Preliminary studies indicated that single-dose (500 mg) mebendazole gave disappointing results in the treat ment of hookworm infections (Necator americanus) in Mali. A placebo-controlled, randomized trial conducted with the participation of 103 infected subjects (background hookworm prevalence > 50%) confirmed that mebendazole (Vermox®) did not reduce parasite burdens significanfly, as assessed through fecal egg counts. In contrast, a group of subjects treated with pyrantel (Combantrin®) experienced a significant reduction in fecal worm egg counts (overall, both sexes combined showed a 75% reduction). Male subjects carried significantly more intense infections compared with females, but there was no gender difference in response to treatment. A standard egg hatch assay showed that N. americanus from our subjects in Mali was more resistant to benzimidazoles compared with a laboratory-maintained strain that had not been exposed to anthelmintics in more than 100 generations (50% effective dose = 0.12 and 0.07 p.g/ml of thiabendazole, DE CLERCQ AND OTHERSruniversitaire Raad (Flemish Inter University Council), Brussels, Belgium.

Background: In humans, atrial fibrillation (AF) induces electrical, contractile, and structural remodeling leading to AF stabilization. Little is known about AF-induced atrial remodeling in horses.Hypothesis: Induced AF produces rapid atrial electrical and contractile remodeling in horses. Animals: Six horses, 5 animals completed the study. Methods: Each horse was instrumented with a pulse generator and pacemaker to maintain AF by burst pacing and to study atrial and ventricular electrophysiology (AF cycle length [AFCL], AF duration, and atrial/ventricular effective refractory period [AERP/VERP] at different pacing cycle lengths [PCL]). Left atrial and ventricular contractile remodeling were assessed echocardiographically by calculation of fractional changes in atrial and ventricular dimensions, respectively, during the cardiac cycle. Measurements were performed at baseline, a 7-day AF period and a 2-day recovery period.Results: Atrial electrical and contractile remodeling could be demonstrated after 4 and 12 hours of AF, respectively. A progressive shortening of the AERP (261 AE 39-171 AE 18 ms at a PCL of 1,000 ms, P o .0001), an attenuation of the AERP rate adaptation, a decrease in AFCL (239 AE 39-194 AE 7 ms, P o .0001), and a decrease in atrial FS (12 AE 3% to 0 AE 2%, P o .05) occurred. AF duration increased progressively and became persistent in 2 animals. VERP did not change significantly. Upon restoration of sinus rhythm, values returned to baseline within 48 hours.Conclusions and Clinical Importance: Atrial electrical and contractile remodeling appears rapidly. After 7 days of AF, reverse remodeling occurred within 2 days. These observations suggest that early conversion of AF might be beneficial for success rate and early return to training.

BackgroundAlthough atrial fibrillation (AF) can be successfully treated in horses, recurrence occurs frequently. In humans, atrial function after cardioversion can predict recurrence.ObjectivesTo examine the prognostic value of atrial mechanical function at 24 hours after cardioversion and other potential predictor variables for AF recurrence in horses.Animals117 horses treated for AF at 4 referral centers.MethodsRetrospective study. Inclusion criteria were successful cardioversion, echocardiography at 24 hours after cardioversion and ≥4 months follow‐up. To determine factors associated with AF recurrence, a multivariable survival model was built.Results133 AF episodes in 117 horses were included. AF recurred in 36/100 horses with a first AF episode and in 57/133 AF episodes overall. Factors associated with recurrence in horses with a first episode were previous unsuccessful treatment attempt (hazard ratio HR 2.36, 95% confidence interval CI 1.11–4.99, P = .025) and mild or moderate mitral regurgitation (HR 2.70, 95% CI 1.23–5.91, P = .013). When the last AF episode of all horses was included, previous AF (HR 2.53, 1.33–4.82, P = .005) and active left atrial fractional area change ≤9.6% (HR 3.43, 1.22–9.67, P = .020) were significant predictors.Conclusions and Clinical ImportanceThe only echocardiographic variable of left atrial function with significant prognostic value for recurrence was low active left atrial fractional area change. Further research is necessary to evaluate whether echocardiography at a later timepoint could provide more prognostic information.

Summary 10Reasons for performing the study: Atrial fibrillation (AF) is the most important dysrhythmia 11 affecting performance in horses and has been associated with incoordination, collapse and 12 sudden death. Limited information is available on ventricular response during exercise in 13 horses with lone AF. 14 Objectives: To investigate ventricular response in horses with lone AF during a standardised 15 lungeing exercise test. Results: Individual average heart rate during walk ranged from 42 to 175 bpm, during trot 21 from 89 to 207 bpm, during canter from 141 to 269 bpm, and during gallop from 191 to 311 22 bpm. Individual beat-to-beat maximal heart rate ranged from 248 to 492 bpm. Ventricular 23 premature depolarisations were present in 81% of the horses: at rest (16%), during exercise 24 (69%), and during recovery (2%). In 33% of the horses, broad QRS complexes with R-on-T 25 morphology were found. 26Conclusions: Exercising horses with lone AF frequently develop disproportionate tachycardia. 27In addition, QRS broadening and even R-on-T morphology is frequently found. QRS 28 broadening may originate from ventricular ectopic foci or from aberrant intra-ventricular 29 conduction, for example due to bundle branch block. This might explain the high number of 30 complexes currently classified as ventricular premature depolarisations. 31Potential relevance: Prevalence of QRS broadening and especially R-on-T was very high in 32 horses with AF and was found at low levels of exercise. These dysrhythmias are considered 33 risk factors for the development of ventricular tachycardia and fibrillation and they might 34 explain signs of weakness, collapse or sudden death that have been reported in horses with 35 AF. 36Accepted Article 3

SummaryIn an epidemic focus in northern Senegal, adults had lower intensities of infection than adolescents, a phenomenon that could not be attributed to immunity acquired over the previous 10-15 years of exposure to the parasite because all age groups had had the same number of years' experience of the worm. This article considers whether this pattern could have been because of higher levels of exposure to the parasite in younger age groups. Personal contact with infected water was recorded using a questionnaire in Schistosoma mansoni foci not more than 3 years old and in another, 10-year-old focus. Many aspects of contact (e.g. frequency, duration or time of day of contact) may contribute to the number of encounters with infective cercariae (true exposure), so various assumptions regarding the relationship between water contact and true exposure were tested resulting in a range of exposure indices. People reported a mean of 4.4 separate contacts, and spent a median of 57 min per day in water. Patterns of water contact differed depending on the exposure index used, e.g. considering duration, males spent a longer time in water than females (P < 0.001). But using frequency, females had more contacts with water than males in most villages (P < 0.001). Generally, exposure levels dropped as people become aged (P < 0.001) and residents of the older focus were more exposed than residents of other foci (P < 0.002). Intensity of (re)infection was not related to exposure either alone or in models incorporating age, sex and/or village irrespective of the index used. There is therefore evidence that age, sex and place of residence determine exposure but none to suggest that exposure had an influence on the relationship between these factors and intensity of infection. We propose therefore that in this population other factors have principal importance in determining intensity of infection.keywords Schistosoma mansoni, human, Senegal, water contact correspondence J. Scott,