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Spirochaetes (Other spirochaetes (Genus Borrelia (Tick-borne relapsing…
Spirochaetes
Other spirochaetes
Genus Leptospira
- Leptospirosis; world most common zoonotic disease
---2 stages: Septicaemic phase (fever, headache, conjunctival suffusion), Immune phase (rash, uvetis)
- Leptospira interrogans
- Bacteria can be carried by virtually any species of mammal (rats) --> excreted in urine
- Enter body through: skin abrasion, soggy skin, conjunctivae, resp tract mucous memb.
- Weil’s disease: more severe form of leptospirosis: liver (hepatitis), kidneys (oliguria), heart (myocarditis), brain (encephalitis), lungs (hemorrhagic syndrome)
Genus Spirillum
- Two forms of rat bite fever are caused by bacteria which live in rats’ mouths
- Spirillosis: Spirillum minus
- Streptobacillosis: Streptobacillus moniliformis (gram -ve rod)
Genus Borrelia
Tick-borne relapsing fever
- Americas, Africa, Middle east, China
- 7 species
- Transmitted by species of Ornithodorus ticks
- Symptoms: recurring fever, splenic enlargement, neurological complications (7th cranial nerve palsy, meningitis...)
Louse-borne relapsing fever
- Africa, South America, East Europe, Middle East, Russia, India, China
- Borrelia recurrentis
- transmitted by body louse, Pediculus humanus var corporis
- Clinical features: Worse than tick ones, high fever/delerium, headache/body pain, dyspnoea, hepatosplenomegaly, erythematous rash, bleeding into skin/membranes
Lyme disease
- Borrelia burgdorferi
- Northern hemisphere only
- Bacteria are injected into humans by Ixodes ticks
- Stages:
---1 and 2: erythema migrans, dissemination of the bacterium throughout the body may result in neuroborreliosis, arrhythmias and heart block.
---Late Lyme disease consists of arthritis of large joints
Genus Treponema - Non syphilis
Treponema endemicum
- Africa
- Bejel/endemic syphilis
- Begins in mouth --> skin, bone, cartilage
- disease similar to syphilis
Treponema carateum
- South America
- Affects only skin
- Scaly plaque-like lesions at site of infection --> grey, blue, purple, brown areas
- late stages, depigmented areas of skin develop
Treponema pertenue
- Yaws
- children <15 yrs
- primary lesion at site of inoculation (“mother”), followed by disseminated lesions (“daughters”)
- skin, cartilage, bone --> chronic disfigurement
Genus Treponema - syphilis
- Syphilis (STI) caused by Treponema pallidum
- Characteristics:
---Spiral morphology
---Obligate intracellular pathogen
---Cannot see on Gram stain.
General information
- Genital ulceration, it enhances the transmission of HIV
- Highest in many Indigenous and MSM
- 10m new cases, kills 1m babies each year.
Syphilis
- Venereal syphilis is acquired by direct skin or mucous membrane contact, usually anogenital with person of 1 or 2 syphilis.
- 1°, 2°, latent stage (decades), 3° syphilis.
2° Syphilis
- Begins with skin rash: rough red spots on palms or soles.
- Condyloma lata: broad-based gray or white warty lesions. Moist areas
- Mucous patches: ulcerated areas of mucosal breakdown
- Systemic features: fever, pharyngitis, muscle aches, joint aches, fatigue, lymphadenopathy, headache, weight loss, patchy hair loss.
- Aseptic meningitis, meningovascular syphilis. Chronic meningitis and arteritis of the small vessels of the leptomeninges, brain, and spinal cord, leading to infarctions
3° Syphilis
- 3 possible forms
- May develop in people who did not show 1° and 2°
Cardiovascular syphilis
- Small vessel vasculitis of blood vessels supplying the ascending aorta
- Aortic walls become weakened and dilated --> deformity of aortic valve.
- Aortic regurgitation can lead to heart failure
Gummatous syphilis
- Granulomatous lesions of skin, bones or viscera
Central nervous system syphilis (neurosyphilis)
- Form most commonly seen
- Progressive dementia, termed “general paresis of the insane”, or GPI. Due to frontal and temporoparietal lobe atrophy.
- Damage to the dorsal columns of the spinal cord results in “tabes dorsalis”(sensory ataxia leading to charcot's joint, lancinating pains, pupillary abnormalities (Argyll-Robertson pupils).
1° Syphilis
- Chancre, at the site of inoculation.
---Ulcer, painless, raised firm edges.
---contains replicating spirochaetes, infectious.
- Chancre on penis, labia, finger, tongue, perianal.
Congenital syphilis
- Passed to the foetus transplacentally
- Risk of transmission increases, but severity of infection decreases as pregnancy advances
- Risk also decreases with stage of syphilis.
- Sequelae: 40% stillborn, perinatal death, premature, LBW, congenital abnormalities.
- Sequelae in children: Deafness, corneal inflammation, saddle nose, abnormal teeth, bone abnormalities.