Lecture 2 Flashcards
How can coronavirus be controlled
–appropriate hygiene
–quarantine measures
What are the general concept ways to control disease spread
- Transmission-mechanisms & routes
* Methods to prevent transmission
What does transmission mean
Passing of an infectious disease from an infected host to other individuals which may or may not have already been infected. Usually refers to micro-organisms but includes parasites.
What are the means of transmission
–Direct contact–Aerosols–Vector mediated–Fomites
What are the routes of infection
Aiborne/droplets Mucosal Faecal-oral Sexually transmitted Opportunistic infections Injuries
What does fomite mean
Any inanimate object or substance capable of carrying infectious organisms and hence transferring them from one individual to another. Egtissues, clothing, furniture, soap, pet food bowls, drinking vessels, door handles, bed linen,cutlery,money, toys.
What does zoonosis mean
An infectious disease transmissible under natural conditions from vertebrate animals to humans. Eg. BSE, rabies, hendravirus, psittacosis.
What does Vector mean
Any living carrier that transmits an infectious agent from one host into another (usually insects, butcan be animals). EgFleas (plague), mosquitoes (malaria), bats (lyssavirus), snails (liver fluke). A vector usually is required for part of the pathogen/parasite’s developmental cycle.
What does Nosocomial infection mean
Infections which are a result of treatment in a hospital or a healthcare service unit. Infections are considered nosocomial if they first appear 48 hours or more after hospital admission or within 30 days after discharge. Eg Staph aureus, Legionnaire’s disease
what factors influence transmission
•Hygiene
•Presence of preventative measures (vaccines, drugs)
•Virulence (pathogenicity), chronic vsacute infection
•Pathogen factors:
–Variation (flu)
–Adaptation (antibiotic resistance)
–Stability in environment (spores)
•Host factors (age, immune status)
•Politics (Bovine spongiform encephalopathy, BSE)
What does probablity mean
Probabilityis a way of expressing knowledge or belief that an event will occur or has occurred.
What hygiene method reduce the transmission
- Hygiene needs to be appropriate for the situation
- Hand washing
- Plumbing, clean drinking water
- Storing food correctly (temp, locality)
- Separate waste from food
What does disinfection mean
Removing most pathogen on area.
means that you are reducing the microbial load on an object. A good disinfection procedure is aimed at specifically reducing the numbers of potentially pathogenic organisms.
What does sterilisation mean
removing all pathogen on area.
Sterilisation is absolute.It means that ALL of the microorganisms have either been removed or killed. A sterile object has NO viable microbial cells present.
How can you control disease vectors
- Reducing the population of vectors, or contact with vectors will effectively reduce disease
- Mosquitos-this remains the best way we have tocontrol malaria (spraying, reduce breeding areas, mosquito nets), heartworm in dogs
How do you reduce the rate of transmission
•Hygiene measures •Vector control •Vaccines •Selective breeding •Antibiotics •Reduce contact with infectious agent –Quarantine –Logical work practices
What are the examples for controlling disease vectors
- Rats-Plague
- Cattle ticks-Babesiosis
- Fruit bats-Lyssaviruses
What are the examples for controlling disease vectors
•Many are highly effective egparvovirus, distemper
•Smallpox and rinderpesthave been eliminated
•Scheme to eliminate polio underway
-measles - US
What are the example for controlling by selective breeding
- Tick resistant cattle
- Pest resistant crop plants
- Foot-rot resistant sheep
- Varroa resistant honey bees
What are the drawbacks of using antibiotics regularly
- Reducing number of pathogenic organisms will reduce transmission, but also leads to issue of residues in meat (withdrawal periods designed to prevent this)
- Also promotes resistance, egSalmonella become resistant.
What is Giardiasis
- Giardiasis is the most common cause of non-bacterial diarrhea worldwide.
- Giardia duodenalis(or lamblia) is a flagellated protozoan parasite.
Where does Giardiasis colonise and reproduce?
Small intestines
What are symptoms included for Giardiasis infection
- Symptoms include explosive diarrhea, excessive gas, severe abdominal pain, nausea and weight loss.
- Infects humans, cattle, pigs, dogs, sheep, cats, deer and beavers (~30% mortality in beef cattle calves)
How does Giardiasis transmit
-Water contaminated with animal or human feces
-Contaminated food
-Faecal-oral route (hygiene practices
Fomite
What is the life cycle of Giardiasis
Infect by ingestion of dormant cysts, then turns to active state of feeding and motility
-undergo asexual replication though longitudinal binary fission.
cysts and trophozoites found in feces. surviving outside the host to infect others