MEDI7305 Lecture Notes - Lecture 10: Serotype, Meningococcal Disease, Leptospira
M4b - Zoonoses & Tropical Diseases in Rural Setting
Animal zoonoses
Q fever Coxiella burnetii
Average cases/yr in QLD - average 174 cases per yr in QLD (2009-2013)
Cases as % Aus cases - 50% total Australian cases
Notifiable disease - YES
At risk groups - occupational, travel, contact
Farmers (cattle, sheep, goats, dairy), shearers, abattoir workers, meat
inspectors
Vets/ nurses/ students, animal transport workers, animal handlers,
researchers working with pregnant livestock, anyone within few km of birthing calves/
lambs/ kids, anyone within few km of abattoir, anyone handling clothing/ rubbish
contaminated with birthing fluids
Chronic Q fever - immunosuppressed, pre-existing valvular disease
Geography of infection - all throughout QLD (also rest of Aus and world except NZ)
Transmission - source, contact, vector, route
Source - cattle, sheep, goats (also feral kangaroos, tick faeces on hides/ in
wool)
Contact - humans
Route - inhalation of aerosolised organism (up to several km) from placental
tissue, amniotic fluid, urine, faeces OR ingestion of unpasteurised milk
o1g placenta carries a billion organism, and inhalation of 1 single
organism is enough to initiate infection
oOrganisms will survive harsh environmental conditions for over a
year
oMilk pasteurisation kills organism (note: oral ingestion is not
deemed a method of transmission)
Incubation - usually 2-3wks (ranges from 4 days - 6wks)
Symptoms + signs
50% asymptomatic
Usually 5-14 day febrile influenza-like illness - fever, retrobulbar headache,
myalgia, chills, fatigue, sweats, +/- non-specific rash
10% pneumonitis (XR changes, dry cough, dyspnoea, pleuritic chest pain)
Rarely clinical hepatitis (although elevated transaminases are common)
10-20% post-Q fever fatigue lasting 6mths
1-5% chronic Q fever with endocarditis
Investigations
FBC - WCC normal 70%, elevated 30%, thrombocytopenia 25%
LFTs - mildly elevated transaminases 2-10x in 70-85%
CXR - non-specific changes
Diagnostic tests
C Burnetii PCR - +ve PCR test in first few days of illness, perhaps first 2wks
Q fever serology
oAcute Q fever - Ab to phase 2 Ag
oChronic Q fever - Ab to hase 1 Ag
oAt fever onset, serology is usually -ve (hence requires re-testing)
oLook for 4x rise in Ab titre on parallel tests (1-4wks apart) OR
documented seroconversion from IgG -ve to IgG +ve
Management
Acute Q fever
oAge 8+yo/ not pregnant - doxycycline 100mg bd for 2wks
oAge <8yo/ pregnant - azithromycin [B1] or clarithromycin [B3] or
sulfamethoxazole-trimethoprim [C]
Chronic Q fever - doxycycline + hydroxychloroquine (Plaquenil) for 18+mths
Complications & case fatality
find more resources at oneclass.com
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If infection during pregnancy - risk to foetus
Prevention (including vaccines, insect repellents, pasteurisation of milk)
Animal vaccine - NO
Human vaccine - YES
Pasteurisation of milk to kill organisms
Reduce transmission rate via …
Q fever vaccinations (see above)
Unless vaccinated, avoid high risk activities in - pregnant women,
immunocompromised, patients with heart valve abnormality
Animal contact
oStrict hygiene practices when handling animal hides, wool and straw
oWear PPE if handling pregnant animals or assisting at birthing
oAvoid handling placental tissue and amniotic fluid
oEnsure all placental tissues, birth tissues and contaminated litter are
burnt or buried
oWash hands and arms thoroughly with soapy water
Do not have animals birthing near people's homes & don't live within 1km
downwind of an abattoir or animal birthing site
Drink only pasteurised milk
Q-vax human vaccination
National Q fever program (2003 - 2006) gave free vaccinations to abattoir
workers, abattoir contractors, sheep shearers, sheep/ dairy/ beef cattle farmers or
employees, unpaid family members working on farms etc
Recommended vaccination groups
oAgricultural college staff and students (aged 15+yo) exposed to high-
risk animals
oVeterinarians, veterinary students, veterinary nurses
oAbattoir workers and contract workers in abattoirs (excluding pig
abattoirs), livestock transporters, sheep shearers, cattle/sheep/dairy farmers,
workers culling or processing kangaroos or camels, tanning and hide workers, goat
farmers, livestock saleyard workers, those handling animal products of conception
oWildlife and zoo workers in contact with at-risk animals (kangaroos,
bandicoots etc)
Q-vax (CSL) is a 0.5mL whole-cell killed vaccine containing egg protein
(licensed in Aus since 1989)
o15+yo are able to be vaccinated
oSingle vaccination, no boosters
oPre-vaccination requirements/ screening - no Q-vax previously,
informed consent, no severe egg allergy, -ve Ab test, -ve skin test
oScreening potential candidates via - history, skin test (0.1mL
intradermal), serology
Leptospirosis Leptospira organism
Complex nomenclature (serological vs genetic classification)
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
M4b - zoonoses & tropical diseases in rural setting. Average cases/yr in qld - average 174 cases per yr in qld (2009-2013) Cases as % aus cases - 50% total australian cases. At risk groups - occupational, travel, contact inspectors. Farmers (cattle, sheep, goats, dairy), shearers, abattoir workers, meat. Vets/ nurses/ students, animal transport workers, animal handlers, researchers working with pregnant livestock, anyone within few km of birthing calves/ lambs/ kids, anyone within few km of abattoir, anyone handling clothing/ rubbish contaminated with birthing fluids. Chronic q fever - immunosuppressed, pre-existing valvular disease. Geography of infection - all throughout qld (also rest of aus and world except nz) Source - cattle, sheep, goats (also feral kangaroos, tick faeces on hides/ in. Route - inhalation of aerosolised organism (up to several km) from placental wool) tissue, amniotic fluid, urine, faeces or ingestion of unpasteurised milk o.
