Bovine thelaziasis in Massachusetts.

A survey for Thelazia sp. in Massachusetts bovines was conducted in 1977-1978. Two species of eyeworms, Thelazia gulosa and T. skrjabini, were recovered from cattle eyes obtained from abattoirs. Of 795 eyes examined 97 (12.2%) were infected with Thelazia sp. Seventy-four eyes were parasitized by T. gulosa and 8 by T. skrjabini alone, with 15 showing mixed infections. Infections were almost entirely subclinical on postmortem examination, however, in one eye a nodule of T. gulosa worms just under the surface of the conjunctiva was associated with extensive lesions and general conjunctivitis. In another instance, a mass of juvenile T. gulosa parasites in the conjunctival sac appeared to have resulted in slight scarification, localized edema and redness.