GENUS BORRELIA Habitat Spirochete gram - Giemsa or Wright’s stain are best 15-20 axial filaments ferment glucose and other CHO slow growing microaerophile Habitat obligate parasites in a variety of vertebrate hosts pathogenic borreliae of animal are vectored by ticks other arthropods are short term vectors

DISEASES Relapsing fever Lyme disease

Lyme Disease : Transmitted by ticks (Ixodes spp.) aquired by larval stages of ticks feeding on small rodents and variety of small wild animal act as reservoir hosts does not undergo the antigenic changes of relapsing fever B. burgdorferi (predominant in North America) B. garinii B. alfzelli etc

Virulence factor Spirochaete are restricted to the mid gut Following ingestion of blood , they are found in salivary gland Following ingestion of blood by the ticks, a change occur in outer surface protein of borreliae (Osp) from OspA to OspC (essential for virulence)

Reservoir host Maintenance host Lyme disease Incidental host

PATHOGENESIS Infected larva tick on small rodents (reservoir hosts) Infected nymph Infected adult Large animals (maintenance hosts) Susceptible animals human, dog, horse

Susceptible animals human, dog, horse blood stream through out the body(multiply) localized at skin(rash) joints, brain, nerves, eyes, heart Lyme disease

Human : B. burgdorferi Lyme Disease (continue) * endemic area : -American south & farwest, Europe * deer, mice and other rodents serve as reservoir * B. burgdorferi isolated from urine of dog & cows as well as milk from infected cow (infrequent) Human : B. burgdorferi * skin lesion (erythema migrans) for wks and months * later by neural, cardiac, arthritic complication

Dog : (frequently) Horse & Cattle : * polyarthritis, fever, anorexia * lymphadenopathy, carditis * renal disease Horse & Cattle : * abortion in cattle * polyarthritis, ocular and neural involvement in horses * foal mortality

Lyme arthritis Tick paralysis

IMMUNITY humural immune appears essential for protection against B. burgdorferi infection most animals appear to self-immunize with no apparent clinical manifestation subsequent to exposure to the spirochetes

Relapsing fever ornithodorus spp. B. hermsii tick-borne (animal to human) ornithodorus spp. Feed for short periods of time borrelia are inoculate within minutes more relapse, more fatality B. recurrentis louse-borne (human to human) long febrile & afebrile interval longer incubation period

Relapse phenomenon Outer surface proteins of borrelia allows a new clone to avoid antibodies directed against the original infecting organism the patient clinically improves until the new clone multiplies sufficient to cause another relapse

PATHOGENESIS Enter the host Generalized infection after one week spirochaetemia Fever, headahe, muscle pain (4-10 days) Afebrile period (5-6 days) Absence of spirochaetemia 1 relapse (louse-borne),3 relapse (tick-borne)

Immunoavoidance mechanism of borrelia illustrating the antigenic variants infection

Animal Borrelioses : Borrelia anserina (Argas spp.) * fowl spirochetosis in chickens, turkeys, geese, ducks, pheasants, pigeons, canaries, some wild bird * fever depression anorexia * greenish diarrhea * paralysis and anemia * splenomegaly, widespread hemorrhage * enlarged liver contains necrotic foci

Borrelia theileri (cattle, sheep, horse) * mild febrile anemia

ISOLATION AND IDENTIFICATION 1. Demonstration of the agent in tissues and fluids (dark field, immunofluorescence microscopy) 2. ELISA (antibody detection) 3. PCR (tissue or fluid) 4. Culture is laborious from synovial fluid 5. Antibody in serum or other fluid (indirect IF test)

B. burgdorferi (dark field)

Pathogens : Species Hosts Specific Diseases B. anserina birds Avian borreliosis B. burgdorferi canine Canine borreliosis man Lyme disease B. theileri bovine bovine borreliosis equine equine borreliosis other species man tick-borne relapsing fever

Brachyspira/ Serpulina Leptospira Borrelia Brachyspira/ Serpulina found in aquatic environment systemic infection shed in urine liquid media 30 0C aerobic dark field, silver stain, IF transmitted by arthropod vector systemic infection culture from affected animal special media 30-35 0C microaerophilic dark field, IF Intestinal spirochaetes (pig) localize culture from affected intestine special blood media 42 0C anaerobic silver stain, faeces histopatho section, IF