Ivermectin
versus benzyl benzoate applied once or twice to treat human
scabies in Dakar, Senegal: a randomized controlled trial
Fatimata Ly,a Eric Caumes,b Cheick Ahmet Tidiane Ndaw,c Bassirou
Ndiayed & Antoine Mahéa
Objective To compare the effectiveness of oral ivermectin (IV) and two
different modalities of topical benzyl benzoate (BB) for treating
scabies in a community setting.
Methods The trial included patients aged 5–65 years with
scabies who attended the dermatology department at the Institut
d’Hygiène Sociale in Dakar, Senegal. The
randomized, open trial considered three treatments: a single
application of 12.5% BB over 24 hours (BB1 group), two applications of
BB, each over 24 hours (BB2 group), and oral IV, 150–200
μg/kg (IV group). The primary endpoint was the disappearance of
skin lesions and itching at day 14. If necessary, treatment was
repeated and patients were evaluated until cured. Results were analysed
on an intention-to-treat basis. A pre-planned intermediate analysis was
carried out after the BB1, BB2 and IV groups had recruited 68, 48 and
65 patients, respectively.
Findings At day 14, 33 patients (68.8%) in the BB2 group were cured
versus 37 (54.4%) in the BB1 group and 16 (24.6%) in the IV group (P
< 10–6). Bacterial superinfection occurred more often
in the IV group than in the BB1 and BB2 groups combined (28% versus
7.8%, respectively; P = 0.006). At day 28, 46 patients (95.8%) in the
BB2 group were cured versus 52 (76.5%) in the BB1 group and 28 (43.1%)
in the IV group (P < 10–5). These clear findings
prompted early study cessation.
Conclusion Topical BB was clearly more effective than oral IV for
treating scabies in a Senegalese community.
Une traduction en français de ce
résumé figure à la fin de
l’article. Al final del artículo se facilita una
traducción al español.
.ةلاقلما هذهل لماكلا صنلا ةياهن في ةصلاخلا هذهل ةيبرعلا ةمجترلا
a Service de Dermatologie/Infections Sexuellement Transmissibles,
Institut d’Hygiène Sociale, Dakar, Senegal.
b Maladies Infectieuses et Tropicales, Hôpital
Pitié-Salpêtrière, Paris, France.
c Unité de Recherche sur le Paludisme, Institut de Recherche
pour le Développement, Dakar, Senegal.
d Service de Dermatologie, Hôpital Aristide le Dantec, Dakar,
Senegal.
Correspondence to Fatimata Ly (e-mail: lyfaty@yahoo.fr).
(Submitted: 26 February 2008 – Revised version received: 11
July 2008 – Accepted: 21 August 2008 – Published
online: 18 March 2009)
Introduction
Scabies is a globally occurring ectoparasitic infection whose burden
has been estimated to be as high as 300 million cases per year.1 In
developing countries, scabies is a significant public health problem
because it is highly prevalent and complications are frequent. It is
one of the main reasons for consultations in non-specialized primary
health-care centres.2 Children appear to be more commonly affected and
are at a significant risk of streptococcal superinfection, which may be
complicated by acute glomerulonephrititis.3 In addition, a recent study
performed in the Gambia showed that skin lesions associated with
scabies were the leading portal of entry for organisms that cause
septicaemia in infants aged 3 months or less.4
Several topical treatments are effective: permethrin, lindane and
benzyl benzoate (BB), with the last being considered the treatment of
choice in most parts of Africa. On the other hand, oral ivermectin (IV)
has also been shown to be effective, but the optimal number of courses
is still a matter of some controversy.
A recent meta-analysis5 reported
that, to date, there is no conclusive evidence that oral IV is superior
to topical preparations for treating common scabies in the community
setting.
We conducted a randomized controlled trial in Dakar, Senegal, to
compare three modalities of treatment for scabies (i.e. oral IV and two
forms of application of BB) with the aim of determining the most
suitable treatment regimen in our setting.
Methods
Patients were included if they presented to the Institut
d’Hygiène Sociale in Dakar, Senegal, and satisfied
the following criteria: they were aged between 5 and 65 years; they
were experiencing itching that involved at least three distinct sites
on the body and had lesions that were characteristic of scabies (i.e.
vesicles, papules, nodules or pustules) on at least three sites of
predilection for scabies (i.e. the interdigital folds of the hands, the
elbows, the wrists, the buttocks, the axillary folds, the nipple
areolas in women and the male external genitalia), as assessed by a
trained health-care worker;6 and they were willing to participate in
the study.
Patients were excluded if they satisfied any of the following exclusion
criteria: there was doubt about the diagnosis of scabies; pruritus due
to insect bites was present; the case patient or a member of his or her
family had chickenpox; or the patient had been treated for scabies less
than 1 month before the consultation; was under 5 years or over 65
years of age; weighed less than 15 kg; was pregnant or breastfeeding;
was a women who used bleaching products for cosmetic purposes; had
crusted scabies; had a general condition such as diabetes, high blood
pressure or cardiovascular or neurological disease; or lived outside of
the Dakar district.
An HIV test was not required either before or after
inclusion.
A parasitological examination was performed by low-power microscopy for
each patient included in the trial. Skin scrapings were taken from each
interdigital space in the hands and from the most clinically affected
locations elsewhere.
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Fatimata Ly et al. Treatment of human scabies in Senegal
The scrapings were placed in a drop
of 10% potassium hydroxide solution
on a glass slide and examined for the
presence of Sarcoptes scabiei (i.e. adult
forms), eggs or faecal pellets. Negative
findings on parasitological examination
did not imply exclusion from the trial.
Setting
Senegal is a sub-Saharan country with
11 million inhabitants, and its capital,
Dakar, has approximately 2 million
inhabitants. The per capita gross national
income is US$ 700. Forty per
cent of the population lives in cities.
The literacy rate is 50.4% in women
and 72.8% in men. Fifty-seven per cent
of the population is under 20 years of
age.7 The prevalence of HIV infection
in the general adult population is estimated
to be 0.8%.8 Our unit is one of
only two services that provide specialist
dermatology care in Dakar.
Interventions
A randomized, controlled, non-blinded
trial was carried out to compare three
scabies treatments: a single oral dose
of 150–200 μg/kg of IV taken on an
empty stomach (IV group); one application
of 12.5% BB, which was not
removed for 24 hours, administered
over the whole body except the head
(BB1 group); and two such applications
of 12.5% BB separated by 24 hours
(BB2 group). To reproduce conditions
found in the real world (i.e. a pragmatic
trial), the investigators did not supervise
compliance with any regimen. IV
was manufactured by Merck, Sharp
and Dohme-Chibret and was provided
by the Senegalese national programme
for controlling onchocerciasis. The expiry
dates of the different drugs were
checked.
Randomization
A random number table was used to
allocate treatment, with equilibration
of asymmetries between the three treatment
arms being carried out for every
40 patients. There was no provision for
double-blinding. The study sample size
was calculated based on the assumption
that the difference in effectiveness
between the treatment arms was less
than 15%.
The chosen significance
level was 5%, and the power of the
study was 80%. The total number of
patients scheduled for inclusion was
400, distributed as follows: 150 in the
IV group, 150 in the BB1 group and
100 in the BB2 group. Any member of
a patient’s family who was included in
the trial received the same treatment as
the index case.
At day 7, any patient who had
clearly worsened was again given the
same treatment as the week before. If at
day 7 no change was noted or the patient
had improved, nothing was done
until day 14. If treatment failure was
observed at day 14, the treatment first
given was applied again. If treatment
failure was noted at day 28, patients in
either the IV or BB1 group were scheduled
to be switched to two applications
of BB, and those in the BB2 group were
switched to IV.
Systematic cleaning of clothes and
bedding was recommended. If a patient
had a patent skin superinfection,
an oral antibiotic (i.e. amoxicillin or
erythromycin for 1 week) was given
before randomization. Family members
not included in the trial were given one
Fig. 1. Flowchart of a randomized trial comparing one or two
applications of BB
versus IV in the treatment of scabies, Dakar, Senegal
Not eligible
(n = 1242)
Eligible
(n = 759)
Patients screened
(n = 455)
Patients randomized
(n = 181)
Group BB1a
(n = 68)
Group BB2b
(n = 48)
Group IVc
(n = 65)
Lost to follow-up
(n = 8)
Lost to follow-up
(n = 0)
Lost to follow-up
(n = 11)
At day 14
60 patients remaining
Cured (n = 37)
Poor compliance (n = 17)
At day 14
48 patients remaining
Cured (n = 33)
Poor compliance (n = 12)
At day 14
54 patients remaining
Cured (n = 16)
Poor compliance (n = 3)
Lost to follow-up
(n = 2)
Lost to follow-up
(n = 0)
Lost to follow-up
(n = 1)
At day 28
21 patients remaining
Cured (n = 15)
At day 28
15 patients remaining
Cured (n = 13)
At day 28
37 patients remaining
Cured (n = 12)
At day 35
6 patients remaining
At day 35
2 patients remaining
At day 35
25 patients remaining
Patients consulting
the trial institution
(n = 2001)
BB, benzyl benzoate; IV, ivermectin.
a Group that received one application of benzyl benzoate.
b
Group that received two applications of benzyl benzoate.
c Group that received ivermectin.
426 Bull World Health Organ 2009;87:424–430 |
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Treatment of human scabies in Senegal Fatimata Ly et al.
Table 1. Demographic and clinical characteristics of patients with
scabies who
received BB once or twice, or IV, Dakar, Senegal
Characteristic BB1a
No. (%)
BB2b
No. (%)
IV groupc
No. (%)
Total
No. (%)
P-value
Age, in years
£ 15 47 (69.1) 23 (47.9) 40 (61.5) 110 (60.8) 0.07
> 15 21 (30.9) 25 (52.1) 25 (38.5) 71 (39.2)
Sex
Male 43 (63.2) 28 (58.3) 45 (69.2) 116 (64.1) 0.48
Female 25 (36.8) 20 (41.7) 20 (30.8) 65 (35.9)
Disease duration,d
in weeks
£ 2 17 (27) 13 (28.3) 11 (17.2) 41 (23.7) 0.25
> 2 46 (73) 33 (71.7) 53 (82.8) 132 (76.3)
Superinfection before
randomization
Yes 24 (35.3) 11 (22.9) 19 (29.2) 54 (29.8) 0.35
No 44 (64.7) 37 (77.1) 46 (70.8) 127 (70.2)
No. of sites involved
£ 5 41 (60.3) 30 (62.5) 31 (47.7) 102 (56.4) 0.20
³ 6 27 (39.7) 18 (37.5) 34 (52.3) 79 (43.6)
Parasitological
examination result
Positive 25 (36.8) 21 (43.7) 25 (38.5) 71 (39.2) 0.74
Negative 43 (63.2) 27 (56.3) 40 (61.5) 110 (60.8)
Scabies in family
members
Yes 50 (73.5) 34 (70.8) 44 (67.7) 128 (70.7) 0.76
No 18 (26.5) 14 (29.2) 21 (32.3) 53 (29.3)
No. of family members
with scabies
£ 5 40 (59) 24 (50) 25 (38.5) 89 (49.2) 0.06
> 5 28 (41) 24 (50) 40 (61.5) 92 (50.8)
BB, benzyl benzoate; IV, ivermectin.
a Group that received one application of benzyl benzoate.
b Group that received two applications of benzyl benzoate.
c Group that received ivermectin.
d Disease duration was unknown in some patients.
application of BB; namely, 493 family
members of individuals in the BB1
group, 373 family members of those in
the BB2 group, and 481 family members
of those in the IV group.
The criterion for judging the effectiveness
of treatment was the complete
disappearance of visible lesions and
itching at day 14. Also evaluated were
treatment tolerability and compliance,
which were assessed retrospectively by
questioning the patients. Randomized
patients were followed up every week
until definitively cured (i.e. on days 7,
14, 21 and 28). The groups were also
compared at day 28.
Statistics
The statistical analysis was performed
using Stata 8.0 software (Stata Corp.,
College Station,TX, United States of
America). Both an intention-to-treat
and a per-protocol analysis were performed.
The different treatment arms
were compared using the c² test. Odds
ratios (ORs) were calculated, along
with their 95% confidence intervals
(CIs). We performed a multivariate
analysis which took into account variables
that differed by more than 20%
between groups and variables that had
a potential influence on treatment. The
initial plan was to carry out an intermediate
analysis using the Bonferroni
adjustment when between 150 and 200
patients had been enrolled.
Ethical approval
The study was approved by the ethical
committee of the Senegalese Ministry
of Health and Prevention. A consent
form was signed by all adult patients
enrolled in the trial or by the parents
of enrolled children. The document
was translated into the local language
if necessary. All treatments prescribed
in connection with the study were
provided free of charge, and a sum was
allocated for patients’ transportation
to the study centre for follow-up visits.
Results
We present here the results of an intermediate
analysis that was performed
after 181 patients had been enrolled in
the trial between July 2003 and September
2004: 65 in the IV group, 68
in the BB1 group and 48 in the BB2
group. The trial flowchart is shown in
Fig. 1, and the demographic and clinical
characteristics of the patient groups
are summarized in Table 1.
The male:female sex ratio was
1.78:1, the participants’ mean age was
16.5 years (range: 5–63), and 110 of the
181 patients (60.8%) were aged under
15 years. The mean disease duration was
5.2 weeks (range: 1–20).
Superinfection
was noted in 54 patients (29.8%)
before randomization. The number of
sites affected was £ 5 in 102 patients
(56.4%) and > 5 in the remainder.
Overall, 128 index patients (70.7%)
reported at least one other family member
with scabies, and of these patients,
89% reported more than three family
members affected. The parasitological
examination result was positive in 71
patients (39.2%) and showed Sarcoptes
in 63.4% of the cases, eggs in 33.8%
and faecal pellets in 2.8%. There was
no significant difference before treatment
between the three groups in any
of the following characteristics: age,
sex, disease duration, number of sites
involved, superinfection and number of
family members with scabies (Table 1).
All eight patients who had clearly
worsened clinically at day 7 were in the
IV group; no patient who received BB
required a second course of treatment
at day 7.
By day 14, 19 patients were lost to
follow-up: 8 in the BB1 group and 11 in
the IV group. Three additional patients
were lost to follow-up by day 28 (i.e.
2 in the BB1 group and 1 in the IV
group). Failure to follow the treatment
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Fatimata Ly et al. Treatment of human scabies in Senegal
Table 2. Cure rates at treatment days 14 and 28 in patients with
scabies who received
BB once or twice, or IV, Dakar, Senegal
Treatment No. Day 14 Day 28
Cured
No. (%)
P-value Cured
No. (%)
P-value
BB1a 68 37 (54.4)
< 10–6
52 (76.5)
< 10–5 BB2b 48 33 (68.8) 46 (95.8)
IV groupc 65 16 (24.6) 28 (43.1)
Total 181 86 126
BB, benzyl benzoate; IV, ivermectin.
a Group that received one application of benzyl benzoate.
b Group that received two applications of benzyl benzoate.
c Group that received ivermectin.
Table 3. Results of multivariate logistic analysis of data collected 14
days after
initiating treatment for scabies in randomized controlled trial, Dakar,
Senegal
Variable ORa 95% CI
Two applications of BBb 2.04 0.89–4.66
Oral IVb 0.23 0.10–0.50
Age > 15 years 1.21 0.57–2.56
Parasitology test positive 1.04 0.52–2.08
Compliant with treatment 2.27 1.02–5.03
No. of sites initially involved ³ 6 0.83 0.21–3.19
Superinfection before randomization 1.28 0.61–2.69
No. of family members with scabies > 5 0.70 0.43–1.16
BB, benzyl benzoate; CI, confidence interval; IV, ivermectin; OR, odds
ratio.
a Ratio of the odds of achieving a cure.
b The reference group was composed of patients who received a single
application of BB.
protocol was noted in 32 patients: 29
applied BB either excessively or insufficiently
and 3 took an inadequate
dose of IV. Treatment compliance was
significantly better in the IV group
(P = 0.002). The use of adjunctive treatment
measures was considered correct
in 177 of the 181 patients (97.8%),
and there was no difference between
the treatment groups with respect to
adjunctive measures (P = 0.148). The
level of treatment compliance among
all family members was 82%, and no
difference was noted between treatment
arms (P = 0.7).
Table 2 summarizes the study
findings on the effectiveness of treatment.
At day 14, 86 of the 181 patients
(47.5%) were cured. The cure rate was
higher in the BB2 group (68.8%) than
in either the BB1 group (54.4%) or the
IV group (24.6%), at a level of significance
of P < 10−6 overall. A comparison
of the treatment groups showed that
topical treatment (i.e. BB1 and BB2
groups combined) was superior to
oral IV (P < 10−5). Also at day 28, the
cure rate was higher in the BB2 group
(95.8%) and the BB1 group (76.5%)
than in the IV group (43.1%), with
P < 10−5. An analysis of the subgroup
of patients with parasitologically proven
scabies showed that two applications of
BB resulted in healing in 14 out of 21
patients (66.7%), one application, in
13 out of 25 (52.0%), and IV, in 7 out
of 25 (28.0%), with P = 0.029.
Superinfection occurred during
treatment in 27 of the 181 patients
(15%): 18 of them were in the IV
group, 5 in the BB1 group, and 4 in the
BB2 group. The difference was statistically
significant (P = 0.006).
We also performed a per-protocol
analysis that excluded poorly compliant
patients, those lost to follow up
and those who had received less than
150 μg/kg of IV. The rates of healing
observed were as follows: in the BB2
group, 84% at day 14 and 96% at
day 28; in the BB1 group, 62% at day
14 and 91% at day 28; and in the IV
group, 29% at day 14 and 50% at day
28. Topical treatment was still significantly
better than oral IV (c² = 24.3,
P < 10–5).
Table 3 shows the results of a multivariate
logistic analysis performed
on the data collected at day 14, with
the BB1 group serving as the control
group. The analysis confirmed that
the cure rate was highest in the BB2
group, followed by the BB1 group and
then by the IV group. The OR for a
cure in the BB2 group was 2.04 (95%
CI: 0.89–4.66) and 0.23 (95% CI:
0.10–0.50) in the IV group (Table 3).
Apart from the treatment type, only
good compliance was significantly associated
with a higher cure rate.
At day 28, the 25 patients in the
IV group and the 6 in the BB1 group
who were not lost to follow-up and
who were not cured received two consecutive
applications of BB, while the
2 patients in the BB2 group who were
not cured were given IV. Two weeks
later, all patients had been cured.
Treatment tolerance could be
evaluated in 161 patients. Of these,
37 (23%) had minor adverse effects:
irritant dermatitis in 18 patients in the
BB2 group and 12 in the BB1 group,
and gastrointestinal side effects in the
IV group (abdominal pain in 5 patients
and slight diarrhoea in 2). There was a
statistically significant difference in the
frequency of adverse effects (P = 0.02).
Given the clear difference in effectiveness
between IV and both of
the BB protocols and the significantly
higher risk of superinfection during
treatment in the IV group, the study
was suspended for ethical reasons after
the intermediate analysis.
Discussion
The study showed that topical BB
was more effective for the treatment
of scabies than oral IV, irrespective
of the number of applications of BB.
However, two applications of BB gave
a higher cure rate at day 14 than one
application. BB was so clearly superior
and the rate of superinfection – a risk
factor for post-streptococcal glomerulonephritis
– was so much higher among
patients on IV,3,9 that we suspended the
trial before its planned term. In multivariate
analysis, only good compliance
showed a statistically significant association
with a cure.
Serological testing for HIV was not
required, since the prevalence of HIV
428 Bull World Health Organ 2009;87:424–430 |
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Treatment of human scabies in Senegal Fatimata Ly et al.
Table 4. Results of various therapeutic trials comparing oral IV with
topical treatment for common scabies
Ivermectin Comparison drug n Cure rate (%)
(IV vs comparison drug)
P-value Lost to
follow-up
No. (%)
Reference
100 μg/kg once 10% BB for 12 hours 44 70 vs 48 at 1 month 0.08 0
(0) 12
200 μg/kg once or twicea 5% permethrin in single
overnight application
85 70 vs 98 at 2 weeks
95 vs 100 at 4 weeks
0.0004 0 (0) 13
0.22
150–200 μg/kg once or twicea 1% lindane 53 74 vs 54 at
2 weeks
95 vs 96 at 4 weeks
0.19 10 (19) 14
0.99
200 μg/kg once 1% lindane 200 82 vs 44 at 4 weeks <
10–5 50 (25) 15
200 μg/kg once 10% BB 110 56 vs 51 at 3 weeks 0.69 30 (27) 16
200 μg/kg once 25% BB 58 93 vs 48 at 30 days 0.0002 Unknown 17
200 μg/kg once or twicea 25% BB daily for 3
consecutive days
210 79 vs 59 at 2 weeks
95 vs 86 at 4 weeks
0.003 10 (4) 18
0.04
BB, benzyl benzoate; IV, ivermectin.
a Two weeks after the first dose.
infection in Senegal is below 1%.8 We
assumed that most cases of scabies occurred
in individuals without an HIV
infection. Moreover, the presence of
crusted scabies, which is suggestive of
HIV infection, resulted in exclusion
from the study. We also excluded patients
who used skin bleaching products,
a more commonly observed cause
of skin immunosuppression in our context
and a practice often accompanied
by steroid use.10
We included in the study only
patients whose diagnosis of scabies was
certain in accordance with objective
clinical criteria whose validity has been
established in the same setting. The criteria
were applied by trained observers,6
and if any doubt about the diagnosis
existed, the patient was excluded. Although
the parasitological examination
gave a positive result in only 39% of
cases, a negative result did not preclude
a diagnosis of scabies, since the
sensitivity of this test is known to be
less than 50%, according to previous
studies.11 The low rate of positivity we
found may be explained by the high
frequency (29%) of bacterial superinfection
of the lesions. In any case, the
effectiveness of treatment, whether
IV or BB, was similar in parasitologically
positive and negative patients. We
chose to perform an open study rather
than a double-blind study primarily
for practical reasons but also because
it is recommended in pragmatic trials.
Patients lost to follow up and those
who violated the treatment protocol
were included in an intention-to-treat
analysis. Patients who had clearly worsened
at day 7 received a second course
of treatment identical to that given
the week before. However, it should
be emphasized that only patients in
the IV group received such treatment,
which again provides evidence that
IV is less effective.
Finally, we had
hypothesized a 15% difference in effectiveness
between treatments, and
we found a difference of 29%. The a
posteriori power of our study to detect a
difference between the BB2 group and
the IV group was 96%.
Our results differ noticeably from
the cure rates with IV and BB reported
in the literature. Of seven randomized
trials that compared topical scabicides
to IV,12–18 the four that compared IV
and BB showed that IV was either
an equivalent or a superior treatment
(Table 4). We believe our results differ
from those previously reported for several
reasons. First, defined criteria for
the diagnosis of scabies were applied in
only four of the seven studies, and parasitological
testing of scrapings was also
performed in only four, which suggests
that the diagnosis was unconfirmed in
the others.
Second, although the proportion
of patients lost to follow-up was at
least 19% in three studies, the statistical
analyses were performed under the
assumption that the treatment was as
effective in the patients lost to followup
as in those who were observed at
the study end-points, which is methodologically
incorrect. In contrast, we
used an intention-to-treat analysis.
Third, in four studies the single
effectiveness end-point was assessed
after 21–30 days, later than in our
study. Surprisingly, the effectiveness of
IV observed in our study appeared to be
much higher at day 28 than at day 14,
a result also seen in three other studies
in which effectiveness was evaluated
on two different dates. The only trial in
which IV yielded a significantly higher
cure rate than a topical treatment at day
14 was not randomized.18 In addition,
in that study a cure was defined as the
“absence of pruritus and the absence
of new lesions”, whereas in our study
the disappearance of clinical lesions
was considered necessary. This suggests
there may have been subjectivity in assessing
the presence of a cure. In fact,
we have no clear evidence that the use
of a second dose of IV, as was given to
some patients on day 7 or day 14 of our
study, improved effectiveness. Had we
continued to observe patients without
giving them any additional treatment,
the final effectiveness rate obtained with
IV may have been higher. We did not
choose this approach for ethical reasons,
since the risk of superinfection made it
essential to act as quickly as possible.
Fourth, 57.1% of the patients in
our study had more than five affected
sites and could thus be considered as
having severe disease. It is possible that
IV is more effective in milder cases of
scabies, although the statistical analysis
we performed did not provide any supporting
evidence.
Fifth, the effectiveness of the topical
treatments that were compared with
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Fatimata Ly et al. Treatment of human scabies in Senegal
Résumé
Comparaison entre l’ivermectine et le benzoate de benzyle en
une ou deux applications dans le traitement de
la gale humaine à Dakar au Sénégal :
essai contrôlé randomisé
Objectif Comparer l’efficacité de
l’ivermectine par voie orale (IV) et
du benzoate de benzyle (BB) administré par voie topique
selon deux
modalités pour traiter la gale dans un contexte
communautaire.
Méthodes L’essai a porté sur des
individus de 5 à 65 ans atteints
de gale, qui s’étaient
présentés au service de dermatologie de
l’Institut d’Hygiène Sociale de Dakar au
Sénégal. L’essai ouvert
randomisé a comparé trois traitements : une
application unique
de BB à 12,5 % sur 24 heures (groupe BB1), deux applications
de BB, chacune sur 24 heures (groupe BB2), et une prise d’IV
par
voie orale, à raison de 150-200 μg/kg (groupe IV).
La
principale
mesure de résultat était la disparition des
lésions cutanées et des
démangeaisons au 14e jour. En cas de
nécessité, le traitement était
renouvelé et les patients étaient
évalués jusqu’à ce
qu’ils soient
guéris. Les résultats ont
été analysés en intention de traiter.
Une
analyse intermédiaire planifiée à
l’avance a été effectuée
après
recrutement de 68, 48 et 65 patients dans les groupes BB1, BB2
et IV respectivement.
Résultats Au 14e jour, 33 patients (68,8 %) du groupe BB2
étaient guéris contre 37 (54,4 %) du groupe BB1
et 16 (24,6 %)
du groupe IV (p < 10–6). Les surinfections
bactériennes étaient
plus fréquentes dans le groupe IV que dans les groupes BB1
et
BB2 pris collectivement (28 % contre 7,8 % respectivement,
p = 0,006).
Au 28e jour, 46 patients (95,8 %) du groupe BB2
étaient
guéris contre 52 (76,5 %) du groupe BB1 et 28 (43,1 %) du
groupe
IV (p < 10–5). Ces résultats clairs nous
ont incités à interrompre
précocement l’étude.
Conclusion Le benzoate de benzyle sous forme topique s’est
révélé clairement plus efficace que
l’ivermectine par voie orale
pour le traitement de la gale dans une communauté
sénégalaise.
Resumen
La ivermectina frente al benzoato de bencilo aplicado una o dos veces
como tratamiento de la sarna humana
en Dakar, Senegal: ensayo aleatorizado controlado
Objetivo Comparar la eficacia de la ivermectina (IV) oral y de dos
posologías de benzoato de bencilo (BB) tópico
como tratamientos
de la sarna en un entorno comunitario.
Métodos El ensayo abarcó a pacientes de 5 a 65
años con sarna
que acudieron al departamento de dermatología del Instituto
de
Higiene Social de Dakar, Senegal. Aleatorizado y abierto, este
ensayo estudió el efecto de tres tratamientos: una
aplicación única
de BB al 12,5% durante 24 horas (grupo BB1), dos aplicaciones
de BB, cada una de 24 horas (grupo BB2), y IV oral, 150–200
μg/
kg (grupo IV).
El criterio principal de valoración fue la
desaparición
de las lesiones cutáneas y el prurito al día 14.
En caso necesario,
se repetía el tratamiento y se evaluaba a los pacientes
hasta
que estuviesen curados.
Los resultados se sometieron a
análisis
por la intención de tratar. Se llevó a cabo un
análisis intermedio
preplanificado en un momento en que los grupos BB1, BB2 y IV
contaban con 68, 48 y 65 pacientes, respectivamente.
Resultados El día 14 se habían curado 33
pacientes (68,8%)
en el grupo BB2 frente a 37 (54,4%) en el grupo BB1 y 16
(24,6%) en el grupo IV (p < 10–6). Los casos de
sobreinfección
bacteriana fueron más frecuentes en el grupo IV que en los
grupos
BB1 y BB2 combinados (28% frente a 7,8%, respectivamente;
p = 0,006). El día 28 se habían curado 46
pacientes (95,8%) del
IV in previous studies appears to be
unexpectedly low. Thus, it is possible
that they were not used optimally.
In our study, time was allocated to a
thorough explanation of how BB should
be applied. Moreover, our multivariate
analysis yielded a significant association
between good compliance and a cure.
>
Finally, there are possible pharmaceutical
explanations for IV’s relatively
low effectiveness in our trial. It has been
reported that Sarcoptes scabiei has developed
at least partial resistance to IV,19
and IV has previously been used for
the mass treatment of onchocerciasis
in Senegal.20 In addition, some authors
have suggested low effectiveness in
children, who constituted the majority
of our sample, because excretion of IV
is reduced in subjects with a low physiological
rate of sebum production.21
Conclusion
In our controlled trial, topical 12.5%
BB was more effective and safer – particularly
in light of the lesser risk of
secondary superinfection – than oral
IV for the treatment of common scabies
in Dakar. Moreover, in developing
countries like Senegal, economic considerations
are important in the treatment
of common disorders like scabies
because there is often a need to treat
large families. In our study, 51% of
the patients had more than five affected
family members.
Since the difference in
effectiveness obtained by applying BB
once or twice was relatively modest,
we recommend a single application
rather than two as the standard first-line
treatment for common scabies, with
a second application prescribed only
when there is treatment failure.
The
current cost of treating one person with
scabies with a generic form of BB is approximately
€ 0.1 (less than 20 United
States cents). ■
Acknowledgements
We thank Pape N’Diaye, Binta Ndoye,
Fatimata Kounta and Mbayang Pouye
Sene for technical assistance during the
study, and Roderick Hay for reading
the manuscript.
Funding: This study was supported by
a grant from the Société Française de
Dermatologie Pédiatrique.
Competing interests: None declared.
430 Bull World Health Organ 2009;87:424–430 |
doi:10.2471/BLT.08.052308
Research
Treatment of human scabies in Senegal Fatimata Ly et al.
grupo BB2, frente a 52 (76,5%) del grupo BB1 y 28 (43,1%) del
grupo IV (p < 10–5).
La gran significación
de estos resultados llevó
a interrumpir el estudio antes de lo previsto.
Conclusión La aplicación tópica de BB
fue claramente más eficaz
que la IV oral como tratamiento de la sarna en una comunidad del
Senegal.
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