Ascariasis—the most prominent infection of thesoil-transmitted helminths (STH)— is caused by Ascaris lumbricoides.
Childrenare most often affected by ascariasis due to poor hygiene and frequent exposureto soil and unsanitary conditions. An infection of ascariasis can lead to short-termand permanent growth deficits as well as minor and acute illness. The severityof the condition often relates to the worm-load in the child.
Intestinalascariasis is the most common acute illness associated with A. lumbricoides,and it often involves a partial or full blockage of the intestines. Typicaltreatments of intestinal ascariasis start out conservatively through the use ofassistive care, and in severe cases, surgery is performed to remove theintestine containing the obstruction. The primary means to address intestinalascariasis is through prevention. Prevention is done through mass drugadministration (MDA) and addressing water treatment, sanitation, and hygiene(WASH) behaviors in communities burdened by ascariasis.
Future interventionsshould be focused at community and school levels with a focus on targetingyoung children with WASH and sex-specific interventions to decrease the ratesof infection and reinfection of ascariasis. To address children who may alreadybe infected with ascariasis, MDA programs should be used to decrease the prevalenceof ascariasis. MDA and WASH should be coupled together in communities and inschools to have the most significant impact on decreasing prevalence and intensityof ascariasis. BackgroundAscariasis is one of the earliest known helminthinfections known by humans, and the infection is due to Ascaris lumbricoides.Today, it is the most prevalent soil-transmitted helminth infection (deSilva etal.
1997).The numbers:• Approximately 1.3 billion people have ascariasisaround the world.• 51 million children under 15 years old riskgrowth deficits and reduced fitness levels.
• Of the 51 million children, 1.5 million willmost likely have permanent deficits in growth.• Approximately 11.5 million children have a highrisk of acute illnesses and chronic effects due to ascariasis. • Around 200,000 children have infections thatresult in a severe complication like an intestinal obstruction • Of the deaths due to complications ofascariasis, more than 90% are children (deSilva et al. 1997).
The lifecycle of A. lumbricoides and process ofhuman infection is demonstrated in Figure 1: • The female worm produces eggs in the intestinesthat are passed into the environment through feces• Ingestion of egg occurs from environment• The larvae migrate and end in the intestinewhere growth and maturation occur (Khuroo 1996) PopulationAffected by AscariasisAscaris lumbricoides infection is often prevalent in communities where: • Nightsoil—humanfeces—is used to fertilize food (Khuroo 1996).• Lowsocioeconomic status is prevalent.
• Thecommunity is in a rural location (Wani et al. 2010). Of all agegroups, infection of ascariasis impacts children the most (Khuroo 1996).Children aged:• 2 to 3experience a sharp increase in prevalence of ascariasis. • 4 to 14experience the maximum prevalence of ascariasis (Louw 1966).• 15 andinto adulthood experience a decrease in prevalence (Khuroo 1996).
Infection inchildren often occurs because of poor hygiene and frequent exposure to soilthrough: • Geophagy:eating dirt• Dirtytoys containing soil or feces• Fingers(Khuroo 1996)• Walkingbarefoot (Freeman et al. 2013) MedicalComplications The morbidity of ascariasis is categorized in 4 ways:• Non-permanent growth and fitness deficit • Permanently altered/hindered growth• Brief and mild illness• Acutecases (deSilva et al. 1997)Often times, the worm burden can be associated with thelevels of morbidity, and those with higher worm burdens are at risk for moresevere complications such as intestinal ascariasis (deSilva et al. 1997). The determination between a mild illness and an acutecase is the severity of the symptoms. Children with an acute case tend to showthe following symptoms:• Severe sickness• Dehydration• Elevated fever• Severe abdominal symptoms (Louw 1966)The abdominal symptoms of intestinal ascariasis are:• Abdominal pain• Abdominal distention• Nausea• Diarrhea• Vomiting worms (Wani et al.
2010)• Worms in feces (Louw 1966) Approximately 70% of acute cases are due to intestinalascariasis and intestinal obstruction, and these high numbers of intestinal ascariasisare demonstrated in Figure 2 (deSilva et al. 1997). In children, intestinalAscariasis is a common complication due to heavy a heavy worm-burden causing anobstruction—partial or full blockage— in the intestines. (Khuroo 1996)Symptoms tend to present due to the mass of wormscreating an inflammatory response which leads to full or partial intestinalobstruction (Louw 1966). TreatmentOptionsTreatment of an intestinal ascariasis typically isconservative and focuses on: • Providing intravenous fluids and electrolytes • Administering anti-helminthics and antibiotics• Supportive care such as nasogastricdecompression or enemas (Wani et al.
2010)Surgery is performed in cases when there was• Poor response to conservative treatment • Bleeding• Severity of symptoms much greater than the levelof obstruction (Wani et al. 2010)• Positive rebound sign on the abdomen (Louw 1966)• Positive imaging results of significant massleading to peritonitis (Wani et al. 2010)Risks of not operating in severe cases• Perforation of the bowel• Intestine dying and gangrene occurring (Louw1966) PreventionStrategies OverviewThere are 2 common prevention strategies shown to beeffective in decreasing the prevalence of ascariasis:• Mass drug administration • Water treatment, sanitation, and hygieneimprovements The most effective prevention strategies target both WASHand MDA (Freeman et al. 2013).
Mass Drug Administration (MDA)MDA has proven to be effective in decreasing theprevalence of ascariasis as seen in Table 1. Both levamisole and albendazole have been proven to beeffective in reducing the prevalence of ascariasis in children. In comparisonto a placebo, albendazole drastically decreased the prevalence of ascariasis asseen in Figure 3 (Kirwan et al. 2009). Mass Drug Administration ContinuedThe frequency in which a child receives anti-helminthicsis a factor in the reinfection rate. Those with more doses of ananti-helminthic per year, most likely lead to lower reinfection rates.
As seenin Figure 4, administration of levamisole drastically reduces the number ofworms passed in the feces, and it keeps the morbidities of ascariasis low.However, with 6 month dosage intervals, the prevalence of worms in the fecesincreases to a prevalence near 70% before anti-helminths are given again(Hlaing et al. 1990). In comparison, the dosage of albendazole every 4 monthsleads to a continued decrease the prevalence of ascariasis (Kirwan et al.2009).
Water Treatment, Sanitation, and Hygiene (WASH)As seen in Table 2, WASH has been shown to have apositive impact in regards to decreasing the prevalence of ascariasis; however,there are difficulties with improved water sources and differences amonggenders. The study by Freeman et al. shows the positive impact ofWASH in reducing the prevalence of ascariasis in school children (2013).However, as noted by Garn et al.
an increase in hygiene behaviors onlysignificantly reduces the rate of ascariasis in cases where there is access toan improved water source, and 47% of the schools did not have an improved watersource (Garn et al. 2016).A challenge identified in Freeman et al.
(2013) is thevariation in sex-specific behaviors and responses to WASH interventions. Femalechildren experience a greater impact. May have to do with:• Reduced exposure to fecal matter• Greater use of latrines (Freeman et al.
2013) Conclusions andRecommendationsConclusionsChildren are atgreater risk of ascariasis infections due to their nature of decreased hygienebehaviors and greater contact with soil and feces (Khuroo 1996). Community andschool-based MDA and WASH interventions have proven to be effective indecreasing the prevalence of ascariasis; however, there are issues with WASHinterventions being more effective for girls than boys (Freeman et al. 2013).Additionally, there are problems with a lack of improved water sources whichcauses increased hygiene behaviors to be ineffective when trying to decrease theprevalence of ascariasis (Garn et al. 2016).
RecommendationsFutureinterventions should continue to focus on:• ImplementingMDA programs targeting children at school starting from a preschool age (Kirwanet al. 2009)• Improvingsanitation conditions in schools and in communities• Increasinghygiene behaviors of children Futureinterventions should work on: • Addressingthe gap of WASH intervention effectiveness with hygiene behaviors that aretargeted towards male school children• Obtainingimproved water sources in more schools and communities• AdministeringMDA more frequentlyBy tailoring theWASH interventions to address the difference in behaviors between sexes, theyshould have a greater impact on the prevalence of ascariasis in boys.Additionally, improved water sources will allow for future hygiene andsanitation to be more effective.
Finally, more frequent MDA will decreasereinfection amounts.