Communicable diseases Flashcards
Module 4
What are pathogens?
They are organisms that cause disease.
What are the main categories a disease can be classified into?
Either communicable or non-communicable.
What is a communicable disease?
It is a disease caused by a pathogen which can be transmitted. - the pathogen is transmitted but not the disease. A disease is the effect of a pathogen.
What are the four types of pathogens?
Bacteria.
Virus.
Protoctista/Protist.
Fungi.
Is bacteria eukaryotic or prokaryotic?
Prokaryotic.
What are the features of a bacterial pathogen?
- They reproduce rapidly by the process of binary fission/mitosis.
- Cause damage to cells.
- Can release toxins/waste products that are toxic to the host cell.
- In plants they often are found in vascular tissue such as the xylem and phloem tissue.
- They are either gram positive or negative.
- They can be killed/treated with the use of antibiotics.
Are fungi eukaryotic or prokaryotic?
They are eukaryotic.
What are the characteristics of fungal pathogen?
- Generally not a major problem in animals but could have devastating effects on plants.
- Most fungi are multicellular but yeast are single-celled.
- Digestion occurs as an extra-cellular process.
- They are saprophytic meaning they feed off dead tissue/parasitic living tissue.
- They reproduce in millions on tiny diseases so they can spread huge distances.
Are viruses eukaryotic or prokaryotic?
Probably neither. They are very small 0.02 to 0.3μm and also generally non-living meaning that they require a host to grow and multiply/reproduce.
List some general characteristics of viruses.
- Their general structure consists of genetic material that is surrounded by a protein coat.
- Genetic material that is inserted in host DNA will hijack the biochemistry of the host cell.
- All natural viruses are pathogenic and have the ability to cause diesease in any other type including bacteria (bacteriophage).
- Some viruses can be modified to kill a pathogen in a process known as gene therapy.
Are protists eukaryotic or prokaryotic?
They are eukaryotic.
Give some characteristics of protists.
- They are varied and contain organisms that do not fit/classified into other groups.
- They are a small number which can be pathogenic in plants and/or animals.
- Protists that can cause disease are parasitic.
- Often required a vector to transfer them from one individual to another.
- They can directly transfer through substances such as polluted water.
What are the two modes of action of a pathogen on a host.
Direct damage of tissue - viruses/protists damage cells when they burst to release new pathogens. Protists also use the contents of the host cell during reproduction whilst fungi digest the cells/tissues.
Production of toxins - lead to damage of tissue. Most bacteria, some fungi will produce toxins as a by-product of their metabolism.
What are the two types of transmission?
Direct and indirect transmission.
State 3 types of direct transmission.
Direct contact, inoculation, ingestion.
State 3 types of indirect transmission.
Formites, droplet infection/airborne, vectors.
What is direct contact?
It is when pathogens are spread thorough actions such as kissing/ exchanging bodily fluids by actions such as sharing needles transmits pathogens such as meningitis/ STDs, whilst not maintaining proper hygiene could lead to diarrhoeal diseases. Other pathogens that can spread through direct contact are ring worm and athlete’s foot.
What is inoculation?
It is a break of the skin during sex, such as HIV, can also be transmitted through an animal bite such as rabies of through a puncture wound/sharing needles - septic aemia, HIV.
What is ingestion?
It is the consumption of taking in contaminated food or drink and the pathogen is transferred from the hand to v the mouth, e.g. it can lead to amoebic dysentry and diarrhoeal diseases.
What is formites?
This is where pathogens can be spread through inanimate objects such as bedding, clothing, cosmetics, machinery,etc. - e.g. Staphylococcus infection.
What is a droplet infection/airborne?
Droplet of saliva and mucus are expelled from an organism when they cough/sneeze/talk and can be breathe in/inhaled by a healthy person who becomes infected - e.g. influenza, tuberculosis.
What are vectors?
They are an organism that transmit the pathogen from one host to another and they are often always animals. An example of this malaria that is generally transmitted by a female Anopheles mosquito , rat fleas transmit the bulbonic plague and foxes/bats can transmit rabies. Water can also act as a vector and lead to the development of diarroheal diseases.
