Molecular survey of pyrethroid and fipronil resistance in isolates of Rhipicephalus microplus in the north of Uruguay.

The resistance of Rhipicephalus microplus to acaricides is a serious control problem, so its early diagnosis by a molecular technique is important. This study aims to develop a multiplex allele-specific polymerase chain reaction (PCR) for single-nucleotide polymorphisms (SNPs) in the para-sodium channel gene and in the GABA-Cl gene, associated with pyrethroids (cypermethrin and flumethrin) and fipronil resistance, respectively. We used 22 tick field isolates from farms with tick control problems (sampling convenience). These farms are located in departments of northern Uruguay. Three mutations in the sodium channel gene (Domain II S4-5: C190A and G215T; domain III S6: T2134A) and one in the GABA-Cl gene (A286S/L: CG856CC/TG) were studied. Mutations G215T and T213A were not detected. In all field isolates, the resistant allele (R) for C190A mutation (knockdown resistance, kdr) was detected, mainly in heterozygous individuals (SR) (11.1% to 86.7%). The highest incidence of the kdr mutant allele occurred in the Tacuarembó tick field isolates, where on 7 out of 10 farms >30% of individuals were SR and on one farm > 30% of individuals were RR. The next highest was Artigas (half of farms had>30% SR individuals and a quarter had >30% RR individuals). The resistance to dieldrin locus (rdl) mutation (CG856CC/TG) was absent in five field isolates. The highest incidenceof the mutant allele was observed in ticks from farms in Rivera (all farms had SR in >30% of individuals and two farms had RR in >12.5 and >16.7% of individuals) followed by farms in Tacuarembó (3 of 10 farms had >30% SR and 2 with >30% RR). Less than half of the farms had rdl in homozygous individuals. No significant association was observed between phenotypic bioassays and the rdl resistance allele. Several field isolates were phenotypically susceptible to the presence of the rdl allele. Several causes are possible (bioassay sensitivity, discriminating concentration). Individuals with simultaneous kdr and rdl mutations were present in 17 field isolates, and their frequency varied between 0.06% and 60%. Genotypic analysis shows that tick resistance to both acaricides, especially pyrethroids, is a serious problem. It is important to monitor the resistance using molecular techniques to plan efficient control measures. This is the first report describing kdr and rdl detection in R. microplus in Uruguay.

Multiplex allele-specific polymerase chain reaction to detect kdr and rdl mutations in the cattle tick Rhipicephalus microplus (Acari: Ixodidae).

The resistance of Rhipicephalus microplus to pyrethroids is widely dispersed worldwide and has been associated with several nucleotide substitutions in its target site, the para-sodium ion channel (Na-channel) gene. The resistance of the tick to fipronil has been increasing in South America, and mutations in the GABA-gated chloride channel (GABA-Cl) have been described in fipronil-resistant tick strains. We developed a multiplex allele-specific PCR (mAS-PCR) to screen for single-nucleotide polymorphisms (SNPs) associated with the resistance to pyrethroids (knockdown resistance or kdr) and fipronil (resistance to dieldrin or rdl) in susceptible tick populations from Uruguay (n = 11) and the Rio Grande do Sul state in Southern Brazil (n = 15). Toxicological in vitro assays with larvae and adults were used to confirm the resistance to cypermethrin, flumethrin, and fipronil. Three SNPs in the Na-channel gene were investigated (C190A, G215 T, and T2134A), and the mAS-PCR included the detection of an SNP (G858 T) coding a non-synonymous mutation in the GABA-Cl gene. C190A was present in all pyrethroid-resistant populations from Uruguay and Brazil, most frequently homozygous. The SNPs G215 T and T2134A were not found. Of the seventeen fipronil-resistant populations, fourteen presented at least one mutant GABA-Cl gene allele, more frequently in heterozygosis. Other mechanisms apart from target site insensitivity may be involved in fipronil resistance since in some resistant populations, the SNP G858 T was not detected. Sixteen (61,5%) of the populations presented individuals with simultaneous mutations in the Na-channel and GABA-Cl genes. This could be a significant problem for the future control of R. microplus. This study shows the wide dispersion of a pyrethroid resistance-associated SNP in high frequency in the region. Fipronil resistance mutations are also dispersed across the region and increasing.

Adolescentes Libres de Tabaco: Efectividad de una intervención educativa. Estudio antes-después controlado / Smoke-Free Adolescents: Effectiveness of an educational intervention. Controlled, before and after study

El tabaquismo es considerado la principal causa de muerte prevenible en el mundo. La mayoría de los fumadores inician esta adicción durante edades tempranas, especialmente, durante la adolescencia. El objetivo del estudio fue identificar los determinantes de consumo adolescente y evaluar el impacto de una intervención educativa en la prevalencia del tabaquismo. Métodos. Estudio antes-después controlado, realizado durante los años 2010-2012 en dos colegios secundarios de la ciudad de La Plata. En ambos, se realizó una encuesta basal seguida de dos mediciones posteriores; en uno de ellos, se implementó una intervención educativa dirigida a jóvenes de 12 y 13 años. Se utilizaron modelos de regresión múltiple para identificar las variables asociadas al tabaquismo y evaluar el impacto de la intervención. Resultados. Se incluyeron 1911 encuestas (Colegio A: 617; Colegio B: 1294). Las variables asociadas al tabaquismo adolescente fueron la tenencia de un hermano fumador (odds ratio -OR- 2,55), madre fumadora (OR 2,32), años de edad (OR 1,92) y el sexo femenino (OR 1,75). El OR ajustado por dichos determinantes para ser fumador actual en el colegio intervención versus el control fue 0,54 (intervalo de confianza -IC- del 95%: 0,35-0,83) en el primer año de seguimiento y 0,98 (IC 95%: 0,60-1,61) en el segundo año. Conclusiones. La tenencia de una madre o un hermano fumador, la edad y el sexo femenino se correlacionaron fuertemente con el consumo de cigarrillos. La intervención educativa tuvo un efecto positivo en el primer año de seguimiento, pero luego no se mantuvo.

Smoking is considered the main cause of preventable death worldwide. Most smokers start using tobacco at an early age, especially during adolescence. The objective of this study was to identify the determinants of adolescent use of tobacco and assess the impact of an educational intervention on the prevalence of smoking. Methods. Controlled, before and after study conducted between 2010 and 2012 at two secondary schools in the city of La Plata. A baseline survey was administered at both schools followed by two subsequent measurements; an educational intervention aimed at youth aged 12 and 13 years was implemented in one of the schools. Multiple regression models were used to identify the outcome measures associated with smoking and assess the impact of the intervention. Results. A total of 1911 surveys were included (school A: 617; school B: 1294). The outcome measures associated with adolescent smoking were having a sibling who smokes (odds ratio -amp;#91;OR-amp;#93;: 2.55), a mother who smokes (OR: 2.32), age (OR: 1.92), and female sex (OR: 1.75). The OR adjusted for these determinants to be a current smoker at the intervention school versus the control school was 0.54 (95% confidence interval -amp;#91;CI-amp;#93;: 0.35-0.83) in the first year of follow-up and 0.98 (95% CI: 0.60-1.61) in the second year. Conclusions. Having a mother or a sibling who smokes, age, and female sex were strongly correlated to cigarette smoking. The educational intervention had a positive effect in the first year of follow-up, which was not maintained over time.

Smoke-Free Adolescents. Effectiveness of an educational intervention. Controlled, before and after study. / Adolescentes Libres de Tabaco. Efectividad de una intervención educativa. Estudio antes-después controlado.

Smoking is considered the main cause of preventable death worldwide. Most smokers start using tobacco at an early age, especially during adolescence. The objective of this study was to identify the determinants of adolescent use of tobacco and assess the impact of an educational intervention on the prevalence of smoking. Methods. Controlled, before and after study conducted between 2010 and 2012 at two secondary schools in the city of La Plata. A baseline survey was administered at both schools followed by two subsequent measurements; an educational intervention aimed at youth aged 12 and 13 years was implemented in one of the schools. Multiple regression models were used to identify the outcome measures associated with smoking and assess the impact of the intervention. Results. A total of 1911 surveys were included (school A: 617; school B: 1294). The outcome measures associated with adolescent smoking were having a sibling who smokes (odds ratio [OR]: 2.55), a mother who smokes (OR: 2.32), age (OR: 1.92), and female sex (OR: 1.75). The OR adjusted for these determinants to be a current smoker at the intervention school versus the control school was 0.54 (95% confidence interval [CI]: 0.35-0.83) in the first year of follow-up and 0.98 (95% CI: 0.60-1.61) in the second year. Conclusions. Having a mother or a sibling who smokes, age, and female sex were strongly correlated to cigarette smoking. The educational intervention had a positive effect in the first year of follow-up, which was not maintained over time

El tabaquismo es considerado la principal causa de muerte prevenible en el mundo. La mayoría de los fumadores inician esta adicción durante edades tempranas, especialmente, durante la adolescencia. El objetivo del estudio fue identificar los determinantes de consumo adolescente y evaluar el impacto de una intervención educativa en la prevalencia del tabaquismo. Métodos. Estudio antes-después controlado, realizado durante los años 2010-2012 en dos colegios secundarios de la ciudad de La Plata. En ambos, se realizó una encuesta basal seguida de dos mediciones posteriores; en uno de ellos, se implementó una intervención educativa dirigida a jóvenes de 12 y 13 años. Se utilizaron modelos de regresión múltiple para identificar las variables asociadas al tabaquismo y evaluar el impacto de la intervención. Resultados. Se incluyeron 1911 encuestas (Colegio A: 617; Colegio B: 1294). Las variables asociadas al tabaquismo adolescente fueron la tenencia de un hermano fumador (odds ratio ­OR­ 2,55), madre fumadora (OR 2,32), años de edad (OR 1,92) y el sexo femenino (OR 1,75). El OR ajustado por dichos determinantes para ser fumador actual en el colegio intervención versus el control fue 0,54 (intervalo de confianza ­IC­ del 95%: 0,35-0,83) en el primer año de seguimiento y 0,98 (IC 95%: 0,60-1,61) en el segundo año. Conclusiones. La tenencia de una madre o un hermano fumador, la edad y el sexo femenino se correlacionaron fuertemente con el consumo de cigarrillos. La intervención educativa tuvo un efecto positivo en el primer año de seguimiento, pero luego no se mantuvo.

Efficiency of a walk-through fly trap for Haematobia irritans control in milking cows in Uruguay.

Haematobia irritans (horn fly) is a bloodsucking insect that affects grazing cattle. Since this fly's introduction into Uruguay in 1992, pest management practices used to control the insect have been exclusively based on the use of insecticides, which has caused synthetic pyrethroid resistance. The use of insecticides is a major constraint to livestock production due to food safety and environmental concerns. This study evaluated the effectiveness of a walk-through fly trap for horn fly control. The field trail was conducted in 18 trail evaluations dates from 2015 to 2016 in Holstein-Frisian lactating cows on two dairy farms in southern Uruguay. The traps were placed at the exit of the milking parlor. Two digital cameras were used to record video at the entrances and exits of the traps. On each of the 18 trail evaluation, between 30 and 158 cows were randomly selected for fly counting according to video records. On Farm 1, a total of 718 cows were assessed. The median number of flies per cow at the entrance of the traps was 22 (ranging from 1 to 199), while the median number at the exit was three flies per cow (ranging from 0 to 22). The median efficiency of the trap was 88%. Farm 2 had 345 observations, and the median fly count at the entrance of the traps was of 22 flies per cow (ranging from 1 to 129) and four flies at the exit (ranging from 0 to 35) with a median efficiency of 82%. It was observed that the effectiveness of the fly traps varied depending on the number of flies at entry, the season of the year and the farm site. In conclusion, fly traps could be used for the control of H. irritans in milking cows without the use of insecticides.

Elimination of Taenia solium Transmission in Northern Peru.

BACKGROUND: Taeniasis and cysticercosis are major causes of seizures and epilepsy. Infection by the causative parasite Taenia solium requires transmission between humans and pigs. The disease is considered to be eradicable, but data on attempts at regional elimination are lacking. We conducted a three-phase control program in Tumbes, Peru, to determine whether regional elimination would be feasible. METHODS: We systematically tested and compared elimination strategies to show the feasibility of interrupting the transmission of T. solium infection in a region of highly endemic disease in Peru. In phase 1, we assessed the effectiveness and feasibility of six intervention strategies that involved screening of humans and pigs, antiparasitic treatment, prevention education, and pig replacement in 42 villages. In phase 2, we compared mass treatment with mass screening (each either with or without vaccination of pigs) in 17 villages. In phase 3, we implemented the final strategy of mass treatment of humans along with the mass treatment and vaccination of pigs in the entire rural region of Tumbes (107 villages comprising 81,170 people and 55,638 pigs). The effect of the intervention was measured after phases 2 and 3 with the use of detailed necropsy to detect pigs with live, nondegenerated cysts capable of causing new infection. The necropsy sampling was weighted in that we preferentially included more samples from seropositive pigs than from seronegative pigs. RESULTS: Only two of the strategies implemented in phase 1 resulted in limited control over the transmission of T. solium infection, which highlighted the need to intensify the subsequent strategies. After the strategies in phase 2 were implemented, no cyst that was capable of further transmission of T. solium infection was found among 658 sampled pigs. One year later, without further intervention, 7 of 310 sampled pigs had live, nondegenerated cysts, but no infected pig was found in 11 of 17 villages, including all the villages in which mass antiparasitic treatment plus vaccination was implemented. After the final strategy was implemented in phase 3, a total of 3 of 342 pigs had live, nondegenerated cysts, but no infected pig was found in 105 of 107 villages. CONCLUSIONS: We showed that the transmission of T. solium infection was interrupted on a regional scale in a highly endemic region in Peru. (Funded by the Bill and Melinda Gates Foundation and others.).

Geographic correlation between tapeworm carriers and heavily infected cysticercotic pigs.

BACKGROUND: Neurocysticercosis is a leading cause of preventable epilepsy in the developing world. Sustainable community-based interventions are urgently needed to control transmission of the causative parasite, Taenia solium. We examined the geospatial relationship between live pigs with visible cysticercotic cysts on their tongues and humans with adult intestinal tapeworm infection (taeniasis) in a rural village in northern Peru. The objective was to determine whether tongue-positive pigs could indicate high-risk geographic foci for taeniasis to guide targeted screening efforts. This approach could offer significant benefit compared to mass intervention. METHODS: We recorded geographic coordinates of all village houses, collected stool samples from all consenting villagers, and collected blood and examined tongues of all village pigs. Stool samples were processed by enzyme-linked immunosorbent assay (ELISA) for presence of Taenia sp. coproantigens indicative of active taeniasis; serum was processed by enzyme-linked immunoelectrotransfer blot for antibodies against T. solium cysticercosis (EITB LLGP) and T. solium taeniasis (EITB rES33). FINDINGS: Of 548 pigs, 256 (46.7%) were positive for antibodies against cysticercosis on EITB LLGP. Of 402 fecal samples, 6 (1.5%) were positive for the presence of Taenia sp. coproantigens. The proportion of coproantigen-positive individuals differed significantly between residents living within 100-meters of a tongue-positive pig (4/79, 5.1%) and residents living >100 meters from a tongue-positive pig (2/323, 0.6%) (p = 0.02). The prevalence of taeniasis was >8 times higher among residents living within 100 meters of a tongue-positive pig compared to residents living outside this range (adjusted PR 8.1, 95% CI 1.4-47.0). CONCLUSIONS: Tongue-positive pigs in endemic communities can indicate geospatial foci in which the risk for taeniasis is increased. Targeted screening or presumptive treatment for taeniasis within these high-risk foci may be an effective and practical control intervention for rural endemic areas.

Liver transplantation with monosegment from a living donor.

The shortage of organ donors for low-weight liver transplant recipients, especially for small children, has led to the development of new surgical techniques to increase the donor pool. Almost all of these techniques use the left lateral segment (Couinaud's segments II and III), but even this graft could be too large for children under 10 kg. We report here the case of an 8-month-old boy, weighing 6.1 kg, who received a monosegmental graft (segment III) from his grandmother weighing 68 kg. The graft was reduced at the donor surgery, before clamping of the vessels. The donor was discharged on the fourth post-operative day; the recipient had an uneventful post-operative period and was discharged after 22 days.