Neorickettsia helminthoeca in dog, Brazil

Neorickettsia sp. in coatis (Nasua nasua) in Brazil

The genus Neorickettsia comprises trematode-associated bacteria that can cause diseases in animals and humans. Despite detection of Neorickettsia antigens in the intestine of coatis kept in captivity in southern Brazil through immunohistochemistry, the molecular identity of the bacteria in South American procyonids remains elusive. The aim of the present study was to investigate the occurrence of Neorickettsia sp. in blood samples from coatis in central-western Brazil. Between March 2018 and January 2019, animals were captured and recaptured in two areas of the Cerrado (Parque Estadual do Prosa, PEP; and Vila da Base Aérea, VBA) located in the city of Campo Grande, state of Mato Grosso do Sul, central-western Brazil. All captures were performed according to convenience. DNA from 97 blood samples was subjected to nested PCR (nPCR) targeting a fragment of the 16S rRNA gene of Neorickettsia sp. Six samples (3.6%; five from VBA and one from PEP) from different coatis were positive in nPCR based on the 16S rRNA. The sequences obtained (~500 bp) showed ˃ 99% similarity to N. risticii. Phylogenetic analysis clustered the sequences detected in the present study in a clade with N. risticii. This is the first molecular detection of Neorickettsia sp. in coatis in Brazil.

Molecular and serological detection of arthropod-borne pathogens in carnivorous birds from Brazil

Rickettsiales, Haemosporida and Rhizobiales agents can cause diseases that affect various animal species, including humans. Due to predation behaviour, carnivorous birds may play an important role in spreading these etiological agentes across geographically distant areas, specially if they are migratory. The aim of this study was to investigate the occurrence and to access the phylogenetic relations among Anaplasmataceae (Ehrlichia, Anaplasma, Neorickettsia), Bartonellaceae (Bartonella spp.), and Haemosporida (Plasmodium, Haemoproteus and Leucocytozoon) agents in blood samples from 121 carnivorous birds sampled in the states of São Paulo and Rio de Janeiro, Brazil. Inclusions resembling hemoparasites were not observed in Giemsa-stained preparations. While three animals were seropositive for E. chaffeensis (3.41% [3/88]; 95% CI:1.17-9.55%), five showed antibodies to A. phagocytophilum (5.68% [5/88]; 95% CI: 2.45-12.62%). Despite the detection of rrs gene fragments closely related to E. chaffeensis (4.13% [5/121]; 95% CI: 1.78-9.31%), no positivity was observed in the qPCR based on the genes vlpt for the organism. Similarly, 12 (9.91% [12/121]; 95% CI: 5.76-16.74%) samples were positive in the qPCR for Anaplasma spp. based on groEL gene, but negative in the qPCR for A. phagocytophilum based on msp-2 gene. Three samples were positive in the nPCR for E. canis based on rrs gene. Three samples were positive for Haemoproteus spp. and one for Plasmodium spp. in the nPCR based on cytB gene. Four birds (3.3% [4/121]; 95% CI: 1.29-8.19%) presented co-positivity by Ehrlichia sp. and Anaplasma sp. in molecular assays. One (0.82% [1/121]; 95% CI:0.15-4.53%) bird showed to be seropositive for E. chaffeensis and and positive in PCR for Haemoproteus sp. All birds were negative in the qPCR assay for Bartonella spp. (nuoG). The present work showed the occurrence of Anaplasmataceae agents and hemosporidians in carnivorous birds from southeastern Brazil. The role of these animals in the dispersion of Anaplasmataceae agents should be further investigated.

Neorickettsia helminthoeca associated lymphoid, enteric, and pulmonary lesions in dogs from Southern Brazil: An immunohistochemical study

Neorickettsia helminthoeca (NH), the agent of salmon poisoning disease or canine neorickettiosis (CN), is a bacterial endosymbiont of the nematode Nanophyetus salmincola, and infections are spreading among specific fish-eating mammalians. This article describes the pathologic and immunohistochemical findings associated with spontaneous NH-induced infections in dogs from Southern Brazil. The principal pathologic findings were hypertrophy of Peyer patches and lymphadenopathy with lymphocytic proliferation, chronic interstitial pneumonia, and chronic enteritis associated with positive intralesional immunoreactivity to antigens of NH within macrophages and histiocytes. Positive immunoreactivity against canine parvovirus-2 (CPV-2) or/and canine distemper virus was not detected in the evaluated intestinal segments or in the samples from the cerebellum and lungs, respectively, from the dogs evaluated. These findings demonstrated that NH was involved in the enteric, pulmonary, and lymphoid lesions herein described, and provide additional information to confirm the occurrence of this bacterial endosymbiont within this geographical location. It is proposed that chronic pneumonia should be considered as a pathologic manifestation of NH-induced infections. Additionally, our results show that the occurrences of CN seem to be underdiagnosed in Southern Brazil due to the confusion with the incidence of CPV-2.

Analysis of complete genome sequence and major surface antigens of Neorickettsia helminthoeca, causative agent of salmon poisoning disease

Neorickettsia helminthoeca, a type species of the genus Neorickettsia, is an endosymbiont of digenetic trematodes of veterinary importance. Upon ingestion of salmonid fish parasitized with infected trematodes, canids develop salmon poisoning disease (SPD), an acute febrile illness that is particularly severe and often fatal in dogs without adequate treatment. We determined and analysed the complete genome sequence of N. helminthoeca: a single small circular chromosome of 884 232 bp encoding 774 potential proteins. N. helminthoeca is unable to synthesize lipopolysaccharides and most amino acids, but is capable of synthesizing vitamins, cofactors, nucleotides and bacterioferritin. N. helminthoeca is, however, distinct from majority of the family Anaplasmataceae to which it belongs, as it encodes nearly all enzymes required for peptidoglycan biosynthesis, suggesting its structural hardiness and inflammatory potential. Using sera from dogs that were experimentally infected by feeding with parasitized fish or naturally infected in southern California, Western blot analysis revealed that among five predicted N. helminthoeca outer membrane proteins, P51 and strain‐variable surface antigen were uniformly recognized. Our finding will help understanding pathogenesis, prevalence of N. helminthoeca infection among trematodes, canids and potentially other animals in nature to develop effective SPD diagnostic and preventive measures. Recent progresses in large‐scale genome sequencing have been uncovering broad distribution of Neorickettsia spp., the comparative genomics will facilitate understanding of biology and the natural history of these elusive environmental bacteria.

Molecular and serological detection of tick-borne pathogens in dogs from an area endemic for Leishmania infantumin Mato Grosso do Sul, Brazil

Tick-borne pathogens affect a wide range of vertebrate hosts. To identify tick-borne pathogens among dogs from Campo Grande, MS, Brazil testing seropositive for Leishmania infantum (syn. L. chagasi), a serological and molecular study was conducted to detectEhrlichia canis, Anaplasma platys and Babesia vogeli in 60 serum and spleen samples. A confirmatory diagnosis ofL. infantum based on serological and molecular assays was also performed, as was sequence alignment and phylogenetic analysis to assess the identity of the parasite species infecting these animals. IgG antibodies toEhrlichia spp., B. vogeli and L. infantum were found, respectively, in 39 (65%), 49 (81.6%) and 60 (100%) of the sampled dogs. Twenty-seven (45%), fifty-four (90%), fifty-three (88.3%), two (3.3%) and one (1.6%) dog were positive, respectively, forE. canis, Leishmania spp., Leishmania donovani complex, Babesia sp. and Anaplasma sp. in PCR assays. After sequencing, the amplicons showed 99% of identity with E. canis, B. vogeli, A. platys andLeishmania chagasi isolates. The findings of this study indicate that L. infantum-seropositive dogs from Campo Grande are exposed to multiple tick-borne pathogens, which should therefore be included in the differential diagnosis of dogs with clinical suspicion of leishmaniasis.

Migratory and carnivorous birds in Brazil: reservoirs for Anaplasma and Ehrlichia species?

In order to investigate new hosts for Anaplasmataceae agents in Brazil, we collected blood samples from 21 wild birds. Using molecular techniques, we detected the presence of Anaplasma phagocytophilum, Ehrlichia chaffeensis, and an Ehrlichia species closely related to Ehrlichia canis in carnivorous avian blood samples. In addition, an Ehrlichia species closely related to an Ehrlichia species found in wild felines in Brazil was also detected in a goose blood sample. Wild birds may play a role as carriers of Anaplasmataceae agents in Brazil.

Neorickettsia helminthoeca and salmon poisoning disease: a review

Neorickettsia helminthoeca is an obligate intra-cytoplasmic bacterium that causes salmon poisoning disease (SPD), an acute, febrile, fatal disease of dogs. The complex life-cycle of this pathogen involves stages in an intestinal fluke (Nanophyetus salmincola), a river snail (Oxytrema silicula), in fish, and in fish-eating mammals. This complexity has created confusion with respect to the various bacterial and parasitic infections associated with the disease and its significance in dogs in specific geographical locations has likely to have previously been under-estimated. This paper addresses the history, taxonomy, microbiology of N. helminthoeca and summarises the pathogenesis, clinical signs and pathological features associated with infection. Furthermore, the biological cycles, treatment, control, and both public and veterinary health impacts associated with this pathogen and the intestinal fluke N. salmincola are discussed.