Validation of Serological Tests for the Detection of Antibodies Against Treponema pallidum in Nonhuman Primates

Abstract

There is evidence to suggest that the yaws bacterium (Treponema pallidum ssp. pertenue) may exist in non-human primate populations residing in regions where yaws is endemic in humans. Especially in light of the fact that the World Health Organizaiton (WHO) recently launched its second yaws eradication campaign, there is a considerable need for reliable tools to identify treponemal infection in our closest relatives, African monkeys and great apes. It was hypothesized that commercially available serological tests detect simian anti-T. pallidum antibody in serum samples of baboons, with comparable sensitivity and specificity to their results on human sera. Test performances of five different treponemal tests (TTs) and two non-treponemal tests (NTTs) were evaluated using serum samples of 57 naturally T. pallidum-infected olive baboons (Papio anubis) from Lake Manyara National Park in Tanzania. The T. pallidum particle agglutination assay (TP-PA) was used as a gold standard for comparison. In addition, the overall infection status of the animals was used to further validate test performances. For most accurate results, only samples that originated from baboons of known infection status, as verified in a previous study by clinical inspection, PCR and immunohistochemistry, were included. All tests, TTs and NTTs, used in this study were able to reliably detect antibodies against T. pallidum in serum samples of infected baboons. The sensitivity of TTs ranged from 97.7-100%, while specificity was between 88.0-100.0%. The two NTTs detected anti-lipoidal antibodies in serum samples of infected baboons with a sensitivity of 83.3% whereas specificity was 100%. For screening purposes, the TT Espline TP provided the highest sensitivity and specificity and at the same time provided the most suitable format for use in the field. The enzyme immune assay Mastblot TP (IgG), however, could be considered as a confirmatory test.

High syphilis seropositivity in European brown hares ( Lepus europaeus ), Lower Saxony, Germany

“…Population size was based on wildlife survey data of Lower Saxony (Strauss, Ronnenberg, Klages, & Graeber, 2016). Test sensitivity (0.97) and specificity (0.92) were set according to the test performance reported in Knauf, Dahlmann, Batamuzi, Frischmann, and Liu (2015). Recent studies report a prevalence in EBHs from 33.0% to >74%, (Nováková et al, 2019; Verin, Pestelli, & Poli, 2012).…”

WidespreadTreponema pallidumInfection in Nonhuman Primates, Tanzania

“…The assay has been validated for use in baboons ( 12 ), where it performed with 97.7% (95% CI 87.7%–99.9%) sensitivity and 96.0% (95% CI 79.7%–99.9%) specificity. We tested serum samples on the day of sampling and operated and interpreted test cassettes according to the manufacturer’s guidance.…”

High syphilis seropositivity in European brown hares, Lower Saxony, Germany

“…Population size was used as shown in Table S1. Test sensitivity (0.97) and specificity (0.92) were set according to the test performance reported in Knauf et al 2012 [7]. Recent studies report a prevalence in EBHs from 33.0 to >74%, [8, 9].…”