Indirect versus direct detection methods of Trichinella spp. infection in wild boar (Sus scrofa)

Abstract

BackgroundTrichinella spp. infections in wild boar (Sus scrofa), one of the main sources of human trichinellosis, continue to represent a public health problem. The detection of Trichinella spp. larvae in muscles of wild boar by digestion can prevent the occurrence of clinical trichinellosis in humans. However, the analytical sensitivity of digestion in the detection process is dependent on the quantity of tested muscle. Consequently, large quantities of muscle have to be digested to warrant surveillance programs, or more sensitive tests need to be employed. The use of indirect detection methods, such as the ELISA to detect Trichinella spp. infections in wild boar has limitations due to its low specificity. The aim of the study was to implement serological detection of anti-Trichinella spp. antibodies in meat juices from hunted wild boar for the surveillance of Trichinella spp. infections.MethodsTwo tests were used, ELISA for the initial screening test, and a specific and sensitive Western blot (Wb) as a confirmatory test. The circulation of anti-Trichinella IgG was determined in hunted wild boar muscle juice samples in 9 provinces of 5 Italian regions.ResultsFrom 1,462 muscle fluid samples, 315 (21.5%, 95% C.I. 19.51-23.73) were tested positive by ELISA. The 315 ELISA-positive muscle fluid samples were further tested by Wb and 32 (10.1%, 95% C.I. 7.29-13.99) of these were positive with a final seroprevalence of 2.2% (95% C.I 1.55-3.07; 32/1,462). Trichinella britovi larvae were detected by artificial digestion in muscle tissues of one (0.07%, 95%C.I. 0.01-0.39) out of the 1,462 hunted wild boars. No Trichinella spp. larvae were detected in Wb-negative wild boar. From 2006 to 2012, a prevalence of 0.017% was detected by muscle digestion in wild boar hunted in the whole Italian territory.ConclusionsThe combined use of both serological methods had a sensitivity 31.4 times higher than that of the digestion (32/1,462 versus 1/1,462), suggesting their potential use for the surveillance of the Trichinella spp. infection in wild boar populations.

The red fox ( Vulpes vulpes ) plays a minor role in the epidemiology of the domestic cycle of Trichinella in Romania

“…These data and the results of the present investigation suggest that two independent cycles exists in Romania: 1. a T. britovi cycle in the wild in which carnivores, particularly foxes, act as reservoirs, and 2. a T. spiralis cycle in which wild boar and pigs act as the most important reservoirs. T. britovi seldom reaches the domestic habitat to infect pigs because this parasite species survives for a short period of time in swine (Gómez-Morales et al, 2014).…”

T‐cell clones in human trichinellosis: Evidence for a mixed Th1/Th2 response

“…Serum samples were first tested for the presence of anti‐ Trichinella IgG using excretory/secretory antigens (ESA) from T. spiralis larvae by an in‐house ELISA according to a published protocol . ELISA‐positive serum samples were further tested by Western blotting (Wb) to confirm the presence of anti‐ Trichinella IgG according to a previously published protocol, which uses a high‐sensitive revelation system based on chemiluminescence …”

“…To detect anti‐ Trichinella IgE, nitrocellulose strips were incubated with a 1:5 diluted serum samples prepared according to Gomez Morales et al . After washing, the membranes were incubated with a 1:10 000 dilution rat monoclonal anti‐human IgE (Ingenasa, Madrid, Spain) for 3 hours.…”

First Report of the Occurrence of Trichinella-Specific Antibodies in Domestic Pigs in Central and Eastern Uganda

“…As shown in other studies, unspecific cross-reactions may not be fully excluded; therefore, a Western Blot was used for confirmatory testing. Reportedly, the combined use of both serological methods shows a sensitivity that is 31.4 times higher than that of the digestion assay [43], especially in naturally infected wild pigs with a lower larval burden. Western Blot based on somatic antigen allows discriminating ELISA positive samples further because it includes all relevant protein fractions of the E/S antigen (43–45 and 66–67 kDa) and fractions 47, 61 and 102 kDa which are Trichinella -specific [35,36].…”