Intestinal parasitosis is a condition caused by the presence of helminths and/or parasitic protozoa in the intestine. According to the WHO, there are more than 1.5 billion people, 1.5 billion infected people or 24% of the world’s population. These infections are responsible for 155,000 deaths each year. In 2020, chemoprevention for geo-helminthiasis was needed in 87 countries [1] [2] .

Many species of parasites belonging to different classes can colonize the human digestive tract and school-age children constitute a very exposed population. Several studies have shown the high prevalence of intestinal parasitosis in this category of the population [1] - [3] . Previous studies carried out in Senegal have shown variable prevalences of intestinal parasitosis of up to 35% in rural areas and 20% in urban areas [3] - [5] . This variation may be due to various factors (environmental, socio-economic, lifestyle, etc.). The results of baseline surveys carried out in 2013 at national level revealed a prevalence of intestinal parasitic infections of 21.9%. Ascaris lombricoides was the main cause of parasitic infection, accounting for 46.7% of cases observed [6] .

Geohelminths are transmitted by eggs excreted in the faeces of infested people. Adult worms live in the intestines, where they lay thousands of eggs every day. In places where sanitation facilities are inadequate, these eggs contaminate the soil and are passed on to humans through dirty hands, contaminated water, etc [1] .

The pathogenicity of these parasites is variable, ranging from simple asymptomatic carriage to extremely serious or even fatal symptomatic pictures. Although the symptoms often go unnoticed, these parasites aggravate the problem of malnutrition and anemia, which stunt growth and make the child vulnerable to other diseases and influence school performance [7] [8] .

To combat this problem, the World Health Organization has recommended since 2001 to deworm children under 5 years of age. Thus, Senegal, through the Ministry of Health and Social Action, has been implementing deworming campaigns with mebendazole (later replaced by albendazole) since 2006 [1] [4] . In Senegal, satisfactory therapeutic coverage of mass drug distribution was noted between 2015 and 2019, ranging from 87% to 100%. During these five years (2015-2019), the geographical coverage of mass drug distribution was 100%, with the exception of 2019 when it was 50%, probably due to the Covid-19 pandemic. This strategy for preschool and school-age children has significantly reduced the frequency of intestinal parasitosis in this target group, with a reduction in morbidity of more than 81% 4 - 6 [6] .

This one-year retrospective study (2018-2019) aims to re-evaluate the epidemiology of intestinal parasitosis in paediatric hospitals after several years of mass treatment and analyze their socio-demographic and biological characteristics (age, sex, gross and microscopic examination of stool).

Intestinal parasites are very common and represent a public health problem on a global scale. Their prevalence is very high in Third World countries, where environmental and social characteristics favour their development and are factors in the perpetuation of these infections. Senegal’s objective is to eliminate geohelminthiasis by 2030. The strategies implemented to achieve this goal are: availability of Albendazole or Mebendazole, organisation of mass drug distribution campaigns (therapeutic coverage ≥ 75% of children aged 5 to 14 in all endemic districts), case management, promotion of hygiene and sanitation measures, awareness-raising and organisation of impact surveys.

As part of the WHO initiative to combat neglected tropical diseases, Senegal’s Ministry of Health and Social Action launched a mass deworming programme for children several years ago to combat intestinal parasitosis in this vulnerable segment of the population.

Our study aims to provide the most recent data on the situation of intestinal parasitosis in children in Senegal after several years of mass treatment.

A prevalence of 12.34% was found, and different types of parasites were isolated during our work, with a predominance of protozoa (76.14%) compared to helminths 23.86%. Similar results were observed by Lélo et al. in Dakar suburbs in 2019. Sylla et al., in 2013, found a higher prevalence of 35% in rural areas [3] [9] . In various studies carried out in Senegal, the same epidemiological profile as ours has been found, particularly in the predominance of protozoa. Lélo et al. found that 44.73% of the parasites found in his study were protozoa and for Sylla et al. 93.4%. This is probably due to the improved sensitivity of mebendazole to helminths, which is used in mass treatment campaigns.

In the subregion, other authors had also reported high prevalences of intestinal parasitosis. This is the case of Cisse et al. in Burkina Faso, who reported a prevalence of 54.7% in a retrospective study from 1997 to 2007 [10] .

A study carried out in Côte d’Ivoire by Yapi et al. in 2005, showed a prevalence of 68.2% of intestinal parasitosis with a predominance of protozoa over helminths [11] . A study conducted by Buzigi et al. in Uganda, in 2014, showed a prevalence of intestinal parasitosis of 54.4%, Giardia intestinalis was the most common parasite followed by Entamoeba histolytica while helminths were poorly represented [12] .

Intestinal parasitism in children over 5 years of age was higher (53.98%) compared to children under 5 years of age (46.02%). Contradictory results have been reported in Senegal by Tine et al. in 2013, indicating a predominance of protozoa in children under 5 years of age [13] .

Male children were the most affected (57.95%). Lélo et al. in Dakar and Chaudhry Zh et al. in Pakistan reported similar results (22.7% and 31.6%, respectively) [8] [14] . However, the study conducted by Sylla et al. in a rural area in the commune of Keur Socé in Senegal showed a higher prevalence in female subjects than in males, although without any significant difference [3] .

The consistency, presence of red blood cells, leukocytes, yeasts, and clinical indication do not seem to be decisive for the presence of parasites in the stool (p-value higher than 0.05).

Regarding the frequency of parasites according to stool consistency, our results confirm the data from Aplogan A et al. which show that no parasite seems to be directly and exclusively responsible for the appearance of stool in children. [15] .

The results of our study show once again the endemic nature of intestinal parasitosis in Senegal, with a non-negligible hospital prevalence at the Albert Royer Children’s Hospital dominated by protozoa in all age categories. The lower rate of infestation among children under 5 years of age is probably the result of the action of the Ministry of Health and Social Action. Hence, there is a need to continue the mass administration of Albendazole coupled with vitamin A in children aged 6 months to 59 months to fight against fecal perils and to promote health education for behavioral change.