Prevalence of Hymenolepis nana among primary school children in Burkina Faso

1 Laboratory of Animals Biology and Ecology (Burkina Faso), University of Ouagadougou, Burkina Faso. 2 National Center for Research in Science and Technology, Institute of Research in Health Sciences, Burkina Faso. 3 Ministry of Health/Directorate of Fight Against Disease, National Program to Fight Against Neglected Tropical Diseases (PNLMTN), Burkina Faso. 4 Helen Keller International, Regional Office for Africa, Ouagadougou, Burkina Faso. 5 Helen Keller International, Regional Office for Africa, Dakar, Senegal.


INTRODUCTION
Hymenolepis nana is the most prevalent parasite tapeworms (Magalhaes et al., 2013).It is a cosmopolitan parasite by its distribution and it is more prevalent in warm climates (Malheiros et al., 2014).It is endemic in Asia, Africa, Eastern and Southern Europe and Brazil (Huda Thaher, 2012;Malheiros et al., 2014).Infections due to H. nana are often asymptomatic when the level of infection is low (Mirdha and Samantray, 2002;Huda Thaher, 2012).But when the level of infection is heavy and chronic, these infections can cause diarrhoea, abdominal pain, headaches and dizziness (Mirdha and Samantray, 2002;Huda Thaher, 2012).Infections due to H. nana are associated with low absorption of vitamin B12 in the intestines (Mohammad and Hegazi, 2007).
Majority of the infections by H. nana is by self-infection through contaminated food or water with the eggs contained in faeces.The parasitic diagnosis is based on the detection of H. nana eggs in the faeces.There are many stool examination methods (Becker et al., 2011).The formalin-ether-concentration technique (FECT), Merthiolate-Iodure-Formol technique (MIF), Kato-Katz technique, direct analysis, Willis and Ritchie methods, etc., are the techniques for the diagnosis of H. nana infection.Among these methods, Kato-Katz technique is the most adapted for the research of helminths eggs (Kremer and Molet, 1975).Moreover, this technique can easily be carried out, and it is advisable for the survey (Montresor et al., 2004).H. nana is one of the causal agent of diarrhoea in Burkina Faso (Poda, 2007).It was detected several times in the hospitals (Ouermi et al., 2012;Cissé et al., 2011), and during the studies (Dianou et al., 2004;Poda et al., 2006;Zida et al., 2014;Sangaré et al., 2015).Therefore, the children of school age and adolescents in developing countries are the most exposed.H. nana is the most common tapeworm in the world and despite the consequences on the health of schoolchildren it has less attention (Magalhaes Soares et al., 2013).Unlike soil-transmitted helminths and schistosomiasis, there is no specific program against human hymenolepiasis.Burkina Faso started the fight against soil-transmitted helminths and schistosomiasis by treatment with praziquantel and albendazole.These medicines are not completely efficacious against H. nana with one dose (King, 2010).To fight against this parasite, it is necessary to do a mapping of the distribution of H. nana.This study proposes to initiate this approach in eleven of the thirteen regions that make up the Burkina Faso.This study aims to determine the prevalence of H. nana in primary schools in 13 regions of Burkina Faso.

Study sites
The study was conducted in 22 primary schools located in eleven regions (Figure 1).These sites are the sentinel sites for schistosomiasis and soil-transmitted helminthiasis of the national program of fight against neglected tropical diseases (PNLMTN).These sites were purposefully selected by PNLMTN to monitor the program impact on schistosomiasis.

Study population
The random sampling method was used to select participants in the study after explanation of the aims of the study with school children and their parents.The study population consisted of students from 22 selected schools in 22 villages.The age of the participants ranged from 7 to 11 years in both sexes.In each school, students were selected from the first year to the fourth year of the primary school.In each class, 32 students consisting of 16 girls and 16 boys were selected.Each child received a stool container to collect a stool sample.The stool samples were collected from 8 to 9 am.The samples were brought to laboratory in the cool box.The analysis of stool began 1 h after the collection at 10 am.

Parasitological analysis
The Kato-Katz method (Katz et al., 1972) was used for the detection of H. nana eggs in the feces.The stool samples were filtered through a filter and the filtered stool samples were applied to glass slides with spatula and Kato-Katz templates (41.7 mg).The sample on the slide was covered with a cellophane membrane previously impregnated in a malachite green solution for 24 h.Reading was taken using an optical microscope.The number of eggs counted per slide was multiplied by 24 for the intensity of infection in the number of eggs/gram of feces (epg).

Statistical analysis
Data were analyzed by SPSS 20.0 software.The prevalence and confidence intervals (95% CI) were determined.Chi quare test was used to compare the prevalence and p<0.05 was considered significant.Mann Whitney test was used to determine the distribution of H. nana eggs by sex.This test was used because there were only two variables.Kruskal-Wallis test was used to determine the distribution of the eggs of H. nana by region, age and the study sites.The arithmetic mean intensity of infections with standard errors (SE) were determined by taking into account all the participants.A geographical information system (GIS) software Quantum GIS-Valmiera (QGIS 2.2.0 -Valmiera) was used to plot the point prevalence of the infections for each primary school surveyed.

RESULTS
Three thousand five hundred and fourteen students participated in this study.The average age of participants was 9 ± 0.24 years.The overall prevalence of H. nana was 3.22% (95% CI: 2.69 -3.86%).The arithmetic mean intensity of the infection was 38.16 ± 8.96 epg.The highest intensity of the infection was found among students in the Sahel region (128 ± 31.34 epg), North (91.58 ± 78.86 epg) and Centre North (59.70 ± 33.50 epg).

Prevalence and intensity of infection according to the schools
According to the schools surveyed, the prevalence varied from 0 to 11.25% (Table 1 and Figure 1).There are four sites where H. nana was not found.The highest prevalence was found at Windou Primary School.The difference in prevalence among schools was statistically significant (p<0.001).The Kruskal-Wallis test showed that the distribution of H. nana eggs was not uniform (h<0.001).

Prevalence and intensity of infection according to the region and gender
The prevalence ranged from 0 to 9.38% by region.The highest prevalence was encountered in the Sahel region.The comparison of prevalence showed that the difference was significant between regions (p<0.001) but not by gender (p = 0.963).The Mann-Whitney test showed that the distribution of H. nana eggs was uniform by gender (h = 0.963).The Kruskal-Wallis test showed that the distribution of H. nana eggs was not uniform according to region (h<0.001).The distribution of prevalence and mean H. nana intensity by gender and by region is shown in Table 2.

Prevalence and intensity of infection according to age
The difference of prevalence by age was significant (p = 0.021) and the highest prevalence was among the school children of 7 years old.The Kruskal-Wallis test showed that the distribution of H. nana eggs was not uniform according to age (h = 0.02).The distribution of prevalence and mean intensity of H. nana infection is shown in Table 3.

DISCUSSION
Poverty is a factor which contributes significantly to the public health problems.In developing countries, there are diseases that are directly related to the lack of properties and hygienic practice.Among the diseases we can cite human hymenolepiasis.Indeed, the prevalence of H. nana can be considered an indicator of fecal contamination of environment and hygienic practice in a society (Magalhaes Soares et al., 2013).In our study, the prevalence of H. nana infection was 3.22%.But in previous studies conducted in Burkina Faso, the prevalence of H. nana was 3.99 to 12.2% (Dianou et al., 2004;Poda et al., 2006;Ouermi et al., 2012).These prevalence rates could be explained by many factors that facilitate transmission of H. nana in regions of developing countries such as Burkina Faso.Transmission of H. nana is facilitated by the consumption of food contaminated by feces containing H. nana eggs.Kpoda et al. (2015) found in Burkina Faso the eggs of H. nana in water used for irrigation.The absence of a fountain, the lack of hygiene, and the presence of people already infected with H. nana in the concession are factors that contribute to the maintenance of transmission (Mason, 1994;Al-Shammari et al., 2001;Huda Thaher, 2012;Magalhaes Soares et al., 2013;Malheiros et al., 2014).At home overcrowding in concessions is a factor that would increase the risk of contamination of H. nana eggs (Magalhaes Soares et al., 2013).Infection of H. nana is asymptomatic and according to Mirdha and Samantray (2002), the presence of an infected person in a crowded concession is a contributing factor to its expansion.Contamination may also be in primary schools.In Burkina Faso, there are small markets in primary schools where students buy food.The hygienic conditions are not met in these small businesses (sales places, lack of water for washing hands, absence of hygiene of the sellers).These businesses contribute to maintaining transmission of H. nana (Zongo et al., 2006).Indeed, a study in Iran showed that people who ate at the restaurants were the most exposed to intestinal parasites including H. nana (Sharif, 2015).In addition, children playing areas are not protected and often encounter animal and/or human feces.
In four sites, the prevalence was zero.This absence of H. nana may be due to the method used for this study.Because the Kato-Katz technique is not sensitive when the intensity of infection is low (Knopp et al., 2009;Becker et al., 2011).In our study, the prevalence obtained was low as compared to those obtained in Mexico (Martinez-Barbabosa et al., 2010), in Tajikistan (Matthys et al., 2011), in the East and Northeast of Ethiopia (Tadesse, 2005;Gelaw et al., 2013).The low prevalence may also be explained by the construction of latrines in schools and rural areas in Burkina Faso, the education of hygiene, the use of chemical fertilizers instead of stools in the fields and the countrywide deworming in schools by the various mass treatment programs.Studies have shown that praziquantel could be effective against infections caused by H. nana (Rim et al., 1978;Farid et al., 1984).But the praziquantel treatment alone may not be enough, niclosamide should be used together to eradicate H. nana in an infected person (King, 2010).When comparing the prevalence by age, it was noticed that the difference was significant (p = 0.021), but children of 7 and 8 years old are the most infected.This result could be explained by the fact that at this age, children are not abiding by the hygiene rules and generally they do not wash their hands after using the toilet (Huda Thaher, 2012).Similar studies have shown that children were the most infected (Martinez-Barbabosa et al., 2010;Magalhaes Soares et al., 2013;Malheiros et al., 2014).

Conclusion
This study presented the distribution of H. nana among primary schools in Burkina Faso.It helped to know the current situation of H. nana infection among students.But it should continue to include other socio-economic factors and extend the investigations to other community members.For now, awareness campaign should be made to school children.The fight against this parasite could be integrated into the control program against neglected tropical diseases.

Figure 1 .
Figure 1.Distribution of prevalence H. nana according to primary schools.

Table 1 .
Prevalence and intensity of H. nana infection according to the sites (primary schools).

Table 2 .
Prevalence and mean intensity of infection of H. nana according to region and gender.

Table 3 .
Prevalence and intensity of H. nana infection according to age.