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