Australian Doctor 15th September 2023 AD 15th Sept Issue | Page 27

Figure 5 . Erythema migrans .

incorporate recombinant proteins expressed in vivo , but there is still the possibility of cross-reactivity with other spirochaetal and viral antigens , as well as autoantigens .

CDC / bit . ly / 3WI0ufh

Performing these tests in patients

with no risk factors for Lyme disease

, particularly in patients with

no international travel , is strongly

discouraged .

Culture of B . burgdorferi sl is

possible in reference laboratories ,

mainly from skin lesions , but it is

slow and essentially only performed

as a research tool . Molecular detection

of Borrelia sp . DNA in patient

specimens can also be undertaken .

However , this assay is only available

in reference laboratories , and

it can be difficult to obtain appropriate

samples from the patient ( as

is the case with cultures ). If DNA

from Borrelia sp . is detected in the

patient sample ( for example , by realtime

PCR ), then the RCPA recommends

that a conventional PCR , with

gel-electrophoresis of the amplified

DNA , should be undertaken . Any

DNA obtained should be sequenced

and undergo sequence comparison

with known Borrelia sp . 6

Internationally , there are many laboratory tests used , but they are not standardised . In the US , the

Figure 6 . Lyme disease arthritis .

Centers for Disease Control and Prevention recommends against their use . These include antigen capture assays in urine ; culture , immunofluorescence staining or cell sorting of cell wall – deficient or cystic forms of

DIFFERENTIAL DIAGNOSIS

DIFFERENTIAL diagnosis for classical

erythema migrans or multiple erythema migrans-like lesions — par-

The most common tick-borne infections in Australia are rickettsial infections and Q fever ( C . burnettii ). 7 These often have similar presentations to early Lyme disease ,

are usually mild . Q fever is often an asymptomatic infection but may present with fevers , headaches and myalgias . If left untreated , Q fever can cause chronic infection with

disease . 23 B . henselae is found in Australia in domestic and feral cats and can be transmitted to humans from the scratch of a cat , causing cat scratch disease . Signs and symptoms

B . burgdorferi sl ; lymphocyte trans-

ticularly in those who have not sus-

with fever , headaches and malaise .

similar manifestations to Lyme car-

of B . henselae infection may include

formation tests ; quantitative CD57

tained a bite from an Ixodes sp . tick

Rickettsial infections often cause

ditis or neuroborreliosis , such as

fever , headache , arthralgias or bone

lymphocyte assays ; reverse western

in an endemic region — includes

an eschar at the site of tick bite and

endocarditis , endovascular infec-

pain , lymphadenopathy and abdom-

blots ; in-house criteria for interpreta-

other skin conditions , such as tinea

a maculopapular , vesicular or pete-

tions or chronic neuropathies . 22

inal pain . B . quintana or trench

tion of immunoblots ; measurements of antibodies in joint fluid ( synovial fluid ); and IgM or IgG tests without a

infection ( ringworm , see figure 7 ), erythema multiforme ( see figure 8 ) and discoid eczema ( see figures 9A

chial rash ; however , in rare cases , a rash may not develop . 21 The incubation period for rickettsial infec-

Bartonellosis — caused by the gram-negative intracellular bacteria Bartonella sp . — can have simi-

fever is transmitted by the bite of the human body louse and primarily causes fever and bone pain . Bar-

screening EIA test . 20

and B ).

tions is 1-2 weeks , and infections

lar features to disseminated Lyme

tonellosis can also affect many