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52 Cards in this Set
- Front
- Back
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Introduction to zoonoses
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Lecture 1
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Define the term zoonosis
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Zoonoses = any disease or infection that is naturally transmissible from vertebrate animals to humans
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Outline the different ways that zoonotic diseases may be classified (6). What are some examples of each?
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1. Type of agent causing disease
- Viral, bacterial, fungal, parasitic, prion etc. - E.g. = 2. Based on reservoir host - Antrhopozoonoses (to humans from vertebrates) - E.g. = rabies and influenza - Zooanthropozoonoses (from humans to vertebrates) - E.g. = HIV and leprosy - Amphixenoses (maintained in both humans and vertebrates) - E.g. = Salmonella 3. Life cycle of infectious agent - Direct (ortho) zoonoses (can be maintained in a single vertebrate) - E.g. Salmonella, Brucella, Lepto - Cyclozoonoses (requires more than 1 vertebrate host but no intervertebrate host) - E.g. cestodes (hydatids) - Metazoonoses (transmitted biologically by intervertebrate vectors) - E.g. arbovirus (ross river, west nile), lyme disease and plague - Saprozoonoses (require a non-animal site to serve as a true reservoir or site for development) - E.g. Toxo, botulism, systemic fungae 4. Based on source of infection - Foodborne - E.g. = - Occupational - E.g. = - Environmental - E.g. = 5. Based on the route by which the zoonosis is acquired - Direct contact (e.g. dermatophytes) - Contact with animal products (e.g. antrhax) - Contact with urine (e.g. lepto) - Faeco-oral route (e.g. salmonella) - Bites and scratches (e.g. rabies) - Via ectoparasites (e.g. lyme disease) - Ingestion of poor meat (e.g. toxoplasmosis) - Ingestion of milk (e.g. Mycobacterium bovis) - Respiratory (e.g. histoplasmosis) 6. Based on the species of animal or type of vet that deals with them - Companion animal (e.g. = - Production animal (e.g. = - Avian/wildlife/exotics (e.g. = |
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Who are the main people at risk of getting zoonotic diseases?
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When production animals are the source the people at risk are:
- Farmers, vets, shearers, abattoir workers etc. When companion animal are the source, the people at risk are: - Vets, pet owners, breeders People at risk - Young or old - Immunocompromised - Pregnant women - Lower socio-economic groups - Owners of unhealthy animals |
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What are the key concepts in this lectures?
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- A healthy animal is the best way to treat zoonotic disease and to prevent zoonotic disease
- You are legally responsible for warning your employees and clients about zoonotic diseases - Important for vets to be aware of the real risks but to help keep them in perspective |
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What is the incidence of zoonotic disease in Australia?
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83 zoonotic disease in Australia
More than 50% of human diseases are zoonotic |
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What kind off economic cost would zoonotic diseases have?
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- Visits to doctos
- Hospitalisation - Length of hospital stay - Meds - Income loss |
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What is our legal responsibility as vets?
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- You need to have a reasonable knowledge of these diseases
- You need to provide isolation of sick animals - You need to warn clients and employees |
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What is the impact of zoonotic diseases?
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- Depends on what country is involved (developed vs. underdeveloped
In underdeveloped countries, the diseases that cause the most issues - Brucellosis - Bovine TB - Q fever - Rift valley fever - Cysticercosis - Zoonotic trypanosomiasis Risk factors in underdeveloped countries - Enviro is conducive to transmission - Regular close contact b/w animals and people - Animals have access to human waste - Not much preventative health provision for animals - Inconsistent meat inspection - Poor food quality and storage for both - Presence of immunocompromising infections (e.g. HIV) |
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Skin Zoonoses
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Lecture 2
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What skin zoonoses are there?
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- Dermatophytes (fungi)
- Sporotrichosis (fungi) - Parapox (orf) - Scabies - CLM - Anthrax - Erysipeloid - MRSA - MRSP |
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Ringworm (dermatophytosis)
What is it? What are the different types of ringworm? What are the different generas? How is it transferred? Diagnosis? Treatment of localised and generalised? |
What
- It is an infection of human and animal epidermal tissues caused by dermatophytes (fungae). These fungae especially like keratin as a nutrient so they parasitise the stratum corneum of the skin 3 types that affect humans (according to host reservoir) - Zoophilic (animal parasites) - E.g = M. canis, T. verrucosum, T. mentagrophytes (also affect Hs) - Antropophilic (human parasite) - E.g. = T. rubrum (infects As also, but rarely) - Geophilic (soil inhabitants) - E.g. = M. gypseum (infectus Hs and As rarely) There are more than 40 species of dermatophytes belonging to 3 different genera 1. Microsporum 2. Trichophyton 3. Epidermophyton Sources - Could come from animals (zoophilic) e.g. dogs, cats, rodents, rabbits, cattle, horses, birds etc. - Could come from other children(anthropophilic) - Could come from the soil (geophilic) but rare Transmission 1. Direct (contact with lesions 2. Indirect (spores can survive for months in the enviro) 3. Person to person (rare for zoophilic or geophilic, but can get anthropophilic) Diagnosis 1. Culture (child's lesion) 2. Examine animals (look for lesions) - Wood's lamp (look for fluorescence) - 10% KOH (look for spores) - Culture hairs from periphery of lesions (Derm test media) - Biopsy lesion (histopath) Note, 30% of cats and 5% of dogs are carriers!! Confirm with toothbrush test (brush entire coat) and DTM Treatment of single lesion - Clip 6cm around lesion - Apply topical miconazole/econazole cream daily - Wash animal 1-2/week in malaseb Treatment of generalise lesions - Treat aggressively (topical and enviro) - Total body clip - Use shampoos and rinses - Can also use systemic treatment (itraconazole etc) - Treat until 2-3 -ve toothbrush tests 2 weeks apart - Treat enviro (bedding, floors, furniture, vacuum) |
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Sporotrichosis
Organism? Source? Transmission? Clinical signs in animals and humans? Diagnosis? Treatment? Prognosis? |
Organism
- Sporothrix schenkii - Dimorphic fungus - Cigar shaped yeast form at 37degrees - Filamentous fungi at 25degrees - Rare in humans, found worldwide Source - Soil and cats with the disease Transmission - Contact with the organism in soil or a lesion (rose pickers disease) Clinical signs in animals - Fixed cutaneous form (skin nodules at site of inoculation... eventually ulcerate and drain) - Lymphocutaneous form (most common, fungi enters the lymphatics and causes problems) - Extracutaneous or disseminated infections (systemic, lymph nodes and organs affected, occurs in immunocompromised) Clinical signs in humans - Fixed cutaneous, lymphocutaneous, pulmonary and osteoarticular forms Diagnosis - Microscope examination - Culture of exudate - Biopsy specimen Treatment - Surgery (drain) - Drugs (Humans have K or Na iodide orally, animals have itraconazole, amphotericin B for disseminated infections) Prognosis - Poor for disseminated infections |
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Blastomycosis
What is it? What are the 3 different forms it presents in? In Aus? |
What
- Soil inhabiting yeast/fungus - Blastomyces dermatidis 3 clinical forms - Pulmonary - Disseminated - Cutaneous Exotic to Aus |
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Parapoxvirus (Orf)
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Lesions in humans
- A red papule appears at site of previous trauma - A large vesicle forms, surrounded by inflammed skin - Crust forms followed by a rolled edge ulcer 1-4cm in diameter - Heals after 4-6 weeks |
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Scabies
Organism Transmission Clinical signs Diagnosis |
Orgaism
- Sarcoptes species (mites) Transmission - Contact with infected animal of fomites - Mites burrow deep into skin (can go through clothing) Clinical signs - Skin lesions due to hypersensitivity to mite saliva and excreta - Pruritic (worse at night) Diagnosis - Skin scraping (demonstrate mites and eggs) |
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Ancylostoma species
Organism Lesions in humans Source Clinical signs Treatment |
Organism
- Hookworms Lesions in humans - Larva migrate cutaneously Source - Ova is passed in animal faeces - Mature in soil to larvae - Larvae penetrate skin Clinical signs - Intense pruritis and red papules at point of entry Treatment - Self limiting but can be treated with ivermectin |
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Leprosy
Organism |
Organism
- Mycobacterium leprae |
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Anthrax
Organism Source Cutaneous, pulmonary and intestinal forms |
Organism
- Bacillus anthracis Source - Acquired via exposure to infected animals and their products (wool, hides etc.) Cutaneous form (malignant carbuncle) - Most common - Skin lesion looks black - Respond well to therapy - Not fatal Pulmonary form (woolsorters disease) - Due to inhalation of spores - Rapidly fatal if untreated Intestinal form - Uncommon - Due to eating affected animals (undercooked meat) |
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Erysipeloid (diamond skin disease)
Organism Source Transmission Manifestation in humans |
Organism
- Erysipelothrix rhusiopathiae Source - Flesh and bone of dead pigs, fish and chickens and fish Transmission - Gains entry via broken skin Manifestation in humans - Skin lesions (self limiting) - Systemic (septicaemia, death from heart valve defects ... very rare) |
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MRSA and MRSP
What? Groups at risk? Transmission? Hosts? Diseases in humans? |
What
- Methicillin resistant staph aureus - Methicillin resistant staph pseudintermedius Groups at risk? - Nosocomial acquired (hospitals, nursing homes, surgery) - Community acquired (young, lower socioeconomic, sport people, injection drug use, military people, inmates, vets, pet owners, pig farmers) Transmission - Direct contact with infected wound or secretions - Indirect contact with contaminated surface (fomite) = more uncommon Hosts - MRSP is more common in animal hosts than people - MRSP is a known pathogen of dog bite wounds - MRSA is found in humans as well Disease in humans - S aureus causes skin and soft tissue infections (furunculosis, folliculitis, cellulitis) - More invasive strains associated with pneumonia and necrotising fascilitis - Spesis |
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Rabies
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Lecture 3
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Rabies pathogenesis?
Including transmission and incubation period? |
Pathogenesis
- Animal is inoculated via bite or scratch - Virus replicates in peripheral tissues - Moves to the CNS - Disseminates in CNS and replicates in brain resulting in clinical signs - Centrifugal spread to various organs, especially salivary glands Other transmission pathways (rare) - Aerosol - Ingestion - Tissue transplant Incubation period - Long (weeks to months) - Depends on bite location |
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Organism?
Who is susceptible? |
Organism
- Fam = rhabdoviridae - Genus = lyssavirus - 11 distinct species - Enveloped, single stranded negative sense RNA virus Who is susceptible - All mammals - but varies with genotypes and strains - Reservoir species are more specific |
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Clinical signs?
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Clinical signs (furious rabies)
- Restless - Hyperaesthetic - Aggressive - Lose fear - Hypersalivation - Change in vocalisation - Progressive neuro dysfunction Clinical signs (dumb form) - Paralysis - Dull - Coma - Death |
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Diagnosis?
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Diagnosis
- Anamnesis (history) and clinical signs - Pre mortem diagnosis is unreliable - PCR neck skin biopsy or saliva, Ab detection in CSF or blood) - Lab confirmation: Negri bodies (histo) Mouse inoculation test (laborious, slow) Direct immunofluorescence Ab test (GOLD STANDARD Direct immunohistochem Ab test (pretty good too, costs much less than the gold standard too) RT-PCR (enables genotyping for epi investigations) |
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Control and treatment?
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Control
- Vaccinate pets (1st vaccine at 3mo, regular booster) - Post exposure (immediate washing with soap, Ig and vaccination, only available for humans and expensive, not really great for developing countries) Treatment - Not available |
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What are some take home messages about rabies?
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- Rabies still causes 1 death every 10 mins worldwide (children are overrepresented)
- Rabies is preventable and can be eradicated effectively by addressing the reservoir population (dogs and wildlife) - Even though not present in Aus, don't ignore this is possible differential. |
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Viral disease associated with bats (lyssavirus and hendra virus)
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Lecture 4
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Australian bat lyssavirus
Organism? Source? |
Organism
- Fam = rhabdoviridae - Genus = lyssavirus type 7 - Closely related to rabies - This IS in Aus - Virus can lasts 24hrs in saliva (but less when unprotected from elements) - Killed by heat, sunlight, soap and most disinfectants Source - Flying foxes (fruit bats) and insectivorous bats (micro bats) |
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What do sick bats look like?
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- Change in behaviour and mobility
- Paralysed and weak - Unable to fly - Aggressive - Vocalisation changes |
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Transmission?
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- Bites or scratches or exposure to bat saliva via MM
- Virus is present in saliva and neural tissues but nothing else |
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Lyssavirus in humans
Clinical signs ? Incubation period ? Diagnosis? |
Clinical signs
- Severe, diffuse encephalitis - death Incubation period - Few days to several years Diagnosis - Serology - PCR |
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Is it present in other species (horses)?
Clinical signs? DDx? |
Yes - we have seen it in horses.
Clinical signs - Off colour, dull - Mildly ataxic - Severe nervous signs such as seizures, swallowing problems, movement abnormalities, recumbency DDx - Hendra!! - West nile virus - Herpes |
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Prevention in humans?
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- Pre and post exposure vaccine available
- Pre is recommended for anyone handling bats Anyone scratched or bitten should: - Immediately wash hands with soap and water for at least 5mins - Contact local doctor (get post vaccine) - Bat should be submitted for testing NOTE: only vaccinated ppl with titres >0.5 IU/ml wearing appropriate PPE and who have been trained to deal with bats should ever handle them. PPE includes - Gloves - Long sleeves - Eyewear or face shield (protect MM) - Cuts covered with water resistant dressing - Hand washing after dealing with bat |
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Is lyssavirus present in dogs and cats?
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Has not been seen yet, but treat them the same as a human (clean bite wound, test bat for the virus, give rabies vaccine etc)
Monitor them for signs for up to 2yrs |
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Hendra virus
Organism? Source of infection? Transmission ? |
Organism
- Fam = paramyxoviridae - Genus = henipavirus Source of infection - Flying foxes = natural reservoir - Found in blood, urine, saliva, faeces, placental material, aborted foetuses and birthing fluids Transmission - Horses become infected via contact with pasture and feed contaminations - Horse to horse transmission has been seen too (direct contact or via fomites) Experimental clinical disease has been seen in other animals (e.g. cats), but other animals don't get clinical disease (e.g. dogs) and develop Abs without clinical disease Human contact - Humans get it after direct contact with horses or PMs (exposure of MMs and broken skin to nasal and resp secretions, saliva, blood and urine) - Unknown if humans can get it directly from bats |
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Clinical signs in humans?
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Incubation period = 5-14days
Clinical signs vary from mild influenza like illness to fatal resp or neuro disease Influenza like illness - Dry cough - Sore throat - Fever - Headache - Lymphadenopathy - Generalised body aching - Vertigo Acute progressive encephalitis |
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Incubation period in horses?
Clinical signs in horses? DDx? |
Incubation period = 5-16days
Early sings - Depression - Pyrexia - Tachycardia - Discomfort or restlessness - Resp distress - Anorexia - Ataxia - Oedema - Copious yellow frothy fluid in trachea and nasal discharge - Neuro signs (muscle twitching, head tilt, circling, facial nerve paralysis) - Colic In summary, vasculitis of organ determines presenting signs DDx - African horse sickness - Plant poisoning (crofton weed, avocado) - Acute septicaemia - Pneumonia, bronchopneumonia - Herpes - West nile virus |
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Diagnosis
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- PCR (method of choice)
- Viral isolation - EM - Positive serum neutralising Ab titres (takes time) via ELISA or viral neutralisation test - Immunofluorescence on histo sections |
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Prevention?
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Vaccine
GOOD PPE AND BIOSECURITY |
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Treatment??
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Neutralising human monoclonal Ab targeting the viral glycoprotein has been developed
Has worked in a ferret model - closely resemble human |
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NIPAH VIRUS
Organism? Present in Aus? Source? Transmission? Clinical signs? Incubation period? Diagnosis? Prevention? |
Organism
- Fam = paramyxoviridae - Genus = henipavirus Not present in Aus Source - Old world fruit bats Transmission - Transmitted from humans to animals - Can also be transmitted from human to human Clinical signs - Severe disease in many animals (e.g. pigs) - In humans, it causes encephalitis or acute resp disease Incubation period = 4-45 days Diagnosis - Serum neutralisation - ELISA - PCR - Immunofluorescence assay - Viral isolation by cell culture Prevention - No treatment or vaccine available |
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Menangle Virus
organism? Notifiable disease? Source? Transmission? Clinical signs in humans? Diagnosis? Prevention? |
Organism
- Fam = paramyxo - Genus = Rubulavirus NOTIFIABLE DISEASE Source - Flying foxes Transmission - To humans from pigs after close association with infected pigs especially during necropsy or birth - Pigs have infection for 10-16 weeks - Sows may abort or have mummified autolysed piglets or be born with skeletal or NS defects Clinical signs in humans - Influenza like illness (fever, headache, weight loss) - Rash - Not fatal Diagnosis - serum neutralisation - viral isolation by cell culture Prevention - No treatment or vaccine - Use PPE - Avoid contact with flying foxes - Don't plant flower or fruit trees near piggeries |
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Animal Bites
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Lecture 5
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Who are the people at risk?
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1. Vets
2. Children 3. Sex (males more likely to be bitten by dogs, females more likely to be bitten by cats) |
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What breeds are more likely to bite?
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- Bull terriers/pit bulls
- German shepherds - Dobermans - Rottweilers - Blue heelers - Collies But very controversial... difficult to categorise many crossbreeds etc. Most dangerous breeds change as popularity waxes and wanes Look at the deed - not the breed |
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What are the most common sites for lesions?
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Family dogs
- Arm - Back - Face Strays - Leg - Arms Cats - Extremities Related to the age of person being bitten |
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If a bite wound becomes infected, what are the most common bacterial species involved?
Discuss Capnocytophaga canimorsus - Organism - Clinical signs - Treatment |
- Pasteurella is the most common (canis or multocida, depending on cat or dog bite)
- Srep - Staph (especially aureus and pseudintermedius) - Moraxella - Corynebacterium species - Neisseria species - Enterobacteriaceae (e.g. E. coli) - Bergeyella zoohelcum Anaerobes often present in mixed infections Capnocytophaga canimorsus - Gram -ve bacteria, fusiform shaped - Slow growing - Difficult to culture - Part of normal flora in dogs and cats mouths - Infection via bite and scratch or licking of open wounds Clinical signs - Mild flu like symptoms to septicaemia, sepsis, meningitis and DIC - Can be fatal - Low virulent organism, therefore most infections occur in immunocompromised patients Treatment = penicillin G (though watch out for resistance) |
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Diagnosis of dog bite wounds
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Diagnosis
- Overt clinical signs of local infection and rapid deterioration - Systemic signs - Not responding to antimicrobials - Immunocomrpomised Treatment - Do not self treat... - Early management (< 8hrs) - Remove FBs - Clean and irrigate with high pressure - Drain abscesses - Remove devitalised and necrotic tissue - Primary vs. delayed repaire |
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In summary...
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- Do not blame the breed, look at individual situations and judge accordingly
- Some people are more at risk - e.g. children. Clearly not just a dog problem - 2 sides to the story - It's generally a failure in communication - Animals bring so much joy into our lives, it would be a shame to cut them out simply because we could not navigate our way around this problem - Preventative strategies need to be aimed at dog behaviour and education |
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Advice to prevent bites:
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- Teach children basic safety around dogs and review regularly:
- Do not approach an unfamiliar dog. - Do not run from a dog and scream. - Remain motionless (e.g., "be still like a tree") when approached by an unfamiliar dog. - If knocked over by a dog, roll into a ball and lie still (e.g., "be still like a log"). - Do not play with a dog unless supervised by an adult. - Immediately report stray dogs or dogs displaying unusual behaviour to an adult. - Avoid direct eye contact with a dog. - Do not disturb a dog who is sleeping, eating, or caring for puppies. - Do not pet a dog without allowing it to see and sniff you first. - If bitten, immediately report the bite to an adult |
