SARS-CoV-2 in saliva, oropharyngeal and nasopharyngeal specimens.

INTRODUCTION: The reference test to evaluate patients with suspected respiratory virus infection is a real-time reverse transcription-polymerase chain reaction (RT-PCR) from a nasopharyngeal swab (NPS). However, other specimen collection methods such as an oropharyngeal swab (OPS) or saliva specimen are also used for SARS-CoV-2 testing during the ongoing COVID-19 pandemic. However, it remains unclear if rates of SARS-CoV-2 detection differ between sampling methods. This study will compare the rates of SARS-CoV-2 detection by saliva, OPS, and NPS sampling in a public setting. METHODS: Individuals referred for outpatient SARS-CoV-2 testing will be invited to participate in a prospective clinical study. They will have saliva, OPS and NPS specimens collected that will be analysed separately for SARS-CoV-2 RNA by RT-PCR. The rate of SARS-CoV-2 detection in saliva, OPS and NPS will be compared using a logistic regression mixed-effect model analysis. A sample of 19,110 participants is required at an expected 1.5% test-positive rate in order to detect a 25.6% difference. The total sample size will be adjusted as the test-positive rate changes. CONCLUSIONS: This study will provide evidence for the optimal site of specimen collection to detect SARS-CoV-2. The results may help guide the health authorities. FUNDING: This is an investigator-initiated trial based on an unrestricted grant from the Novo Nordisk Foundation and the Aage og Johanne Louis-Hansens Fond. The foundations have had no say in the decisions on study design or reporting. TRIAL REGISTRATION: ClinicalTrials.gov (ID: NCT04715607).

Anti-Lipoarabinomannan-Specific Salivary IgA as Prognostic Marker for Leprosy Reactions in Patients and Cellular Immunity in Contacts.

Leprosy causes the most common peripheral neuropathy of infectious etiology, posing an important public health problem worldwide. Understanding the molecular and immunological mechanisms of nerve damage induced by M. leprae is mandatory to develop tools for early diagnosis and preventive measures. The phenolic glycolipid 1 (PGL-1) and lipoarabinomannan (LAM) antigens are major components of the bacterial surface and are implicated on leprosy immunopathogenesis and neural damage. Although the anti-PGL-1 serum IgM is highly used for operational classification of patients, the anti-LAM salivary IgA (sIgA) has not been investigated as diagnostic or prognostic marker in leprosy. Our aim was to assess the presence of anti-LAM sIgA in leprosy patients and their contacts in order to demonstrate whether such expression was associated with leprosy reactions. Distinct patterns of anti-LAM slgA were observed among groups, which were stratified into treatment-naïve patients (116), patients who completed multidrug therapy-MDT (39), household contacts (111), and endemic controls (11). Both anti-LAM sIgA and anti-PGL-I serum IgM presented similar prognostic odds toward leprosy reactions [(odds ratio) OR = 2.33 and 2.78, respectively]. Furthermore, the anti-LAM sIgA was highly correlated with multibacillary (MB) forms (OR = 4.15). Contrarily, among contacts the positive anti-LAM sIgA was highly correlated with those with positive Mitsuda test, suggesting that the presence of anti-LAM slgA may act as an indicator of cellular immunity conferred to contacts. Our data suggest that anti-LAM slgA may be used as a tool to monitor patients undergoing treatment to predict reactional episodes and may also be used in contacts to evaluate their cellular immunity without the need of Mitsuda tests.

Salivary anti-PGL-1 IgM may indicate active transmission of Mycobacterium leprae among young people under 16 years of age

Abstract Considering that the main route of Mycobacterium leprae transmission is the upper respiratory tract, detection of salivary antibodies can be a useful tool for diagnosing early infection. The study aimed to analyze salivary anti-PGL-1 IgA and IgM antibodies in 169 children aged 4-16 years old, who lived nearby or inside the house of multibacillary or paucibacillary leprosy patients in two endemic cities in Alagoas State - Brazil. Salivary anti-PGL-1 antibodies were quantified by modified ELISA method. The frequency of contact and clinical form of the index case were significantly associated with salivary antibody levels. High frequency of IgM positivity strongly suggests active transmission of M. leprae in these communities. We suggest in the present work that salivary anti-PGL IgA and IgM are important biomarkers to be used for identifying communities with probable active transmission of M. leprae.

Salivary anti-PGL-1 IgM may indicate active transmission of Mycobacterium leprae among young people under 16 years of age.

Considering that the main route of Mycobacterium leprae transmission is the upper respiratory tract, detection of salivary antibodies can be a useful tool for diagnosing early infection. The study aimed to analyze salivary anti-PGL-1 IgA and IgM antibodies in 169 children aged 4-16 years old, who lived nearby or inside the house of multibacillary or paucibacillary leprosy patients in two endemic cities in Alagoas State - Brazil. Salivary anti-PGL-1 antibodies were quantified by modified ELISA method. The frequency of contact and clinical form of the index case were significantly associated with salivary antibody levels. High frequency of IgM positivity strongly suggests active transmission of M. leprae in these communities. We suggest in the present work that salivary anti-PGL IgA and IgM are important biomarkers to be used for identifying communities with probable active transmission of M. leprae.

The oral cavity in leprosy: what clinicians need to know.

Leprosy is a chronic infectious disease caused by Mycobacterium leprae, a bacillus that has a tropism for skin and peripheral nerves. Leprosy treatment is based on a multidrug therapy established by the World Health Organization in 1982 and, despite its widespread use, Brazil ranks second worldwide in numbers of cases. Oral involvement in leprosy has been poorly described in the literature, and few studies have shown that although the bacillus is found in mucosa, specific leprosy lesions are rare and affect patients with advanced stages of the disease. This review aimed to assess the literature on oral manifestations in leprosy and the aspects involving oral cavity in leprosy pathogenesis.

Saliva as a Diagnostic Tool for Measurement of Total Antioxidant Capacity in Children with Leprosy and Born to Leprosy Parent.

The aim of the study is to assess the role of saliva as a diagnostic tool for measurement of total antioxidant capacity in children with leprosy and children born to leprosy parent. One hundred fifty children in the age group of 4-15 years were split into three equal groups: children with leprosy (CL) and children born to leprotic parents (CLP) and healthy children. Vitamin C level was measured in saliva of children spectrophotometrically at 695nm by Phosphomolybdenum method. Data were determined with student's unpaired t test and one way ANOVA. The result of the study showed that children with leprosy exhibited significantly decreased salivary total antioxidant capacity as compared to healthy controls. Antioxidant Vitamin C was higher in the Paucibacillary leprosy (PB) than those of Multibacillary type (MB) (P < 0.001). As age advanced, there was a gradual increase in total antioxidant capacity in both the control and study groups and the results were highly significant statistically. Saliva is an easy medium.

Detection of Mycobacterium leprae in saliva and the evaluation of oral sensitivity in patients with leprosy.

The aim of this study was to investigate sensitivity disorders in the oral cavity related to the presence of Mycobacterium leprae in the saliva of treatment-naïve patients with leprosy in the state of Amazonas, Brazil. A cross-sectional study was conducted involving 45 subjects with leprosy. The subjects were interviewed to evaluate the sensitivity of the oral cavity. For the detection of M. leprae, saliva and slit-skin smear samples were collected. The samples were analysed using a bacteriological index (BI) protocol and the real-time quantitative polymerase chain reaction (qPCR). The results indicated that 15 of the 45 (33.3%) subjects with leprosy showed decreased oral sensitivity, which confirmed the importance of the oral cavity sensitivity evaluation. There was not a direct relationship between the presence of M. leprae in saliva and changes in oral sensitivity. Positive saliva qPCR results from six (31.6%) of 19 paucibacillary (PB) patients suggested the possibility of a new site for sample collection. Positive results using these diagnostic techniques (BI, slit-skin smear and saliva qPCR) increased to 55.5%, thus opening the possibility of combining these different techniques to increase the rate of positive diagnoses, especially in PB patients.

Detection of Mycobacterium leprae in saliva and the evaluation of oral sensitivity in patients with leprosy

The aim of this study was to investigate sensitivity disorders in the oral cavity related to the presence of Mycobacterium leprae in the saliva of treatment-naïve patients with leprosy in the state of Amazonas, Brazil. A cross-sectional study was conducted involving 45 subjects with leprosy. The subjects were interviewed to evaluate the sensitivity of the oral cavity. For the detection of M. leprae, saliva and slit-skin smear samples were collected. The samples were analysed using a bacteriological index (BI) protocol and the real-time quantitative polymerase chain reaction (qPCR). The results indicated that 15 of the 45 (33.3%) subjects with leprosy showed decreased oral sensitivity, which confirmed the importance of the oral cavity sensitivity evaluation. There was not a direct relationship between the presence of M. leprae in saliva and changes in oral sensitivity. Positive saliva qPCR results from six (31.6%) of 19 paucibacillary (PB) patients suggested the possibility of a new site for sample collection. Positive results using these diagnostic techniques (BI, slit-skin smear and saliva qPCR) increased to 55.5%, thus opening the possibility of combining these different techniques to increase the rate of positive diagnoses, especially in PB patients.

Anti-PGL1 salivary IgA/IgM, serum IgG/IgM, and nasal Mycobacterium leprae DNA in individuals with household contact with leprosy.

OBJECTIVES: Leprosy household contacts represent a group at high risk of developing the disease. The aim of this study was to detect Mycobacterium leprae subclinical infection in this group through serological and molecular parameters. METHODS: Serum anti-PGL1 IgG/IgM and salivary anti-PGL1 IgA/IgM was investigated using an ELISA, and nasal carriage of M. leprae DNA was detected by PCR, in leprosy household contacts of paucibacillary (PB) and multibacillary (MB) household leprosy patients (n=135), their index cases (n=30), and in persons living in a low endemic city (n=17). RESULTS: Salivary anti-PGL1 IgA and IgM and serum anti-PGL1 IgG showed good correlation comparing contacts and index cases (p<0.01, p<0.005, and p<0.0001, respectively). This was not observed for serum anti-PGL1 IgM (p>0.05). A high frequency of anti-PGL1 IgM positivity was found in IgG-negative samples (p<0.0001). For IgG-positive samples, IgM antibodies were also positive in most of the samples. None of the 17 volunteers living in a low endemic city presented seropositivity for IgG; however, two of them showed positivity for anti-PGL1 IgM. M. leprae DNA was found in the nasal swabs of nine out of the 85 MB household leprosy contacts (10.6%) and in three out of the 50 PB household leprosy contacts (6.0%). CONCLUSION: We strongly suggest that serum IgG/IgM and salivary anti-PGL1 IgA/IgM measurements are used to follow leprosy household contacts.

Seasonal and regional dynamics of M. ulcerans transmission in environmental context: deciphering the role of water bugs as hosts and vectors.

BACKGROUND: Buruli ulcer, the third mycobacterial disease after tuberculosis and leprosy, is caused by the environmental mycobacterium M. ulcerans. Various modes of transmission have been suspected for this disease, with no general consensus acceptance for any of them up to now. Since laboratory models demonstrated the ability of water bugs to transmit M. ulcerans, a particular attention is focused on the transmission of the bacilli by water bugs as hosts and vectors. However, it is only through detailed knowledge of the biodiversity and ecology of water bugs that the importance of this mode of transmission can be fully assessed. It is the objective of the work here to decipher the role of water bugs in M. ulcerans ecology and transmission, based on large-scale field studies. METHODOLOGY/PRINCIPAL FINDINGS: The distribution of M. ulcerans-hosting water bugs was monitored on previously unprecedented time and space scales: a total of 7,407 water bugs, belonging to large number of different families, were collected over one year, in Buruli ulcer endemic and non endemic areas in central Cameroon. This study demonstrated the presence of M. ulcerans in insect saliva. In addition, the field results provided a full picture of the ecology of transmission in terms of biodiversity and detailed specification of seasonal and regional dynamics, with large temporal heterogeneity in the insect tissue colonization rate and detection of M. ulcerans only in water bug tissues collected in Buruli ulcer endemic areas. CONCLUSION/SIGNIFICANCE: The large-scale detection of bacilli in saliva of biting water bugs gives enhanced weight to their role in M. ulcerans transmission. On practical grounds, beyond the ecological interest, the results concerning seasonal and regional dynamics can provide an efficient tool in the hands of sanitary authorities to monitor environmental risks associated with Buruli ulcer.

Mycobacterium leprae in the periodontium, saliva and skin smears of leprosy patients / Mycobacterium leprae no periodonto, saliva e raspados intradérmicos de sujeitos com hanseníase

Purpose: To verify the presence of M. leprae in the periodontium, saliva and skin slit smears of leprosy patients. To correlate bacteriological and molecular findings with clinical data and compare laboratory techniques. Methods: A cross-sectional study was designed to use bacteriological (baciloscopy) and molecular (PCR) parameters to detect M. leprae in exudates of the gingival sulcus/periodontium pocket, saliva and skin slit smears from multiple clinical forms of leprosy patients without previous treatment. Results: The study included 48 leprosy patients with 15 multibacillary (MB) cases and 33 paucibacillary (PB) cases. The diagnosis of MB was confirmed through bacteriological examination and PCR results from skin slit smears. A total of 16 (48.5%) PB patients were PCR positive only. Four PB patients with negative PCR skin smears were PCR positive for the periodontium and saliva, with 2 cases and 1 case, respectively. No periodontium or saliva samples had positive bacteriological results. Conclusion: There was no correlation between periodontal disease and the presence of M. leprae. Bacteriological examination did not prove to be an efficient technique for the analysis of saliva and periodontium samples. PCR analysis of skin smears was more efficient at diagnosing PB patients than bacteriological examination. PCR positive results for the detection of M. leprae in PB patients can be increased by collecting slit skin smears, periodontium and saliva samples.

Objetivo: verificar através da baciloscopia e da reação em cadeia da polimerase (PCR) a presença do M. leprae no periodonto, saliva e raspados intradérmicos de pacientes com hanseníase. Metodologia: Realizou-se um estudo transversal do tipo detecção de casos numa instituição referência de hanseníase no Amazonas. Resultados: Foram avaliados 48 pacientes, sendo 15 multibacilares (MB) e 33 paucibacilares (PB). Os pacientes MB tiveram o diagnóstico confirmado pela baciloscopia e PCR dos raspados intradérmicos, enquanto que 16 (48,5%) dos PB foram positivos apenas na PCR. Quatro pacientes PB negativos na PCR de raspados intradérmicos foram positivos no periodonto e na saliva, 1 positivo na saliva e 2 no periodonto. Nenhuma amostra do periodonto e da saliva foi positiva na baciloscopia. Conclusão: Não houve relação entre a doença periodontal e a presença do M. leprae; a baciloscopia não mostrou ser uma técnica eficiente para análise da saliva e periodonto; a técnica de PCR de raspado dérmico mostrou ser um método mais eficaz no diagnóstico dos PB do que a baciloscopia; a positividade da PCR para detecção do M. leprae nos PB pode ser aumentada coletando raspado intradérmico, periodonto e saliva.

Study of cross-reactivity of Mycobacterium leprae reactive salivary IgA with other environmental mycobacteria.

Majority of the endemic population is exposed to Mycobacterium leprae but very few develop disease. Humoral mucosal immune response mediated through M. leprae reactive salivary antibodies has been suggested to be quite important in the protective immunity. As the endemic population is also exposed to many environmental mycobacteria, we tested saliva from 121 subjects for the cross-reactivity of the M. leprae reactive salivary antibodies to mycobacteria like M. smegmatis and M. phlei. Saliva samples were treated with these two mycobacteria prior to testing M. leprae reactive antibodies by ELISA. In 59 subjects (48.76%), original and cross-reacted saliva showed same absorbance values suggesting no cross-reactivity. 26 subjects (21.49%) showed less than 25% drop in the OD values whereas 21 subjects (17.4%) showed 25% to 50% drop after reacting saliva with the mycobacteria. 15 subjects (12.4%) showed more that 50% drop in OD. The data suggest that though in half of subjects antibodies did not cross-react with mycobacteria tested, there were subjects where antibodies showed cross-reactivity to mycobacteria suggesting that positive salivary M. leprae reactive IgA response could be to some extent due to exposure to environmental mycobacteria and it could also be protective against M. leprae.

Salivary anti-PGL IgM and IgA titers and serum antibody IgG titers and avidities in leprosy patients and their correlation with time of infection and antigen exposure.

The present work proposed to correlate serum antibody avidity and salivary antibody titers as parameters for time of infection and antigen exposure in a cohort study evaluating leprosy patients in different periods of treatment. Colorimetric enzyme-immunoassays for salivary antibodies, serum antibody IgG titers and avidities were performed in the samples. Anti-PGL-1 IgA and IgM salivary antibodies were significantly higher in multibacillar (MB-L) patients compared to normal controls (p<0.05), but not when compared to borderline tuberculoid (BT) or to paucibacillar (PB-L) patients (p>0.05). A good correlation was found between salivary anti-PGL-1 IgA and IgM levels in MB-L patients (r=0.41, p<0.01). Two out of 33 tested saliva samples from patients who had completed the drug regimen treatment presented positive salivary antibodies. Among non-treated patients, samples with low, medium or high serum IgG antibody avidity were found in similar frequencies. In patients under treatment, most of the serum samples showed low or medium IgG antibody avidity. The treated MB-L patients showed medium or high antibody avidity, except for two, who showed very low antibody avidity results. We suggest that salivary anti-PGL antibodies and serum IgG avidity could be useful for the indication of recent exposure or re-exposure to bacteria after chemotherapy.

Salivary anti-PGL IgM and IgA titers and serum antibody IgG titers and avidities in leprosy patients and their correlation with time of infection and antigen exposure

The present work proposed to correlate serum antibody avidity and salivary antibody titers as parameters for time of infection and antigen exposure in a co-hort study evaluating leprosy patients in different periods of treatment. Colorimetric enzyme-immunoassays for salivary antibodies, serum antibody IgG titers and avidities were performed in the samples. Anti-PGL-1 IgA and IgM salivary antibodies were significantly higher in multibacillar (MB-L) patients compared to normal controls (p<0.05), but not when compared to borderline tuberculoid (BT) or to paucibacillar (PB-L) patients (p>0.05). A good correlation was found between salivary anti-PGL-1 IgA and IgM levels in MB-L patients (r=0.41, p<0.01). Two out of 33 tested saliva samples from patients who had completed the drug regimen treatment presented positive salivary antibodies. Among non-treated patients, samples with low, medium or high serum IgG antibody avidity were found in similar frequencies. In patients under treatment, most of the serum samples showed low or medium IgG antibody avidity. The treated MB-L patients showed medium or high antibody avidity, except for two, who showed very low antibody avidity results. We suggest that salivary anti-PGL antibodies and serum IgG avidity could be useful for the indication of recent exposure or re-exposure to bacteria after chemotherapy.

Early trafficking events of Mycobacterium ulcerans within Naucoris cimicoides.

The severe skin-destructive disease caused by Mycobacterium ulcerans, named Buruli ulcer, is the third most important mycobacterial disease in humans after tuberculosis and leprosy. Recently we demonstrated that M. ulcerans could colonize the salivary glands of the water bug, Naucoris cimicoides. In this study, we report that M. ulcerans may be delivered from the digested prey aspirate to the coelomic cavity via a unique headspace, the head capsule (HC). During the infected meal, we observed that M. ulcerans clusters adhered to the stylets that were retracted in the HC at the end of the meal. M. ulcerans was able to translocate from the HC to the coelomic cavity where it is phagocytosed by the plasmatocytes. These cells are subverted as shuttle cells and deliver M. ulcerans to the salivary glands. At this early stage of its parasitic life style, two other important features of M. ulcerans can be documented: first, mycolactone is not required for translocation of M. ulcerans into the HC, in contrast to the next step, colonization of the salivary glands; second, M. ulcerans clusters bind a member of the serpin protein family present in the salivary gland homogenate.

[Detection of antibodies to M. leprae in saliva of lepric patients].

Saliva of 116 lepric patients were scanned for antibodies in ELISA (with M. leprae cultivated in vitro used as antigen) in order to work out an invasion-free diagnostic tool for lepra. The ELISA findings for "saliva-serum" pairs from same patients showed an increased level of antibodies both in serum and saliva in 39.7% of cases, and matching of results (positive and negative ones) was observed in 73.3% of patients. The increasing level of specific antibodies as observed in intensification of the lepric process in blood serum occurred simultaneously with its increase in saliva. The invasion-free diagnostics of lepra is promising for examinations of contact persons and of population in endemic regions as well as for evaluating the efficiency of the antilepric therapy.

An approach to understanding the transmission of Mycobacterium leprae using molecular and immunological methods: results from the MILEP2 study.

BACKGROUND: The current strategy for leprosy control using case detection and treatment has greatly reduced the prevalence of leprosy, but has had no demonstrable effect on interrupting transmission. METHODS: Three leprosy endemic communities in India were recruited, examined, and followed up sequentially over 2 yrs using nasal swabs and saliva collections. The nasal swabs were tested by polymerase chain reaction for the presence of M. leprae and the saliva was assayed for anti-M. leprae IgA. FINDINGS: Only 1.6% of 2552 nasal swabs were PCR positive, and 68% of saliva samples were positive for ML-IgA. BCG and household contact status was associated with the mucosal immune response, but not with PCR positivity. PCR positivity did not persist and most PCR positive results were in the wet season. INTERPRETATION: The findings contribute to our understanding of the epidemiology of M. leprae and the possible periods of greatest likelihood of exposure and transmission.

Pesquisa de antígenos ABH em eritrócitos e na saliva de pacientes hansenianos / ABH antigens research in erythrocytes and at leprosy patients saliva

Os poucos estudos já publicados sobre a determinaçäo de fenótipo secretor dos antígenos ABH na saliva de hansenianos têm demonstrado näo haver uma correlaçäo significativa entre estas substâncias e a suscetibilidade à doença. No presente estudo avaliamos 74 pacientes, sendo 27 virchovianos, 23 tuberculóides e 24 dimorfos, quanto à presença de antíngenos ABH nos eritrócitos e na saliva, pela reaçäo de aglutinaçäo em tubo e inibiçäo de aglutinaçäo. A frequência dos grupos sanguineos ABO e do fenótipo secretor e näo secretor nestes pacientes e no grupo controle foram: O= 40,5(por cento) 49(por cento); AB= 6,8(por cento) 3,6(por cento) e näo secretor= 31,1(por cento) 17,5(por cento). Analisando-se os resultados apresentados nos hansenianos, observamos que näo houve antígenos ABH pesquisados nos eritrócitos e na saliva

Transmission and protection in leprosy: indications of the role of mucosal immunity.

Recent advances in treatment have achieved a large drop in the prevalence of active leprosy cases, but the incidence is at best decreasing slowly. Most people within leprosy-endemic populations have been exposed to Mycobacterium leprae, but few develop disease and it seems likely that the majority of the population develops protective immunity. If the site of initial infection is in the nose, dissemination of bacilli around the body to skin and nerve implies that the initial infection is bacilliferous and it has been shown that nasal M. leprae are detectable by polymerase chain reaction (PCR) of nasal swabs. Since salivary anti-M. leprae IgA (sMLIgA) levels are correlated with protection, we have surveyed groups of leprosy patients, contacts and the general population for both their sMLIgA and nasal PCR positivity. A total of 304 subjects were enrolled in the study: PCR and mucosal challenge tests were performed in 204 of these individuals. sMLIgA was present in 66% of treated patients, 76% of leprosy workers and 72% of healthy contacts. However, only 33% of indigenous subjects were sMLIgA+, in contrast to the earlier studies showing 74% positivity. PCR for M. leprae was present in both household contacts (2%) and indigenous controls (5%). In a subsequent follow-up study, nasal swabs were taken from 97 of those studied in the first series: three PCR+ individuals followed up after one year became negative, while of the remaining 94 PCR- individuals retested, 2 became positive. Of 112 subjects retested with the mucosal challenge test for sMLIgA: 22 converted from positive to negative and 12 from negative to positive. These results suggest that there is widespread subclinical transmission of M. leprae with transient infection of the nose resulting in the development of a mucosal immune response, despite the fact that few individuals will develop clinical disease. This may explain the current lack of effect of multidrug therapy (MDT) control programmes on incidence, although the reduction in general population immunity is consistent with some effect of MDT on transmission.

Development of a mucosal challenge test for leprosy using leprosin A.

There is little information about the mucosal immune response in leprosy. We have developed a nasal provocation test with leprosin A which will be used to investigate mucosal immunity to Mycobacterium leprae. Initial studies were performed with increasing doses of leprosin A (1.0 pg/ml-10 micrograms/ml) to determine the optimal safe dose of leprosin A. Anti-M. leprae IgA antibody and normal IgA concentrations were measured in the saliva of leprosy contacts and controls before and after instillation of leprosin A. Nasal leprosin A was well tolerated up to a concentration of 10 micrograms/ml without side effects. None of the six subjects who had not been exposed to leprosy had salivary IgA against whole M. leprae, whereas IgA was detected from 64 h to 140 h following instillation of leprosin A in all of the leprosy hospital workers and in 15 out of 18 healthy household contacts tested. There was no correlation between serum and salivary anti-M. leprae IgA levels before and after testing. Salivary IgA anti-lipoarabinomannan responses were seen in 12 out of 20 household contacts. Normal salivary IgA concentrations varied from 8 to 240 mg/l. The leprosin A nasal provocation test appears to be a safe method for the investigation of the role of mucosal immunity in the pathogenesis of leprosy.