Effect of Mass Stool Examination and Mass Treatment For Decreasing Intestinal Helminth and Protozoan Infection Rates in Bolivian Children: A Cross-Sectional Study

<div><p>Bolivia is one of the countries with a high intestinal helminth and protozoan infection rate. Despite the high prevalence of the parasitic infection, nationwide preventive measures for Bolivian children have not yet been implemented. We evaluated the effect of mass stool examination and treatment as a strategy for decreasing the infection rate. This study was conducted between 2013 and 2015 in children aged 2–18 years. A total of 2,033 stool samples (575 in 2013, 815 in 2014 and 642 in 2015) were collected and examined using the formalin-ether medical sedimentation method. As an anthelminthic medicine, nitazoxanide was given to all infected children within 2 months post-examination, each year. The effect of mass stool examination and treatment was evaluated based on the changes in the overall or individual parasitic infection rates during the study period. The overall parasitic infection rate decreased significantly from 65.2% in 2013 to 43.0% in 2015; a 22.2 percentage point decrease (P<0.001). Protozoan infection accounted for a large portion of the parasitic infections, in the following rates: 62.4% in 2013, 49.3% in 2014, and 41.0% in 2015. The rate of the most common helminth infection, <i>Hymenolepis nana</i>, decreased significantly from 9.0% in 2013 to 6.4% in 2014 to 3.4% in 2015 (P<0.001). Prevalence of the most common pathogenic protozoan infection, <i>Entamoeba histolytica</i>, decreased significantly from 19.0% in 2013 to 3.0% in 2015 (P<0.001). Conversely, the rate of <i>Giardia intestinalis</i> increased significantly from 16.5% in 2013 to 21.2% in 2015 (P<0.01). Mass stool examination and treatment for intestinal helminth and protozoan infections was effective for decreasing the overall parasitic infection rate in the study population, excluding <i>Giardia intestinalis</i>. Further studies on the long-term effect of mass stool examination and treatment for decreasing all intestinal parasitic infection rates in Bolivian children are needed.</p></div

Changes in intestinal parasitic infection rates of Bolivian children in the study in 2013, 2014, and 2015, by parasite type and year.

<p>Changes in intestinal parasitic infection rates of Bolivian children in the study in 2013, 2014, and 2015, by parasite type and year.</p

Changes in helminth and protozoan infection rates of Bolivian children in the study in 2013, 2014, and 2015, by parasite species and year.

<p>Changes in helminth and protozoan infection rates of Bolivian children in the study in 2013, 2014, and 2015, by parasite species and year.</p

Changes in the number of helminth or protozoa species found in Bolivian children between 2013 and 2015.

<p>Changes in the number of helminth or protozoa species found in Bolivian children between 2013 and 2015.</p

MM3-COPRO ELISA and intensity of <i>Fasciola hepatica</i> infection in the low burden group of Huacullani.

<p>Data points represent the mean absorbance at 492 nm from egg positive children from Huacullani. epg represents the egg count per gram of feces. The dotted line represents the cut-off value 0.097 units of OD at 492 nm.</p

MM3-COPRO ELISA in feces from children (n = 436) from Huacullani (Northern Bolivian Altiplano).

<p>Data points represent the mean absorbance at 492 nm obtained from three replicates of each sample tested. The dotted line represents the cut-off value 0.097 units of OD at 492 nm.</p

Theoretical PPVs and NPV values vs fascioliasis prevalence.

<p>Curves show the expected PPVs (continuous line) and NPV (dotted line) values in low (below 1%), medium (between 1% and 10%) or high (above 10%) prevalence scenarios (expressed in vertical lines) in Huacullani (A) and Cajamarca (B).</p

Performance characteristics of MM3-COPRO ELISA by study site.

<p>Positive cases (%) of MM3-COPRO ELISA and egg detection techniques of <i>Fasciola hepatica</i> infection.</p><p>N^a = total number of positive children with <i>Fasciola</i> infection by Kato–Katz.</p><p>N^b = number of children analyzed.</p><p>AM = arithmetic mean; GM = geometric mean.</p><p>Identification of true positive and true negative cases was carried out by using two criteria:</p><p>i) finding of <i>F. hepatica</i> eggs in feces (*); ii) egg finding plus COPRO ELISA test results (**).</p

MM3-COPRO ELISA in feces from children (n = 362) from Cajamarca valley (Peru).

<p>Data points represent the mean absorbance at 492 nm obtained from three replicates of each sample tested. The dotted line represents the cut-off value 0.097 units of OD at 492 nm.</p