8 research outputs found
ソロモン島における昆虫成長制御剤ピリプロキシフェンの Anopheles farauti に対する野外効力評価
金沢大学留学生センター昆虫に対して高い幼若ホルモン様活性を示すピリプロキシフェン(S-31183)のAnopheles farautiに対する野外効力試験を, ソロモン諸島国, ガダルカナル島北部の淡水および半塩水の発生源で行った。その結果, ピリプロキシフェン乳剤の0.1ppm施用により, 淡水, 半塩水のいずれの発生源においても約2カ月以上にわたって70%以上の防除効果が得られた。ピリプロキシフェンの散布後に採集された幼虫および蛹が白色化しているのが観察され, 羽化阻害効果が持続する期間, この現象が続いた。 A field study to control the malarian vector, Anopheles farauti, with an insect growth regulator, pyriproxyfen (S-31183), was carried out in northern Guadalcanal in the Solomon Islands. An emulsifiable concentrate of 1% pyriproxyfen was applied to two breeding sites : one with fresh water and another with brackish water. Pyriproxyfen at a dosage of 0.1ppm inhibited emergence of An. farauti completely, at both test sites, for at least 5 weeks after treatment and the efficacy (more than 70% inhibition) lasted for ca. 2 months. The body color of the larvae and pupae in the test sites whitened noticeably after the application of the compound
Resistance of Anopheles farauti eggs to desiccation
金沢大学留学生センターソロモン諸島国におけるマラリアの主媒介種であるAnopheles farautiの卵の耐乾性を調べるために, 実験コロニーより得られた卵を使って室内実験を行った。濡れたペーパータオルまたは濡れた枯葉の上に, 夜間産まれた卵を翌朝そのまま室内で乾燥させ, 温度29±2℃, 湿度70∿90%の条件下で保存した。次の日から一部を水に浸し, 孵化する卵の割合を10日間にわたって調べた。孵化率は乾燥期間が長くなるにしたがい低下したが, 少数の卵は6日間の乾燥の後でも生き残り, 孵化した
Permethrin impregnated bednets and DDT residual spraying, multicentre comparative trial in Solomon Islands
A malaria intervention comparative trial
was
carried out
in
Solomon Islands
between 1987 and 1992, involving 7
pairs
14
communities, with
29,182
people.
Seven
communities were given bed nets
impregnated
with
permethrin annually
at
0.5g/m2,
and the others sprayed biannually with
DDT
at
dosage
2g/m2.
Each
pair was
evaluated for about two years,
by
measuring entomological
indices,
prevalence
of
infection, incidence of infection, and
levels
of community
compliance.
An intensive
differential cost analysis of
both interventions
was
done in
one pair
of the
communities and an analysis on
cost and
benefit
of
PCD
mechanism
was
done in
three pairs.
Anopheles farauti, the main vector,
(A.
punctulatus,
an
inland
vector
became
very rare with interventions), maintained the
early
evening
biting
peak
and
high
outdoor biting. The highest transmission
potential
was
indoor
with
high
parity
(54.1%) and sporozoite rate (1.42%). It
avoided
contact
on
DDT
sprayed
surface and
was not killed even though it
was
still
sensitive with a
75.1%
mortality.
There
were neither changes in biting density,
nor
parous
rates
with
DDT
spraying.
Permethrin impregnated bed nets reduced
biting
density
by
an
estimated
53.69%. The
parous rate indoor was reduced
by
11.64%
when
compared
with that
in the
comparison area, and those caught
in the
bed
nets
area
did
not
have
any
sporozoites. Prevalence of
infection, by
quarterly
prevalence surveys revealed
a
21.2% difference between the
intervention
areas
after two
years.
The
most
significant decline was in the
under
10
year
old
group
(p<0.01) in
permethrin
treated bed nets, including in infants
(p<0.05).
The
decline
was
especially
marked
with Plasmodium falciparum. There
were
increases in the
DDT
area,
including P. falciparum in the younger age
groups.
DDT
spraying
did
not
have
any effect
on
the incidence of infection. Permethrin impregnated
bed
nets reduced
malaria
incidence, by an estimated
49%.
This
reduction
was particularly
significant
however
on children under ten years old
(p<0.0001)
and
marked with
P. falciparum.
Compliance with DDT declined
by 30%
but
with
bednets it
remained
high
above 85%. These results confirmed that
permethrin
impregnated bednets
are
more
effective than DDT residual spraying
in
controlling
malaria
in Solomon Islands.
The operational costs for DDT spraying was
3.85
per capita per year. The mean cost of processing
and
examining
a
PCD
slide
is
$0.40.
These cost indices took account of all
materials,
personnel
and
administration
involved. It took a mean of
6.1
days from the time the
smear
was taken to the time
examined (SE = 0.21,95%CI 5.71 to
6.53
days). It
would take twice this time
for
a
result to be received by the
health
workers
managing
patients.
Only
20%
of
blood
slides could contribute to patient
management.
Based
on these
findings,
all that
is necessary is to make blood smears
of
patients
less than
10
years
of age
for
epidemiological evaluation of vector
control
interventions in
malaria
programme.
This will save scarce resources at
primary
health
care
level.
Making
blood
slides
of everyone would not further add significant
information
and
benefit,
at an
extra
cost. The only exceptions are, those
critically
ill
with malaria,
complicated
malaria and a patient suspected to
have
drug
resistant
malaria.
Permethrin
impregnated bednets are a cost effective way to
control malaria
in
primary
health
care and the most cost benefit way to
evaluate vector control
intervention is
careful monitoring of PCD results, especially
with
P. falciparum
malaria of
children under 10 years old