Transmission, Protists, Fungi Flashcards
How are infectious diseases classified?
By the pathogen that caused them
What are the examples of direct transmission?
-Person to person
-Airborne e.g. aerosols, droplets
-Exchange of bodily fluids
-Direct contact with animals or animal waste
What are the examples of indirect transmission?
-Vehicles e.g. food, water
-Vector e.g. malaria
-Surfaces, objects
What is physical contact?
Direct contact with an infected person e.g. chicken pox, common cold, measles
What is mother to child transmission?
An infection directly from the mother to an embryo, fetus or baby during pregnancy, childbirth or breastfeeding
e.g. HIV, syphilis, hepatitis B
What is zoonoses?
Physical contact with animals, diseases that animals can give to humans
e.g. rabies, lyme disease
What is a vector?
A living thing that carries a disease, it is a causing disease to a host
e.g. fleas, malaria
What is airborne?
Diseases spread through particles suspended in the air
e.g. measles, TB
What is vehicle/formite borne?
Disease spread from contaminated surfaces
e.g. tetanus, influenza, sepsis
What is food and welcome?
Disease spread through contaminated food and water sources or nutritional related
e.g. cholera, mad cow disease
What is bacteriophages?
Viruses that target bacterial cells
What is viral specificity?
Viruses often specific to a certain cell type due to the presence/absence of antigen markers
What is virus entry?
Inject only their DNA inside a host cell or those that inject animal cells can be wholly engulfed or have their lipid envelope fuse with the cell membrane
What is influenza’s mode of transmission?
-Targets ciliated epithelial cells of the respiratory tract
-Viruses inserts its RNA into cell, uses host cell machinery to produce new viral proteins an eventually new virus proteins
How is influenza spread?
-Droplets e.g. coughs, sneezes
-Direct contact with an infected person
-Contact with a contaminated surface or infected animal waste
-Animal to person (zoonotic)
What is the World Health Organisation (WHO)?
Monitors and reports on emerging and infectious diseases
What are the parts of bacteriophage?
-Capsome = repeating protein unit which makes up the protein coat
-Capsid = protein coat
-Nucleic acid = genetic material, double or single stranded
-Receptors/tail = viral proteins often involved in attachment to host cells
-Envelope = lipid derived from host cell membranes, not always present
What are the features of fungus?
-Single celled
-Cell walls made of chitnin and glycans
-Don’t photosynthesise
-Parasites or saprophytes (obtain food by absorbing dissolved organic matter)
What is the mode of infection for fungus?
-Spores are used for reproduction
-Many fungi grow as hyphae which are long thread like fillements emerging from the spore which penetrate the stomata or stem
How does hyphae work?
-Hyphae secret enzymes which digest the plant cells
-Nutrients are absorbed into the fungus
-Hyphae branch to form a mycellium that feeds and grows
-Often hidden in the stem/leaves of the plant
How does fungi affect crops?
-Mycelium grows into vascular tissue absorbing water and nutrients
-Absorbs nutrients from plant which reduces the yield
-Pustules break the plants epidermis making transpiration difficult
-Weakens the stem meaning plants are more likely to fall over
What are the malaria statistics?
-One of the worlds largest killers
-Infects up to 250 million and kills nearly 800,000 every year
-Child dies every 45 seconds due to malaria
-Children are most at risk as they don’t have natural immunity
How is malaria caused?
-5 species of single celled protozoan parasite
-Only females can pass on malaria as they need the additional protein from blood to develop their eggs
What is the life cycle of malaria?
-Extracellular and intracellular forms
-Sexual reproduction in mosquitoes
-Asexual reproduction in the liver cells and red blood cells of humans
What is an endemic disease?
-Diseases that are constantly present in a country or area
e.g. malaria, chickenpox, cold
-Becomes endemic when a disease’s presence becomes steady in a particular region or when it becomes predictable
Why is malaria still a problem?
-Increased resistance due to antimalarial drugs and insecticides
-Widespread poverty and inadequate availability of good health care systems
-Increased global air travel and migration can increase the spread
-Environmental changes caused by humans produces breeding sites
How is malaria being treated and controlled?
-Vectors control and change the biological control of mosquitoes
-Nets
-Sprays
-Reducing breeding sites
-Vaccines
-Reducing antimalarial drug resistance
What cells does the influenza virus target?
Airway epithelial cells
How is influenza transmitted?
-Cough
-Sneeze
-Infected surfaces
How can influenza spread be minimised?
-Isolate the infected person
-Vaccinate people
-Sanitise regularly including surfaces and objects
What is the pathogenic effect of influenza?
Causes the death of epithelial cells which causes a fever, sore throat, cough, body aches and fatigue
Why do we need a new influenza vaccine each year?
The antibodies from the previous vaccination may not be recognised as the virus has mutated
What is the exo-erythrocytic cycle of malaria? (human liver stage)
Sporozoites from the mosquitoes saliva asexually multiply for 7-28 days in the liver cells before differentiating into invasive merozoites which enter the bloodstream to initiate the erythrocytic phase
What is the erythrocytic cycle? (red blood cells stage)
5-13 days after the infection begins merozoites erupt into the bloodstream and invade erythrocytes where they undergo asexual replication
What is the sporogenic cycle? (mosquito stage)
The replication of the parasite while inside the mosquito
What is an insecticide treated net?
A type of meshed curtain that is draped over a bed or sleeping area to offer barrier protection against bites and stings from mosquitoes
What is indoor residual spraying?
Coating the walls and surfaces in the house with an effective residual insecticide where mosquito vectors are known to rest. It will kill adult mosquitoes that come into contact with the treated surfaces for month
What is breeding site reduction?
Involves removing standing water around your home to help reduce the mosquito population
What is the biological concept of mosquitoes?
The use of predatory fish which feed on mosquito larvae to control laval mosquitoes and manage larval habitats. Usually uses the freshwater fish Gambusia affinis (mosquito fish)
What is vaccine development?
Difficult to create due to the complexity of the protist and its lifecycle and their antigenic variation. There is also a lack of understanding between the interactions of the protist and the human immune system
What is the emergence of antimalarial drug resistance?
There is a genetic event which is creating a resistant mutant as well as the selection process where the survival advantage of the mutants are increasing
What is counterfeit drug market?
-The illegal production, distribution and sale of counterfeit drugs
-30% of malaria drugs in Africa are counterfeit or inferior quality
