Zoonoses

Question 1

Define zoonoses?

Answer 1

Animal infections that can cross the species barrier to infect humans, not infections like malaria that require humans for part of their life cycle.

Question 2

What are the major zoonoses?

Answer 2

Rabies
Brucellosis
Lyme’s Disease
Leptospirosis

Question 3

What organism causes rabies?

Answer 3

The Lyssavirus

Question 4

How is rabies transmitted and how does it affect you?

Answer 4

From bites of infected animals mainly dogs and bats.

It spreads via peripheral nerves to infect the CNS –> Acute encephalitits

Question 5

How does rabies present?

Answer 5

Non-specific symptoms of malaise, headache, lethargy, fever and eventually coma.
Also mania, overproduction of tears/saliva, hydrophobia, inability to swallow
Eventually most untreated patients will die of resp. failure

Question 6

How do you test for and treat rabies?

Answer 6

PCR saliva or CSF and confirm with a post-mortem brain biopsy (if they die)

Treat with PEP:

• Human Rabies Immunoglobulin (HRIG)
• 4 doses of rabies vaccine over 14 days

Question 7

What causes brucellosis?

Answer 7

Brucella

A small ggram-ve coccobacilli

Question 8

How do you get brucellosis?

Answer 8

Comes from cattle:

• Infected milk
• Handling carcasses
• Unpasteurized Dairy products
• During parturition

Question 9

How does brucellosis present?

Answer 9

Acute infection has non-specific symptoms, notably drenching sweat, high undulent fever, weakness and headaches.

Subacute (>1month) comes with fever and joint pain

A chronic infection has flu-like symptoms, malaise, depression, arthritis, endocarditis and epididymo-orchitis

So think of brucella whenever you see non-specific illness with exposure risk or a high undulent fever resistant to Abx

Question 10

How do we treat Brucellosis?

Answer 10

Long acting Doxycycline for 2-3months
+ Oral rifampicin or IM gentamicin for 1 wk

If they have CNS manifestations add 2 wks of cotrimoxazole

Question 11

What organisms cause leptospirosis

Answer 11

Certain spirochaetes.

Mostly L. Hardjo (Cattle) and L. Icterohaemorrhagica (rats)

Question 12

How do you get leptospirosis?

Answer 12

Today most people get it from water infected with animals urine, particularly swimming in lakes in africa

Question 13

How does leptospirosis present?

Answer 13

FEver - Myalgia - Headaches - Abdo Pain

Severe disease aka Weil’s Disease = triad of AKI/Jaundice/Bleeding

IT may also cause pulm haemorrhage

So think of it in fevered/fluey cattle farmers or people with exposure to water/rats

Question 14

How do you test for Leptospirosis?

Answer 14

ELISA serology
PCR
Culture (slow)

Question 15

How do we treat leptospirosis?

Answer 15

Doxycycline for mild
IV penicillin if severe

Dialysis for AKI and mechanical ventilation

Question 16

What causes Lyme’s Disease?

Answer 16

Borrellia Burgdorferi

A spirochaete found in wild deer and transmitted via ticks

Question 17

How does Acute Lyme’s present?

Answer 17

Erythema Migrans.

single or multiple red rings on the skin near the bite (3-90 days post infection)

Question 18

Lyme’s has many different late presentations, describe ACA?

Answer 18

Acrodermatitis Chronica Atroficans (ACA)

The extensor surfaces of the extremities (E.g. back of legs) turn bluish-red over months or years, often with a peripheral neuropathy

Question 19

Lyme’s has many different late presentations, describe a lymphocytoma?

Answer 19

A bluish solitary nodule that appears on the earlobes or areolas, mainly of kids.

Question 20

Lyme’s has many different late presentations, describe NB?

Answer 20

Neuroborrelliosis (NB)

Occurs 2-6 wks post bite
Triad of facial nerve palsy, radicular pain & lymphocytic meningitis

Question 21

Lyme’s has many different late presentations, can you name 5?

Answer 21

Acrodermatitis Chronica Atroficans (ACA)
Neuroborrelliosis (NB)
Lymphocytoma
Arthritis (large joint)
Cardiac Disorders e.g. perimyocarditis & heartblocks

Question 22

How do you diagnose Lyme’s Disease?

Answer 22

Clinically based on the presentation.

ELISA serology -> Immunoblot test to confirm

Question 23

How is Lyme’s Disease treated?

Answer 23

Oral Doxycycline OR Oral amoxicillin OR IV ceftriaxone

For 21 days but if they have arthritis or ACA up it to 4 wks.