The effect of arsenical dips on Parafilaria bovicola in artificially infected cattle in South Africa

The possible adverse effect of arsenical tick control dips on Parafilaria bovicola infections was investigated in 48 artificially infected cattle. A treatment group of 24 cattle was dipped in a plunge dip containing 1600 ppm arsenic trioxide. A control group of the same size was dipped in an organophosphate dip containing a mixture of chlorfenvinphos and dioxathion. Regular weekly to 3-weekly dipping had no effect initially on the prevalence of ovipositional blood spots of P. bovicola in either group. However, from 4 months after bleeding commenced there was a significant reduction in blood spots in the arsenic-dipped cattle and, on slaughter at 12-14 months after infection, the arsenic group had significantly fewer live worms and fewer carcass lesions. Arsenic residues in muscle samples of treated cattle were 11.6 times higher than in the controls. It is proposed that arsenic residues in the sub-cutaneous muscle layers increase with repeated dipping until a level toxic to P. bovicola is finally reached. Older cattle would therefore be refractory to infection and their carcasses at slaughter would not be affected.     

Characterization and purification of Parafilaria bovicola antigens by chromatofocusing to enhance specificity in serodiagnosis

A study was conducted to determine if the purification of Parafilaria bovicola antigens can increase the specificity of serodiagnosis of parafilariasis in enzyme-linked immunosorbent assay. Antigens released from adult worms of P. bovicola were separated by chromatofocusing on a polybuffer exchanger of the pH range 7.3-4.0 Polypeptide analysis by sodium dodecyl sulphate polyacrylamide gel electrophoresis showed the presence of four major polypeptides with MWs of 41, 36, 24 and 20 kDa. Additional biochemical characterization identified the 24- and 20-kDa polypeptides as hydrophobic glycoproteins. The chromatofocusing purification procedures were also applied for separation of a whole-worm extract. Again, the 41- and 36-kDa antigens were identified in separate peak fractions. Using ELISA, it was shown that the 41- and 35-kDa antigens were recognized by bovine antibodies specific for P. bovicola, but not by other sera collected from cattle infected by Onchocerca gutturosa, Onchocerca lienalis, Ostertagia ostertagi and Dictyocaulus viviparus. The serological evaluation strongly suggests that the 41- and 36-kDa antigens are P. bovicola specific.     

Evaluation of the efficacy of anthelmintics against parafilariosis in cattle

Parafilariosis was first described in South Africa in 1964, thereafter being discovered at numerous localities in the country. When it became obvious that Parafilaria bovicola, for which no treatment was known, caused considerable economic losses, trials involving a series of compounds were conducted to identify candidate remedies. This paper describes an anthelmintic test for evaluating the efficacy of compounds for registration for field use. Recovery of Parafilaria worms is impractical for anthelmintic testing, and consequently the lesion sizes of treated and control groups of cattle are compared statistically, using appropriate statistical tests. The seasonal incidence of mature worm infection in cattle in South Africa is such that trials should commence after June and be completed before the end of January, allowing a lapse of 70 days between treatment and slaughter for resolution of the lesions. The presently available parafilaricidal compounds while of value for treating slaughter stock, when used alone will probably not be effective for control of infection in the field.     

The experimental transmission of Parafilaria bovicola to cattle in South Africa using Musca species (subgenus Eumusca) as intermediate hosts

In controlled experiments in an insect-free stable, cattle became infected with Parafilaria bovicola when Musca lusoria, infected with the larvae of this worm, were allowed to feed on a fresh skin incision, and when infective larvae were placed on fresh skin incisions, injected subcutaneously or into the jugular vein, or instilled into the eyes. The sites of blood spots caused by ovipositing P. bovicola females and the sites of carcass lesions were seldom close to the site of infection, an indication that the worms had migrated. The prepatent period of P. bovicola in 4 cattle which developed blood spots ranged from 242--319 days. Neither of the infected cattle that were kept continuously in a shady stable showed blood spots, but 4 out of 7 infected cattle which spent some time in the sun bled. However, carcass lesions on shaded cattle were similar in appearance to those on cattle kept outdoors. Infective larvae were stimulated to escape from the mouth-parts of infected M. lusoria and Musca xanthomelas s.s. when these were fed citrated ox blood warmed to 38--40 degrees C. No escape took place when the flies were fed warmed saline or warmed 15% sucrose solution.     

Preparation and evaluation of the specificity of Parafilaria bovicola antigen for detection of specific antibodies by ELISA

An enzyme-linked immunosorbent assay (ELISA) for the detection of antibodies in bovine sera against Parafilaria bovicola nematodes was developed and its sensitivity was compared with the immunodiffusion (ID) method. An exoantigen of P. bovicola which was shown to contain four major polypeptides was used in these procedures. The serological reactivity of the antigen polypeptides was defined by using the enzyme-linked immunoelectrotransfer blot technique (EITB) and whole-worm extract proteins. It identified only four serologically reactive polypeptides with sera from one experimentally infected calf and a verified field case. These two positive sera reacted mainly with four major antigens which coincided in molecular weights of the polypeptides of the exoantigenic preparation, namely, 43, 39, 28 and 25 KDa. Calves experimentally infected with P. bovicola showed a positive reaction with ELISA at 4 months after inoculation, and after this period a rapid increase in serum antibody response occurred. In these cases the ID reaction was observed for the first time at 7 months after inoculation. The specificity of an ELISA method using crude exoantigen preparation of P. bovicola was tested for the diagnosis of bovine parafilariasis. No cross-reactivity was detected when the P. bovicola exoantigen preparation was tested against sera from calves experimentally infected with Onchocerca lienalis, as well as against the sera from cattle naturally infected with Dictyocaulus viviparus or from cattle chronically infected with Ostertagia ostertagi. In addition, testing of 740 field sera from cattle in areas non-endemic and endemic for P. bovicola indicated a specificity of the antigen preparation used. Forty sera from laboratory-confirmed field cases of P. bovicola infection were tested by ELISA and immunodiffusion. All of these sera were ELISA positive, whereas only 70% of these were positive in the ID test. Seven (2.1%) of 328 sera from 21 herds from non-endemic P. bovicola areas were ELISA positive, as opposed to none in the ID test. Of the 94 sera from six herds in areas endemic for P. bovicola infection, 51 (54%) were ELISA positive whereas only 24 (26%) were positive in the ID test. When 56 slaughtered cattle, with varying degrees of meat condemnations due to parafilariasis, were tested for P. bovicola specific antibody, 91% of the serum samples were positive by ELISA. These results suggest that the exoantigen of P. bovicola can be used in a sensitive and reliable serological detection of parafilariasis by ELISA.     

Parafilaria bovicola (Tubangui 1934) established in Swedish cattle

Parafilaria bovicola was recorded in Swedish cattle for the first time in 1978. The parasite causes carcass lesions with a maximum incidence from February to July but already in the previous November the carcass lesions appear regularly in the form of yellow oedema. In February and onward the oedema may be extensive with a greenish-yellow colour. The lesions are most prominent in bulls and more or less negligible in cows. However, the cows are considered to be important reservoirs for the parasite from one season to the next. Bleedings are seen from March until August and the infective larvae are transmitted to the cattle from early June by the intermediate host Musca autumnalis. Parafilaria lesions look remarkably like those caused by contusions during handling and transport previous to slaughter. Eosinophile infiltrations can be regarded as a constant diagnostic feature of parafilariosis.     

Studies on Parafilaria bovicola Tubangui, 1934, 2. Chemotherapy and pathology

The filaricidal effects of trichlorphon, arsenic trioxide, sodium antimony biscathecol disulphonate and nitroxynil against Parafilaria bovicola were the subject of this investigation. Levamisole hydrochooride was retested in a separate trial to assess the time required for healing after successful treatment. A comparison of carcass lesions and the percentage of lesion area in untreated controls with those in treated animals reconfirmed the efficacy of levamisole hydrochlorice, while nitroxynil gave more promising results. Both lesions and lesion area were reduced by 76% by the former and by 93% by the latter compound. The other drugs only slightly suppressed P. bovicola activity. After treatment with levamisole hydrochloride, active lesions were still present for 1-4 weeks and visible lesions on slaughter for 8 weeks. Since the visible lesions during the 8 weeks varied from acute to chronic and as they disappeared 9 weeks post treatment, it is suggested that provision should be made for a healing period of at least 9 weeks.     

The control of Parafilaria bovicola transmission in South Africa

Ivermectin treatment of all cattle on a badly infected farm failed to interrupt the transmission of P. bovicola, even though ovipositional blood spots were drastically reduced in numbers for an entire summer season following treatment. Regular weekly to fortnightly dipping of all cattle in 50 ppm deltamethrin immediately reduced vector fly numbers to less than 1 fly per cow face. Sustained dipping for 9 months effectively reduced P. bovicola transmission from approximately 50% to less than 2%. However, cessation of fly control led to a return to predipping P. bovicola infection levels. Ovipositional blood spot counts and the ELISA technique for evaluating P. bovicola infection in a herd were compared and were both effective methods. Best results for the blood spot method, however, are obtained in spring at the peak of the bleeding season whereas the ELISA method does not have this limitation.     

Determination and Health-Risk Evaluation of Nitroxynil Residues in the Edible Tissue of Cattle

A specific Polarographic method with a sensitivity of ≥ 2 jig/kg (ppb) has been used to determine the plasma and tissue concentrations of nitroxynil (NTX), which is used against Parafilaria bovicola in cattle. After treatment with the therapeutic dose on NTX (2 × 20 mg/kg b.w., s,c), there was an initial rapid decrease in the plasma concentration followed by a slower elimination phase. The plasma levels of NTX were 8 mg/kg (ppm) and 3 mg/kg after 6 weeks and 2 months, respectively. The muscle and other edible tissue from treated cattle contained 0.1–0.3 mg/kg NTX after 2 months, and jxg/kg amounts were still detectable 3 months after the injection. Based on available pharmacological and toxicological data, a 3-months withdrawal time for NTX in cattle is proposed.     

The longevity of adult Parafilaria bovicola and the persistence of their associated carcass lesions in cattle in South Africa

The slaughter of naturally-infected heifers and oxen at regular intervals after the first P. bovicola ovipositional blood spots appeared revealed that no female worms with embryonated eggs could be found after 259 days, no live worms after 372 days, and no carcass lesions after 519 days. In one bull, however, blood spots and carcass lesions persisted throughout 2 seasons. With the possible exception of bulls, therefore, annual reinfection of cattle appears to be necessary for the continuation of the transmission cycle of P. bovicola.     

Evidence for bovine parafilariosis in Italy: first isolation of Parafilaria bovicola (Tubangui, 1934) from autochthonous cattle

In May and July 2010 and in March 2011, the presence of multiple bleeding nodules at the level of the neck, shoulders, withers, back and rump in five cattle from three herds in north-central Italy were observed. A diagnosis of parafilariosis was made. Fragments of adult females of Parafilaria bovicola could be identified from the derma of three to five bioptic extirpates. Larvated eggs and free larvae were observed in serohemorrhagic exudates.This paper is the first report of the occurrence of parafilariosis in Italy and subsequent to the various outbreaks reported, it can now be said that bovine parafilariosis is also currently present in Italy.     

Protothecal enteritis as a cause of protein-losing enteropathy in a bull

Prototheca spp are achlorophyllic saprophytic algae found in wastewater, sewage, agricultural waste, and possibly elsewhere in the environment. Infections with these organisms have been reported in cattle, humans, and dogs; affected cattle commonly develop mastitis. A 5-year-old Brahman-cross bull was evaluated because of a history of diarrhea and weight loss. The history and physical examination and clinicopathologic findings were similar to those associated with granulomatous enteritis caused by Mycobacterium avium subsp paratuberculosis (Johne's disease), which is the most common protein-losing enteropathy of cattle. However, diagnostic tests for paratuberculosis yielded negative results. Biopsy specimens from the ileum, jejunum, and ileocecal lymph node were collected for histologic examination and preparation of tissue impression smears; Prototheca-like organisms were identified. Because of the poor prognosis associated with this infection and the lack of safe and economical therapeutic agents for cattle, the owner decided to euthanatize the bull. Infection with Prototheca organisms was confirmed postmortem. As this case illustrates, protothecosis may be a cause of granulomatous enteritis in cattle.     

An infertility problem in a naturally mated herd

Investigation of infertility in a beef herd suggested that IBR virus infection, spread by the bull to susceptible cows during natural mating, was a possible cause. Secondary bacterial infection may have contributed to the problem.     

Multiple hereditary ocular anomalies in a herd of cattle

A Brahman x Santa Gertrudis herd of cows bred to a Hereford bull was evaluated because of a 3-year history of several calves born with congenital blindness. Multiple congenital ocular anomalies in 2 calves included microphthalmos, microcornea, microcoria, heterochromia iridis, microlentia, cataracts, retinal dysplasia, retinal detachment, anterior segment dysgenesis, acorea, and proliferation of the anterior neuroectoderm. On the basis of the lack of environmental factors and persistence of an intermittent problem when breeding to a single bull, a genetic defect was diagnosed as the probable cause. Dominant inheritance with varied expressivity may have best explained the lack of obvious signs in the bull, with emergence of various anterior and posterior segment defects in offspring from unrelated cows.     

Comparison of two sampling tools for diagnosis of Tritrichomonas foetus in bulls and clinical interpretation of culture results.

OBJECTIVE: To compare sensitivity for diagnosing Tritrichomonas foetus infection in bulls using 2 sampling tools and to calculate negative predictive values for infection. DESIGN: Randomized clinical trial. ANIMALS: 30 Bos taurus bulls naturally or experimentally infected with T foetus. PROCEDURE: Preputial scrapings were obtained once/wk for 6 weeks using an artificial insemination pipette and a metal brush; which tool was used first for each bull was randomly determined. Samples were collected first from the left side of the prepuce and then from the right side and placed in commercially available transport media chi 2 Values and confidence limits were adjusted for effect of clustering of results by bull. RESULTS: Significant differences in sensitivity of results were not found between samples collected using the brush or pipette. Using the pipette, sensitivity was estimated to be 91.6% (95% confidence interval, 84.3 to 95.7%); negative predictive values ranged from 41 to 99% for prevalence of infection of 90 to 5%, respectively. Sensitivity was 88.8% for first sample obtained and 96.1% for second sample obtained. CONCLUSIONS AND CLINICAL RELEVANCE: Collection of preputial scrapings with an artificial insemination pipette or a metal brush and use of a commercially available culture system can provide a sensitive diagnostic test for T foetus infection in bulls. Calculated negative predictive values indicated that 1 or 2 tests would suffice in most clinical situations. For bulls from herds in which T foetus is endemic, 2 to 4 tests/bull may be required to ensure that each bull is not infected.     

Estimation of seroprevalence of encephalomyocarditis in Dutch sow herds using the virus neutralization test

Encephalomyocarditis virus (EMCV) has been found on pig farms worldwide and can cause myocarditis in young pigs and reproduction disorders in sows. So far, clinical signs of EMCV have not been reported in the Netherlands. The aim of this study was to estimate the seroprevalence of EMCV infection in Dutch sow herds. A total of 277 Dutch sow herds were randomly selected, from which 3237 serum samples were collected. These samples were tested for EMCV antibodies using the virus neutralization test (VN test). The apparent prevalence of EMCV antibodies was 9.3% in the total sow population, and the apparent herd prevalence was 58.8%. An exact determination of the prevalence of EMCV infections in the Dutch sow population was not possible because the characteristics of the VN test under field circumstances were not known. However, Dutch sow herds seem to be infected with EMCV because the distribution of positive blood samples in the tested sow population was significantly different from that expected if random false-positive reactions had occurred.     

Echocardiographic diagnosis of endocarditis in a bull

A 2-year-old Charolais bull was examined because of lameness that developed after infection of a tail laceration. A systolic murmur was auscultated during the routine physical examination. A diagnosis of endocarditis and polyarthritis secondary to septicemia from the tail lesion was made. The diagnosis was supported by echocardiography and blood cultures, which yielded Corynebacterium pyogenes. The clinical diagnosis was confirmed at necropsy.     

Transmission of Salmonella in dairy herds quantified in the endemic situation

Salmonella is a cause of concern in the cattle industry, because it is a zoonosis causing severe invasive infections in humans and because it causes economic and welfare losses in infected herds. In general, cattle in the Netherlands are infected with two types; Salmonella Dublin and Salmonella Typhimurium. Both types cause clinical signs but S. Dublin outbreaks are more prevalent and clinical signs are more severe than S. Typhimurium outbreaks. Our knowledge of the transmission of Salmonella within herds is still limited, while this is an essential component for modelling the success of intervention strategies to control Salmonella. The aim of our study was to estimate the basic reproduction ratio (R(0)), the number of secondary cases produced from each primary case in a totally susceptible population, for S. Dublin and S. Typhimurium in dairy herds. Serological data were obtained from eight farms with a clinical outbreak of Salmonella, two with an outbreak of S. Dublin and 6 of S. Typhimurium. R(0) was estimated from the serological data of the herds that were in an endemic state of the infection. R(0) across herds was estimated to be 2.5 (95% CI 1.7-9.8) and 1.3 (95% CI 1.1-1.7) for S. Dublin and S. Typhimurium, respectively. The between herd variation was significant and fairly large. The results of the sensitivity analysis showed that the R(0) estimate was not sensitive for changes in the latent, infectious or seropositive periods. The R(0) estimates indicated that the infection would not spread very extensively in susceptible populations under management systems similar to the ones in the study herds.     

Uroperitoneum attributable to ruptured urachus in a yearling bull.

Ruptured urachus was found to result in uroperitoneum in a yearling Beefmaster bull. The uroperitoneum was initially believed to be attributable to ruptured bladder secondary to urolithiasis; however, catheter decompression of the bladder through an ischiatic urethrotomy did not resolve the uroperitoneum. The persistent urachus was diagnosed and removed through caudal right flank laparotomy with the bull standing. The urachus was attached to the umbilicus, communicated with the lumen of the bladder, and had a mucosal lining. Ruptured urachus is an unusual cause of uroperitoneum, but can cause clinical signs identical to those of ruptured bladder. Persistent urachus is a congenital abnormality in many species, but may be hereditary in Beefmaster cattle. In addition, the bull in this report developed hyperkalemia, which is considered an unusual finding in cattle with uroperitoneum.