Zoonoses

Question 1

Brucella

Answer 1

G -ve

MILK - unpasteurised milk, mucosal splash

Presents with UNDULANT FEVER, malaise, rigors, spinal tenderness, arthritis, hepatosplenomegaly, cryptorchidism

CAUSE OF INFECTIVE ENDOCARDITIS

Investigations: Anti-O-polysaccharide antibody (>1:160), WCC NORMAL.

Mx - Doxy + rifampicin, 6/52

Question 2

Rabies

Answer 2

LYSSA VIRUS (Rhabdovirus)
Spread by dogs and bats

Presents with prodromal symptoms followed by acute fatal encephalitis (hyperactive state)

Investigations

• Serum neutralisation tests
• Serum ELISA for specific IgM
• Brain biopsy - Immunofluorescence assay; NEGRI BODIES ARE PATHOGNOMIC

Mx - post exposure treatment can be given as long as patient has not been vaccinated pre-exposure
- 4 doses of rabies vaccine over 14 days + rabies Ig

Question 3

Plague

Answer 3

Yersinia pestis
G-ve lactose fermenter
Seen in US national parks still!

Bubonic plague - lymphadenopathy, dry gangrene

Tx - Doxycycline

Question 4

Leptospirosis

Answer 4

LEPTOSPIRA INTERROGANS

• SWIMMING/broken skin
• Exposure to rat wee
• High spiking temperatures
• Conjunctival haemorrhages
• Jaundice
• Haemolytic anaemia

Mx - amoxicillin/erythromycin

Question 5

Anthrax

Answer 5

• Bacillus anthracis
• Cutaneous lesions - painless round black lesions with rim of oedema
• Pulmonary disease - massive lymphadenopathy + mediastinal haemorrhage (known as Woolsorters disease)

Question 6

Lyme disease

Answer 6

• Borrelia burgdorferi
• Spread by ticks
• Initial skin lesion = erythema migrans (bulls eye)
• Persistent disease - focal neurology, neuropsychiatric disturbance
• Acrodermatitis chronic atrophicans - bluish skin lesions

Investigations

• Biopsy edge of erythema chronicum migrans
• ELISA for antibodies

Mx

• Doxycycline 3 weeks
• IV ceftriaxone if CNS involvement

Question 7

Q fever

Answer 7

Coxiella burnetti

• Cattle/sheep
• Presents like atypical pneumonia:

FEVER
DRY COUGH
PLEURAL EFFUSIONS
DIARRHOEA

NO RASH!!!!

Mx - doxy

Question 8

Rat bite fever

Answer 8

Streptobacillus monoliforms/Spirilus minus

• Fever
• Large joint polyarthralgia
• Maculopapular rash, develops to purpura
• Blood culture and joint fluid MC&S

Mx - penicillin

Question 9

Leishmaniasis

Answer 9

Protozoa

CUTANEOUS DISEASE
Skin ulcer at site of bite, heals after 1 year leaving depigmented scar

DIFFUSE CUTANEOUS DISEASE
Lots of NODULES with NO ULCERS

MUCOCUTAENOUS DISEASE
Starts as dermal lesion, then ulcers in mucous membranes

VISCERAL DISEASE - KALA-AZAR DISEASE

• Young malnourished children
• Abdominal disomfort, distension, weight loss
• Leishmania donovani invades RES causing hepatosplenomegaly and can get disfiguring rash (PKDL)

Question 10

Bartonella

Answer 10

Bartonella henselae = gram -ve rod
Can cause 2 diseases:

1. CAT SCRATCH DISEASE
   - macule forms at site of infection, develops into papule
   - Tx with erythromycin + doxycycline for 2/52
2. BACILLARY ANGIOMATOSIS
   - immunocompromised patients
   - Erythromycin + doxycycline + rifampicin

Question 11

Toxoplasmosis

Answer 11

• Found in cats and sheep
• Associated with brain changes

Presentation

• Fever
• Adenopathy
• Immunocompromised - seizures, neuropathy

Pregnancy complications - stillbirth, progressive visual, hearing and motor complications

Ix - serology

Mx

• Pregnant woman - Spiramycin
• Immunocompromised with head infection - pyrimethamine + sulfadiazine