ABSTRACT OBJECTIVE To evaluate the performance of post mortem laboratory analysis in identifying the causes of hemorrhagic fever and/or neuroinvasive disease in deaths by arbovirus infection. METHODS Retrospective cross-sectional study based on the differential analysis and final outcome obtained in patients whose samples underwent laboratory testing for arboviruses at the Pathology Center of the Adolfo Lutz Institute, in São Paulo, Brazil. RESULTS Of the 1355 adults clinically diagnosed with hemorrhagic fever and/or neuroinvasive disease, the most commonly attributed cause of death and the most common final outcome was dengue fever. Almost half of the samples tested negative on all laboratory tests conducted. CONCLUSION The failure to identify the causative agent in a great number of cases highlights a gap in the diagnosis of deaths of unknown etiology. Additional immunohistochemical and molecular assessments need to be added to the post-mortem protocol if all laboratory evaluations performed fail to identify a causative agent. While part of our findings may be due to technical issues related to sample fixation, better information availability when making the initial diagnosis is crucial. Including molecular approaches might lead to a significant advancement in diagnostic accuracy.

ABSTRACT OBJECTIVE To evaluate the performance of post mortem laboratory analysis in identifying the causes of hemorrhagic fever and/or neuroinvasive disease in deaths by arbovirus infection. METHODS Retrospective cross-sectional study based on the differential analysis and final outcome obtained in patients whose samples underwent laboratory testing for arboviruses at the Pathology Center of the Adolfo Lutz Institute, in São Paulo, Brazil. RESULTS Of the 1355 adults clinically diagnosed with hemorrhagic fever and/or neuroinvasive disease, the most commonly attributed cause of death and the most common final outcome was dengue fever. Almost half of the samples tested negative on all laboratory tests conducted. CONCLUSION The failure to identify the causative agent in a great number of cases highlights a gap in the diagnosis of deaths of unknown etiology. Additional immunohistochemical and molecular assessments need to be added to the post-mortem protocol if all laboratory evaluations performed fail to identify a causative agent. While part of our findings may be due to technical issues related to sample fixation, better information availability when making the initial diagnosis is crucial. Including molecular approaches might lead to a significant advancement in diagnostic accuracy.

Resumo Um lobo-marinho-subantártico (Arctocephalus tropicalis) juvenil foi achado morto no Estado de Santa Catarina, sul do Brasil, apresentando pneumonia parasitária disseminada por Parafilaroides sp. Infecção concomitante por dois gammaherpesvírus diferentes foi identificada pela PCR em diversos tecidos, um desses herpesvírus possivelmente uma nova espécie (denominada provisoriamente Otariid herpesvirus 7). DNA de Sarcocystis sp. foi identificado molecularmente em amostras de músculo esquelético que apresentavam bradizoítos intra-sarcoplasmáticos sem aparente resposta tecidual. Todas as amostras analisadas (linfonodo mandibular, laríngeo, traqueal e mesentérico, e pulmão) pela PCR para Brucella spp. foram negativas. A causa mais provável da morte do animal foi parafilaroidose pulmonar severa. O papel patogénico dos gammaherpesvírus em vários tecidos não foi evidente. Este estudo descreve a patogenicidade de Parafilaroides sp. em um lobo-marinho-subantártico, amplia a variedade de hospedeiros de herpesvírus em pinípedes e reporta a primeira identificação molecular de Sarcocystis sp. para essa espécie.

Abstract A juvenile subantarctic fur seal (Arctocephalus tropicalis) found dead in Santa Catarina state, southern Brazil, presented with disseminated verminous pneumonia due to Parafilaroides sp. A concomitant infection with two different gammaherpesviruses was identified by PCR in different tissues; one of them possibly a novel species (tentatively named Otariid herpesvirus 7). Sarcocystis sp. DNA was identified molecularly in skeletal muscle samples with intrasarcoplasmic bradyzoites and no apparent tissue response. All analyzed samples (mandibular, laryngeal, tracheal, and mesenteric lymph nodes, and lung) were PCR-negative for Brucella spp. The most likely cause of death was severe pulmonary parafilaroidiasis. The pathogenic role of the gammaherpesviruses in several of the tissues was not evident. This study describes the pathogenicity of Parafilaroides sp. in a subantarctic fur seal, widens the host range of herpesvirus in pinnipeds, and reports the first molecular identification of Sarcocystis sp. in this species.