Clinical trial NCT04205669
Conditions: Scabies Households
Sponsor: Centre de Recherche Médicale de Lambaréné
Start date: 2018-10-04; Completion date: 2019-02-21
Enrollment: 104 participants; Allocation: RANDOMIZED; Intervention model: PARALLEL

Brief summary:
It is unclear whether individual treatment of scabies is similarly effective compared to household treatment. This study therefore compares these two treatment strategies with topical benzyl benzoate for treating scabies in Lambaréné and surroundings in Gabon.

Subjects presenting with uncomplicated scabies are randomized into either the Individual Treatment group, where only the affected subjects receive treatment, or the Household Treatment group, where all family members are treated in parallel to the affected subjects regardless of signs and symptoms. The primary endpoint is clinical cure after 28 days; the secondary endpoint is the proportion of affected household members per household after 28 days.

Detailed description:

Arms: arm 1: None arm 2: None
Interventions: intervention 1: Benzyl Benzoate 25% Topical Application Lotion
Intervention descriptions: intervention 1: Applied to skin for the treatment of scabies

Protocol documents:
Prot_SAP_000.pdf: 
 
1 
 
 
 
Individual vs. Household Treatment for 
Scabies or “gratti gratta” in the population 
of Lambaréné and surroundings in Gabon 
 
 
 
 
 
 
 
 
Sponsor: Michael Ramharter, MD, Prof. 
Principal Investigator: Ghyslain Mombo Ngoma, MD, MSc, PhD 
Co-Principal Investigator: Julian Matthewman, MD 
 
Investigators: 
Rella Zoleko Manego, MD 
Lia Betty Dimessa Mbadinga, MD 
Malik Azeez Akinosho, MD 
Christian Haedrich 
Ruth Johanna Kreuzmair 
 
 
Version Number: GrattiGratta31082018 
 


 
2 
Table of Contents 
Introduction (Background) ......................................................................................................... 3 
Research question ......................................................................................................................................... 4 
Study Objectives (Aims) ............................................................................................................. 4 
Primary objectives ........................................................................................................................................ 4 
Secondary objectives .................................................................................................................................... 4 
Endpoints .................................................................................................................................. 4 
Primary Endpoint .......................................................................................................................................... 4 
Secondary Endpoint ...................................................................................................................................... 4 
Methods and Materials .............................................................................................................. 5 
Study Population ........................................................................................................................................... 5 
Sample size ................................................................................................................................................... 5 
Scabies Diagnosis and Data Collection .......................................................................................................... 5 
Study treatment and follow up ..................................................................................................................... 6 
Safety ........................................................................................................................................ 6 
Ethical Considerations ................................................................................................................ 6 
Data ........................................................................................................................................... 7 
Funding ...................................................................................................................................... 7 
Bibliography .............................................................................................................................. 8 
Annex 1: CONSENTEMENT ÉCLAIRÉ .................................................................................. 10 
Annex 2: CONSENTEMENT ÉCLAIRÉ pour le traitement familial ........................................ 12 
 
 
 


 
3 
Introduction (Background) 
Scabies, a contagious skin infestation caused by the mite Sarcoptes scabiei, of which the most 
common symptoms are itching and rash, remains a big health issue in the developing world. 
Major health implications include pyoderma and renal and heart disease, due to secondary 
bacterial infections. Furthermore, managing the disease can come at significant cost to health 
care systems(1,2). Children are the most affected group in the developing world(3).  
There is no exhaustive data on Scabies prevalence in Gabon, however one can assume that it 
is endemic as in other tropical regions(1). The hot and humid climate, often poor sanitation 
and many family members living in the same house are all factors that favor high scabies 
prevalence. One study assessing the prevalence of skin diseases among school children in 
Gabon found a low prevalence of scabies, which stands in contrast to other studies(4). 
Some studies, mostly conducted in the developed world, suggest a cyclical epidemiology of 
Scabies, stating cycle lengths of 15-30 years(5–7). However according to a recent review by 
Hay et al., observed fluctuations are most likely multifactorial, being related to factors such 
as wartime, overcrowding, and climatic changes, with herd immunity playing a limited 
role(1). No literature was found on epidemic cycles in Gabon. 
The clinical presentation of scabies has been previously described in other tropical regions. A 
recent study conducted in Yaoundé showed lesions were most commonly present in the infra-
gluteal folds, on the wrists and in the intergluteal folds. Types of lesions were also 
documented, with crusty lesions being the most common type(8).  
For persons never before affected by scabies it can take up to 6 weeks for symptoms to begin, 
while the mites can already be spread during this asymptomatic period. However in 
reinfestation symptoms usually occur much earlier(1-4 days)(9). 
There exist different agents for the treatment of Scabies with comparable efficacy(10–12). 
Ivermectin seems to be most effective for large populations with high prevalence of 
scabies(10). However the use of ivermectin can lead to serious adverse events in patients with 
high concentration of  Loa Loa microfilariae in the blood(13). Since Loa Loa is endemic in 
Gabon(14), treatment with ivermectin for Scabies should only be given if high Loa 
parasitemia can be excluded. Furthermore, only limited safety data exists for children under 5 
years of age or weighing less than 15 kg, a group in which scabies is common(9). 
Permethrin is the first line topical treatment for Scabies, however it comes at a higher cost per 
treatment, and is more difficult to obtain in Gabon than Benzyl Benzoate, a substance which 
also offers good efficacy and safety(10–12). 
It is recommended that the contact persons of an affected individual shall also be treated at 
the same time, to ensure long term success of treatment, prevent reinfestation and infestation 
of contact persons(9,10,15). However this recommendation lacks a solid background of 
evidence. A recent review concluded that the effects of treating contact persons to prevent 
new infestation are unknown(16). 
There is currently an outbreak of itching lesions suggestive of scabies in Gabon that the local 
population has named “gratti gratta” but there has been so far no raised attention from the 
local medical scientific community to describe these lesions and definitely attribute the 
diagnosis of scabies and sensitize the population in measure for the control of the epidemic.  


 
4 
Research question 
We propose a randomized controlled trial comparing treatment of only affected persons 
presenting at our medical research center (which we will call individual treatment) to 
treatment of the entire household (which we will call household treatment), with both groups 
using the same treatment regimen with benzyl benzoate. We hereby aim to assess the practice 
of systematically recommending household treatment and if it provides a benefit for the index 
case by preventing reinfestation. 
We will also assess the number of household members affected 4 weeks after treatment, by 
examining all household members that are present on the day of the visit. Since the presence 
of itching and skin lesions in a household with a diagnosed scabies case is known to be 
highly specific (15,17), we will also assess the number of probable scabies cases per 
household before and after treatment according to the judgment of the household responsible 
person. Cases identified this way will be defined as “probable” and cases identified through 
clinical diagnosis by a physician will be defined as “confirmed”. 
We will further assess clinical characteristics of Scabies and demographic factors associated 
with its appearance in Lambaréné, Gabon, and surroundings. Although similar studies have 
been conducted elsewhere, little is known about Scabies in Gabon. A better understanding of 
the demographic profile of persons affected by the disease can benefit future control of the 
disease.  
 
Study Objectives (Aims) 
Primary objectives 
To compare the effectiveness of individual vs household treatment for persons affected by 
scabies. 
Secondary objectives 
To compare the effectiveness of individual vs household treatment in terms of proportion of 
household members affected after 4 weeks. 
To describe the clinical presentation of scabies and demographic profiles of persons affected 
presenting at our medical research center in Lambaréné, Gabon. 
To assess the tolerability and safety of benzyl benzoate. 
Endpoints 
Primary Endpoint 
The primary efficacy outcome will be clinical cure after 4 weeks. 
Secondary Endpoint 
Secondary endpoints will include the rate of probable and confirmed scabies cases per 
household after 4 weeks. 


 
5 
 
 
Methods and Materials 
Study Population 
The study will be conducted at the Centre de Recherches Médicales de Lambaréné 
(CERMEL). Cases will be identified from patients presenting at the medical research center, 
which are mostly patients form screening activities conducted for malaria trials. All 
household members that present at the medical research center from a household with at least 
one case of scabies will be included. The first affected subject included of a household will 
be defined as the index case. 
 
Sample size 
Estimating a cure rate of 70% and 95% for individual vs. family treatment respectively we 
calculated a sample size of 35 affected subjects per group to provide a power of 80% with an 
alpha of 0,05. 
When estimating that on average one additional household member affected will present at 
the medical research center alongside an index case, we will aim to include at least 35 
different households. 
 
Scabies Diagnosis and Data Collection 
Subjects will be checked for lesions typical of scabies by a physician. The diagnosis of 
scabies will be made by clinical examination, a method of diagnosis which has been used in a 
number of other studies to diagnose scabies and has been shown to be highly sensitive and 
specific. Scabies will be defined as the presence of itching together with typical distribution 
of lesions, such as on the hands, wrists, elbows, axillae, knees, buttocks, genitalia in men, 
breast areolae in women, palms and soles in children under the age of two(18,19). 
The lesions will be described in terms of location and spread on the body, itching and 
superinfection. A severity scale will be used classifying the cases into mild, moderate, severe 
and crusted according to the number of lesions counted. Photos of characteristic lesions and 
lesions of special interest will be taken. In case of lesions of unclear origin images will be 
assessed via a telemedical consultation by a dermatologist at the department of tropical 
medicine, Berhard Nocht Institute of Tropical Medicine, Hamburg, Germany and a 
recommendation on treatment will be given. Images will be sent pseudonymized to protect 
subject privacy. 
In the course of this study we will assess the use of a low-cost videomicroscope for the 
diagnosis of scabies, a method which has previously shown promise as a cost-effective way 
to definitely attribute lesions to scabies infestation(20). Thus, all patients will be examined 
with such a videomicroscope. 
Demographic data including age, sex and household size will be assessed. 


 
6 
Study treatment and follow up 
For the treatment part of this study index cases will be randomized in either of two groups 
and subjects of the respective household will follow the randomization outcome of the index 
case. Randomization will be done in RedCAP. In the first group only subjects affected by 
scabies shall be treated. In the second group all persons living in the same household as the 
index case shall be treated, and treatment will be dispensed according to the number of 
household members stated by the household responsible person. For both groups the choice 
of treatment will be a single application of benzyl benzoate 25%, which shall be mixed with 
an equal quantity of water for older children and with 3 parts of water for infants. Subjects 
will be instructed on the use of the treatment and given a standardized leaflet with 
instructions, however the use of the treatment will not be supervised, making this an 
intervention conducted in a real world setting. 
Subjects will be followed up after 4 weeks. At follow up visits the subjects will be questioned 
about the symptoms of scabies and any adverse events experienced and examined by a 
physician. Cure will be defined as the clinical improvement in lesions with no new lesions. 
All household members present at this visit will also be examined for scabies. Subjects and 
household members considered not cured or newly infested will be treated.  
 
 
Safety 
 
Benzyl Benzoate is generally safe to use for all persons, including infants and pregnant 
women. It is contraindicated only for persons with known hypersensitivity to benzyl 
benzoate, which will constitute an exclusion criterium. Adverse events include skin irritation 
and stinging sensation(21). In case of accidental ingestion subjects are requested to contact 
the principal investigator. 
 
 
Ethical Considerations 
To maintain randomization into the individual and household treatment groups and to avoid 
preferential withdrawal, loss to follow up, or spillover effects the informed consent process 
will be performed in a two step approach.  
First all participants and/or parents/guardians (as applicable) shall be informed about all 
aspects of this clinical trial including the study medication. However, the respective 
intervention strategies (individual versus household treatment) will not be disclosed to the 
participants in the first step of the informed consent process. After randomization, only for 
the household treatment group, a person responsible for the household shall be informed 
about and agree to the treatment of the entire household. 
The study will be conducted according to the ethical principles stated in the Declaration of 
Helsinki, the applicable guidelines for ICH-GCP, and the applicable laws and regulations of 
Gabon. Approval from the CERMEL ethics review committee will be acquired. The study 
will conducted in compliance with the study protocol. 
 


 
7 
Data 
Data will be collected electronically in RedCAP using the online interface and the RedCAP 
mobile app for offline data collection. 
 
Funding 
The trial will be institutionally funded by the Department of Clinical Research, CERMEL 
and the Bernhard Nocht Institute. 
 
 


 
8 
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