show T2 signal abnormalities in white matter

07Disposition/dispo40

Admission indications

›Hospital admission criteria

›Neurologic involvement

›Altered mental status

›Seizures

›Meningeal signs

›Hemorrhagic manifestations

›Petechiae

›Active bleeding

›DIC concern

›Severe dehydration

›Inability to tolerate oral fluids

›Persistent vomiting

›Cannot exclude RMSF or other serious tick-borne illness

›Empiric doxycycline required while awaiting testing

›Significant comorbidities

›Immunocompromised state

›High risk for complications

ICU indications

›Critical illness triggers

›Meningoencephalitis with GCS less than 13

›Intracranial pressure monitoring consideration

›Neurology and critical care consult

›DIC with active bleeding

›Blood product replacement

›Hematology consult

›Septic shock physiology

›Vasopressor requirement

08Treatment/t55

Supportive care

›Symptomatic management

›Antipyretics and analgesics

›Acetaminophen 650 to 1000 mg PO every 6 to 8 hours in adults

›Maximum 4 g per day in adults without liver disease

›Preferred agent for fever and myalgia

›Ibuprofen 400 to 600 mg PO every 6 to 8 hours in adults

›Avoid in dehydration or renal compromise

›Avoid in children with viral illness if salicylate use is also a risk

›Avoid aspirin in children

›Risk of Reye syndrome with viral illness

›Acetaminophen preferred in pediatric patients

›Hydration

›Oral rehydration encouraged

›Small frequent sips if nausea present

›Target urine output greater than 0.5 mL/kg/hour

›IV hydration when oral intake insufficient

›Normal saline 500 mL to 1 L IV bolus for moderate dehydration

›Reassess volume status after each bolus

Empiric antibiotic therapy

›Doxycycline when RMSF cannot be excluded

›Adult dosing

›Doxycycline 100 mg PO or IV every 12 hours

›Continue until RMSF excluded or minimum 3 days afebrile

›Pediatric dosing

›Doxycycline 2.2 mg/kg PO or IV every 12 hours for children under 45 kg

›Maximum 100 mg per dose

›Safe in children for short courses despite age below 8 years per CDC guidance

09Special Populations/sp54

Pregnancy

›Pregnancy considerations

›CTF in pregnancy risk profile

›Rare documented cases

›Potential for fetal infection via transplacental transmission

›Spontaneous abortion and intrauterine fetal demise reported

›Fever management in pregnancy

›Acetaminophen preferred for antipyresis

›650 to 1000 mg PO every 6 to 8 hours

›Avoid NSAIDs especially in third trimester

›Aggressive fever control to reduce teratogenic risk

›Diagnostic considerations

›RT-PCR preferred for diagnosis

›Fetal monitoring when fever present

›Obstetrics consult for pregnant patients

›Antibiotic considerations if RMSF cannot be excluded

›Doxycycline risk-benefit discussion

›RMSF is rapidly fatal and outweighs doxycycline risks

›Discuss with obstetrics and infectious disease

Geriatric

›Older adult features

›More severe and prolonged illness

›Prolonged convalescence greater than 3 weeks common

›Weakness and fatigue prominent

›Atypical presentation risk

›Delirium as primary presentation

›Afebrile infection possible despite serious illness

›Baseline cognitive status clarification important

10Background/b67

Epidemiology

›Incidence and distribution

›Reported cases typically 200 to 400 per year in US

›Likely underreported due to mild illness and limited testing

›Reportable disease in most endemic states

›Geographic distribution

›Rocky Mountain region and western US

›Colorado, Utah, Montana, Wyoming, Idaho, Oregon

›Southwestern Canada at lower frequency

›Seasonal distribution

›98% of cases April through July

›Peak late May to early July

›Concordance with D. andersoni adult activity

›Demographics

›Male sex predominance

›65% of cases

›2.5 to 1 male to female ratio

›Median age 55 years

›Highest incidence ages 51 to 70

›Children account for minority but have highest complication risk

›Tick infection prevalence

›D. andersoni tick infection rate ranges from 3% to 58%

›Geographic variation within endemic range

Pathophysiology

›Viral biology

›CTF virus (Coltivirus genus, Reoviridae family)

›Double-stranded RNA virus

›12-segmented genome

11Patient Discharge Instructions/pdi38

copy discharge instructions

›Colorado Tick Fever home care

›Rest and increase fluid intake

›Water, electrolyte drinks, broth

›Aim for clear to pale yellow urine

›Fever and pain management

›Acetaminophen as directed for fever and muscle aches

›Do not give aspirin to children

›Return if fever not improving after several days

›Expect a second wave of symptoms

›Fever may go away for 1 to 3 days then return

›This saddleback pattern is typical of Colorado Tick Fever

›Persistent worsening or new severe symptoms require re-evaluation

›Activity

›Rest during febrile phase

›Gradual return to activity as tolerated

›Prolonged fatigue and weakness may last several weeks

›Blood donation restriction

›No blood donation for at least 6 months after illness

›Virus can persist in red blood cells

›Inform any future blood donation center of recent CTF

›Tick prevention

›Use insect repellent with DEET or picaridin in endemic areas

›Wear long sleeves and tuck pants into socks in tick habitat

›Perform tick checks after outdoor activities

›Remove attached ticks promptly with fine-tipped tweezers

›Return to ER immediately for

›Confusion or difficulty waking up

12References/r22

Guidelines and key sources

›Guideline and authoritative sources

›CDC Division of Vector-Borne Diseases: Colorado Tick Fever guidance

›Diagnostic testing algorithms and RT-PCR protocols

›Epidemiologic case definitions

›ACEP Clinical Policy on evaluation and management of tick-borne illness

›Infectious Diseases Society of America (IDSA) tick-borne illness guidance

›Key evidence sources

›Epidemiologic studies

›Male predominance 65% and median age 55 years data

›Seasonal distribution 98% of cases April through July

›Male to female ratio 2.5 to 1

›Clinical natural history data

›Biphasic fever pattern in approximately 50%

›Prolonged convalescence greater than 3 weeks in approximately 50%

›Only 52% of patients recall tick bite despite 90% reporting tick exposure

›Diagnostic test performance

›RT-PCR sensitivity highest in first 2 weeks of illness

›Serology delayed 14 to 21 days requiring convalescent specimens

›Coding standards

›ICD-10 A93.2 Colorado tick fever

›SNOMED CT Colorado tick fever disorder

›Rocky Mountain spotted fever ICD-10 A77.0 for differential coding

Evidence & Review

Evidence & Review