In Practice

Spotted fever rickettsiosis in South Africa: Evaluation of laboratory diagnostic capacity and inter-laboratory comparison of serological testing

A N Trataris-Rebisz, J Rossouw, W Markotter, J A Frean, J Weyer

Abstract


Background. Spotted fever rickettsiosis, also known as tick bite fever (TBF), is a common infectious disease in South Africa (SA). Although the diagnosis of TBF is often based on clinical grounds only, laboratory testing is important to confirm the diagnosis and can contribute to case management in the light of a myriad of differential diagnoses, and in complicated cases.

Objectives. To report on the availability and scope of laboratory tests for investigating suspected cases of TBF in SA, and the outcome of an inter-laboratory comparison (ILC) conducted for serological tests.

Methods. A self-administered questionnaire was circulated to major pathology laboratories in SA to determine what TBF tests they offered for TBF investigation. In addition, a clinical panel was provided to willing laboratories in order to perform an ILC of the serological tests.

Results. Serological tests for TBF were available from five laboratories serving both the private and state medical sectors in SA. There was no standardised testing platform or result interpretation across the different laboratories. Polymerase chain reaction (PCR) tests were less frequently available, and not available to state-operated facilities. The outcome of the ILC indicated varied performance and interpretation of serological results for TBF.

Conclusions. Laboratory investigation for TBF is routinely and widely available in SA. Both serological and PCR-based methods were varied, and the lack of standardisation and interpretation of tests needs to be addressed to improve the overall quality of TBF diagnosis in SA. The utility of ILC to identify problem areas in serological testing for TBF is highlighted, and laboratories in SA are encouraged to use it to improve the quality of testing.

 

 


Authors' affiliations

A N Trataris-Rebisz, Centre for Emerging Zoonotic and Parasitic Diseases, National Institute for Communicable Diseases, National Health Laboratory Service, Johannesburg, South Africa; Department of Biochemistry, Genetics and Microbiology, Faculty of Agricultural Sciences, University of Pretoria, South Africa

J Rossouw, Centre for Emerging Zoonotic and Parasitic Diseases, National Institute for Communicable Diseases, National Health Laboratory Service, Johannesburg, South Africa

W Markotter, Centre for Viral Zoonoses, Department of Medical Virology, School of Medicine, Faculty of Health Sciences, University of Pretoria, South Africa

J A Frean, Centre for Emerging Zoonotic and Parasitic Diseases, National Institute for Communicable Diseases, National Health Laboratory Service, Johannesburg, South Africa; Wits Research Institute for Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa

J Weyer, Centre for Emerging Zoonotic and Parasitic Diseases, National Institute for Communicable Diseases, National Health Laboratory Service, Johannesburg, South Africa; Centre for Viral Zoonoses, Department of Medical Virology, School of Medicine, Faculty of Health Sciences, University of Pretoria, South Africa

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Keywords

Tick bite fever; Rickettsia; Rickettsiosis; South Africa; Inter-laboratory testing

Cite this article

South African Medical Journal 2019;109(4):223-226. DOI:10.7196/SAMJ.2019.v109i4.13788

Article History

Date submitted: 2019-03-29
Date published: 2019-03-29

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