Current status of glanders in Brazil: recent advances and challenges

Glanders is a zoonotic disease caused by Burkholderia mallei that affects equidae. After its re-emergence in Brazil the disease has been reported in almost all country. The control strategy established by the Ministry of Agriculture, Livestock and Supply (MAPA) involves statutory testing for equidae trafic control, movement restrictions and culling of positive animals from the detected outbreaks. These measures are based on the results of serological tests performed by private laboratories accredited by MAPA or by official MAPA laboratories. The complement fixation (CF) test is prescribed as screening and western blotting (WB) as a confirmatory test. The major problems for the diagnosis of glanders in Brazil are technological dependence, the quality of certain antigens, as well as the limitations of the screening test (CF), with low sensitivity (Se) and specificity (Sp), and the subjectivity of the WB. Alternatively, we have developed an indirect ELISA (ELISAi) employing antigens of B. mallei isolated in Brazil (Diagnostic kit – Glanders iELISA; MAPA License n: 10.080/2015). The ELISAi showed Se and Sp of 98.76% and 99.65%, respectively. The Kit will be submitted to international validation (OIE-Tender ref. AD/SR/2015/1885). The next step to complete the validation in Brazil is the conduction of reproductibility assay. Then it is expected that the ELISAi will be included in the Equidae National Health Program as official test for serological diagnosis of glanders.

Métodos de diagnóstico e estratégias de controle do mormo no brasil

Molecular detection of Burkholderia mallei in different geographic regions of Brazil

ABSTRACT: Glanders is a disease caused by the bacterium Burkholderia mallei that primarily affects horses, mules and donkeys. The disease can cause lesions in the skin, lungs and several other organs. However, it often manifests as an asymptomatic disease. In Brazil, serological tests of high sensitivity and specificity are used to assist in the detection of antibodies against B. mallei and to contribute to the control of the disease. However, due to the mandatory euthanasia of seroreactive animals, equids with positive serology for B. mallei and asymptomatic generated great conflicts between breeders, veterinarians and diagnostic laboratories. This study clarifies the limitations of complementary diagnostic tests for detecting B. mallei. It describes the clinical, morphological and laboratory findings in 24 equines from different municipalities in the Mato Grosso State, Brazil, which reacted to the complement fixation test and were positive in the western blotting test for glanders. Data and tissue samples were collected from 24 horses for histological, microbiological and molecular analysis. In 23 horses, no clinical signs, morphological alterations, microbiological isolation, or molecular detection would characterize B. mallei infection. On the other hand, samples from an asymptomatic horse without lesional alterations showed sequence amplification compatible with B. mallei in the PCR. Considering that the infection by B. mallei is subject to the application of animal sanitary defense measures and that, by international requirement and national legislation, the serological results are tools that should support the sanitation procedures for the error of the bacteria in the Mato Grosso State, Brazil.

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Pathology, microbiology, and molecular evaluation of tissues from equids serologically positive for Burkholderia mallei in Midwestern Brazil

Glanders is an infectious and often lethal zoonotic disease of equines caused by the bacterium, Burkholderia mallei. This condition is characterized by respiratory, lymphatic, and cutaneous lesions. In this study, we monitored the development of clinical symptoms in animals naturally infected with B. mallei across different equine breeds and also isolated and characterized the disease-causing bacteria. We studied two official glanders outbreaks in the state of Alagoas, Brazil. During the outbreaks, we performed clinical and immunological follow-up of the animals, as well as euthanasia and anatomopathological examination. We also collected diagnostic materials for isolative, phenotypic, molecular, and biological testing. We did not observe any clinical patterns of glanders among animals infected with the same strain of B. mallei. Based on our results, we suggest that early diagnosis of infection should be made through highly sensitive and specific immunoassays. In asymptomatic but positive test cases, we confirmed the importance of conducting pathological, microbiological, and molecular examinations.

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Luiz André Rodrigues de Lima

Papers

Monitoring the outbreak of equine glanders in Alagoas, Brazil: Clinical, immunological, molecular, and anatomopathological findings