Viroj Wiwanitkit
Wiwanitkit House, Bangkhae, Bangkok, Thailand
Dear Editor,
Sir, I read the recent report on atypical lymphocytosis in leptospirosis with a great interest1. Damasco et al concluded that atypical leukocyte subsets are associated with partial protection during the disease course of leptospirosis“1. Some points should be discussed. First, as a nature of retrospective study, there can be many pitfalls. The detection of atypical lymphocytosis is usually problematic if there is no expert medical technologist control the quality of analysis2. For sure, the retrospective study cannot control the quality of the laboratory analysis. Second, as Damasco et al mentioned, several diseases can mimic leptospirosis. An important disease that can present atypical lymphocytosis is dengue infection. This infection is also common in the studied setting. The question is whether the diagnosis of leptospirosis is correct. Also, the co-infection between leptospirosis and dengue can be possible3 and this cannot be ruled out in this work.
REFERENCES
1. Damasco PV, Avila CA, Barbosa AT, Ribeiro Carvalho MM, Pereira GM, Lemos ER, et al. Atypical lymphocytosis in leptospirosis: a cohort of hospitalized cases between 1996 and 2009 in State of Rio de Janeiro, Brazil. Rev Soc Bras Med Trop 2011;44:611-615. [ Links ]
2. Koepke JA, Dotson MA, Shifman MA. A critical evaluation of the manual/visual differential leukocyte counting method. Blood Cells 1985;11:173-186. [ Links ]
3. McGready R, Ashley EA, Wuthiekanun V, Tan SO, Pimanpanarak M, Viladpai-Nguen SJ, et al. Arthropod borne disease: the leading cause of fever in pregnancy on the Thai-Burmese border. PLoS Negl Trop Dis 2010;4:e888. [ Links ]
Address to:
Dr. Viroj Wiwanitkit
Wiwanitkit House, Bangkhae, 10160 Bangkok Thailand
Phone: 668 7097-0933
email: somsriwiwan@hotmail.com
Received in 02/12/2011
Accepted in 13/01/2012
Authors reply: atypical lymphocytosis in leptospirosis: acohort of hospitalized cases between 1996 and 2009 in state of Rio de Janeiro, Brazil
Resposta dos autores: linfócitos atípicos na leptospirose:coorte depacientes hospitalizados entre 1996 e 2009, no estado do Rio de Janeiro, Brasil
Paulo Vieira DamascoI; Carlos André Lins ÁvilaI; Angélica Tápia BarbosaI; Marilza de Moura Ribeiro CarvalhoII; Geraldo Moura Batista PereiraII,III; Elba Regina Sampaio de LemosIV; Márcio Neves BóiaI; Martha Maria PereiraV
IDisciplina de Doenças Infecciosas e Parasitárias, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, RJ
IILaboratório de Imunopatologia, Universidade do Estado do Rio de Janeiro, Rio de Janeiro, RJ
IIILaboratório de Microbiologia, Fundação Oswaldo Cruz, Rio de Janeiro, RJ
IVLaboratório de Hantaviroses e Rickettioses, Fundação Oswaldo Cruz, Rio de Janeiro, RJ
VLaboratório de Referência Nacional para Leptospirose, Centro Colaborador da Organização Mundial da Saúde, Fundação Oswaldo Cruz, Rio de Janeiro, RJ
Dear Editor,
We thank Prof. Wiwanitkit for his critical evaluation and comments. We agree with the observation that there are limitations in retrospective studies. However, we must clarify some aspects regarding the main issues raised. As a routine procedure, the protocols for laboratorial confirmation of clinical suspicions involve collaboration with the department of hematology at the same university and three reference laboratories accredited by the Ministry of Health, Brazil. The reference laboratories for leptospirosis, dengue, hantavirus, and ricketsiosis are located at the Instituto Oswaldo Cruz, Fundação Oswaldo Cruz (IOC/FIOCRUZ), Rio de Janeiro. All laboratories involved comply with standards of quality management procedures. The above-mentioned accreditations, protocols, and partnerships already existed at the time in which the patients were examined, diagnosed, and treated-although in retrospect regarding the analysis of the published data in this paper. The criterion to consider the presence of morphologically atypical lymphocytes was the observation of enlarged lymphocytes with abundant cytoplasm, vacuoles, and indentations of the cell membrane. The main serological test for leptospirosis was the microscopic agglutination test (MAT), considered to be the gold standard in the World Health Organization/International Leptospirosis Society guidelines, 2003. The MAT and polymerase chain reaction tests were performed in the national reference laboratory for leptospirosis in Brazil. A total of 14 of 27 cases were simultaneously tested for dengue, hantavirus, spotted fever group, and rickettsia when these diagnostic possibilities were considered at the first clinical presentation. The results were negative for those infections and positive for leptospirosis. Although the occurrence of dengue and leptospirosis is an important epidemiological aspect in the region, the concomitant infection in individual cases is considered to be rare or uncommon. It seems to be also true as a general picture considering the available data of the international literature. It should be stressed that the two cases with increased frequency of γδT-lymphocytes were positive for leptospirosis showing negative results to the dengue fever tests. We believe the additional information is sufficient to answer questions about the diagnosis. The manuscript does not state categorically the possibilities or predictions, but it raises a hypothesis that is well grounded in reliable data, to be confirmed by further prospective studies.
Address to:
Dr. Paulo Vieira Damasco
DIP/FCM/HUPE/UERJ
Av. Prof. Manoel de Abreu 444/2º andar, Vila Isabel
20550-170 Rio de Janeiro, RJ, Brasil
Fax: 55 21 2587-6323
e-mail: damascopv@ig.com.br
Received in 13/12/2011
Accepted in 13/01/2012
