The purpose of this work was to determine the extent and effects of infestation of the eye worm of mammals, Thelazia californiensis, and to elucidate through experimentation or observation the mode of transmission.

A survey of literature revealed that thelaziasie (infestation by Thelazia species) may cause serious pathological changes in the eye and its adnexa, sometimes resulting in blindness. It was found that reports of thelaziasis in the United States were (with two exceptions) of cases in California. It was further found that T. californiensis has been reported in a wider variety of host than has any of other thelazias. The hosts were found to include many wild animals, most of the domestic animals, and men. From Russian literature it was learned that muscid flies were intermediate hosts of the thelazias found in that country.

A detailed description of the viviparous worm (male and female) and the larva is given.

One phase of the work is concerned with observing the conduct of muscid files in the vicinity of infested dogs in areas endemic for the eye worm. The flies, Fannis canicularis and F. benhamini, were observed to manifest a marked avidity for the eyes of dogs and other mammals. Information was gained through laboratory experiments and field observations strongly suggest that the latter is the intermediate host of the parasite.

A second phase of work is concerned with reservoir host studies. Animals found involved were dogs, domestic silver fox, deer, coyotes, and jack rabbits. Information gained during this phase of work suggests that the jack rabbit may be the optimal host, and that during years when these animals are plentiful, they may constitute a large portion of the reservoir. During this part of the study it was learned that the endemic areas are in mountainous or hilly regions which are amply shaded and supplied with moisture.

On the basis of these studies it was concluded that thelaziasis is an serious infestation, endangering the sight of the host, that it has infested a wider variety of animals than has any other members of the genus, and that transmission is probably thought the fly, F. benjamini.

LLU Discipline





Graduate Studies

First Advisor

Edward D. Wagner

Second Advisor

Jack D. Zwemer

Third Advisor

Richard M. Ritland

Fourth Advisor

J. Earl Thomas

Fifth Advisor

Robert W. Woods

Degree Name

Master of Science (MS)

Degree Level


Year Degree Awarded


Date (Title Page)




Library of Congress/MESH Subject Headings

Parasites; Spiruroidea



Page Count

v; 65

Digital Format


Digital Publisher

Loma Linda University Libraries

Usage Rights

This title appears here courtesy of the author, who has granted Loma Linda University a limited, non-exclusive right to make this publication available to the public. The author retains all other copyrights.


Loma Linda University Electronic Theses and Dissertations

Collection Website



Loma Linda University. Del E. Webb Memorial Library. University Archives