Identifying wildlife reservoirs of neglected taeniid tapeworms : non-invasive diagnosis of endemic Taenia serialis infection in a wild primate population

Despite the global distribution and public health consequences of Taenia tapeworms, the life cycles of taeniids infecting wildlife hosts remain largely undescribed. The larval stage of Taenia serialis commonly parasitizes rodents and lagomorphs, but has been reported in a wide range of hosts that includes geladas (Theropithecus gelada), primates endemic to Ethiopia. Geladas exhibit protuberant larval cysts indicative of advanced T. serialis infection that are associated with high mortality. However, non-protuberant larvae can develop in deep tissue or the abdominal cavity, leading to underestimates of prevalence based solely on observable cysts. We adapted a non-invasive monoclonal antibody-based enzyme-linked immunosorbent assay (ELISA) to detect circulating Taenia spp. antigen in dried gelada urine. Analysis revealed that this assay was highly accurate in detecting Taenia antigen, with 98.4% specificity, 98.5% sensitivity, and an area under the curve of 0.99. We used this assay to investigate the prevalence of T. serialis infection in a wild gelada population, finding that infection is substantially more widespread than the occurrence of visible T. serialis cysts (16.4% tested positive at least once, while only 6% of the same population exhibited cysts). We examined whether age or sex predicted T. serialis infection as indicated by external cysts and antigen presence. Contrary to the female-bias observed in many Taenia-host systems, we found no significant sex bias in either cyst presence or antigen presence. Age, on the other hand, predicted cyst presence (older individuals were more likely to show cysts) but not antigen presence. We interpret this finding to indicate that T. serialis may infect individuals early in life but only result in visible disease later in life. This is the first application of an antigen ELISA to the study of larval Taenia infection in wildlife, opening the doors to the identification and description of infection dynamics in reservoir populations

Seroprevalence of Baylisascaris procyonis Infection among Humans, Santa Barbara County, California, USA, 2014–2016

Baylisascaris procyonis (raccoon roundworm) infection is common in raccoons and can cause devastating pathology in other animals, including humans. Limited information is available on the frequency of asymptomatic human infection. We tested 150 adults from California, USA, for B. procyonis antibodies; 11 were seropositive, suggesting that subclinical infection does occur

Development of a Luminex Bead Based Assay for Diagnosis of Toxocariasis Using Recombinant Antigens Tc-CTL-1 and Tc-TES-26.

The clinical spectrum of human disease caused by the roundworms Toxocara canis and Toxocara cati ranges from visceral and ocular larva migrans to covert toxocariasis. The parasite is not typically recovered in affected tissues, so detection of parasite-specific antibodies is usually necessary for establishing a diagnosis. The most reliable immunodiagnostic methods use the Toxocara excretory-secretory antigens (TES-Ag) in ELISA formats to detect Toxocara-specific antibodies. To eliminate the need for native parasite materials, we identified and purified immunodiagnostic antigens using 2D gel electrophoresis followed by electrospray ionization mass spectrometry. Three predominant immunoreactive proteins were found in the TES; all three had been previously described in the literature: Tc-CTL-1, Tc-TES-26, and Tc-MUC-3. We generated Escherichia coli expressed recombinant proteins for evaluation in Luminex based immunoassays. We were unable to produce a functional assay with the Tc-MUC-3 recombinant protein. Tc-CTL-1 and Tc-TES-26 were successfully coupled and tested using defined serum batteries. The use of both proteins together generated better results than if the proteins were used individually. The sensitivity and specificity of the assay for detecting visceral larval migrans using Tc-CTL-1 plus Tc-TES-26 was 99% and 94%, respectively; the sensitivity for detecting ocular larval migrans was 64%. The combined performance of the new assay was superior to the currently available EIA and could potentially be employed to replace current assays that rely on native TES-Ag

Specificity of the Toxocariasis Luminex assay.

<p>Specificity of the Toxocariasis Luminex assay.</p

Performance of Tc-CTL-1 and Tc-TES-26 Luminex based assays.

<p>Note</p><p>* = 95% Confidence Interval</p><p>Performance of Tc-CTL-1 and Tc-TES-26 Luminex based assays.</p

Identified proteins from mass spectrometry analysis.

<p>Note</p><p>+ = Molecular Weight</p><p>* = Sequence Coverage</p><p>Identified proteins from mass spectrometry analysis.</p

2-D gel electrophoresis, silver staining and western blotting of <i>Toxocara canis</i> Excretory Secretory Antigens (TES-Ag).

<p>The TES-Ag sample was separated and analyzed using 2D gel electrophoresis and western blotting. Three of the 2DE gels were transferred to nitrocellulose membranes and probed with a strong EIA positive <i>Toxocara</i> human sera pool (A), a negative human serum sample (B), and <i>Baylisascaris procyonis</i> positive serum (C).A reference gel was stained using silver stain (D). The circled spots in D represent proteins that were excised and subjected to mass spectrometry analysis.</p

Counts of log sample index values (IVs) (the optical density of each sample indexed to the positive and negative controls on each plate) + a constant.

<p>Blue bars indicate samples from individuals without cysts, while grey bars indicate samples from individuals with cysts. The dotted line indicates the optimal threshold cutoff for positive samples indicating antigen presence calculated with the ROC analysis.</p