Knowledge and management of scabies in general practitioners and dermatologists

ARTICLE

Auteur(s) :, Hilde Lapeere¹, Lieve Brochez¹, Jozef De Weert¹, Inge Pasteels², Jan De Maeseneer², Jean-Marie Naeyaert^1,*

¹Department of Dermatology, University Hospital Ghent, De Pintelaan 185, 9000 Ghent, BelgiumFax: (+32)9 2404996.
²Department of General Practice and Primary Health Care, Ghent University. De Pintelaan 185, 9000 Ghent, Belgium

accepté le 15 Decembre 2005

Materials and methods

The knowledge questions were categorized into 5 topics involving the biology, incubation period and transmission, diagnosis and treatment of scabies, and Norwegian scabies. The questions were of the ‘true or false’ and ‘single best response’ type. One point was given for a correct answer; no points were subtracted for wrong answers or blanks. The maximum score that could be obtained was 39 points.

The questionnaire was tested in a small group of resident dermatologists at the University Hospital of Ghent. GPs and dermatologists from the region of Ghent were invited to participate in this anonymous survey during a scientific meeting in 2003. The investigator ran over the questions together with the participants.

The Mann-Whitney U test was used for analysis of the differences between GPs and dermatologists on treatment preferences and hygienic advice.

Because the scores on the knowledge test were not normally distributed, a cumulative logit model was used to examine the effect of three independent variables, namely profession, number of years of experience and the estimated number of scabies patients per year, on the score obtained on the knowledge test. The cumulative logit model can handle multi category responses. The parameters found in this model give the effect of each factor separately but controlled for the other independent variables included in the model.

P values below 0.05 were regarded as statistically significant. Basic statistical analysis was performed using SPSS 11.0 [14] and the cumulative logit model was obtained in SAS^® release 8.2 [15].
Table 1 English translation of the questionnaire

Results

Eighty two percent of the GPs had more than 10 years of practice in contrast to only 43% of the dermatologists.

Dermatologists estimated seeing more scabies patients per year than GPs. Sixty-eight percent of the dermatologists estimated seeing six or more scabies patients per year compared to 29% of the GPs.

About 40% of the dermatologists and 55% of the GPs answered that they rarely or never reported a patient with scabies to the Health Inspection.

The median score on the knowledge test of all physicians was 29/39 (74%). The lowest median score was for the item biology (3/6 or 50%) and the highest median score was for the item transmission and incubation (6/7 or 86%) ( (figure 1) ).

When incorporated in the cumulative logit model, profession, number of years of experience and estimated number of patients all had a statistical significant effect on the score on the knowledge test (table 2)( Table 2 ). The odds of obtaining a higher score are 12.5 times higher in dermatologists than in GPs. Similarly the odds of obtaining a higher score are 1.51 times higher per increasing category of practice experience and 1.69 times higher per increasing category of the estimated number of scabies patients.

Permethrin cream is prescribed by more than 90% of both dermatologists and GPs. Only 20% of those prescribing permethrin make compounded prescriptions. For about half of the dermatologists and GPs, permethrin cream is the only treatment prescribed for scabies, meaning they do not prescribe concomitant medication. Ivermectin tablets are prescribed by 24% of the dermatologists whereas none of the GPs had ever prescribed this drug (table 3)( Table 3 ).

Finally the hygienic advice given by dermatologists and GPs was similar. All of the dermatologists and GPs advise their patients either to wash all their clothes and linen or to keep it in a plastic bag. Thirty-five percent of the GPs and 9% of the dermatologists advised mopping or disinfecting the bedroom and/or living room (P < 0.001).
Table 2 Results of the cumulative logit model

Discussion

The total scores on knowledge about scabies were of an acceptable level in both dermatologists and GPs. The median score was lowest for the items biology and Norwegian scabies. Basic knowledge about these items is important because of the implications for treatment, transmission and prevention. Scabies is caused by S. scabiei var. hominis. The female mite makes burrows in the stratum corneum and granulosum of the skin in which the eggs are laid. The incubation period for scabies is 1 to 6 weeks, meaning that patients can already be infested before they notice any clinical sign or symptom [6]. Scab mites strongly depend on the warm and humid environment of their host. They can survive outside the host for about 36 hours [5]. The scab mite is also host specific, meaning that other variants (e.g. var canis in dogs) do not cause scabies in humans. These animal variants can be responsible for a temporary skin eruption in humans that is, however, clinically different from scabies. Scabies in humans is mainly transmitted by bodily contact with another scabies patient and not by pets. Norwegian scabies occurs when patients are infested with thousands of mites. This type of scabies is also caused by S. scabiei var. hominis and presents clinically with thick psoriasiform crusts on hands and feet and nail dystrophy. Norwegian scabies can occur in immune compromised patients (e.g. HIV patients) or in patients with decreased itch sensation (e.g. dementia) [6].

The score on the knowledge test was influenced by profession, number of years of experience and the estimated number of scabies patients.

Physicians (GPs as well as dermatologists) who see more scabies patients have more experience with the disease and therefore know more about scabies than physicians who see less scabies patients. However, it is also possible that physicians with lower test scores do not recognize scabies when confronted with the disease and therefore estimated seeing fewer patients than their colleagues with higher test scores. The same explanation could account for the observation of the higher score in the knowledge test in physicians with more practice experience.

Finally dermatologists obtained a higher score than GPs. Several factors could account for this difference, eg scabies will probably be more frequently discussed in the scientific literature or meetings for dermatologists than for GPs.

About 40% of the dermatologists and 55% of the GPs admit that they rarely or never report scabies patients to the Health Inspection. This proportion could be even higher in daily practice because participating physicians could have been biased to give an answer that is socially acceptable (social desirability bias) [17].

Permethrin cream is by far the most popular treatment for scabies; more than 90% of the dermatologists and GPs prescribe this treatment. Permethrin cream is currently considered as the standard treatment for scabies [8]. It should be applied at least once over the total body from the jaw line downwards. In children and bedridden patients the scalp should also be treated [6]. The commercially available product is however expensive in Belgium. Another option is a compounded prescription, which is about 50% cheaper. A compounded prescription is a product prepared by the pharmacist according to the order of the prescribing physician. In our survey only 1 in 5 physicians prescribing permethrin considered the compounded prescription. It is important that all possible contact persons are treated at the same time, even if they do not have symptoms [13]. The cost of treatment, often for several persons, is important for patients and might influence their compliance.

The efficiency of ivermectin in the treatment of scabies has recently been described in the literature [9, 13, 18-20]. In our sample of physicians it was only occasionally prescribed by dermatologists. Ivermectin is not registered in Belgium and physicians who want to prescribe this medication have to fill in special forms along with the classic prescription. Furthermore, the local pharmacist can only order ivermectin in France or Holland. This probably explains why it is primarily prescribed in secondary health care by dermatologists.

In the classic forms of scabies, the patient is infested with a low number of scab mites. Clothes and linen can contain viable parasites and should be washed at 60 °C or separated in plastic bags for 2 or 3 days. It is unlikely that mites are spread in the environment of the patient [13]. Furthermore, the mite’s chances of survival are limited once they get separated from their host [6]. Therefore it is generally accepted that it is not necessary to clean or disinfect the house, furniture, carpets, etc. [5]. In the current survey about 33% of the GPs and 9% of the dermatologists advise their patients to clean or disinfect bedrooms or living rooms. A reason for this could be that GPs are less familiar with the mite’s biology and transmission. In Norwegian scabies, which rarely occurs, patients are infested with millions of mites that are shed in the environment. Special isolation measures, cleaning and disinfection of the environment are appropriate in those cases [6].

This survey was done with a self-constructed questionnaire that was not validated before use. However it was not the intention to develop a universal instrument to test knowledge and practice of scabies but rather to explore the knowledge on the current insights in scabies and to identify a need for education programs in local GPs and dermatologists.

The physicians participating in this survey were attending a scientific meeting and knew about the scabies survey. The dermatologists came from a large region in Flanders while the GPs were all from the region of Ghent. This difference could have an effect on the results. It is also possible that responders tend to give answers that put them in a positive light, even though the survey was anonymous. These factors could have influenced the results of the questionnaire.

Nevertheless, these results can give some idea of the way GPs and dermatologists in Belgium manage scabies.

Acknowledgements

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