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.