Fasciola hepatica products can alter the response of bovine immune cells to Mycobacterium avium subsp. paratuberculosis.

BACKGROUND: Fasciola hepatica causes economically important disease in livestock worldwide. The relevance of this parasitic infection extends beyond its direct consequences due to its immunoregulatory properties. OBJECTIVES: Given the importance of the T helper 1 (Th1) immune response in controlling infections with Mycobacterium avium subspecies paratuberculosis (MAP) in cattle, we aimed to establish the immunological consequences that co-infection with F. hepatica might have on the course of Johne's disease (JD). METHODS: This study compared the in vitro response of bovine immune cells to infection with MAP or exposure to MAP antigens following F. hepatica infection or stimulation with F. hepatica products. RESULTS: We found a decreased proliferation of peripheral blood mononuclear cells (PBMCs) after infection with F. hepatica. This reduction was inversely correlated with fluke burden. Pre-stimulation with F. hepatica molecules produced a significant reduction of ileocaecal lymph node leucocyte proliferation in response to MAP antigens. Additionally,F. hepatica products reduced expression of the CD14 receptor by macrophages and increased levels of apoptosis and bacterial (MAP) uptake. CONCLUSIONS: Overall, F. hepatica infection had little impact on the in vitro response of immune cells to MAP, whereas in vitro co-stimulation with F. hepatica molecules had a measurable effect. Whether this is likely to affect JD progression during in vivo chronic conditions remains unclear.

Cows with paratuberculosis (Johne's disease) alter their lying behavior around peak lactation.

Paratuberculosis or Johne's disease (JD) is a fatal chronic enteritis that causes detrimental effects on production and health and significantly reduces the welfare of cattle. Control of JD is highly desirable, but single milk ELISA testing may not be sensitive enough to identify all affected animals, particularly in the early stages of the disease. The objective of this study was to compare the activity of JD-positive (JD5) to JD-negative (JD0) cows from calving until wk 20 of lactation. The study was conducted at Harper Adams University, United Kingdom, using 42 multiparous [3.1 ± 0.22 (mean ± standard error of the mean); range: 2-7 lactations] Holstein Friesian cows, fitted with an IceQube accelerometer (IceRobotics Ltd., Edinburgh, UK) on the back left leg. The sensors recorded data on lying and standing time, steps, and motion index with a granularity of 15 min. In addition, start and stop times for lying bouts, and exact lying bout durations were recorded, which permits calculation of the number of lying bouts. Every 3 mo the cows were milk sampled and subsequently tested for JD using an ELISA. Cows in the infection group JD0 were classed as JD negative and cows in the infection group JD5 were classed as JD positive. Johne's-positive cows [JD5; n = 21 (repeat ELISA positive)] were matched to negative cows [JD0; n = 21 (repeat ELISA negative)] based on lactation number and age. Around peak lactation we found differences in lying behavior. The JD5 cows spend less time lying/d during wk 7 to 11 of lactation. The largest difference observed was around wk 8 of lactation, with JD5 cows spending, on average, 2 h/d less time lying down than JD0 cows (9.3 ± 0.33 vs. 11.3 ± 0.61 h/d, respectively). The JD5 cows also had fewer lying bouts per day from wk 7 to 15 of lactation (excluding wk 13), and during wk 11 and 12 average lying bout duration was longer for JD5 cows compared with JD0 cows. No differences were observed in steps per day, milk yield, BCS, and mobility score between JD5 and JD0 cows from calving to wk 20 of lactation. As far as we are aware, this is the first study to show changes in activity of JD-positive cows. The results show that activity data from leg-mounted accelerometers has the potential to help identify JD-positive cows, although more research is required.

Recovery of Mycobacterium avium subsp. paratuberculosis from nematode larvae cultured from the faeces of sheep with Johne's disease.

A study was conducted to determine whether trichostrongylid nematode larvae become contaminated with Mycobacterium avium subsp. paratuberculosis when they develop in the faeces of sheep with Johne's disease. Nematode larvae were hatched from ova in the faecal samples of affected sheep. Larval sheaths were removed and these as well as exsheathed larvae were subjected to radiometric culture for M. paratuberculosis. The organism was recovered from washing water used to prepare the larvae, third stage larvae and larval sheaths, but not from exsheathed larvae. The recovery of M. paratuberculosis from larvae was associated with the severity of the histological lesions in affected sheep and with the results of culture of the organism from intestinal tissues and faeces. Nematode parasites of sheep might be able to act as mechanical vectors for M. paratuberculosis as the organism associates with infective third stage larvae when these develop in the faeces of sheep with Johne's disease.

Earthworms (Oligochaeta, Lumbricidae) and mycobacteria.

The objective of the study was to define the role of earthworms in the survival of mycobacteria in animal populations. In 13 sampling sites mycobacteria were detected in 53 (5.5%) samples of faeces and parenchymatous tissues from animals, in 25 (7.3%) environmental and in nine (8.2%) earthworm samples. In cattle and goat farms affected by Mycobacterium avium subsp. paratuberculosis (M. paratuberculosis) of IS900 restriction fragment length polymorphism (RFLP) type B-C1 was isolated from 37 (4.6%) faecal samples, three (1.4%) environmental and one (3.1%) earthworm sample. Investigations of aviaries affected by avian tuberculosis detected M. avium of genotype IS901+ and IS1245+ in six (7.9%) bird's faecal and in four (4.4%) environmental samples. M. avium (genotype IS901- and IS1245+) was detected in four (4.4%) and M. abscessus in one (1.1%) environmental sample. M. avium of genotype IS901- and IS1245+ and M. gastri were isolated from three (6.4%) earthworm samples. In pig farm with mycobacteriosis M. avium of genotype IS901- and IS1245+ was detected in five (20.0%) faecal samples from pigs and in four (12.9%) environmental samples. M. scrofulaceum was isolated in one (4.6%) sample of Lumbricus rubellus. In laboratory experiments identical RFLP types of M. paratuberculosis were isolated from bodies and faeces of earthworms 1-2 days after the last contact with the faeces contaminated with the same RFLP type of M. paratuberculosis. The results suggest that earthworms may become vectors of mycobacteria.

Preliminary observations on ovine paratuberculosis (Johne's disease) in Zambia.

In an imported flock of sheep from South Africa, an ewe became partially anorexic and gradually losing weight and conditions. The paratuberculosis (Johne's disease) was confirmed on clinical, faecal and histopathological examination. Cultural examination remained doubtful. Serological investigation of other sheep in the flock and at other farm reacted to antibodies of Mycobacterium paratuberculosis on complement fixation test. The study suggests that the disease is actively spreading. This is the first report of ovine paratuberculosis in the Republic of Zambia.