Lecture 8- Activity of a pathogen 1 Flashcards
Pathogen
Microbe capable of causing disease
Infection
Microbe established on/in host, (doesn’t have to result in disease).
Colonisation
When another species comes and invades
-20% are colonised and therefore more likely to get diseases.
Endogenous infectious disease
Arise/ is cause by bacteria inside self
eg) UTI, appendicitis
Bulk of infectious diseases
Exogenous infectious disease
arises from elsewhere
eg) flu, zoonosis, environ, human transmission.
What a the risks for a non-infected, non-immune individual.
Immune senecescence (gradual deterioration of IS with age)
Risk behaviours
Other illness
Principle Pathogen
Causes disease in those w/ intact immune system
Opportunistic pathogen
Causes infection only when immune defenses are down. (illness/ underweight)
Primary pathogen
causes disease by direct interaction with host
eg) gonorrhea
settings in which infection can occur
Community accquired
Community onset
Hospital acquired
hospital onset
nosocomial
Prevention of Healthcare-associated infection
gloves/gowns decontamination of spills disposal of sharps/needles waste-management HAND HYGIENE
Transmission of infectious agents can be…
Direct: sexual transmission contact faecal-oral -droplet -airbourne
Indirect:vector borne (healthcare worker)
transfusion
airbourne
Structural Viral classification
- Nucleic Acid (+ or - )
- Capsid (viral protein shell)
- envelope (HIV is a - sense RNA retrovirus)
+ sense vs - sense
Positive-sense (5’ to 3’) viral RNA signifies that a particular viral RNA sequence may be directly translated into the desired viral proteins.
Negative-sense (3’ to 5’) viral RNA is complementary to the viral mRNA and thus must be converted to positive-sense RNA by an RNA polymerase prior to translation. Like DNA, this RNA cannot be translated into protein directly
Disease viral classification
Hepatitis: eg) HAV, HBV and HCV are not related BUT we put together as they all damage the LIVER cells.
Respiratory viruses
Transmission viral classification
Arbovirus- insect bourne
Enterovirus- faecal oral
Respiratory- droplets contact
What are viral symptoms often due to, why is this
Damaged cells, as virus incorperate themselves into cells and produce more of themselves as they are unable to fo themselves.
Tissue tropism is the cells and tissues of a host which support growth of a particular virus or bacteria. Give hepatitis and HIV examples
HIV glycoprotein 120»_space; Helper T cell CD4 molecule
Hepatitis surface ntigen»_space;> unknown hepatocyte receptor
Some ways to diagnose viral illness
clinical
visualisation
viral culture
Serology (blood study, meausure AB levels against viral antigens)
How to prevent viral infections
vaccinisation/ immunisation
avoidance
