The effect of gilt flow management during acclimation on Mycoplasma hyopneumoniae detection.

The objective of this study was to characterize the Mycoplasma hyopneumoniae (M. hyopneumoniae) detection and seroconversion patterns in recently acclimated gilts to be introduced to endemically infected farms using different types of replacement management. Three gilt developing units (GDUs) belonging to sow farms were included in this investigation: two farms managed gilts in continuous flow, and one farm managed gilts all-in/all-out. Two replicates of 35 gilts each were selected per GDU and sampled approximately every 60 days for a total of four or five samplings, per replicate and per GDU. Detection of M. hyopneumoniae was evaluated by PCR, while antibodies were measured using a commercial ELISA assay. Also, M. hyopneumoniae genetic variability was evaluated using Multiple-Locus Variable number tandem repeat Analysis. Detection of M. hyopneumoniae was similar across GDUs. Although a significant proportion of gilts was detected positive for M. hyopneumoniae after acclimation, an average of 30.3 % of gilts was negative at any point during the study. Detection of M. hyopneumoniae antibodies was similar among GDUs regardless of flow type or vaccination protocol. The genetic variability analysis revealed a limited number of M. hyopneumoniae types within each GDU. Results of this study showed a similar pattern of M. hyopneumoniae detection by PCR and seroconversion by ELISA among GDUs, regardless of the type of flow management strategies applied to gilts.

Interventions to reduce porcine epidemic diarrhea virus prevalence in feed in a Chinese swine production system: A case study.

Research has shown that feed and feed ingredients can be one of the potential routes of transmitting viral pathogens into swine farms. In this short communication, we report two cases of Porcine Epidemic Diarrhea (PED) in two sow farms located in eastern China. Immediately after the outbreaks, extensive sampling and testing for genetic materials of PEDV was carried out on farms, and at the feed mill, in an effort to identify possible sources of infection based on field observations of local area viral spread and interventions already implemented to lower risk of this spread. Samples collected from personnel or supplies entering the farms were inspected and proved as low risk factors. In contrast, feed and feed ingredient samples collected at the on-farm feed bins, and at the feed mill, tested positive for PEDV RNA. Based on these data, multiple interventions to lower viral spread via feed were implemented including (1) simplification of diet formulation excluding high-risk ingredients, (2) extension of thermal treatment during pellet conditioning and (3) maximising feed quarantine on farm up to 7 days from feed delivery to consumption. Collectively, these interventions appeared to have a positive effect as the prevalence of PED-related disease and the number of PEDV-positive feed or feed ingredient samples decreased considerably following implementation.

Detection of the Emerging Picornavirus Senecavirus A in Pigs, Mice, and Houseflies.

Senecavirus A (SVA) is an emerging picornavirus that has been recently associated with an increased number of outbreaks of vesicular disease and neonatal mortality in swine. Many aspects of SVA infection biology and epidemiology remain unknown. Here, we present a diagnostic investigation conducted in swine herds affected by vesicular disease and increased neonatal mortality. Clinical and environmental samples were collected from affected and unaffected herds and were screened for the presence of SVA by real-time reverse transcriptase PCR and virus isolation. Notably, SVA was detected and isolated from vesicular lesions and tissues of affected pigs, environmental samples, mouse feces, and mouse small intestine. SVA nucleic acid was also detected in houseflies collected from affected farms and from a farm with no history of vesicular disease. Detection of SVA in mice and housefly samples and recovery of viable virus from mouse feces and small intestine suggest that these pests may play a role on the epidemiology of SVA. These results provide important information that may allow the development of improved prevention and control strategies for SVA.

Detecting Aelurostrongylus abstrusus-specific IgG antibody using an immunofluorescence assay.

Diagnosis of feline lungworm, Aelurostrongylus abstrusus, is typically achieved by identifying larvae in feces following concentration through flotation or using the Baermann technique. This work presents observations on the usefulness of an indirect immunofluorescence antibody assay for detection of antibodies to this parasite in the sera of infected cats. Using first-stage larvae of A abstrusus and sera from both experimentally and naturally infected cats, it was determined that the test was fairly sensitive and did not cross-react with serum from an Ancylostoma braziliense (hookworm)-infected cat.

Prevalence of Ancylostoma braziliense in cats in three northern counties of Florida, United States.

A convenience sampling of fecal specimens from 40 cats in northern Florida was examined for the presence of Ancylostoma braziliense eggs by using centrifugal sugar flotation and polymerase chain reaction (PCR)-restriction fragment length polymorphism (RFLP). Of the 40 samples, 26 (65%) contained hookworm eggs. DNA from 24 samples was successfully amplified using PCR; using RFLP, 10 samples were identified as containing DNA of A. braziliense (41.7% of the 24 samples that successfully amplified). Of these, 6 samples contained DNA of both Ancylostoma tubaeforme and A. braziliense, and 4 samples contained only DNA of A. braziliense. The remaining samples (n  =  14) contained only the DNA of A. tubaeforme, except for 1 sample that had no discernible bands after RFLP.

Obtaining an isolate of Ancylostoma braziliense from cats without the need for necropsy.

Because the eggs of Ancylostoma species of dogs and cats are difficult to readily distinguish morphologically, isolation of a certain species often requires the humane death of the source animal or holding an animal after treatment to obtain worms for specific identification or to harvest ex utero eggs. The objective of this study was to obtain an isolate of Ancylostoma braziliense from 1-time, field-collected samples of feline feces without the need for the killing of any animals. During a collection trip to Florida, fecal samples (n  =  40) were collected and identified as containing A. braziliense eggs (n  =  26) using centrifugal sugar flotation. Eggs from hookworm-positive slides were washed into tubes, DNA was extracted, and 10 samples were identified as containing A. braziliense using restriction fragment length polymorphism (RFLP) with Hinf1. Six of these samples also contained DNA of Ancylostoma tubaeforme and, thus, only 4 samples were from cats infected only with A. braziliense. Larvae cultured from two of the latter samples were used to subcutaneously inoculate a purpose-bred puppy with the intention to inhibit the growth of any potentially contaminating A. tubaeforme larvae in the culture. The infection was patent at 14 days after inoculation, and the eggs were identified as A. braziliense by RFLP and DNA sequencing. Larvae were cultured from the feces of this dog and used to infect a laboratory-reared, specific-pathogen-free cat; the eggs and larvae produced by the cat were also identified molecularly as those of A. braziliense. The larvae from this cat were used to infect other cats to maintain the isolate for further research. Both the puppy and the first cat used in this study were treated to clear their infections and have since been adopted by new owners.

Morphological differentiation of eggs of Ancylostoma caninum, Ancylostoma tubaeforme, and Ancylostoma braziliense from dogs and cats in the United States.

The establishment of cat- and dog-derived laboratory strains of Ancylostoma braziliense allowed for a morphological comparison of the eggs of A. braziliense, Ancylostoma caninum, and Ancylostoma tubaeforme. The length, width, and perimeter were determined for images of 10 eggs each of A. braziliense from the feces of a dog infected with a canine isolate and a cat infected with a feline isolate, A. caninum from dog feces, and A. tubaeforme from cat feces. The specific identity of the eggs was verified by polymerase chain reaction and restriction fragment length polymorphism by using HinfI and RsaI restriction digests followed by gel electrophoresis and sequencing. The mean (±SD) length, width, and perimeter and the length-to-width ratio (±SD) (all measurements are in micrometers) for the eggs of each species were as follows: A. braziliense eggs (combined cat and dog source), 53.03 ± 2.33, 36.37 ± 1.35, 140.43 ± 2.56, and 1.46 ± 0.11; A. caninum eggs, 63.92 ± 5.28, 39.21 ± 1.52, 161.99 ± 9.30, and 1.63 ± 0.13; and A. tubaeforme eggs, 61.44 ± 3.05, 39.14 ± 1.40, 157.98 ± 5.81, and 1.57 ± 0.08. The eggs of A. braziliense were significantly (P < 0.001) smaller than the eggs of A. caninum and A. tubaeforme in all dimensions. Thus, the eggs seem to be readily distinguishable using light microscopy, thereby aiding in species identification in fecal samples for a more comprehensive clinical picture and assessment of zoonotic risk.