infectious diseases Flashcards
what is zoonosis
a infectious disease of animals that can be naturally transmitted to humans
describe the 3 disease phases
- infection
- incubation period- time from infection until symptoms appear
- disease- showing symptoms
- latent period- which is the time between infection and being infectius
- period of communnicability(infectious)- when infection can be passed to others, doesnt necessarily coincide with displaying symptoms
can some organisms go through a second latent period after infection when organism doesnt show any symptoms?
yes but can become active again such as herpes
list types of direct transmission - direct contact
- physical touch between infected host and susceptble host
-skin
sweat - tears
-vomit
-nasal secretions - blood
-saliva
-sexual fluids - urine
list some forms of direct transmission- close contact
- airborne droplets between an infected host and susceptible individuals due to close proximity < or = to 1.5m
- new host inhales the infected droplets
- coughing sneezing
list direct transmission- reservoir
- soil
- fomite- inanimate object that pathogen can survive on
list indirect transmission for a vector
- a living thing that transmitts
- mosquitos, fleas, ticks
as the insect becoes infected and hey feed on infected hosts the the disease is then transmitted when the insect bites a new host - malaria
list types of indirect transmission- airborne transmission
- spread when an infected person sneezes or coughs as droplets can handg in the air for a long time
- droplets can travel 1-2m and land on surfaces or objects including tables, telephones
such as covid
list indirect contact soilbourne/waterborne/vehicle transmission
- an inanimate object acts as an intermediary between the portal of exit form the reservoir and the portal of entry of the host
- pathogens can swim through water ( chytidomycosis)
- pathogen can be contaminated in the soil (crown gall)
- infectious soils can be carried on the soles of soles of tire treads
list the characteristics of bacteria
- unicellular
- prokaryotes - no membrane or membrane bound organelles
- plasmids(small loop of DNA)
- asexual reproduction(binary fission)
some have
- a flagelum fore movement (tail)
- slimy bacterial capsule to help stick to surfaces
how does bacteria cause disease?
- toxins which disrupt cell functioning or kills cells
- damage host tissue directly ( using it for nutrients or producing wastes)
- may produce an immune response so strong that it damages the hosts own cells
describe the invasion method for tuberculosis
enters through mucous membrane - mouth lungs nose
descrieb transmission of tuberculosis
direct from air (droplets) - cough, sneeze, talk from either humans or cows(zoonose)
descrieb the impact of tuberculosis on host (symptoms)
- coughing (chest pain)
- coughing up blood
- fever
- night sweats
- unintention weight loss
- headaches
- scarring of lung tissue
treat emant of tuberulosis
antibiotics- may take up to 6months
vaccination
invasion method for crown gall disease (agrobacterium)
- attracted to open wound by sugars/chemicals being released
- flagellated bacterium enters roots through open wound
- attaches to cells and plasmid DNA is inserted into plant DNA
transmission of crown gall disease
- indirect contact from soil reservoir
or from fomite(tools)
impact on host for crown gall disease
- galls (tumours) on roots and stems
- gall prevent the movement of water and nutrients
stunted growth
changes in gene expression
management strategies for crown gall disease
- disinfecting tools
- heat treat infected soil
- remove and burn infected plants
describe the 6 step life cycle of mycobacterium TB
- MTB enters the lungs
- MTB ingested by macrophage
- MTB multiply in white blood cells
- white blood cells burst releasing MTB to enter more WBC
- tubercle formes in lungs
- tubercle ruptures into lungs and MTB is coughed out
life cycle of crown gall disease
- bacteria enters roots from soil through wound
- bacteria transfer some DNA (plasmid)to plant cells
- bacteria reproduce in root forming gall
- gall detached and releases flaggelated bacteria in soil
process repeats going back to 1. as it swims to new host
what are the different types of antibiotics and how do they work
bactericidal - kills the bacterial cells
bacteriostatic- inhibits growth
works by
-1. repturing cell membrane
2. stop synthesis of new cell wall during cell division
3. inhibit enzymes essential for transcriptioin or translation
4. inhibit enzymes essential for metabolism
describe the characteristics of fungi
- Eukaryotic = has nucleus + membrane bound organelles
- cell wall of chitin
- reproduce by spores
- unicellular and multicellular
effects of fungi
mostly external causing inflamation and irritation of skin
invasion method of chytridiomycosis
- enters skin cells
transmission of chytridiomycosis
indirect- water bourne ( free swimming zoospores)
direct- contact between infected individuals
impact on host - chytridiomycosis
- thickening of skin affecting gas exchange and osmoregulation
- excessive shedding of skin
- lethargy
- legs spread outwards
- death
- sitting out in the open
- loss of rightening reflexes
describe the life cycle of chytridiomycosis
- single celled flagellated zoospore enters skin cell
- thallus forms
- new zoospore are produced in thalus as it matures (asexual)
4.zoospored released into water where they swim to find a new host
characteristics of viruses
- protein coat surrounding either DNA or RNA
- life cycle inside of cells making it hard for the immune systme to destroy and hard to treat with meds
- has a phospholipid envolope (derived from the hosts cells)
describe different invasion methods of viruses in general
- through a physical breach (cut in the skin)
- direct inoculation (mosquito)
- direct infection of the surface its self (mucus membrane)
describe the life cycle of a virus
- viral entry
- attaches to host cell membrane
- the hole forms in membrane
- the virus or its genetic contents are released into the host cell - viral replication
- viruses takes control of the host cells replicatino mechanism (DNA/RNA) - Viral shedding
- cell ruptures virus progeny are released to find new host cells
what is viral latency
- virus may remain dorment until conditions are favourable eg. cold sores
list the invasion method, transmission and impact on host for the virus influenza
invasion method- through mucus
transmission (indirect)- airborn (droplets)
impact on host
- fever/chills
- dry cough
-sore throat
- runny or stuffy nose
- headache
- tiredness/ extreme exhaustion
- muscle/joint pain