RICKETTSIA

By Dr. Oduyebo

Rickettsiae
Obligate intracellular parasites
Small size
Arthropod borne
Transovarial transmission
Invade endothelial cells
Cause fever, rashes, vasculitis, eschar

Properties
Pleomorphic
Appear blue with Giemsa stain
DNA & RNA
Infect a wide range of animals
Grow in yolk sac of embryonated egg
Grow in cell culture, different parts
Cytoplasm -typhus group
Nucleus -spotted fever group
Cytoplasmic vacuole -C. burnetti

Resistant to sulphonamides
Sensitive to tetracycline, chloramphenicol
Quickly destroyed by heat
Quickly destroyed by drying except
C.burnetti, which forms spore-like structures
When in dried faeces of lice

Diagnosis
Clinical findings
fever, weakness, rashes, spleen & liver enlargement
Epidemiologic information
Serology agglutination, EIA, CFT, IF

Control
Vector control
Eliminate reservoirs
Pasteurization of milk
Protective clothing