A CHRONOLOGICAL LYMPHOGRAPHIC STUDY OF CATS EXPERIMENTALLY INFECTED WITH BRUGIA FILARIASIS FROM 5 DAYS TO 5 YEARS

Abstract

1. Chronological investigations on the pathogenesis of filariasis were conducted in an experimental model using lymphography with supporting histopathology.

2. The model chosen was B. pahangi and B. patei infections in cats. In order to delineate the changes in the filarial infected lymphatic vessels and nodes, the technique of direct visual lymphography perfected by Kinmonth in 1955 was employed in both uninfected and filarial infected cats.

3. Eight cats varying in age from a few weeks to 2 years and weighing 1 kg to 5 kgs were used in investigating normal lymphographic patterns in the hind limbs.

4. Thirteen cats with pre-patent infections of B. pahangi, nine cats with patent B. pahangi infections and three with patent B. patei were investigated. In addition five long-standing B. patei infections ranging from 3 years 10 months to 5 years 9 months were also investigated.

5. Lymphographic changes were visible in the lymphatic vessels and nodes of the infected limbs as early as the 15th day after inoculation. In 19 of the cats changes were confined to the limb receiving the inoculation of larvae while in 4 of these cats changes were additionally visible in the nodes and afferent lymphatic vessels of the opposite side. In the five cats inoculated with larvae into both hind limbs or into all 4 limbs, lymphatic changes were always visible in the limbs receiving the larvae.
 
The main changes seen on lymphography and supported by histopathology were as follows:
A. Dilatation of the lymphatics.
B. Enlargement of the nodes.
C Tortuosity of the lymphatics with simultaneous dilatation.
D. Leakage of contrast medium.
E. Stasis of contrast medium.
F. Collateral formation and lymphatic anastomoses.

6. The lymphographic observations in Brugia infected cats provide several criteria distinguishing filarial from non-filarial lymphatic diseases, the stage of the infection in experimentally infected cats, and the degree of lymphatic involvement.