MICRO: Zoonoses

Question 1

What are zoonoses? What % of infections are made up by these?

Answer 1

Diseases that pass between people and animals

More than 70% of emerging human infectious diseases come from animals

• Examples of new emerging infectious diseases
  
  • VHF (viral haemorrhagic fevers)
  • Respiratory diseases (MERS)
  • Novel influenza viruses (pH1N1)

Question 2

How are zoonoses transmitted?

Answer 2

• Everyday contact with animals – scratches and bites*
• By-products (faeces/urine) – contaminated soil, litter
• Foodstuffs – carcass processing, milk and milking, raw/undercooked meats

*NB: less traditional pets must be considered e.g. reptiles, rodents, chickens.

Question 3

What are the two levels of classifying zoonoses?

Answer 3

1. ​Farm/Wild vs Companion
2. UK vs Tropical

Farm/wild animals

• Cattle
• Poultry
• Goats
• Pigs

Companion animals

• Cats/dogs (ticks, mice/rodents)
• Reptiles/amphibians
• Fish

Question 4

Give examples of zoonoses according to this classification.

Answer 4

NOTE: conditions that are native to the UK can also happen in other places, but it doesn’t tend to work the other way around (e.g. cases of Brucella likely to be due to a recent travel history and not likely to have been picked up in the UK)

Question 5

What is the most common cause of gastroenteritis and how is it transmitted?

Answer 5

Cause: Campylobacter

Reservoir = poultry, cattle

Transmission = contaminated food; often, cross-contamination.

Question 6

What are the clinical features of campylobacter infection? How is it investigated and managed?

Answer 6

• Investigations
  
  • Stool culture
• Management
  
  • Supportive

Question 7

Which strains of salmonella infect humans? What is its reservoir?

Answer 7

There are >200 strains of salmonella but only typhi and parathyphi can infect humans

Reservoir: poultry, reptiles/amphibians

Question 8

How is salmonella transmitted? What are its clinical features?

Answer 8

Transmission:

• Contaminated food
• Poor hand hygiene

Clinical presentation

• Diarrhoea
• Vomiting
• Fever

Question 9

How is salmonella investigated? What is the management?

Answer 9

Investigations

• Stool culture

Management

• Supportive
• Ciprofloxacin or Azithromycin

Question 10

Which zoonotic infection is a curved, gram-ve rod and has a reservoir of kittens >cats?

Answer 10

Bartonella henselae

Transmitted by scratches, bites, licks of open wounds, fleas.

Question 11

What diseases are caused by bartonella henselae? Which patients are affected by each?

Answer 11

• Cat Scratch Disease - affects immunocompetent and can present similarly to TB/lymphoma
• Bacillary angiomatosis - affects immunocompromised i.e. HIV

Question 12

What are the clinical features of cat scratch disease?

Answer 12

Presentation

• Macule at site of inoculation
• Becomes pustular
• Regional adenopathy
• Systemic symptoms (fever, night sweats, weight loss) i.e. like TB/lymphoma

Question 13

What are the clinical features of bacillary angiomatosis?

Answer 13

CAN BE FATAL AT PRESENTATION

• Skin papules
• Disseminated multi-organ and vasculature involvement
• Leads to bursting of blood vessels in various organs and tissues –> can cause long term sequelae

Question 14

What investigations would you do for cat scratch disease vs bacillary angiomatosis? What is the management of each? (NB: don’t need to learn managements in this lecture)

Answer 14

CSD:

• Ix: serology
• Mx: erythromycin, doxycycline

BA:

• Ix: histopathology. serology
• Mx: erythromycin, doxycycline, rifampicin.

Question 15

What is the reservoir of toxoplasmosis and how is it transmitted?

Answer 15

Reservoir = cats, sheep

Transmission:

• Infected meat
• Faecal contamination
• NB: Toxoplasmosis actually affects mice cognition and participation in risky activities which makes them more likely to be caught by a cat and ingested so that the life cycle can complete. Cats can then pass it onto humans.*
• Toxoplasmosis is actually present disproportionately more in those with schizophrenia so perhaps it may be linked to its development. This is especially dangerous in pregnant women as it can affect the foetus,*

Question 16

What is the clinical presentation of toxoplasmosis?

Answer 16

Clinical presentation:

• Fever + adenopathy
• Still-birth
• Progressive
  
  • visual loss
  • hearing loss
  • motor loss
  • cognitive loss
• Seizures
• Neuropathies (immunocompromised)

Question 17

What are the investigations and management of toxocplasmosis in pregnancy?

Answer 17

• Serology - Sabin Feldman Dye test (serum incubated with methylene blue dye to stain blue if no anti-toxo antibodies are present and so toxo remains intact)
• Toxoplasmosis PCR +ve in mother, -ve in baby –> Spiramycin (3-week course, 2-3g/day)
  
  • I.E. no vertical transmission
  • Spiramycin prevents vertical transmission
• Toxoplasmosis PCR +ve in mother, +ve in baby–> Pyrimethamine + Sulfadiazine
  
  • Treat baby for up to 1 year after delivery (if no termination)
  • Adjunct: Prednisolone

Question 18

What zoonotic infections are transmitted through unpasterurised milk? What are other transmission types and what is the reservoir for this?

Answer 18

Brucella burgdorferi

Reservoir = cattle, goats

Transmission:

• Unpasteurised milk/cheese
• Mucosal splash
• Undercooked meat
• Aerosolization/inhalation

Question 19

How does Brucellosis present?

Answer 19

Presentation:

• FLAWS (over a period of months)
• Back pain
• Orchitis (may lodge in testes)
• Focal abscesses (psoas, liver, etc.)

Question 20

What investigations can be done for brucellosis? What is the management?

Answer 20

• 1^st: Blood/pus culture (in Castaneda medium) – must tell the lab that this is ?brucella
• 2^nd: Serology

Management: 6 weeks of

• Doxycycline; and
• Gentamycin or rifampicin

Question 21

What is the pathogen causing Q fever? What is its reservoir and mode of transmission?

Answer 21

Cause: Coxiella burnetti

Reservoir = cattle, goats, (sheep)

Transmission:

• Aerosolisation/inhalation of secretions, waste, or milk of infected animals
• Unpasteurised milk

NB: most of goat products in UK come from the Netherlands. Common practice used to be that goat faeces and urine were not cleaned up but rather hay was piled on top; when it started to smell windows/doors were opened and this created the ideal environment for Q fever and >100,000 cases were reported there.

Question 22

What is the clinical presentation of Q fever?

Answer 22

Clinical presentation:

• Fever
• ‘Flu-like’ illness
• Pneumonia
• Hepatitis
• Endocarditis
• Focal abscesses (para-vertebral/discitis, etc.)

Question 23

What investigations and management are used for Q fever?

Answer 23

Investigations:

• Serology

Management:

• Doxycycline
• (Hydroxychloroquine)

Question 24

What causes rabies? What are the reservoirs and modes of transmission?

Answer 24

Lyssa virus

Reservoir = dogs, cats, bats

Transmission:

• Bites, scratches
• Contact with infected fluid

Question 25

What is the clinical presentation of rabies?

Answer 25

* Seizures * Excessive salivation * Fever * Agitation * Confusion * Headache

Question 26

What investigations are done for rabies? What is the management?

Answer 26

Investigations: * Serology * Brain biopsy * (USA saliva PCR) Management: * Immunoglobulin (only given if direct exposure to saliva likely and no pre-exposure to vaccine) * Vaccine

Question 27

What are the pathogens causing rat bite fever? What is the reservoir and transmission?

Answer 27

**Streptobacillus moniliformis** or **Spirillum minus** **Reservoir** = rats **Transmission** = bites and contact with infected urine or droppings

Question 28

How does rat bite fever present?

Answer 28

* Presentation (comes on 2-10 days after bite): * **1^st**: fevers, **polyarthralgia**, maculopapular progressing to purpuric rash * **2^nd**: can progress to endocarditis ## Footnote *Looks like septic arthritis*

Question 29

How do you investigate for rat bite fever? What is the management?

Answer 29

Investigations: l*ooks like septic arthritis* * Joint fluid microscopy/culture * Blood culture Management * Penicillin

Question 30

What is Hantavirus pulmonary syndrome? How does it present?

Answer 30

Viral illness with a range of manifestations (resp/bleeding/renal) geographically. _Clinical features:_ * Fever * Myalgia * ‘Flu-like’ illness * Respiratory failure (USA) * Bleeding (SE Asia) * Renal failure (SE Asia)

Question 31

What are the reservoirs of hantavirus? How is it transmitted?

Answer 31

Reservoirs: * Deer mouse --\> Sin Nombre virus * White-footed mouse --\> Sin Nombre virus * Cotton rat --\> Black canal virus * Rice rat --\> Bayou virus Transmission * Contact with infected urine or droppings * Aerosolisation

Question 32

What is the name of Hantaviruses in these reservoirs? 1. Deer mouse 2. White-footed mouse 3. Cotton rat 4. Rice rat

Answer 32

1. Deer mouse --\> Sin Nombre virus 2. White-footed mouse --\> Sin Nombre virus 3. Cotton rat --\> Black canal virus 4. Rice rat --\> Bayou virus

Question 33

What investigations should be done for Hantavirus? What is the management?

Answer 33

Investigations * Serology * PCR Management * Supportive

Question 34

List 4 viruses causing haemorrhagic fever. and their reservoirs

Answer 34

1. Bats - Ebola 2. Bats - Marburg 3. Rats - Lassa 4. Ticks - Congo-Crimean haemorrhagic fever

Question 35

How are viral haemorrhagic fevers transmitted? What is the clinical presentation?

Answer 35

Transmitted by contact with fluids of those who are infected. **Clinical presentation**: * Fever * Myalgia * ‘Flu-like’ illness * Bleeding

Question 36

What investigations should be done for VHF? What is an important differential?

Answer 36

* Investigations * Serology * PCR * Management = supportive Differential = malaria

Question 37

History of zoonoses

Answer 37

Instead of pets ask about contact with animals Travel history is important - * Ask specifically where they have been and write it down * Ask about kind of accommodation * Ask about types of activities they did (e.g. trekking, sex)

Question 38

What are the main 3 investigations used in investigating zoonoses?

Answer 38

* Culture * Bloods * Pus * CSF * Stool * Serology (targeted or _save i.e. save and freeze for later_) * PCR

Question 39

A 35 year old patient with abdominal cramps and diarrhoea after a BBQ. What is the most likley cause? 1. Beef 2. Pork 3. Chicken 4. Unpasteurised cheese

Answer 39

Question 40

35yo patient presents with fever after a bat bite. What potential infection is the most concerning? 1. Spirillum minus 2. Hanta virus 3. Lassa virus 4. Rabies virus 5. Streptobacillus monilliformis

Answer 40

Question 41

35yo patient is suspected of having Brucella infection in their right psoas after drinking unpasteurised goats milk. What is the first investigation to obtain? 1. Blood culture 2. Psoas pus culture 3. Serology 4. Whole blood PCR 5. Psoas muscle histopathology

Answer 41

1

Question 42

35yo patient presents with fever of 38.8oC after return from 3 months in Rwanda, when they co-habited in a hut with a family and their livestock. How should the patient be managed? 1. Admit to bay 2. Transfer to HCID unit at Royal Free 3. Admit into side room 4. Discharge 5. Discharge to return to infectious diseases clinic in 3 days

Answer 42

Question 43

What is the difference between Lassa and Lyssa virus?

Answer 43

**Lyssa virus** - causes rabies **Lassa virus** - viral haemorrhagic fever virus originating from rats