Herd-level prevalence of Map infection in dairy herds of southern Chile determined by culture of environmental fecal samples and bulk-tank milk qPCR

Serological and epidemiological investigation of Mycobacterium avium subspecies paratuberculosis in bovines in Pakistan

OBJECTIVE

This study aimed to investigate the prevalence of paratuberculosis in cattle and buffaloes at twelve public dairy farms in Punjab, Pakistan.

METHODS

A total of 2,181 more than two-year-old animals (1,242 cattle and 939 buffaloes) were tested by avian tuberculin, i.e., killed purified protein derivative of Mycobacterium avium paratuberculosis and indirect enzyme linked immunosorbent assay (ELISA). Blood and fecal samples were collected from tuberculin positive animals. These samples were further processed by indirect ELISA. The data were analyzed using frequency analysis and logistic analysis procedures.

RESULTS

The prevalence of paratuberculosis at public dairy farms was 3.8%, as determined by tuberculin+ELISA test. It varied from 0.71% to 13.5% with a 100% herd prevalence. Multivariate logistic regression analysis revealed that species, milk production, total animals, total small ruminants, and total buffaloes were significantly associated with the occurrence of paratuberculosis. Odd ratio analysis revealed that with a one-kilogram increase in body weight, there will be a 0.006% increase in disease occurrence. With the increase in one animal in small ruminants and buffaloes, there will be 0.008% and 0.42% greater chances of developing paratuberculosis, respectively. Bivariate logistic regression analysis of cattle and buffaloes revealed that farm number, age, and total number of cattle were significantly associated with the occurrence of paratuberculosis. A one-month increase in lactation length increases the chance of tuberculosis by 0.004%; similarly, a one-liter increase in milk production increases the chance of disease by 10%. With each additional buffalo in the herd, there will be a 0.007% greater chance for the occurrence of paratuberculosis.

CONCLUSION

This study concluded that tuberculin testing can be used in conjunction with ELISA to screen animals for paratuberculosis in countries with scarce resources, such as Pakistan. The efficacy of disease diagnosis can be improved by combining multiple tests.

Association between the severity of histopathological lesions and Mycobacterium avium subspecies paratuberculosis (MAP) molecular diversity in cattle in southern Chile

The objective was to evaluate the association between the severity of histopathological lesions caused by Mycobacterium avium subspecies paratuberculosis (MAP) infection and the molecular diversity of this pathogen. Blood, ileum, and mesenteric lymph node samples were collected at slaughter, from 1,352 adult cattle [source population 1 (SP1)]. In addition, 42 dairy herds (n = 4,963 cows) were followed for 2 years, and samples from compatible paratuberculosis clinical cases [source population 2 (SP2)] were collected. MAP infection was confirmed using an ELISA test, liquid media culture, and PCR. Isolates were genotyped using five MIRU-VNTR markers. Tissues from confirmed samples were subjected to a histopathological examination. A histopathological severity score (HSS) system was developed and used to grade (0 to 5) the magnitude of lesions caused by MAP. In general, the HSS system assesses the number of foci and degree of macrophage infiltration, together with the presence of multinucleated giant cells (MGCs) and acid-fast bacilli (AFB), in addition to the fusion of the intestinal villi and hyperplasia of the crypts. Despite the large sampling effort, only 79 MAP isolates were successfully genotyped, where 19 different haplotypes were described. A mixed-effect Poisson regression model was used to assess the relationship between haplotypes and HSS values. The model was controlled by animal age, and the farm was used as a random effect. Haplotypes were grouped based on their relative frequency: the most frequent haplotype (group i, 49.4%), the second most frequent haplotype (group ii, 12.7%), and all other haplotypes (group iii, 37.9%). Model outputs indicated that group i had significantly higher HSS values than group iii. In addition, group i was also associated with higher optical density (OD) values of the ELISA test. These results support the existence of differences in pathogenicity between MAP haplotypes. However, results were based on a relatively small sample size; thus, these should be taken with caution. Despite this, study findings suggest that haplotypes would be associated with differences in disease progression, where the dominant haplotype tends to generate more severe lesions, which could be linked to a greater shed of MAP cells than non-dominant haplotypes, increasing their chances of transmission.

Bayesian latent class estimation of sensitivity and specificity parameters of the PMS-PCR test for the diagnosis of cattle sub-clinically infected with Mycobacterium avium subsp. paratuberculosis

The objective of this study was to estimate the performance of the peptide magnetic separation PCR test (PMS-PCR) for the diagnosis of Mycobacterium avium subsp. paratuberculosis (MAP) in sub-clinically infected dairy cattle. Twenty-one herds were randomly selected from a source population of 131 commercial dairy herds with a known history of MAP infection, located in the De Los Rios and De Los Lagos regions, in southern Chile. In the selected herds, all milking cows with ≥2 parities and without any clinical signs were sampled, collecting feces and blood-serum samples. The PMS-PCR test was used to analyze the fecal samples, while serum samples were analyzed using a commercial ELISA kit. A Bayesian latent class model was used to estimate the sensitivity (Se) and specificity (Sp) of the diagnostic tests. A total of 1381 animals were sampled in the 21 selected dairy herds, with an average sample size of 65 animals per herd (range 10-721). The PMS-PCR test had a greater Se than the ELISA test, with a median of 85.5 % (posterior probability interval (PPI) 95 %: 79.3-91.0%), while the ELISA test presented a median of 21.7 % (95 % PPI: 18.3-25.4%). On the other hand, the ELISA test had a better Sp than the PMS-PCR test, with a median of 97.7 % (95 % PPI: 96.6-98.5%), whereas PMS-PCR presented a median of 90.8 % (95 % PPI: 88.3-93.9%). Model results showed that PMS-PCR has a better Se than all available tests for MAP diagnosis in subclinical animals. However, this test should be used with care in herds with high infection rates, where a high MAP environmental load is expected, potentially increasing the frequency of false positive cases due to the pass-through phenomenon.

Is the transmission of Mycobacterium avium subspecies paratuberculosis (MAP) infection through milk intended to feed calves an overlooked item in paratuberculosis control programs?

As in many parts of the world, Chile shows a high Mycobacterium avium subsp. paratuberculosis (MAP) infection rate. Evidently, the control recommendations have been inefficient. In the author's opinion, the potential risk of MAP transmission to susceptible calves through milk consumption is largely overlooked. Two observational studies were performed, one to confirm MAP shedding in young stock in a high MAP-infected dairy herd and MAP load in milk intended to feed these calves was estimated. In parallel, in a second study, we estimated the relationship between MAP herd seroprevalence and the cow MAP shedding level as well as the presence of this pathogen in milk used to feed dairy calves. In the first study, 53.7% of cows and 22.5% of calves showed positive culture results. Among all cows tested, 9 (2.19%) animals had a positive serum ELISA, and MAP load in milk reached 10⁶ bacteria/mL. In the second study, three seroprevalence categories were established as follows: high (≥ 9%), medium (> 5% and ≤ 9%), and low (≤ 5%). Statistical significant differences among these categories were observed. Animals from the high seroprevalence category shed significantly more MAP than the others. However, in the low category, heavy shedder animals were also observed. Finally, in all study herds, MAP presence in milk intended to feed calves was reported, even from herds without ELISA-positive animals.

Prevalence of Mycobacterium avium subsp. paratuberculosis infection in dairy herds in Northern Antioquia (Colombia) and associated risk factors using environmental sampling

This cross-sectional study aimed to determine Mycobacterium avium subsp. paratuberculosis (MAP) herd-level prevalence using a quantitative real-time PCR method (qPCR), performed on environmental samples. Secondly, the study aimed to explore herd-level risk factors associated with the presence of MAP in dairy herds with in-paddock milking facilities of the Northern region of the Province of Antioquia (Colombia). Study herds (n = 292) located in 61 different districts from six municipalities were randomly selected amongst 7794 dairies registered in the foot-and-mouth disease vaccination records from 2015. The sampling strategy considered a proportional allocation, both at municipality and district level. Participant herds were visited once between June and October 2016 to collect one composite environmental sample and to complete a risk assessment questionnaire. Each composite environmental sample contained material from six different sites of concentration of adult cattle and/or high traffic areas (e.g. areas surrounding waterers and feeders, areas surrounding the current mobile milking-unit places). Identification of MAP was achieved using a duplex qPCR (Bactotype MAP PCR Kit^®, Qiagen). A herd was considered as MAP infected if the environmental sample was positive in the qPCR. Information about the general characteristics of the herd, management practices, and knowledge about the disease was collected using the risk-assessment questionnaire. The information on risk factors was analyzed using a multivariable logistic regression model. The apparent herd-level prevalence was 4.1% (12/292; 95% CI: 1.8-6.4). Herds with a history of mixed farming of cattle with other ruminants had higher odds of being MAP infected than herds without (OR = 3.9; 95% CI: 1.2-13.2). Our study demonstrates the MAP prevalence in dairy herds from Antioquia, Colombia and the possible relationship between MAP environmental positivity with the history of mixed farming of cattle with other susceptible ruminants.

Mycobacterium avium subspecies paratuberculosis - an important food borne pathogen of high public health significance with special reference to India: an update

This review underlines the public health significance of 'Indian Bison Type' of Mycobacterium avium subspecies paratuberculosis (MAP) and also its potential as 'zoonotic infection'. In the absence of control programs, bio-load of MAP is increasing and if we take total population of animals (500 million plus) and human beings (1.23 billion plus) into account, the number of infected animals and human beings will run into millions in India. Our research on screening of over 26,000 domestic livestock for MAP infection using 4 different diagnostic tests (microscopy, culture, ELISA and PCR), during last 31 years has shown that the average bio-load of MAP in the livestock population of India is very high (cattle 43%, buffaloes 36%, goats 23% and sheep 41%). 'Mass screening' of 28,291 human samples between 2008-2016 revealed also high bio-load of MAP. It has been proved that MAP is not in-activated during pasteurization and therefore live bacilli are continuously reaching human population by consumption of even pasteurized milk and other milk products. Live bacilli have also been recovered from meat products and the environment thus illustrating the potential of MAP as pathogen of public health concern. However, at present, there is inadequate scientific evidence to confirm a conclusive link between MAP infection and Johne's disease in ruminants and some cases of Crohn's disease in human beings.

Paratuberculosis in Latin America: a systematic review

Latin America is the definition of the American group, where languages of Latin origin are spoken, including countries in South, Central, and North America. Paratuberculosis is a gastrointestinal contagious chronic disease that affects ruminants, whose etiological agent is the bacilli Mycobacterium avium subsp. paratuberculosis (MAP). Paratuberculosis is characterized by intermittent diarrhea, decreased milk production, dehydration, and progressive weight loss and is possibly involved in Crohn's disease, a human intestinal disease. MAP is resistant to environmental factors, pasteurization, and water disinfection, which coupled with the subclinical-clinical nature of the disease, and makes paratuberculosis a relevant socioeconomic and public health issue, justifying the descriptive review of research on the disease carried out in Latin American countries. A survey of articles, published until September 2016, on the Scopus database, PubMed, Agris, and Science Direct, about detection of the agent and the disease in Latin America, without restrictions to the date of the research was performed. The keywords were as follows: "paratuberculosis," "Mycobacterium avium subsp. paratuberculosis," "cattle," "milk," "wildlife," "goat," "ovine," "dairy," and the name of each country in English. Studies found from nine of the 20 Latin America countries, 31 related to Brazil, 17 to Argentina, 14 to Chile, eight to Colombia, six to Mexico, two to Peru, two to Venezuela, and one to Panama and to Bolivia, each. The agent was detected in cattle, goats, sheep, domesticated water buffalo, and wild animals. Microbiological culture, PCR, and ELISA were the frequent techniques. The small number of studies may result in overestimation or underestimation of the real scenario.

Evaluation of a Commercial Real-Time PCR Kit for the Detection of Mycobacterium avium subspecies paratuberculosis in Milk

There are several commercial test kits for Mycobacterium avium subspecies paratuberculosis (MAP) detection, each with different advantages, disadvantages, and applications. In the present study, a real-time PCR kit targeting the unique transposon sequence ISMAP02 was evaluated. The analytical sensitivity was determined using the type strain ATCC 19698, and the specificity was validated by testing fifteen MAP isolates, thirteen non-MAP Mycobacterium isolates, and eight non-Mycobacterium isolates. Six spiking experiments were performed using raw milk and reconstituted infant milk artificially contaminated with dilutions containing 10(0)-10(5) MAP cells mL(-1). Sensitivity and specificity were at 100 %. The detection probabilities in raw milk and reconstituted infant milk for the samples (containing 1.4 × 10(1) and 1.7 × 10(1) MAP cell 50 mL(-1)) were 16.6 and 91.6 %, respectively. Thus, the tested kit yielded satisfying results to detect MAP in milk.

Johne's disease: reliability of environmental sampling to characterize Mycobacterium avium subspecies paratuberculosis (MAP) infection in beef cow-calf herds

Environmental samples are considered to be a cost-effective method of identifying Mycobacterium avium subsp. paratuberculosis (MAP)-positive dairy herds, but evidence for beef cow-calf herds is weak. This study aims at evaluating this approach in a total of 20 German herds that were characterized by individual faecal samples (n = 2545) of all cows. For 14 MAP-positive herds having at least one MAP-positive animal, the within-herd prevalence was calculated from concurrent individual faecal culture-based testing. Six herds certified as 'MAP free' based on the negative results of previous years served as MAP-negative controls. On average, six environmental samples were taken at the end of winter from areas with high cow traffic and tested for MAP by faecal culture. According to the environmental samples, nine (64·3%) out of the 14 MAP-positive cow-calf herds were infected. The percentage of positive environmental samples and the apparent within-herd prevalence (Spearman's P = 0·73, P < 0·001) as well as the herd-level test results (positive and negative) and the herd's status based on individual testing (Fisher's exact test, P = 0·014) showed a positive association. Considering limitations in low-prevalence herds, MAP-positive beef cow-calf herds are detectable by environmental samples in temperate climate zones.

Risk factors for Mycobacterium avium subsp. paratuberculosis (MAP) and Mycobacterium bovis coinfection at individual animal level in southern Chile cattle populations

Mycobacterium avium subsp. paratuberculosis (MAP) causes a chronic intestinal infection mainly in domestic and wild ruminants and is transmitted primarily by the fecal-oral route. Mycobacterium bovis (M. bovis) produces a chronic infection principally of the respiratory system. It affects most domestic mammals, wild species, and humans and is spread via the respiratory or oral route. It is important to note that M. bovis is considered a major zoonotic agent. The term coinfection refers to the coexistence of two or more infectious agents in the same host. The goal of the present study was to assess management factors that may favor coinfection with MAP and M. bovis in cattle at an individual level. A cross-sectional study was conducted including 366 cattle from 11 herds. Diagnostic information for both pathogens and individual characteristics of the animals and management practices applied on them was collected from each herd. The results indicated a set of variables being more frequent in the coinfected group of animals and mainly related with biosecurity measures. This study provided regionally based data that may be used to design future control plans for both cattle infections in southern Chile.

Application of cattle slurry containing Mycobacterium avium subsp. paratuberculosis (MAP) to grassland soil and its effect on the relationship between MAP and free-living amoeba

Slurry from dairy farms is commonly used to fertilize crops and pastures. This mixture of manure, urine and water can harbor multiple microbial pathogens among which Mycobacterium avium subsp. paratuberculosis (MAP) is a major concern. Persistence of MAP in soil and infection of soil Acanthamoeba was evaluated by culture, real-time IS900 PCR, and by staining of amoeba with acid-fast and vital stains comparing soils irrigated with MAP-spiked or control dairy farm slurry. MAP DNA was detected in soil for the 8 month study duration. MAP was detected by PCR from more soil samples for plots receiving MAP-spiked slurry (n=61/66) than from soils receiving control slurry (n=10/66 samples). Vital stains verified that intracellular MAP in amoeba was viable. More MAP was found in amoeba at the end of the study than immediately after slurry application. There was no relationship between MAP presence in soil and in amoeba over time. Infection of amoeba by MAP provides a protected niche for the persistence and even possibly the replication of MAP in soils. As others have suggested, MAP-infected amoeba may act like a "Trojan horse" providing a means for persistence in soils and potentially a source of infection for grazing animals.