No Serological Evidence of Trachoma or Yaws Among Residents of Registered Camps and Makeshift Settlements in Cox's Bazar, Bangladesh.

Successful achievement of global targets for elimination of trachoma as a public health problem and eradication of yaws will require control efforts to reach marginalized populations, including refugees. Testing for serologic evidence of transmission of trachoma and yaws in residents of registered camps and a Makeshift Settlement in Cox's Bazar District, Bangladesh, was added to a serosurvey for vaccine-preventable diseases (VPDs) conducted April-May 2018. The survey was primarily designed to estimate remaining immunity gaps for VPDs, including diphtheria, measles, rubella, and polio. Blood specimens from 1- to 14-year-olds from selected households were collected and tested for antibody responses against antigens from Treponema pallidum and Chlamydia trachomatis using a multiplex bead assay to evaluate for serologic evidence of the neglected tropical diseases (NTDs) yaws and trachoma, respectively. The prevalence of antibodies against two C. trachomatis antigens in children ranged from 1.4% to 1.5% for Pgp3 and 2.8% to 7.0% for CT694. The prevalence of antibody responses against both of two treponemal antigens (recombinant protein17 and treponemal membrane protein A) tested was 0% to 0.15% in two camps. The data are suggestive of very low or no transmission of trachoma and yaws, currently or previously, in children resident in these communities. This study illustrates how integrated serologic testing can provide needed data to help NTD programs prioritize limited resources.

Community-based mass treatment with azithromycin for the elimination of yaws in Ghana-Results of a pilot study.

INTRODUCTION: The WHO yaws eradication strategy consists of one round of total community treatment (TCT) of single-dose azithromycin with coverage of > 90%.The efficacy of the strategy to reduce the levels on infection has been demonstrated previously in isolated island communities in the Pacific region. We aimed to determine the efficacy of a single round of TCT with azithromycin to achieve a decrease in yaws prevalence in communities that are endemic for yaws and surrounded by other yaws-endemic areas. METHODS: Surveys for yaws seroprevalence and prevalence of skin lesions were conducted among schoolchildren aged 5-15 years before and one year after the TCT intervention in the Abamkrom sub-district of Ghana. We used a cluster design with the schools as the primary sampling unit. Among 20 eligible primary schools in the sub district, 10 were assigned to the baseline survey and 10 to the post-TCT survey. The field teams conducted a physical examination for skin lesions and a dual point-of-care immunoassay for non-treponemal and treponemal antibodies of all children present at the time of the visit. We also undertook surveys with non-probabilistic sampling to collect lesion swabs for etiology and macrolide resistance assessment. RESULTS: At baseline 14,548 (89%) of 16,287 population in the sub-district received treatment during TCT. Following one round of TCT, the prevalence of dual seropositivity among all children decreased from 10.9% (103/943) pre-TCT to 2.2% (27/1211) post-TCT (OR 0.19; 95%CI 0.09-0.37). The prevalence of serologically confirmed skin lesions consistent with active yaws was reduced from 5.7% (54/943) pre-TCT to 0.6% (7/1211) post-TCT (OR 0.10; 95% CI 0.25-0.35). No evidence of resistance to macrolides against Treponema pallidum subsp. pertenue was seen. DISCUSSION: A single round of high coverage TCT with azithromycin in a yaws affected sub-district adjoining other endemic areas is effective in reducing the prevalence of seropositive children and the prevalence of early skin lesions consistent with yaws one year following the intervention. These results suggest that national yaws eradication programmes may plan the gradual expansion of mass treatment interventions without high short-term risk of reintroduction of infection from contiguous untreated endemic areas.

Treponema pallidum subsp. pertenue displays pathogenic properties different from those of T. pallidum subsp. pallidum.

The present study described the susceptibility of C4D guinea pigs to cutaneous infection with Treponema pallidum subsp. pertenue Haiti B strain. The general manifestations of the disease in adults and neonates differ, to a certain degree, from those induced by T. pallidum subsp. pallidum Nichols strain. Noticeable differences between the infections were reflected in the character of the skin lesions, their onset and persistence, and the kinetics of the humoral response. The incidence and dissemination of cutaneous yaws lesions in very young guinea pigs were remarkably different from the low frequency observed in a similar age group of syphilis infection, 100 versus 17%, respectively. Moreover, as opposed to T. pallidum subsp. pallidum, T. pallidum subsp. pertenue does not cross the placenta. Offspring born to yaws-infected mothers did not produce immunoglobulin M antibodies and their organs, examined by PCR and rabbit infectivity test (RIT), were all negative. Examination of a large number of tissues and organs in adult, neonate, and maternal yaws by PCR and RIT clearly demonstrated that, unlike syphilis, there was a low incidence and short persistence of the yaws pathogen in internal organs. These findings stress the dermotropic rather than the organotropic character of yaws and provide further evidence of distinctive biological and pathological differences between yaws and venereal syphilis.

Evaluation of immunoglobulin G enzyme immunoassay for serodiagnosis of yaws.

A commercially available enzyme immunoassay (EIA), the Captia Syphilis-G immunoglobulin G (IgG) EIA, for the detection of IgG antibodies to Treponema pallidum was evaluated for use as a screening test for yaws (Treponema pallidum subsp. pertenue). The IgG EIA was compared with the fluorescent treponemal antibody absorption (FTA-ABS) test. All sera were also examined by the T. pallidum hemagglutination test and the Venereal Disease Research Laboratory test. Serum samples from 271 subjects (23 control serum samples from an area nonendemic for yaws, 58 control serum samples from an area endemic for yaws, and 190 serum samples from yaws patients and contacts) were investigated. The overall agreement between the IgG EIA and the FTA-ABS test was 90%, the sensitivity was 99%, and the specificity was 70.2%. The specificity fell as the endemicity of the disease increased: from 94.4% in the nonendemic area controls to 86.4% in the endemic area controls and to 52.3% in the yaws contacts. There was no difference in specificity between children and adults within each of the three groups. Fifteen children with clinical yaws were monitored for 9 months after treatment. The level of treponemal antibody fell consistently in 9 of the 15 children as measured by the antibody index (ratio of absorbance of the test serum to the mean absorbance of the low-titer-positive controls). Reinfection was seen in three children, with the antibody index rising with the Venereal Disease Research Laboratory test titer. The Captia Syphilis-G test is a sensitive assay for the detection of treponemal antibodies in yaws patients. However, the apparent low specificity of the test in the yaws endemic area limits its use as a screening test for yaws.

The localisation of treponemes and characterisation of the inflammatory infiltrate in skin biopsies from patients with primary or secondary syphilis, or early infectious yaws.

OBJECTIVE: To study the localisation of treponemes and to analyse the inflammatory infiltrate in biopsy specimens from patients with primary or secondary syphilis, or early infectious yaws. MATERIALS AND METHODS: Skin biopsies originating from human lesions of primary (29x) or secondary (15x) syphilis (Rotterdam), or early yaws (18x) (West Sumatra) were studied. Different histochemical and immunohistochemical detection methods were used in this study. RESULTS AND CONCLUSION: The histochemical silver staining method according to Steiner revealed the presence of T. pallidum in all cases of primary syphilis studied. In 10 out of 14 cases of secondary syphilis, treponemes were demonstrated. With an immunofluorescence staining technique (IF) using anti-T. pallidum antiserum raised in rabbits (a-Tp), T. pallidum was demonstrated in 28 out of 29 cases of primary syphilis, and in 14 out of 14 studied cases of secondary syphilis. The silver staining method and IF showed identical localisations of T. pallidum (mainly in the dermal-epidermal junction zone or throughout the dermis). Using a-Tp antiserum in the indirect immunofluorescence technique, T. pertenue could be demonstrated in the dermis more often than with Steiner silver staining. However, epidermotropism of T. pertenue in yaws specimens was remarkable, compared with more mesodermotropism of T. pallidum; numbers of T. pertenue in the dermis were limited in all specimens. The dermal inflammatory infiltrate in primary and secondary syphilis was composed mainly of lymphocytes and plasma cells. In most cases more T (CD3 positive) cells than B (CD22 positive) cells were present. Regarding T cell subpopulations, in primary syphilis, T helper/inducer (CD4 positive) cells predominated in 86% of cases. In secondary syphilitic lesions, numbers of T helper/inducer cells were less frequent than or equal to T-suppressor/cytotoxic (CD8 positive) cells in 60% of cases. Remarkably, in yaws specimens the inflammatory infiltrate consisted mainly of IgG, but also IgA and IgM producing plasma cells. T or B lymphocytes were scarce, which is in sharp contrast with findings in syphilitic lesions.

Immune response to Treponema pertenue and Treponema pallidum Nichols in patients with yaws.

Human sera from African patients with acute yaws were analysed by Western blot (WB) against antigens of Treponema pallidum Nichols and two Treponema pertenue isolates. The Western blot patterns were remarkably similar from one patient to another, and strains of both subspecies exhibited exactly the same banding pattern. Sera from yaws patients failed to detect at least one antigen in T. pertenue which was absent from T. pallidum.

The effect of C3 depletion on resistance of hamsters to infection with the yaws spirochete.

The role of complement in humoral-mediated resistance to frambesial infection (yaws) needs to be defined. The level of serum C3 was reduced shortly after infection of hamsters with Treponema pallidum subspecies pertenue. Five weeks after frambesial infection, the serum C3 level began to increase and by week 7 no difference was detected between infected and uninfected hamsters. When C3 was depleted in hamsters by injection of 20 units of cobra venom factor (CoVF), two alterations in host resistance to frambesial infection occurred. Depletion of C3 abrogated the ability of immune serum to confer complete protection on normal hamsters against infection with the yaws spirochete. In all hamsters receiving immune serum but not CoVF, lesions failed to develop and lymph nodes weighed significantly less (P less than or equal to 0.1) than those of controls. Furthermore, no treponemes were detected in the lymph nodes of passively immunized animals. Second, depletion of C3 increased the susceptibility of hamsters to frambesial infection. The onset and progression of frambesial lesions were enhanced as compared with frambesial-infected hamsters not treated with CoVF. Finally, CoVF treatment did not reduce the ability of frambesia-immune hamsters cured of disease with penicillin to resist reinfection. These results demonstrate that complement influences the pathogenesis of yaws.

Effect of immune serum and its immunoglobulin fractions on hamsters challenged with Treponema pallidum ssp. pertenue.

Passive transfer of frambesial immune serum is capable of conferring complete protection on hamsters against challenge with Treponema pallidum ssp. pertenue. Treponemicidal activity in the pooled immune serum is relatively high. Immune serum and its immunoglobulin fractions, especially IgG2, also killed T. pallidum ssp. pertenue in vitro. Treponemicidal activity was present only when immune serum was administered to hamsters within a short time (three days) of frambesial challenge. By contrast, administration of pooled immune serum to hamsters infected for more than one week failed to reduce the number and size of lesions and the weight and number of treponemes in the lymph nodes. These results suggest that hamsters can develop the humoral components necessary to protect them against frambesial challenge, but these components are unable to destroy treponemes at the primary foci of infection.

Immunodiagnostic test for detection of serum antibody to Treponema pallidum (syphilis): fibronectin as a capture vehicle for treponemal adhesins.

Knowledge that Treponema pallidum adhesin proteins bind to host fibronectin (Fn) via ligand-receptor interactions has resulted in development of an ELISA for measuring specific antitreponemal antibodies in sera of syphilitic patients and infected experimental animals. As little as 50 ng of T. pallidum total protein extract added to Fn-coated wells permitted half-maximal levels of ELISA reactivity. Detection of serum antibody from intratesticularly infected rabbits occurred at dilutions greater than 1/100,000. Antibody titers in serum from patients with primary and latent syphilis were positive at 1/1 000 dilutions while serum samples from patients with secondary syphilis were reactive at 1/10,000. Furthermore, the ELISA proved useful for evaluating serum samples from individuals with other treponemal infections. Antibodies raised against the non-pathogenic spirochete, T. phagedenis biotype Reiter, were non-reactive with Fn-T. pallidum complexes. Also, Reiter treponemal proteins did not bind to Fn-coated wells. This ELISA using Fn as a capture vehicle for treponemal adhesin proteins was superior to 3 other routinely used tests for syphilis diagnosis.

Research: the prerequisite for innovative strategies and technologies.

The search for new strategies and technologies for the control of yaws, a genuine but much neglected tropical disease problem, has been largely unsuccessful. This disease, with conspicuous early symptoms and a late crippling pathology, attracted the attention of the first generation of tropical doctors. As soon as specific therapy became available in the early part of the 20th century, mass treatment campaigns were started. The availability and efficacy of penicillin led some to anticipate yaws eradication; this expectation was not met but rather induced a false sense of security. After varying intervals resurgences occurred in several endemic regions. It is important to analyze this failure so that mistakes and underestimated or overlooked factors can be identified. On the whole, the main difficulty has been a lack of interest in a presumably disappearing disease and a consequent failure to take advantage of the benefits offered by recent advances in basic biomedical technology. Solid clinical, epidemiologic, and sociocultural data in connection with mass treatment and control are still needed. Research of high quality, with continuous assessment in the field, is a prerequisite for innovative strategies and technologies.

Effect of local and systemic macrophage activation in hamsters on infection with Treponema pertenue and Treponema pallidum Bosnia A.

The role of nonspecific macrophage activation in the destruction of treponemes needs to be defined. Studies have been hindered by an inability to confirm that macrophages have enhanced bactericidal activity at the site of treponemal infection. We show that subcutaneous and intravenous vaccination with BCG (Mycobacterium bovis) induces macrophage activation in hamsters, as determined by an enhanced ability to suppress the growth of Listeria monocytogenes in the livers, spleens, and inguinal lymph nodes. However, hamsters challenged in the inguinal region with Treponema pertenue during periods of enhanced microbial resistance (3 to 8 weeks after BCG vaccination) developed lesions faster and with more necrosis. Increased numbers of treponemes were recovered from the regional lymph nodes of BCG-vaccinated hamsters than from nonvaccinated controls, although the differences were not statistically significant. No pathological differences were detected in BCG-vaccinated and non-vaccinated hamsters challenged with Treponema pallidum Bosnia A. These studies demonstrate that BCG vaccination influences the pathogenesis of some treponemal diseases without inducing macrophage-mediated treponemicidal activity.

Acquired resistance of hamsters to challenge with homologous and heterologous virulent treponemes.

Hamsters infected with Treponema pallidum Nichols (venereal syphilis), T. pallidum Bosnia A (endemic syphilis), or T. pertenue (frambesia, or yaws) developed substantial resistance to homologous reinfection. Hamsters infected for 10 weeks developed no lesions, and their lymph nodes contained fewer treponemes after reinfection with the same strain. The degree of cross-resistance among the treponemes correlated well with pathological changes occurring in infected hamsters and with the persistence of treponemal antigen during primary infection. Only hamsters infected with T. pallidum Bosnia A developed substantial resistance to heterologous reinfection. These animals also had extensive chronic skin lesions and lymph nodes containing measurable numbers of treponemes. Frambesial hamsters had less extensive lesions and were resistant to T. pallidum Nichols and, to a lesser extent, to T. pallidum Bosnia A. Hamsters infected with T. pallidum Nichols developed no cutaneous lesions and were resistant only to reinfection with T. pertenue. Confirmation of these results was obtained in normal hamsters infused with syphilitic (Nichols or Bosnia A) or frambesial immune cells and challenged with homologous or heterologous treponemes.

Molecular characterization of receptor binding proteins and immunogens of virulent Treponema pallidum.

Receptor binding proteins of Treponema pallidum were identified by incubation of [35S]methionine-labeled, soluble T. pallidum preparations with formaldehyde-fixed HEp-2 cells. Three major treponemal proteins (bands 1--3) that avidly bound to the eucaryotic cell surface were detected by sodium dodecylsulfate-polyacrylamide gel electrophoresis and fluorography. Brief trypsin treatment of HEp-2 cells before formaldehyde fixation reduced the extent of the interaction of these treponemal macromolecules, which implicated receptor-mediated attachment mechanisms. The presence of unlabeled T. pallidum preparations directly competed with radiolabeled T. pallidum samples for the available HEp-2 cells, which suggested a limiting number of membrane binding sites. Samples of unlabeled avirulent Reiter treponeme did not compete. T. Pallidum immunogens were examined by radioimmunoprecipitation with human and rabbit syphilitic sera. Of interest were the similarities and extent of the humoral response represented by the detection of antigen-antibody complexes against numberous treponemal proteins, including bands 1--3. T. pallidum portein band 1 appeared to be the major antigenic stimulus. Formation of antigen-antibody complexes between 35S-labeled T. pallidum proteins and human syphilitic sera was prevented by unlabeled T. pallidum but not by T. phagedenis preparations, which demonstrated specificity of the reaction. Gel profiles of radioimmunoprecipitation assays using radiolabeled T. pallidum antigens and human syphilitic and yaws sera delineated both the similarities and differences in the humoral response to these two spirochetes. The latter suggested both overlapping and distinguishing antigenic properties between T. pallidum and T. pertenue. Detection in yaws sera of specific antibody against T. pallidum protein bands 1--3 further incriminates the role of these three treponemal proteins as virulence determinants.

Analysis of the anticomplementary activity in sera of three African patients with parasitic and bacteriological infections.

The sera of three different patients from Togo, Africa were investigated with respect to their complement profile. The three patients were suffering from parasitic (Onchocerca volvulus) and bacteriological (Treponema pertenue) diseases. The total hemolytic activity (50% hemolytic complement) was markedly depressed. The analysis of the individual complement components revealed the the titers of C1, C2, C3, and C4 were lowered up to 90%, indicating an activation of the classical pathway of complement. Addition of the patients' sera to normal human serum induced a temperature-dependent consumption of C4 and C2, whereas C3 was not affected. This activity in the patients' sera eluted from a Sephadex-G-200 column with the 19 S peak and could be identified as the activated form of the first component of the complement system. The reason for the presence of activated C1, C1 in the patients' sera resides in the absence of functionally active C1 inactivator.

Use of CB hamsters in the study of Treponema pertenue.

The CB/Ss LAK strain of inbred hamster was used as a model for studies of infection with Treponema pertenue and of acquired resistance to it. When infected, this strain developed cutaneous lesions which lasted for six to seven months, even in the presence of peak titres of antitreponemal antibody. The rate of appearance and resolution of these lesions varied with the size of the inoculum. The infected hamsters' inguinal lymph nodes increased significantly in weight and teemed with treponemes for several weeks. Animals infected for eight or 10 weeks obtained quick resolution of their lesions by treatment with penicillin and were thereafter resistant to reinfection.