Intestinal parasitic infections are highly endemic among school-aged children in resource-limited settings. To lower their impact, preventive measures should be implemented that are sustainable with available resources. The aim of this study was to assess the impact of handwashing with soap and nail clipping on the prevention of intestinal parasite reinfections.
Methods and Findings
In this trial, 367 parasite-negative school-aged children (aged 6–15 y) were randomly assigned to receive both, one or the other, or neither of the interventions in a 2 × 2 factorial design. Assignment sequence was concealed. After 6 mo of follow-up, stool samples were examined using direct, concentration, and Kato-Katz methods. Hemoglobin levels were determined using a HemoCue spectrometer. The primary study outcomes were prevalence of intestinal parasite reinfection and infection intensity. The secondary outcome was anemia prevalence. Analysis was by intention to treat. Main effects were adjusted for sex, age, drinking water source, latrine use, pre-treatment parasites, handwashing with soap and nail clipping at baseline, and the other factor in the additive model. Fourteen percent (95% CI: 9% to 19%) of the children in the handwashing with soap intervention group were reinfected versus 29% (95% CI: 22% to 36%) in the groups with no handwashing with soap (adjusted odds ratio [AOR] 0.32, 95% CI: 0.17 to 0.62). Similarly, 17% (95% CI: 12% to 22%) of the children in the nail clipping intervention group were reinfected versus 26% (95% CI: 20% to 32%) in the groups with no nail clipping (AOR 0.51, 95% CI: 0.27 to 0.95). Likewise, following the intervention, 13% (95% CI: 8% to 18%) of the children in the handwashing group were anemic versus 23% (95% CI: 17% to 29%) in the groups with no handwashing with soap (AOR 0.39, 95% CI: 0.20 to 0.78). The prevalence of anemia did not differ significantly between children in the nail clipping group and those in the groups with no nail clipping (AOR 0.53, 95% CI: 0.27 to 1.04). The intensive follow-up and monitoring during this study made it such that the assessment of the observed intervention benefits was under rather ideal circumstances, and hence the study could possibly overestimate the effects when compared to usual conditions.
Handwashing with soap at key times and weekly nail clipping significantly decreased intestinal parasite reinfection rates. Furthermore, the handwashing intervention significantly reduced anemia prevalence in children. The next essential step should be implementing pragmatic studies and developing more effective approaches to promote and implement handwashing with soap and nail clipping at larger scales.
In a factorial cluster randomized controlled trial, Mahmud Abdulkader Mahmud and colleagues examine the efficacy of handwashing with soap and nail clipping on intestinal parasitic infections in school-aged children.
Intestinal parasitic infections are common human infections, particularly in resource-limited countries, where personal hygiene and access to clean water and sanitation (disposal of human feces and urine) is often poor. Worldwide, more than a billion people are infected with soil-transmitted helminths—roundworms, tapeworms, and other parasitic worms that live in the human intestine (gut). And millions of people are infected with protozoan (single-celled) intestinal parasites that cause diseases such as amebiasis and giardiasis. Both helminths and protozoan parasites are mainly spread by the fecal-oral route. Infected individuals excrete helminth eggs and protozoan parasites in their feces, and in regions where people regularly defecate in the open, the soil and water supplies become contaminated with parasites. People then ingest the parasites by eating raw, unwashed vegetables, by not washing their hands after handling contaminated soil, or by drinking contaminated water. Mild infections with helminths rarely have symptoms, but severe infections can cause abdominal pain, diarrhea, and malnutrition. Protozoan parasites also cause diarrhea. Importantly, among children, who are particularly susceptible to parasitic infections, intestinal parasite infections may slow growth, affect school performance, and cause anemia.
Why Was This Study Done?
Intestinal worm and protozoan infections can be treated with anthelmintic drugs and antibiotics, respectively. However, reinfection is often rapid, and, particularly in resource-limited countries, additional preventative measures are needed that do not rely on drugs (parasites can become drug-resistant) and that are sustainable with available resources. Given that intestinal parasitic infections usually spread through the fecal-oral route, the promotion of handwashing with soap and regular fingernail clipping might be one way to reduce intestinal parasite infection rates in low-income settings. Handwashing prevents other types of infection, and both unwashed hands and dirty, untrimmed nails are associated with high rates of parasite infection. Here, the researchers investigate whether handwashing with soap and nail clipping reduce intestinal reinfection rates by undertaking a factorial cluster randomized controlled trial (a study that compares outcomes in groups of people chosen at random to receive different combinations of two or more interventions) among school-aged children in northern Ethiopia.
What Did the Researchers Do and Find?
The researchers assigned 367 parasite-negative school-aged children to receive a handwashing intervention, a nail clipping intervention, both interventions, or neither intervention for six months. For the handwashing intervention, fieldworkers visited each intervention household weekly, provided soap, encouraged all the household members to wash their hands with water and soap at key times, such as before meals and after defecation, and checked on the household’s use of soap. For the nail clipping intervention, the fieldworkers clipped the nails of children in the intervention households every week. After six months, parasite reinfection (primary outcome) and anemia (secondary outcome) in the participants were assessed by examining stool samples for parasites and by measuring hemoglobin levels, respectively. After adjustment for factors likely to affect reinfection such as latrine use and drinking water source, 14% of the children in the handwashing with soap groups (handwashing alone and handwashing plus nail clipping) were reinfected with parasites compared to 29% of the children in the no handwashing groups (nail clipping only or neither intervention). Similarly, 17% of the children in the nail clipping groups were reinfected compared to 26% in the no nail clipping groups. Finally, handwashing (but not nail clipping) significantly reduced the rate of anemia among the children.
What Do These Findings Mean?
These findings show that handwashing with soap at key times decreased intestinal parasite reinfection rates by 68% and that weekly nail clipping reduced reinfection rates by 49% among school-aged Ethiopian children. Thus, these findings support the promotion of proper handwashing and weekly nail clipping as a public health measure to reduce parasite reinfection rates in resource-limited regions. However, although both interventions were “efficacious” under trial conditions that included intensive monitoring and follow-up, handwashing and nail clipping may not be “effective” interventions. That is, they may not work as well under real-life conditions. Moreover, because long-established personal hygiene and sanitation practices may be hard to change, large-scale implementation of these interventions might be expensive. The researchers call, therefore, for pragmatic studies to be undertaken to investigate the performance of these interventions under real-life conditions and for the development of effective approaches for widespread promotion of handwashing with soap and nail clipping.
This list of resources contains links that can be accessed when viewing the PDF on a device or via the online version of the article at http://dx.doi.org/10.1371/journal.pmed.1001837.
The US Centers for Disease Control and Prevention provides basic information about protozoan parasites and helminths; its Alphabetical Index of Parasitic Diseases provides more information about roundworms, tapeworms, giardiasis, amebiasis, and other intestinal parasites/parasitic infections; it also provides information about handwashing and about handwashing as a family activityThe World Health Organization provides detailed information about intestinal worms, including a description of its current control strategyPARA-SITE is a multimedia resource provided by the Australian Society of Parasitology that provides detailed information about the biology of intestinal and other parasitesKidsHealth, a site provided by the US-based non-profit Nemours Foundation, provides information for parents, kids, and teenagers about several intestinal parasites and about the importance of handwashing for parents, kids, and teenagers (in English and Spanish)