Patologia e caracterização molecular de Neorickettsia Helminthoeca em cães no Brasil

AUTOR(ES)
DATA DE PUBLICAÇÃO

2006

RESUMO

Neorickettsia helminthoeca, an intracellular obligate bacterium, is the cause of salmon poisoning disease (SPD) of canids. The digenean trematode, Nanophyetus salmincola, is the vector of the bacterium, which maintains the pathogen throughout its entire life cycle, that includes a river snail (Oxytrema silicula), fishes (principally, salmon and trout), and canids (dogs and other fish-eating mammals). The snail, O. silicula, is endemic only in certain rivers of the Pacific Northwest of the USA which has resulted in the restricted occurrence of SPD. This study describes the pathological alterations and the molecular findings associated with N. helminthoeca in Brazilian dogs. During 2001 to 2005, 20 adult dogs (5, mongrels; 15 Beagles), of both sexes, from the city of Maringá, Paraná, demonstrated gross and histological alterations consistent with those described in SPD. Gross lesions were characterized by generalized lymphadenopathy, predominantly at the mesenteric, pre-scapular, and popliteal lymph nodes, with several white follicles randomly distributed at the cortical zone; severe hypertrophy of intestinal Peyer?s patches and intestinal lymphoid tissue; intestinal hemorrhage, and splenomegaly. Microscopic evaluation of lymph nodes lesions revealed severe cortical edema and depletion, and proliferation of reticuloendothelial cells associated with intracytoplasmic neorickettsial organisms within reticuloendothelial cells. Intestinal lesions were characterized by severe hyperplasia of lymphoid tissue, hemorrhage, and congestion with intralesional intracytoplasmic neorickettsial organisms in reticuloendothelial cells. These organisms were readily demonstrable by Giemsa staining. Selected tissues (lymph node, intestine, spleen, and liver) from 10 Beagles were harvested aseptically and processed for PCR evaluation, cloning, sequencing, and phylogenetic analyses. N. helminthoeca was confirmed by PCR using Neorickettsia genus-specific 16S ribosomal RNA (rrs) primers in two dogs (Maringá 1, mesenteric lymph node; Maringá 2, Peyer?s path); these dogs were also positive by PCR for the RNA polymerase ?-subunit (rpoB) and the heat shock protein (groESL) genes of N. helminthoeca. The DNA nucleotide sequences of the N. helminthoeca Maringá 1 dog were 100% identical to that of the N. helminthoeca sequences deposited in GenBank for the rrs, rpoB, and groESL genes. This is the first description of N. helminthoeca and SPD beyond the endemic region of the Northwest Pacific States of the USA, and Canada. The method of transmission-infection and the biological life cycle associated with N. helminthoeca in Brazil are currently unknown.

ASSUNTO(S)

helminths dogs - diseases helminto cão - doenças

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