Diagnosis of Parasitic Infections: What’s Going On?

Abstract

Methods for the diagnosis of parasitic infections have stagnated in the past three decades. Labor-intensive methods such as microscopy still remain the mainstay of several diagnostic laboratories. There is a need for more rapid tests that do not sacrifice sensitivity and that can be used in both clinical settings as well as in poor resource field settings. The fields of diagnostic medical parasitology, treatment, and vaccines are undergoing dramatic change. In recent years, there has been tremendous effort to focus research on the development of newer diagnostic methods focusing on serological, molecular, and proteomic approaches. This article examines the various diagnostic tools that are being used in clinical laboratories, optimized in reference laboratories, and employed in mass screening programs.

Barcoding in trypanosomes

“…Antibody-detection tests, such as the card agglutination tests and the direct agglutination test, are widely used for the detection of trypanosomes in human hosts (Ricciardi and Ndao, 2015;Lutumba et al 2016). These tests have excellent field application as they do not require a constant supply of electricity and are cheaper and more rapid than equivalent molecular techniques, although they can vary significantly in their sensitivity and specificity (Ricciardi and Ndao, 2015).…”

“…These tests have excellent field application as they do not require a constant supply of electricity and are cheaper and more rapid than equivalent molecular techniques, although they can vary significantly in their sensitivity and specificity (Ricciardi and Ndao, 2015). Serological tests require relatively large samples and have the potential to yield falsenegative results where parasitaemia is low or where antibody production is reduced, such as in immunocompromised patients (Papadopoulos et al 2004;World Health Organisation, 2013).…”

“…Isothermal tests involve a single reaction in a single tube incubated at a constant temperature; therefore, these techniques do not require the expensive thermocycling equipment that is necessary for PCR Wastling and Welburn, 2011). The simplicity, sensitivity and low cost of isothermal techniques make them strong candidates for the application of molecular methods in field diagnostics in resource-poor areas (Laohasinnarong, 2011;Ricciardi and Ndao, 2015). However, a number of additional costs must be considered when evaluating the suitability of these methods for field diagnostics, including: the need for six primers, heating and maintaining samples at 65°C, and expensive dyes for visualization of results (Enyaru et al 2010;Wastling and Welburn, 2011).…”

“…Old faithful: microscopy Despite the development of a variety of molecular methods for the detection and identification of infectious agents, the usual method for diagnosing trypanosome infections in vertebrate hosts remains the most basic: microscopic examination of sample preparations (Mugasa et al 2012;Ricciardi and Ndao, 2015). However, this method is time consuming, dependent on operator expertise, unreliable for mixed infections, fails to detect immature infections and, in the case of African trypanosomes, is only useful for distinguishing between parasites to the level of subgenus (Ouma et al 2000;Gibson, 2009;Enyaru et al 2010;Auty et al 2012b;Mugasa et al 2014).…”

Diversity, impacts and diagnosis of pathogenic parasites in sea turtles from Queensland, Australia

“…Multiplex realtime PCR can be used to detect multiple gastrointestinal coccidians in faecal samples (Ricciardi and Ndao, 2015;Verweij et al, 2004). For species associated with multisystemic, disseminated infections such as Toxoplasma gondii, both serologic and molecular tests on blood samples can be utilised dependent on the immune status of the patient (Ricciardi and Ndao, 2015;Robert-Gangneux and Dardé, 2012).…”