Why is Lyme disease not officially recognized by authorities in Australia?

Lyme disease syndrome has been reported in Australia since 1982 (Hunter Valley, NSW) and yet the authorities still do not recognize that it is endemic in Australia and it is not recognized as a notifiable disease in Australia. However The Australian Government is monitoring Lyme disease, in consultation with the states and territories, through the Communicable Diseases Network Australia. The public health department set up a Clinical AdvisoryCommittee on Lyme Disease (CACLD). They reported back in July 2014 that there were 2 schools of thought about whether Lyme existed in Australia:

1.       Those who believe that an indigenous form of Lyme disease exists in AustraliaT
2.     Those who are not prepared to exclude the existence of an indigenous form but who require proof of its existence. Proof would be in the form of  identifying and characterising the causative microorganism; and also  identifying the indigenous blood feeding vector

Following on from that the University of Sydney, Departmentof Medical Entomology conducted a survey to ascertain whether Lyme disease occurs in the southern hemisphere in general, and in Australia in particular.

Is there atick vector of Lyme disease in Australia?

Problems with Diagnosis.

Some of the skepticism around Lyme disease in Australia is because of the difficulty in diagnosing the disease and the general controversy around which tests are best to use.

Serological testing using current methods to detect antibodies against Lyme disease are acknowledged to have limitations due to the general lack of sensitivity and specificity.  Serological tests can give false negative results especially in the early stages of the disease and because of the degree of cross reactivity of the Borrelia sp. The percent of false positive results is very high. A two tiered approach is adopted by most countries which uses the ELISA test as a screening test and positives are then followed up with the more specific Western Bloc technique.

In Australia this testing regimen is further complicated because there has been no isolation of the causative organism of Lyme disease in Australia so the antigen used in the testing to date if from the USA and Europe and may not be suitable for Australian conditions. But until the causative organism has be isolated in Australia the test using overseas antigens may not be sensitive or specific enough.

The sensitivity of serological testing for Lyme disease depends on the strain of Borrelia used in the testing and this affects results in Australia, where no local spirochete has been isolated for use as a reference antigen. This means that testing is done using.  North American and European strains of Borrelia which may not be suitable for Australian testing.

 Members of the Advisory Committee were pushing for Australian testing capability to focus more on the detection of the causative agent itself, either by cultural techniques or by detecting the causative organisms' DNA using nucleic acid amplification techniques.

In Australia, not all labs have the capability nor accreditation required to test for Lyme disease and results of the same blood being sent to various labs come up with different results many. Many pro Lyme doctors send the samples overseas for testing.

Over the past 6 years there has been an increase in serological testing for Lyme disease in Australia. However most patients request the test themselves on the basis of tick exposure and symptoms which suggest Lyme disease such as myalgia, arthralgia without objective evidence of joint disease, neurological symptoms such as frequent headaches, inability to concentrate and impairment of memory, and syndromes resembling chronic fatigue syndrome. Some have positive screening serology but many have not been confirmed with a more specific western bloc test.

None of the testing on local patients done at Westmead hospital who were positive for Lyme disease screening tests done in Australia to date have produced results that conform with internationally accepted criteria for a positive Western Bloc test. The positive screening tests are likely to be due to cross reactivity, or maybe due to the fact that the "Australian antigen" has not yet been isolated and used in testing. 

However these false positive screening tests casts doubt on whether Lyme disease has been confirmed in Australia. The diagnosis of Lyme disease outside of known endemic areas cannot be based solely on serological tests especially when they fail to conform with internationally accepted criteria, because of the high incidence of false positive results.

Problems with identifying typical skin rash, and clinical diagnosis

A few cases of Erythema Migrans rash have been reported from South-Eastern Australia. However, diagnosis can be confusing because of the erythematous hypersensitivity reaction to the bite of I. holocyclus, the most common tick biting humans.  There has been no isolation of Borrelia from skin lesions of local Australian patients. 

A clinical diagnosis in a non-endemic disease area especially in the later stages, is difficult to support without isolation of the causative agent from the patient, from other patients with similar illness or from a known vector in the region. So until diagnosis is confirmed with "concrete" evidence the symptoms of Lyme disease will not be recognized in Australia.

The proponents of long term infection and the existence of dormancy rely on the acceptance of specific bacterial pleomorphism for Borrelia species

Problems with treatment

The advisory committee say that the development of an Australian treatment protocol rests on an accepted diagnostic pathway plus a clinical evaluation of the patients with long term manifestations after an initial diagnosis of Lyme disease in Australia. It is not currently possible with the available diagnostic assays, including nucleic acid amplification assays, to determine if long term infection and disease exists in Australia. 

Vector and reservoir host Investigations – Australia

No ticks of the I. persulcatus complex which are the principal vectors of Lyme disease to humans in the northern hemisphere and in Eurasia, occur in Australia.  However, a possible vector which could transmit Lyme disease from its natural reservoir to humans has been identified in Eastern Australia. A species of tick known as I. holocyclus, which has a wide host range, is the most common tick biting humans.  But I. holocyclus, is unable to transmit the North American strain of B.burgdorferi. However the question remains as to whether there is a so far undiscovered Australian spirochete responsible for Lyme disease in Australia.

  

A natural reservoir for Lyme disease has not been identified in Australia. None of the mammal species identified as reservoir hosts in the northern hemisphere are present in Australia. There are reports of spirochetes being isolated from Australian native animals, and a local mammal could be a reservoir host for an Australian spirochete that occasionally infects humans through a tick vector and produces a clinical syndrome similar to Lyme disease; however, no spirochetes were detected in the 12,000 ticks or animals processed in a recent survey.

In this survey of over 12,000 ticks and a handful of native animals, researchers failed to identify Borrelia. Testing was done by 3 methods:

1. 1     Dark field microscopy of the tick's gut content
2. 2.       Culture to  isolate grow the causative organism
3. 3.       Detection of Borrelia genes by PCR technology (the primers were sourced from overseas and may not be specific for Australia.

Summary

The existence of Lyme disease in Australia will remain controversial until an organism is isolated from a local patient and fully characterized, or until a tick-borne organism can be shown to be responsible for the human infection. If it exists it shares few of the epidemiological or clinical characteristics of US or European patterns of Lyme disease. And this is why is Lyme disease is not officially recognized by authorities in Australia.

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