Week 9 - Introduction to infectious diseases in animals Flashcards
What are the INFECTIOUS DISEASES -
MICROBIAL PATHOGENS
- Bacteria
- Fungi
- Algae
- Protists
- Viruses
What is the difference between Eukaryotes vs Prokaryotes
- Size
- Metabolism
- Cell organisation
- Replication
- Maintenance of shape
- Nucleic acid handling
- Ribosomal structure
- Genome
What are the Metabolic Diversity
• Bacteria can catabolise all naturally occurring organic compounds • Photoautotrophs • Chemoautotrophs • Photoheterotrophs • Chemoheterotrophs - all the pathogenic bacteria
Diffference between Viruses vs Bacteria
- Structural Unit
- Genome
- Replication
- Generation of Energy
- Size
Habitats of Pathogens
• Pathogenic bacteria and fungi originally
free-living
• Obligate parasites not able to survive
independently
• Saprophytes can live freely, don’t need
host
• All viruses obligate parasites, but not
necessarily in diseased animal
Microorganisms in the Environment
- Ubiquity of microorganisms complicates diagnosis
- Microorganisms in the environment can be mistaken for pathogens
- In some cases they are
- How can we determine their significance?
Differencee between Infection vs Disease
- Relatively few bacteria, fungi and viruses pathogenic
- Even most pathogens more frequently cause subclinical infections
- Infections (entry into the body) occur frequently
- Disease (loss of function) does not
What is the characteristics of bacteria etc in normal flora
- Always present
- Variation
- Role in health
- Protective role
- Source of opportunists
- Significance in diagnosis
Specific Sites for intrusion
- Mouth and Nasopharynx
- Stomach
- Duodenum, Jejunum and Ileum
- Large Intestine
- Trachea, Bronchi and Lungs
- Vulva and Prepuce
- Vagina
- Skin
- Mammary Gland
What is Koch’s Postulates
- Found in lesions
- Isolated in pure culture
- Experimental reproduction
- Recovered from experimental disease
How do you make a Microbiological Diagnosis
• If I detect an organism: – Is it from the animal? – Is it the one causing disease? – Is it the only one causing disease? • If I don’t detect an organism: – Is it because there wasn’t one there? – Is it because it didn’t survive the trip? – Did I look for the right one?
How to make the Correct Diagnosis
- Collect the sample from the right animal and the right place
- Treat the sample carefully and examine it as quickly as possible
- Interpret the results in the light of the situation you are presented with - common things occur commonly
What is the definition of a PARASITES
“Eukaryotic organisms that live in or on a host organism and cause harm to the host without immediately killing it.”
What are the major group causing disease
Features*
Endo- and ecto-parasites
Life cycles: direct; indirect
Infections: clinical/disease; subclinical
Names; host and organ system affected
Endemic; non-endemic (“exotic”)
Some are zoonotic*
What are PROTOZOA
What are they? : Unicellular organisms (“eukaryotic microbes”)
Biology : Free-living (millions); Parasitic (many!)
Significance : Socio-economic importance
Pathogenesis : Intraintestinal Extraintestinal
Reproduction : Intracellular Asexual, Extracellular Sexual
Life cycles : Direct Indirect
Size : 5-40 µm
Features : Vary, but characteristic for each ‘group’
Locomotion : Gliding, via flagella, cilia or pseudopodia, other
