Laboratory and field studies of mansonia and coquilleitidia mosquitoes in relation to ecology and transmission of filariasis in Malaysia
Loading...
Date
1987-04
Authors
Geok Lian, Chiang
Journal Title
Journal ISSN
Volume Title
Publisher
Abstract
A supportive programme to control Mansonia and Coguillettidia
vectors awaits formulation till some aspects of ecology of these
mosquitoes and parameters associated with the dynamics of
'transmission of filariasis are better understood. It was in
response to these needs that the present study was carried out.
Included in this study were the following: to establish strong
colonies of Mansonia spp. and Coguillettidia crassipes to provide
materials for laboratory studies; to study their susceptibility to
human and animal filariae; and to conduct field studies on their
ecology in relation to transmission of filarial parasites in
different ecotypes.
Mansonia uniformis, Mansonia indiana, Mansonia bonneae and Cq.
crassipes were successfully colonized using liver-yeast and guinea
pig dung infusions as larval media and plants and wet strength paper
for larval attachment. The new liver yeast medium and paper
cultures developed in this study constituted a simplified and
convenient technique suitable for rearing the mosquitoes on a large
scale for laboratory studies.
Findings of the susceptibility study of Mansonia spp. to
periodic and subperiodic Brugia malayi and Brugia pahangi concur
with those of earlier workers. Strains of Ma. 'uniformis from
endemic and non-endemic areas were shown to be equally efficient in
supporting the development of subperiodic B. malayi <p > 0.05).
Studies on the species composition, seasonal abundance,
filarial infection, survivorship, age composition and biting cycles
of Mansonia were carried out in two ecotypes in Selangor, Peninsular
Malaysia - a swamp forest in Jalan Tanjong Karang and an open swamp
rice~ field in Lubuk Pusing. Ma. uniformis was the predominant
species in both ecotypes. The seasonal abundance was generally
similar in all species. There was an increase in the abundance
generally from July to November coinciding with rainfall. Results
of~infection indicated that Ma. uniformis and Ma. annulata in Jalan
Tanjong Karang and Ma. uniformis and Ma. indiana in.Lubuk Pusing
were the probable vectors of ~ malayi. There was no difference in
the pattern of biting of nulliparous and parous populations, with a
general peak period of activity between 1800-2000 hours in both
ec~types.
di~cussed.
Observed differences between the two study areas were
The parous rates coupled with high daily mortality
(27.9-43.8%) of the mosquitoes could have been important factors
preventing active transmission in the two ecotypes as indicated by
the low Annual Infective Biting Rate (AIBR) and Annual Transmission
Potential (ATP) estimated for the vectors concerned. The epidemiological
importance of these two entomological parameters (AIBR
and ATP) was discussed.
Mark-release-recapture experiments demonstrated that Ma.
uniformis had a mean dispersal distance ranging from 1.45 to 1.71 km
in an open swamp ecotype. The longest flight distance recorded was
3.50 km. Based on these findings, the importance of reinvasion must
be recognised when control operation is restricted to small areas.
The duration of the gonotrophic cycle for Ma. uniformis was
estimated to be 3-4 days.
Natural and laboratory infection studies indicated that ~
crassipes was capable of transmitting~ malayi. Two ~ crassipes
with L3 Brugia in Jalan Tanjong Karang appeared to be the first
record in Malaysia. The field studies also provided evidence of
similarity in seasonal abundance, biting activity and survivorship
of ~ crassipes to the Mansonia vectors in the same study area
t where their breeding habitats overlap.
In the studies on the surveillance of adult ~ crassipes, IMR
traps with bird baits proved to be a convenient and satisfactory
method of sampling the mosquitoes. Vertical distribution showed
that greater numbers of the mosquitoes were caught at higher than
~~ lower elevations.
Based on the morphology of the adult worms recovered and microfilarial
stages in naturally and experimentally infected chickens, a
bird filarioid Cardiofilaria nilesi was shown to be present in
Malaysia. The presence of infective larvae in wild caught
mosquitoes indicated th~t ~ crassipes was the principal vector of
C. nilesi in birds.
Experimental transmission of C. nilesi in chickens and jirds
was successfully carried out using laboratory bred ~ crassipes.
The results demonstrated for the first time that a filarioid parasite
from bird can be transmitted to a mammal. The short prepatent
period, prolonged patent period and the nocturnal subperiodic
pattern of periodicity observed during the study co~ld contribute to
the establishment of an ideal model in the jird for not only basic
studies on host- parasite relationship but also for screening
potential filaricides.
Description
Keywords
Coquilleitidia mosquitoes , Filariasis in Malaysia