Intestinal parasitoses are diseases caused by parasites developing in the digestive tract [1]. According to the WHO, they are widespread virtually worldwide, with high prevalence in many tropical and subtropical regions. Amoebiasis, ascariasis, hookworm and trichocephalosis are among the ten most common infections worldwide. Although not associated with a high mortality rate, complications are not uncommon, and many cases require hospitalization. For the most part, intestinal parasitosis gives an idea of the level of individual and collective hygiene; the demographic explosion and promiscuity can be considered a major factor in the multiplication of cases in these environments [2]. The WHO estimates the number of people affected worldwide at over 2 billion, with an estimated 155,000 deaths per year [3].

However, these include intestinal helminthiasis, diseases caused by flat and/or round parasitic worms known as helminths, and intestinal protozoiasis, caused by single-celled parasitic organisms of the human intestinal tract known as protozoa. The magnitude of these intestinal parasitoses and their adverse impact on childhood survival justifies the need to implement strategies aimed at reducing the morbidity associated with these conditions [4].

In many countries, they represent a real public health problem, especially in developing countries where promiscuity, lack of drinking water and sanitary facilities are felt [1]. Although considered benign, they can lead to serious complications such as malnutrition, anemia, stunted growth in children [5].

Several studies on these intestinal parasitoses have been carried out in different regions of the world, including Africa, where climatic, hygiene and socioeconomic conditions, as well as inadequate sanitation, are conducive to parasite proliferation [6].

Considered a developing country, the Congo is no exception, and remains very concerned by these intestinal parasites.

In the Republic of the Congo, studies carried out by Nsimsa et al. in Brazzaville in 1991 revealed an overall prevalence of intestinal parasitosis of 16.59% [7]. However, data reported in 2011 on intestinal helminthiasis in the various arrondissements of the Brazzaville department showed an average prevalence of 5.49% throughout the urban perimeter [8]. Congo’s health pyramid means that CSIs (integrated health centers) are the first port of call for patients, especially children often suffering from known pathologies. As a result, decision trees (or algorithms) have been set up for the syndromic management of certain infections, notably parasitic infections in line with WHO recommendations [3]. These ISCs, which have only rudimentary laboratories, rarely perform parasitological analyses of stools. Therefore, in order to obtain recent data on an estimation of the prevalence of parasitic infections among children aged 1 to 5 years in the city of Brazzaville, four community health centers were selected for patient recruitment.

A total of 128 stool samples were analyzed in the laboratory. Each sample underwent macroscopic and microscopic examination. This study revealed an average prevalence of 14.06%, with 8.11% for CSI1, 20% for CSI2, 10% for CSI3, and 19.35% for CSI4. These results are lower than those obtained at the National Public Health Laboratory in 1991 (16.59%) in Brazzaville [7]. In fact, this prevalence could be explained by inadequate hygiene practices within households, as the study revealed a high prevalence among children who tested positive and who played outside the home—that is, in the yard or off the property (20%)—and most of whom do not receive, or rarely receive, deworming treatment (33.3%).

Our results are also lower than those obtained in Yaoundé, Cameroon [6] on “Intestinal Parasites in Children Aged Zero to Five Years”. In fact, of the 800 children they examined over a one-year period at two different study sites, 428 tested positive, representing a prevalence of 53.5%. Similarly, findings from Niamey, Niger [10], on “intestinal parasitic infections in children under 5 years of age,” showed a prevalence of 33%.

We also noted a higher number of positive cases (11) among children whose families use traditional latrines as their sanitation system compared to those whose families use modern toilets (7). The p-value (p = 0.242 > 0.05) indicates that there is no significant association between the occurrence of intestinal parasitic infections and the type of toilet used by households. It is important to note that the survey of the type of toilet used by each of the target households in our study was not exhaustive, and that during the survey, no home visits were made to the households of the children surveyed. We relied on the information provided by guardians during the survey. However, our results corroborate those obtained in Cameroon in the city of Yaoundé [6]. Their study found that: “Children whose families use a modern sanitation system are significantly less likely to be infested than others (χ² = 3.3; p = 0.0000),” although their p-value indicated a significant association between parasite carriage and the type of toilet used by households.

The variation in parasite prevalence rates observed in these studies can be attributed to regional differences, as countries in sub-Saharan Africa are the most affected due to unfavorable socioeconomic and hygienic conditions, as well as to sample size and the methodology used to collect the data.

In our study, the variation in prevalence by sex showed that 15.38% of our participants were male, compared with 12.70% who were female. Parasite carriage by sex was not statistically significant (p = 0.800 > 0.05). Our results corroborate the study conducted in Benin on “determining the proportion of intestinal protozoan infections among children aged 0 to 15 years admitted to the Order of Malta Regional Hospital in Djougou,” which found a prevalence of 53.85% among males compared to 46.15% among females [11].

The lack of a significant association between parasite carriage and patient gender may be explained by the fact that girls and boys are subject to the same hygiene conditions and face the same risk of infestation regardless of their gender. Parasite carriage was high among 5-year-olds (30.77%). No significant association was observed between age and parasite carriage (p-value = 0.221 > 0.05). These results corroborate those obtained in Cameroon, where children aged 2 to 3 years had a prevalence of 18%, those aged 3 to 4 years accounted for 52.33%, and those aged 5 years had a prevalence of 76.12% [6]. The peak incidence of parasitic infection therefore occurs between the ages of 3 and 5, when children start attending preschool and sometimes elementary school, and when close contact and group play particularly in soil—are thought to facilitate transmission. In their study, the p-value (p = 0.21 > 0.05) showed no association between age and parasite carriage, which corroborates our findings. However, our results contradict those obtained in Benin in 2013 on the “Prevalence of Intestinal Parasites Among Pediatric Patients at the Saint Jean de Dieu Regional Hospital in Tanguieta,” in which a high prevalence of parasitic infection was observed among children under 5 years of age, with a significant association between age and parasitic infection [12].

These findings suggest that children are prone to parasitic infections during their preschool years (between the ages of 3 and 5). This could be explained by the fact that at this age, children are in almost constant contact with the ground due to their recreational activities and also frequent environments (school, daycare, etc.) where close contact would facilitate the collective transmission of parasite eggs and/or cysts from one individual to another or from contaminated objects during group play.

The parasites isolated in our study were predominantly protozoa, accounting for 94% of the total, compared to 6% for helminths. Analysis of the samples ranked Giardiaintestinalis first with a prevalence of 61.1%, followed by Entamoebacoli (27.78%) and Ascaris lumbricoides (5.56%). Giardiaintestinalis is therefore the most dominant species in the studied population. These results are consistent with those obtained in Algeria, where the prevalence of protozoa was 96.65% and that of helminths 3.35% [13]. They also align with those obtained in Benin, with 87.5% protozoa and 12.5% helminths [12]. Similarly, those obtained in Cameroon, where the prevalence was three times higher than that of helminths, with a predominance of the species Giardiaintestinalis, which alone accounted for 52% of the identified positive cases [6].

In fact, an analysis of the literature shows that intestinal protozoa are predominant in most developing countries. These parasitic species are transmitted in cystic form primarily through poorly washed raw foods (fruits, vegetables, salads, etc.) and drinking water, which is most often drawn from waterways polluted by human waste and consumed without prior treatment [14].

This high prevalence of protozoa compared to helminths can be explained by the fact that, during the study, we observed that all children were treated for parasites exclusively with antihelminthic drugs such as albendazole, ABZ, Vermox, etc., which are primarily effective against helminths rather than protozoa. This is because, according to the literature review, protozoa require a specific treatment (metronidazole, Flagyl, etc.) different from that used for helminths, but this treatment is not often included in the standard regimen during individual or mass deworming campaigns.

In our study, of the 128 children examined, 17 had a single parasite (94.44%) and only one had multiple parasites (5.56%). These results are consistent with those obtained in Benin in 2021, where 92.31% of subjects had a single parasite and 7.69% had multiple parasites [11]. They are also similar to those obtained in Algeria, where 76.5% of subjects had a single parasite and 23.5% had multiple parasites [15].

We conducted our work at four (4) different sites spread across two zones (North and South). The study revealed a prevalence of 8.11% for CSI₁ (Sister Martin, Poto-poto), 20% for CSI₂ (Karin Johnson, Bacongo), 10% for CSI₃ (Fulbert Youlou, Madibou), and 19.35% for CSI₄ (Maman Mboualé, Talangaï). Parasitic species belonging to the protozoa group (Giardiaintestinalis and Entamoebacoli) were present at all study sites, particularly Giardiaintestinalis, which was identified at all four (4) sites with a high prevalence of 3.90% at the fourth site, followed by site 3 (2.3%). The Entamoebacoli species, on the other hand, was observed only at sites 1 and 2, with a high prevalence of 2.3% at the second site. Co-infection (Giardiaintestinalis + Entamoebacoli) was observed only at Site 2, with a prevalence of 0.8%. The helminth group was present only at Site 4 and was represented by a single species of geohelminth, Ascarislumbricoides, with a prevalence of 0.8%.

It should be noted that, as a commensal species, Entamoebacoli is considered an indicator of fecal contamination in subjects who test positive. In contrast, Ascarislumbricoides and Giardiaintestinalis are pathogenic; their presence raises suspicion of a parasitic infection.

These results could be explained by caregivers’ failure to properly implement personal and food hygiene measures, given that we are dealing with diseases linked to fecal contamination and that children in this age group (1 to 5 years old), who spend most of their time in prolonged contact with the ground, are potentially at risk. A strong emphasis on raising parents’ awareness of this issue would be a valuable asset in supporting chemoprevention against the occurrence of intestinal parasitic infections.

However, controlling the parasitic burden can only be achieved through environmental sanitation and hygiene, coupled with public health education. The variability in findings across different studies suggests that the risk factors for the transmission of intestinal parasitic infections are numerous and complex [16].

Since microscopy is a technique with varying degrees of sensitivity, it is important to note that a single stool sample examined under a microscope may or may not detect low level infections and, as a result, may underestimate the prevalence.

In conclusion, it is important to note that the estimated prevalence of intestinal parasitic infections among children aged 1 to 5 years is low but not negligible. This protozoan infection is primarily caused by giardiasis. Children become infected at a young age. The CSI Q24 Karin Johnson and Maman Mboualé sites each showed a higher prevalence compared to those at the CSI Fulbert Youlou and Sœur Martin sites.

During the period of this study, we encountered several constraints that made fieldwork rather complex, notably:

Linguistics concerning the national (Lingala) and vernacular (Lari) languages, which was a hindrance to good communication during the interview with the tutors of the study participants.Forgetfulness, negligence (broken or lost stool pot) on the part of the tutors, as well as their moving with the study participant outside Brazzaville immediately after the interview, making it difficult to collect samples in the record time allotted for each site.The study participant’s defecation habits. Indeed, stool sampling should take place early in the morning. However, we found that some children were quasi-constipated, while others only had bowel movements in the afternoon or evening. This also hindered our ability to collect samples in record time.Finally, in September, we encountered an equipment breakdown at the last site, extending the study’s planned completion time to four (4) months.