Diagnostic applications of molecular and serological assays for bluetongue and African horse sickness.

The availability of rapid, highly sensitive and specific molecular and serologic diagnostic assays, such as competitive enzyme-linked immunosorbent assay (cELISA), has expedited the diagnosis of emerging transboundary animal diseases, including bluetongue (BT) and African horse sickness (AHS), and facilitated more thorough characterisation of their epidemiology. The development of assays based on real-time, reverse-transcription polymerase chain reaction (RT-PCR) to detect and identify the numerous serotypes of BT virus (BTV) and AHS virus (AHSV) has aided in-depth studies of the epidemiology of BTV infection in California and AHSV infection in South Africa. The subsequent evaluation of pan-serotype, real-time, RT-PCR-positive samples through the use of serotype-specific RT-PCR assays allows the rapid identification of virus serotypes, reducing the need for expensive and time-consuming conventional methods, such as virus isolation and serotype-specific virus neutralisation assays. These molecular assays and cELISA platforms provide tools that have enhanced epidemiologic surveillance strategies and improved our understanding of potentially altered Culicoides midge behaviour when infected with BTV. They have also supported the detection of subclinical AHSV infection of vaccinated horses in South Africa. Moreover, in conjunction with whole genome sequence analysis, these tests have clarified that the mechanism behind recent outbreaks of AHS in the AHS-controlled area of South Africa was the result of the reversion to virulence and/or genome reassortment of live attenuated vaccine viruses. This review focuses on the use of contemporary molecular diagnostic assays in the context of recent epidemiologic studies and explores their advantages over historic virus isolation and serologic techniques.

La disponibilité d'essais diagnostiques moléculaires et sérologiques rapides, hautement sensibles et spécifiques tels que l'épreuve immuno-enzymatique de compétition (ELISAc), a accéléré le diagnostic des maladies animales transfrontalières émergentes, dont la fièvre catarrhale ovine (FCO) et la peste équine, et contribué à dresser un tableau épidémiologique plus complet de ces maladies. Grâce à la mise au point d'essais basés sur l'amplification en chaîne par polymérase en temps réel couplée à une transcription inverse (RT­PCR) qui permettent de détecter et d'identifier les nombreux sérotypes du virus de la fièvre catarrhale du mouton et du virus de la peste équine, des études approfondies ont pu être conduites sur l'épidémiologie de l'infection par le virus de la fièvre catarrhale du mouton en Californie et de l'infection par le virus de la peste équine en Afrique du Sud. L'évaluation postérieure des échantillons positifs à une RT­PCR en temps réel de groupe (détectant le virus quel que soit le sérotype) au moyen de RT­PCR spécifiques de chaque sérotype permet d'identifier rapidement le sérotype causal et de limiter le recours à des méthodes classiques onéreuses et chronophages comme l'isolement viral ou les essais de neutralisation virale spécifiques de chaque sérotype. Les outils fournis par ces essais moléculaires et par les plateformes ELISAc ont renforcé les stratégies de surveillance épidémiologique et permis de mieux connaître les altérations potentielles de comportement chez les tiques Culicoides infectées par le virus de la fièvre catarrhale du mouton. Ils ont également contribué à détecter les cas d'infection asymptomatique par le virus de la peste équine chez des chevaux vaccinés en Afrique du Sud. En outre, associés avec l'analyse de séquences du génome entier, ces tests ont révélé que le mécanisme sous-jacent aux récents foyers de peste équine dans la zone de contrôle en Afrique du Sud correspondait à une réversion vers la virulence et/ou à un réassortiment du génome des souches de vaccin à virus vivant atténué. Les auteurs passent en revue l'utilisation des essais de diagnostic moléculaire de nouvelle génération dans le contexte de récentes études épidémiologiques et cherchent à établir leurs avantages par rapport aux techniques classiques d'isolement viral et de recherche sérologique.

La existencia de ensayos moleculares y serológicos de diagnóstico rápidos y de gran sensibilidad y especificidad, como el ensayo inmunoenzimático de competición (ELISAc), ha acelerado el diagnóstico de enfermedades animales transfronterizas emergentes, como la lengua azul o la peste equina, y facilitado una caracterización más exhaustiva de su epidemiología. La creación de ensayos basados en la reacción en cadena de la polimerasa acoplada a transcripción inversa (RT?PCR) en tiempo real para detectar y caracterizar los numerosos serotipos de los virus de la lengua azul y la peste equina ha ayudado a estudiar a fondo la epidemiología de sendos episodios infecciosos causados por el virus de la lengua azul en California y por el virus de la peste equina en Sudáfrica. El subsiguiente análisis de las muestras positivas a la prueba de RT?PC en tiempo real de cualquier serotipo con empleo de ensayos RT?PCR dirigidos específicamente contra uno u otro serotipo permite identificar rápidamente los serotipos víricos, lo que hace menos necesario el uso de métodos convencionales más caros y largos, como el aislamiento del virus o técnicas de neutralización vírica adaptadas específicamente a un serotipo. Estos dispositivos de ensayo molecular o de ELISAc ponen a nuestra disposición herramientas que potencian las estrategias de vigilancia epidemiológica y ayudan a conocer mejor las eventuales alteraciones del comportamiento de los jejenes Culicoides al ser infectados por el virus de la lengua azul. Estas técnicas han ayudado también a detectar en Sudáfrica casos de infección asintomática por el virus de la peste equina en caballos vacunados. Estas pruebas, además, empleadas en combinación con el análisis de secuencias genómicas completas, han servido para aclarar que el mecanismo subyacente a los recientes brotes de peste equina surgidos en la zona de Sudáfrica donde la enfermedad estaba bajo control fue fruto de la reversión a la virulencia y/o el reordenamiento genómico de virus vacunales atenuados. Los autores, centrándose en el uso de modernos ensayos moleculares de diagnóstico como parte de recientes estudios epidemiológicos, examinan las ventajas que ofrecen en comparación con las tradicionales técnicas serológicas y de aislamiento vírico.

Predictors of foaling outcomes in barren and maiden Thoroughbred mares in South Africa.

Population demographics and reproductive performance of Thoroughbred populations have been described, but the most recent assessment of the South African Thoroughbred population was reported two decades ago. Objectives of this study were to report demographic data for selected Thoroughbred breeding populations and to analyse selected mare-level variables in association with foaling outcomes, as predictors of reproductive performance. The National Horseracing Authority of Southern Africa's stud health scheme requires annual screening of Thoroughbred stallions, maiden and barren mares for venereal pathogens prior to breeding. In 2018 and 2019, 1 065 and 1 207 horses were sampled, respectively. Demographic data were sourced from laboratory sample submission forms that accompanied samples and supplemented by data gathered from the annual Thoroughbred foal identification programme. Univariate analysis of candidate predictors of successful foaling outcomes was performed followed by assessment in a multivariable model.Median ages of mares and stallions tested in 2018 and 2019 were nine and 11 years, respectively. Nearly twice the number of barren compared to maiden mares were tested in each year, and failure to conceive was the most common reported reason for classification as barren. Of mares tested in 2018 and 2019, 68.1% (95% CI 65.1, 70.9) and 63.3% (95% CI 60.4, 66.1), respectively, subsequently produced foals that were presented for identification. Mare age, rather than reproductive status, was a significant predictor of having a foal presented for identification. In conclusion, novel demographic data were described for South African Thoroughbred populations. Seasonal foaling rate as the selected measure of reproductive performance for sampled mares ranged from 63.3% to 68.1% and declined with increasing mare age.

Outcomes of intensive surveillance after resection of hepatic colorectal metastases.

BACKGROUND: The impact of computed tomography (CT)-based follow-up for the detection of resectable disease recurrence following surgery for colorectal liver metastases (CRLM) was evaluated. METHODS: Some 705 patients undergoing resection of CRLM between January 1993 and March 2007 were included. Surveillance comprised 3-monthly CT (thorax, abdomen and pelvis) in the first 2 years after surgery, 6 monthly for 3 years and annually from years 6 to 10. Survival differences following recurrence between patients managed surgically and palliatively were determined, and the cost was calculated. RESULTS: Five-year disease-free and overall survival rates were 28.3 and 32.3 per cent respectively. Of 402 patients who developed recurrence within 2 years, 88 were treated with liver resection alone and 36 with lung and/or liver resection. Their 5-year overall survival rates were 31 and 30 per cent respectively, compared with 3.9 per cent in 278 patients managed palliatively (P < 0.001). For each 3-month interval during the first year of follow-up, patients with recurrence treated surgically had better overall survival than those treated palliatively. The cost of surveillance that identified 124 patients amenable to further resection was 12,338 pounds per operated recurrence. Assuming that patients with recurrence gained 5 years' survival, the mean survival gain was 4.28 years per resection and the cost per life-year gained was 2883 pounds. CONCLUSION: Intensive 3-monthly CT surveillance after liver resection for CRLM detects recurrence that is amenable to further resection in a considerable number of patients. These patients have significantly better survival with a reasonable cost per life-year gained.

Duration of repellency of N,N-diethyl-3-methylbenzamide, citronella oil and cypermethrin against Culicoides species when applied to polyester mesh.

The repellent efficacy of 15% N,N-diethyl-3-methylbenzamide (DEET), 0.6% citronella oil, and 0.3% alpha-cyano-cypermethrin against Culicoides species was compared in three 5x5 Latin squares (15 replicates) under South African field conditions. DEET, citronella oil or alpha-cyano-cypermethrin were applied to polyester meshes that were fitted to down-draught suction 220V UV light traps which were operated overnight. No significant repellent effect against Culicoides was found for the citronella oil or the alpha-cyano-cypermethrin. DEET had a significant repellent effect against Culicoides species and C. imicola for all catches made from after sunset to before sunrise.

Annual ryegrass toxicity in Thoroughbred horses in Ceres in the Western Cape Province, South Africa.

An outbreak of annual ryegrass toxicity occurred on a Thoroughbred stud in Ceres in the Western Cape Province of South Africa. This is the 1st report of annual ryegrass toxicity in horses in South Africa, although the condition has been reported in cattle and sheep populations in the past. Annual ryegrass toxicity is characterised by a variety of neurological signs including tremors, convulsions, recumbency and in many cases death. The description of the outbreak includes the history, clinical presentation and treatment protocol administered during the outbreak. Various epidemiological variables and their influence in the outbreak are also considered.

Prevalence of serotype specific antibody to equine encephalosis virus in Thoroughbred yearlings in South Africa (1999-2004).

Cohorts of yearlings were sampled over a period of 6 years in a retrospective serological survey to establish the annual prevalence of serotype specific antibody to equine encephalosis virus on Thoroughbred stud farms distributed within defined geographical regions of South Africa. Seasonal seroprevalence varied between 3.6% and 34.7%, revealing both single and multiple serotype infections in an individual yearling. During the course of this study serotypes 1 and 6 were most frequently and extensively identified while the remaining serotypes 2, 3, 4, 5 and 7 were all identified as sporadic and localized infections affecting only individual horses. This study of the seasonal prevalence of equine encephalosis virus has a corollary and serves as a useful model in the seasonal incidence of the serotypes of African horse sickness and bluetongue in regions where the respective diseases are endemic.

Dynamics of African horse sickness virus nucleic acid and antibody in horses following immunization with a commercial polyvalent live attenuated vaccine.

African horse sickness (AHS) is a fatal disease of equids relevant to the global equine industry. Detection of AHS virus (AHSV) during outbreaks has become more rapid and efficient with the advent of group specific reverse transcriptase quantitative polymerase chain reaction (GS RT-qPCR) assays to detect AHSV nucleic acid. Use of GS RT-qPCR together with recently described type specific (TS RT-qPCR) assays cannot only expedite diagnosis of AHS but also facilitate further evaluation of the dynamics of AHSV infection in the equine host. A potential limitation to the application of these assays is that they detect viral nucleic acid originating from any AHS live attenuated vaccine (LAV), which is the vaccine type routinely administered to horses in South Africa. The aim of this study was to contrast the dynamics and duration of the RNAaemia to the serological responses of horses following immunization with a commercial polyvalent AHSV-LAV using GS and TS RT-qPCR assays and serum neutralisation tests. The results of the study showed extended RNAemia in vaccinated horses, and that more horses tested positive on GS RT-qPCR with lower Cq values after receiving the AHSV-LAV containing types 1, 3 and 4 prior to the vaccine containing types 2, 6, 7 and 8, rather than when the vaccine combinations were reversed. Furthermore, lower Cq values were obtained when vaccines were administered 4weeks apart as compared with a longer interval or 12weeks apart. These findings are of particular relevance in regions where AHSV-LAVs are used as the use of these vaccines may complicate the accurate interpretation of diagnostic testing results.

Polymerase chain reaction-based national surveillance programme to determine the distribution and prevalence of Taylorella equigenitalis in South African horses.

REASONS FOR PERFORMING STUDY: The response to the first outbreak of contagious equine metritis in South Africa included pioneering a web-based platform to coordinate key aspects of a national, real-time polymerase chain reaction (qPCR)-based stallion screening programme to determine the distribution and prevalence of Taylorella equigenitalis in stallions and exposed mares. OBJECTIVES: To define the hypothesised pre-existing status of T. equigenitalis in the South African equine population and progression of the epidemiological investigation via the implementation of a molecular diagnostic-based surveillance programme. STUDY DESIGN: Retrospective case series. METHODS: Screening for T. equigenitalis was via a qPCR assay on genital swabs obtained from predilection sites in stallions and mares with subsequent confirmation using bacterial culture according to prescribed methods. RESULTS: The initial outbreak investigation identified 4 horses including the index stallion and mare. Traceback of in-contact horses identified 26 horses, including a subpopulation focus at the South African Lipizzaner Centre where 24/33 resident stallions tested positive for T. equigenitalis on qPCR. The national screening programme identified an additional 9 stallions. A total of 39 horses (36 stallions and 3 mares) tested positive for T. equigenitalis by qPCR and T. equigenitalis was isolated from 23 of these stallions and 2 of these mares. In addition to the index property, an artificial breeding centre where the index case was first identified, an additional 12 properties with infected horses were identified in 3/9 provinces. Horses on 11 of these 12 properties were directly linked to the index property. Two incidents of T. equigenitalis transmission associated with artificial insemination were recorded. CONCLUSIONS: T. equigenitalis was present in a subpopulation focus within the South African horse population prior to the outbreak identification in April 2011. Horizontal fomite-associated spread was the most probable route of transmission between stallions. The targeted surveillance of stallions and exposed mares using a qPCR-based screening programme expedited investigation of the distribution and prevalence of T. equigenitalis infection in South African horses. The application of qPCR provided a sensitive and practical screening test for identification of T. equigenitalis-positive animals as part of an emergency response to the first identified cases of T. equigenitalis infection in South African horses.

Clinical and clinicopathological changes in 6 healthy ponies following intramuscular administration of multiple doses of imidocarb dipropionate.

Haematological variables and selected serum indices, particularly those affected by changes in renal and hepatic function, were examined in 6 healthy ponies following 4 intramuscular doses of 4 mg/kg imidocarb dipropionate administered every 72 hours. This treatment regime has been reported to sterilise experimental Babesia equi infections in horses and may have value in preventing the spread of this disease during exportation of possible carrier horses to non-endemic countries. Serum bile acids and serum gamma glutamyltransferase activity were measured to evaluate the effect of this treatment regime on hepatic function. Owing to the absence of any increase in these variables it was concluded that this treatment regime had no clinically detectable deleterious effect on hepatic function in healthy ponies. Urinary gamma glutamyltransferase : creatinine ratios (IU/g), serum creatinine and fractional clearance of sodium, potassium and phosphate (%) were calculated as a measure of renal function. Urinary GGT and urinary GGT : creatinine ratios were significantly elevated on Day 5 of the trial, with 2 of the trial animals also exhibiting mild azotaemia indicative of changes in renal function. The changes in urine GGT : urine creatinine ratios observed in this study also provides evidence of the value of this ratio for the early detection of renal toxicity, following exposure to nephrotoxic agents.

Exercise-induced pulmonary haemorrhage impairs racing performance in Thoroughbred racehorses.

REASONS FOR PERFORMING STUDY: Exercise-induced pulmonary haemorrhage (EIPH) occurs commonly in Thoroughbred racehorses worldwide. While EIPH is believed to be an important cause of impaired performance in these horses, there is limited evidence from sufficiently powered studies to evaluate this association. OBJECTIVES: To evaluate whether EIPH is associated with finishing position, distance finished behind race winners and differences in race earning among Thoroughbred horses racing in South Africa. STUDY DESIGN: Prospective cross-sectional study. METHODS: One thousand Thoroughbred horses racing in South Africa were enrolled prior to a single race and underwent tracheobronchoscopic examination within 2 h of racing. Three observers, blinded to the horses' identity and race performance, independently evaluated EIPH occurrence and severity using video recordings of the examination. Data were analysed using multivariable logistic and linear regression while controlling for important horse and race factors as potential confounding variables. RESULTS: Overall, 68% of horses had evidence of EIPH (grade ≥1). Horses without evidence of EIPH (severity grade 0), when compared with horses with any evidence of EIPH (grade ≥1), were >2 times more likely to win races (odds ratio = 2.3; 95% confidence interval 1.4-3.7; P = 0.001), finished an average of one length ahead of horses with EIPH (P = 0.03), and were 2.5 times more likely to be in the highest decile in race earnings (odds ratio = 2.5, 95% CI 1.5-4.1, P<0.001). However, no association was identified regarding finishing in the top 3 positions or earning money when analysed as a continuous variable or analysed as any winnings vs. none. CONCLUSIONS: Exercise-induced pulmonary haemorrhage was associated with impaired performance in Thoroughbred racehorses not medicated with furosemide and not using nasal dilator strips. These findings provide strong corroboration of previous research indicating that the occurrence of EIPH has a major impact on the ability of Thoroughbred racehorses to compete successfully as elite athletes.

Efficacy of alphacypermethrin-treated high density polyethylene mesh applied to jet stalls housing horses against Culicoides biting midges in South Africa.

The efficacy of alphacypermethrin-treated high density polyethylene (HDPE) mesh applied to jet stalls against Culicoides biting midges (Diptera: Ceratopogonidae) was determined by mechanical aspiration of midges from horses and using Onderstepoort 220 V downdraught black light traps in four blocks of a 3 × 2 randomised design under South African field conditions. The alphacypermethrin-treated HDPE mesh applied to the stall significantly (P = 0.008) reduced the number of Culicoides midges, predominantly Culicoides (Avaritia) imicola Kieffer, mechanically aspirated from horses housed in the stall. The mesh reduced the Culicoides midge attack rate in the treated stall compared to the untreated stall and a sentinel horse by 6 times and 14 times, respectively. The number of Culicoides midges and C. imicola collected in light traps from the untreated and alphacypermethrin HDPE mesh-treated stalls did not differ significantly (P = 0.82). Alphacypermethrin-treated HDPE mesh could be used to reduce exposure of horses in jet stalls to Culicoides midges, specifically C. imicola, and the risk of midge-borne Orbivirus transmission.

Epidemiology and reproductive outcomes of EHV-1 abortion epizootics in unvaccinated Thoroughbred mares in South Africa.

REASONS FOR PERFORMING STUDY: Equine herpesvirus 1 (EHV-1) is one of the most common causes of infectious abortion in mares. Analysing the demography of outbreaks and detailing subsequent reproductive performance of affected mares will assist in the management of future (threatened) epizootics. OBJECTIVES: To examine the epidemiology and reproductive outcomes of 2 EHV-1 abortion epizootics with very different patterns of morbidity. STUDY DESIGN: Epidemiological and reproductive data were analysed retrospectively following abortion epizootics associated with EHV-1, but initiated via different routes, among unvaccinated mares on 2 Thoroughbred farms in South Africa. METHODS: Aborting mares were assigned to either the EHV-1 abortion cohort via positive immunostaining (Farms 1 and 2) or quantitative PCR (Farm 2) on tissue samples, or to the non-EHV abortion cohort. RESULTS: During their respective epizootics, EHV-1 abortions affected 9/30 (30.0%) and 18/316 (5.7%) of the pregnant mares on Farms 1 and 2, respectively; there were also 25 (7.9%) non-EHV abortions on Farm 2. Epizootic differences included: durations (Farm 1 = 135 days; Farm 2 = 34 days), intervals between first and subsequent abortions (Farm 1 = 39 days; Farm 2 = 2 days) and intervals to confirmation of EHV-1 (Farm 1 = 40 days; Farm 2 = 2 days). The median (range) age of EHV-1 abortion mares (8.0; 5-18 years) in both epizootics was similar but significantly younger (P = 0.004) than the 25 non-EHV-1 abortion mares (11.0; 4-24 years) on Farm 2. Gestation stage (median; range) of EHV-1 (291.5; 277-313) and non-EHV-1 (211.9; 61-339 days) abortions were significantly different (P = 0.001). The post abortion complications and subsequent reproductive outcomes had no significant association with EHV-1 abortion. CONCLUSIONS: The marked difference in morbidity between the 2 epizootics may be associated with routes of introduction or intervention strategy dictated by availability of molecular diagnostic techniques. Unexpectedly, EHV-1 was not more commonly associated with post abortion complications.

Administration of bovine, porcine and equine growth hormone to the horse: effect on insulin-like growth factor-I and selected IGF binding proteins.

This study investigated the biochemical effects of administration of three types of recombinant growth hormone (GH; somatotropin) to the Thoroughbred horse. Equine or bovine or porcine GH was administered at a recommended dosage to 3-5-year old Thoroughbred geldings, for up to 21 days. It was shown that, in addition to equine GH, bovine and porcine GH were active in the horse; however, porcine GH caused injection-site reactions that were so serious that administration had to be terminated. The concentrations of a range of GH-related serum protein markers were determined before, during and after the administration period. Because of the short half-life of GH itself, the objective was to identify GH-related markers that showed changes in concentration and which could be used as indicators of the abuse of these hormones. Among the possible markers identified, serum total insulin-like growth factor (IGF)-I was shown to be the most promising, increasing to 270% of the basal concentration for equine GH administration. After GH administration, IGF-I took longer to attain baseline concentrations than the time required for GH concentrations to recover to normal. The concentration obtained from the administration significantly exceeded natural concentrations for IGF-I, as was determined from a population of more than 2000 Thoroughbred horses in three continents. The concentrations of serum free IGF-I and IGF binding protein 3 (IGFBP-3) were also shown to be significantly affected by equine and bovine GH.

Characterization of a density-corrected ultrasonic pneumotachometer for horses.

A density-corrected ultrasonic pneumotachometer designed specifically for horses (UF202) was evaluated and characterized with the aid of a custom-built apparatus. UF202 provided voltage outputs for airflow through and gas density within the flowhead. Baseline stability for flow channel output (VUF202) was < 0.35% full scale (FS), and VUF202 was linear over a range of +/- 50 l/s (R2 > or = 0.9976). Under optimal conditions, VUF202 accuracy was determined to be +/- 1.00% FS and repeatability was +/- 0.78% FS. VUF202 resolution was 24 ml/s. The rise time for VUF202 was 18 ms, and the -3-dB point was 18 Hz; digital compensation provided a flat frequency response to 32 Hz. VUF202 gain appeared to be stable over a period of 8 days. Density channel output (PUF202) was linear over a range of 1.11-1.23 g/l (R2 > or = 0.9645). PUF202 accuracy was calculated to be +/- 0.50% FS, and PUF202 repeatability was determined to be +/- 0.30% FS. Resistance of the flowhead was determined to be 0.013 cmH2O.l-1.s at a flow of 40 l/s. On the basis of this study, we conclude that UF202 should facilitate accurate measurement of breath-by-breath airflow of exercising horses.

Stimulation frequency-dependent nonadrenergic noncholinergic airway responses of the guinea pig.

We examined the inhibitory and excitatory components of the nonadrenergic noncholinergic (NANC) innervation of the guinea pig airways by in vivo and in vitro methods. Electrical stimulation of the vagus in chloralose-urethan-anesthetized guinea pigs after cholinergic and adrenergic blockade produced peripheral airway constriction (insufflation pressure) and tracheal relaxation (pouch pressure). Vagal stimulation was applied for 90 s at 5-V pulses of 2-ms duration at frequencies of 5, 15, 25, and 35 Hz in each group (n = 6). The pouch relaxation peaked at 15 Hz. The insufflation pressure was highest at 5 Hz. Field stimulations of the same frequencies were applied on tracheal spirals and lung parenchymal strips. The maximal relaxation of the trachea occurred at 15-35 Hz. The lung parenchymal strip tensions increased almost linearly as the frequency increased from 5 to 35 Hz. The results of the study indicated a frequency-dependent response for both excitatory and inhibitory components of the NANC, which operate at different frequencies for optimal responses.

Effect of three different warm-up regimens on heat balance and oxygen consumption of thoroughbred horses.

Horses were exercised at 105% of their maximal O2 uptake until fatigued after three different warm-up regimens (no warm-up, a light warm-up, and a warm-up until the central venous temperature was > 39.5 degrees C) to assess the effect of the warm-up on the various avenues of heat loss. Approximately 12.79, 15.10, and 18.40 MJ of heat were generated in response to the warm-up and exercise after the three different warm-up regimens, respectively. Of the heat generated, 17.5, 17.2, and 17.4% remained as stored heat after 20 min of active recovery. Heat loss from the respiratory system was 63.6, 33.7, and 40.3% of the heat produced during and after the three warm-up intensities, respectively. The balance of the heat loss was assumed to be via the evaporation of sweat. On this basis, the heat loss by sweating was 14.9, 49.1, and 42.3% of the heat produced during and after the three warm-up intensities, which represented evaporation of 0.8, 3.1, and 3.0 liters of sweat, respectively. O2 consumption during exercise and heart rates 20 min postexercise, after two of the warm-up regimens, was significantly lower than that after no prior warm-up.

A group-specific, indirect sandwich ELISA for the detection of equine encephalosis virus antigen.

A polyclonal antibody-based, group-specific, indirect, sandwich ELISA (S-ELISA) for the detection of equine encephalosis virus (EEV) antigen was developed. Purified EEV particles were titrated in the S-ELISA and the limit of detection was determined to be approximately 9.0 ng of antigen/ml (0.45 ng/well). Positive S-ELISA reactions were recorded with seven serologically distinct EEV serotypes. No cross-reactions were recorded with other arboviruses including African horse sickness virus (AHSV) serotypes 1-9, bluetongue serotypes 1-24, epizootic haemorrhagic disease serotypes 1-8 and isolate 318, and selected isolates of Palyam, Eubenangee, Corriparta, Warrego, Akabane and bovine ephemeral fever viruses. The assay proved to be sensitive and specific for the rapid detection of EEV in cell cultures and in homogenated suckling mouse brain (MB). The data generated in this study suggest that the ELISA will be valuable for epidemiological studies of EE and will assist in making a reliable differential diagnosis between EEV and AHSV infections.

Solid-state instrumentation for use with optical-fibre chemical-sensors.

A solid-state instrument has been developed for use with optical-fibre pH-sensors, which incorporates light-emitting diode sources and a photodiode detector. The instrument has an internal reference. The optical and electronic principles are described. The responses of the sensor and instrument are reported and compared with those obtained with conventional instrumentation.

Alternative approaches to control of cyathostomes: an African perspective.

Cyathostomes are common nematode parasites of horses, donkeys and mules in developing countries. These equids usually work on a daily basis and this includes transportation of goods, crops and people. Stress, associated with work, and limited nutrition often result in a loss of condition, and cyathostomid nematodes may, then, cause clinical disease. Because anthelmintics are not always accessible or affordable in many parts of Africa, or there may be anthelmintic resistance to current remedies, management practices are often used as an adjunct to chemotherapy. This paper discusses some current approaches to the control of cyathostomes in developing countries in Africa, as well as proposed areas of research which are practical and appropriate to this problem.

Helminth levels of working donkeys kept under different management systems in the Moretele 1 district of the North-West Province, South Africa.

In Southern Africa, where 150,000 working donkeys provide an important alternative to mechanisation in resource-poor communities, very little is known about their helminth status, or about the impact of helminths on their work output. The aim of this study was to investigate the helminth status of working donkeys under different management systems. Donkey owners in three different areas (one rural and two semi-rural) of the Moretele 1 district of North-West Province, South Africa, were visited and structured interviews were used to assess the management systems under which the donkeys were kept. Faecal samples were collected from 93 donkeys in the study once a month for 14 months. Faecal samples were analysed for nematode and trematode eggs and cultured to produce third-stage larvae for the identification of the nematode species. Final comparisons between management system subgroups, as well as between areas, age groups and sexes were made. Four management systems were identified. (1) The first system identified consisted of donkeys which were kept in a small yard at all times. They were fed hay but no supplementary food. (2) The second system consisted of donkeys which were allowed to roam freely around the village most of the time and rounded up and held in an enclosure when needed for work. (3) The third system was identical to the second management system except that the donkeys were given supplementary food during winter. (4) The fourth system was only found in the one area where each owner owned 10 ha of land and here the donkeys were allowed to roam freely on the owner's land and brought into enclosures prior to working. Helminth species composition and faecal egg count numbers differed between these four systems. The main difference noted was that donkeys from management system one showed significantly higher numbers of strongyle eggs and higher percentages of some of the strongyle larvae. Management system two had a higher Strongyloides mean egg count and prevalence than the other areas. Parascaris and Gastrodiscus egg counts differed between all four systems. Since the results showed differences in the number and species of helminths in donkeys kept under the four management systems, suggestions are made as to which management system would facilitate reduction of helminth parasites in the animals. Although supplementary feeding in Moretele 1 is fairly rare, it would seem that donkeys which do have access to better food resources have lower egg counts than donkeys on limited grazing.