Research Article: Scabies and Bacterial Superinfection among American Samoan Children, 2011–2012

Date Published: October 12, 2015

Publisher: Public Library of Science

Author(s): Laura Edison, Amanda Beaudoin, Lucy Goh, Camille E. Introcaso, Diana Martin, Christine Dubray, James Marrone, Chris Van Beneden, Martyn Kirk.

http://doi.org/10.1371/journal.pone.0139336

Abstract

Scabies, a highly pruritic and contagious mite infestation of the skin, is endemic among tropical regions and causes a substantial proportion of skin disease among lower-income countries. Delayed treatment can lead to bacterial superinfection, and treatment of close contacts is necessary to prevent reinfestation. We describe scabies incidence and superinfection among children in American Samoa (AS) to support scabies control recommendations.

We reviewed 2011–2012 pharmacy records from the only AS pharmacy to identify children aged ≤14 years with filled prescriptions for permethrin, the only scabicide available in AS. Medical records of identified children were reviewed for physician-diagnosed scabies during January 1, 2011–December 31, 2012. We calculated scabies incidence, bacterial superinfection prevalence, and reinfestation prevalence during 14–365 days after first diagnosis. We used log binomial regression to calculate incidence ratios for scabies by age, sex, and county. Medical record review identified 1,139 children with scabies (incidence 29.3/1,000 children aged ≤14 years); 604 (53%) had a bacterial superinfection. Of 613 children who received a scabies diagnosis during 2011, 94 (15.3%) had one or more reinfestation. Scabies incidence varied significantly among the nine counties (range 14.8–48.9/1,000 children). Children aged <1 year had the highest incidence (99.9/1,000 children). Children aged 0–4 years were 4.9 times more likely and those aged 5–9 years were 2.2 times more likely to have received a scabies diagnosis than children aged 10–14 years. Scabies and its sequelae cause substantial morbidity among AS children. Bacterial superinfection prevalence and frequent reinfestations highlight the importance of diagnosing scabies and early treatment of patients and close contacts. Investigating why certain AS counties have a lower scabies incidence might help guide recommendations for improving scabies control among counties with a higher incidence. We recommend interventions targeting infants and young children who have frequent close family contact.

Partial Text

Scabies is an intensely pruritic, highly contagious skin infestation caused by the arachnid mite Sarcoptes scabiei variant hominus. Scabies was added to the World Health Organization’s list of neglected tropical diseases (http://www.who.int/neglected_diseases/diseases/scabies/en/) in November 2013 because it accounts for a substantial proportion of skin disease among low-income countries, and despite the substantial burden of disease, it has been largely absent from the global health agenda [1,2]. The addition of scabies to this list increases publicity for this largely ignored disease and recognizes that new programs are needed to control scabies and its sequelae [1,2]. The highest rates of scabies are reported among children from low-income countries where the prevalence typically ranges from 0.2% to 24%; however, it is endemic among tropical regions, with prevalence ranging from 10% to 25%, and areas in the Pacific region have reported prevalence as high as 50% [1,3–11]. Although the incidence of scabies has not been determined previously in American Samoa, a 2009 study of 8,767 children in western Samoa reported a prevalence of 4.3%, whereas a prospective study in Fiji reported a prevalence of 18% among school children (aged 5–15 years) and 14% among infants [9,10].

Pharmacy record review identified 1,733 children aged ≤14 years with a prescription for permethrin cream (5%) during 2011–2012; 1,139 of these children had a diagnosis of scabies in their medical record. Among the AS population of 19,425 children aged ≤14 years, we identified 613 children with scabies during 2011 and 526 during 2012. The annual average was 570 cases, or 29.3 cases/1,000 children. Estimated incidence was highest among children aged 0–4 years and declined with advancing age; children aged <1 year had the highest incidence (99.9/1,000 children), and children aged 14 years had the lowest incidence (7.3/1,000 children) (Table 1). Compared to children aged 10–14 years, children aged 0–4 years were 4.9 times more likely to have been diagnosed with scabies, and children aged 5–9 years were 2.2 times more likely to have been diagnosed with scabies (Table 2). Our study demonstrates that scabies and associated bacterial superinfections cause substantial morbidity among AS children. During 2011–2012, an average of 29.3/1,000 children and approximately 1 of 10 infants received a scabies diagnosis each year. Scabies incidence decreased with increasing age, which is consistent with previous studies [1,13]. This likely results from younger children being in close contact with multiple family members and often being held, which provides opportunities for exposure to infected family members. The predominance among males contrasts with previous studies; additional research is needed to understand the reasons for this difference [4]. Scabies does not appear to follow a seasonal pattern, which is expected in tropical regions where weather patterns are consistent throughout the year [4,9,23–25].   Source: http://doi.org/10.1371/journal.pone.0139336