Tick talk Hurt

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Published on January 4, 2008

Author: Felipe

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Bugs You Get from Bugs:  Bugs You Get from Bugs ID Fellows’ Board Review Christopher Hurt, MD May 18, 2007 Outline:  Outline Borrelial diseases Relapsing fever and Lyme disease Plague Rickettsial diseases Rocky Mountain spotted fever, rickettsialpox Epidemic, endemic, and scrub typhus Q fever Ehrlichioses (HME and HGA) Babesiosis Other tick-borne illnesses Tick paralysis, STARI, Powassan encephalitis Borrelial diseases:  Borrelial diseases Relapsing fever:  Relapsing fever Two distinct entities: one in Africa, one in US Both have relapsing course of fever related to changing antigens on surface of Borrelia spp. African variety may have only a single relapse African epidemic relapsing fever:  African epidemic relapsing fever Caused by Borrelia recurrentis Transmitted when body lice are crushed into bite wound Pediculus humanus humanus, affectionately nicknamed the “seam squirrel” Social upheaval, unsanitary conditions, populations in flux Pts with epidemic dz are usually more toxic Endemic relapsing fever:  Endemic relapsing fever Caused by any of 15 Borrelia spp. Nomenclature matches that of host soft-tick (B.parkeri and Ornithodoros parkeri) These ticks are different! Nighttime feeders SHORT bloodmeals (10-15 mins) No visible mouthparts O.moubata (African) Endemic relapsing fever:  Endemic relapsing fever Finicky ticks Coniferous forests Rodents + ticks + people WA, CA (Tahoe), limestone caves in TX, north rim of Grand Canyon Relapses may occur as many as 12 times before cause identified Endemic relapsing fever:  Endemic relapsing fever Diagnosis Seen on peripheral smears (unique among spirochetes!) May cross-react with Lyme serologies Treatment PCN, tetracycline, erythromycin Epidemic? 500mg e-mycin x1 Endemic? 7-10d Jarisch-Herxheimer is FREQUENT Lyme borreliosis:  Lyme borreliosis Borrelia burgdorferi Spirochete Cx possible in artificial media, from blood or ECM rash bx Europe has 3 circulating genospecies of “sensu lato” B.burgdorferi sensu stricto B.garinii – more CNS dz B.afzelii – more skin dz Lymphocytoma cutis Acrodermatitis chronica atrophicans Ixodes scapularis:  Ixodes scapularis Hard “black-legged tick” Associated with 2 other pathogens Babesia microti (in NE) Anaplasma phagocytophilum (HGA) Erythema chronicum migrans (ECM):  Erythema chronicum migrans (ECM) EARLY finding About 1/3 will p/w macular rash, not ECM Draw circle around it, then see pt again (if ? exists) Rash spreads as spirochetes move through the skin Other early complications:  Other early complications Early disseminated is somewhat like secondary syphilis Bell’s palsy can occur with or without any other CNS signs LP is important if more than just Bell’s palsy High-degree atrioventricular blocks NOT an indication for PPM placement… but may need a temporary wire Late complications:  Late complications Arthritis asymmetric, large-joint, often abrupt onset Swollen, tender, but not painful as in septic joint Fluid = PMN predom, increased protein, normal glucose Lyme encephalopathy Subtle cognitive defects Immune-mediated damage? Lyme borreliosis:  Lyme borreliosis Diagnosis Culture medium is available, but not easy to get Serology is key – CDC’s two-step approach IFA/ELISA screen (2 of 3 bands) with WB (5 of 10) If sick > 1 month, don’t bother sending IgM Treatment Doxycycline, amoxicillin, cefuroxime (all oral) Macrolides are last line therapy For carditis or CNS disease, IV ceftriaxone Isolated Bell’s palsy can safely get just doxy Prophylaxis for Lyme:  Prophylaxis for Lyme Very specific group is appropriate Ixodes tick attached for over 36h Patient presents within 72h after bite 200mg doxycycline orally x1 given Plague:  Plague Yersinia pestis:  Yersinia pestis Gram-negative, with safety-pin appearance May appear in peripheral smears, also with Wayson stain Vectors and reservoirs:  Vectors and reservoirs Fleas get their teensy little esophagi blocked, and then puke into the bite site Domesticated animals may be indirect vectors Cats may tangle with prairie dog, e.g. Person-to-person is possible Isolate on droplet precautions for 48h Geographic distribution:  Geographic distribution Came to US via San Francisco in early 1900s Entire West is endemic “Four Corners” area of US desert SW Veterinarians are at particularly high risk Cats that may have encountered rodents Cougars, bobcats also can carry plague Presentations of plague:  Presentations of plague Bubonic (60-75%) Rapid progression, voluntary limb immobilization Buboes can be “washed” Not purulent (as in tularemia) Septicemic (25%) Y.pestis proliferates rapidly in blood… leading to SIRS, DIC [2ndary] Pneumonic (10%) Dissemination from bubo Highly droplet-contagious CXR out of proportion to Pex Rarely meningitis, pharyngitis Treatment:  Treatment Streptomycin (10d) Tetracycline (10d) Gentamicin (10d) For prophylaxis of face-to-contact, 7d oral tx Rickettsial diseases:  Rickettsial diseases Rickettsiae:  Rickettsiae Obligate intracellular Gram-negative coccobacilli Except for Coxiella burnetii Multiply by binary fission Contain both DNA and RNA Four groups: spotted fever, typhus, ehrlichioses, Q fever Typhus, spotted fever groups both produce endotoxin Manifestations predominantly due to vasculitis Almost all have an insect or arachnid vector Rickettsiae:  Rickettsiae Rocky Mountain Spotted Fever:  Rocky Mountain Spotted Fever Rickettsia rickettsii Spotted fever group Eastern US and AR (first case in Idaho…) AZ cases new in 2006 Pathogenesis attachment to vascular endothelium proliferation and cell-kill increased vascular permeability Clinical manifestations:  Clinical manifestations Fever 100% Headache (severe) 79-91% Rash 90% Spotless more often in elderly and black pts Myalgias 70-80% Neurologic sxs 40-50% Focal deficits, transient deafness, meningismus, photophobia Thrombocytopenia 30-50% Diagnosis and treatment:  Diagnosis and treatment Clinical and epidemiologic data Microbiologic isolation unlikely Immunohistochem of bxs H&E will show vasculitis Serology (or PCR) IFA, EIA Treatment with doxycycline or chloramphenicol AVOID DELAY AGs, ß-lactams, macrolides, TMP/SMX no effect Rickettsialpox:  Rickettsialpox Rickettsia akari Urban disease – current IVDU, frequent injectors, shooting galleries Duke reported a case in homeless patient Eschar (tache noir), chills, HA, papulovesicular rash More cases in NYC after 9/11… May mimic cutaneous anthrax Epidemic typhus:  Epidemic typhus Rickettsia prowazekii Outbreaks w/social upheaval Those lovely seam squirrels again… Abrupt onset fever, chills, myalgias, HA Dx clinical or with bx Tx doxycycline or CAP Brill-Zinsser disease Recrudescence years after original attack Dachau Scrub typhus:  Scrub typhus Orientia tsutsugamushi Sudden onset fever, HA, myalgia, LAD, eschar, late-onset rash SE Asia Chiggers (trombiculid mites) Dx clinical, PCR, immunohistochem Tx primarily single-dose doxycycline or FQ Q fever:  Q fever Coxiella burnetii ONLY rickettsial bug that can live extracellularly Inhalation is main transmission, but also (rarely) ticks Vets dealing with pregnant animals (± dead) Concern for bioterrorism capacity… only 40% get acute dz (hepatitis, pneumonia) Chronic infection can cause culture-negative IE Ehrlichial diseases:  Ehrlichial diseases Obligate intracellular Gram-negatives grow in vacuoles HME - monocytes HGA - granulocytes Rickettsiae grow in cytoplasm Micro-colonies called morulae Bites of infected ticks transmit First recognized among dogs, causing “tropical pancytopenia” First human ehrlichiosis in 1986 Human monocytic ehrlichiosis:  Human monocytic ehrlichiosis Ehrlichia chaffeensis AR, MO, OK, TX, north FL, VA Hard ticks… white-tail deer Ixodes scapularis and pacificus Amblyomma americanum (Lone star tick) First case 1990, from soldier at Ft Chaffee in AR Tick bites, exposure to wildlife, and golfing Human granulocytic anaplasmosis:  Human granulocytic anaplasmosis Anaplasma phagocytophilum Used to be E.equi WI, MN, CT, NY, MA, CA, FL Ixodes ticks… deer and white-foot mice Up to 25% of ticks in endemic areas co-infected with B.burgdorferi and A.phagocytophilum First described in 1994 Dumler JS. Emerg Inf Dis. 11;12:1828 Clinical manifestations:  Clinical manifestations Symptoms can’t distinguish btw HME and HGA Incubation period 1-2 weeks after tick bite About 2/3 of patients will develop: Abrupt-onset fever (often >39), ± rigors HA, myalgias, malaise, nausea, cough, arthralgias Most (over 75%) will report tick bite Rash (macular, papular, rarely petechial) in 33% If rash is present in Anaplasma infection, consider co-infection with Lyme, RMSF, or misdx of actual meningococcemia Clinical course:  Clinical course Leukopenia (± neutropenia in HGA), thrombocytopenia Elevated liver enzymes Transaminases, alk phos, LDH CSF may have pleocytosis in HME Complications? Seizures, coma, renal, respiratory failure, CHF Low mortality overall (2.5% HME, 7-10% HGA) 6 of 13 HIV+ patients with HME in one series died! DDx = RMSF, TTP, heme malignancy, mono Diagnosis and treatment:  Diagnosis and treatment Diagnosis made in buffy coat or on peripheral smear HGA more commonly has peripheral cells with morulae than HME does Serology with IFA, or PCR Tx is with doxycycline 200/d in 2 divided doses for at least 7d, or for 3-5d after defervescence Rifampin if doxy allergic, or pregnant Babesiosis:  Babesiosis Babesiosis:  Babesiosis Babesia microti and Babesia divergens Worldwise distribution In US, NE and Midwest – B.microti, Ixodes ticks and white-footed mouse Tick infects mouse with sporozoites (which reproduced asexually in RBCs) Sporozoites escape to blood stream & form male/female gametes that are taken into tick during bloodmeal In tick, gametes fuse and make more sporozoites Which one is from babesiosis?:  Which one is from babesiosis? Which one is from babesiosis?:  Which one is from babesiosis? Babesia’s intraerythrocytic rings are more variable in size compared to P.falciparum Tetrad or “Maltese cross” form is pathognomonic for Babesia. (4 budding merozoites) Babesia does not make pigment, while Plasmodium falciparum does. Clinical course:  Clinical course Many cases asymptomatic Incubation about 7d Very malaria-like Fever, chills, sweating, myalgias, fatigue Hepatosplenomegaly, hemolytic anemia More severe in immunocompromised, elderly B.divergens (European) may be more severe Tx = clindamycin plus quinine, or atovaquone plus azithromycin Other diseases:  Other diseases Other tick-borne illnesses:  Other tick-borne illnesses Tick paralysis NOT an infectious process… it’s like myasthenia April through June, Western US and Canada Dermacentor (wood and dog ticks) and Amblyomma (Lone star) Toxin in saliva of tick causes acute, painless, ascending flaccid paralysis - sensory intact Onset few days after bite… and resolves usually within 24h after removal of tick (diagnostic) Mortality rate up to 10% if respiratory involvement DDx includes Guillain-Barré, botulism Other tick-borne illnesses:  Other tick-borne illnesses Southern tick-associated rash illness (STARI) Rash similar to Lyme, but similarity ends there NO neurologic, arthritic, or chronic sxs from STARI Amblyomma (Lone star) tick is vector Distribution from TX through N FL, up to MO and over to VA, then thin rim up coast to Maine Agent unknown, but it’s NOT B.burgdorferi At one time thought to be B.lonestari If you (or a friend) have STARI, please call the CDC at (970) 221-6400 to participate in an IRB-approved protocol. You must be at least 4 yo. Other tick-borne illnesses:  Other tick-borne illnesses Powassan encephalitis Flavivirus encephalitis carried by non-scapularis Ixodes ticks… only short bloodmeal needed First described 1958; only 27 cases from ‘58 to ‘98 Between 9/99 and 7/01, 4 cases in ME and VT WNV testing was negative – and Powassan dx’d Clinically, most recent pts had: High fever (103-104.7), leukocytosis, ARF, anemia Onset of hemiplegia, ataxia, CN palsies, confusion CSF with lymphocytic pleocytosis, protein up MRIs all suggestive of microvascular ischemia or demyelinating disease Questions and cases:  Questions and cases Match the bug to the bug!:  Match the bug to the bug! Babesiosis Anaplasmosis / HGA Lyme disease Relapsing fever (USA) Plague Epidemic typhus STARI HME Match the bug to the bug!:  Match the bug to the bug! Babesiosis Anaplasmosis / HGA Lyme disease Relapsing fever (USA) Plague Epidemic typhus STARI HME Where are they?:  Where are they? Babesiosis Lyme disease Relapsing fever Plague RMSF Where are they?:  Where are they? Babesiosis Lyme disease Relapsing fever Plague RMSF Case 1:  Case 1 RL is a 45yo avid outdoorsman who travels every year to Lake Tahoe for a summer vacation. He and his family own a cabin there. About 1 week after returning, he develops several days’ history of fevers and chills, without any other localizing symptoms. His son has similar symptoms. CXR is normal. He recalls bites, but says he didn’t ever see any ticks to remove. He has had no rashes. The hematology lab calls you to come and look at the smear: Case 1 (cont’d):  Case 1 (cont’d) Case 1 (cont’d):  Case 1 (cont’d) What is your diagnosis? Acute syphilis Lyme disease RMSF Relapsing fever Endemic typhus Case 1 (cont’d):  Case 1 (cont’d) What is your diagnosis? Acute syphilis Lyme disease RMSF Relapsing fever Endemic typhus Case 2:  Case 2 BB is a 60yo woman for whom you are consulted when she is admitted to the ICU. She is unable to provide much history, given her newly purchased endotracheal tube. She presented alone to the ED with fever, rigors, prostration, and dyspnea on exertion. Her address is in Hyannis, MA. She is pale on exam and has labored breathing. Lab studies show an anemia, with Hgb 8.6. LDH and bilirubin are up; haptoglobin is down. She is febrile to 103°F. Automated blood count shows a flag for malaria. You look at the smear yourself: Case 2 (cont’d):  Case 2 (cont’d) Case 2 (cont’d):  Case 2 (cont’d) What is your diagnosis? Hemoglobinopathy Babesia divergens Plasmodium falciparum Babesia microti Borrelia burgdorferi Case 2 (cont’d):  Case 2 (cont’d) What is your diagnosis? Hemoglobinopathy Babesia divergens Plasmodium falciparum Babesia microti Borrelia burgdorferi Case 3:  Case 3 CK is a 32yo from Baltimore who is visiting family in Durham. He he has an extensive history of IVDU, including an episode of tricuspid valve endocarditis for which he received only antibiotic therapy, about 5 years ago. He presents to the ED with acute onset of fevers, chills, myalgia, and intense headache. The nurses can’t get a peripheral in him, so a central line is placed. LP is unrevealing, with normal OP. Case 3 (cont’d):  Case 3 (cont’d) Your physical exam reveals a diffuse but not confluent papulovesicular rash over the trunk and on the posterior aspect of his left calf has this lesion, measuring approximately 2cm across: Case 3 (cont’d):  Case 3 (cont’d) What is your diagnosis? Rickettsia prowazekii (epidemic typhus) Bartonella quintana (urban trench fever) Rickettsia rickettsii (RMSF) Bacillus anthracis (cutaneous anthrax) Rickettsia akari (rickettsialpox) Case 3 (cont’d):  Case 3 (cont’d) What is your diagnosis? Rickettsia prowazekii (epidemic typhus) Bartonella quintana (urban trench fever) Rickettsia rickettsii (RMSF) Bacillus anthracis (cutaneous anthrax) Rickettsia akari (rickettsialpox) Case 4:  Case 4 UW is a 62yo from Wilson, NC who presents with fever, chills, and HA about 10d after returning from a family reunion in northern Wisconsin. While on the trip, he went fly fishing with his brother, uncle, and father. He denies any recollection of tick bites, and has had no rash. He admits to significant myalgias and malaise. Labs reveal WBC low at 2.3, platelets somewhat low at 62K. Physical exam is unrevealing. Case 4 (cont’d):  Case 4 (cont’d) Careful examination of what specimen would most likely reveal the cause of this patient’s symptoms? Blood cultures Lumbar puncture CXR CBC/diff Sputum Case 4 (cont’d):  Case 4 (cont’d) Careful examination of what specimen would most likely reveal the cause of this patient’s symptoms? Blood cultures Lumbar puncture CXR CBC/diff Sputum Peripheral smear or buffy coat in HGA will show morulae… HME less likely on PBS to show it Slide70:  “Pull out, Betty! Pull out!… You’ve hit an artery!”

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