Exam #8: Zoonotic & Vector Borne Bacterial Infections II Flashcards
List the characteristics of Borelia.
Long spirochetes
Neither Gram -/+ (Gram negative like)
Mircoaerophilic
What diseases do Borrelia cause?
- Lyme Disease
- Relapsing Fever
What species of Borrelia cause Lyme disease?
Borrelia burgdorferi
What is the leading vector-borne disease in the US?
Lyme Disease
What is the major vector of Lyme Disease?
Lxodes spp. (hard tick)
*hard ticks transmit Lyme disease
What animals are the reservoirs for Lyme Disease?
Mice
White-tailed deer
When is the early stage of Lyme Disease most frequently seen?
Summer
What are the symptoms of early stage 1 Lyme Disease?
Localized infection
- Starts as a macule or papule lesion that enlarges to a bull’s-eye rash called “erythema migrans”
- Malaise
- Fever
- Headache
- Myalgia
- Lymphadenopathy
*Erythema migrans is pathognomonic for Lyme Disease
What is the name of the bull’s eye rash?
Erythema migrans
What are the symptoms of early stage 2 Lyme Disease?
Disseminated Infection: bacteria disseminate via the bloostream
- Arthralgia
- Myalgia
- Cardiac dysfunction
- Neurologic signs consistent with meningitis and encephalitis
What are the symptoms of late stage Lyme Disease?
Arthritis
- One ore more joints with the knee being the joint most commonly infected
- Skin discoloration (grey & ashy)
- Neurologic complaints (numbness, memory loss)
How is Lyme Disease diagnosed?
- Symptoms
- physical findings
- hx of exposure
How is Lyme Disease streated?
Doxycycline & amoxicillin
How is Lyme Disease prevented?
Limit tick exposure
What causes epidemic relapsing fever?
Borrelia recurrentis
- Louse-borne (lice)
- this is NOT zoonotic
- tranmission is human to human via the louse
What causes endemic relapsing fever?
Borrelia hermsii
- Tick-borne
*This is most common in the US
Describe the pathogenesis of relapsing fever.
- Bite from a louse or tick
- Dissemination via multiple organs through bloodstream
- Evasion of the immune system via antigenic variation
- Infection results in febrile & afebrile cycles, hence “relapsing fever”
What are the symptoms of relapsing fever?
Chills Fever Headache Muscle ache Splenomegaly Hepatomegaly
Symptoms last 3-7 days resolve, and then return after 7 days
Outline the antigen/antibody presence in blood smear & symptoms of relapsing fever.
Week 1= Latent period progressing to fever
- Specific antibody produced
- Fever improves
- Antigenic variation
Week 2= progressive bactermia leading to fever again
- Antibody produced
- Fever resides
- Antigenic varation
*Cycle continues
How is relapsing fever diagnosed?
- Microscopy- Giemsa stained blood smear
- Culture requires special media
- Serological and molecular techniques can be used to confirm diagnosis
How is relapsing fever treated?
Tetracycleine or erythromycin
How is relapsing fever prevented?
Limit exposure to arthropod vectors
List the characteristics of Rickettsia.
- Very small gram (-) coccobacilli
- Obligate intracellular pathogens– facilitate their own uptake into endothelial cells, escape from phagosome into the cytoplasm–>lead to focal lysis of filopodia
- Transmitted via arthropod bite