Zoonotic infections Flashcards
what is the animal reservoir for brucella?
there are lots of different species (>8)
currently Brucella suis is associated with pigs
Brucella abortus used to be common in Australia, and associated with camels and cows
worldwide, it is most common associated with goats (Brucella melitensis)
what sort of fever pattern is associated with brucellosis?
classically it is a slowly occurring, insidious onset fever associated with heads and myalgias
is brucella associated with a chronic phase or is it purely single phase?
it can survive inside the vacuoles of phagocytic mononuclear cells
treatment regimens are associated with relapse in 5-10%!
relapse is not due to antibiotic resistance
treat with a similar regimen, because of this
what is the bug in Q fever?
what forms does it take?
what is the reservoir?
Coxiella burnettei
it is an obligate intracellular Gram neg coccobacillus
it can survive intracellularly, or as a spore
these are extremely fastidious
reservoir is kangaroos, bandicoors, rats
uses ticks to spread to feral mammals
humans injected from inhalation of aerosols of bodily fluids from infected animals
what are the clinical findings on acute Q fever? the pattern?
bloods?
imaging?
any chronic cases?
not everyone is symptomatic with the acute illness - about 40%
:There is an acute onset fever.
can range from mild to severe
often presents at PUO
can cause a hepatitis
can cause a CAP
can lead to chronic Q fever in about 4% of cases
what do the different phases mean in Q fever?
it refers to the immunoglobulin (antibody) development in this disease, but also relates to the fact that the antiGENs in Q fever change during the disease
it refers to IgG and IgM. So it’s not as easy as IgM=acute.
phase 1 is more suggestive of chronic disease (both IgM and IgG are checked)
phase 2 is acute
Just use serum PCR though - it will be positive during acute illness
based on the different “antigenic phases” in Q fever, what makes the serological diagnosis of chronic disease?
an elevated phase 1 complement fixation test (CFT) > 200
if this becomes positive then go on to do echo
or an elevated phase 1 IgG > 800
what is the treatment of Q fever?
doxycycline
sometimes we give plaquenil and doxycycline. This combination changes the pH in the phagosome, and increases the bug-killing of the doxy
what causes leptospirosis?
how do we get exposed to it?
Spirochetes are the cause.
they are excreted in the urine of many animals - there are 22 different serovars, and each is associated with a bunch of different hosts
it is seen on dark field microscopy
what is the pattern of illness in leptospirosis?
there are 2 stages
these are really important to know
stage 1: 3 - 7 days
myalgia, headache
abdo pain
vomiting
CONJUNCTIVAL SUFFUSION (dilatation of the corneal vessels without inflammatory componetns) Fever
Stage 2: 4-30 days
this is more of the immune response now, less about circulating bug
less fever meningitis uveitis rash renal failure PULMONARY HAEMORRHAGE
petechiae
how do we diagnosis lepto?
the first thing is to do an IgM for lepto
this has a lot of false positives, and can also be positive if there’s been a recent infection
Once the IgM is positive, then we need to do a microscopic agglutination test and this is able to identify the serovar
can you do any prophylaxis for lepto?
doxy
treatment is doxy/amp, or CTX
what is the chief route of infection into humans of Q fever?
this is coxiella burnetii
it comes from aerosolised body fluids of infected animals. It seems to occur in abattoir workers, farmers, truckers
basically anyone with close contact with farm animals, particular with infected farm animal blood (note: the blood is aerosolised)
Typical manifestations of the septicemic stage of anicteric leptospirosis include the following
EXCEPT:
- Abrupt onset of fever, headache, and chills with rigors
- Aseptic meningitis
- Anorexia, nausea, vomiting, and abdominal pain
- Conjunctival suffusion
- Myalgia and muscle tenderness
aseptic meningitis is typical of the second phase of infection with lepto
A definitive diagnosis of leptospirosis is likely to be made on the basis of any of the following test results EXCEPT
- A fourfold or greater rise in titers of antibody in acute and convalescent sera (determined with use of the microscopic agglutination test)
- A positive ELISA or dot-ELISA test
- A positive culture of urine obtained in the first week of illness
- A positive culture of blood or CSF (the organism should be cultured in Fletcher medium or Ellinghausen, McCullough, Johnson, and Harris medium and incubated at 28-30oC for 6 weeks
the answer is #3.
blood cultures can be done in the first week, but the urine is only useful after this time, during the immune phase
