Page 111 - Medical Parasitology_ A Textbook ( PDFDrive )

104 10 Nematodes: Roundworms

Fig. 10.16 Brugia
malayi microfilariae

B. malayi shows nocturnal periodic (microfilariae are not detectable in the blood
for the majority of the day, but the microfilarial density peaks between 10 pm and 2
am) and nocturnal subperiodic forms (microfilariae are present in the blood at all
times, but appear at greatest density between noon and 8 pm). The nocturnal peri-
odic form is transmitted by Mansonia and some Anopheline mosquitoes in open
swamps and rice growing areas. Natural animal infections are rare. The nocturnal
subperiodic form is transmitted by Mansonia in forest swamps. Natural zoonotic
infections are common. Animals including cats, dogs and monkeys may serve as
important reservoirs for human infection.

Prevention and Control
Prevention and control methods are similar to W. bancrofti. The breeding of
Mansonia mosquito requires water plants, without which Mansonia mosquito can-
not breed.

Brugia timori

Brugia timori is limited to Timor island of Eastern Indonesia. The vector of B.
timori is Anopheles barbirostris, which breeds in rice fields and is a night feeder.
Definitive host is human and no animal reservoir is known. Microfilariae of B.
timori exhibit nocturnal periodicity. The microfilaria sheath of B. timori fails to take
Giemsa stain. The cephalic space ratio is 3:1. The lesions produced by B. timori are
milder than those of bancroftian or B. malayi filariasis. DEC and albendazole are
used in the treatment of Brugia timori filariasis.