title: [Spatio-temporal pattern of larvae and eggs of gastrointestinal nematodes in cattle pastures in Veracruz, Mexico].
abstract: The spatial and temporal distribution of gastrointestinal nematodes of cattle has been little studied in Mexico. Previous studies have described periods of higher larval presence, vertical and horizontal migration in grasslands, and the frequency of adult nematodes; as well as the effect of pasture trichomes on the migration and survival of Haemonchus larvae. The aim of this study was to determine the time-space layout and spread of gastrointestinal nematode larvae on pasture, and to estimate the effect of ivermectin applied to cattle on the time-dependent abundance of their eggs in a ranch in Veracruz. To determine the spatio-temporal arrangement, monthly morning grass samples were obtained from 30 sampling points from July 2008 to June 2009. Third stage larvae (L3) from each point were counted, and aggregation patterns were estimated through variance/mean and negative binomial K indices. Additionally, the number of eggs per gram in cattle feces was determined, from samples with (CI) and without ivermectin (SI), using standard techniques. A total of 20 276 L(3) larvae were recovered in the pasture, of which an 80% corresponded to Haemonchus contortus. The highest nematode density with more than 5 000L(3)/kgDM was detected in October 2008, and the lowest in February and March 2009. The L3 showed an aggregated spatial pattern of varying intensity throughout the year. The number of eggs in the stool was not reduced with the ivermectin application to cattle, which suggested a failure of control. However, the highest parasite loads were observed from July to November 2008. We concluded that the application of ivermectin was not effective to control nematodes eggs, and that L3 populations fluctuated on pasture for ten months, providing an infection source to grazing animals afterwards.
authors.affiliation: Instituto Tecnol6gico de Tizimin, Final Aeropuerto Cupul S/N, C.P. 97700, Tizimin, Yucatán. cflota@colpos.mx
authors.forename: Carolina
authors.initials: C
authors.lastname: Flota-Bañuelos
authors.affiliation: Instituto de Ecologia, A.C. Red de Ecoetología, Carretera a Coatepec 351, El Haya, Xalapa, C.P. 91070, Veracruz, México.
authors.forename: Imelda
authors.initials: I
authors.lastname: Martínez
authors.affiliation: Colegio de Postgraduados, Campus Veracruz, Carretera Federal Veracruz-Xalapa Km 88.5 predio Tepetates. C.P. 91690, Veracruz, México.
authors.forename: José
authors.initials: J
authors.lastname: López-Collado
authors.affiliation: Colegio de Postgraduados, Campus Veracruz, Carretera Federal Veracruz-Xalapa Km 88.5 predio Tepetates. C.P. 91690, Veracruz, México.
authors.forename: Mónica
authors.initials: M
authors.lastname: Vargas Mendoza
authors.affiliation: Colegio de Postgraduados, Instituto de Fitosanidad, km 35.5 Carr. México-Texcoco, Montecillo, Edo de México.
authors.forename: Hector
authors.initials: H
authors.lastname: González Hernández
authors.affiliation: Colegio de Postgraduados, Campus Veracruz, Carretera Federal Veracruz-Xalapa Km 88.5 predio Tepetates. C.P. 91690, Veracruz, México.
authors.forename: Pernilla
authors.initials: P
authors.lastname: Fajersson
mesh_terms: D000818:Animals; D000977:Antiparasitic Agents / Q000008:administration & dosage; D002417:Cattle; D002418:Cattle Diseases / Q000188:drug therapy / Q000469:parasitology*; D005243:Feces / Q000469:parasitology; D006188:Haemonchiasis / Q000188:drug therapy / Q000469:parasitology / Q000662:veterinary*; D006189:Haemonchus / Q000302:isolation & purification*; D007411:Intestinal Diseases, Parasitic / Q000469:parasitology / Q000662:veterinary*; D007559:Ivermectin / Q000008:administration & dosage; D007814:Larva; D008800:Mexico; D010270:Parasite Egg Count / Q000662:veterinary; D006109:Poaceae / Q000469:parasitology; D013029:Space-Time Clustering
chemical_list: D000977:Antiparasitic Agents; D007559:Ivermectin