Vector-Borne & Zoonotic Disease Test 1 Flashcards
Ticks in the US
Black Legged (I.scapularis) - Lyme, Babesiosis (Nymph stage), Ehrlichiosis, Anaplasmosis
Lone Star Ticks (Amblyomma americanum) - Anaplasmosis, Tularemia, Souther tick-associated rash illness, Ehrlichiosis
American dog tick (Dermacentor variabils) - Rocky Mountain Spotted Fever, Tularemia
Lyme Disease
Tick Based - Bacterial Spirochete - (forested regions Primarily Borrelia Burgdorferi, NE US) I.scapularis NE, I.pacificus West Coast - Bimodal peaks 5-14 Y/O and 45-55 Y/O - Commonly contracted between June-Aug
Europe - Austria, Estonia, Lithuania, Netherlands, Slovenia - I.Ricinus, Asia - Russia, Japan, China - I.persulcatus
Transmission = Larva (rarely infected), Nymphal (25%), Adult (50%) must be attached 36-48 hours.
Clin Man = 3 Stages - Early Localized, Early Disseminated, Late Lyme
Lyme Disease: Early Localized Disease - Clinical Manifestation
Only ~25% recall Tick bite
Erythema migrans (EM) - 79% of PTs - Presents within 7-14 days, but can present up to 30 days after.
Associated Viral Syndrom - Fatigue (79%), Anorexia (26%), Mild Headache (42%), Mild Neck Stiffness (44%), Myalgias and Arthralgias (44%), Regional Lymphadenopathy (23%), Fever (16%)
Lyme Disease: Early Disseminated Disease - Clinical Manifestation
Usually present weeks-months after bite
Neurologic symptoms - Cranial nerve Palsies - especially facial nerve (Bells Palsy), Lymphocytic meningitis, Radiculopathy, Peripheral Neuropathy, Mononeuropathy, Cerebellar Ataxia, Encephalomyelitis
Neurological Lyme disease (Triad) - Cranial Neuropathy, Meningitis, Radiculoneurapathy
Carditis - AV Heart block, Pericarditis, Sudden Cardiac Death, Chronic Cardiomyopathy, Palpitations
Ocular Manifestation - Conjunctivitis (10%), Keratitis, Iridocyclitis, Retinal Vasculitis, Choroiditis, Optic Neuropathy, Uveitis
Lyme Disease: Late LymeDisease - Clinical Manifestation
Occurs Months to years after onset of infection
Arthritis - Intermittent or persistent arthritis in a few large joints, especially the knee
Neurologic features - Lyme encephalopathy: Subtle cognitive disturbances, Polyneuropathy
Fibromyalgia
Lyme Disease: Post Lyme Disease Syndrome- Clinical Manifestation
Used to describe the non-specific symptoms that may persist for a months after Tx of Lyme disease.
Headache, Fatigue, Arthralgia, Cognitive difficulties, Musculoskeletal pain
For the majority of PTs these symptoms improve gradually over 6-12 months.
Lyme Disease Diagnostic Studies
Labs - CBC - Leukocytosis (5%), Leukopenia (4%), Anemia (3%), Thrombocytopenia (1.5%), Elevated ESR (24%), Elevated Creatine Phosphokinase (CPK) (12%), LFT - Elevated AST & ALT (37%)
Spirochetemia on blood culture - usually not preformed
Lyme Serologic Testing - ELISA testing (Most common initially) - IgM (early), IgG (late), and combined IgM/IgG. - THis or Immunoflourescense Assay (IFA) completed if Positive or equivocal -> IgM and IgG Western Blot (if Si/Sx <or>or= 30 days)</or>
Test if Recent travel to Endemic area/ Risk factor for exposure and symptoms consitant w/ Lyme
Lyme Disease Treatment
First-line - Doxycycline
Alternatives - Amoxicillin/Ceftriaxone IV
Early Tx 10-21 days, otherwise 14-28 days
Prophylaxis - Not recommended, all must apply - Attached Tick identified as adult or nymph I.scapularis attached for >36 hrs, Prophylaxis can be started within 72 hrs of time tick removed, Ecologic info indicated local rate of infection of ticks is >or= to 20%, Doxycycline is not contraindicated. Administer single dose of Doxycycline to adults and children >or= 8 Y/O
Babesiosis
Nymph stage I.scapularis carry B. microti - transmitted via Tick Bites, blood transfusions, and congenitally (rare) - Cannot be transmitted from person to person - Primarily in NE and Upper MW, often Co-infected w/ Lyme.
Clin Man = Asymptomatic to progressively fatal - Flu-like symptoms - Hemolytic Anemia (Jaundice, Dark Urine) - Rash Uncommon
Life-threatening in Asplenic, weakened immune systems, liver or kidney disease, and the elderly.
Complications - Sepsis, Hemolytic Anemia, thrombocytopenia, Disseminated Intravascular Coagulation (DIC), multi-organ failure, and death.
Diag = High Index of suspicion (due to non-specific presentation), CBC/hemolytic anemia labs (Thrombocytopenia and anemia), Peripheral smear (may look similar to malaria “Maltese cross”), IFA and PCR can be utilized.
Tx = Atovaquone+Azithromycin or Clindamycin+Quinine, Antipyretics, Vasopressors, Blood transfusions (supporting anemia), Exchange transfusions (critically ill), Ventilation, Dialysis.
Educate PT, no blood donation!
Only Tick Bonre Illness not to get Doxycycline
Ehrlichiosis
Name to describe disease caused by multiple parasites - Spread through bite of infected Tick or Blood transfussion - Human granulocytic anaplasmosis (HGA), Human monocytic ehrlichiosis (HE).
9 day incubation period - Majority cases June/July, Only adult and Nymphal ticks spread - Missouri, Arkansas, New York, and Virginia >50% of cases followed by SE and South Central US - Men > Women - 60-69 Y/O - Compromised immune system more susceptible.
Si/Sx = 1-2 weeks post bite - Malaise, rigors, nausea, high fevers, headache, Rash (infrequent if present consider co-infection) - Immunocompromised PTs can have Severe presentations.
Dx = CBC (Leukopenia, thrombocytopenia), CMP (abnormal LFTs), Peripheral Smear (Bacteria in the Leukocytes), Polymerase Chain Reaction (PCR) - Identify specific genes unique to Ehelichiosis - mostly sensitive in the first week, Indirect Fluorescent Antibody (IFA) - not commonly used - Measure antibody to the bacteria - can take 3 weeks for result.
Tx = First-line: Doxycycline 100mg PO BID 10-14 days or until 3 days after defervescence, Rifampin approved for pregnant women.
Do not wait for confirmation if you have high suspicion, lack of improvement after 48 Hrs suggest alternative Dx.
Complications = Confusion/seizures/coma, Hemorrhage, Heart Failure, Respiratory Failure, Kidney Failure, Septic Shock
Anaplasmosis
Majority of cases Summer June/July - VT, ME, RI, MN, WI, NH, NY 90% of cases - Often misdiagnosed as ehrlichiosis - Spread via Tick Bite, Blood transfusion (rare) - Males >40 Y/O - Weakened Immune System - Residence or time spent in tick habitats (contact with white tail deer/white foot mouse)
Si/Sx = 1-2 weeks after bite - Warly illness 1-5 days: Fevers, Chills, Severe Headache, Myalgia, Nausea, Vomiting, Diarrhea, Anorexia - Late Illness: Respiratory Failure, Bleeding Problems, Organ Failure, Death (rare <1%)
Dx = CBC (Leukopenia, THrombocytopenia), CMP (abnormal LFTs), Peripheral Smear (bacteria in the monocytes, don’t confuse with ehrlichiosis), PCR - Identify specific genes unique to Anaplasmosis- mostly sensitive in the first week, IFA - not commonly used - Measure antibody to the bacteria - can take 3 weeks for result.
Tx = Doxyxycline (new evidence supports use in all ages?) 100mg PO BID and Rifampin in pregnant and Doxycycline allergy.
**Same Treatment as Ehrlichiosis
Rocky Mountain Spotted Fever (RMSF)
Most cases outside the Rocky Mountains - Obligate gram neg coccobacilli which multiplies within eukaryotic cells - Tropism for Vascular endothelial cells - Direct Vascular injury - INC vascular permeability - activation of Clotting factor - Hypovolemia, Hyponatremia, Reduced Tissue Perfusion.
Transmission after attached for 6-10 hrs - incubation 2-14 days - Occurs throughout the US, Mexico, central/south America - SE and South Central US - Spring and early summer (April thru September) - Fatality highest in <4 and >or= 60 Y/O
Risk = INC incidence in <10 and 40-60 Y/O, Frequent exposure to dogs, reside near wooded/high grass areas, Amer Indian.
Rocky Mountain Spotted Fever (RMSF): Clinical Manifestations, Signs, and Symptoms
Clin Man = Blanching erythematous rash w/ macules 1-4 mm in size that become petechial (bleeding under the skin) over time, onset 3-5th day of illness - 88-90% of PTs have a rash - Spotless RMSF may be severe and have fatal outcomes.
Si/Sx = appear 2-14 days after the bite, rash appears 3-5th day, is left untreated RMSF can cause severe multiorgan dysfunction and fatality rates of 73% - Rash initially involves wrist and ankles, spreading centrally to arms/legs/trunk, involves palms/soles - Facial flushing, conjunctival injection, and hard palate lesions may occur - ARDS and necrotizing vasculitis are signs of concern.
Early non-specific symptoms = Fever (often severe), Headache, Malaise, Myalgias, Arthralgias, Nausea +/- vomiting, Abdominal pain - Other symptoms = Cough, Bleeding, Edema (especially children), Confusion, Focal Nuero signs, Seizures, Conjunctivitis, Retinal abnormalities (rare).
Rocky Mountain Spotted Fever (RMSF): Major complications and PE findings.
Major complications = Encephalitis, noncardiogenic pulmonary edema, Adult Respiratory distress syndrome, Cardiac arythmias, Coagulopathy, GI Bleeding, Skin necrosis
Physical Exam Findings = Rash (common in 90% of PTs), Pedal Edema (especially in children), Confusion, Conjunctival erythema, Retinal abnormalities, Meningismus, Abnormal mentation, Focal Neuro Deficits, Gangrene of the digits/ears/scrotum
Rocky Mountain Spotted Fever (RMSF): Diagnostic studies, Differential
Labs :Normal WBC at presentation - As disease progresses Thrombocytopenia/Low fibrinogen/elevated fibrin sl=plit products (FSP)/Hypernatremia/Elevated serum aminotransferases and bilirubin/Azotemia/Prolonged PTT and PT
Chest X-ray: Interstitial infiltrates consistent with early pulmonary edema
Echocardiographic studies: Minimal myocardial dysfunction and normal pulmonary wedge pressure measurements during intensive care monitoring
Differential = Nonspecific viral illness/Other tick-borne illness/Meningococcal meningitis (rash looks similar)/Est nile virus meningitis or encephalitis/meningitis/thrombotic thrombocytopenic purpura (TTP)/Measles/Infectious Mononucleosis/Primary HIV
Rocky Mountain Spotted Fever (RMSF): Diagnosis and Treatment
Dx = Presumptive based on clinical signs/symptoms (difficult with long differential) - IFA assay for IgG Rickettsii antigen (Not present during the initial weeks of the illness)- IgM only available through some labs (not as specific) - Positive PCR helpful but deosn’t rule out negative as may not have large amounts of DNA in blood as it is invasive of endothelial - Special stain on biopsy specimen.
Tx = Therapy should be initiated w/in 5 days of symptom onset - Nonpregnant adults (Doxyxyxline/Chloramphenicol) - Pregnant Women (Chloramphenicol if not 3rd trimester) - Continue antibiotics for 3 days after PT becomes afebrile - Supportive care for critically ill
Doxycycline 100 mg PO BID for 10-14 days
Chloramphenicol 50-100mg/kg/day in 4 divided doses for 4-10 days
Response to therapy typically quick, Mild illness - typically defervesce w/in 48-72 Hrs, Severe Illness - may remain critically ill and febrile for up to 5 days after therapy initiation.
Mortality 3-5% in treated - Older native Americans w delay in antibiotics at higher risk of death. PTs who survive initial episode generally recover completely and gain immunity.
Rabies: Etiology, Epidemiology
Spread through saliva - Bites to head/face have greatest risk of infection - Can be transmitted w/out bite in some cases - Most common infected animals Bats/Racoons/Skunks/Foxes
Epidemiology = Worldwide with following exceptions - Antarctica/New Zealand/Japan/Sweden/Norway/Spain/Some Caribbean Island/Hawaii
Rabies: Transmission
Through Saliva, often in a bite - Virus multiplies locally in myocytes at wound site - Virus binds to nicotinic AcH receptors at NMJ - Virus travels w/in axons in PNS to the CNS - Virus replicates in motor neurons of the spinal cord and local dorsal root ganglia rapidly ascending to brain - Virus infects brain’s neurons - Virus spreads to salivary glands/skin/cornea/other organs, saliva infectious for up to 2 weeks before symptoms appear.
Rabies Clinical Manifestations
Incubation between 1-3 months - Prodromal symptoms few days to a week (Lowgrade Fever/Chills/Malaise/Myalgias/weakness/Fatigue/Anorexia/Sore throat/Vomiting/Headache/Photophobia
Disease evolves into Encephalatic (furious Rabies) 80% or Paralytic (dumb) <20%
Furious Rabies - Fever, Hydrophobia (33-50%), Pharyngeal spasms, Hyperactivity of muscle subsiding to paralysis, Autonomic instability (Hypersalivation/lacrimation/sweating/“goose flesh“/dilation of pupil), Agitation and combativeness, Coma, Death, Aerophobia (9%)
Dumb Rabies - Ascending paralysis (mimics Guilain barre syndrome), Flaccid paralysis starting in bitten limb then spreading, Headache, Pain, Nuchal rigidity, Cranial Nerve Palsies
Rabies Physical Exam, Studies
Physical Exam = Bite (infected w/erythema/pus), Mental Status Change (Agitation), Increased muscular tone, Increased Tendon Reflexes with extensor plantar response and fasciculations (will be seen in encephalitis), Nuchal rigidity, Flaccid Paralysis w/ generalized areflexia and loss od deep tendon reflexes (will be seen in paralytic), Tachycardia, Dilated Pupils, Increased lacrimation
Studies = Clinical suspicion, no one test (multiple tests required involve CDC)
- Rabies serum antibody titer (won’t be positive until later in course)
- Spinal Tap: elevated protein, normal glucose, anti-rabies antibodies
- Skin Biopsy
- Saliva
CT Head (Cerebral Edema)
Post Mortem Testing
Rabies Treatment, Prognosis
Tx = Pre-exposure Vacc: 3 IM injections given at days 0,7, and 21 or 28
Post Exposure Vacc: Wound should be cleaned immediately
Persons not previously immunized:
- Immunocompetent: 4 IM injections given at days 0, 3, 7, and 14
- Immunocompromised: 5 IM injections given at days 0, 3, 7, 14, and 28
Persons who have been vaccinated prior should receive the pre-exposure series again
Prognosis = If not treated most Pts die w/in 2 weeks after coma - Since april 2019 there have only been 25 documented cases of survival
Treatment choices:
- Palliative care
- Immunotherapies (rabies vaccine or human rabies immune globulin)
- Antiviral therapies
- Neuroprotective therapies
Malaria Epidemiology, Etiology
Endemic through most of the tropics (most cases occur in Subsaharan Africa/SE Asia and Indian subcontinent), May thru Dec - Vector is mosquito (usually between dusk and dawn) - Rarely (congenital /blood transfusion/contaminated needle sharing/organ transplant)
Bite deposits Sporozoites which collect in the liver where they can remain dormant for years - RBCs infected in Liver go into circulation - PT can be asymptomatic 12-35 days
Malaria Uncomplicated/Severe Clinical presentation, Physical Exam
Uncomplicated: Cycle of cold, hot, sweating occurring every 2 or 3 days
Fever/Tachycardia/Tachypnea/Chills/Malaise/Fatigue/Diaphoresis/Head Ache/Cough/Anorexia/NVD/Arthralgias and Myalagias/Anemia
Severe: “Cerebral Malaria” - Confusion/Obtunded/Seizures/Coma - Hemolysis/Hemoglobinuria - ARDS: Inflammation in lungs which impairs O2 exchange - Coagulopathy - Hypotension - AKI - Hyperparasitemia >5% of RBCs infected (palpable spleen) - Metabolic acidosis - Hypoglycemia (especially in pregnant females)
Physical Exam = Diaphoreses, Tachycardia, Tachypnea, Palpable Spleen, Hepatomegaly, Pale from anemia/Jaundice, Weakness
Malaria Diagnosis, Treatment
Suspect with febrile illness + travel to endemic region
Rapid diagnostic test (RDT): if + blood smear evidence of hemozoin-breakdown products
Smear for speciation & degree of parasitemia, if negative at first continue testing each day for 2 more days.
Uncomplicated: Parasitemia <5% & no organ dysfunction
Complicated: Parasitemia >10% w.organ dysfunction
Anemia/Thrombocytopenia/Elevated (Transaminases/BUN/Creatinine)
Tx = Depends on Species of Plasmodium, the area of inoculation, drug resistance, clinical status of PT, Medical Comorbidities, pregnancy and G6PD
Chloroquine, Malarone (Atovaquone + Proguanil), Coartem (artemether + Lomefantone), Mefloquine, Quinine (+Doxycycline, Clindamycin or Tetracycline), Artesunate (must get through the CDC), Primoquine and Tafenoquine are active against the dormant liver forms and prevent relapses
Usually Complete cure after Tx; however some forms lay dormant in liver for years and can have multiple relapses, Immunity after being infected several times.
