Which trap is best? Alternatives to outdoor human landing catches for malaria vector surveillance: a meta-analysis.

BACKGROUND: Human landing catches (HLC) are an entomological collection technique in which humans are used as attractants to capture medically relevant host-seeking mosquitoes. The use of this method has been a topic of extensive debate for decades mainly due to ethical concerns. Many alternatives to HLC have been proposed; however, no quantitative review and meta-analysis comparing HLC to outdoor alternative trapping methods has been conducted. METHODS: A total of 58 comparisons across 12 countries were identified. We conducted a meta-analysis comparing the standardized mean difference of Anopheles captured by HLC and alternative traps. To explain heterogeneity, three moderators were chosen for analysis: trap type, location of study, and species captured. A meta-regression was fit to understand how the linear combination of moderators helped in explaining heterogeneity. The possibility of biased results due to publication bias was also explored. RESULTS: Random-effects meta-analysis showed no statistically significant difference in the mean difference of Anopheles collected. Moderator analysis was conducted to determine the effects of trap type, geographical location of study, and the species of Anopheles captured. On average, tent-based traps captured significantly more Anopheles than outdoor HLC (95% CI: [- .9065, - 0.0544]), alternative traps in Africa captured on average more mosquitoes than outdoor HLC (95% CI: [- 2.8750, - 0.0294]), and alternative traps overall captured significantly more Anopheles gambiae s.l. than outdoor HLC (95% CI: [- 4.4613, - 0.2473]) on average. Meta-regression showed that up to 55.77% of the total heterogeneity found can be explained by a linear combination of the three moderators and the interaction between trap type and species. Subset analysis on An. gambiae s.l. showed that light traps specifically captured on average more of this species than HLC (95% CI: [- 18.3751, - 1.0629]). Publication bias likely exists. With 59.65% of studies reporting p-values less than 0.025, we believe there is an over representation in the literature of results indicating that alternative traps are superior to outdoor HLC. CONCLUSIONS: Currently, there is no consensus on a single "magic bullet" alternative to outdoor HLC. The diversity of many alternative trap comparisons restricts potential metrics for comparisons to outdoor HLC. Further standardization and specific question-driven trap evaluations that consider target vector species and the vector control landscape are needed to allow for robust meta-analyses with less heterogeneity and to develop data-driven decision-making tools for malaria vector surveillance and control.

Meta-Analysis of the Use of Eimeria Lesion Scores and Oocyst Counts in Floor-Pen Studies.

The success of treatments for, or prophylaxis of, coccidiosis with classical anticoccidial feed additives or alternative treatments can be measured with a variety of metrics. Three important metrics are body weight or body weight gain (BW or BWG), lesion scores (LS), and oocyst shedding (OS). A meta-analysis of floor-pen experiments was performed to determine if using LS and OS would lead to systematically different assessments compared to the use of BW at the end of the experiment, and to what degree changes in LS and OS are correlated with BW. We also investigated if there were days postinfection on which one could expect larger ratios between untreated control groups and treated groups for LS and OS as an aid to selecting sampling days. A total of 38 experiments from 37 articles in peer-reviewed journals were included. Data sets containing experiments that investigated LS or OS in addition to BW or BWG to assess anticoccidial feed additives or alternative treatment were tested for the effectiveness of the intervention either by univariate meta-analyses for each metric or by robust variance estimation multivariate meta-analysis combining BW with LS or BW with OS. The results did not show evidence that the inclusion of LS and OS in experimental designs to assess the effect of conventional and alternative feed additives with assumed anticoccidial activity systematically changed the conclusions drawn from an experiment, but there was no significant correlation between the LS and OS ratios of untreated and treated groups determined during the experiments with the ratios of the BW at the end of the experiment for each experiment. There was also no discernible relationship between LS or OS ratios and days postinfection.

Metanálisis del uso de puntajes de lesiones de Eimeria y recuentos de ooquistes en estudios con corrales en piso. El éxito de los tratamientos o la profilaxis de la coccidiosis con aditivos alimentarios anticoccidiales clásicos o tratamientos alternativos se puede medir con una variedad de mediciones. Tres mediciones importantes son el peso corporal o la ganancia de peso corporal (BW o BWG), las puntuaciones de lesiones (LS) y la eliminación de ooquistes (OS). Se realizó un metanálisis de experimentos con corrales en piso para determinar si el uso de las puntuaciones de lesiones y eliminación de ooquistes daría lugar a evaluaciones sistemáticamente diferentes en comparación con el uso del peso corporal al final del experimento, y en qué medida los cambios en puntuaciones de lesiones y eliminación de ooquistes se correlacionan con el peso corporal. También se investigó si había días posteriores a la infección en los que se podrían esperar mayores proporciones entre los grupos de control no tratados y los grupos tratados para las puntuaciones de lesiones y la eliminación de ooquistes como ayuda para seleccionar los días de muestreo. Se incluyeron un total de 38 experimentos de 37 artículos en revistas con comité editorial. Los conjuntos de datos que contenían experimentos que investigaron las puntuaciones de lesiones o la eliminación de ooquistes además del peso corporal o la ganancia de peso corporal para evaluar los aditivos alimentarios anticoccidiales o el tratamiento alternativo se probaron para determinar la efectividad de la intervención mediante metanálisis univariados para cada medición o mediante metanálisis multivariados de estimación de varianza robusta que combinaban el peso corporal con las puntuaciones de lesiones o el peso corporal con la eliminación de ooquistes. Los resultados no mostraron evidencia de que la inclusión de las puntuaciones de lesiones y eliminación de ooquistes en diseños experimentales para evaluar el efecto de los aditivos alimentarios convencionales y alternativos con supuesta actividad anticoccidial cambiara sistemáticamente las conclusiones extraídas de un experimento, pero no hubo una correlación significativa entre las proporciones de puntuaciones de lesiones y la eliminación de ooquistes de grupos no tratados y tratados determinadas durante los experimentos con las proporciones del peso corporal al final del experimento para cada experimento. Tampoco hubo una relación perceptible entre las proporciones de puntuaciones de lesiones o la eliminación de ooquistes y los días posteriores a la infección.

Network meta-analysis comparing the effectiveness of anticoccidial drugs and anticoccidial vaccination in broiler chickens.

With the trend to organic production and concerns about using antibiotic feed additives, the control of infections with Eimeria spp. in broiler flocks has become more difficult. Vaccination against coccidia is an alternative, but there are concerns that the live vaccines used might have negative effects on production parameters and intestinal health. Reports of experiments directly comparing anticoccidial drugs and anticoccidial vaccines are rare. This network meta-analysis (NMA) identified and analyzed 61 articles reporting 63 experiments testing anticoccidial drugs and anticoccidial vaccines under conditions resembling commercial broiler production. The effect sizes were mean differences in body weight/body weight gain (BW/BWG) and feed conversion rate (FCR) between the 175 included groups. The results show that groups vaccinated against coccidia have a similar BW/BWG and FCR at processing age compared to groups given anticoccidial drugs. However, the results tended to be more favorable for anticoccidial drugs than for vaccines. The analysis of eight subsets, containing only groups (1) groups that had not received an AGP in addition to an anticoccidial drug, (2) groups that had not received ionophores, (3) groups that had not received chemicals, (4) groups that had not received an attenuated vaccine, (5) groups that had not received a fully virulent vaccine, (6) groups that were not additionally challenged with bacteria or not challenged, (7) groups that had received a severe challenge as defined by a total infection dose of more than 100,000 oocysts or were not challenged, (8) groups that were challenged on day 15 or earlier or not challenged brought similar results and confirmed the robustness of the NMA. In addition, the analysis exposes unnecessary, as well as inherent, problems with data quality, which every researcher working with coccidia should carefully consider, and identifies under-researched areas that should be addressed in future research.