Fluorescent Treponemal Antibody Test Research Articles

S3185 The Great Imitator Spares No Organ: A Case of Syphilitic Hepatitis in an Immunocompetent Patient

Introduction: Syphilis, infamously known as the “great imitator,” is an infectious disease caused by the spirochete Treponema pallidum and can affect many organs. Though uncommon, syphilis can also affect the liver, often manifesting as elevated liver enzymes. Herein we describe the case of a 48-year-old immunocompetent male who was found to have a syphilis-induced acute liver injury. Case Description/Methods: A 48-year-old male presented with a two-week history of dry cough, fever, anorexia, and sore throat. He initially presented to an outside hospital where he was diagnosed with community-acquired pneumonia and discharged on amoxicillin-clavulanate. Given poor improvement in symptoms, he presented to our emergency department several days later and noted additional symptoms of headache, blurry vision, and rash. On admission, liver enzymes were elevated (Table 1), and a mild maculopapular rash was noted on his trunk and extremities. Clinical findings and liver injury were attributed to a drug injury in the setting of recent amoxicillin-clavulanate use. However, the liver injury persisted, prompting additional evaluation. Acute and chronic liver serology tests were unrevealing except for a positive anti-mitochondrial antibody, 44 units, and anti-nuclear antibodies, titers of 1:160. Syphilis screen with rapid plasma reagin was reactive with a titer of 1:32. Given neurological symptoms, a lumbar puncture was performed and revealed a reactive fluorescent treponemal antibody test absorption test. The patient was diagnosed with secondary syphilis complicated by neurosyphilis and syphilitic hepatitis. The patient completed a two-week course of intravenous penicillin with complete resolution in symptoms. After initiation of penicillin, the patient's liver chemistries downtrended and normalized after treatment, confirming the diagnosis of syphilitic hepatitis. Discussion: Syphilitic hepatitis is an uncommon manifestation of syphilis. Suspicion should be raised in patients with elevated liver chemistries, in particular cholestatic pattern, who also have manifestations such as maculopapular rash, low grade fever, arthralgias, headache, and changes in vision. This case highlights the importance of maintaining a broad differential and avoiding anchoring bias when approaching elevated liver chemistries. Table 1. - Liver Function Tests Baseline Outside Hospital Presentation Week 1 Week 3 Alkaline phosphatase (IU/L) 78 1126 1118 997 437 ALT (IU/L) 14 225 231 224 53 AST (IU/L) 19 130 154 139 37 Total bilirubin (mg/dL) 0.8 1.9 4.3 2.0 0.9

ORAL SECONDARY SYPHILIS IN PEOPLE LIVING WITH HIV: A 16-YEAR EXPERIENCE IN MEXICO CITY

Background The increase in syphilis rates worldwide, particularly in people living with HIV (PLWH), as well as the challenging diagnosis that secondary syphilis represents, make essential the accurate recognition of its manifestations, particularly in easy-access sites like the oral mucosa. Objective To describe the clinicopathologic spectrum of oral secondary syphilis (OSS) in PLWH. Methods A cross-sectional and descriptive study that included PLWH with OSS from 3 HIV referral centers in Mexico City (2004-2020). Demographic and clinical data were obtained. A comprehensive oral examination was done. OSS was diagnosed following established criteria. Histopathologic/cytological procedures were performed to rule out specific oral lesions. In all patients, Venereal Disease Research Laboratory tests were assessed and, if possible, a confirmatory fluorescent treponemal antibody test or biopsy was performed. Statistical analysis was performed using SPSS v25. Results Forty-seven PLWH with OSS (97.8% male, median age: 32 years, 63.8% with acquired immunodeficiency syndrome) were included. Thirty-five were receiving combination antiretroviral therapy (74.5%; median of 1146 [Q1-Q3: 337.5-1971] days) with a median CD4+ count of 385 (Q1-Q3: 223-664) cells/mm3 and a Log10 HIV viral load of 4.1 (Q1-Q3: 3.7-5.3) copies/mL. Forty had a complete clinical-serological diagnosis (85.1%; 17 had histopathologic confirmation) and 7 had a clinical-histopathologic diagnosis. Twenty-nine individuals presented 1 lesion (61.7%), and mucous patch was the most common type mainly on oropharyngeal mucosa, followed by ulcers and macular lesions. Ten patients presented maculopapular dermatosis (21.3%). Conclusions In PLWH, oral lesions, particularly mucous patch and/or ulcers on the oral and oropharyngeal mucosa, must alert specialists to consider a diagnosis of syphilis and perform a comprehensive panel of confirmatory tests.

High frequency of neurosyphilis in HIV-positive patients diagnosed with early syphilis.

Syphilis is an infection frequently seen with HIV, and European guidelines on the management of syphilis suggest that HIV-infected patients may have an increased risk of early neurological involvement, sometimes asymptomatic. Recent study shows a relationship between neurosyphilis and cerebrospinal fluid (CSF) HIV viral load (VL), which in turn may be associated with subsequent neurocognitive decline. The aim of the study was estimation of the frequency of neurosyphilis among HIV-positive patients with early syphilis. The study included all patients diagnosed with early syphilis who had lumbar puncture performed in the years 2008-2012. Analysis included CSF parameters (serology, mononuclear cells, protein, glucose, chloride and lactate levels), CD4 count, serum VL and highly active antiretroviral therapy (HAART). Diagnosis of neurosyphilis was confirmed by CSF serology [positive fluorescent treponemal antibody and/or Venereal Disease Research Laboratory (VDRL) test(s)] and increased number of mononuclear cells. Statistical analysis included χ(2) tests with an accepted significance level of P < 0.05. Lumbar puncture was performed in 72 patients, all men, with median age 33 (interquartile range 11) years. Neurosyphilis was confirmed in 65 (90.28%) of the patients. No statistically significant association between CSF parameters and CD4 count was found. However, statistically significant associations were found only between pleocytosis and serum VL > 1000 HIV-1 RNA copies/mL (P = 0.0451), as well as HAART treatment (P = 0.0328). The proportion of confirmed neurosyphilis cases, also in patients with low serum VDRL titres, was very high. Considering the high proportion of patients who objected to having LP performed in the absence of neurological symptoms and the risk associated with this procedure, it may be preferable to use treatments with good CNS penetration in all HIV-positive patients with early syphilis.

An Unusual Case of Epigastric and Back Pain

A 63-year-old African woman immigrated to Europe presented to our hospital with increasing epigastric pain radiating to back, unresponsive to proton-pump inhibitors, lasting for a week. There was no nausea, vomiting, diarrhea, or fever. History was positive for diabetes mellitus, hypertension, and previously treated pulmonary tuberculosis. On examination, the patient was afebrile, and there was no lymphadenopathy. Amylase and lipase levels were normal, whereas erythrocyte sedimentation rate (120 mm/h) and C-reactive protein (14 mg/dL) were increased. Superior endoscopy showed normal findings; abdominal ultrasound was negative. Computed tomography (CT) angiography revealed a 10×23-mm saccular aneurysm of thoracic aorta (D9 level) with localized dissection and thickening of the aortic wall (Figure 1). There was lymph node enlargement at hilum and along bronchopulmonary, thoracic, and lumbosacral chains. Apical pleural thickness and …

Clinical Spectrum of Oral Secondary Syphilis in HIV-Infected Patients.

Background. Oral lesions may constitute the first clinical manifestation in secondary syphilis, but detailed descriptions in HIV-infected individuals are scarce. Objective. To describe the clinical characteristics of oral secondary syphilis in HIV-infected patients and its relevance in the early diagnosis of syphilis. Methods. Twenty HIV/AIDS adult subjects with oral secondary syphilis lesions presenting at two HIV/AIDS referral centers in Mexico City (2003–2011) are described. An oral examination was performed by specialists in oral pathology and medicine; when possible, a punch biopsy was done, and Warthin-Starry stain and immunohistochemistry were completed. Intraoral herpes virus infection and erythematous candidosis were ruled out by cytological analysis. Diagnosis of oral syphilis was confirmed with positive nontreponemal test (VDRL), and, if possible, fluorescent treponemal antibody test. Results. Twenty male patients (median age 31.5, 21–59 years) with oral secondary syphilis lesions were included. Oral lesions were the first clinical sign of syphilis in 16 (80%) cases. Mucous patch was the most common oral manifestation (17, 85.5%), followed by shallow ulcers (2, 10%) and macular lesions (1, 5%). Conclusions. Due to the recent rise in HIV-syphilis coinfection, dental and medical practitioners should consider secondary syphilis in the differential diagnosis of oral lesions, particularly in HIV-infected patients.

Secondary syphilis: a multisystem disease not to be forgotten

A42-year-old homosexual man presented with a 3-month history of painful mouth ulcers and a hyperkeratotic, erythematous scaly rash affecting his palms and soles (Figure 1). He also had a 2-month history of bilateral anterior tibial pain, balanitis and a panuveitis. There was a recent history of a non-specific urethritis and a past history of shingles. In addition to the rash affecting his palms and soles, he had facial seborrhoeic dermatitis, mucosal ulceration with leukoplakia, and a balanitis with phimosis. A tender firm lump was noted over his left anterior shin. He was apyrexial and there was no lymphadenopathy or hepatosplenomegaly. Routine investigations revealed a raised erythrocyte sedimentation rate of 42 mm/h, associated with a polyclonal rise of immunoglobulins with a normal full blood count and C-reactive protein. A plantar skin biopsy showed numerous plasma cells in addition to lymphocytes within the papillary dermis (Figure 2). A Warthin–Starry stain for bacteria was negative. At the same time as the skin biopsy his vision worsened with bilateral mid-peripheral retinitis in addition to panuveitis. The skin biopsy showing numerous plasma cells and the mid-peripheral distribution of the retinitis were highly suggestive of secondary syphilis. The diagnosis of secondary syphilis was confirmed by a positive venereal disease research laboratory (VDRL) titre of 1:256, in association with a positive fluorescent treponemal antibody (FTA) test and treponema pallidum haemagglutination assay. He was also found to be positive for human immunodeficiency virus with a CD4 (t-helper cell) count of 145 × 106/litre (10.5%), and a viral load of 115 305 copies/ml. X-rays of his tibial bones revealed bilateral lytic cortical lesions, in keeping with a syphilitic osteitis. The firm tender lump over his left shin corresponded to a cortical lesion with a marked periosteal reaction (Figure 3). He was given a 10-day course of high-dose intravenous benzylpenicillin, after which his skin and mucosal lesions had almost resolved. The initial ocular inflammatory reaction settled quickly but visual acuity deteriorated 2 days after the commencement of penicillin, thought to result from an intraocular Jarisch–Herxheimer reaction. This complication was treated with a tapering dose of oral prednisolone, starting at a dose of 60 mg/day. His visual acuity subsequently returned to normal leaving a residual typical ‘salt and pepper’ scarring in the fundus (Figure 4).

Secondary syphilis simulating oral hairy leukoplakia

We describe a case of secondary syphilis of the tongue in which the main clinical presentation of the disease was similar to oral hairy leukoplakia. In a man who was HIV seronegative, the first symptom was a dryness of the throat followed by a feeling of foreign body in the tongue. Lesions were painful without cutaneous manifestations of secondary syphilis. IgM–fluorescent treponemal antibody test and typical serologic parameters promptly led to the diagnosis of secondary syphilis. We initiated an appropriate antibiotic therapy using benzathine penicillin, which induced healing of the tongue lesions. The differential diagnosis of this lesion may include oral squamous carcinoma, leukoplakia, candidosis, lichen planus, and, especially, hairy oral leukoplakia. This case report emphasizes the importance of considering secondary syphilis in the differential diagnosis of hairy oral leukoplakia. Depending on the clinical picture, the possibility of syphilis should not be overlooked in the differential diagnosis of many diseases of the oral mucosa.

Efficacy of serologic testing in asymmetric sensorineural hearing loss

Purpose: The goal of this study was to determine the efficacy of a detailed questionnaire, auditory brain stem response testing (ABR), MRI, and an extensive battery of serologic tests in diagnosing asymmetric sensorineural hearing loss (ASNHL). Methods And Material: Patients with audiograms demonstrating ASNHL of 10 dB or greater in 2 consecutive frequencies or 15 dB in any 1 frequency between 250 and 6000 Hz were asked to participate. Patients underwent MRI scanning of the cerebellopontine angle, internal auditory canals, and posterior fossa with gadolinium contrast, ABR, and an extensive battery of tests. The causative diagnosis was made by the individual clinician based on each patient’s history, physical examination, and test results. Results: Forty-five patients completed the study. A review of the data confirmed the utility of a detailed history and physical examination, MRI, and fluorescent treponemal antibody test in all cases. Erythrocyte sedimentation rate, glycosylated hemoglobin, Lyme antibody titers, and total hemolytic component (CH50) were helpful in selected cases. Thyroid function testing, complete blood count, Sequential Multiple Analysis-7, prothrombin time/partial thromboplastin time, lipid profile, and ABR were of no value in these patients. Conclusion: A careful history and physical examination, MRI, and fluorescent treponemal antibody test should be performed for the evaluation of all patients with ASNHL; however, more extensive serologic testing, including sedimentation rate, glycosylated hemoglobin, Lyme antibody titers, and CH50, should be selectively performed, based on a suggestive history or suspicious physical findings. (Otolaryngol Head Neck Surg 2000;122:469-76.)

Efficacy of serologic testing in asymmetric sensorineural hearing loss.

The goal of this study was to determine the efficacy of a detailed questionnaire, auditory brain stem response testing (ABR), MRI, and an extensive battery of serologic tests in diagnosing asymmetric sensorineural hearing loss (ASNHL). Patients with audiograms demonstrating ASNHL of 10 dB or greater in 2 consecutive frequencies or 15 dB in any 1 frequency between 250 and 6000 Hz were asked to participate. Patients underwent MRI scanning of the cerebellopontine angle, internal auditory canals, and posterior fossa with gadolinium contrast, ABR, and an extensive battery of tests. The causative diagnosis was made by the individual clinician based on each patient's history, physical examination, and test results. Forty-five patients completed the study. A review of the data confirmed the utility of a detailed history and physical examination, MRI, and fluorescent treponemal antibody test in all cases. Erythrocyte sedimentation rate, glycosylated hemoglobin, Lyme antibody titers, and total hemolytic component (CH50) were helpful in selected cases. Thyroid function testing, complete blood count, Sequential Multiple Analysis-7, prothrombin time/partial thromboplastin time, lipid profile, and ABR were of no value in these patients. A careful history and physical examination, MRI, and fluorescent treponemal antibody test should be performed for the evaluation of all patients with ASNHL; however, more extensive serologic testing, including sedimentation rate, glycosylated hemoglobin, Lyme antibody titers, and CH50, should be selectively performed, based on a suggestive history or suspicious physical findings.

Effect of passive immunization with purified specific or cross-reacting immunoglobulin G antibodies against Treponema pallidum on the course of infection in guinea pigs.

Whole immune serum or highly purified immunoglobulin G (IgG) antibodies to Treponema pallidum exhaustively adsorbed with three strains of nonpathogenic treponemes (TPI-IgG) were used for passive immunization of inbred strain 2 guinea pigs before and after intradermal challenge with 3.4 x 10(7) virulent T. pallidum Nichols organisms. Before challenge, control animals received a similarly purified IgG fraction containing either a cocktail of antibodies against three nonpathogenic treponemes (NPTI-IgG) or IgG prepared from normal guinea pig serum (NGPS-IgG). The purified fractions contained both IgG1 and IgG2 isotypes. The antibody levels (detected by fluorescent treponemal antibody test and enzyme-linked immunosorbent assay) and molecular specificities (immunoblot) of sera obtained from recipient animals before infection reflected those of the purified fractions used for immunization. Three protocols of passive immunization were used. Whole immune serum containing specific and cross-reacting antibodies afforded better protection than TPI-IgG even though asymptomatic animals were not fully protected. A single intradermal injection (0.1 ml) of TPI-IgG or NPTI-IgG into one hind leg 22 h before infection at the same site provided relatively higher protection than multiple intravenous injections (total, 15 ml) of the respective individual preparations. Since purified NGPS-IgG injected in the same animals, into the opposite hind leg, failed to protect against the challenging infection, it is reasonable to assume that specific and cross-reacting antitreponemal antibodies of the IgG1 subclass, which in guinea pigs are homocytotropic, play a relevant role in local protection.

Experimental congenital syphilis: guinea pig model

Neonates born to female guinea pigs of either a highly susceptible (C4D) or a resistant (Albany) strain, infected prior to or during pregnancy with a single dose of Treponema pallidum, showed in their sera from the first day of life immunoglobulin M (IgM) antibodies to T. pallidum, circulating immune complexes consisting of IgM antibodies and treponemal antigens, and IgM rheumatoid factor. Although the animals were asymptomatic for a 6-month observation period, several lines of evidence indicated that they were infected in utero. Molecular analysis of whole sera, purified serum IgM fraction, or dissociated immune complexes demonstrated IgM reactivity against one (47 kDa) or more of several T. pallidum peptides (15, 17, 37, 42, 45, and 87 kDa) recognized as integral membrane components. Sequential analysis of the neonates' sera by immunoblot and enzyme-linked immunosorbent assay, using alcohol-treated T. pallidum, T. phagedenis biotype Reiter, and T. vincentii, demonstrated early IgM antibodies followed 3 to 4 months later by IgG2- and IgG1-specific antibodies to T. pallidum. Moreover, an infectivity test done in five rabbits with pooled tissue extracts prepared from liveborn or stillborn animals evoked a seroconversion in two rabbits (reactive Venereal Disease Research Laboratory and fluorescent treponemal antibody tests), suggesting the presence of T. pallidum in the organs. Sera from neonates born to either T. phagedenis biotype Reiter-injected mothers or three normal pregnant females were all serologically negative. The model offers new possibilities for exploration of factors responsible for asymptomatic infection often observed in human congenital syphilis.

Experimental infection of inbred guinea pigs with Treponema pallidum: development of lesions and formation of antibodies.

Inbred strain 2 and strain 13 guinea pigs were infected intradermally in the hind legs with different numbers of the virulent Nichols strain of Treponema pallidum. About 91% of the animals developed clearly visible lesions after being injected with 5 X 10(6) to 10 X 10(6) treponemes. T pallidum organisms could be isolated from skin lesions at various stages after infection. Infected animals were monitored for the production of specific treponemal and non-specific cardiolipin antibodies by the fluorescent treponemal antibody (FTA) and microhaemagglutination (MHA-TP) tests and the rapid plasma reagin (RPR) card test. Low levels of specific antibodies could be detected by both FTA and MHA-TP tests from three to four weeks after infection. Maximum titres of treponemal antibody generally occurred after week 6 and persisted for several more months. These peak titres ranged from 1/40 to 1/80 in the FTA test and 1/160 to 1/320 in the MHA-TP test. During the same period infected guinea pigs, unlike rabbits with syphilis, did not produce detectable quantities of antibodies against cardiolipin.

Rapidly Progressive Glomerulonephritis in a Patient With Syphilis. Identification of Antitreponemal Antibody and Treponemal Antigen in Renal Tissue

A 37-year-old man presented with biopsy-proved rapidly progressive glomerulonephritis and a strongly positive fluorescent treponemal antibody result. The patient was treated with hemodialysis, plasmapheresis, methylprednisolone, and penicillin, with rapid improvement and stabilization of renal function. Antibody was eluted from the frozen renal tissue and demonstrated a strongly positive reaction to the treponemal antigen when used in the fluorescent treponemal antibody test. In addition, when specific rabbit antitreponemal antiserum was applied to the frozen renal sections, there was a strongly positive reaction. Although syphilis has been associated with membranous glomerulopathy and post-infectious glomerulonephritis, this appears to be the first case of latent syphilis in which rapidly progressive glomerulonephritis has been identified. The presence within the glomeruli of treponemal antigen and antitreponemal antibody supports the association of these two entities.

Rapidly progressive glomerulonephritis in a patient with syphilis: Identification of antitreponemal antibody and treponemal antigen in renal tissue

A 37-year-old man presented with biopsy-proved rapidly progressive glomerulonephritis and a strongly positive fluorescent treponemal antibody result. The patient was treated with hemodialysis, plasmapheresis, methylprednisolone, and penicillin, with rapid improvement and stabilization of renal function. Antibody was eluted from the frozen renal tissue and demonstrated a strongly positive reaction to the treponemal antigen when used in the fluorescent treponemal antibody test. In addition, when specific rabbit antitreponemal antiserum was applied to the frozen renal sections, there was a strongly positive reaction. Although syphilis has been associated with membranous glomerulopathy and post-infectious glomerulonephritis, this appears to be the first case of latent syphilis in which rapidly progressive glomerulonephritis has been identified. The presence within the glomeruli of treponemal antigen and antitreponemal antibody supports the association of these two entities.

Solid-phase fluoroimmunoassay for treponemal antibody.

An objective, solid-phase fluoroimmunoassay for treponemal antibody was developed with a lysate of virulent Treponema pallidum (Nichols strain) adsorbed on cellulose acetate disks. A probe containing both the antigen and control disks is inserted successively into a serum specimen dilution, a buffer rinse, fluoroscein isothiocyanate-conjugated goat anti-human immunoglobulin G, and a second buffer rinse. Fluorescence signal units are measured with a fluorometer. To establish test calibration curves, the corrected fluorescence values (antigen disk minus control) of reference sera are plotted against indirect fluorescent treponemal antibody test titers. The corrected fluorescence values obtained for 62 sera reactive in the fluorescent treponemal antibody absorption test ranged from 64 to 178; values for 66 nonreactive sera ranged from 20 to 46. Thus, the solid-phase fluoroimmunoassay for treponemal antibody clearly separated specimens from patients with documented primary, secondary, or latent disease from fluorescent treponemal antibody absorption-nonreactive sera. The test is technically simple and produces an objective quantitative result.

Diagnosis of neurosyphilis by examination of the cerebrospinal fluid.

Thirty-six patients with reactive results in the cerebrospinal fluid to the Treponema pallidum haemagglutination assay (CSF-TPHA) were investigated by further serological tests for confirmation of active neurosyphilis. The results of the TPHA and fluorescent treponemal antibody tests were reactive in all CSF samples from patients with acute untreated neurosyphilis and from most patients with late latent syphilis but no signs of involvement of the central nervous system. The demonstration of 19S-IgM antibodies against Treponema pallidum in the CSF was a better indication of activity of the disease than the Venereal Disease Research Laboratory test. Ten of 11 patients with untreated acute neurosyphilis had reactive results in the solid-phase haemadsorption test for CSF-IgM (CSF-IgM-SPHA test). The TPHA index, which relates the CSF-TPHA titre to the albumin quotient and thus excludes errors from disturbed function of the blood-brain barrier, was above 100 in all but one of the patients with acute neurosyphilis but below 100 after treatment. Patients with late latent syphilis and without CNS signs had TPHA indices below 5. Thus a nonreactive CSF-TPHA test result excludes neurosyphilis but reactive CSF-IgM-SPHA results and TPHA indices above 100 strongly indicative active disease.

Non-specific positive test results to syphilis in dermatological diseases.

Sera from 3028 patients attending a dermatological clinic were examined by the fluorescent treponemal antibody (FTA) test, the fluorescent antibody-absorbed (FTA-ABS) test, the Venereal Disease Research Laboratory (VDRL) test, and Kolmer's test. Eleven cases of late syphilis were found. Sera from 63 (2.08%) of the remaining 3017 patients showed non-specific results; these were found more frequently in patients with pyodermas, neoplasms, acne, mycoses, crural ulceration, and psoriasis than in those with other diseases. No non-specific results were observed in patients with bullous skin diseases and only a few in patients with viral skin diseases and chronic lupus erythematosus. The test producing the most non-specific results was the FTA test, followed by the FTA-ABS test, the VDRL test, and Kolmer's test.

Evaluation of microhaemagglutination assay to determine treponemal antibodies in CSF.

The microhaemagglutination assay for Treponema pallidum antibodies (MHA:TP-CSF), the Veneral Disease Research Laboratory (VDRL-CSF), and the fluorescent treponemal antibody (FTA-CSF) tests were used to detect treponemal antibodies in 3157 samples of cerebrospinal fluid from patients with syphilis, with neurological, metabolic, or immunological disorders, and with undetermined diagnoses. An agreement of 99.5% between the results of the MHA:TP-CSF and FTA-CSF tests was obtained for all the CSF samples whereas that of only 95.5% was obtained for samples from the known case of syphilis. The MHA:TP-CSF test is simple, economical, rapid, and specific but not as sensitive as the FTA-CSF test.

The CSF‐FTA test and the significance of blood contamination

Although the fluorescent treponemal antibody absorption (FTA-ABS) test has found wide application in the diagnosis of syphilis, the cerebrospinal fluid fluorescent treponemal antibody (CSF-FTA) test is still controversial in the diagnosis of neurosyphilis. We found the CSF-FTA test extremely sensitive to contamination with FTA-ABS-reactive blood at concentrations in CSF that could not be detected by visual inspection. Interpretation of a reactive test should be made with caution if red cells are present in CSF.

Specificity of the FTA-ABS and TPHA tests during pregnancy.

In order to determine whether pregnancy influences the specificity of the fluorescent treponemal antibody absorption (FTA-ABS) and Treponema palidum haemagglutination assay (TPHA) tests, these tests, together with the quantitative fluorescent treponemal antibody (FTA) and Venereal Disease Research Laboratory (VDRL) tests, were carried out simultaneously on 2000 pregnant women who attended for compulsory prenatal screening. In only one patient (0.05% of the total investigated) was a positive result to the TPHA test obtained, the specificity of which it was impossibile to confirm. The FTA-ABS test gave a weakly reactive result of the borderline type but this was found to be non-specific in only four (0.2%) patients. The results of our investigations showed that the specificity of the FTA-ABS and the TPHA tests performed on pregnant women did not differ from the specificity of these tests when carried out on other population groups.