The concerns that are raised by Peacock and others1 about caution against the use of an unvalidated enzyme-linked immunosorbent assay (ELISA) are critically important. The aim of our work was to perform a serological study in some regions of Ceará, Brazil, where culture-confirmed cases of melioidosis had been reported2 and where bacteria has been isolated from the soil.3 We thank Dr. Peacock for his kind letter1 and agree with his assessment that there is a risk of false positive results with any serological method. We considered this possibility in our data and mentioned it in our discussion.4 We remind the authors that we used a culture filtrate of B. pseudomallei, as recommended by others.5
We just reinforce that our work aimed to draw attention to the need to establish an epidemiological surveillance for cases of melioidosis in northeastern Brazil, where the disease is still unknown. We agree with the authors that the indirect hemagglutination assay (IHA) method is a valid and widely used technique, and endorse their call for an international serological standard. In the meantime, we intend to establish the IHA method as an interim measure to allow comparison with results from other centers.
Peacock SJ, Cheng AC, Currie BJ, Dance DA, 2011. The use of positive serological tests as evidence of exposure to Burkholderia pseudomallei. Am J Trop Med Hyg 84: 1021.
Rolim DB, Vilar DC, Sousa AQ, Miralles IS, Oliveira DC, Harnett G, O'Reilly L, Howard K, Sampson I, Inglis TJ, 2005. Melioidosis, northeastern Brazil. Emerg Infect Dis 11: 1458–1460.
Rolim DB, Rocha MF, Brilhante RS, Cordeiro RA, Leitão-Junior N, Inglis TJ, Sidrim JJ, 2009. Environmental isolates of Burkholderia pseudomallei in Ceará State, northeast Brazil. Appl Environ Microbiol 75: 1215–1218.
Rolim DB, Vilar DC, Cavalcanti LP, Freitas LB, Inglis TJ, Rodrigues JL, Nagao-Dias AT, 2011. Burkholderia pseudomallei antibodies in individuals living in endemic regions in northeastern Brazil. Am J Trop Med Hyg 84: 302–305.
Chentamarakshan V, Vadivelu J, Puthucheary SD, 2001. Detection of immunoglobulins M and G using culture filtrate antigen of Burkholderia pseudomallei. Diagn Microbiol Infect Dis 39: 1–7.