Adaptive strategies of Pontoscolex corethrurus (Glossoscolecidae,Oligochaeta), a peregrine geophagous earthworm of the humid tropics

Summary Pontoscolex corethrurus is a medium-sized geophagous earthworm species which has invaded most cultivated land in the humid tropics. It is generally found in gardens, cropland and fallowland, where it has been introduced accidentally by man. The species has quite narrow microclimatic requirements. Reproduction only occurs at 23°–27°C, and the worms are fully active only where soil moisture is well above field capacity (pF 2.5). This limitation is balanced by the ability to live in a great Variety of soils differing in pH, organic matter content and texture. The demographic profile is typically of the r type, which gives populations a colonization capacity greater than that of comparable native species. This can be explained by the limited size of individuals and the great efficiency of their mutualist digestion system, in association with the free soil microflora. As a result, growth is fast and a great amount of energy may be invested in reproduction, which is made even more efficient by parthenogenesis.     

Effectiveness of passive gas-scavenging canisters attached to isoflurane anesthesia systems under standard-use conditions in a laboratory animal facility

Chronic exposure to trace levels of waste anesthetic gases has been linked to higher incidences of neurologic and reproductive dysfunction, hepatic and renal toxicity, and neoplasia in health care professionals. We have shown that low levels of isoflurane emissions are likely in conventional laboratory animal treatment rooms during the use of standard anesthesia delivery systems equipped with activated charcoal canisters for passive gas scavenging. In the present study, we surveyed the effectiveness of canisters (attached to well‐maintained precision isoflurane vaporizers) in current use throughout our AAALAC‐accredited laboratory animal facility. Canisters (Omnicon f/air) had been weighed prior to use and then attached to dual‐loop systems (face mask and induction box circuits) from 1 week to 6 months of service. Isoflurane emissions were measured using a pre‐calibrated, portable infrared spectrophotometer by attaching each canister to the face‐mask circuit, occluding the face mask and closing the stopcock to the induction circuit, and running the system at uniform isoflurane concentration (2%) and oxygen flow rate (1 L minute^?1). Samples were taken in animal procedure rooms (size range, 45–80 m³) in which the air turnover rate ranged between 20 and 30 nonrecirculating changes per hour. Nine of the 60 canisters (15%) in current use were found to have exceeded the manufacturer's recommended use‐life (defined as a weight increase of 50 g). Of these nine, seven canisters did not scavenge isoflurane at all (indicated by emissions greatly exceeding 100 ppm). Isoflurane was not detected in the operator's breathing zone under normal use conditions (i.e. gas directed to both circuits at once). Of the 51 canisters that had not exceeded their rated use‐life, 12 (23.5%) exhausted isoflurane at >2 ppm. Our data show that (i) the potential for exposure to waste isoflurane emissions will depend on the configuration of the delivery system and that (ii) enhanced attention to canister surveillance may be warranted even in well‐run facilities.     

Oxidative status during late pregnancy and early lactation in dairy cows

In the last few years, the detection of free radical damage and the body's defences against it have become increasingly important in clinical medicine as a complementary tool in the evaluation of metabolic status. The aim of this study was to evaluate, under field conditions, the anti-oxidant status of healthy cows during late pregnancy and lactation onset using two parameters: (1) plasma levels of malondialdehyde (MDA), a degradation product of lipid peroxidation, and (2) total antioxidant status (TAS). Results were compared with those obtained in another group of cows with lesser metabolic demands. We also investigated possible relationships between antioxidant status markers and other relevant blood parameters. Our results confirmed the characteristic metabolic changes associated with late pregnancy and early lactation. MDA and TAS provided an accurate reflection of the internal physiological status of the animal. The data indicated increased lipid peroxidation around parturition, but with wide individual variations that may be attributable not only to the physiological stage but also to unknown factors that will have to be further considered in future studies.     

Dirofilaria immitis prevalence in a canine population in the Samana Peninsula (Dominican Republic) - June 2001

Dirofilaria immitis, the etiological agent for heartworm disease, is a zoonotic, vector-borne parasite. The dog is the most common natural host. Heartworm disease is present in all US states, as well as in South and Central America, Asia, Europe, Africa and Australia [. Prevalence of feline heartworm disease - a global review. In: Proceedings of the Heartworm Symposium'95, Auburn, Alabama, USA, 31 March-2 April, 1995. American Heartworm Society, Batavia, USA, pp. 79-86]. According to Menda [Menda, J.A., 1989. Transplacental migration of Dirofilaria immitus microfilariae. Companion Anim. Pract. 19 (6-7), 18-20], 18% of the canine population in the city of Santo Domingo tested positive for heartworm using the Filar Assay Kit. In the year 2000, clinical veterinarians from the Samana Peninsula in the Dominican Republic stated that the incidence of heartworm was minimal (Goodman, personal communication). In this small epidemiological study performed during the summer of 2001, 104 dogs from the Samana Peninsula were tested for heartworm antigen with the WITNESS HW Test and a wet mount evaluation for microfilaria under light microscopy. It was found that 18.2% of the canine population tested positive according to either one or both of the diagnostic methods. It would be advisable to apply prevention measures to control Dirofilaria immitis infection in the canine population of the Samana Peninsula in the Dominican Republic.     

A prospective study of vesicular stomatitis in cattle in an enzootic region of Mexico

A prospective study of vesicular stomatitis was conducted in two bovine herds in southeastern Mexico. In July 1987, an initial serological screening showed that 64% and 87% of the 654 cattle tested negatively to vesicular stomatitis New Jersey and Indiana antibodies, respectively, using the plaque-reduction serum neutralization test. Most seropositive animals were at least 24 months of age. Based on the initial serological screening, cohorts of seronegative and seropositive cattle were monitered (January–December 1988) for the prevalence of vesicular stomatitis virus (VSV) antibodies using an enzyme-linked immunosorbent assay (ELISA). The serological results, using ELISA, indicated that no VSV activity occured in the two study herds. The seronegative cohort of cattle did not yield a positive seroconversion pattern to either VSV Indiana or New Jersey. The seropositive cohort showed a variable antibody response pattern against the VSV. There were no clinical cases of vesicular stomatitis (VS) in the two herds. The data from the national surveillance program for vesicular diseases suggested that 1988 was a year of low VSV infection incidence in southeastern Mexico.     

Risk factors for umbilical hernia in Holstein heifers during the first two months after birth

OBJECTIVE: To determine risk factors associated with identification of an umbilical hernia during the first 2 months after birth in Holstein heifers. DESIGN: Case-control study. ANIMALS: 322 Holstein heifers born in a single herd (45 with an umbilical hernia and 277 without). PROCEDURE: Risk factors that were examined included sire, whether the dam had a history of umbilical hernia, milk yield, duration of gestation, whether the dam had a history of dystocia, whether the heifer had a twin, birth weight, total serum protein concentration, and whether the heifer had an umbilical infection. Logistic regression was used to analyze risk factors. RESULTS: Heifers born to sires with > or = 3 progeny with an umbilical hernia were 2.31 times as likely to develop an umbilical hernia as were heifers born to sires with < or = 2 progeny with an umbilical hernia. Heifers with umbilical infection were 5.65 times as likely to develop an umbilical hernia as were heifers without umbilical infection. CONCLUSIONS AND CLINICAL RELEVANCE: Sire and umbilical infection were associated with risk of an umbilical hernia during the first 2 months of life in Holstein heifers. Attributable proportion analysis indicated that the frequency of umbilical hernias in Holstein heifers with umbilical infection would have been reduced by 82% if umbilical infection had been prevented.     

Mycoplasma mycoides subsp. capri associated with goat respiratory disease and high flock mortality

A high mortality outbreak of respiratory mycoplasmosis occurred in goats in Mexico. The clinicopathologic presentation resembled contagious caprine pleuropneumonia caused by Mycoplasma capricolum subspecies capripneumoniae. By using a battery of polymerase chain reaction assays, the mycoplasma associated with this outbreak was identified as Mycoplasma mycoides subsp. capri.     

Ovarian activity in F1 prepubertal ewe lambs under tropical conditions

Seventy crossbred ewe lambs, born from Pelibuey (PB) dams mated with five sire breeds: White Dorper × PB (WD × PB), Black Head Dorper × PB (BHD × PB), Ile de France × PB (Ile × PB) Katahdin × PB (KT × PB) and Pelibuey (PB × PB), were used to determine age and weight to puberty, follicular populations during prepubertal development, ovulation rate at first ovulation and function of the first corpus luteum (FCL). Ewe lambs were maintained under grazing conditions and were supplemented with 300 g head^− 1 day^− 1 of a concentrate with 14% CP and 3.0 Mcal ME kg^− 1 of DM. From 145 days of age, monthly observations were performed by endoscopy to monitor follicular populations and luteal structures. Ovarian follicles were classified according to size into small (≥ 1 and < 3 mm), medium (≥ 3 and ≤ 4 mm) and large (> 4 mm). Additionally, weekly observations by ultrasonography were performed in four ewes per genotype to assess follicular populations. Luteal function from first ovulation was determined by circulating concentrations of progesterone. Ovulation rate was not affected by genotype (P > 0.05). All breed groups had the same pattern of follicular populations, where most of follicles were small, followed by medium and a small proportion of large follicles. Maximum diameter of follicles was similar for all genotypes during prepubertal development (P > 0.05), with an average range of 3.9 ± 0.20 to 4.4 ± 0.20 mm. The BHD × PB reached puberty at the youngest age of 240.9 ± 13.0 days, compared to all other genotypes (P < 0.05), 259.1 ± 11.7 for WD × PB, 279.3 ± 9.6 for KT × PB and 289.0 ± 15.3 days for PB × PB and 308.6 ± 11.9 days for Ile × PB ewe lambs. Ile × PB had greater weight to first ovulation (31.5 ± 1.19 kg) as compared to other breed groups (P < 0.01). The largest percentage of FCL was for KT × PB ewes (100%) (P < 0.05), followed by BHD × PB (88.9%), PB × PB (83.3), WD × PB (78.6%) and Ile × PB (77.8%). There were no differences in ovulation rate attributable to type of lambing from which ewe lambs came from (P > 0.05). BHD × PB ewe lambs reached puberty at an earlier age than other in this study. KT × PB ewe lambs had the highest percentage of FCL in their first ovulation. Breed of sire Ile de France increased weight to puberty and decreased FCL at first ovulation. In conclusion, the BHD × PB ewe showed puberty at an earlier age than other genotypes, while the KT × PB had the highest percentage of functional corpus luteum in their first ovulation. Ewe lambs coming from single lambings reach puberty at a heavier weight than those coming from multiple lambings. The ovulation rate in the first ovulation of ewe lambs is not affected by genotype and type of lambing.     

Prevalence,geographic distribution and phenotypic differences of Piscirickettsia salmonis EM‐90‐like isolates

Early reports accounted for two main genotypes of Piscirickettsia salmonis, a fish pathogen and causative agent of piscirickettsiosis, placing the single isolate EM‐90 apart from the prototypic LF‐89 and related isolates. In this study, we provide evidence that, contrary to what has been supposed, the EM‐90‐like isolates are highly prevalent and disseminated across Chilean marine farms. Molecular analysis of 507 P. salmonis field isolates derived from main rearing areas, diverse hosts and collected over 6 years, revealed that nearly 50% of the entire collection were indeed typed as EM‐90‐like. Interestingly, these isolates showed a marked host preference, being recovered exclusively from Atlantic salmon (Salmo salar) samples. Although both strains produce undistinguishable pathological outcomes, differences regarding growth kinetics and susceptibility to the antibiotics and bactericidal action of serum could be identified. In sum, our results allow to conclude that the EM‐90‐like isolates represent an epidemiologically relevant group in the current situation of piscirickettsiosis. Based on the consistency between genotype and phenotype exhibited by this strain, we point out the need for genotypic studies that may be as important for the Chilean salmon industry as the continuous surveillance of antimicrobial susceptibility patterns.