بسم الله الرحمن الرحيم GENERA: TREPONEMA & BORREILIA Prof. Khalifa Sifaw Ghenghesh

  Unicellular helical or spiral rod- shaped spirochaetes.   Actively motile – –Flagella attached at each pole of the cell and wrap around the bacterial cell body – –Flagella are enclosed within the bacterial outer membrane

Treponema   Do not stain by Gram’s method   Pathogenic Treponema – –T. pallidum – –T. pertenue – –T. endemicum – –T. carateum – –Cannot be cultivated in laboraotry media – –Maintained by subculture in susceptible animals – –Differentiation of organisms is based primarily on clinical syndromes – –Micro-aerophilic

Treponema pallidum   Syphilis – –Acquired by sexual contact with infected person   Congenital Syphilis – –Infected mother to fetus in utero or during passage of neonates through infected canal (vertical transmission)

PATHOGENESIS   Untreated the disease may progress to Primary, Secondary, latent and Tertiary stages.   Primary syphilis – –Organism penetrates intact mucosae > lymphatics > disseminates via blood to any organ – –Multiplies at entry site > ~ 3 weeks > painless chancre (mainly on external genitalia). – –Chancre heals spontaneous in 3-6 weeks

  Secondary syphilis – –Appear 2-12 weeks – – Symptoms are highly variable but mainly involve the skin (macular or pustular lesion) – –Lesions are highly infectious and gradually resolve   Latent syphilis – –No clinical manifestations are seen but serological evidence of infection remains – –Individuals are not generally infectious but can transmit infection to the fetus during pregnancy – –Their blood can be infectious

  Tertiary syphilis – –May develop decades after primary syphilis – –A slowly progressive, destructive inflammatory disease > affects any organ   Neurosyphilis   Cardiovascular syphilis   Gummatous syphilis

Histopathology showing Treponema pallidum spirochetes. Modified Steiner silver stain.

Treponema pallidum darkfield preparation

Light microscope pictures showing tissue infected with the spirochete Treponema pallidum, the causative agent of syphilis.

Treponema organisms stained by fluorescent-tagged antibodies.

Treponema pertenue – –Yaws – –Rural population in subtropical countries – – Non-venereal, after contact of traumatized skin with exudate from early yaws lesion – –Primary yaws (3-5 weeks) > lesions on the legs >> papular lesions >> enlarge erode and heal spontaneously within 6 months > may erupt weeks or months later. – –Secondary lesions > bones (fingers, long bones and jaw) – –Late yaws > cutaneous plaques and ulcers and thickening of the skin on the palms and soles of the feet.   No neurological and cardiovascular damage – – No congenital yaws

Treponema endemicum – –Bejel (endemic syphilis) – –Non-venereal, affects mainly children rural populations in Africa, western Asia and Australia – –Direct person to person contact and by sharing contaminated eating and drinking utensils – –Initial lesion > oral – –Secondary lesions > oropharyngeal mucous patches, condyloma lata and periostitis – –Late lesion > gummata in the skin, nasopharynx and bones   No neurological and cardiovascular damage – – congenital bejel is rare

Treponema carateum   Pinta   Rural regions of Mexico, Central America and Colombia   Confined to the skin   Non-destructive lesion but cause disfigurement   Direct contact with infectious lesions resulting in depigmented lesions which are characteristic of late stages of pinta with no serious harm

LABORATORY DIGNOSIS   Direct Microscopy – –Specimen: fresh exudate from primary or secondary lesions – –Examine with dark-ground or phase contrast microscopy   Serological Tests - T. pallidum infection > 2 types of Abs – –Specific Abs against polypeptide Ags of the bacterium – –Non-specific Abs reacts with a non- treponemal Ag > Cardiolipin

1. Non-Specific Serological Test   The Venereal Disease Reference Laboratory (VDRL) Test - Mixture of Cardiolipin, cholestrol and licithin as Ag - IgM or IgG Ab in positive serum or CSF from neurosyphilis case causes a suspension of lipoidal Ag to flocculate > read by the eye - Used as a screening test > – –70% of primary and 99% of secondary syphilis cases are positive – –Negative in late syphilis - Quantitatively > diagnosis of congenital syphilis - To monitor the efficacy of antibiotic therapy

2. Tests for Specific Antibody i. Fluorescent treponemal Ab (FTA-Abs) test – –Indirect immunofluorescence assay – –T. pallidum = Ag – –Acetone-fixed treponemes incubated with heat- treated sera > bound Ab detected by fluorescin-labelled conjugate and UV microscopy – –Positive in 80% primary, 100% secondary and 95% late syphilis patients. – –Remain positive after treatment

ii. T. pallidum haemagglutination assay (TPHA) - RBCs coated with T. pallidum Ag - Specific Ab in test sera >> haemaggluination - Positive in 65% primary, 100% secondary and 95% late syphilis patients. -Remains positive for life iii. Other Antibody tests - Monoclonal ant-T. pallidum Abs > ELISA - Detects Ab response individual treponemal Ags - Rapid screening of large number of samples

TREATMENT   Primary and Secondary Syphilis – –Prolonged high dose of procaine penicillin – –Erythromycin, tetracycline or choramphenicol   Late Syphilis – –Aqueous benzylpenicillin

CONTROL   Treating index cases and any known contacts

Borrelia   Gram-negative   Cause Relapsing fevers   Transmitted by arthropod vectors   Characterized clinically by recurrent periods of fever and spirochaetaemia   Disease occur world-wide

Borrelia recurrentis   Cause epidemic or louse-borne Relapsing fever – – An obligate human pathogen – – Person-to-person transmission by the body louse Pediculus humanus

Other Borrelia   B. duttoni   B. hermsii   B. parkeri   B. turicatae   Cause endemic or thick-borne relapsing fever   Transmitted to humans by soft-bodied Ornithodorus ticks   Natural hosts – –Rodents and other small mammals

LABORATORY DIAGNOSIS   Specimen – –Peripheral blood   Thick or thin blood smears stained with Giemsa, acridine orange or other stains   Serological tests – –Not reliable (due to antigenic variation) and not widely available

TREATMENT AND CONTROL   Tetracycline, Erythromycin, chloramphenicol and penicillin   Prevention – –Avoidance or eradication of the insect vector – –Eradication of ticks from human dwellings using insecticides – –Louse-borne infection   Good personnel hygiene   If necessary >> delousing