29 – Coxiella, Borrelia and Bartonella Flashcards
Coxiella microbiological characteristics
- Obligate intracellular parasites
- Doesn’t stain using Gram-stain
- Worldwide distribution EXCEPT New Zealand
- Not culturable using standard techniques
- Biocontainment level 3
- *requires specialized conditions in vitro (inoculation of embryonated eggs)
Borrelia microbiological characteristics
- Large spirochetes
- Small linear chromosome
- Biocontainment level 2
- On both continents (Europe and USA) for over 100 years
Bartonella microbiological characteristics
- Small Gram-negative coccobacilli
- Biocontainment level 2
Coxiella natural host or habitat
- Obligate parasite: host associated
- Infects wide variety of species
- Shed in milk, urine, feces, amniotic fluids at parturition
- Can survive in environment up to 150 days
Borrelia natural host or habitat
- Obligate parasites: host associated
- Associated with reservoir hosts and arthropod vectors
o Highly adapted to their specific arthropod vector - Transmission via tick bites=most likely by nymphs
Bartonella natural host or habitat
- Facultative intracellular parasite
o Erythrocyte and endothelial cell pathogens - Have principle animal reservoir
- Spread through vectors
- *Generally mild disease in reservoir host, pathology when incidental host infected
Coxiella burnetiid virulence factors
- Little known
- LPS: phase variation (antigenic variation that masques it from the immune system)
Borrelia burgdorferi virulence factors
- Outer surface proteins: attachment in tick host, allows organism to persist in gut between meals
- Surface lipoproteins: stimulate inflammation
- Porin-like proteins: adhesion
- Flagella; motility
Bartonella spp. virulence factors
- Type 4 secretion systems
- Bartonella effector proteins (BEPS): secreted into host cells and modulate physiology in favour of bacteria
o Induction of phagocytosis by host cells
o Prevention of apoptosis
Coxiella burnetii is a generalist parasite of eukaryotic cells and is found in
- Arthropods
- Reptiles
- Birds
- Mammals
What is Coxiella burnetii the agent of?
- Q fever
o Short ‘query’ fever
When Coxiella burnetii is present, there are high concentrations in placenta and fetal tissues
- Animals frequently eat these after birth
- Passes through GIT
- Excreted in feces
- Can be aerosolized as dust
Aerosol transmission of Coxiella burnetii is very important
- Very low infectious dose
- Enters lungs
- Replicates in pulmonary macrophages
- Disseminates throughout the body
Interesting life cycle of Coxiella burnetti (?)
- Small cell variant ‘eaten’ by macrophage
- Vacuoles acidifies, stimulating development of large cell variants
- By 2 days parasitophorous vacuole contains lots of replicated large CV
- By day 6, small CV reappear
- By 12 days, host cell lyses and small CV released
Coxiella burnetii in domestic animals are mild or non-apparent: clinical sings relate to sites of localization (ruminants)
- Reproductive and mammary tract: abortions and shedding in milk
o Sporadic abortions: sheep, goats, cattle, cats
o Placentitis
o fetal pathology: many
Fetal pathology with Coxiella burnetii (ruminants)
- hepatitis
- myocarditis
- interstitial pneumonia
How do you control Coxiella burnetii? (ruminants)
- Segregation of parturient ruminants
- Careful disposal of tissues
Vaccination for Coxiella burnetii (ruminants)
- Inactivated vaccines available
Coxiella burnetii in dogs and cats
- Most common sublclinical
- Affected dogs=SPLENOMEGALY most common
- Cats=abortions
o Has been associated with human outbreaks
o See fever, lethargy, anorexia 2 days following experimental infection
What does Coxiella burnetii in humans cause?
- Q-fever
- Incubation period: 3 weeks
- 50% infected=asymptomatic
- Acute febrile illness (flu like)
- Case fatality <2% of hospitalized patients
- *NOT notifiable in Canada
What are some serious complications that can occur with Coxiella burnetii in humans?
- Pneumonia
- Granulomatous hepatitis
- Myocarditis
- Abortion
There was large, multiyear outbreaks of Coxiella burnetii in humans in the Netherlands
- 2005: dairy goats
- 2007: human infections spiking
o Living downwind with important - Clusters of infections associated with psychiatric patients who had contact with lambs as part of therapy
How was Coxiella burnetii in humans in the Netherlands brought under control?
- Vaccination
- Manure management
o Removal
o Pasteurization
o NOT spreading on fields - Bulk tank milk surveillance
- Massive culling
Coxiella burnetii in humans is often acquired as occupational disease
- Farmers
- Abattoir workers
- Vets
- Lab workers
- *FOODBORNE: unpasteurized products
- *rarely associated with cats
How do you treat Coxiella burnetii in humans?
- Doxycycline
How do you prevent Coxiella burnetii in humans?
- Vaccine for high risk workers
Who are the only competent vectors of Borrelia burgdorferi, Lyme Disease?
- TICKS: North America
o I. scapularis
o I. pacificus - *ticks infected by biting reservoir host