42-Treponema, Borrelia and Leptospira Flashcards
What is the structure of a spirochete?
• Spirochetes are tightly coiled with pointed, straight ends. Three periplasmic flagella are at each end. The spirochetes are too thin to be seen with light microscopy, but they can be visualized by darkfield illumination or by staining with specific antitreponemal antibodies labeled with fluorescent dyes.
What is a treponemal test?
use T. Pallidum as the antigen and detect specific anti-T. Pallidum antibodies.
What is a nontreponemal test?
measure IgG and IgM antibodies developed against lipids released from damaged cells during the early stage of disease and present on the cell surface of treponemes. • The big difference is that nontreponemal tests are less sensitive than treponemal tests for average healthy people in primary and tertiary phase, but treponemal tests are unreliable in patients with AIDS, because they have a weak immune system.
B. recurrentis- diseases
Epidemic Relapsing Fever
B. recurrentis- clinical Sx
Recurrent episodes of fever and septicemia seperated by afebrile periods.
B. recurrintis- lab tests
Microscopy
B. recurrentis- epidemiology
Transmitted person to person with lice as the vector. Seen most commonly in crowded or unsanitary conditions (refugee camps)
B. recurrentis- pathogenesis
Antigenic Variation - change proteins on outer surface so that antibodies don’t recognize them. This causes relapses of infection.
B. burgdorferi- diseases
Lyme Borreliosis
B. burgorferi- clinical Sx
3 Stages: 1. Bulls Eye rash and flu like symptoms for 2-3 weeks. 2. Disseminated fatigue, migratory joint and muscle pain. 3. Chronic arthritis and encephalitis
B. burgdorferi- lab tests
Immunofluorescence and western blot
B. burgdorferi- epidemiology
Mainly in the northeastern US. The reservoir is deer and mice, and the vector is a tick. Tick bites deer, the bites human.
T. pallidum- diseases
Venereal Syphilis
T. pallidum- clinical Sx
3 Phases: Primary Phase - lesions (chancres) at site of infection and infiltration of PMNs and macrophages. Secondary Phase - prominent skin lesions dispersed over the entire body surface. Late Phase (Tertiary) - all tissues may be involved.
T. pallidum- lab tests
DFA microscopy if mucosal ulcers are observed. Serology is sensitive.
T. pallidum- epidemiology
Humans are the only host and its transmitted by sexual contact. Congenital Trasmission - during the first 8 years, if untreated, trasmission from mother to fetus can occur at any time
T. pallidum-pathogenesis
Lack species specific antigens on cell surface, so they are able to avoid the immune system. They resist phagocytosis, and are able to bid to fibronectin allowing direct interaction with host tissues.
T, carateum- disease
Pinta
T. carateum- clinical Sx
Small papules develop on the skin and persist for months to years before resolving
Leptospira- disease
Leptospirosis
Leptospira- clinical Sx
Most common form of disease is mild and has virus like symptoms. Systemic leptospirosis most commonly presents as aseptic meningitis. Most serious is Weil Syndrome is characterized by vascular callapse, thrombocytopenia, hemorrhage and hepatic and renal dysfunction
Leptospira- lab tests
Culture blood or CSF in the first 7-10 days of illness
Leptospira- epidemiology
Reservoirs are rodents, dogs, farm animals and wild animals with humans as the end-stage host. People are infected through exposure to water contaminated with urine from an infected animal or handling tissues from an infected animal. Disease is more common during warm months.
