R. prowazekii are red rods in the blue cytoplasm of the epithelial cell.
Dark field examination.
R. prowazekii are small black rods in cytoplasm of the epithelial cells and in the intracellular spaces.
Task 3.
Type specific Muzer’s serum for CFT is serum of the blood of the hyperimmunized animals. The preparation is used for diagnostic in complement fixation test for detection of Rickettsia prowazekii antigen.
Ricketsia Epidemic typhus Prowazekii erythrocyte diagnosticum for PHAT is erythrocytes bound with specific antigens. The preparation is used for diagnostic in PHAT for determination of specific antibody.
Coxiella burnetti dry antigen for CFT, Muzer’s dry antigens for CFT are the preparations that are used for diagnostic in complement fixation test for detection specific antibody.
Addition 1
Laboratory diagnostic of the ricketsia desiases
Group
Organism
Disease
Geographic distribution
Vector
Mammalian reservoir
Clinical features
Diagnostic test
Typhus group
Rickettsia prowazekii
Epidemic typhus, Brill-Zinsser disease
Worl wide
Louse
Humans
Fever, chills, myalgia, headache, rash
Serology
Rickettsia typhi
Endemic typhus, murine typhus
World wide
Flea
Rodents
Fever, myalgia, headache, rash; mider typhus then epidemic typhus
Serology
Other
Coxiella burnettii
Q fever
World wide
None (transmission by airborne fomites)
Sheep, cattle, goats, other.
Fever, fatigue, headache, pneumonia, can have major complications.
Positive CFT to phase I, II antigens.
Addition 2
What are morphological, physiological and tinctorial features of rickettsiae?
Pleomorphic, asporogenic, immobile short rods, 600x300nm size, or cocci, and they occur singly, in pairs, in short chains, or in filaments. With Giemsa’s stain, they are blue, with Macchiavello’s stain they appear red, in contrast with the blue-staining cytoplasm around them. They have cell wall gram-negative bacteria and microcapsules.
Distribution in nature: the bacteria from the family Rickettsiae
1. Isolation of rickettsia should be done only in reference laboratories for reasons of biosafety.
2. Rickettsiae lose their activity when they are stored at 0˚C, or incubated for a few hours at 36˚C.
3. Rickettsiae grow on different parts of the cell.
4. Rickettsiae are quickly destroyed by heat, drying, bacteriacidal chemicals.
Pathology
Rickettsia multiply in endothelial cells of small blood vessels and produce vasculitis. The cells become swollen and necrotic; there is thrombosis of the vessel, leading to rupture and necrosis. Vascular lesions are in the skin and other organs.
What are the pathogenic factors?
Pilli, endotoxin, some surface proteins, phospholipasae A2.
What are antigens of Rickettsiae?
They are lipopolisacharides, glycoproteins.
Epidemiology of epidemic typhus,
Brill-Zinsser disease.
The louse obtains the organism by biting infected human beings and transmits the agent by faecal excretion on the surface of the skin of another person. The scratching of the area of the bite allows rickettsiae excreted in the faeces to penetrate the skin.
Brill-Zinsser disease is a recrudescence of an old typhus infection. The rickettsiae can persist for many years in the lymph nodes of the individual without any symptoms being manifest.
What is epidemiology of endemic typhus?
Rickettsia typhi has reservation on the rat. The fleas can carry rickettsiae from fleas to human.
What is epidemiology of Q fever?
Coxiella burnettii is found in ticks, which transmit the agent to sheep, cattle, and goats. Worker in slaughter- houses and in the plants that process wool and cattle hides have contracted the disease because of handling infected animal tissues. C.burnetti is transmitted by the respiratory pathway rather than through the skin, sometimes through milk.
What are methods of endemic and endemic typhus microbiological diagnosis?
They are serological, biological, and microscopic examenation and cultivation in tissues cultures and fertilising eggs.
What are serological methods used for diagnostics of Rickettsiosis?
They are CFT, AT, PHAT, IFT, ELISA.
What are methods of Q fever microbiological diagnosis?
They are serological, biological, microscopic examination, cultivation in tissues cultures and fertilizing eggs and skin allergic test.
How C. burnettii is differentiated from other rickettsiae?
C. burnettii have structure lipopolisacharade (1 phase) or have none (2 phase) in cell wall.
What is treatment of Rickettsia diseases?
It is usung of the antibiotics.
What is prevention of epidemic typhus?
It is usung of the live epidemic typhus vaccines, killed epidemic typhus vaccines.
What is immunity?
It is cellular-humoral.
What is prevention of Q fever?
It is usung of the live Coxiella burnettii vaccines.
