Paratuberculosis vaccination specific and non-specific effects on cattle lifespan.

Records of cattle vaccination against paratuberculosis (PTB) have been analyzed to determine whether or not non-specific effect (NSE) on overall mortality similar to that observed in BCG vaccinated humans occurs in animals. The results of a previously reported slaughterhouse study on PTB prevalence were used as a reference on the age incidence of advanced patent (clinical) epidemio-pathogenic forms. In the proper vaccine study, cows in 30 cattle farms in the Basque Country, Spain were followed-up for between 1 and 13 years. Vaccinated groups were composed by 1008 (592 right-censored) animals younger than 3 months treated as calves and by 3761 (3160 right-censored) vaccinated at any older age. Controls were 339 (157 right-censored) and 4592 (2213 right-censored) age matched animals, respectively. Individual last year presence in the annual testing was considered age at culling or death. A survival analysis was carried out according age at vaccination of vaccinated versus non-vaccinated animals. PTB age incidence in the slaughterhouse study was subtracted from the difference between vaccinated and non-vaccinated animals at the same age in order to estimate PTB-specific and non-specific effects. The maximum difference was observed at the 2-3 years interval with a 33.9% mortality reduction in the calf vaccinated group. This corresponded also with the maximum NSE that was 24.5% for a PTB incidence of 9.5%. Overall, vaccination afforded to calves a 26.5% yearly mortality protection, split between 11.1% PTB-specific and 15.4% NSE. These results support a NSE on total mortality associated with PTB vaccination that appeared to persist for up to 6-7 years. This confirms for the first time in an animal field study the innate immune system memory predicted by the recently proposed trained immunity theory. Contrasting the literature, no deleterious effects of killed vaccines on females were observed. Mortality reduction would offset vaccination costs and could improve livestock systems efficiency and potentially reduce antibiotic use. Clinical trial registered with Spanish Agency for Drugs and Sanitary products (AEMPS) as 11/012/ECV.

Parenteral Vaccination with Heat-Inactivated Mycobacterium Bovis Reduces the Prevalence of Tuberculosis-Compatible Lesions in Farmed Wild Boar.

In 2012, a wild boar (Sus scrofa) tuberculosis (TB) control programme was set up in a wild boar farm by means of intramuscular (IM) vaccination with a heat-inactivated Mycobacterium bovis vaccine (IV). The goal was to assess safety and efficacy of the parenterally administered IV in a large farm setting with natural M. bovis circulation. Based on preceding results under laboratory conditions, we hypothesized that vaccinated piglets would show smaller scores of TB-compatible lesions (TBCL) than unvaccinated controls. After vaccination, no adverse reactions were detected by visual inspection or at post-mortem examination (n = 668 and 97, respectively). Post-mortem data on TBCL were available for 97 vaccinated wild boar and 182 controls. The observed TBCL prevalence was 4.1% (95% CI = 0.2-8%) and 12.1% (95% CI = 7.1-17.1%) for vaccinated and control wild boar, respectively (P < 0.05). Among those animals with TBCL, no difference in the mean lesion score was found (P > 0.05). The results show that IV administered intramuscularly to wild boar piglets is safe and protects vaccinated individuals (66% reduction in TBCL prevalence) against natural challenge in a low-prevalence setting. In a context of increasing TB prevalence in wild boar in Mediterranean habitats, vaccination achieved a progressive though slow decline in lesion prevalence since the onset of the vaccination scheme. Hence, vaccination might contribute, along with other tools, to TB control in wild boar and in pigs.

Detection of mycobacterium avium subsp. paratuberculosis in a cattle/pudu interface / Detecção de mycobacterium avium subsp. paratuberculosis em uma interface gado/pudu

Mycobacterium avium subsp. paratuberculosis (Map) is the etiological agent of paratuberculosis. In Chile, information about Map isolation from both domestic ruminant and wildlife species has been accumulating, but it has to be extended to other species. The present study focuses specifically on one wild grazing species, the pudu (Pudu puda), one of the less known South American deer considered an endangered species that shares pastures with cattle in southern Chile, where the greatest part of the country's dairy cattle population is located. Convenient samples from 3 pudus were collected from one dairy farm where Map infection had previously been confirmed in cattle. All three pudus shed the bacterium in feces and the isolates are the same type of Map as described for cattle. This study represents the first case report of Map isolation in the pudu captured from the wild. It is also the first documented association between a Map-infected dairy herd and free-ranging wildlife species, such as pudu in the Los Ríos region, Chile. Since interspecies transmission of Map and other pathogens from livestock to pudu has already been demonstrated, the results from this study suggest that this free-ranging wildlife specie, inhabiting a dairy district in southern Chile, might represent another case of spillover host.

O agente etiológico da paratuberculose é o Mycobacterium avium subsp. paratuberculosis (Map). No Chile, já foi gerada informação do isolamento do Map em ruminantes domésticos e em algumas espécies selvagens, porém essa informação deve ser expandida a outras espécies. O presente estudo está focado na espécie selvagem herbívora, o Pudu (Pudu puda), que é considerado um dos cervos menos conhecidos da América do Sul, e que está em extinção. Essa espécie compartilha as pastagens com o gado no sul do Chile, local do país onde está concentrada a maior parte do rebanho leiteiro. Foram obtidas amostras de 3 pudus de uma fazenda de gado leiteiro, onde previamente havia sido confirmada a infecção por Map em bovinos. Os três pudus eliminavam a bactéria nas fezes, e os isolados fecais foram do mesmo tipo do Map relatado para os bovinos. Este estudo representa o primeiro relato de caso de isolamento do Map em pudu em vida silvestre. Também é a primeira associação documentada entre um rebanho leiteiro infectado com Map e a infecção de uma espécie silvestre de vida livre, tal como o pudu na região de Los Ríos, no Chile. A transmissão interespécies do Map, do mesmo modo que de outros patógenos de ruminantes para o pudu, já foi demonstrada, assim os resultados deste estudo sugerem que essa espécie de vida extensiva, que habita a mesma região leiteira no sul do Chile, pode representar mais um caso de repercussão ao hospedeiro.

Goats challenged with different members of the Mycobacterium tuberculosis complex display different clinical pictures.

Tuberculosis (TB) in goats (Capra hircus) is due to infection with members of the Mycobacterium tuberculosis complex (MTC), mainly Mycobacterium bovis and Mycobacterium caprae. We report a comparative experimental infection of goats with M. bovis, M. caprae and M. tuberculosis strains. We hypothesized that goats experimentally infected with different members of the MTC would display different clinical pictures. Three groups of goats were challenged with either M. bovis SB0134 (group 1, n=5), M. caprae SB0157 (group 2, n=5) and M. tuberculosis SIT58 (group 3, n=4). The highest mean total lesion score was observed in M. bovis challenged goats (mean 15.2, range 9-19), followed by those challenged with M. caprae (10.8, 2-23). The lowest score was recorded in goats challenged with M. tuberculosis (3, 1-6). Culture results coincided with the lesion scores in yielding more positive pools (7/15) in M. bovis challenged goats. By contrast, only three pools were positive from goats challenged M. tuberculosis (3/12) and with M. caprae (3/15), respectively. Differences in the performance of the intradermal and gamma-interferon (IFN-γ) tests depending of the group were observed since all goats from group 1 were diagnosed using intradermal test and these goats reacted earlier to the IFN-γ assay in comparison to the other groups. This study confirmed that goats experimentally infected with different members of the MTC display different clinical pictures and this fact may have implications for MTC maintenance and bacterial shedding.

Coexistence of granulomatous enteric inflammation and neoplasia in an adult sheep.

A 7-year-old dairy sheep suffering from chronic loss of weight without diarrhea or anorexia was euthanized after failing to respond to any treatment (antibiotic and antiparasitic). The main findings at the necropsy of this animal were multifocal miliary nodules in several organs, mainly in the Peyer's patches of the small intestine, and a segmental thickening of the jejunal wall. Histologic examination of the samples taken at the necropsy showed a multifocal chronic granulomatous inflammation, with mineralization and caseous necrosis at the core of the larger granulomas and scarce intrahistiocytic acid-fast bacilli consistent with a disseminated digestive tuberculosis. Polymerase chain reaction and bacteriological culture from these samples confirmed Mycobacterium avium subsp avium to be the etiologic agent of this infection. Histologically, the cause of the segmental thickening of the jejunal wall was found to be a small intestine adenocarcinoma, which in some areas coexisted with the granulomatous lesion.

Immunization of adult dairy cattle with a new heat-killed vaccine is associated with longer productive life prior to cows being sent to slaughter with suspected paratuberculosis.

The objective of this study was to evaluate the efficacy of a new heat-killed Mycobacterium avium ssp. paratuberculosis (MAP) vaccine for control of premature culling in tuberculosis-free dairy cattle. Feces and gastrointestinal tissues were collected from 50 vaccinated cows and 38 nonvaccinated cows at slaughter and analyzed by bacteriological culture and histopathology. Vaccination was associated with a significant reduction of the frequency of vaccinated animals with MAP in feces and gut tissues compared with the nonvaccinated animals. In addition, the frequency of vaccinated animals with heavy bacterial load in gut tissues was 40% lower than the frequency of the nonvaccinated animals with the same MAP load. The peak age of paratuberculosis-associated culling was from 4.5 to 5 yr old (21%) in the vaccinated animals and from 3 to 4.5 yr old (60%) in the nonvaccinated animals. The vaccinated and nonvaccinated animals with suspected paratuberculosis were culled at an average age of 4.7 and 3.7 yr old, respectively. Therefore, a significant increase in the productive life of the vaccinated animals sent to slaughter with suspected paratuberculosis was observed. In addition, our analysis revealed a positive effect of the vaccine on the carcass weights of the animals with severe histopathological lesions at slaughter compared with the nonvaccinated animals. In summary, our findings suggest a therapeutic effect of the vaccine and a significant attenuation of pre-existing infection in cows naturally infected with paratuberculosis that were adults at the time of vaccination.

No evidence that wild red deer (Cervus elaphus) on the Iberian Peninsula are a reservoir of Mycobacterium avium subspecies paratuberculosis infection.

The potential role of red deer (Cervus elaphus) as a reservoir of Mycobacterium avium subspecies paratuberculosis (MAP) infection is largely unknown. A total of 332 wild red deer were investigated using post-mortem examination, bacteriology and serology. Only three animals (1.12%) were found to have lesions on histopathological examination and no MAP bacteria were recovered on culture. The results suggest it is unlikely that wild red deer make a significant contribution to the maintenance of MAP infection in the region. The cross-reactivity of the ELISAs used indicates this diagnostic modality is ineffective in the detection of MAP infection in this species. The implications of these results for the control of this important pathogen in both livestock and wildlife are discussed.

Fate of Mycobacterium avium subsp. paratuberculosis after application of contaminated dairy cattle manure to agricultural soils.

Details regarding the fate of Mycobacterium avium subsp. paratuberculosis (basonym, Mycobacterium paratuberculosis) after manure application on grassland are unknown. To evaluate this, intact soil columns were collected in plastic pipes (lysimeters) and placed under controlled conditions to test the effect of a loamy or sandy soil composition and the amount of rainfall on the fate of M. paratuberculosis applied to the soil surface with manure slurry. The experiment was organized as a randomized design with two factors and three replicates. M. paratuberculosis-contaminated manure was spread on the top of the 90-cm soil columns. After weekly simulated rainfall applications, water drainage samples (leachates) were collected from the base of each lysimeter and cultured for M. paratuberculosis using Bactec MGIT ParaTB medium and supplements. Grass was harvested, quantified, and tested from each lysimeter soil surface. The identity of all probable M. paratuberculosis isolates was confirmed by PCR for IS900 and F57 genetic elements. There was a lag time of 2 months after each treatment before M. paratuberculosis was found in leachates. The greatest proportions of M. paratuberculosis-positive leachates were from sandy-soil lysimeters in the manure-treated group receiving the equivalent of 1,000 mm annual rainfall. Under the higher rainfall regimen (2,000 mm/year), M. paratuberculosis was detected more often from lysimeters with loamy soil than sandy soil. Among all lysimeters, M. paratuberculosis was detected more often in grass clippings than in lysimeter leachates. At the end of the trial, lysimeters were disassembled and soil cultured at different depths, and we found that M. paratuberculosis was recovered only from the uppermost levels of the soil columns in the treated group. Factors associated with M. paratuberculosis presence in leachates were soil type and soil pH (P < 0.05). For M. paratuberculosis presence in grass clippings, only manure application showed a significant association (P < 0.05). From these findings we conclude that this pathogen tends to move slowly through soils (faster through sandy soil) and tends to remain on grass and in the upper layers of pasture soil, representing a clear infection hazard for grazing livestock and a potential for the contamination of runoff after heavy rains.

Lack of evidence of paratuberculosis in wild canids from Southwestern Europe.

Wild carnivores are at the top of the trophic chain. They are predators and carrion consumers, and thus, prone to come in contact with disease agents contaminating the environment or infecting live or dead animals. We hypothesized that wild canids could be used as sentinels for the detection of regions with higher Mycobacterium avium paratuberculosis (MAP) prevalence in wild and domestic animals. To test this hypothesis, we set up an ELISA to test 262 wolf (Canis lupus) and fox (Vulpes vulpes) sera for MAP-specific antibodies and processed a subset of samples for culture (n = 61), MAP-specific PCR (15) and histopathology (14). In wolves, the optical density (OD) values in the ELISA were continuously distributed. Ten fox sera (4%) had OD readings of over twice the mean, suggesting contact with mycobacteria. However, all samples tested by PCR were negative for both IS900 and ISMAP02 sequences, and samples cultured for MAP yielded no growth. No visible paratuberculosis or tuberculosis-compatible lesions were recorded. On histopathological examination, no lesions compatible with mycobacterial diseases were observed. These results suggest that wild canids show little or no evidence of paratuberculosis and are unlikely to be useful sentinels for the detection of MAP in Southwestern Europe.