Laboratory transmission of lymphatic filariasis by vector mosquitoes.

Aedes togoi and Ae. aegypti were used to examine the transmission potential of Brugia pahangi to one of its natural hosts, the domestic cat. Although a larger proportion of microfilariae taken in by Ae. togoi developed into infective larvae, the total number of B. pahangi larvae recovered from a cat exposed to Ae. aegypti was larger than from a cat exposed to Ae. togoi. Factors influencing the transmission dynamics included: development of microfilariae to infective larvae; survival of mosquitoes; willingness to take repeated blood meals; and proportion of infective larvae that egress from mosquitoes during the feeding process. From 19 to 25% of infective larvae were transferred to a susceptible host. The feasibility of using a Brugia-cat model to do comparative vector efficiency studies was demonstrated.

Use of 99mTc-sulfur colloid to assess lymphatic dysfunction in filarial infection.

Investigations of lymphatic dysfunction in animals infected with filarial parasites has been hampered by a paucity of techniques to measure efficiency of lymphatic drainage. In this study a 99mTc-sulfur colloid technique was used to assess the efficiency of lymphatic drainage in Patas monkeys infected with filarial nematodes. In all 15 uninfected hind limbs there was rapid and consistent appearance of labeled colloid in the primary lymph node (popliteal) and subsequently in the secondary nodes (abdomino-pelvic) in 11 of 15 limbs. In contrast, in all eight limbs tested 1-9 months after infection there was reduced rate of migration of the colloid and initial appearance in the abdomino-pelvic region: subsequent accumulation was seen in the popliteal region in only four of the limbs. This data indicated that lymphatic vessels were blocked and that collateral vessels channeled the colloid to the secondary lymph nodes. The lymph flow patterns demonstrated by the isotope technique were supported at autopsy.

Serum levels of a filaricide, diethylcarbamazine citrate, in cats following different routes of administration.

We have reported the blood levels of diethycarbamazine (DEC) and the persistence of the drug in the circulation for several routes and protocols of DEC administration in cats. This information will be helpful in studies using the Brugia-cat model for studies of experimental chemotherapy.

Efficacy of oral and transepidermal application of diethylcarbamazine citrate in Brugia malayi infected cats.

This experimental study showed that daily oral administration of DEC at levels of 5 to 15 mg/kg/day with food for 3 weeks decreased the level of both developing and adult B. malayi in infected cats. There were no adverse reactions due to the medication. Topical application of 5% DEC in skin cream or in mineral oil appears to be effective in killing developing B. malayi in cats.

Chronic infection of cats with Brugia malayi and streptococcus.

An elephantoid condition was seen in the affected limbs of 5 of 6 cats at necropsy 12 to 18 months after initial infection with Brugia malayi. Repeated infection with Brugia and exposure to an opportunistic streptococcus appeared to enhance the production and persistence of edematous and fibrotic tissues surrounding the affected lymphatics.

Antistreptolysin O titers of cats infected with Brugia malayi and with streptococci.

This study evaluated the usefulness of determining antistreptolysin O(ASO) titers in filariasis. The ASO titers were elevated in most convalescence sera, but did not reflect comparable pathology resulting from dual Brugia-streptococcal infections in cats.