Abstract

Background

Scabies, caused by Sarcoptes scabiei variety hominis or the human itch mite, is a common parasitic infection. While anyone can become infected, it causes significant morbidity in immunocompromised hosts and it spreads easily between human hosts where there is overcrowding or poor sanitation. The most common symptom reported is itch which is worse at night. As the symptoms are attributed to an allergic reaction to the mite, symptoms usually develop between four to six weeks after primary infection. Therefore, people may be infected for some time prior to developing symptoms. During this time, while asymptomatic, they may spread infection to others they are in close contact with. Consequently, it is usually recommended that when an index case is being treated, others who have been in close contact with the index case should also be provided with treatment.

Objectives

To assess the effects of prophylactic interventions for contacts of people with scabies to prevent infestation in the contacts.

Search methods

We searched electronic databases (Cochrane Occupational Safety and Health Review Group Specialised Register, CENTRAL (The Cochrane Library), MEDLINE (Ovid), Pubmed, EMBASE, LILACS, CINAHL, OpenGrey and WHO ICTRP) up to November 2013.

Selection criteria

Randomised controlled trials (RCTs) or cluster RCTs which compared prophylactic interventions which were given to contacts of index cases with scabies infestation. Interventions could be compared to each other, or to placebo or to no treatment. Both drug treatments and non‐drug treatments were acceptable.

Data collection and analysis

Two authors intended to extract dichotomous data (developed infection or did not develop infection) for the effects of interventions and report this as risk ratios with 95% confidence intervals. We intended to report any adverse outcomes similarly.

Main results

We did not include any trials in this review. Out of 29 potentially‐relevant studies, we excluded 16 RCTs as the data for the contacts were either not reported or were reported only in combination with the outcomes for the index cases. We excluded a further 11 studies as they were not RCTs. We also excluded one study as not all subjects were examined at baseline and follow‐up, and another as it was a case study.

Authors' conclusions

The effects of providing prophylactic treatments for contacts of people with scabies to prevent infestation are unknown. We need well‐designed RCTs of the use of prophylactic measures to prevent the transmission of scabies conducted with people who had the opportunity for prolonged skin contact with an index case, such as family members, healthcare workers or residential care personnel, within the previous six weeks.

Author(s)

Deirdre FitzGerald, Rachel J Grainger, Alex Reid

Abstract

Plain language summary

Interventions for preventing the spread of infestation in close contacts of people with scabies

Background

Scabies is a common parasitic infection. It is caused by a mite, Sarcoptes scabiei variety hominis, also known as the human itch mite, which depends on humans to survive. Crusted scabies (or Norwegian scabies) is caused by the same mite, but tends to occur in people whose immune system is not working so well, such as transplant patients on immunosuppressive therapy, people who misuse alcohol, or other debilitated people. Scabies infection spreads from person to person by skin contact. This is why it is more prevalent in areas with poor sanitation or overcrowding. In high‐income countries it tends to spread between family contacts, between people in residential care, or between patients and staff in hospitals. People may be infected with these mites for several weeks before developing symptoms. During this time it is possible to spread the infection to other people. Consequently people who are in contact with suspected cases of scabies infection are often given preventative treatments in an attempt to stop the development of symptoms. Preventive treatment also aims to prevent further spread of the infection and to prevent the person who was the source of infection from getting reinfected. This review is important, as before conducting this review we were unable to say if using preventive treatment helps or not.

What does the research say?

We searched for studies in which people who had been in contact with scabies‐infected people had been given medical treatment, or had been advised about personal hygiene to prevent the scabies infection from spreading. We also wanted studies to have been designed so that the treatment received by participants (either medication or advice) was determined by chance. We did not find any studies fulfilling these criteria.

Conclusions

There is currently no evidence to say if treating or advising people who have been in contact with scabies‐infected people is effective in preventing the spread of scabies infection. We need researchers to conduct studies with people who may have been in skin contact with a person who has been diagnosed with a scabies infection within the previous six weeks. Half of these people should be given preventive treatment and the other half something else. Who gets what should be determined by chance so that the two groups are truly similar in every respect except the treatment they receive.

Author(s)

Deirdre FitzGerald, Rachel J Grainger, Alex Reid

Reviewer's Conclusions

Authors' conclusions 

Implications for practice 

Based on the currently available data, this systematic review can provide no recommendations about the use of treatment for close contacts of people with scabies to prevent either infestation, reinfection in the index case or onward transmission to other contacts.

Implications for research 

There is a need for well‐designed randomised controlled trials (RCTs) to provide conclusive evidence on the use of prophylactic measures to prevent the transmission of scabies.

Studies should recruit people who had been in contact with an index case with scabies infestation within the previous six weeks. All people who had substantial opportunity for prolonged skin to skin contact with the index case should be included, e.g. family members, healthcare workers or residential care personnel responsible for personal care of the index case, close friends where the index case is a child, other residents in nursing homes or residential care environments. Given that symptoms of infestation generally develop within the first six weeks after transmission of scabies, there is likely to be little clinical benefit in recommending prophylaxis for contacts of index cases who have not developed symptoms at six weeks after the exposure; therefore contacts who were exposed to an index case greater than six weeks previously should not be included in studies designed to examine any benefit of prophylaxis.

The diagnosis of the index case should be made by a physician, or other suitably‐qualified healthcare professional, in those with symptoms suggestive of infection (e.g. itch that is worse at night), and either a positive dermatological examination (burrows, papules, vesicles), or a positive microscopic parasitological examination. The contacts of the index case should also be examined similarly to exclude the presence of undiagnosed infection in the study participants at the start of the study period. Study participants who have been diagnosed with scabies or who have been treated for scabies infection within the previous three months should be excluded, as it would not be possible to distinguish between a new transmission and treatment failure.

The extent and type of contact between the index case and the study participants should be defined in advance of the start of the study and clearly described in the study protocol. For all study participants, the exposure type and duration should be accurately recorded. Potential study participants who do not meet these pre‐defined exposure criteria should be excluded from the study. Given that durations and types of exposure are likely to vary considerably in different populations (i.e. between family members, in hospitals or residential care facilities, between colleagues), separate studies will be required to determine the implications for prophylaxis accordingly.

Studies should randomise participants, either individually or in clusters, to receive either prophylactic intervention, alternative intervention or placebo. In settings where contacts could have close contact with each other (and therefore provide an opportunity for transmission between contacts), e.g. contacts of index cases in family settings, a cluster randomised controlled design would be more appropriate than randomising individual contacts to different interventions.

Prophylactic interventions should consist of one or more of the following components: medical treatment (with specified type, dose, and regimen); barrier precautions (including patient isolation, patient cohorting, etc.); personal hygiene measures (including hand washing), or environmental decontamination (including advice to wash clothing and bedding).

The effect of the intervention should be measured as the incidence of scabies within eight weeks of being recommended to use the prophylactic treatment. Diagnosis of scabies in the contacts should be based on the clinical opinion of a physician or other suitably‐qualified health professional, on the basis of the development of clinical symptoms suggestive of scabies and either positive physical examination findings or positive microscopy. If contacts were examined more than eight weeks after using the prophylactic intervention, there is an increased chance that other exposures may have occurred in the intervening period and it would not be possible to distinguish between transmission from the first exposure (of interest) and transmission any subsequent exposures. Outcomes in index cases should be reported separately from outcomes in the contacts of the index cases. Adverse outcomes associated with the intervention, such as side‐effects attributed to medication, should be recorded, as should compliance with the recommended treatment.

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