tickborne illnesses and hematologic consequences - Stillwell Flashcards
1
Q
spotted fevers
A
- Rocky Mountain spotted fever
2. American tick bite fever
2
Q
tick borne illnesses
A
- triad of disease –> fever, headache, myalgia**
- any month of the year in western AR**
- don’t always get a rash
- serologies take forever, treat 1st***
3
Q
doxycycline/tetracycline**
A
-the only antimicrobial antibiotics that treat all tick-borne bacterial illnesses**
4
Q
Rocky Mountain spotted fever (RMSF)
A
- organism: rickettsia rickettsia ** (intracellular)
- attacks vascular endothelial cells –> permeability and petechia**
- where?: north, central, South America; AR, OK, TN, NC in the US
- ticks: dermacentor variabilis (American dog tick), dermacentor Andersoni (Rocky Mountain wood tick), Rhipicephalus sanguineus (brown dog tick)
- transmission 6 hr after tick bite from salivary glands**
- incubation (5-7 days) after bite** (usual for most ticks)
- high fever, headache, myalgia**
- spotless rash in 80-90% of cases**
- nausea, vomiting, diarrhea, ab pain early**
- rash on wrists/ankles spreading to palms/soles/trunk** –> progress to petechia, necrosis, gangrene, edema
- 1/3 with hepatitis (elevated liver enzymes) and jaundice**
- diagnosis: weil-felix agglutination test for antigens, serology with IgM/IgG (most common; takes 2 weeks to become +), PCR (not sensitive)
- elevated transaminase (liver enzyme) –> indicate damage**
- normal WBC count
- “shoot 1st” –> give doxycycline/tetracycline**
5
Q
why should you not wait to treat people until antibodies are +?
A
- take awhile to become +
- need to treat immediately or it may be too late
6
Q
American tick bite fever
A
- organism: rickettsia parkeri
- where?: south/southeastern US
- ticks: Amblyomma maculatum (gulf coast tick); A. americanum (lone star tick - dot in center of back)**
- less severe than RMSF
- unlike RMSF, eschar seen at tick bite 90% of time***
- may see vesiculopapular rash**
- treat: doxycycline*
7
Q
what is the most common tick bite around here?
A
- amblyomma americanum (lone star tick)**
- dot in the center of back
8
Q
Ehrlichiosis (Human monocytes ehrlichiosis - HME)
A
- organism: ehrlichia chaffeensis** –> bacteria that lives in vacuoles (morulae) of monocytes and Macs**
- where?: worldwide, south/southeast US
- tick: amblyomma americanum (lone star tick)** ; also Ixodes pacificus (western black legged tick) and Ixodes scapularis (deer tick)
- invades bloodstream and evades host defenses, but no endothelial injury like RMSF**
- may lead to toxic shock, high liver enzymes, or granulomas
- only 1/3 have clinical illness (usually cleared)**
- 1/3 people get rash (mild, palms/soles) - children common
- severe in elderly, immunosuppressed –> multi organ failure
- leukopenia, thrombocytopenia, elevated transaminase, blood smear showing morulae in monocytes/Macs**
- patchy infiltrates on chest X ray
- serology (antibody) - takes 2-3 weeks to become +**
- treat: doxycycline/tetracycline
9
Q
Anaplasmosis (human granulocytic anaplasmosis HGA and human granulocytic ehrlichiosis HGE)
A
- organism: anaplasma phagocytophilum**; also ehrlichia ewingii (canine granulocytic ehrlichiosis)
- bacteria living in morula of granulocytes**
- E. ewingii usually in immunocompromised
- where?: north/northeast US, California, Europe
- tick: ixodes scapularis (deer tick)** and ixodes pacificus (western blacklegged tick)**
- similar to HME in symptoms (except no rash), labs, and treatment
10
Q
tularemia
A
- organism: francisella tularensis (originally bacterium tularense) and F. holarctica
- won’t grow on gram neg. media like MacConkey**
- makes endotoxin, no exotoxin
- if it grows in lab –> treat everyone with doxycycline bc it gets aerosolized and inhaled**
- where?: worldwide, AR, OK, KS, MO
- ticks: 13 strains; American dog, rocky mountain wood, pacific coast dog, lone star
- passed by ticks east of Rocky Mountains**
- passed by tabanids (deer/horse flies) in western states**
- also passed by mosquitos
- reservoir: many animals (rabbits, rodents, squirrels, deer)**
- replicate in macrophages (protection against reinfection once recovered by cell-mediated immunity)
- sudden fever, headache, myalgia/arthralgia –> relapsing fever**
- pulse-temp dissociation (Faget’s sign)***
- skin lesions at inoculation site that ulcerate with black eschars, slow healing –> can progress to lymphadenopathy**
- diagnosis: serology antibodies (main) - takes weeks, remain + for years, can cross react with brucellosis and RMSF
- labs: granulomas, leukocytosis, thrombocytosis, elevated transaminase and ESR, CSR***
11
Q
tularemia types**
A
- ulceroglandular and glandular** (80%) –> localized lymphadenopathy
- typhoidal - multisystem symptoms (sepsis)
- pneumonic - atypical pneumonia
- oropharyngeal and GI
- oculoglandular (inoculated by conjunctiva)
12
Q
tularemia treatment
A
- quinolones - good intracellular activity**
- doxycycline - low relapse rate**
- chloramphenicol - high relapse rate
- aminoglycosides (for serious infection) - Gentamicin**
13
Q
Q fever
A
- organism: coxiella burnetii**
- biphasic antigen presentation** (phase 1 antigen when infected; phase 2 antigen in non-infective)
- resistant to environmental stress; can be inhaled
- where?: zoonosis worldwide (except Antarctica), AR, OK
- exposure to birth products (ex. placenta, amniotic fluid), urine, feces, milk***
- ticks: lone star, rocky mountain wood, brown dog
- loves low pH of phagolysosomes of Macs/monocytes
- elevated transaminase 85% of time**; also high ESR, CRP
- low Na+ with SIADH
- diagnose: serology antibody by 3rd week** (phase II IgG/M/A develop more than a year; phase I develop later with chronic disease)** –> OPPOSITE of normal in acute Q fever; normal with chronic Q fever
- treat: doxycycline/tetracycline; double drug coverage for chronic Q fever (doxy/hydroxychloroquine or doxy/quinolone)
- need surgical debridement
- sulfa drugs + folic acid during pregnancy
- QVAX (killed vaccine) for abbatoir workers
14
Q
acute Q fever
A
- asymptomatic
- self-limited febrile illness
- if symptomatic –> atypical pneumonia, acute granulomatous hepatitis (“doughnut like”), high liver enzymes, spontaneous abortion/premature birth***
- no intracellular growth, but high inflammatory response
- phase II antibodies higher than phase I
15
Q
chronic Q fever
A
- infective endocarditis/prosthetic infection (think about heart murmur)
- hepatitis, osteomyelitis, lymphadenopathy
- persistent intracellular growth in Macs/monocytes, decreased T cell response, little inflammation
- phase I antibodies higher than phase II
16
Q
STARI (southern tick associated rash illness)
A
- similar to Lyme disease, but a different organism and less sever (no inflammatory arthritis or cardiac/neurologic deficits)
- organism: Borrelia lonestari??
- where?: south and Southeast US
- tick: amblyomma americanum (lone star tick)***
- targetoid erythema chronicum migrans (ECM) skin lesion**
- smaller lesions and less multiple than lyme**
- treat: doxycycline
