Growth and environmental conditions: The hyphae fibres are specially adapted to invade tissues. Fungi generally rely on carbon dioxide produced by other organisms. Their versatility allows them to use a range of organic substances to grow including nitrate and ethanol.Transmission: Microsporum canis- direct and indirect contact.Aspergillus- direct contact through nose and sinuses.Effects on animal:Microsporum canis- bad coat conditions, scaling, itching reddened skin, hair loss, bleeding.Aspergillus- sneezing, nasal discharge, bleeding, swollen nose, reduced appetite.VirusesStructure and Function: Viruses have complex structures starting with the capsid head which contains RNA strands. The main body of the structure is the collar and sheath which connects to the base plate with the spikes and tail fibre. The main function is to infect and reproduce.Reproduction: A virus can only reproduce from inside a living cell and only attack specific cells, they need a host cell to survive and reproduce. Viruses are asexual meaning that they clone themselves to reproduce.Growth and environmental conditions: a virus will attack the host cells, and then infect more host cells and repeat the process until it has taken over.Transmission:Feline influenza- direct contact with infected cat.Canine parvovirus- direct oral or nasal contact with contaminated faeces.Effect on animal:Feline influenza- lethargy, depression, temperature, discharge, reduced appetite. Canine parvovirus- lethargy, depression, reduced appetite, sudden fever, vomiting, diarrhoea.ParasitesStructure and Function: Tapeworms are flat and segmented worms that consists of the head, which contains the suckers, the neck that leads to immature proglottids and finally, mature proglottids. Reproduction: Growth and environmental conditions: Transmission: Effect on animal:Structure and Function: fleaReproduction: Growth and environmental conditions: Transmission: Effect on animal: Part A.BacteriaStructure and Function: Bacteria have cell walls that contain the cytoplasm that makes up the majority of the cell. The cell also contains plasmid DNA as well as chromosomal DNA. Many bacteria cells also have flagellums which help with locomotion. Its main function is to reproduce and survive to carry on the species by infecting other hosts.Reproduction: Bacteria reproduce asexually by binary fission, beginning with the division of DNA and eventually splitting into two cellsGrowth and environmental conditions: They reproduce rapidly in the right conditions given that there is warmth, moisture and nutrients. Reproduction at body temperature (37°C) allows for the growth of pathogens harmful to health. Higher temperatures can induce faster growth.Transmission: Bordetella- highly contagious respiratory infection caused by aerosol droplets or fomites.Salmonella- ingestion of contaminated food.Effects on animal:Bordetella- coughing retching watery nasal discharge.Salmonella- diarrhoea, fever, vomiting, abdominal pain.FungiStructure and Function: The main body of fungi cells are made up of thin, branching fibres called hyphae. Individual fungus will have numerous hyphae, linked and joined to create a structure called mycelium. They have a complex cellular make up that contain a membrane-bound nucleus.Reproduction: Fungi reproduce via aerial spores. The spores are carried through the air or by rain and when they land, they germinate and reproduce. The spores grow into new organisms. Fungi can reproduce asexually and sexually.