Validation of a polymerase chain reaction assay for monitoring the therapeutic efficacy of diminazene aceturate in trypanosome-infected sheep

The diagnostic performance of a polymerase chain reaction assay (PCR) for monitoring the effectiveness of aceturate diminazene treatment was compared with those of an antibody-detection ELISA test and the buffy-coat technique using sheep experimentally infected with either savannah-type or forest-type Trypanosoma congolense or T. vivax. Within the period of infection, the PCR using specific savannah-type T. congolense primers showed a significant higher diagnostic sensitivity (p<0.05) than the buffy-coat technique. Both techniques gave closed results for detecting forest-type T. congolense or T. vivax infections. Following trypanocidal treatment, the PCR showed that specific product disappeared definitively 1 or 2 days later in animals in which a decrease of the antibody level and a significant improvement of the red packed cell volume were observed. The occurrence of relapse infection was detected by the PCR in one animal infected by T. vivax on day 19 post-treatment and confirmed by the persistence and increasing antibody level whereas the buffy-coat technique detected parasites 42 days later. Then, the PCR signals remained positive on several occasions while parasitaemia was detected only two times.The application of PCR combined with the antibody detection appeared to provide a useful tool as compared to the buffy-coat technique for monitoring the effectiveness of trypanocidal treatment.     

Failure of dogs to shed oocysts after being fed bovine fetuses naturally infected by Neospora caninum

Neospora caninum is a protozoan that causes abortion in cattle. The dog has recently been identified as a definitive host for N. caninum. To verify if bovine fetuses can infect dogs, nine 2-4-month-old dogs were fed bovine fetuses naturally infected by N. caninum. None of the dogs excreted oocysts, seroconverted, had clinical signs or lesions compatible with N. caninum infection. Additional studies will be necessary to determine the natural mode of infection of dogs by N. caninum.     

Virulence factors in Escherichia coli isolated from the blood of bacteremic neonatal calves

Twenty-five Escherichia coli isolates from the blood of critically ill bacteremic calves sampled in two separate studies on a calf-rearing farm housing over 15,000 calves, in the San Joaquin Valley, California were studied.Isolates were characterized for O serogroups and for pathotypes as determined by the presence of specific virulence factors including heat-labile enterotoxin (LT), heat-stable enterotoxins a and b (STa, STb), verotoxins 1 and 2 (VT1, VT2), cytotoxic necrotizing factor (CNF), aerobactin, intimin Eae and P, F17 and CS31A fimbrial adhesins, and resistance to bactericidal effects of serum.These isolates constituted a heterogeneous group. However, isolates were mostly aerobactin positive and often resistant to the bactericidal effects of serum. Isolates of pathotypes O78 (n=6), O119:CS31a (n=3), and P positive but O non-typeable (n=3) were associated with a high mortality rate. The remaining isolates belonged to diverse pathotypes, often possessing the adhesins P, F17, CS31A and Eae but belonging to O serogroups other than O78 and O119, and were less frequently associated with mortality.Although no virulence factor common to all isolates was identified, the capacity to use iron by the presence of aerobactin which is important to the capture of iron was a predominant factor. Moreover, certain pathotypes appear to be associated with primary colisepticemia whereas other pathotypes may cause a bacteremia without necessarily leading to septicemia.     

Secreted phosphatase activities in trypanosomatid parasites of plants modulated by platelet-activating factor

ABSTRACT The secreted phosphatase activities of two trypanosomatid parasites were characterized and compared with supernatants of living cells. The plant parasite Phytomonas fran?ai and the phytophagous hemipteran parasite Herpetomonas sp. hydrolyzed p-nitrophenylphosphate at a rate of 15.54 and 6.51 nmol Pi/mg of protein per min, respectively. Sodium orthovanadate (N(a)VO(3)) and sodium fluoride (NaF) decreased the phosphatase activities. The phosphatase activity of P. fran?ai was drastically diminished (73% inhibition) in the presence of sodium tartrate, whereas the phosphatase activity of Herpetomonas sp. was inhibited by 23%. Cytochemical analysis showed the localization of these enzymes on the external surface and in the flagellar pocket of the two trypanosomatids. Sodium tartrate inhibited this reaction, confirming the biochemical data. Platelet-activating factor modulated the phosphatase activities, inhibiting P. fran?ai activity and stimulating Herpetomonas sp. phosphatase activity.     

Pyrethroid insecticide residues on vegetable crops

Pyrethroid insecticides were applied on various vegetable crops as foliar treatments to determine dissipation rates. On Chinese broccoli (Guy Lon), Chinese mustard (Pak Choi) and Chinese cabbage (Kasumi, napa), fenvalerate was persistent with residues of 0.10, 0.14 and 0.11 mg kg-1, respectively, by day 21. Cypermethrin residues on head lettuce were below 0.1 mg kg-1 by day 10 but on the leafier romaine and endive varieties it was more persistent and required 14-19 days to dissipate below this concentration. After three applications, residues of cypermethrin in harvested carrots and of permethrin in eggplant were not detected on the day of application. On asparagus, deltamethrin and cypermethrin residues declined to less than 0.1 mg kg-1 by days 1 and 2, respectively; permethrin was more persistent, requiring more than 2 days to decline to less than 0.1 mg kg-1. Deltamethrin on dry (cooking) and Spanish onions was not detected on the day of application. On tomatoes, the concentration of permethrin was 0.093 mg kg-1 on the day of application and declined to about 0.05 mg kg-1 after 2-4 days. In general, permethrin, cypermethrin and deltamethrin residues declined to acceptable concentrations within an acceptable pre-harvest interval. Fenvalerate may be too persistent on these speciality crops unless a maximum residue limit > 0.1 mg kg-1 is permitted.     

ECHOCARDIOGRAPHIC AND DOPPLER DIAGNOSIS: FIRST CASE OF ATRIAL SEPTAL ANEURYSM IN A CAT

A 6-year-old female cat developed pleural and abdominal effusion. Cardiac ultrasound and 2D color tissue Doppler imaging revealed restrictive cardiomyopathy with severe biatrial dilatation and hypertension. This cardiomyopathy was associated with atrial septal aneurysm and a patent foramen ovale. The atrial septal aneurysm involved the entire atrial septum. Necropsy and histological examination confirmed all these findings. ASA is a rare malformation and, as in this cat, it generally occurs concomitantly with congenital or acquired heart disease and may be explained by greater pressure in one atrium, leading to controlateral protrusion of the atrial septum.     

Dilemma of virulence of Streptococcus suis: Canadian isolate 89-1591 characterized as a virulent strain using a standardized experimental model in pigs

Virulence of Streptococccus suis capsular type 2 strain 89-1591 has been controversial in literature. A standardized experimental model with specific-pathogen free piglets was used for a new evaluation of this strain. Twenty-nine piglets were allotted in 4 separated groups. Group 1 consisted of negative control animals which received broth medium. Groups 2, 3, and 4 were intravenously challenged with 2 mL of S. suis, strains 1330, 89-1591, and 166', respectively. The strain 1330 is a recognized avirulent Canadian strain. The strain 166' is a reference French virulent isolate. Pigs inoculated with strain 1330 did not present clinical signs of a S. suis infection. Contamination in organs and bacterial blood circulation were rare and lesions were almost non-existent. Infection of pigs with S. suis strain 89-1591 (group 3) and 166' (group 4) caused severe clinical problems, animals infected with S. suis 166' were the most affected. Pigs presented with clinical signs such as high body temperature, lameness, nervous symptoms, and even mortality. Lesions associated with S. suis were numerous for both strains, but more evident in animals of group 4. It can be concluded that S. suis strain 89-1591 is virulent, although its virulence seems to be lower than that of the French strain. Results of an experimental infection with strain 89-1591 may depend on different factors such as the route of inoculation and the immunological status of the animals used. Using conventional animals, with an unknown status regarding previous S. suis infections, equivocal results may be obtained, and this may explain differences reported by some authors with the same strain.     

Isolation of equine herpesvirus-2 from the lung of an aborted fetus.

This study describes the isolation of equine herpesvirus-2 (EHV-2) from the lung of an aborted equine fetus in Argentina. The isolated virus was confirmed as EHV-2 by indirect immunofluorescence using a rabbit anti-EHV-2 polyclonal antiserum and by virus-neutralization test using an equine polyclonal antibody against EHV-2. Restriction endonuclease DNA fingerprinting with BamHI also confirmed the identity of the virus as EHV-2. Furthermore, viral nucleic acid was detected by polymerase chain reaction from the original lung sample and from the DNA obtained from cells infected with the virus isolate. This work constitutes the first reported isolation of EHV-2 from an aborted equine fetus. The presence of EHV-2 in the lung of the aborted fetus would indicate that this virus is capable of crossing the placental barrier. However, no cause-effect relationship was established between the EHV-2 isolate and the abortion.     

Evaluation of an air-filtration system for preventing aerosol transmission of Porcine reproductive and respiratory syndrome virus

The purpose of this study was to evaluate the ability of a commercial air-filtration system to reduce aerosol transmission of Porcine reproductive and respiratory syndrome virus (PRRSV). The system consisted of a pre-filter and 2 filters with EU8 and EU13 ratings. In each of 4 trials, 5 PRRSV-infected donor pigs and 1 naive recipient pig (each 25 kg) were housed in opposing chambers connected by a 1.3-m-long duct. The system filtered air entering 1 recipient-pig chamber (filtered facility) from the donor-pig chamber but not a 2nd recipient-pig chamber (nonfiltered facility). The donor pigs had been experimentally infected with PRRSV MN-184, an isolate previously documented to be shed at a high frequency in contagious aerosols. On days 3 to 7 after infection of the donors, the 2 groups were housed in their respective chambers for 6 h and then in separate facilities, where samples were collected for testing by polymerase chain reaction and enzyme-linked immunosorbent assay over 14 d. Aerosol transmission was observed in 6 of the 20 replicates in the nonfiltered facility, whereas all pigs remained PRRSV-negative in the filtered facility; the difference was significant at P < 0.01. Thus, under the conditions of this study, the air-filtration system evaluated appeared to be highly effective at reducing aerosol transmission of PRRSV.     

Coagulase gene typing of Staphylococcus aureus isolated from cows with mastitis in southeastern Brazil

A typing procedure based on polymorphism of the coagulase gene (coa) was used to discriminate Staphylococcus aureus isolated from Minas Gerais dairy cows with mastitis. Amplification of the gene from the 64 S. aureus isolates produced 27 different polymerase chain reaction (PCR) products; 60 isolates showed only 1 amplicon, and 4 showed 2 amplicons. The isolates were grouped into 49 types by analyzing the restriction fragment length polymorphism (RFLP) of the coa gene; the 10 most common types accounted for 39% of the isolates. The results demonstrate that many variants of the coa gene are present in the studied region, although only a few predominate.