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
What do you reduce transmission of Giardiasis
- Only drink water from reliable treatment facilities
- Do not drink from mountain streams without boiling or filtering the water.
- Wash hands after bathroom, touching animals, changing nappies, before preparing food.
- Treatment with drugs (egMetronidazole [Flagyl], quinocrine, furizolidone)
- Do not swim in recreational waters if you have Giardia
- Manage/contain contaminated cattle mature
What is food and mouth disease caused by
picornavirus Aphthae epizooticae
What does food and mouth disease infect
Infects cattle, sheep, goats, pigs, deer and other cloven-hoofed animals
What is the infectivity of foot and mouth disease
Highly infectious and highly virulent
Symptoms of foot and mouth disease
Causes high fevers, blisters in the mouth and on the feet, severe weight loss, milk reduction, high death rate in young animals
How does foot and mouth disease transmit
- Aerosols from animal to animal
- Fomites (farming equipment, vehicles, clothing, feed
- Sexual transmission
- Only rarely transmitted to humans
- Many epidemics have occurred world-wide
Is it fatel to animals
Rarely fatal in adults but causes permanent disability and reduction in growth and milk production.
What is the usual method to control transmission for foot and mouth disease
Quarantine and culling is the usually method to stop further transmission (local and international trade bans)
Why are vaccines effective temporarily
The ability of the virus to mutate means that vaccines are only effective temporarily
Many serotypes, with no cross-reactivityso vaccines are only strain-specific
What is Zika virus
- Zikavirus is a single-stranded RNA virus
- It circulates in Africa, the Americas, Asia and the Pacific
- Symptoms are mild and last for only a few days (fever, rash, conjunctivitis, muscle and joint pain, headache)
How does Zika virus transmit
- Zikavirusis transmitted primarily through the bite of an infected Aedesspecies mosquito
- A pregnant woman can pass the virus to her unborn baby
- A man can spread the virus to his sexual partners by sexual transmission
How do reduce transmission
- There is no vaccine and no medication for Zikavirus
- Transmission is effectively reduced by avoiding mosquito bites (clothing, mosquito nets and screens, insect repellent)
- Vector control
- Prevent sexual transmission
Who is in charge of the state level pest and disease control
Department of primary industries
Who is in charge of the national level pest and disease and pest control
department of agriculture
What are the systems for biosecurity
- Farm biosecurity
- Disinfection/sterilisation
- Laboratory safety standards
- Classification of organisms
- Classification of laboratories
How to maintain biosecurity if contact cannot be avoided
–Engineering/design solutions -prevent contact
–Work practices -work so as to avoid contact
–Protective devices -permit work, but prevent contact
–Personal protective equipment
What does ‘all in - all out’ mean
Any batch that enter a farm, will be quarantined
Where does ‘all in - all out’ usually operated
flock and herds for meat production
How do you choose the type of disinfectant
•Considerations
–type of microorganisms, numbers and presence of spores
–physical situation (surface type, suspension, etc.)
–contact available between disinfectant and microorganisms
–possible interaction between disinfectant and materials
–contact time allowable
–concentration
How do you eliminate envelope viruses
chlorine, iodine idophor, alcohol, oxidizing agents, phenol
What are the methods of sterilisation
•Heat –Steam (autoclaving) (usually 120oC, 20 or 30 min) –‘Flash’sterilisation –Dry heat (160oC or higher for 120 min or longer) •Low temperature methods –Ethylene Oxide –Hydrogen peroxide plasma –Peracetic acid –γ-irradiation •For prions (see later) –NaOH + heath –Sodium hypochloride + heath
What are the classification of organisms
Risk group 1, 2, 3 and 4. 1 with the lowest individual and community risk.
What are Risk group 1 organisms
–Agents have the lowest individual and community risk and include agents that rarely cause infection in healthy hosts.
–Examples include: laboratory strains of E. coli, S. cerevisiae, soil micro-organisms.
What are Risk group 2 organisms
–Agents may cause disease in healthy hosts, but are difficult to transmit, don’t usually cause serious or life-threatening illness and are readily treated or prevented.
–Examples include: nasty E. coli, Helicobacter pylori, Campylobacterspp, Plasmodiumspp, prions, HIV (infected blood only).
What are Risk group 3 organisms
–Agents are those that usually cause serious disease and may present a serious risk to laboratory workers.An RG3 agent may also present significant community risk if spread in the environment, but there are usually effective measures for treatment and/or prevention.
–Examples include: B. anthracis, hantavirus, yellow fever, HIV (cultures).
What are Risk group 4 organisms
–Agents are those that present significant individual and community risks and usually produces life-threatening disease, is readily transmissible and effective prevention and/or treatment are not usually available.
–Examples include: Ebola, Hendra and nipah viruses.
What are the classification of laboratories
- Laboratories are rated to a particular “Containment”level (PC1, PC2, PC3, PC4)
- Each Containment level has a set of regulations that must be met
- Protect personnel
- Protect environment (from accidental release ofpathogens or GMOs)
- Ensure experimental or diagnostic assays are notinvalidated due to contamination.
PC1-Physical containment 1. Meaning
–Suitable for work with microorganisms which are not known to cause disease in healthy adults i.e. Risk Group 1
PC2 certification lab
–Suitable for work with microorganisms which may cause animal, plant or human disease of moderate intensity i.e. Risk Group 2
PC3 certification lab
Suitable for work with microorganisms which may result in serious infection of animals, plants or humans i.e. Risk Group 3.
PC4 certification lab
Maximum containment for pathogens that are life-threatening, can cause epidemics and for which there is little or no treatment such as Ebola virus and Smallpox. i.eRisk Group 4.
What are PPE & protective equipment
- Gloves (select according to requirements)
- Safety glasses (AS/NZS 1337.6)
- Lab coat (back closing only)
- Closed shoes
- Class I safety cabinet/laminar flow: protects user by creating an air flow barrier
- Class II safety cabinet: protects product and user
What are Genetically modified organisms
- Overseen by Office of Gene Technology Regulator (OGTR)
- A genetically modified organism (GMO)is a plant, animal or other organism whose genetic material has been altered using genetic engineering techniques, generally known as recombinant DNA technology.
- Includes transgenic plants and animals which often have inserted DNA that originated in a different species.
What does Gene Technology Regulator (OGTR) regulate
OGTR regulates the Gene Technology Act 2000 ( + Gene Technology Amendment Act 2015), a national legislation covering the research , manufacture, production, commercial release of GMOs.
What must be done when dealing with waste in lab
–Storage-(double) contained, secure
–Transport-(double contained, labeled, contents identified)
–Decontamination (chemical disinfection, sterilised)
–Disposal of waste (incineration, land fill)
–Personnel must be trained, records must be kept.
How many classes of Biosafety cabinets are there
3 classes
What are the PF research animal facility for
•Driving principles: –animal welfare –staff safety –SPF health status –research outcomes
What are the Biosecurity in practice methods
–Work flows
–Quarantine
–Monitoring & testing
–Engineering controls
