1. Spread of pathological processes in the organism. Septicaemia, sepsis, bacteriaemia Flashcards
How does infectious agent spread?
AMONG animals and WITHIN one animal
What are defensive mechanisms of organism against infectious agent?
- physical barriers
- innate immunity
- adaptive immunity
Skin as barrier for infection
- cornifying squamous epithelium
- ## pH around 7
What kind of transcutan infections can infect the intact skin?
- Dermatophytosis (=ringworm, стригущий лишай) (fungi)
- Malassezia (genus of fungi)
What kind of infections infect skin through lesions?
- papilloma
- tetanus
- rabies !
Arthropod-born disease
- babesiosis
- Lyme-disease
- WNV (West Nile virus)
- African swine fever
What defensive mechanism does GIT have against infection?
- low pH (1-2)
- viscous membrane
- digestive enzymes
- MALT-system (mucosa-assosiated lymphoid tissue) (IgA)
What are predisposing factors for infection in GIT?
- higher pH in stomach
- imbalance of microflora (i.g. because of antibiotics)
- clostridial overgrowth
- decreased peristalsis
- lack of digestive enzymes, decreased bile production
- immunosupression
Examples of aerogen infection:
- Marek disease (viral neoplastic disease in chicken)
- fungal spores
Examples of oronasal, conjuctival infection:
- bird flu
- fowl cholera (Pasteurella multocida)
Examples of urogenital infection:
- FLUTD (feline lower urinary tract disease), cystitis, pyometra
- dourine (Trypanosoma equiperdum), bruccelosis, AIDS
Examples of transplacental or intrauterine infection:
- BVD (bovine viral diarrhea)
- PRRSV (porcine reproductive and respiratory virus)
Examples of ovogen infection:
- Salmonella
What does iatrogenic infection mean?
relating to illness caused by medical examination or treatment
Examples of iatrogenic infection:
- PCV2 (porcine circovirus 2)
- EBL (enzootic bovine leukosis)
Factors affecting spread of pathogens and the disease
- Infectivity
- Pathogenicity
- Virulence
- Host specificity (PRRSV, Aujeszky disease (or pseudorabies, caused by herpes virus)
- Invasivity (tetanus, anthrax, FIPV!! (feline infectious peritonitis)
- Immunological function of the host
- Contagiousness (ability to spread) rabies, FMD (foot amd mouth disease)
– Temperature (CHV (canine herpesvirus), rhinoviruses)
– Humidity, other environmental factors
Infectivity vs pathogenicity vs virulence
Infectivity - ability to infect. Some pathogens can infect but not to cause the disease
Pathogenicity - potential ability to cause the disease
Virulence - severity of disease, degree of harm caused to host
Sequence of spread of the pathogen in the organism
Pathogen in the organism -›
Portal of entry -›
Primary processes -›
Metastasis
Metastasis is the name of the process or secondary lesion?
BOTH!
Metastasis - lesion identical to the primary one
Can be active process - migrating parasites
What are the types of metastasis by distance?
- local (direct spread to surrounding areas)
- regional (via lymphatic circulation to regional lymph nodes)
- distant (to distant organs)
What are the types of distant metastasis?
- lymphogen
- haematogen
- intracanicular (ascending, descending)
What is the outcome of metastasis?
Generalization
Types of generalization
- Bacteriaemia (low number of bacteria, only temporarily)
- Septicaemia (lots of bacteria for prolonged time)
- Pyaemia (pus gets into the circulation)
- Viraemia (free or cell associated)
Septicemia
pyogen bacteria -› sepsis
rottening bacteria -› sapraemia
SIRS
Systemic inflammatory response syndrome
Results of SIRS:
High TNF-alpha : DIC (disseminated intravascular coagulation)
- activation of 12 coagulation factor (intrinsic coagulation pathway)
- tissue factor expression on endothelial cells (extrinsic coagulation pathway)
- decrease of TFPI (tissue factor pathway inhibitor) and thrombomodulin levels
Liver damage -› decreased GNG
High NO levels: vasodilation - decreased blood pressure
SEPTIC SHOCK
Pathology of septicaemia
- Incomplete rigor mortis
- Dark red blood, incomplete post mortem coagulation (fast putrefaction, and haemoglobin imbibition)
- Spleen enlargement (septic splenitis)
- Generalized enlarged lymph nodes
- Acute catarrhal (mucous membrane) inflammation in the GI tract
- Haemorrhages everywhere (mucous membranes, under the serous membranes, in the cortex
of the kidneys) - Cloudy swelling in the parenchymatous organs (liver,
kidneys, heart and skeletal muscle)
