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Flashcards in Zoonotic infections Deck (15):

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?


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?


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

CONJUNCTIVAL SUFFUSION (dilatation of the corneal vessels without inflammatory componetns)

Stage 2: 4-30 days

this is more of the immune response now, less about circulating bug

less fever
renal failure



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?


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

1. Abrupt onset of fever, headache, and chills with rigors
2. Aseptic meningitis
3. Anorexia, nausea, vomiting, and abdominal pain
4. Conjunctival suffusion
5. 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

1. A fourfold or greater rise in titers of antibody in acute and convalescent sera (determined with use of the microscopic agglutination test)
2. A positive ELISA or dot-ELISA test
3. A positive culture of urine obtained in the first week of illness
4. 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