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The present study evaluated the infection of opossums (Didelphis aurita) by Rickettsia rickettsii and their role as amplifier hosts for horizontal transmission of R. rickettsii to Amblyomma cajennense ticks. Three groups of opossums were evaluated: on day 0, group 1 (G1) was inoculated intraperitoneally with R. rickettsii; group 2 (G2) was infested by R. rickettsii-infected ticks; and group 3 (G3) was the uninfected control group. Opossum rectal temperature was measured daily. Blood samples were collected every 2 to 4 days during 30 days, and used to (1) inoculate guinea pigs intraperitoneally; (2) extract DNA followed by real-time polymerase chain reaction (PCR) targeting the rickettsial gene gltA; (3) study hematology; (4) detect R. rickettsii-reactive antibodies by indirect immunofluorescence assay (IFA). Blood was also collected every 10 days from days 30 to 180, to be tested by serology. Opossums were infested by uninfected A. cajennense larvae and nymphs from days 3 to 15. Engorged ticks were collected and allowed to molt in an incubator. Thereafter, the subsequent flat ticks were allowed to feed on uninfected rabbits, which were tested for seroconversion by IFA. Samples of flat ticks were also tested by real-time PCR. All G1 and G2 opossums became infected by R. rickettsii, as demonstrated by realtime PCR or/and guinea pig inoculation, but they showed no clinical abnormality. Rickettsemia was first detected at days 2 to 8, lasting intermittently till days 1 to 30. Approximately 18% and 5% of the flat ticks previously fed on G1 and G2 opossums, respectively, became infected by R. rickettsii, but only the rabbits infested with G1-derived ticks seroconverted. The study demonstrated that R. rickettsii was capable of infecting opossums without causing illness and developing rickettsemia capable of causing infection in guinea pigs and ticks, although the infection rate in ticks was low.

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Abstract. An aflatoxicosis outbreak affected 65 dogs from 9 different farms after they were fed diets with cooked corn meal as a common ingredient. Of the dogs, 60 died. Numerous dogs died on additional farms, but those dogs were not included in the study. The farmers acquired the contaminated maize products, in the form of whole corn grain or as corn meal, from the same supplier. The corn product was mixed with meat that was left over from home or commercial rations to form corn polenta, which was fed to the dogs. Necropsy was performed on 3 dogs. Two of the dogs died after a few days of refusing food, showing anorexia, polydipsia, icteric mucous membranes, hematemesis, hematochezia, or melena, and bleeding of the skin, eye, ear, and mouth. The primary necropsy findings included jaundice, hemorrhages in several organs, and yellowish enlarged liver with enhanced lobular pattern. The dog that experienced chronic ascites had a yellowish liver with reduced volume, irregular surface, and increased consistency. The main histological findings included hepatocyte fatty degeneration, biliary duct hyperplasia, cholestasis and, in the chronic case, hepatic fibrosis. High-performance liquid chromatography analysis of the corn meal from 2 affected farms revealed 1,640 ppb and 1,770 ppb of aflatoxin B 1 , respectively. The current study demonstrates an additional way that dogs can be exposed to, poisoned, and killed by aflatoxin.

RESUMO.-[Infecção fatal por Herpesvirus simplex Tipo 1 (HHV-1) em saguis de cativeiro (Callithrix jacchus and Callithrix penicillata) no Brasil: caracterização clínica e patológica.] Infecção fatal por Herpesvirus simplex Tipo 1 (HHV-1) foi diagnosticada em 12 saguis de cativeiro (Callithrix jacchus e Callithrix penicillata) provenientes da região metropolitana de São Paulo, Estado de São Paulo. Os sinais clínicos foram variáveis entres os casos, no entanto, a maioria dos saguis afetados apresentavam sinais associados à replicação viral em epitélios: úlceras na cavidade oral, lín-gua e pele da face e hipersalivação; e no sistema nervoso central: prostração, convulsão e comportamento agressivo. Histologicamente, o principal achado foi meningoencefalite necrosante não supurativa difusa, leve a acentuada com gliose, vasculite e necrose neuronal. Inclusões intranucleares também foram observadas em encéfalo, cavidade oral, pele, glândula adrenal e plexo mioentérico. A imuno-histoquímica anti-HHV-1 confirmou a presença do antígeno viral em associação às lesões em encéfalo, mucosa oral e lingual, pele da face, glândula adrenal e plexo mioentéri-co. Em 7/8 saguis infectados foi detectada a presença de HHV-1 por reação em cadeia da polimerase (PCR) a partir de amostras de encéfalo. Conclui-se que HHV-1 causa uma infecção disseminada e fatal em saguis. Clinical signs were variable among the cases, but most affected marmosets presented signs associated with viral epithelial replication: oral, lingual and facial skin ulcers and hypersalivation, and viral replication in the central nervous system: prostration, seizure and aggressive behavior. Consistent microscopic findings were diffuse mild to severe nonsuppurative necrotizing meningoencephalitis with gliosis, vasculitis and neuronal necrosis. Additionally, in the brain, oral cavity, skin, adrenal gland and myoenteric plexus intranuclear inclusion bodies were present. Immunohistochemistry confirmed the presence of the HHV-1 antigen in association with lesions in the brain, oral and lingual mucosa, facial skin, adrenal gland and myoenteric plexus. HHV-1-specific polymerase chain reaction (PCR) analysis of the brain was carried out and the virus was detected in 7/8 infected marmosets. It is concluded that HHV-1 causes widespread fatal infection in marmosets.