Arthropod Bites II Flashcards
Colorado Tick Fever Virus Genome and Structure
Non‐enveloped, dsRNA virus
Colorado Tick Fever Virus Vector and transmission
- Tick (Dermacentor andersoni)
- Brief tick encounters (unlike Borrelia, Babesia, etc.)
- Focus: mountainous regions of western US
- Seasonal (May‐July)
- Virus replicates in bone marrow stem cells
Colorado Tick Fever Virus Clinical
- High fever, chills, arthralgia, myalgia, headache (1‐3 days)
- “Saddleback fever”
- Prolonged recovery: weeks to months
Colorado Tick Fever Virus Diagnosis and control
-Travel history, serology, virus isolation from blood -Prevent tick bites
Malaria (Plasmodium spp.) Symptoms
-Non‐specific febrile illness, with fever, chills,
headache, body aches, weakness, N/V/D
-Severe: Organ damage secondary to RBC lysis and accumulation, Hemoglobinuria; kidney failure, Acute respiratory distress syndrome
Malaria Diagnosis
Visualization of parasites in blood smear
Babesia microti General
Protozoan and sporazoan
Babesia microti Lifecycle
- Vector: “Deer tick”: Ixodes scapularis
- Reservoir: mice
Babesia microti Clinical course
- Replicates in erythrocytes, and RBC lysis (hemolytic anemia)
- 1‐4 week incubation period
- Fever, malaise, headache, chills, fatigue
- A febrile hemolytic anemia
- 2‐4 week recovery
Babesia microti Complications
Renal failure
Babesia microti Diagnosis
Thin blood smears & parasite visualization
Babesia microti Ring forms
-ONLY ring forms are seen in blood smears
-RBCs may contain multiple rings (like P. falciparum)
-Can be vacuolated (white areas within ring, below)
Often appear in PAIRS OR TETRADS (MALTESE CROSS)
Also lack pigmentation or stippling
RBCs are also not enlarged (unlike P. vivax, ovale)
Babesia microti control
Avoid tick bites
Yersinia pestis General
- Gram (‐) facultative rod
- Closed “safety‐pin” appearance in aspirates of swollen lymph nodes (buboes)
Yersinia pestis Pathogenesis
- Purpura, ecchymosis, &/or gangrene
- Bubonic Plague: Buboes painful, tender, enlarged lymph nodes
- Multisystem involvement: Spleen, liver, lungs, CNS
Yersinia pestis Lab identification
- Microscope or culture
- Lymph node aspirate or sputum
- Giemsa, fluorescent Ab staining
Yersinia pestis Prevention
-Rodent control, vaccine
Coxiella burnetii: Q Fever General
- Outbreaks in Europe
- Obligate intracellular pathogen (Formerly Rickettsiae)
- Gram negative pleomorphic coccobacillus
- Does not Gram stain: Gimenez stain used
- 2 forms: Small Cell Variant and LCV
Coxiella burnetii: Q Fever Reservoirs/Transmission
- Sheep, goats, cattle, dogs, cats, birds, rodents, ticks, NO ARTHROPOD VECTOR
- Infected animals shed bacteria: in feces, urine, milk
- Contract by aerosols (or ingestion)
Coxiella burnetii: Q Fever Pathogenesis
Alveolar macrophages primary host cell
Acidic pH (4.5) in phagolysosome SCV LCV
Slow intracellular growth of LCV to generate LCV and SCV
SCV released and infect new cells
Antigenic variation: two phase variants
Phase I: full LPS; more infectious
Higher antibody response during chronic infections
Phase II: short LPS with no O‐antigen
Higher antibody response during acute infections
Coxiella burnetii: Q Fever Clinical Symptoms
- Nationally Reportable
- Asymptomatic
- Incubation period 20 days
- Acute: chest pain, clay‐colored stool, cough, fever, headache, jaundice, muscle pain, rash (not common)
- Chronic: chills, fatigue, night sweats, fever, culture‐negative endocarditis, osteomyelitis
Yersinia pestis Virulence factors
-capsule, LPS, adhesins, type III secretion, other protein toxins
Yersinia pestis Reservoirs
Reservoir(s): rodents, Xeopsylla cheopsis (rat flea)
-Bacterial replication occurs in flea gut
Coxiella burnetii
- SEROLOGY
- Dont culture-highly contagious. Lvl 3 clearance
Brucella
- Facultative intracellular pathogens, aerobic, slow growing, Gram‐negative coccobacilli or small rods, Catalase and oxidase positive
- Chronic animal infections?: Sheep, goats, cattle, deer, elk, pigs, dogs, others
Brucella Diagnosis
- Blood cultures (gold standard), but bone marrow cultures more sensitive
- Serology
Brucella Pathogenesis
- Multiply in phagocytic cells
- Non‐endotoxic LPS blocks innate immune responses
Brucella Clinical symptoms
- flu‐like illness
- Severe: CNS involvement, endocarditis
- Chronic form: recurrent fevers, joint pain, and fatigue
Leptospirosis General
Tightly coiled spirochetes; flagellated (2 flagella)
Leptospirosis Transmission
Ingestion; direct contact
Leptospirosis Clinical Manifestations
- Fever, flu‐like illness
- Hepatitis, jaundice & hemorrhage in the liver;
- Uremia & bacteriuria in the kidney
- Aseptic meningitis
Leptospirosis Lab identification
- Culture (Blood, CSF & urine) to check for rise in agglutinating Ab
Leptospirosis Prevention
-Rodent control, protective clothing, prophylactic penicillin
