Table 1 Current parasitological techniques, related challenges and research needs for a potential application of MALDI-TOF MS as diagnostic tool for major helminths of human and veterinary importance

Helminth species

Soil-transmitted helminths: Ascaris lumbricoides; hookworm; Strongyloides stercoralis; Trichuris trichiura

Tissue nematodes: Dirofilaria spp.; Trichinella spp.; Toxocara spp.; Wuchereria bancrofti and other agents causing lymphatic filariasis, Onchocerca volvulus, Loa loa; animal hookworms causing cutaneous larva migrans

Taenia spp.; Diphyllobothrium latum

Echinococcus spp.

Schistosoma spp.; Fasciola hepatica; small liver flukes

Type of diagnostic sample

(i) Stool;

(ii) Excreted worms

(i) Tissue samples;

(ii) Serum;

(iii) Extracted worms (e.g. Loa loa)

(i) Stool;

(ii) Serum (for T. solium);

(iii) Tissue samples in cysticercosis;

(iv) Excreted proglottids

(i) Stool (in animals);

(ii) Tissue biopsies, surgical samples;

(iii) Serology

(i) Stool;

(ii) Urine;

(iii) Serum;

(iv) Tissue biopsies

Parasitological standard diagnostic techniques

(i) Stool microscopy (e.g. Kato-Katz technique);

(ii) PCR in reference laboratories

(i) Direct identification on biopsy samples;

(ii) Serology;

(iii) PCR in reference laboratories;

(iv) Detection of microfilariae in blood;

(v) Detection of antigen in blood (Wuchereria)

(i) Direct identification of faecally excreted proglottids;

(ii) Stool microscopy;

(iii) Serology

(i) Microscopy;

(ii) PCR of cysts and tissue samples;

(iii) Serology

(i) Stool/urine microscopy (dependent on infecting species);

(ii) Rapid diagnostic test for circulating cathodic antigen (CCA) in urine;

(iii) PCR on serum, stool or urine;

(iv) Serology

Difficulties related to currently employed diagnostics

(i) Low sensitivity in light infection intensities;

(ii) Specific concentration techniques needed for S. stercoralis;

(iii) Misidentification of hookworm and S. stercoralis larvae possible;

(iv) No species differentiation between different hookworm species possible upon microscopy

(i) Serology frequently false-negative;

(ii) False-negative PCR results in case of ‘new’ species;

(iii) Lack of expertise outside specialized laboratories

(i) Eggs of related Taenia spp. are indistinguishable by microscopy;

(ii) Lack of expertise in proglottid differentiation in many laboratories

(i) Serology frequently false-negative in intact cysts;

(ii) Microscopy (similar morphology) and serology (cross-reactivity) cannot reliably distinguish between Echinococcus spp. (therapeutic implications)

(i) Low sensitivity in light infection intensities;

(ii) Microscopy and PCR fail to detect hybrid species

Research needs for MALDI-TOF application

(i) Establishment of a database for identification of eggs/larvae and adult worms;

(ii) Differentiation of microscopically indistinguishable hookworm species;

(iii) Protocol development for application on stool samples and bronchial specimens

(i) Establishment of a database for identification of tissue-invasive helminths;

(ii) Species differentiation within one genus (e.g. Dirofilaria);

(iii) Application on biopsy specimens;

(iv) Detection of microfilariae in blood;

(v) Detection of antigen in blood (e.g. Wuchereria spp.)

(i) Establishment of a database for identification of Taenia proglottids and eggs;

(ii) Differentiation between T. solium eggs/proglottids and other Taenia spp.;

(iii) Protocol development for application on stool specimens

(i) Establishment of a database for species-specific identification of eggs and tissue cysts;

(ii) Protocol for application on different sample types

(i) Establishment of a database for species-specific identification;

(ii) Protocol for application on different sample types;

(iii) Detection of Schistosoma antigen(s) in serum;

(iv) Detection of products derived from helminth-specific metabolism in serum samples