Rapid detection of Bovicola ovis using colourimetric loop-mediated isothermal amplification (LAMP): a potential tool for the detection of sheep lice infestation on farm.

The sheep body louse, Bovicola ovis (B. ovis), is one of the most significant ectoparasites affecting Australia's sheep flocks. Despite this, detection methods for B. ovis infestation are limited to visual inspection and ELISA. A colourimetric loop-mediated isothermal amplification (LAMP) method was developed and evaluated for the detection of B. ovis DNA. Diagnostic sensitivity and specificity of LAMP were compared with those of visual inspection and PCR and validated using field samples collected from 22 farms. Two different DNA extraction methods using a commercial kit and a boiling method were also compared. The highest sensitivity and specificity were observed when PCR was used and DNA was extracted using a commercial kit. Compared with PCR, the LAMP assay demonstrated a sensitivity and specificity of 90% and 92% when DNA was extracted by a commercial kit and 100% and 75% when DNA was extracted by the boiling method, respectively. The LAMP test developed in this study could potentially serve as a point-of-care diagnostic tool for monitoring of sheep flocks as well as surveillance of B. ovis populations.

Revisiting cyst burden and risk factors for hepatic hydatid disease (Echinococcus granulosus sensu stricto) in Australian beef cattle.

The characteristics and risk factors associated with hepatic Echinococcus granulosus sensu stricto infection (hydatid disease) were investigated in beef cattle slaughtered at an abattoir in eastern Australia. Sampled cattle were sourced from all eastern states, predominantly from regions associated with the Great Dividing Range. Livers and corresponding demographic data were collected from 601 carcasses. Livers were examined for the number, size, viability, and fertility of hydatid cysts. Mixed effects logistic regression was used to evaluate associations of sex, feed-type (grass- or grain-fed), and dentition (age) on hydatid disease. Hydatid cysts were detected in all dentition groups. The most commonly sampled dentition group was zero-tooth cattle (less than 18 months). Twenty-nine percent of infected livers had only one cyst, and 48% of infected livers contained viable cysts. Thirty-seven percent of infected livers had cysts that were 3-10 mm in diameter. The size and number of cysts were positively correlated with age of the animal. Regression analysis showed that the odds of hydatid disease were highest in eight-tooth cattle (>42 months; OR 26.9; 95% CI 11.8-61.6; reference level [ref] zero-tooth). Being grass-fed was also significantly associated with the presence of hydatid disease (total effect; OR 3.0; 95% CI 1.7-5.5; ref grain-fed). Although there was no evidence of a total effect of sex across the study population, males of a given dentition group and feed-type (grass- or grain-fed) were more likely to be infected than respective females. Despite changes in Australian agriculture in the last 30 years, the burden (number, size, and viability of cysts) of hydatid disease in individual infected animals remains similar to previous Australian studies.

Impacts of naturally acquired protozoa and strongylid nematode infections on growth and faecal attributes in lambs.

On two separate sampling occasions, faecal samples were collected from lambs (2-5 months of age) grazing pasture on two separate sheep farms in southern Western Australia. Live weight, body condition score (BCS), faecal consistency score (FCS) and faecal dry matter percentage (DM%) were measured. Faecal samples were screened by PCR for Cryptosporidium (18S rRNA, actin and 60 kDa glycoprotein [gp60] loci), Giardia duodenalis (glutamate dehydrogenase [gdh] and ß-giardin) and patent strongylid nematode infections (ITS-2 nuclear ribosomal DNA for Haemonchus contortus, Teladorsagia circumcincta, Trichostrongylus spp. Chabertia ovina and Oesophagostomum spp.). Faecal worm egg counts (WECs) were performed using a modified McMaster WEC technique. The WECs were adjusted for FCS and transformed using log(10)(adjusted WEC+25) prior to statistical analyses. Cryptosporidium, Giardia and Trichostrongylus spp. detected by PCR were associated with an increased risk of non-pelleted faeces (FCS ≥ 3.0) for both flocks. Cryptosporidium-positive lambs were 2.8-11.6 times more likely to have non-pelleted faeces and Giardia-positive lambs were 2.4-14.0 times more likely to have non-pelleted faeces compared to lambs negative for each respective parasite. Lambs positive for both Cryptosporidium and Giardia were 2.9-11.8 times more likely to have non-pelleted faeces than lambs positive for only one or neither of these parasites. Mixed internal parasite infections were found to have greater impacts on FCS and BCS than single infections. A higher number of internal parasites detected per lamb was associated with lower BCS and more loose faeces. The relationship between parasite detection and live weight or growth rate were inconsistent for both flocks. Adjusted WEC was correlated with FCS and faecal DM% for one flock only, although little or no correlation was found with live weight and growth rate for both flocks. Cryptosporidium ubiquitum and Cryptosporidium parvum were the most prevalent Cryptosporidium species isolated in the two flocks. Giardia assemblage E was the most commonly isolated genotype assemblage from both flocks, while assemblage A was isolated almost as frequently as assemblage E in the one flock. One flock was a potential source of zoonotic Cryptosporidium and the other flock was a potential source of zoonotic Giardia.

Comparison of molecular and McMaster microscopy techniques to confirm the presence of naturally acquired strongylid nematode infections in sheep.

Patent strongylid nematode infections were identified using McMaster worm egg counts (WEC) and PCR assays (ITS-2 nuclear ribosomal DNA) to screen genomic DNA extracted directly from lamb faecal samples. Lambs from four different farms in southern Western Australia were sampled rectally on two separate occasions, with McMaster WECs and PCRs conducted on a total of 858 samples. Negative controls (n=96) (WEC <50 eggs per gram [epg]) and positive controls (n=96) (faecal samples spiked with a 100 µL suspension of third-stage larvae (L(3)) containing approximately equal proportions of Teladorsagia circumcincta, Trichostrongylus colubriformis, Haemonchus contortus, Oesophagostomum spp. and Chabertia ovina) were generated. All control samples amplified in accordance with positive controls. High levels of agreement (Kappa values ≥ 0.93) were identified between the two diagnostic tests. PCRs detected an additional 2.0% of samples as strongylid-positive but there was no significant difference in the number of strongylid-positive samples identified using PCR or McMaster WEC.