Nonvenereal treponematoses: yaws, endemic syphilis, and pinta

Advancing the understanding of treponemal disease in the past and present

Syphilis was perceived to be a new disease in Europe in the late 15th century, igniting a debate about its origin that continues today in anthropological, historical, and medical circles. We move beyond this age-old debate using an interdisciplinary approach that tackles broader questions to advance the understanding of treponemal infection (syphilis, yaws, bejel, and pinta). How did the causative organism(s) and humans co-evolve? How did the related diseases caused by Treponema pallidum emerge in different parts of the world and affect people across both time and space? How are T. pallidum subspecies related to the treponeme causing pinta? The current state of scholarship in specific areas is reviewed with recommendations made to stimulate future work. Understanding treponemal biology, genetic relationships, epidemiology, and clinical manifestations is crucial for vaccine development today and for investigating the distribution of infection in both modern and past populations. Paleopathologists must improve diagnostic criteria and use a standard approach for recording skeletal lesions on archaeological human remains. Adequate contextualization of cultural and environmental conditions is necessary, including site dating and justification for any corrections made for marine or freshwater reservoir effects. Biogeochemical analyses may assess aquatic contributions to diet, physiological changes arising from treponemal disease and its treatments (e.g., mercury), or residential mobility of those affected. Shifting the focus from point of origin to investigating who is affected (e.g., by age/sex or socioeconomic status) and disease distribution (e.g., coastal/ inland, rural/urban) will advance our understanding of the treponemal disease and its impact on people through time.

A singular case of advanced caries sicca in a pre-Columbian skull from East Tennessee

OBJECTIVE

Documentation of an advanced case of tertiary stage treponemal disease.

MATERIALS

The well-preserved cranium and mandible of an adult male (Burial G) from the Early Woodland period (900 BCE-200 CE) Wilhoite site (40GN10) from east Tennessee.

METHODS

Macroscopic examination of the cranio-facial periostosis on Burial G for pathognomonic indicators of treponemal disease.

RESULTS

There are extensive contiguous nodular lesions on the frontal, parietals, temporals, and occipital bones. The frontal squama additionally exhibits radial scaring and circumvallate cavitating lesions. Radial scars are also present on both zygomatic bones and the endocranial surface of the calotte. There is rounding of the nasal margins in addition to periostosis on the palate.

CONCLUSIONS

Burial G unequivocally exhibits the pathognomonic reactive changes of caries sicca, radial scarring, and cavitating lesions.

SIGNIFICANCE

The Early Woodland date in combination with the advanced degree of pathognomonic reactive change is exceptional, and to date, without parallel in the pre-Columbian archaeological record of North America. Any case approaching the severity displayed here is invariably late prehistoric.

LIMITATIONS

The absence of postcrania does not permit assessment of frailty or synergism of secondary conditions.

SUGGESTIONS FOR FURTHER RESEARCH

More comprehensive documentation of pre-Columbian treponemal cases is merited.

Topical treatment with gallium maltolate reduces Treponema pallidum subsp. pertenue burden in primary experimental lesions in a rabbit model of yaws

Background

Gallium is a semi-metallic element known since the 1930s to have antimicrobial activity. This activity stems primarily from gallium's ability to mimic trivalent iron and disrupt specific Fe(III)-dependent pathways, particularly DNA synthesis (due to inhibition of ribonucleotide reductase). Because of its novel mechanism of action, gallium is currently being investigated as a new antibacterial agent, particularly in light of the increasing resistance of many pathogenic bacteria to existing antibiotics. Gallium maltolate (GaM) is being developed as an orally and topically administrable form of gallium. Yaws is a neglected tropical disease affecting mainly the skin and skeletal system of children in underprivileged settings. It is currently the object of a WHO-promoted eradication campaign using mass administration of the macrolide azithromycin, an antibiotic to which the yaws agent Treponema pallidum subsp. pertenue has slowly begun to develop genetic resistance.

Methods

Because yaws transmission is mainly due to direct skin contact with an infectious skin lesion, we evaluated the treponemicidal activity of GaM applied topically to skin lesions in a rabbit model of yaws. Treatment efficacy was evaluated by measuring lesion diameter, treponemal burden in lesion aspirates as determined by dark field microscopy and amplification of treponemal RNA, serology, and immunohistochemistry of biopsied tissue samples.

Results

Our results show that topical GaM was effective in reducing treponemal burden in yaws experimental lesions, particularly when applied at the first sign of lesion appearance but, as expected, did not prevent pathogen dissemination.

Conclusion

Early administration of GaM to yaws lesions could reduce the infectivity of the lesions and thus yaws transmission, potentially contributing to current and future yaws control campaigns.

Yaws is a neglected tropical disease affecting children in underprivileged countries, transmitted through direct skin contact with an active lesion. This infection, although rarely fatal, can lead to disfigurement and serious disability. The World Health Organization is currently conducting a yaws eradication effort that employs mass administration of azithromycin, an antibiotic against which the yaws pathogen has slowly begun to develop genetic resistance. Because this phenomenon has the potential to undermine the eradication effort, we investigated the antimicrobial activity of gallium maltolate, which has a novel mechanism of action, against the yaws pathogen. Our initial results show that topical application of gallium maltolate has significant treponemicidal activity, and suggest that this compound might find an application in the effort to eradicate yaws. Future studies will evaluate whether oral administration of gallium maltolate is as effective as the antibiotics currently approved for yaws treatment to clear systemic infection.

Advances in the Treatment of Yaws

Yaws is one of the three endemic treponematoses and is recognised by the World Health Organization as a neglected tropical disease. Yaws is currently reported in 15 countries in the Pacific, South-East Asia, West and Central Africa, predominantly affects children, and results in destructive lesions of the skin and soft tissues. For most of the twentieth century penicillin-based treatment was the standard of care and resistance to penicillin has still not been described. Recently, oral azithromycin has been shown to be an effective treatment for yaws, facilitating renewed yaws eradication efforts. Resistance to azithromycin is an emerging threat and close surveillance will be required as yaws eradication efforts are scaled up globally.

Endemic syphilis in Europe

Nonvenereal syphilis (endemic syphilis) has existed in Europe since the 16th century. Main characteristics of the disease are its presence for a longer time in a specific territory and its transmission regardless of age and sex, mainly extragenitally in unsanitary living conditions. Nonvenereal syphilis was described under different names in almost all regions of Europe. The primary genital chancre was absent, and lesions were most frequently found in the mouth and affected mostly children. The disease spread in rural areas with poor economic and hygienic conditions. The disease was eradicated in Europe in the 20th century, but it is still present in some rural regions of the Arabian Peninsula, Southwest Asia, and North Africa.

Endemic treponemal diseases

The endemic treponemal diseases, consisting of yaws, bejel (endemic syphilis) and pinta, are non-venereal infections closely related to syphilis, and are recognized by WHO as neglected tropical diseases (NTDs). Despite previous worldwide eradication efforts the prevalence of yaws has rebounded in recent years and the disease is now a major public health problem in 14 countries. Adequate data on the epidemiology of bejel and pinta is lacking. Each disease is restricted to a specific ecological niche but all predominantly affect poor, rural communities. As with venereal syphilis, the clinical manifestations of the endemic treponemal diseases are variable and can be broken down in to early stage and late stage disease. Current diagnostic techniques are unable to distinguish the different causative species but newer molecular techniques are now making this possible. Penicillin has long been considered the mainstay of treatment for the endemic treponemal diseases but the recent discovery that azithromycin is effective in the treatment of yaws has renewed interest in these most neglected of the NTDs, and raised hopes that global eradication may finally be possible.

The endemic treponematoses

The agents of human treponematoses include four closely related members of the genus Treponema: three subspecies of Treponema pallidum plus Treponema carateum. T. pallidum subsp. pallidum causes venereal syphilis, while T. pallidum subsp. pertenue, T. pallidum subsp. endemicum, and T. carateum are the agents of the endemic treponematoses yaws, bejel (or endemic syphilis), and pinta, respectively. All human treponematoses share remarkable similarities in pathogenesis and clinical manifestations, consistent with the high genetic and antigenic relatedness of their etiological agents. Distinctive features have been identified in terms of age of acquisition, most common mode of transmission, and capacity for invasion of the central nervous system and fetus, although the accuracy of these purported differences is debated among investigators and no biological basis for these differences has been identified to date. In 2012, the World Health Organization (WHO) officially set a goal for yaws eradication by 2020. This challenging but potentially feasible endeavor is favored by the adoption of oral azithromycin for mass treatment and the currently focused distribution of yaws and endemic treponematoses and has revived global interest in these fascinating diseases and their causative agents.

Secondary yaws: an endemic treponemal infection

Although yaws is rare in developed countries, as worldwide travel has become commonplace, it is essential to recognize this condition when evaluating patients who traveled from endemic regions. Herein, we discuss a case of secondary yaws presenting as extensive expanding annular lesions to raise awareness of this condition.

Cutaneous manifestations of syphilis : recognition and management

After a marked decline in the number of syphilis cases in the context of AIDS prevention campaigns, a significant increase has been observed in states of the former Soviet Union since 1994. In recent years, outbreaks have also been reported in the US, Canada, and several European countries. The current epidemic in the US and in different parts of Europe has largely involved men who have sex with men, many of whom are infected with HIV. Since a misdiagnosis of syphilis can have serious consequences for the patient and also for pregnancies and newborns, clinicians should be aware of the many manifestations of syphilis and difficulties in the diagnosis and management of the disease. Younger clinicians in particular are no longer familiar with the diverse clinical symptoms and the complex diagnostics of syphilis. Patients co-infected with HIV may present with atypical clinical manifestations and laboratory test results. Furthermore, through its association with an increased risk of HIV infection, syphilis has acquired a new potential for morbidity and mortality, and the diagnosis of syphilis should be routinely considered in patients with uveitis, sudden deafness, aortic thoracic aneurysm, or pregnancy. Only a minority of syphilis infections are detected in the primary stage. This may be because of atypical locations and, occasionally, atypical morphology of the lesions; however, it may also be because of the difficulty of detecting the pathogen. In the secondary stage, which is clinically extremely diverse, the diagnosis is confirmed serologically. There is a need for increased awareness of the symptoms and signs of acute infections, together with a willingness to consider the diagnosis of syphilis in patients with vague symptoms. An increasing number of diagnostic tests (both specific and nonspecific) are now available. However, in the absence of clinical symptoms or in cases with a low titer or inconsistent test results, diagnosis of syphilis can be difficult or even impossible. Treatment and follow-up should follow current guidelines designed for the involved area. In this article, the cutaneous manifestations of syphilis and their diagnostic and therapeutic management are described in detail.

Endemic treponematosis: review and update

Despite major efforts to eradicate these disorders, yaws, bejel, and pinta (endemic treponematosis) remain serious health issues in many regions of the world. Aside from prominent skin manifestations, these diseases may also lead to significant osseous, neurologic, and ophthalmologic complications. Although progress has been made in differentiating the causative species in a research setting, a simple, specific, and sensitive diagnostic test remains elusive. Parenteral penicillin, in appropriate dosage, is the treatment of choice; alternative antibiotics such as tetracycline and erythromycin may also be effective.

Rib lesions in a prehistoric Puebloan sample from southwestern Colorado

An unusually high frequency of periosteal lesions of visceral rib surfaces was observed in a small, prehistoric skeletal series from southwestern Colorado. Lesions of this type have been concordant with pulmonary tuberculosis in three studies of human skeletal collections with known cause of death, and in a recent clinical investigation of rib dimensions in living patients with lung disorders. Diseases such as pneumonia and actinomycosis have also been found to cause these lesions, but in much lower frequencies. Archaeological evidence suggests that Puebloan farmers of Sleeping Ute Mountain's southern piedmont, from which the sample is drawn, endured unusually harsh environmental conditions punctuated by severe drought and exacerbated by escalating warfare. It is argued here that these environmental stressors increased susceptibility to an opportunistic respiratory infection reminiscent of tuberculosis, and possibly also some form of pneumonia, resulting in high rates of active disease previously noted only in historic Puebloan peoples.

Skeletal evidence of probable treponemal infection in free-ranging African apes

The prevalence and patterning of inflammatory lesions of the skeleton were investigated in samples of chimpanzees (Pan troglodytes troglodytes) and gorillas (Gorilla gorilla gorilla) curated at the Powell-Cotton Museum, Birchington, UK. One hundred and two chimpanzees (42 adults and 60 subadults) and 126 gorillas (50 adults and 76 subadults) comprise the samples. Twenty per cent of chimpanzees and 14% of gorillas were affected with a disseminated inflammatory skeletal condition caused by infection. The lesions appear to have originated as localized patches of new bone deposition on the surface of long bones and to have progressed to infection of the bone cortex and marrow. Although female prevalence of involvement exceeds that of males in both species, the differences are not statistically significant. The age distribution of affected animals indicates that the disease began in some animals as early as 2 yr of age. Given the skeletal and demographic prevalence and patterning of the lesions as well as the ecology and behavior of these animals, the most likely diagnosis of the condition is a yaws-like treponemal infection.

Lymphadenopathy

Lymphadenopathy can occur in any age group, in symptomatic or asymptomatic patients, and in a single site or at multiple sites. Lymphadenopathy is associated with numerous disorders. An abnormal lymph node may be observed or palpated by the patient, found by a health care worker, or discovered through radiologic evaluation. Lymphadenopathy may be a part of a complex case presentation, or the clinical cause may be straightforward. Patients with potentially curable malignant disorders may have lymphadenopathy as the first sign of their disease. This review of lymphadenopathy summarizes general considerations, discusses which patients might be considered for biopsy, reviews which nodes are most likely to be diagnostic, outlines initial diagnostic considerations on a region-by-region basis, and reviews a broad differential diagnosis for adenopathy.

rpoB gene analysis as a novel strategy for identification of spirochetes from the genera Borrelia, Treponema, and Leptospira

Spirochetes are emerging pathogens for which culture and identification are partly unresolved. In fact, 16S rRNA-based sequencing is by far the most widely used PCR methodology that is able to detect such uncultivable pathogens. However, this assay actually has some limitations linked to potential problems of contamination, which hampers diagnosis. To circumvent this, we have devised a simple PCR strategy involving targeting of the gene encoding the RNA polymerase beta subunit (rpoB), a highly conserved enzyme. The complete sequence of the Leptospira biflexa (serovar patoc) rpoB gene was determined and compared with the published sequences for Borrelia burgdorferi and Treponema pallidum. From the resulting analysis, degenerate nucleotide primers were designed and tested for their ability to amplify a portion of the rpoB gene from various spirochetes. Using two different pairs of these primers, we succeeded in obtaining specific rpoB-amplified fragments for all members of the genera Leptospira, Treponema, and Borrelia tested and no other bacteria. Our findings may have significant implications for the development of a new tool for the identification of spirochetes, especially if clinical samples are contaminated or when the infecting strain is uncultivable.

Diagnosis of neurosyphilis: appraisal of clinical caseload

OBJECTIVES

To review the management of a cohort of patients with positive treponemal serology and psychiatric and/or neurological disorders.

METHODS

A retrospective case note review of 172 patients with positive treponemal serology attending the Patrick Clement's Clinic, Central Middlesex Hospital between December 1990 and November 1995 was performed.

RESULTS

101 men and 71 women were new attenders diagnosed with positive treponemal serology. A neurological problem was identified in 27 patients (12 women and 15 men) with psychiatric and/or neurological disorders, of whom 20 (six women and 14 men) underwent investigation of the cerebrospinal fluid (CSF). With the medical history and results of CSF-RPR and FTA tests, white cell count (WCC), and total protein level in the CSF, 10 patients (eight men and two women) were diagnosed with likely neurosyphilis and 17 with neurological disorders not thought to be caused by syphilis. The clinical features in those having neurosyphilis were sensorineural hearing loss (n = 5) and tabes dorsalis (n = 5). In the seven patients diagnosed with neurosyphilis who underwent CSF examination one patient had a reactive CSF-FTA, elevated protein, and elevated WCC; one patient had a reactive CSF-FTA and RPR with elevated protein; the total protein only was elevated in three cases and the WCC elevated in one case. Nine of the 10 patients with neurosyphilis received adequate neurosyphilitic treatment; one patient was lost to follow up.

CONCLUSIONS

The management of patients with positive treponemal serology and psychiatric and/or neurological disorders was consistent. Patients with suspected neurosyphilis or patients with neurological signs compatible with neurosyphilis (who did not undergo CSF examination) were treated with adequate neurosyphilitic therapy.

Lichen sclerosus

Lichen sclerosus, usually appearing in the dermatologic literature under the names of lichen sclerosus et atrophicus, balanitis xerotica obliterans, and kraurosis vulvae, is an inflammatory disease with a multifactorial origin. A past association of lichen sclerosus and genital squamous cell carcinoma is not as close as once thought. Once considered primarily a surgical problem, especially when the genitals were involved, lichen sclerosus will respond to a variety of systemic and topical therapies.