Paratuberculosis, a chronic disease affecting ruminant livestock, is caused by Mycobacterium avium subsp. paratuberculosis (MAP). It has direct and indirect economic costs, impacts animal welfare and arouses public health concerns. In a survey of 48 countries we found paratuberculosis to be very common in livestock. In about half the countries more than 20% of herds and flocks were infected with MAP. Most countries had large ruminant populations (millions), several types of farmed ruminants, multiple husbandry systems and tens of thousands of individual farms, creating challenges for disease control. In addition, numerous species of free-living wildlife were infected. Paratuberculosis was notifiable in most countries, but formal control programs were present in only 22 countries. Generally, these were the more highly developed countries with advanced veterinary services. Of the countries without a formal control program for paratuberculosis, 76% were in South and Central America, Asia and Africa while 20% were in Europe. Control programs were justified most commonly on animal health grounds, but protecting market access and public health were other factors. Prevalence reduction was the major objective in most countries, but Norway and Sweden aimed to eradicate the disease, so surveillance and response were their major objectives. Government funding was involved in about two thirds of countries, but operations tended to be funded by farmers and their organizations and not by government alone. The majority of countries (60%) had voluntary control programs. Generally, programs were supported by incentives for joining, financial compensation and/or penalties for non-participation. Performance indicators, structure, leadership, practices and tools used in control programs are also presented. Securing funding for long-term control activities was a widespread problem. Control programs were reported to be successful in 16 (73%) of the 22 countries. Recommendations are made for future control programs, including a primary goal of establishing an international code for paratuberculosis, leading to universal acknowledgment of the principles and methods of control in relation to endemic and transboundary disease. An holistic approach across all ruminant livestock industries and long-term commitment is required for control of paratuberculosis. Electronic supplementary material The online version of this article (10.1186/s12917-019-1943-4) contains supplementary material, which is available to authorized users.
With the exceptions of Bacillus cereus and Bacillus anthracis, Bacillus species are generally perceived to be inconsequential. However, the relevance of other Bacillus species as food poisoning organisms and etiological agents in nongastrointestinal infections is being increasingly recognized. Eleven Bacillus species isolated from veterinary samples associated with severe nongastrointestinal infections were assessed for the presence and expression of diarrheagenic enterotoxins and other potential virulence factors. PCR studies revealed the presence of DNA sequences encoding hemolysin BL (HBL) enterotoxin complex and B. cereus enterotoxin T (BceT) in five B. cereus strains and in Bacillus coagulans NB11. Enterotoxin HBL was also harbored by Bacillus polymyxa NB6. After 18 h of growth in brain heart infusion broth, all seven Bacillus isolates carrying genes encoding enterotoxin HBL produced this toxin. Cell-free supernatant fluids from all 11 Bacillus isolates demonstrated cytotoxicity toward human HEp-2 cells; only one Bacillus licheniformis strain adhered to this test cell line, and none of the Bacillus isolates were invasive. This study constitutes the first demonstration that Bacillus spp. associated with serious nongastrointestinal infections in animals may harbor and express diarrheagenic enterotoxins traditionally linked to toxigenic B. cereus.Members of the Bacillus genus are ubiquitous soil microorganisms that frequently contaminate foods (21,22,26). With the exceptions of Bacillus anthracis and Bacillus cereus, Bacillus species are generally perceived to be inconsequential and of little clinical significance (8). A number of food poisoning incidents can be attributed to B. cereus, and this bacterium is known to cause a variety of nongastrointestinal diseases as well as two different types of food poisoning (for reviews, see references 12, 19, 21, and 22), which are characterized by either diarrhea or emesis. The diarrheal type is attributed to heatlabile enterotoxins, namely, the hemolysin BL (HBL) and nonhemolytic enterotoxin protein complexes, and to a B. cereusrelated enterotoxic protein T (BceT). In B. cereus strain F837/ 76, the three HBL components are encoded by an operon containing hblC, hblD, and hblA, in that order, which respectively encode two lytic components designated L 2 and L 1 and a binding component designated B (30). We recently reported on the abilities of different clinical and food isolates of B. cereus and other Bacillus spp. to express diarrheal enterotoxins HBL and BceT after growth in reconstituted infant milk formulae (26). Previous research has also shown that 14 different Bacillus species isolated from raw milk and from the farm environment may have the potential to produce diarrheal enterotoxins (4). The emetic type is caused by a heat-stable dodecadepsideptide, cereulide (21).The relevance of other Bacillus species as food poisoning organisms and as etiological agents in nongastrointestinal infections, including local, deep-tissue, and systemic infections, is being increas...
A substantial proportion of the causes of infectious bovine abortion remain largely undiagnosed, potentially due to the presence of previously unrecognised infectious agents. Recently, several reports have demonstrated the presence of Parachlamydia sp. in placental and foetal tissues derived from bovine abortions of unknown aetiology but the route of transmission remains undefined. The drinking water from one such recent case study was analysed for the presence of Parachlamydia sp. as a potential source of infection. Chlamydiales sp. 16S rRNA genes were PCR-amplified from the drinking water and a 16S rRNA gene clone library constructed. DNA sequencing of thirty-one clones indicated the presence of organisms belonging to the Parachlamydiaceae, specifically the genera Parachlamydia and Neochlamydia. Seven 16S rRNA gene sequences were identical to a Parachlamydia sp. sequence obtained from placental tissue from an abortion case originating from the same farm. These results raise the possibility that the drinking water is a source of Parachlamydia, which may play a role in infectious bovine abortion.
Three tests were used to measure the circulating immunoglobulin in 381 purchased calves as they entered a commercial calf-rearing unit. A correlation of 0.64 was found between the zinc sulphate turbidity (ZST) test and a quantitative latex agglutination test (LAT) measuring IgG1 (P less than 0.001). A qualitative version of the LAT related poorly to the quantitative version. The proportion of plasma samples identified by the quantitative LAT as having an IgG1 concentration of less than 5 g/litre which were incorrectly identified as positives (greater than or equal to 5 g/litre) by the qualitative LAT was 0.65. The proportion of plasma samples identified by the quantitative LAT as having a IgG1 concentration of greater than or equal to 5 g/litre which were incorrectly identified as negative (less than 5 g/litre) was 0.11. There was no statistically significant relationship between plasma IgG1 concentration and initial liveweight, subsequent overall daily liveweight gain or disease incidence (P greater than 0.05). Calves treated for infectious disease, particularly respiratory disease after weaning, had statistically significantly lower liveweight gains than healthy calves (P less than 0.001).
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