Molecular diagnosis of abdominal angiostrongyliasis by PCR using serum samples

Abdominal angiostrongyliasis (AA) is a zoonotic disease caused by the nematode Angiostrongylus costaricensis, which is endemic in southern Brazil. Humans become infected by ingesting third-stage (L3) larvae and are considered accidental hosts since neither eggs nor first-stage (L1) larvae are found in feces. The definitive diagnosis can be made by histopathologic examination of surgical specimens or intestinal biopsies. The present study assessed the use of PCR to carry out the molecular detection of AA from serum samples. A total of 62 human serum samples were divided into three groups: (i) 28 serum samples from human patients with presumptive histopathological diagnosis of AA; (ii) 23 serum samples from individuals with unknown serology for AA; (iii) 11 serum samples from patients that suffered from different parasitosis were included. The serum samples were initially tested by in-house indirect ELISA and then by PCR. A total of 14 samples were positive by ELISA, and 6 were positive by PCR. Six samples that were negative by ELISA were positive by PCR. Amplicons were sequenced, and Angiostrongylus DNA was confirmed. We conclude that PCR amplification can be used to confirm Angiostrongylus DNA in serum, which is especially important in cases where antibody levels are too low to be detected. It may also serve as a useful target for survey studies.

Bovine anaplasmosis as a risk factor for retained placenta, mastitis, and abomasal displacement in dairy cattle

This study aimed to evaluate the frequency of IgG antibodies against A. marginale, the occurrence of this bacterium by qPCR, and the effect of bovine anaplasmosis as a risk factor for clinical cases of retained placenta, mastitis, and abomasal displacement in dairy cattle. For that 179 Holstein cows out of three dairy herds, in the municipality of Sertão, Rio Grande do Sul, Brazil. These cows were on farms that were vulnerable to risk factors that are crucial to susceptibility among these animals to this intracellular hemoparasite. The mean seropositivity for A. marginale from the periods evaluated was 54% on farm A, 69.4% on farm B, and 27.3% on farm C. Molecular diagnosis was performed with qPCR and the mean positivity for A. marginale among the cows on farms A, B, and C in December 2017 was 34.6% (67/179). Infected animals showed clinical cases of retained placenta (6.1%), mastitis (6.1%), and abomasal displacement (0.5%). The association between positivity for anaplasmosis and these clinical cases was assessed through the odds ratio. Our results show that females with a positive qPCR assay for A. marginale had 52.48 times increased probability (OR) to develop clinical cases of retained placenta and mastitis (P < 0.001). These clinical cases negatively impact the productivity of positive females. Thus, implementing preventive and prophylactic control measures to ensure the sanitary quality of the herds is needed to avoid losses due to morbidity and mortality and diminish the economic losses suffered by farmers.

Chemoprophylaxis for babesiosis and anaplasmosis in cattle: case report

Cattle tick fever (CTF) causes significant economic losses in the livestock sector. The pathogenic action of the hemoparasites is associated with anemia, weight loss, abortion and reduced productivity, which result with animal death. Programs to prevent CTF involve several procedures, including immunization, chemoprophylaxis and use of ectoparasiticides, together with the vector control in the environment. The objective of this study was to report an acute outbreak of CTF in a group of 157 Hereford cattle from a farm without presence of the vector, that were moved to a farm in the same state with a high tick infestation (Rhipicephalus microplus). On the day before the transportation, the animals received a chemoprophylaxis with imidocarb dipropionate (3 mg/kg, SC), which was repeated 21 days after the first application. After 42 days, some animals showed signs compatible with CTF, which was confirmed through clinical examination, necropsy, histopathological and hemoparasitological analyses. The morbidity rate was 37.6% and the mortality rate was 24.8%. Calves that were recently weaned were the group most affected with the tick fever, morbidity (100% and mortality (73%). Chemoprophylaxis in association with use of ectoparasiticides was not sufficient to control the outbreak of the disease.

Synthetic gene as target to assess the sensitivity of PCR to detect Trichinella spp. larvae in meat from a non-endemic region

Trichinellosis is a zoonotic disease exotic in Brazil but commonly found worldwide including South American countries like Argentina. International trading of swine meat needs an official Trichinella-free diagnosis commonly carried out by pepsin-HCl digestion of diaphragm tissue fragments followed by microscopic examination for the presence or absence of Trichinella larvae. The easiness of this diagnostic method allows it to be performed at slaughtering plants but, in contrast, it lacks sensitivity and does not allow species differentiation, which is fundamental for determining geographical and species distribution of different genotypes. In our study, we aimed to evaluate a highly sensitive diagnostic method based on the polymerase chain reaction (PCR) that would allow us to detect and classify different species of Trichinella. Thus, we designed a synthetic gene and selected five sets of primers targeting specific regions of the Trichinella genome. The synthetic gene was cloned into a plasmid and then used to optimize PCR conditions. Using our PCR, we were able to detect 0.001 pg of the synthetic gene, which corresponded to 0.01 larvae. Then, we collected 175 samples of Suidae (domestic and wild boars) diaphragm fragments that were pooled into groups, digested with pepsin-HCl, and had the DNA extracted for analysis by PCR. The clinical samples evaluated were negative by PCR. Our results indicate that the PCR-based method might be a useful diagnostic method complementary to the pepsin-HCl digestion method currently in use, mostly in non-endemic areas.

In vitro ovicidal effect of a Senecio brasiliensis extract and its fractions on Haemonchus contortus

Background

Haemonchosis affects sheep husbandry and its treatment is often compromised due to the development of anthelminthic resistance. Plant-derived bioactive compounds have been studied as alternative to control Haemonchus contortus. The objective of this study was to evaluate the effect of Senecio brasiliensis extracts on H. contortus egg hatching and infective larvae migration.

Results

The aqueous extract from dried and fresh plant and alkaloid-enriched fraction of the previously dried leaves of S. brasiliensis inhibited H. contortus egg hatching. The main plant compound in alkaloid fraction was integerrimine, a pyrrolizidine alkaloid (PA). However, the aqueous extract from dried plant displayed higher efficacy when compared to their alkaloid enriched or non-polar fractions, meaning that, although PAs contributed to the ovicidal effect, other compounds in the plant can also contribute to their effect. Furthermore, the aqueous extract from dried plant also had higher efficacy than aqueous extract from fresh plant in larvae migration inhibition. Finally, extract from dried plant presented low in vitro cytotoxic effect.

Conclusion

Taken together our results suggest a good anthelmintic effect of S. brasiliensis, especially when aqueous extract is prepared from dried plant. Further in vivo studies should be performed focused on forms of administration of this extract in rearing sheep.

Serological detection and molecular characterization of piroplasmids in equids in Brazil

Equine piroplasmosis is a disease caused by the hemoparasites Babesia caballi and Theileria equi and is considered to be the most important parasitic infection affecting Equidae. The objective of the present study was to carry out an epidemiological molecular and serological survey for the presence of these two protozoal organisms in equids from the northwestern region of the State of Rio Grande do Sul (RS), south Brazil. For this purpose, blood samples were collected from 90 equids in the city of Passo Fundo, RS, Brazil. Those were animals used for sport activities, outdoor recreational riding, and work including cattle herding and mounted patrol. Anti-T. equi and anti-B. caballi IgG antibodies were detected in the sera of those animals by commercial ELISA kits. The molecular diagnosis of equine piroplasmosis due to T. equi or B. caballi (or both) consisted in the amplification of the 18S rRNA gene by nested PCR followed by sequencing of the amplified PCR product and sequence comparison and phylogenetic analysis of the isolates; 17 (18.9%) and 5 (5.55%) out of the 90 serum samples tested in this study were positive for T. equi and B. caballi, respectively. Piroplasmid 18S rRNA gene fragments were detected by PCR in 24.4% (22/90) of the samples analysed and shared 99-100% identity with sequences of T. equi by BLASTn. Samples for the phylogenetic analysis were divided into 2 groups. In group A, there was close phylogenetic relationship between 4 sequences and sequences previously reported along the US-Mexico border, in South Africa, and in Brazil. There was a phylogenetic proximity between 5 samples from group B and samples tested by other authors in the US and Spain. Variation of the 18S rRNA gene allowed the identification of 9 new T. equi genotypes in the geographical region studied.

Role of Immunohistochemistry in the Diagnosis of Leptospirosis in Neotropical Primates

Background: Leptospirosis is considered the most widespread zoonosis worldwide, occurring more frequently in tropical and developing regions. The aim of the present study was to detect the presence of Leptospira spp. in different primate tissues, using immunohistochemical (IHC) assays, taking advantage of the considerable number of necropsies compatible with a diagnosis of leptospirosis in neotropical primates at the Animal Pathology Laboratory (APL) of the University of Passo Fundo (UPF) in the northern region of Rio Grande do Sul.Materials, Methods & Results: Paraffin-embedded primate tissue samples were selected from necropsy examinations and subjected to IHC. The streptavidin-biotin-peroxidase method was used with diaminobenzidine chromogen (DAB) to verify immunostaining. Of the101 primates tested for Leptospira spp., 51.48% were positive; taining was distributed between lung (76.92%), liver (44.23%), and kidney (32.69%) tissue. Analysis of the combined anatomopathological verification data of the studied organs revealed a high frequency of lesions commonly observed in the tissues of animals exposed to the pathogen. For complementary diagnosis, an anti-Leptospira spp. antibody test was performed in primates at the UPF-Zoo, from which a population of the necropsied animals originated. The microscopic agglutination test (MAT) was utilized, which demonstrated 90.47% positivity in 21 individuals; sejroe and panama were the most frequent serovars.Discussion: Different intensities of tissue immunostaining were observed. Areas of fragmented or diffuse staining were considered to indicate equal positivity to that indicated by areas of staining with preserved morphology. Of 52 Leptospirapositive primates, most presented some degree of staining in lung samples, which shows a high level of involvement for this organ in primate leptospirosis. Conventional pathological diagnostic methods do not allow fort issue antigen recognition, thus making the IHC technique important to facilitate conclusive antigen sample verification. In the liver, leptospires were detected mostly between the sinusoids, hepatocytes, and Kupffer cells. In kidney tissues, staining indicated small agglomerates in the tubular lumen, interstitium, and glomeruli. All these forms of presentation have been previously reported. Considering that we detected the highest number of positive samples in lung tissue, followed by those from liver and kidney tissue, we argue that the IHC technique, when applied to samples of these three tissues, decreases the chance of false negatives. Anatomopathological studies of primate leptospirosis are scarce. In dogs, renal lesions are characterized by the necrosis and degeneration of tubular epithelium, cellular debris, and hyaline cylinders. In the liver, hepatocyte cord dissociation and biliary pigment accumulation within the canaliculi and hepatocellular necrosis are observed. These findings are similar to those from our study. In the lung, diffuse alveolar lesions are reported, with hemorrhage and edema, in addition to capillaritis. The high frequency of Leptospira-positive animals determined by serological examination was consistent with the IHC findings, thus confirming the pathogen’s high prevalence in neotropical primate populations in the studied region. Serological surveys on primate populations have already been carried out and have revealed frequency and serovar variations between regions. Immunohistochemical examination allows the detection of leptospires in various tissues and should be used based on the characteristics of the investigated case.

Rangelia vitalii, Babesia spp. and Ehrlichia spp. in dogs in Passo Fundo, state of Rio Grande do Sul, Brazil

Abstract Pathogens transmitted by ticks are an emerging problem worldwide, this study aimed to diagnose the causal agents of infection in dogs presenting suspected hemoparasitoses. Fifty-eight dogs with clinical signs such as depression, hemorrhagic diathesis and fever were evaluated regarding clinical presentation, hemogram, blood smears and serological tests, using the indirect immunofluorescence method for the agents Babesia vogeli and Ehrlichia canis and conventional PCR for Babesia spp. (gene 18S rRNA), Rangelia vitalii (gene 18S rRNA) and Ehrlichia spp. (gene dsb). Five (8.6%) of the 58 dogs were serologically positive for Babesia spp. and three (5.1%) for E. canis. Four dogs (6.8%) were positive for R. vitalii through the molecular diagnosis. The PCR products were sequenced and the DNA from R. vitalii was found to be 99% genetically identical to samples of R. vitalii that had been isolated in Brazil. No presence of Babesia spp. or E. canis was observed through PCR on the dogs evaluated here. The results indicate the presence of R. vitalii and exposure to Babesia spp. and Ehrlichia spp. among the dogs analyzed.

Re-emergence of Chorioptes bovis (Acari: Psoroptidae) in cattle in the state of Rio Grande do Sul, Brazil

Here we describe an outbreak of chorioptic mange in cattle, 56 years after its first identification in Brazil. Between the months of June and July 2011, dermatitis characterized by alopecia and crusted and thickened skin at the insertion of the tail and in the ischiorectal fossa was recognized in 40 (35.7%) out of 112 Holstein cows on a farm in the northeastern mesoregion of the state of Rio Grande do Sul, Brazil. After diagnosing mange caused by Chorioptes bovis, the cows were weighed and treated with 0.5% ivermectin, as a pour-on single dose, and were separated into two groups: cows in early lactation and those in late lactation. The survival rate of C. bovis and the healing rate in the two groups of infested cows were monitored every seven days through skin scrapings. After 28 days of evaluation, the cure rate through treatment was greater among cows in early lactation (p <0.0001). The survival rate of C. bovis was higher in cows in late lactation.