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PubMed1994

Haematological and lymphocyte subset analyses in sheep inoculated with bovine immunodeficiency-like virus.

Bovine immunodeficiency-like virus (BIV) was passaged in vivo by intraperitoneal transfusion of ovine whole blood. Prior to transfusion, the recipient sheep were given sodium thioglycolate intraperitoneally to induce mild non-suppurative inflammation. The anti-BIV antibody response, haematology, and peripheral blood lymphocyte subsets (B, gamma delta, CD2+, CD4+ and CD8+) of recipient sheep were assessed for one year following transfusion. Passaging was successful since serum anti-BIV antibody responses were detected in 5 of the 6 recipient sheep; 1 of the 5 remained seropositive throughout the study. Lentivirus was not isolated from the recipient sheep, but provirus was detected by the polymerase chain reaction in DNA from peripheral blood leukocytes in 3 of the 5 sheep that seroconverted. In the BIV-inoculated sheep, neutrophils and eosinophils were significantly increased (p < or = 0.05) at 3 months and between 6 and 8 months postinoculation, respectively. B, CD2+ and CD4+ cells and the CD4+/CD8+ ratios were significantly increased (p < or = 0.05) 2 months postinoculation. Mild, transient haematological changes occurred in BIV-exposed sheep, but illness was not detected in the year.

Animals↗
PubMed2003

The PrP genotype of sheep of the improved Valachian breed.

In a worldwide majority of sheep breeds an excessive susceptibility to scrapie associated with the PrP gene alleles coding for valine (V; at the 136 codon) and glutamine (Q; at the 171 codon) (e.g., VRQ/VRQ, VRQ/ARQ, or ARQ/ARQ) was demonstrated. Particularly the PrPVRQ allele is closely associated with the high-risk development of the disease; the PrPARQ allele can also fulfill this function but under certain limited conditions. Polymorphism in the PrP gene sequences (conclusively related to the increased susceptibility of sheep to scrapie) of improved Valachian sheep from two Slovak regions, Orava and Spis, was determined. Examination of 735 sheep showed that ARR/ARQ was the most frequent genotype (45.2%). High-risk genotypes were determined in 32.4% of sheep (ARQ/ARQ 19.3, ARR/VRQ 9.0, ARR/VRQ 3.5, VRQ/VRQ 0.3, ARR/VRR 0.3). Low-risk genotypes were found in 67.7% of sheep (ARR/ARQ 45.2, ARR/ARR 10.9, ARR/AHQ 5.7, ARQ/ARQ 4.9, AHQ/AHQ 0.7, ARR/AHR 0.3). Despite the geographically distant flocks of improved Valachian sheep investigated no difference in the occurrence of individual PrP genotypes was observed.

Alleles↗
PubMed1999

Changes in peripheral blood lymphocyte subpopulations and parasite-specific antibody responses in Trypanosoma evansi infection of sheep.

This paper reports on changes in the lymphocyte composition of the peripheral blood in sheep infected with Trypanosoma evansi. In addition, parasite-specific IgG1 and IgM antibody responses were monitored using a double-sandwich enzyme-linked immunosorbent assay (ELISA) technique. Eight sheep were infected with 2 x 10(6) T. evansi TREU 2143. The infection was characterised by chronicity and ended in self-cure in two of the sheep. These two sheep were designated group A, whereas the other six sheep, which remained parasitaemic until treated, were designated group B. Analysis of the peripheral blood lymphocytes (PBLs) by indirect immunofluorescence staining and flow cytometry revealed significant alterations in the numbers of T- and B-cell subsets detected in all infected sheep. In group A, whereas the numbers of CD8+ cells decreased, CD4+ cells showed marginal decreases, remaining at or above pre-infection figures and resulting in increase in the CD4:CD8 ratio. In group B, CD8+ cells showed few marginal decreases, being at or above pre-infection figures most of the time, whereas CD4+ cells decreased significantly from day 26 post infection (p.i.) such that the CD4:CD8 ratio decreased. Infection also resulted in significant increases (P < 0.001) as of day 26 p.i. in circulating B-cells in group B as shown by the numbers of sIg+, CD45R+, CD1+ and major histocompatibility complex (MHC) II+ cells. The increases, however, were moderate and biphasic in group A. T. evansi-specific IgM and IgG1 antibody isotypes were detected in all infected sheep, but their levels were significantly higher in group A than in group B (IgM P < 0.05; IgGI P < 0.01). In addition, although an initially higher level of IgM response was subsequently replaced by a higher level of IgG1 response in group A, this was never the case in group B until after drug treatment.

Animals↗
PubMed1986

The macroscopic appearance and associated histological changes in the enamel organ of hypoplastic lesions of sheep incisor teeth resulting from induced parasitism.

Twenty-one penned female sheep were infected with a high dose of nematodes (200,000 Trichostrongylus vitrinus and 25,000 Ostertagia circumcincta) during first incisor development when aged 7-8 months. Three sheep were infected with 200,000 T. vitrinus only; 10 sheep were untreated. Anorexia, lassitude and severe diarrhoea were seen in 14 of the infected sheep after 21-26 days. Anthelmintic was given to sheep showing undue distress to end the infection and to all remaining sheep on day 33. Animals were killed at 3 stages: during the infection, at intervals during later tooth development, and at the time of eruption of the incisor teeth, 7-8 months after the parasites were given. Hypoplasia of the labial enamel of 15 out of 19 teeth from sheep killed after recovery from the infection was classified according to the extent and depth as pits, grooves or larger areas of missing enamel with ledge-formation cervically. The amount of missing enamel related to the severity of the systemic disturbance which affected the secretory ameloblasts. During the period of active infection, some secretory ameloblasts showed vacuolization or were shorter than in controls; some cells were no longer adjacent to the organic matrix; some continued to function but abnormally and later became separated from the retained organic matrix by connective tissue. Cervically-placed ledges resulted either from the recovery and resumption of activity of some ameloblasts or from differentiation of new secretory cells after the infection ended.

Ameloblasts↗
PubMed1992

Tannic acid intoxication in sheep and mice.

Acute tannic acid intoxication was studied in mice and sheep. In mice, following oral administration of 2.0 to 4.6 g of tannic acid kg-1 bodyweight, periacinar coagulative and haemorrhagic necrosis occurred in the liver. In sheep, following oral (8 g kg-1 bodyweight) administration of tannic acid, liver necrosis was not observed either histologically or detected biochemically, although transmission electron microscopy showed focal hepatocellular necrosis, steatosis and acicular crystal cleft formation. In sheep given tannic acid intraperitoneally (0.1 g kg-1 bodyweight), liver necrosis occurred and plasma sodium and glucose levels significantly (P < 0.05) decreased while packed cell volume and plasma aspartate aminotransferase, alkaline phosphatase, creatinine and bilirubin significantly (P < 0.01) rose. The results for blood-gas and acid-base determinations, blood haemoglobin and oxygenation showed significant increases in arterial blood methaemoglobin concentration (P < 0.05) and decreases in blood pH (P < 0.01) and oxyhaemoglobin concentration (P < 0.05) in sheep by 32 hours after oral dosing with 8 g of tannic acid kg-1 bodyweight. In sheep given tannic acid intraperitoneally, methaemoglobinaemia was not detected, but metabolic acidosis with a compensatory respiratory alkalosis occurred. Thus, it would appear that although tannic acid is hepatotoxic when given orally to mice or intraperitoneally to sheep, it does not produce renal or significant hepatic injury in sheep when given orally, but rather causes metabolic acidosis and methaemoglobinaemia.

Administration, Oral↗
PubMed1995

Effect of flunixin meglumine on the thresholds to mechanical stimulation in healthy and lame sheep.

The antinociceptive effect of flunixin meglumine was assessed in healthy and lame sheep by using a noxious mechanical stimulus. Sheep suffering from the chronically painful condition, footrot, have previously been shown to have lower thresholds to noxious mechanical stimuli than healthy animals. In the present study, 22 sheep suffering from footrot did not have a lower mean mechanical threshold than 25 matched healthy animals, but it was significantly greater than that recorded from eight experimental sheep (5.0 [2.5], 4.9 [2.1] and 3.0 [1.0] Newtons, respectively). Doses of 1.0 or 2.0 mg kg-1 of flunixin meglumine had no effect on the thresholds to noxious mechanical stimulation in either experimental sheep tested over six hours, or in lame sheep tested over a period of 30 minutes. The repeated administration of flunixin to sheep suffering from footrot over a period of three days reduced their thresholds to noxious mechanical stimulation.

Animals↗
PubMed1986

Heterologous resistance to Fasciola hepatica conferred upon rats by passive transfer of serum from different breeds of sheep.

Two experiments compared the protection against oral challenge with 20 metacercariae of Fasciola hepatica conferred on rats by intraperitoneal injection of serum from three breeds of sheep infected with F. hepatica (Barbados Blackbelly, St. Croix, Florida Native). Experiment 1 used serum from sheep 5-6 months of age following two infections of 250 metacercariae each, while Experiment 2 utilized serum collected from the same sheep at 10-11 months of age following either a primary (first exposure) or challenge (after two previous exposures of 250 metacercariae each) infection with 500 metacercariae. Similar numbers of flukes were recovered from rats given either immune or nonimmune (control) serum from each breed of sheep in Experiment 1. In Experiment 2, rats given serum from infected St. Croix sheep had significantly fewer flukes than rats given either control or immune serum from Barbados Blackbelly or Florida Native sheep. There was no significant correlation of fluke counts between individual serum donors (sheep) and serum recipients (rats).

Analysis of Variance↗
PubMed1988

Antibody development and cellular immune responses in sheep immunized and challenged with Sarcocystis tenella sporocysts.

Four specific-pathogen-free (SPF) sheep were experimentally infected with 10(3) or 10(4) Sarcocystis tenella (syn. S. ovicanis) sporocysts and another two sheep served as uninfected controls. All sheep were challenged 49 days later by infection with 2.5 X 10(5) sporocysts and their humoral and cellular responses to infection and challenge were assessed weekly by enzyme immunoassays and lymphocyte transformation assays. The control sheep died from acute sarcocystosis 29-30 days after challenge, whereas the immunized sheep survived and were protected against acute disease. Specific IgM and IgG antibodies were detected in the immunized sheep from 28 days after infection onwards. Lymphocytes collected before and after challenge did not exhibit any significant differences in their responses to stimulation with S. tenella cystozoite or sporozoite antigens. Furthermore, lymphocytes collected before challenge did not differ from the controls in their responses to stimulation with the mitogens lipopolysaccharide or phytohaemagglutinin. However, lymphocytes collected after challenge did exhibit increased blastogenic responses to stimulation with both mitogens from 21-28 days after challenge onwards. The infected sheep were necropsied 46 days after challenge, and histological and ultrastructural studies revealed numerous infiltrates of lymphocytes, histiocytes and plasma cells in the skeletal muscles, sometimes in association with degenerating parasitic cysts and macrophage myophagia. Parasites were not completely eliminated nor prevented from further establishment, therefore the protective immunity was not sterile but rather a state of premunition.

Animals↗
PubMed1995

Ovine toxoplasmosis: seroconversion during pregnancy and lamb birth rate in Uruguayan sheep flocks.

Specific anti-Toxoplasma gondii antibodies were analyzed by latex agglutination during the 5 months of pregnancy in the serum of sheep from two flocks in the Uruguayan north-west: one flock (79 sheep) kept under an intensive management system and the other (494 sheep) kept under an extensive management system. Titers obtained using the latex test correlated with those obtained by indirect immunofluorescence. Pregnancy was confirmed by laparoscopy in all sheep from the smaller flock and by determination of serum progesterone levels in the seroconverted sheep from the larger flock. The percentage of sheep originally exhibiting significant serum levels of anti-T. gondii antibodies (13.9% in the smaller flock and 28.5% in the larger one) as well as the observed levels of seroconversion (22.8% and 7.7%, respectively), indicated a high prevalence of this infection in the north-west of Uruguay. In addition, birth rates of seroconverted sheep in the larger flock were significantly different from those of non-seroconverted animals. These results, although preliminary, suggest that Toxoplasma infection would produce considerable economic losses in extensive ovine production in Uruguay.

Animal Husbandry↗
PubMed1994

Controlled release insecticide devices for protection of sheep against head strike caused by Lucilia cuprina.

The effectiveness of polymer matrix tags containing (w/w) 8.5% cypermethrin, 7.5% flucythrinate, 13.7% tetrachlorvinphos or 20.0% diazinon in protecting sheep against head strike by the sheep blowfly (Lucilia cuprina Wiedemann) was investigated in larval implant, fly cage and field studies. Tags impregnated with cypermethrin reduced the total number of egg masses deposited on the heads of sheep in fly cage studies over a 6 week period by 73.3% compared with no treatment. Tags impregnated with flucythrinate reduced the number of egg masses by 25.3% over 21 weeks but there were no significant differences (P < 0.05) between treated and untreated sheep at individual exposures. Egg masses were found on the majority of tagged sheep and no protection was provided against implants with first instar L. cuprina larvae by either cypermethrin or flucythrinate tags. Tags impregnated with diazinon gave longer protection than treatment with a liquid formulation containing 400 ppm diazinon in larval implant, fly cage and field studies. Over a 12 week period in field studies, 6.6% of rams treated with diazinon tags became struck compared with 30% treated by diazinon jetting, 35.7% treated with plastic tags not impregnated with insecticide and 24.2% of untreated rams. When the rams were exposed to high populations of L. cuprina in an exposure house from 13 to 18 weeks after treatment, 3.3% of rams treated with diazinon tags, 57.1% treated by diazinon jetting, 43.8% treated with plastic tags and 23.5% of untreated rams became struck. Most strikes in the diazinon tagged sheep occurred at sites which were not contacted by the tags. Tags impregnated with tetrachlorvinphos reduced the number of strikes in comparison with no treatment in larval implant and fly cage studies but the results were inconsistent and not as good as those from diazinon tags. It is concluded that well designed controlled release devices that reliably contact the wool on the heads of sheep at sites of flystrike risk and which are able to withstand damage from rams fighting may be able to give prolonged protection against head strike.

Administration, Topical↗
PubMed1996

Prevalence of dicrocoeliosis in sheep and goats in Himachal Pradesh, India.

A survey incorporating field and abattoir studies was carried out on the prevalence of Dicrocoelium dendriticum in sheep and goats in the Kangra valley of Himachal Pradesh (India). Coprological studies on these migratory animals revealed that 8.1% of sheep and 4.1% of goats were positive for dicrocoeliosis, with a mean number of eggs per gram of faeces (EPG) of 702.1 for sheep and 566.7 for goats. The necropsy liver examination of slaughtered animals revealed that 24.1% of sheep and 12.3% of goats were infected with D. dendriticum and they had mean fluke burdens of 247.2 (sheep) and 298.1 (goats). No significant differences in fluke burden, liver lesion score and EPG count were observed between sheep and goats. The seasonal distribution of dicrocoeliosis indicated a higher percentage of infection in autumn and winter as compared with spring and summer. The potential role of migratory sheep and goats in the epizootiology of dicrocoeliosis is discussed.

Animals↗
PubMed1995

An ivermectin tablet for sheep: efficacy against gastro-intestinal nematodes and a bioavailability comparison with a liquid ivermectin formulation.

An ivermectin tablet for oral administration to sheep was developed for use in countries where it is customary to treat sheep with anthelmintic tablets. Tablets require no special administration equipment, and offer convenience for storage and transport. The ivermectin tablet, which delivers 10 mg of ivermectin (200 micrograms kg-1 in a 50 kg sheep), had similar bioavailability to a liquid formulation of ivermectin (IVOMEC Liquid for Sheep) as determined by peak plasma ivermectin concentrations and area under the concentration curve in plasma (P > 0.10). In dose confirmation trials in which nematode infections were induced in helminth-naive sheep, animals treated with the ivermectin tablet had significantly fewer adult and fourth-stage larval nematodes than untreated control sheep (P < 0.01) with efficacies > 99% against all nematode species tested. In six field trials evaluating the efficacy of the ivermectin tablet in 240 Merino sheep, the reductions in faecal nematode egg counts ranged between 98 and 100%, as determined by comparison of pre- and post-treatment counts for the ivermectin-treated group.

Administration, Oral↗
PubMed1996

The pathophysiology and development of immunity during long-term subclinical infection with Trichostrongylus colubriformis of sheep receiving different nutritional treatments.

The objective of this study was to investigate the relationship between protein nutrition, the pathophysiology, and acquisition and expression of immunity in long-term subclinical intestinal parasitism in sheep. Growing sheep were either uninfected controls or parasitised for 27 weeks with a daily dose of 2500 larvae of Trichostrongylus colubriformis, whilst they were given access to: (1) a low protein food, (2) a high protein food, or (3) a choice between the two foods, where they were allowed to select their diet. Blood samples were taken weekly for determination of serum albumin, total protein, Ca, P, urea and fructosamine concentrations. At the end of the study all sheep received a single (secondary) challenge infection (30,000 T. colubriformis L3) after treatment with anthelmintic to assess their immune status. The concentrations of sheep-mast cell proteinases (SMCP) in intestinal tissue, the number of circulating eosinophils and the total worm numbers recovered from the intestinal tract were used to investigate the effects of previous nutrition on the acquisition and expression of immunity. From the biochemical variables measured over 27 weeks, only serum fructosamine was affected by the interaction between feeding treatment and parasitism: fructosamine concentrations declined only in the parasitised animals on the low protein food during Weeks 6-15 of infection. This casts doubt on the usefulness of plasma fructosamine levels as an indicator of gastrointestinal parasitism, due to its being influenced by the nutritional environment. Total protein, albumin, calcium and phosphorus concentrations in the serum were affected by parasitism, but independently of feeding treatment. During the period of secondary challenge eosinophil numbers and SMCP concentrations were higher in the parasitised animals, reflecting the animals immune responsiveness. The numbers of worms recovered from the intestine of previously parasitised sheep were low; all three indicators of the development of acquired immunity were unaffected by previous nutritional treatment of the sheep. The results do not support the view that the pathophysiology of long term subclinical intestinal parasitism and the expression of acquired immunity induced by a trickle infection could be affected by the feeding treatment of the sheep (protein nutrition).

Animal Nutritional Physiological Phenomena↗
PubMed1984

Maedi-visna control in sheep II. Half-yearly serological testing with culling of positive ewes and progeny.

In 1979 a field trial was started to study the feasibility of maedi-visna control in sheep by half-yearly serological testing (by ELISA) with culling of sero-positive ewes and their progeny. In 13 commercial flocks, with a mean initial incidence of serological reactors of 17%, the sero-positive ewes and all their progeny, those of preceding years included, were culled after each half-yearly test. The percentage of sero-positive sheep decreased gradually and at the end of the second year, at the 5th test, all flocks were sero-negative. Also the 6th and 7th test did not yield sero-positive sheep. At the 8th test, however, 3 sero-positive ewes were detected in one of the flocks. A definite conclusion as to the source of infection could not be drawn. The following flock test was negative. In 2 other commercial flocks, which had a mean initial incidence of sero-positive sheep of 53%, those sero-positive and only their suckling lambs were culled. Here too, a gradual decrease in the incidence of sero-positive sheep was observed at the 2nd and 3rd test, but at the 4th test a sharp increase occurred. The programme was continued and a decrease followed until 0% was reached at the 7th test (end of third year). Age analysis of the sero-positive sheep which caused this peak revealed that the majority had been born before the start of the trial. This suggests that a 'second wave' of sero-positive sheep may be prevented and a quicker result obtained if progeny of preceding years are culled as well.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Alterations in lymphocyte subpopulations in peripheral blood of sheep persistently infected with border disease virus.

Fourteen sheep persistently infected with border disease virus were investigated to examine the effects of persistent viraemia on lymphocyte subpopulations in peripheral blood and their responses to the mitogen phytohaemagglutinin (PHA) in vitro. Persistently infected sheep had significantly more CD8+ (cytotoxic-suppressor) T-lymphocytes than uninfected sheep of the same age (P less than 0.001). The total number of CD4+ (helper) T-lymphocytes were not significantly different but there were more T-lymphocytes (CD5+) which were CD4- and CD8- in normal sheep than persistently infected sheep (P less than 0.001). Peripheral lymphocytes obtained from persistently infected sheep showed significantly reduced blastogenesis induced by PHA than those obtained from normal sheep (P less than 0.001).

Animals↗
PubMed1994

Antibody response to Brucella melitensis outer membrane antigens in naturally infected and Rev1 vaccinated sheep.

Sera from Brucella infected and B. melitensis Rev1 vaccinated sheep were analysed by immunoblotting using the cell envelope fraction (CEF) of B. melitensis B115. The CEF of B. melitensis B115 was analysed using a bank of monoclonal antibodies. The fraction consisted mainly of S-LPS like molecules, R-LPS and outer membrane proteins (OMPs) of molecular masses of 10, 16.5, 19, 25-27, 31-34, 36-38, 73 and 89 kDa. Immunoblot analysis indicates that the antibody response in infected sheep was mainly directed against the major OMPs of 25-27, 31-34, 36-38 kDa, against 55 to 62, 70-73 and 89 to 94 kDa proteins associated with the CEF and, against S-LPS like molecules. Some infected sheep reacted with antigens of molecular mass lower than 20 kDa. Sera from vaccinated sheep reacted only with OMPs of 36-38, 60, 70-73 and 89 kDa. The major 25-27 and 31-34 kDa OMPs and proteins below 20 kDa were only detected by the sera of infected sheep. These differences may be due to the persistence of the field infection also reflected by the fact that antibody response against O-polysaccharide (O-PS), as measured by enzyme-linked immunosorbent assay (ELISA), was more intense in infected sheep than in vaccinated ones. These results also indicate that these OMPs could be useful to differentiate B. melitensis infection from B. melitensis Rev.1 vaccination in sheep.

Animals↗
PubMed2006

Prevalences of gastrointestinal parasites in sheep and parasite-control practices in NW Spain.

A coprological survey to know the presence of gastro-intestinal nematode parasites infecting sheep was done in Galicia (NW Spain), an area with Atlantic climate where sheep production is replacing cattle due to the Agricultural Community Politics of the European Union. From September 2001 to November 2002, 1710 faecal samples were randomly collected from 49 sheep farms and examined by using the flotation technique to determine the prevalence of gastro-intestinal nematode parasites. The sheep-level prevalence was 100%, and the genera identified were Chabertia, Cooperia, Haemonchus, Nematodirus, Oesophagostomum, Teladorsagia, Trichostrongylus and Trichuris spp. A questionnaire was distributed to the farmers (at the same time as sampling) about parasite-control practices during the year before sampling (2000). Ninety percent (95% CI 81%, 98%) of the farmers said they used antiparasitic drugs occasionally, but none of them asked for a coprological analysis prior to the treatment and the efficacy of the drugs was never evaluated. A higher median EPG was observed in the treated sheep (163) than in the untreated ones (26). Chemotherapy was the only parasite-control practice. Flocks that treated according to the farmer's previous experience had higher median EPG (236) than other flocks (185 following the prescription of their veterinary clinician and 232 based on the commercial agent's counsel). Typically, one benzimidazole-treatment per year was applied in autumn and non-veterinary counsel was used. Sheep treated with imidotiazoles had lower EPG (144) than other drugs (164 for the benzimidazoles and 166 for the macrocyclic lactones). We found a higher median EPG in the sheep receiving two treatments/year (175) than in those treated only once per year (156). These results suggest lack of knowledge about worm-control strategies and anthelmintic use or unwillingness to apply such knowledge.

Animals↗
PubMed2005

Horizontal Maedi-Visna virus (MVV) infection in adult dairy-sheep raised under varying MVV-infection pressures investigated by ELISA and PCR.

A three year long experimental study was carried out to investigate horizontal MVV-infection by PCR and ELISA, in 191 one year-old latxa dairy-sheep raised in two separate groups under low and high MVV-infection pressure, respectively. Sheep originated from a previous MVV-transmission study in lambs and seroprevalence among one year-old sheep in both groups was 15% approximately. The high infection-pressure group (H-group) consisted of 147 replacement ewes that joined a milk-producing, housed dairy-flock with 42-66% MVV-seroprevalence and the low infection-pressure group (L-group) were castrated males raised in a separate shed. In contrast to results obtained when infection was investigated in lambs, the overall degree of agreement between ELISA and PCR results was very good and there was some indication that it increased further as sheep became older. MVV-prevalence did not change in the L-group and increased to 57% in three year-old sheep in the H-group (p<0.001). Random effects logistic regression confirmed seroconversion was significantly higher in the H-group compared to the L-group and was highest during the year after the sheep were introduced in the dairy flock and did not increase with age as in previous studies using less sensitive antibody assays. The evidence that horizontal transmission can be very low in spite of prolonged close contact between infected and non-infected sheep is valuable for MVV-control purposes. Furthermore it highlights the need to investigate virus excretion dynamics in infected animals and animal to animal transmission to improve our overall understanding of horizontal MVV transmission in MVV endemic populations.

Aging↗