Hassalstrongylus musculi is a nematode worm of the genus Hassalstrongylus that infects the marsh rice rat (Oryzomys palustris) and house mouse (Mus musculus) in the United States[1] and Oryzomys couesi, Oligoryzomys fulvescens, and Handleyomys melanotis in San Luis Potosí, Mexico.

[2] It was first described as Longistriata musculi by Dikmans in 1935, but transferred to Hassalstrongylus in 1971 and 1972 by Marie-Claude Durette-Desset.

She later renamed the material she had used to describe H. musculi in 1972 as H. forresteri.

[3] The females cannot be distinguished from those of the other species in the marsh rice rat, H. forresteri and H. lichtenfelsi.

[4]