Infection pattern of the spirurid nematode Protospirura numidica criceticola in the cricetid rodent Akodon azarae on poultry farms of central Argentina.

Abstract

The nematode Protospirura numidica criceticola infects the stomach of Neotropical cricetid rodents when they ingest infected arthropods. In North America, prevalence values fluctuated, showing marked peaks in desert habitats, while remaining low in humid environments. The infection pattern has not been studied in South American rodents. In this work, yearly infection by P. n. criceticola was analysed in the South American cricetid Akodon azarae seasonally captured from July 1998 to July 2000 and in March 2001 on poultry farms of a humid region of Argentina. Seasonal occurrence of third- and fourth-stage larvae and adults was recorded. Seasonal population and community parameters of the parasite were calculated. The occurrence of larval stages was confirmed for the four seasons. Prevalence fluctuated between 0 and 36% and did not show a seasonal pattern. It was not related to the abundance of A. azarae (rs = 0.37) or to rainfall. In this humid region of Argentina, where food resources are diverse throughout the year, the omnivorous A. azarae may have a variable diet so that infection can occur in the four seasons. Prevalence values were not very high, in accordance with observations in humid habitats of North America. The infection was also characterized by low intensity, abundance and dominance. Only 3.8% of the rodents were parasitized with three or more specimens of the parasite, and that was only in autumn. It is suggested that rodents can not overwinter successfully with a heavy biomass of stomach parasites.