Risk factors associated with Mycoplasma agalactiae infection of small ruminants in northern Jordan

Serological detection of Mycoplasma agalactiae was carried out in 104 small ruminants flocks consisting of 18 sheep, 27 goat and 59 flocks containing both sheep and goats in northern Jordan between 2002 and 2003. At least 5 serum samples per flock were tested using an indirect ELISA for antibodies to M. agalactiae. To increase the chances of detecting this mycoplasma, sick or older animals were sampled. A high seropositivity to M. agalactiae was found in small ruminants suggesting a major role for M. agalactiae in contagious agalactia in northern Jordan. There was no significant difference in the seroprevalence of M. agalactiae in sheep and goats at flock level (X(2)=0.14, d.f.=1, p=0.7). A total of 31 variables including production and health management practices were tested as risk factors for seropositive flocks and analyzed using logistic regression analysis. Increasing risk factors for M. agalactiae seropositive flocks were: using outsider rams, improper cleaning of the milking utensils and separating young from dam, with odds ratios of 5, 3, 4.2, respectively; having mastitis problems in the flock was negatively associated (p=0.04) with M. agalactiae seropositivity. Educating small ruminant farmers to avoid the use of outsider rams, ensuring adequate cleaning of milking utensils and separating the young from dams would enhance the health of small ruminants.     

Anatomic location of Mycoplasma mycoides subsp. capri and Mycoplasma agalactiae in naturally infected goat male auricular carriers

This study sought to determine whether male goat auricular carriers of mycoplasmas known to cause contagious agalactia could harbour these microorganisms at anatomical sites other than the ears. A microbiological study was conducted in 6 naturally infected bucks that had been diagnosed as chronic auricular asymptomatic carriers of Mycoplasma (M.) mycoides subsp. capri (Mmc) more than one year previously. To detect mycoplasmas, cultures and PCR were performed on 46 samples taken from each goat from the cardio-respiratory, digestive, nervous, lymph and genitourinary systems and several joints. Of a total of 274 samples analyzed, 28 were positive for mycoplasmas (10.1%): Mmc was detected in 17 (6.1%), Mycoplasma (M.) agalactiae in 12 (4.3%) and both microorganisms were identified in one of the samples. In all 6 goats, mixed infection was observed despite none being auricular carriers of M. agalactiae. Mycoplasma spp. were identified at 15 different sites; the most frequent sites being the joints (31.2%, 5 positive samples), lymph nodes (25%, 4 positive samples) and respiratory tract (25%, 4 positive samples). Positive results were also obtained in three brain tissue (18.7%), two cardiac tissue (12.5%) and one ileum, urethra, testicle and bulbourethral gland (6.25%) samples. The histopathological findings may suggest the presence of mild chronic conditions in some of the organs where the bacteria were found. Our findings reveal for the first time the capacity of Mmc and M. agalactiae to colonize several other organ systems in chronically naturally infected auricular carriers, possibly representing an added risk factor for the spread of these microorganisms. In the case of M. agalactiae, colonization seemed to be independent of the animal's auricular carrier state.     

Molecular basis of Mycoplasma agalactiae pathogenicity

Compared to other bacterial pathogens, the current knowledge of the molecular basis of pathogenicity of mycoplasmas is limited, and their strategies of infection at the molecular and cellular level remain to be elucidated. Several studies in the past years have shown that pathogenic mycoplasmas are equipped with sophisticated genetic systems, which allow these agents to spontaneously change their surface antigenic make-up. It is implicated that these variable surface components provide the wall-less mycoplasmas with a means to avoid the host immune response and promote host colonization. In Mycoplasma (M.) agalactiae, the agent of "contagious agalactia" in sheep and goats, a pathogenicity island-like locus has recently been identified that contains six distinct but related genes which encode the major immunodominant membrane proteins, the so-called Vpmas. It was shown that these surface-associated proteins vary in expression at an unusual high frequency due to site-specific DNA rearrangements. The previous lack of tools to genetically manipulate M. agalactiae has hampered more refined studies to assess the exact function of Vpmas in M. agalactiae infection and disease. The recent successful introduction of foreign DNA into the M. agalactiae genome therefore represents an important breakthrough which sets up the basis for a variety of follow-up studies assessing the role of Vpmas in molecular pathogenesis.     

Microbiological survey for Mycoplasma spp. in a contagious agalactia endemic area

In this work, we report a microbiological survey for Mycoplasma spp. undertaken between 2001 and 2002 in 28 goat herds in Gran Canaria, Spain, an area where contagious agalactia is endemic. All herds were randomly selected and represented approximately 15.5% of the total goat population of the island. A variable number of milk, articular and auricular swab samples were collected from each flock and cultured in specific mycoplasma culture media. There was a total of 38.5% positive flocks from which 37 mycoplasma isolates were obtained. In contrast with previous data obtained in Spain, our results showed that the large colony variant of M. mycoides subsp. mycoides (Mmm LC) was the most commonly isolated agent associated with contagious agalactia. This species was isolated from 90% of the positive herds and accounted for 54.1% of all isolations. M. agalactiae was isolated from 40% of the positive herds (27% of all isolations) and in six herds M. arginini was isolated (18.7% of all isolations). No M. capricolum or M. putrefaciens strains were isolated. Mycoplasmas were isolated from 21 milk samples, 15 ear canals swabs and one articular sample. The association of several species was reported in several herds. These results are at variance with previous serological studies, which indicated a higher disease prevalence, and suggest that it could be necessary to use detection techniques such PCR to confirm the existence of contagious agalactia in goats.     

Eradication of virulent footrot from sheep and goats in an endemic area of Nepal and an evaluation of specific vaccination

Programmes based on the identification and treatment of cases and the culling of animals refractory to treatment had failed to eradicate virulent footrot from two districts in the western region of Nepal. From 1993 to 1996 vaccination against two endemic virulent strains of Dichelobacter nodosus was tested for its potential to contribute to the eradication of footrot from the region. Only sheep and goats which had been free of signs of footrot at three inspections at monthly intervals before their annual migration to alpine pastures were eligible for inclusion. From November 1992, the treatment of cases identified during inspections included the injection of specific vaccine. Successfully treated cases migrated with their flocks but were excluded from the vaccine trial. Non-responding cases were culled. Forty combined flocks of sheep and goats (approximately 9500 animals) were used initially to compare three vaccination regimens. Eleven flocks (sheep and goats) were treated with two doses of specific vaccine (group A), nine (sheep and goats) were treated with commercial vaccine followed by specific vaccine (group B) and 10 (sheep and goats) were treated with two doses of commercial vaccine (group C) in March to April 1993 before the annual migration; 10 flocks (sheep and goats) remained unvaccinated (group D). Only sheep and goats free of signs of footrot were allowed to migrate. Nevertheless, virulent footrot recurred in many flocks three months later. However, its prevalence was significantly lower in group A than in the other three groups combined. Groups A, B and C then received the specific vaccine before their migrations in 1994 to 1996; group D remained unvaccinated. The annual programme of inspection and identification and treatment of cases continued for seven years, but the vaccinations ceased after four years. There was no recurrence of virulent footrot after November 1993. After the first season the virulent strains of D nodosus used in the specific vaccine could no longer be isolated, although antigenically distinct, benign strains of the organism persisted in cases of benign footrot.     

Comparison of three enzyme-linked immunosorbent assays for serologic diagnosis of contagious agalactia in sheep.

Serologic diagnosis of ovine contagious agalactia (Mycoplasma agalactiae) with the enzyme-linked immunosorbent assay (ELISA) developed by Agence Fran?aise de Sécurité Sanitaire des Aliments (AFSSA) may produce a few false-positive (FP) and false-negative (FN) results. When the prevalence of disease is low, these erroneous results may generate problems for eradication schemes. To prevent this, 2 commercial ELISAs were compared with the AFSSA ELISA. Flocks of known status were selected and classified into 4 categories: true positive (TP), FP, true negative (TN), and FN; 20 sheep per flock were submitted for blood sampling. A flock was considered positive when at least 1 out of 20 sera was positive or 2 sera were doubtful. In the flock, the diagnostic sensitivity of the 3 kits was very good (100%), and the diagnostic specificity showed an improvement from 46% (AFSSA test) to 88% and 92% (commercial tests). Considering individual animals, very few positive ewes were detected within TN or FP flocks; the proportion of positive ewes varied greatly from one kit to another (48% to 82%) within TP flocks. The kinetics of antibody response in sheep experimentally infected with various field strains of M. agalactiae were quite similar with all 3 ELISAs. The agreement between the 3 tests, assessed using the kappa value, varied from moderate to good (respective values of 0.56, 0.61, and 0.86). The 2 commercial ELISAs showed better performances, probably because of a superior analytical sensitivity, and are a good alternative for the serodiagnosis of contagious agalactia in sheep.     

Pilus ELISA and an anamnestic test for the diagnosis of virulent ovine footrot and its application in a disease control program in Nepal

The immunological memory (anamnestic) responses in sheep recovered from virulent footrot (VFR) can be aroused by subcutaneous injection of outer membrane protein (OMP) antigens of Dichelobacter nodosus. The magnitude of this response is directly correlated to the highest antibody response attained during infection and memory lasts at least a year after recovery from VFR. However, some older animals show non-specific responses to OMP antigens. In this study an evaluation of D. nodosus pilus antigen for the anamnestic diagnosis of footrot in sheep was undertaken. The results indicated that the primary and anamnestic responses to pilus were similar in character to OMP antigen but were highly specific. The sensitivity of the procedure for detection of sheep with a history of VFR was approximately 80%. A low proportion of sheep with mild lesions due to virulent strains of D. nodosus reacted to anamnestic challenge. Anamnestic challenge with 10 microg pilus was used in a VFR surveillance program in migratory sheep flocks in Nepal. Conventional diagnostic methods could not be applied during the disease transmission periods in these flocks because of their migration to alpine pastures far away from human habitation. The results supported clinical and bacteriological findings suggesting that virulent strains of D. nodosus have apparently been eliminated from these flocks in Nepal.     

Serological classification and virulence determination of Dichelobacter nodosus isolated from Alberta and British Columbia sheep.

Ovine footrot is a contagious disease of sheep that occurs in temperature climates. It is caused by the strict anaerobe, Dichelobacter nodosus. Benign and virulent organisms are differentiated according to serotype and protease production. This study was conducted to identify the presence of virulent serotypes of D. nodosus in sheep flocks in Alberta and British Columbia. Dichelobacter nodosus was detected in lame sheep from 11 of 15 (73%) flocks in Alberta and in 4 of 5 (80%) British Columbia flocks. It was recovered from 57 of 107 (53%) lame sheep. In Alberta, 4 distinct serotypes were isolated from the 11 positive flocks while in British Columbia a total of 6 different serotypes were isolated. One British Columbia isolate could not be classified into existing serotypes. Of the 19 field strains tested, all but 3 were defined as virulent based upon the rapid rise in protease activity in vitro which was maintained between 3 and 5 d. The knowledge of the serotype and virulence of the D. nodosus isolated from affected animals can assist in the control and prevention of ovine footrot.     

Use of an ELISA for differential diagnosis of Mycoplasma agalactiae and M mycoides subspecies mycoides (LC) in naturally infected goat herds.

Contagious agalactia is an ovine and caprine mycoplasmosis which manifests as mastitis, arthritis and keratoconjunctivitis. Mycoplasma agalactiae is recognised as a causal agent but M mycoides subspecies mycoides (LC), and M capricolum may also be responsible for this syndrome in goats. The clinical signs are not pathognomonic; diagnostic procedures are based on isolation of the organism from diseased animals or by detection of seroconversion. An ELISA specific for M agalactiae and M m mycoides (LC) is described. The specificity of the antigens was demonstrated by immunoblotting and by ELISA using monospecific hyperimmune rabbit sera. A correlation of ELISA activity with other serological tests and isolation of mycoplasmas was carried out in two goat herds under field conditions. Results indicate the ability to detect subclinical mycoplasma infection and individual carrier goats on the basis of ELISA, a finding which will assist control procedures.     

The virulence of Dichelobacter nodosus,measured by the elastase test,is an important predictor for virulent footrot diagnosis in New South Wales sheep flocks

Ovine footrot is a contagious bacterial disease that causes foot lesions, and depending on the virulence of the causative strains, may lead to severe underrunning of the hoof and lameness. Virulent footrot can be identified, treated and controlled more effectively than less virulent benign forms. The in vitro elastase test for virulence of the causative bacteria, Dichelobacter nodosus, has been used to support clinical diagnosis. However, not all laboratory-designated virulent D. nodosus strains cause clinical signs of virulent footrot. This study evaluated retrospectively how well the elastase test supported clinical footrot diagnosis in 150 sheep flocks examined for suspect footrot in New South Wales between August 2020 and December 2021. Flocks were included if measures of clinical disease, environmental conditions and the virulence of D. nodosus isolates were available. Variation in the elastase activity result between D. nodosus isolated from the same flock made bacterial virulence hard to interpret, but calculating the mean elastase rate for all isolates from the same flock made correlations between bacterial virulence and flock footrot diagnosis possible. Simplifying bacterial virulence into whether there were any elastase-positive D. nodosus isolates before 12 days increased the predictive value of elastase results for virulent diagnosis, compared with using the first day that any isolate was elastase positive or the percentage of elastase-positive isolates by 12 days, but not all clinically virulent flocks had isolates with elastase activity before 12 days. Logistic regression models were fitted to identify the minimum number of predictors for virulent footrot diagnosis, with models suggesting that virulent footrot diagnosis was best predicted by adding the elastase test result and environmental conditions to the prevalence of severe foot lesions (score 4 and 5). However, performing the same analysis with different breeds, ages of sheep and seasons might highlight other factors important in the diagnosis of virulent footrot.     

Diagnosis of psoroptic sheep scab with an improved enzyme-linked immunosorbent assay

An enzyme-linked immunosorbent assay (ELISA) was developed for the detection of specific antibodies against crude Psoroptes antigen. The diagnostic sensitivity was 93.7% in 191 sheep with clinical signs associated with mange. These animals originated from 29 flocks in which psoroptic mites were detected. All of 59 sheep infested with Psoroptes ovis were seropositive. Additionally, in 49% of 70 clinically unaffected sheep originating from P. ovis-infested flocks, specific antibodies could be detected, suggesting that asymptomatic infestations can be diagnosed by serology. The specificity of the ELISA was 96.5% as determined with 254 sheep originating from 44 flocks without clinical mange. Cross-reactivity in a low range was detected with selected sera of sheep with clinical chorioptic or forage mite infestations. Four sheep seroconverted 2 weeks after experimental P. ovis infestation, i.e. 2 weeks before clinical signs became obvious. After successful doramectin treatment of 14 sheep with naturally acquired P. ovis infestation, the ELISA values declined slowly but remained positive in seven cases beyond 17 weeks.     

A serological investigation of caseous lymphadenitis in four flocks of sheep

A double antibody sandwich ELISA developed by ID-DLO, Lelystad to detect Corynebacterium pseudotuberculosis infection was used on 329 sheep from four pedigree Suffolk flocks in which clinical cases of caseous lymphadenitis (CLA) had occurred. At subsequent necropsy, typical CLA lesions were seen in 133 sheep, and the diagnosis was confirmed on culture. Lesions were most commonly seen in lungs (n = 46), parotid lymph nodes (n = 44), prescapular lymph nodes (n = 38) and mediastinal lymph nodes (n = 31). The sensitivity of the ELISA test for detecting culture-positive sheep was 0.88, while the specificity of the test was 0.55. The antibody ELISA detected 87.5 per cent of sheep that had CLA lesions restricted to internal organs only. It was concluded that the ELISA test has a valuable role in detecting sheep with both clinical and subclinical CLA.     

奶牛乳腺炎无乳链球菌的分离鉴定

无乳链球菌是比较常见的导致奶牛乳腺炎的病原菌,该菌也是山羊、绵羊慢性乳房炎的病原菌之一,也能引起婴儿败血症、脑膜炎和肺炎等。人医临床上对该菌以B群链球菌相称。试验从内蒙古呼和浩特市周边5个牛场中患有乳房炎的病牛中采集120份乳样,通过分菌培养、形态学观察、生化试验,鉴定出14株无乳链球菌,同时对这14株菌进行了药物敏感试验、动物致病性试验等。试验结果发现,所分离到的无乳链球菌对青霉素类、氨基糖苷类药物高度敏感,对磺胺类、氟哌酸、喹诺酮类药物中度敏感。动物致病性试验对小鼠的致死率达到80%以上。     

Infectious sinusitis in coturnix quails in Brazil

In Brazil, mycoplasmas were isolated from the sinuses of Japanese quails (Coturnix coturnix japonica) from two commercial flocks affected with sinusitis. The major respiratory signs and gross lesions are described. Based on serological and biochemical results, the mycoplasmas isolated were identified as Mycoplasma gallisepticum. One of the isolates was pathogenic for chickens.     

Classification and identification of ovine and caprine Mycoplasmas.

The purpose of this investigation was to give a survey of the classification of ovine/caprine mycoplasmas as a basis for the identification of strains isolated from sheep and goats. A total of 13 strains representing 13 species and/or serogroups were biochemically examined, and serological cross-titrations were performed using metabolism inhibition, growth inhibition and immunofluorescence. Serogroup 6 (Al-Aubaidi) was found to be identical with Mycoplasma capricolum.The results of identification of 57 isolates, sent to the reference centre from different countries, are given.On the basis of the above investigations and a comparison of some of the classification systems described in the literature, it is concluded that the following species have been isolated from goats and/or sheep: M. agalactiae, M. arginini, M. bovis, M. capricolum, M. conjunctivae, M. mycoides subsp. capri, M. mycoides subsp. mycoides, M. ovipneumoniae, M. putrefaciens, Acholeplasma granularum, A. laidlawii and A. oculi. In addition, both Ureaplasmas and strains representing 6 serogroups (groups 5, 7, 10 and 11 of Al-Aubaidi and groups 17 and 18 of Cottew) have been isolated. These serogroups ought to be finally species-classified as soon as possible. kw|Keywords|k]ovine/caprine mycoplasmas; k]classification; k]identification     

First isolation of Histophilus somni from goats

Histophilus somni (former name: Haemophilus somnus) is a Gram-negative, facultative pathogen bacterium that colonises the mucous membranes of cattle and sheep, however it was also described in American bison and bighorn sheep. It can cause local or generalised diseases and asymptomatic carriers can also occur. The presence and the etiological role of this microorganism have not been confirmed in any other domesticated species yet. The purpose of this study was to prove the presence of H. somni in goats by bacterial isolation. Nasal, vaginal or praeputial swab samples were collected from 205 goats in 10 flocks. H. somni strains were isolated from 2 out of 10 flocks; in one flock 10 H. somni strains were isolated from the genital mucosa of 17 goats, while a single H. somni strain was cultured from a vagina of 26 animals in the other flock. Partial amplification and sequencing of the 16S rRNA gene of three H. somni strains verified the identification. The comparative examination of carbon source metabolism using the Biolog Microstation ID System (Biolog, Ca) showed a close relationship of the caprine strains, while they were less related to H. somni type strain CCUG-36157 of bovine origin. H. somni strains were isolated only in the oestrus season from goat flocks with sheep contact. This is the first paper on isolation of H. somni from goats.     

Frequency of excretion of group B streptococci (Streptococcus agalactiae) in the milk during subclinical forms of mammary gland diseases in cows

The milk excretion of group B streptococci (Streptococcus agalactiae) from the udder quarters was examined in thirty cows of a heavily infected herd. Six samplings were performed in ten- to fourteen-day intervals. With respect to excretion rate, the set of cows could be divided into three groups: 1. group of cows excreting S. agalactiae from all udder quarters permanently and absolutely regularly; 2. cows excreting S. agalactiae regularly only from some quarters, certain quarter being negative at all samplings; 3. cows excreting streptococci from all quarters absolutely irregularly, without any conclusive order or dependence. The cytological picture of all samples exhibited no signs of inflammation. The discussion deals with some factors that may influence the excretion of streptococci with milk.     

Update on footrot in south-west Germany

82 Dichelobacter nodosus strains isolated from 9 footrot affected sheep flocks in south west Germany were serotyped and tested for virulence. Serovar B was present in all flocks, representing 64.4% of all isolated D. nodosus field strains. Other serovares found were type A, C, E, G and H. Virulent strains were identified in 5 flocks, while intermediate strains were isolated from all 9 flocks. All serological untypeable strains proved to be avirulent. Based on these epidemiological findings the use of currently available commercial footrot vaccines is appropriate in south west German sheep populations.     

Suspected sheep-associated malignant catarrhal fever in a zero-grazed dairy herd in Kenya

An outbreak of a disease characterised by very high mortality occurred in a group of nine calves (1B4 months old) in a zero-grazing unit 2-3 weeks after an introduction of an apparently healthy alien sheep into the calf pen. Five of the six calves which contracted the disease died. The main clinical signs observed were marked depression, persistently high body temperature (40,5-41,5 degrees C), copious mucopurulent nasal and ocular discharges, dyspnoea, bilateral keratoconjunctivitis with corneal opacity, enlargement of the superficial lymph nodes and marked erythema and/or superficial erosions of the buccal mucosae. At necropsy there were lesions in the upper respiratory and digestive tracts, lymph nodes, brain, eyes, liver, kidneys and the urinary bladder.The lesions were histopathologically characterized by fibrinoid vasculitis which was accompanied by lymphocytic infiltration in the parenchyma of the affected tissues. Based on the evidence of contact between the calves and the recently introduced foreign sheep, the characteristic clinical signs and histopathological findings, a diagnosis of sheep-associated malignant catarrhal fever was made.