Current status of resistance to ivermectin in Rhipicephalus sanguineus sensu stricto infesting dogs in three provinces in Argentina.

Intensive use of macrocyclic lactones for parasite control exerts strong selective pressure for arthropods such as ticks to become resistant to them. Rhipicephalus sanguineus sensu stricto is a tick and disease vector of significant public health and veterinary importance worldwide. We assessed the toxicological response to the macrocyclic lactone ivermectin (IVM) in R. sanguineus s.s. infesting dogs in Argentina. Samples of nine tick populations were obtained by inspecting dogs at veterinary clinics, hospitals, or rural areas in the provinces of San Luis, Rio Negro, and Buenos Aires. Pet owners were interviewed to gather data on the history of dog treatment with ectoparasiticides. The larval immersion test was used to assess the toxicological response of R. sanguineus s.s. to IVM. Dose-response mortality regressions, lethal concentrations (LC), and slope were calculated by probit analysis. The lowest LC concentrations were used to designate the reference susceptible population because a laboratory reference strain of R. sanguineus s.s. does not exist in Argentina. Compared with the most susceptible tick population in this study, six populations (66.66%) were classified as resistant to IVM. A clear interpopulation variation in the level of IVM resistance was present (resistance ratios at LC50% ranged from 1.0 to 18.33 and at LC99% ranged from 1.0 to 8.96). In San Luis Province, all tick populations were classified as resistant. The highest level of IVM resistance (resistance ratio at LC50%:18.83 and LC99%:8.96) was found in a population of R. sanguineus s.s. from a rural area in the province of Buenos Aires. It is concluded that populations of R. sanguineus s.s. from dogs in three provinces of Argentina were resistant to IVM. Clear interpopulation variation in the level of IVM resistance was present.

Nicotina en leche materna y sus consecuencias en los lactantes / Nicotine in mother’s milk and its consequences in breastfeeding infants

El tabaquismo, principal causa de muerte prevenible, es una pandemia cuya prevalencia en mujeres ha aumentado en las últimas décadas. Este trabajo pretende exponer los principales efectos de la nicotina en el lactante y su influencia en la composición de la leche materna. La lactancia materna exclusiva durante los primeros 6 meses de vida es la alimentación ideal para el desarrollo del neonato, por lo que su pureza debe ser conservada. La nicotina pasa a la leche materna, exponiendo a los lactantes a posibles efectos tóxicos: mayor riesgo de infecciones, cólicos, irritabilidad, síndrome de muerte súbita del lactante y síndrome de abstinencia. El tabaquismo disminuye el volumen de leche producido y altera la composición de ésta, disminuyendo su contenido de yodo, vitaminas y de grasas e incrementando los niveles de compuestos policíclicos aromáticos.El análisis fisiopatológico, clínico y socioeconómico de la problemática es complejo, por lo que es necesario generar alianzas interdisciplinarias para afrontarla...