Determinación de índice simplificado de calidad de agua en el río Chili, Arequipa 2019

Se plantea a partir de características microbiológica y fisicoquímicas establecer el índice simplificado de calidad de agua; dentro de las características microbiológicas consideradas para 05 puntos de muestreo del río Chili que se encuentran dentro del área de influencia de Arequipa metropolitana; los cuales son RIO 01- Parte alta de Chilina, RIO 02 - Puente San Martin, RIO 03 - Puente San Isidro, RIO 04 - Puente Tiabaya y RIO 05 - Zona Congata; siendo el RIO 02 y RIO 03 los que tienen una mayor influencia urbana, y el RIO 01, RIO 04 y RIO 05 se encuentran rodeados de terrenos de cultivo. En cuanto a los coliformes totales los valores más altos fueron encontrados en los puntos de muestreo RIO 02 y RIO 03, que corresponden al puente de San Martín y el puente de San Isidro respectivamente, mientras que el valor más bajo se reporta para el punto de muestreo RIO 01 que corresponde a la parte alta de Chilina; por otro lado para el caso de coliformes termotolerantes el valor más alto se reporta para el punto de muestreo RIO 03 que corresponde al puente de San Isidro; se han considerado cinco parámetros fisicoquímicos que deben ser tomados en cuenta para el cálculo del índice simplificado de calidad de agua los cuales son: temperatura, demanda bioquímica de oxigeno (DBO5), Solidos Totales en Suspensión (SST), Oxígeno Disuelto (OD) y Conductividad; al comparar los parámetros microbiológicos con los estándares de calidad ambiental (ECA), se determina que los puntos de muestreo RIO 02, RIO 03 y RIO 04 superan el estándar de calidad ambiental; por otro lado ningún parámetro físico químico supera el estándar de calidad ambiental; respecto al índice simplificado de calidad de agua se determina que todos los puntos de muestreo se encuentran en el rango de 71 a 90 de la escala arbitraria, el mismo que corresponde a una calidad buena de agua; sin embargo el índice microbiológico establecido por la presencia de coliformes termotolerantes que se encuentran por encima del estándar de calidad ambiental indican que los puntos de muestreo RIO 02, RIO 03 y RIO 04 presentan una mala calidad de agua

Dispersal patterns of Trypanosoma cruzi in Arequipa, Peru.

Anthropogenic environmental alterations such as urbanization can threaten native populations as well as create novel environments that allow human pests and pathogens to thrive. As the number and size of urban environments increase globally, it is more important than ever to understand the dispersal dynamics of hosts, vectors and pathogens of zoonotic disease systems. For example, a protozoan parasite and the causative agent of Chagas disease in humans, Trypanosoma cruzi, recently colonized and spread through the city of Arequipa, Peru. We used population genomic and phylogenomic tools to analyze whole genomes of 123 T. cruzi isolates derived from vectors and non-human mammals throughout Arequipa to determine patterns of T. cruzi dispersal. The data show significant population genetic structure within city blocks-parasites in the same block tend to be very closely related-but no population structure among blocks within districts-parasites in neighboring blocks are no more closely related to one another than to parasites in distant districts. These data suggest that T. cruzi dispersal within a block occurs regularly and that occasional long-range dispersal events allow the establishment of new T. cruzi populations in distant blocks. Movement of domestic animals may be the primary mechanism of inter-block and inter-district T. cruzi dispersal

Sexual reproduction in a natural Trypanosoma cruzi population.

BackgroundSexual reproduction provides an evolutionary advantageous mechanism that combines favorable mutations that have arisen in separate lineages into the same individual. This advantage is especially pronounced in microparasites as allelic reassortment among individuals caused by sexual reproduction promotes allelic diversity at immune evasion genes within individuals which is often essential to evade host immune systems. Despite these advantages, many eukaryotic microparasites exhibit highly-clonal population structures suggesting that genetic exchange through sexual reproduction is rare. Evidence supporting clonality is particularly convincing in the causative agent of Chagas disease, Trypanosoma cruzi, despite equally convincing evidence of the capacity to engage in sexual reproduction.Methodology/ principle findingsIn the present study, we investigated two hypotheses that can reconcile the apparent contradiction between the observed clonal population structure and the capacity to engage in sexual reproduction by analyzing the genome sequences of 123 T. cruzi isolates from a natural population in Arequipa, Peru. The distribution of polymorphic markers within and among isolates provides clear evidence of the occurrence of sexual reproduction. Large genetic segments are rearranged among chromosomes due to crossing over during meiosis leading to a decay in the genetic linkage among polymorphic markers compared to the expectations from a purely asexually-reproducing population. Nevertheless, the population structure appears clonal due to a high level of inbreeding during sexual reproduction which increases homozygosity, and thus reduces diversity, within each inbreeding lineage.Conclusions/ significanceThese results effectively reconcile the apparent contradiction by demonstrating that the clonal population structure is derived not from infrequent sex in natural populations but from high levels of inbreeding. We discuss epidemiological consequences of this reproductive strategy on genome evolution, population structure, and phenotypic diversity of this medically important parasite

Immigration and establishment of Trypanosoma cruzi in Arequipa, Peru.

Changing environmental conditions, including those caused by human activities, reshape biological communities through both loss of native species and establishment of non-native species in the altered habitats. Dynamic interactions with the abiotic environment impact both immigration and initial establishment of non-native species into these altered habitats. The repeated emergence of disease systems in urban areas worldwide highlights the importance of understanding how dynamic migratory processes affect the current and future distribution and abundance of pathogens in urban environments. In this study, we examine the pattern of invasion of Trypanosoma cruzi-the causative agent of human Chagas disease-in the city of Arequipa, Peru. Phylogenetic analyses of 136 T. cruzi isolates from Arequipa and other South American locations suggest that only one T. cruzi lineage established a population in Arequipa as all T. cruzi isolated from vectors in Arequipa form a recent monophyletic group within the broader South American phylogeny. We discuss several hypotheses that may explain the limited number of established T. cruzi lineages despite multiple introductions of the parasite