RESUMO
Rhipicephalus (Boophilus) microplus is controlled almost exclusively using synthetic acaricides, and reports of resistant populations have been described worldwide. Several time-consuming and laborious toxicological in vitro tests have been used to diagnose acaricidal resistance, especially those that require differential counting of live and dead larvae. Larval mortality is currently done manually and subjectively, which can limit the performance of a large number of tests and comparing results between different laboratories. The present study aimed to develop and validate a new automatic counting method to evaluate tick larval mortality. A software for differentiation of live and dead larvae was developed using different steps: obtaining videos; image segmentation using the firefly algorithm; detection of larvae with the fast radial symmetry transform technique (FRST); and tracking of the larvae at a given time. Larval immersion tests with ivermectin, cypermethrin, and fipronil were performed to validate the developed software. The larval mortality evaluation was performed by (1) recording for 60 s for each package and (2) manual counts of the same sample using three different analysts, each responsible for counting one replicate of each test. All videos obtained were copied and cut at 60, 40, and 20 s for later analysis in the counting software. The median lethal doses (LD50) of the different compounds in each test were calculated for each method (automatic and manual) for different video times. There was no statistical difference in LD50 between manual and automatic count techniques for ivermectin and fipronil. The LD50 of cypermethrin calculated with manual evaluation was up to 2.2 times lower than that of automatic evaluation. The acquisition time of the videos was 2.9-4.4 times faster than the manual evaluation. The average processing time for each video was 5.73 min, regardless of their duration. Thus, the method developed for automatic counting of tick larvae was validated, and although it still has points to be optimized, it can be considered a viable alternative for determining the percentage of tick larvae mortality and could be applied to toxicological in vitro tests with acaricides, assisting in the diagnosis of resistant tick populations and studies of novel acaricide development.
Assuntos
Acaricidas , Doenças dos Bovinos , Rhipicephalus , Infestações por Carrapato , Acaricidas/farmacologia , Animais , Bovinos , Resistência a Inseticidas , Larva , Software , Infestações por Carrapato/veterináriaRESUMO
Objetivos: Valorar la precisión de la determinación ecográfíca del sexo fetal entre las 11 y las 14 semanas en una cohorte no seleccionada de gestantes. Métodos: Se realizó un estudio prospectivo transversal en una serie consecutiva de 636 gestaciones entre las 11 y 14 semanas, en gestantes que acudieron para el estudio ecográfco rutinario de primer trimestre. Se examinó la región genital del feto en un plano mediosagi-tal, visualizando el signo sagital y la dirección en la que apunta el tubérculo genital (craneal en los varones, caudal en las mujeres) ambos indicadores del sexo fetal. La confrmación clínica del sexo fetal se obtuvo después del parto por confrmación telefónica, o por el cariotipo en casos con amniocentesis por indicaciones convencionales. Resultados: Se consiguió asignar el sexo fetal correctamente en el 86,3 por ciento de los fetos. La precisión de la asignación ecográfca del sexo fetal fue mayor en varones que en mujeres (el 90,6 por ciento de los varones fueron asignados correctamente vs el 83,1 por ciento de las mujeres, p<0,05), y se incrementó con la edad gestacional desde un 72 por ciento entre las 11 y 11+6 semanas, un 92 por ciento entre las 12 y las 12+6 semanas, hasta un 95 por ciento entre las 13 y las 13+6 semanas. Conclusión: La determinación ecográfíca del sexo fetal tiene una elevada tasa de precisión a partir de las 13 semanas, lo que sugiere que las pruebas invasivas para la exclusión de enfermedades ligadas al X podrían obviarse cuando se identifca un feto varón a esta edad gestacional. Sin embargo, en fetos identifcados como mujeres esta decisión deberá posponerse hasta una edad gestacional más avanzada.
Objective: To assess the accuracy of fetal gender determination by ultrasound at 11-14 weeks of gestation in a large cohort of unselected population. Methods: A prospective cross-sectional study was performed in 636 consecutive pregnancies at 11-14 weeks of gestation, attending for frst trimester ultrasound screening. The genital region was examined in the mid-sagittal plane to detect the sagittal sign and the direction in which the genital tubercle pointed (cranial for males, caudal for females) both as markers of fetal gender. The clinical confrmation of fetal gender was obtained from telephonic interviews after delivery or from karyotype in cases scheduled to amniocentesis for conventional indications. Results: Fetal gender was correctly determined by ultrasound in 86.3 percent of the fetuses. The accuracy of sex assignment was higher in male fetuses than in female fetuses (90.6 percent of the males fetuses vs 83.1 percent of the females were correctly assigned, p<0.05) and increased with gestational age from 72 percent at 11-11+6 week's to 92 percent at 12-12+6 week's, and 95 percent at 13-13+6 week's gestation (p<0.01). Conclusion: Prenatal gender assignment by ultrasound has a high accuracy rate at 13 to 13+6 weeks. These results suggest that invasive testing can probably be performed in fetuses identifed as males at this gestational age. However in fetuses identifed as females, the decision regarding invasive testing should be postponed until a higher gestational age is achieved.