Paratuberculosis (PTB) is a chronic enteritis determined by Mycobacterium avium subsp. paratuberc... more Paratuberculosis (PTB) is a chronic enteritis determined by Mycobacterium avium subsp. paratuberculosis (Map) that affects ruminants. Three crossbred dairy cattle with clinical PTB were necropsied; tissue samples were collected and processed for histopathology and culture. Intestinal lesions were characterized in three levels of severity (mild, moderate and severe) by gross examination. Gross examination, microscopy and tissue culture were analyzed and compared. Mean tissue culture sensitivity was 66.6%. Map was recovered from 42.8% of intestinal mild lesions, 55.5% of intestinal moderate lesions, and 100% of severe intestine lesions. The results indicate a significant correlation between the level of lesions severity and the isolation of Map. KEY WORDS : Cattle, Johne’s disease, Map, paratuberculosis, pathology
Swine are susceptible to different mycobacteria species, being Mycobacterium bovis an agent of tu... more Swine are susceptible to different mycobacteria species, being Mycobacterium bovis an agent of tuberculosis, with most significant zoonotic risks, while M. avium determines a granulomatous lymphadenitis with low zoonotic risk. Currently performed intradermal tests present some important limitations, such as the lack of ability to detect anergic animals or to differentiate among mycobacterial species. In order to improve the TB diagnosis, serological assays have been developed, with encouraging results. The purpose of this study was to evaluate the performance of a MPB70-ELISA in 82 piglets divided into four groups: sensitized by inactivated M. bovis, M. avium, inoculated with oil adjuvant, or with saline solution. The test was able to discriminate between an animal sensitized by M. bovis and animals of the three other groups, including M. avium-sensitized animals; for this reason, we suggest that MPB70-ELISA could be used as a complementary tool for discriminating the agent of the m...
Microsporidia are emerging as opportunistic pathogens in patients with acquired immunodeficiency ... more Microsporidia are emerging as opportunistic pathogens in patients with acquired immunodeficiency syndrome (AIDS). Enterocytozoon bieneusi is the most commonly reported microsporidium that is detected in gastrointestinal specimens. This report describes an in situ hybridization technique with a 30-base specific synthetic DNA probe for detection of E bieneusi by light microscopy. Formalin-fixed paraffin-embedded duodenal biopsy specimens from three patients with AIDS, chronic diarrhea, and E bieneusi infection confirmed by electron microscopy were used in this study. Light microscopic examination after colorimetric detection allowed the identification of different stages of the pathogen's life cycle in the cytoplasm of enterocytes. No cross-reactivity was noted between the probe and human DNA. Our study underscores the applicability of a synthetic-labeled oligonucleotide for the detection and identification of E bieneusi in clinical samples.
The interference of bovine tuberculosis (TB) on the efficacy of paratuberculosis (PTB) diagnostic... more The interference of bovine tuberculosis (TB) on the efficacy of paratuberculosis (PTB) diagnostic tests has been evaluated. A group of 32 tuberculous cows identified by both intradermal tests and gamma-interferon assay, 16 of them confirmed by the recovery of M.bovis from tissues, was tested by three different PTB-ELISAs, being two commercials and one in-house. The rest of the adult animals of the herds, totalizing 216 TB-negative animals, were also tested as a control group. Fecal culture for PTB was negative in all animals, but seven (21.8%) tuberculous cows produced false-positive reactions when tested by various PTB-ELISAs, leading to a misdiagnosis. Tuberculosis impairs the specificity of serological tests for paratuberculosis diagnosis and should be considered for the reliability of PTB control programs.
Paratuberculosis (PTB) in Brazil has previously only been reported in imported animals and is off... more Paratuberculosis (PTB) in Brazil has previously only been reported in imported animals and is officially considered as an exotic disease. A dairy herd, which had no imported animals, presented clinically suspect animals and was investigated for paratuberculosis using faecal culture, histopathology, indirect ELISA and the agar gel immunodiffusion test. Infection with Mycobacterium avium subsp. paratuberculosis (Map) was confirmed by culture of faeces from five cows with clinical symptoms of PTB and in 7/24 randomly selected asymptomatic cows from the same herd. Two cows with clinical symptoms were necropsied and their tissues were positive for Map by culture and histopathology. Twelve asymptomatic, randomly selected cows were positive on ELISA. The results confirmed the presence of PTB in this dairy herd and for the first time demonstrated the disease in a herd of native-bred cattle in Brazil.
Bovine tuberculosis is a worldwide disease. In spite of its wide use, intradermal tuberculin reac... more Bovine tuberculosis is a worldwide disease. In spite of its wide use, intradermal tuberculin reactions present some important limitations, related to their sensitivity and specificity. The use of serological tests such as ELISA has been suggested as an alternative test for tuberculosis field diagnosis. Skin-test reactive animals are obligatorily slaughtered and, in many cases, lesions characteristic for tuberculosis are not found. In those cases, the reliability of the test may be questioned and confirmatory tests may be required. In the absence of lesions culture or histopathology becomes very difficult to perform, and ELISA might represent an alternative choice for confirmatory diagnosis. We collected blood samples from 97 skin-test reactive adult cows at slaughter. Samples were centrifuged and sera tested by ELISA-PPD using an in-house protocol previously standardized by our group (Lilenbaum et al., 1999). When lesions were found, tissue samples were collected for histopathology and M. bovis culture. Seventy animals presented lesions and histopathology confirmed the diagnosis in 63 of them, while only 35 grew M. bovis. Thirty-three animals were positive by ELISA, indicating a low sensitivity of the test, of 34.1%, and a poor agreement with skin-test (kappa index = 0.125). Although several authors reported sensitivity for ELISA in field trials as high as 90% (Ritacco et al., 1987), the rate observed in the present study was very disappointing. Therefore, due to its low sensitivity we believe ELISA should not be considered as a reliable confirmatory test for bovine tuberculosis diagnosis at the slaughter.
A herd infected naturally with tuberculosis was investigated by different diagnostic methods. Nin... more A herd infected naturally with tuberculosis was investigated by different diagnostic methods. Ninety days after a screening test that identified 21 cows as skin test positive, a Comparative Intradermal Tuberculin Test (CITT) was performed in those 21 cows and in 29 other randomly selected skin test negative cows. Milk samples and nasal swabs were collected prior to the CITT for bacteriological culture and PCR, while blood samples were collected for IFN release and antibody responses to MPB70 and MPB83, at three time points post tuberculin injection. Animals positive by CITT were slaughtered and disease confirmation undertaken. Based on the Kappa test, IFN was comparable to the standard tests (culture, PCR and CITT) at all three sampling points. Results from both antibody ELISAs were similar but were not comparable to the standard tests. T-test analysis of the CITT, IFN and ELISAs demonstrated that their performances were not correlated. There is increasing recognition that individua...
The diagnosis of bovine tuberculosis aims to identify the immune response against mycobacterial a... more The diagnosis of bovine tuberculosis aims to identify the immune response against mycobacterial antigens. Although Single Intradermal Comparative Cervical Tuberculin test (SICCT) is broadly used for first identification of the disease, the performance of ELISAs has been investigated for diagnosis improvement. The present study expected to find out the influence of intradermal skin tests on the results of ELISAs using the recombinant proteins MPB70 and MPB83 as antigens on cows from a naturally infected herd. Results were analyzed by the F-test, Mann-Whitney and Friedman tests Although comparable to both proteins, results showed that positive animals presented a tendency of augment reactivity to MPB70, representing a tendency for a booster effect, but not to MPB83.
This investigation aimed at the detection of Mycobacterium tuberculosis (MTB) in the sputum of Su... more This investigation aimed at the detection of Mycobacterium tuberculosis (MTB) in the sputum of Suruí Indian subjects from Amazonia, Brazil. Polymerase chain reaction analyses were positive for12 samples, five of which were also culture-positive (N = 147). Four MTB genotypes were identified, one of which showed resistance to rifampicin and isoniazid. The study also highlighted one village complex as of particular importance, considering the relatively high number of tuberculosis cases reported and of MTB isolates obtained.
We evaluated, for the first time in Latin America, the performance of a commercial enzyme immunoa... more We evaluated, for the first time in Latin America, the performance of a commercial enzyme immunoassay (EIA) (Calypte Biomedical Corporation, Berkeley, Calif.) that detects human immunodeficiency virus type 1 (HIV-1)-specific antibodies in urine in comparison to standard serological assays (two commercial EIAs and a commercial Western blot [WB] assay). Paired serum and urine specimens were collected from two different groups of Brazilian patients: 225 drug users with unknown HIV status who attended drug treatment centers in Rio de Janeiro, Brazil, and 135 subjects with known HIV status. Patients showing positive results in the serum EIAs and/or in the urine EIA were serologically confirmed by WB assay. For 135 individuals with known HIV status, the urine EIA showed 100% sensitivity (74 positive samples) and 95.1% specificity (58 of 61 negative specimens). For 225 drug users, the test showed 100% sensitivity (2 positive samples) and 98.7% specificity (220 of 223 negative samples) comp...
Comparative Immunology, Microbiology and Infectious Diseases, 2010
In order to demonstrate the potential to distinguish paratuberculosis (PTB) from bovine tuberculo... more In order to demonstrate the potential to distinguish paratuberculosis (PTB) from bovine tuberculosis infection (TB), ELISAs with M. bovis-specific MPB70 or MPB83 as capture antigens were developed and tested on two groups of cattle: Group A comprised 23 animals positive for Mycobacterium avium paratuberculosis (Map) and TB free. Group B comprised 48 animals from a Map free herd during the previous 5 years, but confirmed as tuberculous by positive results on PPD testing and M. bovis culture. Results demonstrated a significant difference (p < 0.01) between reactivity of sera from these groups, encouraging the study of purified proteins to differentiate between both diseases.
An in-house PPA-ELISA was compared to a commercial ELISA using a panel of 108 serum samples. In r... more An in-house PPA-ELISA was compared to a commercial ELISA using a panel of 108 serum samples. In relation to commercial test, in-house assay presented 100% of sensitivity and 83.5% of specificity and a high concordance (κ> 0.5), which demonstrates that the in-house assay is a valuable tool for use in developing countries.
Forty-four cows from five herds infected with tuberculosis (TB) and without paratuberculosis (PTB... more Forty-four cows from five herds infected with tuberculosis (TB) and without paratuberculosis (PTB), and 21 cows from a herd without either infection were studied. The cattle presented concordant results in both the skin test and γ-interferon assay for TB and two commercial ELISAs for PTB. Animals were divided according to TB test results into Group A with 28 TB-infected animals, Group B with 16 TB-negative animals from infected herds, and Group C with 21 TB-negative cows from a tuberculosis-free herd (which were used as controls). Twenty of 28 animals from Group A (71.4%), 6/16 from Group B (37.5%) and none from Group C were reactive to PTB ELISAs, suggesting that these commercial kits were unable to distinguish between PTB and TB. It is proposed that natural occurring TB strongly interferes in the diagnosis of PTB and that commercial ELISAs cannot be considered reliable tools in the diagnosis of paratuberculosis in tuberculosis-infected herds.
Paratuberculosis is a chronic enteritis that affects ruminants and is caused by Mycobacterium avi... more Paratuberculosis is a chronic enteritis that affects ruminants and is caused by Mycobacterium avium paratuberculosis (Map). The disease is worldwide spread and causes important economic losses. In Brazil, the bacillus was isolated in the south and northeast regions of the country and in Rio de Janeiro, but there are no enough epidemiological studies about its occurrence. Isolation of Map from tissues or fecal samples is 100% specific, but Map shows the most fastidious growth of all mycobacteria. Incubation lasts 8-12 weeks, with a dependency on exogenous mycobactin J. Diagnostic tests based on specific DNA sequences allow fast and secure identification, and PCR has been used to confirm positive culture results and to identify Map in feces, milk and tissues. The most frequently used target sequences are the gene encoding the 16S rRNA, and the insertion element IS900. Serological assays are widely used for the herd diagnosis of the disease. A commercial ELISA with M. phlei pre-adsorption step achieves a specificity of 95.4% to 99% and a sensitivity of about 45%. Until now, there is no effective treatment for ill animals and control programs are based on managing procedures of herds and culling of symptomatic animals. In Brazil, paratuberculosis was recently identified and has been demonstrated even in autochthonous closed herds. Therefore, it is essential to perform an epidemiological national research and to investigate the economic impact of the disease in our herds. These results could promote a control program of paratuberculosis adapted to the Brazilian requirements.
ELISAs for paratuberculosis employ a preadsorption step with Mycobacterium phlei to diminish unsp... more ELISAs for paratuberculosis employ a preadsorption step with Mycobacterium phlei to diminish unspecific reactions As M. fortuitum is one of the most frequent environmental mycobacteria, the purpose of this pilot study was to evaluate its use as an alternative for the preadsorption in ELISAs for paratuberculosis. Results suggest that M. fortuitum can be an alternative instead of or associated to M. phlei with comparable results (κ > 0.8) to conventional ELISAs using M. phlei as a preadsorption antigen.
We evaluated the performance of the AMPLICOR MTB assay for detection of M. tuberculosis in clinic... more We evaluated the performance of the AMPLICOR MTB assay for detection of M. tuberculosis in clinical specimens obtained from 98 smear-negative tuberculous patients (43 with positive and 55 with negative culture results). The sensitivity of the AMPLICOR MTB was 44.9% (44/98) and that of culture was 43.8% (43/ 98). No significant difference was observed between the results obtained by AMPLICOR MTB and by culture. We conclude that amplification assays could be used for testing smear-negative specimens because a rapid diagnosis will benefit those patients.
Background Tuberculosis (TB) remains a major world health problem. Around 2 billions of people ar... more Background Tuberculosis (TB) remains a major world health problem. Around 2 billions of people are infected by Mycobacterium tuberculosis, the causal agent of this disease. This fact accounts for a third of the total world population and it is expected that 9 million people will become infected each year. Only approximately 10% of the infected people will develop disease. However, health care workers (HCW) are continually exposed to the bacilli at endemic sites presenting increased chance of becoming sick. The objective of this work was to identify LTBI (latent tuberculosis infection) among all asymptomatic HCW of a Brazilian Central Hospital, in a three year follow up, and evaluate the humoral response among HCW with previous and recent LTBI to recombinant HspX and GlcB from M. tuberculosis. Methods Four hundred and thirty seven HCW were screened and classified into three different groups according to tuberculin skin test (TST) status: uninfected, previous LTBI and recent LTBI. ELI...
Paratuberculosis (PTB) is a chronic enteritis determined by Mycobacterium avium subsp. paratuberc... more Paratuberculosis (PTB) is a chronic enteritis determined by Mycobacterium avium subsp. paratuberculosis (Map) that affects ruminants. Three crossbred dairy cattle with clinical PTB were necropsied; tissue samples were collected and processed for histopathology and culture. Intestinal lesions were characterized in three levels of severity (mild, moderate and severe) by gross examination. Gross examination, microscopy and tissue culture were analyzed and compared. Mean tissue culture sensitivity was 66.6%. Map was recovered from 42.8% of intestinal mild lesions, 55.5% of intestinal moderate lesions, and 100% of severe intestine lesions. The results indicate a significant correlation between the level of lesions severity and the isolation of Map. KEY WORDS : Cattle, Johne’s disease, Map, paratuberculosis, pathology
Swine are susceptible to different mycobacteria species, being Mycobacterium bovis an agent of tu... more Swine are susceptible to different mycobacteria species, being Mycobacterium bovis an agent of tuberculosis, with most significant zoonotic risks, while M. avium determines a granulomatous lymphadenitis with low zoonotic risk. Currently performed intradermal tests present some important limitations, such as the lack of ability to detect anergic animals or to differentiate among mycobacterial species. In order to improve the TB diagnosis, serological assays have been developed, with encouraging results. The purpose of this study was to evaluate the performance of a MPB70-ELISA in 82 piglets divided into four groups: sensitized by inactivated M. bovis, M. avium, inoculated with oil adjuvant, or with saline solution. The test was able to discriminate between an animal sensitized by M. bovis and animals of the three other groups, including M. avium-sensitized animals; for this reason, we suggest that MPB70-ELISA could be used as a complementary tool for discriminating the agent of the m...
Microsporidia are emerging as opportunistic pathogens in patients with acquired immunodeficiency ... more Microsporidia are emerging as opportunistic pathogens in patients with acquired immunodeficiency syndrome (AIDS). Enterocytozoon bieneusi is the most commonly reported microsporidium that is detected in gastrointestinal specimens. This report describes an in situ hybridization technique with a 30-base specific synthetic DNA probe for detection of E bieneusi by light microscopy. Formalin-fixed paraffin-embedded duodenal biopsy specimens from three patients with AIDS, chronic diarrhea, and E bieneusi infection confirmed by electron microscopy were used in this study. Light microscopic examination after colorimetric detection allowed the identification of different stages of the pathogen&#39;s life cycle in the cytoplasm of enterocytes. No cross-reactivity was noted between the probe and human DNA. Our study underscores the applicability of a synthetic-labeled oligonucleotide for the detection and identification of E bieneusi in clinical samples.
The interference of bovine tuberculosis (TB) on the efficacy of paratuberculosis (PTB) diagnostic... more The interference of bovine tuberculosis (TB) on the efficacy of paratuberculosis (PTB) diagnostic tests has been evaluated. A group of 32 tuberculous cows identified by both intradermal tests and gamma-interferon assay, 16 of them confirmed by the recovery of M.bovis from tissues, was tested by three different PTB-ELISAs, being two commercials and one in-house. The rest of the adult animals of the herds, totalizing 216 TB-negative animals, were also tested as a control group. Fecal culture for PTB was negative in all animals, but seven (21.8%) tuberculous cows produced false-positive reactions when tested by various PTB-ELISAs, leading to a misdiagnosis. Tuberculosis impairs the specificity of serological tests for paratuberculosis diagnosis and should be considered for the reliability of PTB control programs.
Paratuberculosis (PTB) in Brazil has previously only been reported in imported animals and is off... more Paratuberculosis (PTB) in Brazil has previously only been reported in imported animals and is officially considered as an exotic disease. A dairy herd, which had no imported animals, presented clinically suspect animals and was investigated for paratuberculosis using faecal culture, histopathology, indirect ELISA and the agar gel immunodiffusion test. Infection with Mycobacterium avium subsp. paratuberculosis (Map) was confirmed by culture of faeces from five cows with clinical symptoms of PTB and in 7/24 randomly selected asymptomatic cows from the same herd. Two cows with clinical symptoms were necropsied and their tissues were positive for Map by culture and histopathology. Twelve asymptomatic, randomly selected cows were positive on ELISA. The results confirmed the presence of PTB in this dairy herd and for the first time demonstrated the disease in a herd of native-bred cattle in Brazil.
Bovine tuberculosis is a worldwide disease. In spite of its wide use, intradermal tuberculin reac... more Bovine tuberculosis is a worldwide disease. In spite of its wide use, intradermal tuberculin reactions present some important limitations, related to their sensitivity and specificity. The use of serological tests such as ELISA has been suggested as an alternative test for tuberculosis field diagnosis. Skin-test reactive animals are obligatorily slaughtered and, in many cases, lesions characteristic for tuberculosis are not found. In those cases, the reliability of the test may be questioned and confirmatory tests may be required. In the absence of lesions culture or histopathology becomes very difficult to perform, and ELISA might represent an alternative choice for confirmatory diagnosis. We collected blood samples from 97 skin-test reactive adult cows at slaughter. Samples were centrifuged and sera tested by ELISA-PPD using an in-house protocol previously standardized by our group (Lilenbaum et al., 1999). When lesions were found, tissue samples were collected for histopathology and M. bovis culture. Seventy animals presented lesions and histopathology confirmed the diagnosis in 63 of them, while only 35 grew M. bovis. Thirty-three animals were positive by ELISA, indicating a low sensitivity of the test, of 34.1%, and a poor agreement with skin-test (kappa index = 0.125). Although several authors reported sensitivity for ELISA in field trials as high as 90% (Ritacco et al., 1987), the rate observed in the present study was very disappointing. Therefore, due to its low sensitivity we believe ELISA should not be considered as a reliable confirmatory test for bovine tuberculosis diagnosis at the slaughter.
A herd infected naturally with tuberculosis was investigated by different diagnostic methods. Nin... more A herd infected naturally with tuberculosis was investigated by different diagnostic methods. Ninety days after a screening test that identified 21 cows as skin test positive, a Comparative Intradermal Tuberculin Test (CITT) was performed in those 21 cows and in 29 other randomly selected skin test negative cows. Milk samples and nasal swabs were collected prior to the CITT for bacteriological culture and PCR, while blood samples were collected for IFN release and antibody responses to MPB70 and MPB83, at three time points post tuberculin injection. Animals positive by CITT were slaughtered and disease confirmation undertaken. Based on the Kappa test, IFN was comparable to the standard tests (culture, PCR and CITT) at all three sampling points. Results from both antibody ELISAs were similar but were not comparable to the standard tests. T-test analysis of the CITT, IFN and ELISAs demonstrated that their performances were not correlated. There is increasing recognition that individua...
The diagnosis of bovine tuberculosis aims to identify the immune response against mycobacterial a... more The diagnosis of bovine tuberculosis aims to identify the immune response against mycobacterial antigens. Although Single Intradermal Comparative Cervical Tuberculin test (SICCT) is broadly used for first identification of the disease, the performance of ELISAs has been investigated for diagnosis improvement. The present study expected to find out the influence of intradermal skin tests on the results of ELISAs using the recombinant proteins MPB70 and MPB83 as antigens on cows from a naturally infected herd. Results were analyzed by the F-test, Mann-Whitney and Friedman tests Although comparable to both proteins, results showed that positive animals presented a tendency of augment reactivity to MPB70, representing a tendency for a booster effect, but not to MPB83.
This investigation aimed at the detection of Mycobacterium tuberculosis (MTB) in the sputum of Su... more This investigation aimed at the detection of Mycobacterium tuberculosis (MTB) in the sputum of Suruí Indian subjects from Amazonia, Brazil. Polymerase chain reaction analyses were positive for12 samples, five of which were also culture-positive (N = 147). Four MTB genotypes were identified, one of which showed resistance to rifampicin and isoniazid. The study also highlighted one village complex as of particular importance, considering the relatively high number of tuberculosis cases reported and of MTB isolates obtained.
We evaluated, for the first time in Latin America, the performance of a commercial enzyme immunoa... more We evaluated, for the first time in Latin America, the performance of a commercial enzyme immunoassay (EIA) (Calypte Biomedical Corporation, Berkeley, Calif.) that detects human immunodeficiency virus type 1 (HIV-1)-specific antibodies in urine in comparison to standard serological assays (two commercial EIAs and a commercial Western blot [WB] assay). Paired serum and urine specimens were collected from two different groups of Brazilian patients: 225 drug users with unknown HIV status who attended drug treatment centers in Rio de Janeiro, Brazil, and 135 subjects with known HIV status. Patients showing positive results in the serum EIAs and/or in the urine EIA were serologically confirmed by WB assay. For 135 individuals with known HIV status, the urine EIA showed 100% sensitivity (74 positive samples) and 95.1% specificity (58 of 61 negative specimens). For 225 drug users, the test showed 100% sensitivity (2 positive samples) and 98.7% specificity (220 of 223 negative samples) comp...
Comparative Immunology, Microbiology and Infectious Diseases, 2010
In order to demonstrate the potential to distinguish paratuberculosis (PTB) from bovine tuberculo... more In order to demonstrate the potential to distinguish paratuberculosis (PTB) from bovine tuberculosis infection (TB), ELISAs with M. bovis-specific MPB70 or MPB83 as capture antigens were developed and tested on two groups of cattle: Group A comprised 23 animals positive for Mycobacterium avium paratuberculosis (Map) and TB free. Group B comprised 48 animals from a Map free herd during the previous 5 years, but confirmed as tuberculous by positive results on PPD testing and M. bovis culture. Results demonstrated a significant difference (p < 0.01) between reactivity of sera from these groups, encouraging the study of purified proteins to differentiate between both diseases.
An in-house PPA-ELISA was compared to a commercial ELISA using a panel of 108 serum samples. In r... more An in-house PPA-ELISA was compared to a commercial ELISA using a panel of 108 serum samples. In relation to commercial test, in-house assay presented 100% of sensitivity and 83.5% of specificity and a high concordance (κ> 0.5), which demonstrates that the in-house assay is a valuable tool for use in developing countries.
Forty-four cows from five herds infected with tuberculosis (TB) and without paratuberculosis (PTB... more Forty-four cows from five herds infected with tuberculosis (TB) and without paratuberculosis (PTB), and 21 cows from a herd without either infection were studied. The cattle presented concordant results in both the skin test and γ-interferon assay for TB and two commercial ELISAs for PTB. Animals were divided according to TB test results into Group A with 28 TB-infected animals, Group B with 16 TB-negative animals from infected herds, and Group C with 21 TB-negative cows from a tuberculosis-free herd (which were used as controls). Twenty of 28 animals from Group A (71.4%), 6/16 from Group B (37.5%) and none from Group C were reactive to PTB ELISAs, suggesting that these commercial kits were unable to distinguish between PTB and TB. It is proposed that natural occurring TB strongly interferes in the diagnosis of PTB and that commercial ELISAs cannot be considered reliable tools in the diagnosis of paratuberculosis in tuberculosis-infected herds.
Paratuberculosis is a chronic enteritis that affects ruminants and is caused by Mycobacterium avi... more Paratuberculosis is a chronic enteritis that affects ruminants and is caused by Mycobacterium avium paratuberculosis (Map). The disease is worldwide spread and causes important economic losses. In Brazil, the bacillus was isolated in the south and northeast regions of the country and in Rio de Janeiro, but there are no enough epidemiological studies about its occurrence. Isolation of Map from tissues or fecal samples is 100% specific, but Map shows the most fastidious growth of all mycobacteria. Incubation lasts 8-12 weeks, with a dependency on exogenous mycobactin J. Diagnostic tests based on specific DNA sequences allow fast and secure identification, and PCR has been used to confirm positive culture results and to identify Map in feces, milk and tissues. The most frequently used target sequences are the gene encoding the 16S rRNA, and the insertion element IS900. Serological assays are widely used for the herd diagnosis of the disease. A commercial ELISA with M. phlei pre-adsorption step achieves a specificity of 95.4% to 99% and a sensitivity of about 45%. Until now, there is no effective treatment for ill animals and control programs are based on managing procedures of herds and culling of symptomatic animals. In Brazil, paratuberculosis was recently identified and has been demonstrated even in autochthonous closed herds. Therefore, it is essential to perform an epidemiological national research and to investigate the economic impact of the disease in our herds. These results could promote a control program of paratuberculosis adapted to the Brazilian requirements.
ELISAs for paratuberculosis employ a preadsorption step with Mycobacterium phlei to diminish unsp... more ELISAs for paratuberculosis employ a preadsorption step with Mycobacterium phlei to diminish unspecific reactions As M. fortuitum is one of the most frequent environmental mycobacteria, the purpose of this pilot study was to evaluate its use as an alternative for the preadsorption in ELISAs for paratuberculosis. Results suggest that M. fortuitum can be an alternative instead of or associated to M. phlei with comparable results (κ > 0.8) to conventional ELISAs using M. phlei as a preadsorption antigen.
We evaluated the performance of the AMPLICOR MTB assay for detection of M. tuberculosis in clinic... more We evaluated the performance of the AMPLICOR MTB assay for detection of M. tuberculosis in clinical specimens obtained from 98 smear-negative tuberculous patients (43 with positive and 55 with negative culture results). The sensitivity of the AMPLICOR MTB was 44.9% (44/98) and that of culture was 43.8% (43/ 98). No significant difference was observed between the results obtained by AMPLICOR MTB and by culture. We conclude that amplification assays could be used for testing smear-negative specimens because a rapid diagnosis will benefit those patients.
Background Tuberculosis (TB) remains a major world health problem. Around 2 billions of people ar... more Background Tuberculosis (TB) remains a major world health problem. Around 2 billions of people are infected by Mycobacterium tuberculosis, the causal agent of this disease. This fact accounts for a third of the total world population and it is expected that 9 million people will become infected each year. Only approximately 10% of the infected people will develop disease. However, health care workers (HCW) are continually exposed to the bacilli at endemic sites presenting increased chance of becoming sick. The objective of this work was to identify LTBI (latent tuberculosis infection) among all asymptomatic HCW of a Brazilian Central Hospital, in a three year follow up, and evaluate the humoral response among HCW with previous and recent LTBI to recombinant HspX and GlcB from M. tuberculosis. Methods Four hundred and thirty seven HCW were screened and classified into three different groups according to tuberculin skin test (TST) status: uninfected, previous LTBI and recent LTBI. ELI...
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Papers by Walter Oeleman