Performance of clinical, laboratory and imaging features for diagnosing spondyloarthritis-a systematic literature review and meta-analysis

OBJECTIVE

The Berlin algorithm was developed to help diagnosing axial spondyloarthritis (axSpA), but new studies suggest some features typical of SpA are less specific than previously assumed. Furthermore, evidence is lacking for other SpA subtypes (e.g. peripheral SpA). We aimed to review the evidence on the performance of SpA features for diagnosing each SpA subtype.

METHODS

Systematic literature review of studies reporting the diagnostic performance of ≥ 1 SpA feature in patients with suspected SpA. The external reference was the rheumatologist's diagnosis of SpA. Meta-analysis was performed, separately for each SpA subtype, to estimate pooled sensitivity, specificity, positive (LR+) and negative (LR-) likelihood ratios. Meta-regression assessed the effect of covariates (e.g. feature's prevalence) on each feature's performance.

RESULTS

Of 13 844 articles screened, 46 were included. Sacroiliitis on magnetic resonance imaging, damage on pelvic radiographs and elevated C-reactive protein (CRP) had the best balance between LR+ and LR- (LR + 3.9-17.0, LR- 0.5-0.7) for diagnosing axSpA. HLA-B27 had an LR+ lower than anticipated (LR + =3.1). Inflammatory back pain (IBP) had low LR + (LR+∼1), but substantially decreased the likelihood of axSpA when absent (LR-=0.3). Conversely, peripheral features and extra-musculoskeletal manifestations showed high LR + (LR+ 1.6-5.0), but were as common in axSpA as no-axSpA (LR-∼1). The specificity of most features was reduced in settings when these were highly prevalent. Limited data precluded a detailed analysis on diagnosing other SpA subtypes.

CONCLUSION

Imaging features and CRP have good diagnostic value for axSpA. However, the specificity of other features, especially HLA-B27 and IBP, is lower than previously known.

Necrotizing mesenteric vasculitis in systemic lupus erythematosus

Systemic lupus erythematosus (SLE) is a multisystemic autoimmune disorder which may affect the gastrointestinal system. Half of the patients with SLE experience gastrointestinal symptoms, with the most common being nausea, vomiting, anorexia, and abdominal pain. Mesenteric vasculitis is a severe and rare complication of SLE and one of the most frequent causes of severe acute abdominal pain. The authors present a case of a 57-year-old woman with SLE who was diagnosed with necrotizing mesenteric vasculitis following a urinary septic shock. The patient was treated with high-dose corticosteroid therapy and cyclophosphamide, with resolution of the clinical picture.

Cytomegalovirus and rheumatic diseases: cases-based review

Cytomegalovirus (CMV) infection is a common and typically benign disease in immunocompetent individuals. However, immunocompromised patients are at a greater risk of reactivation, leading to more severe outcomes. Patients with rheumatic diseases have a particularly high risk of opportunistic infections due to both the inherent immunosuppressive state conveyed by the disease itself and the use of potent immunosuppressant drugs, such as glucocorticoids, cyclophosphamide, and rituximab. Limited data are available regarding prophylactic or preemptive treatment of CMV infection in patients with rheumatic diseases. In this article the authors present two cases of rheumatic conditions complicated by CMV infection. The first case describes a patient with eosinophilic granulomatosis with polyangiitis, previously treated with glucocorticoids and cyclophosphamide, who developed CMV colitis with bowel perforation. The second case involves a woman with systemic lupus erythematosus who was diagnosed with CMV meningitis. Both cases reinforce the importance of establishing guidelines for surveillance and prophylaxis of CMV infection in these patients.

The idiopathic inflammatory myopathies module of the Rheumatic Diseases Portuguese Register

AIMS

To characterise the idiopathic inflammatory myopathies (IIM) module of the Rheumatic Diseases Portuguese Register (Reuma.pt/myositis) and the patients in its cohort.

METHODS

Reuma.pt is a web-based system with standardised patient files gathered in a registry. This was a multicentre open cohort study, including patients registered in Reuma.pt/myositis up to January 2022.

RESULTS

Reuma.pt/myositis was designed to record all relevant data in clinical practice and includes disease-specific diagnosis and classification criteria, clinical manifestations, immunological data, and disease activity scores. Two hundred eighty patients were included, 71.4% female, 89.4% Caucasian, with a median age at diagnosis and disease duration of 48.9 (33.6-59.3) and 5.3 (3.0-9.8) years. Patients were classified as having definite (N=57/118, 48.3%), likely (N=23/118, 19.5%), or possible (N=2/118, 1.7%) IIM by 2017 EULAR/ACR criteria. The most common disease subtypes were dermatomyositis (DM, N=122/280, 43.6%), polymyositis (N=59/280, 21.1%), and myositis in overlap syndromes (N=41/280, 14.6%). The most common symptoms were proximal muscle weakness (N=180/215, 83.7%) and arthralgia (N=127/249, 52.9%), and the most common clinical signs were Gottron's sign (N=75/184, 40.8%) and heliotrope rash (N=101/252, 40.1%). Organ involvement included lung (N=78/230, 33.9%) and heart (N=11/229, 4.8%) involvements. Most patients expressed myositis-specific (MSA, N=158/242, 65.3%) or myositis-associated (MAA, 112/242, 46.3%) antibodies. The most frequent were anti-SSA/SSB (N=70/231, 30.3%), anti-Jo1 (N=56/236, 23.7%), and anti-Mi2 (N=31/212, 14.6%). Most patients had a myopathic pattern on electromyogram (N=101/138, 73.2%), muscle oedema in magnetic resonance (N=33/62, 53.2%), and high CK (N=154/200, 55.0%) and aldolase levels (N=74/135, 54.8%). Cancer was found in 11/127 patients (8.7%), most commonly breast cancer (N=3/11, 27.3%). Most patients with cancer-associated myositis had DM (N=8/11, 72.7%) and expressed MSA (N=6/11) and/or MAA (N=3/11). The most used drugs were glucocorticoids (N=201/280, 71.8%), methotrexate (N=117/280, 41.8%), hydroxychloroquine (N=87/280, 31.1%), azathioprine (N=85/280, 30.4%), and mycophenolate mofetil (N=56/280, 20.0%). At the last follow-up, there was a median MMT8 of 150 (142-150), modified DAS skin of 0 (0-1), global VAS of 10 (0-50) mm, and HAQ of 0.125 (0.000-1.125).

CONCLUSIONS

Reuma.pt/myositis adequately captures the main features of inflammatory myopathies' patients, depicting, in this first report, a heterogeneous population with frequent muscle, joint, skin, and lung involvements.

Particularly severe form of refractory gastrointestinal involvement in systemic sclerosis

A woman with systemic sclerosis presents with a severe and rapidly progressive form of gastrointestinal involvement, mainly marked by recurrent refractory episodes of pseudo-obstruction, culminating in severe malnutrition and dependence of parenteral nutrition. The impact on her quality of life was extremely significant. As a last resort, she started intravenous immunoglobulin with progressive improvement of her symptoms, allowing for the reinstitution of oral diet and removal of parenteral nutrition. After more than 1 year, she maintains clinical stability. Systemic sclerosis has a heterogeneous phenotype, but gastrointestinal involvement is one of the most frequent. Severe manifestations are rare, but can lead to severe malnutrition and are associated with high morbidity and mortality rates. Their management is challenging, as the available treatments are still very limited. A better understanding of its pathophysiology, which seems to be unique, is essential to provide more effective treatments and improving quality of life.

Predictors of cardiac involvement in idiopathic inflammatory myopathies

Objectives

Idiopathic inflammatory myopathies (IIM) are a group of rare disorders that can affect the heart. This work aimed to find predictors of cardiac involvement in IIM.

Methods

Multicenter, open cohort study, including patients registered in the IIM module of the Rheumatic Diseases Portuguese Register (Reuma.pt/Myositis) until January 2022. Patients without cardiac involvement information were excluded. Myo(peri)carditis, dilated cardiomyopathy, conduction abnormalities, and/or premature coronary artery disease were considered.

Results

230 patients were included, 163 (70.9%) of whom were females. Thirteen patients (5.7%) had cardiac involvement. Compared with IIM patients without cardiac involvement, these patients had a lower bilateral manual muscle testing score (MMT) at the peak of muscle weakness [108.0 ± 55.0 vs 147.5 ± 22.0, p=0.008] and more frequently had oesophageal [6/12 (50.0%) vs 33/207 (15.9%), p=0.009] and lung [10/13 (76.9%) vs 68/216 (31.5%), p=0.001] involvements. Anti-SRP antibodies were more commonly identified in patients with cardiac involvement [3/11 (27.3%) vs 9/174 (5.2%), p=0.026]. In the multivariate analysis, positivity for anti-SRP antibodies (OR 104.3, 95% CI: 2.5-4277.8, p=0.014) was a predictor of cardiac involvement, regardless of sex, ethnicity, age at diagnosis, and lung involvement. Sensitivity analysis confirmed these results.

Conclusion

Anti-SRP antibodies were predictors of cardiac involvement in our cohort of IIM patients, irrespective of demographical characteristics and lung involvement. We suggest considering frequent screening for heart involvement in anti-SRP-positive IIM patients.

Arthritis or maybe not? Pachydermodactyly: the great mimicker of juvenile idiopathic arthritis

Arthritis in the paediatric population is the hallmark of many rheumatic inflammatory diseases, as well as other cutaneous, infectious, or neoplastic conditions. It can be quite devastating, whereby prompt recognition and treatment of these disorders are essential. However, arthritis can sometimes be mistaken for other cutaneous or genetic conditions leading to misdiagnosis and overtreatment. Pachydermodactyly is a rare and benign form of digital fibromatosis, usually manifested by swelling of the proximal interphalangeal joints of both hands, mimicking arthritis. The authors report a case of a 12-year-old boy with a one-year history of painless swelling of the proximal interphalangeal joints of both hands that was referred to the Paediatric Rheumatology department due to the suspicion of juvenile idiopathic arthritis. The diagnostic work-up was unremarkable, and the patient remained asymptomatic over an 18-month follow-up period. A diagnosis of pachydermodactyly was assumed and no treatment was introduced, given the benign nature of the disorder and absence of symptoms. Therefore, it was possible to safely discharge the patient from the Paediatric Rheumatology clinic.

Multiple Brown Tumors Secondary to Parathyroid Carcinoma: A Challenging Diagnosis

Parathyroid carcinoma is an extremely rare endocrine neoplasm that accounts for less than 1% of the cases of primary hyperparathyroidism (PHPT). Continuous exposure to high levels of parathyroid hormone (PTH) induces an increase in bone remodeling and patients may present with osteitis fibrosa cystica, which is characterized by subperiosteal resorption of the phalanges, diffuse osteopenia, salt and pepper appearance of the skull, bone cysts, and brown tumors. Brown tumors occur in less than 5% of all patients with any form of hyperparathyroidism. Due to similar clinical, radiographic, and histological appearance, differential diagnosis of brown tumors includes primary and secondary bone tumors. We report a case of a 67-year-old female diagnosed with multiple osteolytic lesions initially thought to be bone metastasis of thyroid carcinoma. Further work-up led to the diagnosis of brown tumors due to parathyroid carcinoma. We want to emphasize the inclusion of osteitis fibrosa cystic in the differential diagnosis of osteolytic lesions and the need to perform serum calcium and PTH measurements when investigating these lesions.

Clinical characterisation of a multicentre nationwide cohort of patients with antisynthetase syndrome

BACKGROUND

Antisynthetase syndrome (ASyS) is characterised by the association of inflammatory myopathy, interstitial lung disease (ILD), arthritis, Raynaud's phenomenon (RP) or mechanic's hands (MH), with the presence of anti-aminoacyl-tRNA-synthetase antibodies (anti-ARS). It has been suggested that different anti-ARS may be associated with distinct clinical pictures.

OBJECTIVE

To characterise the clinical and immunological features of a multicentric nationwide cohort of ASyS patients.

METHODS

This is a multicentre retrospective cohort study including patients with ASyS from nine Portuguese rheumatology centres. Data on patients' demographics, signs and symptoms, laboratory results, pulmonary imaging findings and treatment with immunomodulators were collected. Comparison between patients with different anti-ARS antibodies was made using the Chi-square test for categorical variables and Student's t-test or Man-Whitney test for continuous variables, considering anti-Jo1 positive patients as the reference group.

RESULTS

Seventy patients were included (70% female) with a median age in years at disease onset of 52 (15-75) years and median follow-up time of 3 years (range 0-32). The three most common clinical manifestations were ILD (n=53, 75.7%), followed by arthritis (n=43, 61.4%) and myositis (n=37, 52.9%). Forty-three patients were positive for anti-Jo1 (61.4%), 11 for anti-PL12 (15.7%), 10 for anti-PL7 (14.3%), 4 for anti-EJ (5.7%), and 2 for anti-OJ (2.9%) antibodies. Antibody co-positivity with anti-Ro52 antibodies was found in 15 patients (21.4%) and was more prevalent in anti-Jo1 patients. ILD prevalence was similar in the different anti-ARS subgroups, without statistically significant differences. Patients positive for anti-PL7 antibodies had significantly lower risk of presenting arthritis (p =< 0.05) and those positive for anti-PL-12 antibodies had a significantly lower risk of presenting myositis than the reference group of anti-Jo1 positive patients (p =< 0.05). RP was more frequently found in patients positive for anti-PL-12 than in anti-Jo1-positive patients (p =< 0.05). Malignancies were reported in four (5.7%) patients, none of whom were anti-Ro52-positive, and one of such patients had a double malignancy. Only three deaths were reported. Corticosteroids were the most frequently prescribed therapy and the use of immunosuppressive drugs was decided according to the type of predominant clinical manifestation.

CONCLUSION

The three most common clinical manifestations were ILD, followed by arthritis and myositis. Patients positive for anti-PL7 antibodies had significantly lower risk of presenting arthritis and those positive for anti-PL-12 antibodies had a significantly lower risk of presenting myositis than the reference group of anti-Jo1 positive patients. RP was more frequently found in patients positive for anti-PL-12 than in anti-Jo1-positive patients. Corticosteroids were the most frequently prescribed therapy. These results are generally concordant with data retrieved from international cohorts.

Sex differences in axial spondyloarthritis: data from a Portuguese spondyloarthritis cohort

BACKGROUND

Axial spondyloarthritis (axSpA), particularly ankylosing spondylitis was historically considered a male's disease and has been under-recognized in women. Emerging evidence reveals sex differences in pathophysiology, disease presentation and therapeutic efficacy.

OBJECTIVE

To identify differences between sexes in a Portuguese cohort of patients with axSpA regarding clinical manifestations, disease activity, functional capacity, patient related outcomes and presence of sacroiliitis on x-ray or magnetic resonance imaging.

METHODS

Patients with ≥18 years fulfilling the ASAS- Assessment of Spondyloarthritis International Society classification criteria for axSpA registered in the electronic Rheumatic Diseases Portuguese Register (Reuma.pt) were included in this multicentric cross-sectional study. Sociodemographic data, clinical features and imaging were collected from the first record in Reuma.pt. These variables were compared between sexes using Mann-Whitney test and Chi-Square test. Variables with a significant association with variable sex were considered in the multiple variable analysis to adjust the sex effect on the outcome variables. Statistical analysis was performed with R version 4.0.2 and p <0.05 was considered statistically significant.

RESULTS

A total of 1995 patients were included, 1114 (55.9%) men and 881 (44.1%) women. Men had an earlier disease onset (25.1 vs 28.4, p <0.001), were younger at diagnosis (26.9 vs 30.4, p<0.001) and were more frequently smokers (32.1% vs 15.7%, p <0.001). Comparing to women, men had worse Bath Ankylosing Spondylitis Metrological Index scores (4.0 vs 3.4, p<0.001), higher levels of C-Reactive Protein (10.5 vs 6.9 mg/L, p <0.001) and were more often Human Leukocyte Antigen-B27 positive (67.8% vs 54%, p <0.001). In contrast, women more frequently had inflammatory bowel disease (8.8% vs 4.9%, p =0.004), higher levels of erythrocyte sedimentation rate (25.0 vs 21.0mm/h, p=0.003) and worse patient-related outcomes- Bath Ankylosing Spondylitis Disease Activity Index (5.7 vs 4.5, p<0.001), Patient Global Assessment (60.0 vs 50.0, p <0.001) and fatigue (6.2 vs 5.0, p <0.001).

DISCUSSION

In this large multicentric study from a Portuguese axSpA cohort, we confirmed sex differences in patients with axSpA. This work brings awareness to these differences, resulting in less underdiagnosis and misdiagnosis, optimizing treatment strategies, and improving outcomes in axSpA.

Clinical features and outcome of 1054 patients with Systemic Sclerosis: analysis of Reuma.pt/SSc registry

BACKGROUND

Systemic sclerosis (SSc) is a rare connective tissue disorder with heterogeneous manifestations and outcomes. Besides differences in disease characteristics among distinct ethnic groups and geographical regions, several questions regarding the impact of the disease and the effectiveness of treatments remain unanswered. To address these questions, the Rheumatic Diseases Portuguese Register (Reuma.pt) launched a specific protocol for the prospective follow-up of SSc patients.

OBJECTIVES

To describe the baseline characteristics, disease subsets, treatments used and survival of SSc patients registered in Reuma.pt/SSc.

METHODS

Data from adult patients with SSc included in Reuma.pt up to November 2020 were analysed. Demographic features, SSc subsets, fulfilment of classification criteria, main clinical and immunological features, comorbidities, treatments used and survival data were described and compared between diffuse cutaneous (dc) and limited cutaneous (lc) disease subsets. Survival was calculated for patients included in Reuma.pt within the first two years of diagnosis.

RESULTS

In total, 1054 patients were included, 87.5% female, with a mean age at diagnosis of 52.7 +/- 14.8 years. The most common subset was lcSSc (56.3%), followed by dcSSc (17.5%), preclinical SSc (13%), overlap syndrome (9.8%) and SSc sine scleroderma (3.3%). Raynaud's phenomenon (93.4%) and skin thickening (76.9%) were the most frequently observed clinical manifestations. Gastrointestinal (62.8% versus 47.8%), pulmonary (59.5% versus 23%) and cardiac (12.8% versus 6.9%) involvements were significantly more prevalent in dcSSc than lcSSc. Ninety per-cent of patients were Antinuclear antibody positive, 52.5% were Anti-centromere antibody positive and 21% anti-topoisomerase positive, with significant differences between lcSSc and dcSSc. One-third of patients were treated with immunomodulators, 53.6% with vasodilators, 23% with glucocorticoids and 2.3% with biologics. During follow-up, 83 deaths (7.9%) were reported. The overall 1-, 2- and 5-year survivals were 98.0%, 96.8% and 92.6%, respectively, without significant differences between lcSSc and dcSSc.

CONCLUSION

Reuma.pt/SSc data highlights the importance of registries in improving knowledge about rare and complex diseases, such as SSc. Clinical features of Portuguese SSc patients are similar to those of other populations. In recently diagnosed patients, 5-year survival is over 92%. To the best of our knowledge, this is the first study showing that clinical features of Portuguese SSc are similar to those of other cohorts.

Direct tissue-sensing reprograms TLR4+ Tfh-like cells inflammatory profile in the joints of rheumatoid arthritis patients

CD4⁺ T cells mediate rheumatoid arthritis (RA) pathogenesis through both antibody-dependent and independent mechanisms. It remains unclear how synovial microenvironment impinges on CD4⁺ T cells pathogenic functions. Here, we identified a TLR4⁺ follicular helper T (Tfh) cell-like population present in the blood and expanded in synovial fluid. TLR4⁺ T cells possess a two-pronged pathogenic activity whereby direct TLR4⁺ engagement by endogenous ligands in the arthritic joint reprograms them from an IL-21 response, known to sponsor antibody production towards an IL-17 inflammatory program recognized to fuel tissue damage. Ex vivo, synovial fluid TLR4⁺ T cells produced IL-17, but not IL-21. Blocking TLR4 signaling with a specific inhibitor impaired IL-17 production in response to synovial fluid recognition. Mechanistically, we unveiled that T-cell HLA-DR regulates their TLR4 expression. TLR4⁺ T cells appear to uniquely reconcile an ability to promote systemic antibody production with a local synovial driven tissue damage program.

In order to identify how the synovial microenvironment impinges on CD4+ T cells pathogenic functions in Rheumatoid Arthritis (RA), Amaral-Silva examined RA patient blood and synovial fluif and identified the presence of a TLR4+ follicular helper T (Tfh) cell-like population. They provided mechanistic insight into how TLR4⁺ T cells uniquely reconcile an ability to promote systemic antibody production with a local synovial driven-tissue damage program.

Quantitation of human immunodeficiency virus type 2 DNA in peripheral blood mononuclear cells by using a quantitative-competitive PCR assay

A new quantitative-competitive PCR-based human immunodeficiency virus type 2 (HIV-2) proviral DNA assay (QC-PCR) was developed and used to determine the proviral load in HIV-2-infected individuals. Proviral load varied considerably, with means of 1,831 copies per 10(6) peripheral blood mononuclear cells for asymptomatic subjects (n = 19) and 2,587 for AIDS patients (n = 2). HIV-2 viral and proviral loads also varied significantly over time in asymptomatic patients. These data suggest that a high level of virus replication occurs throughout the asymptomatic phase of HIV-2 infection.

Virological and molecular demonstration of human immunodeficiency virus type 2 vertical transmission

To demonstrate that human immunodeficiency virus type 2 (HIV-2) mother-to-child transmission exists, HIV-2 isolates were obtained from both an asymptomatic mother (HIV-2 strain ARM), and her child (HIV-2 strain SAR), who had a diagnosis of AIDS. To determine their biological phenotype, primary isolates were used to infect various primary mononuclear cells and cell lines. HIV-2 ARM replicates in primary cells and Jurkat-tat, while HIV-2 SAR infects these cells plus SupT1, which led us to classify HIV-2 ARM as a slow/low virus and HIV-2 SAR as having an intermediate (slow/low-3) phenotype. Molecular analysis of the env region corresponding to gp125 was performed. Viral DNA was cloned, sequenced, and used to construct phylogenetic trees. The DNA sequence analysis demonstrated an overall nucleotide diversity of 7.6%. The results present evidence that the child's strain is more virulent than the mother's strain, which is in agreement with the immunodeficiency of the child. The phylogenetic trees that were constructed demonstrate that the two isolates cluster together, being closer to each other than to any other isolate described until now.

Multicenter evaluation of a fully automated screening test, VIDAS HIV 1 + 2, for antibodies to human immunodeficiency virus types 1 and 2

A multicenter study was done to evaluate the sensitivity, specificity, and efficiency of a new screening test for the simultaneous detection of human immunodeficiency virus type 1 and 2 (HIV-1 and HIV-2) antibodies. The VIDAS HIV 1 + 2 (bioMérieux, Marcy l'Etoile, France) is a fully automated enzyme-linked fluorescent immunoassay that uses synthetic peptides from immunodominant regions of gp41 of HIV-1 and gp36 of HIV-2 as antigens. A total of 2,984 samples were evaluated with this system in six different laboratories, and the results were compared to those obtained with other enzyme-linked immunosorbent assays. The VIDAS HIV 1 + 2 assay showed a very good performance in terms of sensitivity (100%) and specificity (99.6%), requiring minimal manipulation and short incubation time (32 min) to give results similar to or better than those of the other enzyme-linked immunosorbent assays used for screening.

Prevalence of HIV-2 infection in a family planning clinic in Lisbon

A significant proportion (10%) of notified AIDS cases in Portugal are due to HIV-2 infection as a result of the close connections of Portugal with Western African Countries (ex-Portuguese colonies) where there is a high HIV-2 seroprevalence. We conducted a seroepidemiological study of HIV-1 and HIV-2 infection in 1400 women attending family planning and antenatal clinics in a health centre in Lisbon with the objective of analysing whether there was evidence of HIV-2 spread in this population. The seroprevalence for HIV, as determined by ELISA and confirmed by Western Blot, was 0.42% (6 cases) and 50% of these were of HIV-2 infection. Analysis of the epidemiological inquiries reveals that out of the 6 seropositive cases, only one was a drug addict (HIV-1) and another a western African black woman (HIV-2). The other 4 cases (2 HIV-2 and 2 HIV-1) were white Portuguese women with no history of travelling to Africa or previous blood transfusions, and the only risk factor was a history of multiple sexual partners (in 3 out of 4).

[Prevalence of HIV1 and HIV2 infection in women living in an area of Lisboa City]

A seroprevalence study of HIV1 and HIV2 infection in women attending a Family Planning and an Antenatal Clinic was done in an area of the city of Lisbon where 7% of the population is of African origin. The protocol of study was of non linked type although with the possibility of collecting a second sample of blood for confirmation of results. Epidemiological, social and clinical data were collected from 1390 women and this was followed by the collection of a blood sample for the seroepidemiological study of HIV1 and HIV2. The population that was submitted to blood tests (75%) was compared to the one that missed the test and it was found that no important differences were present between the two. The criteria for HIV1 or HIV2 positive results were the presence of a positive ELISA test confirmed by an Western Blot revealing antibodies against the three proteins env, core and gag. For a test to be considered positive results by both methods had to be found in a second sample collected later. The prevalences of infection were of 0.29% for HIV1 and 0.29% for HIV2 although the prevalence of HIV2 in the population of African origin was higher (1.45%). The six seropositive cases detected included a drug addict, one prostitute, one case of African origin and two cases with multiple sexual partners. The clinical, epidemiological and immunological features of the seropositive cases are presented and the prevalence found is discussed in the context of other portuguese data.(ABSTRACT TRUNCATED AT 250 WORDS)