The infected subjects suffer from frequent physical and intellectual attacks due to anaemia, which results in a deficit of attention and inability to assimilate knowledge. By their spoliative action, the intestinal parasites interfere with the nutrition of the infected persons; they contribute to other factors and result in a veritable malnutrition and also increase morbidity and mortality (Crompton and Savioli, 1993). The purpose of the current study is to determine the status of intestinal parasites infection among students in a health professional training institution and to assess their level of perception of this health problem.

Study site

The institute chosen for this study is here named XX for ethical reasons. It is a model in the training of paramedics in Chad. It has two sections (French and Arabic). The French section has two cycles; its lower cycle teaches the following sectors: state-certified nurse (SCN), midwife, technical health assistant [THA]. Its higher cycle consists of the sectors of biomedical analysis and pharmacy (BM). The Arabic section is a replica of the francophone. This institute is equipped with a laboratory of medical analysis, nursing demonstration rooms, gyneco-obstetrics and a library.

Study population and sampling

Our sample consisted of 107 students who took and enrolled at institute XX for the 2017-2018 academic years. The cluster sampling technique (Combes,  1989;  Fleiss,  1981)  allowed  us  to select them within the establishment. The authorization to conduct this survey was solicited and obtained from the administration after studying our project, which was attached to the informed consent form. The day before the investigation, a visit was made in the classes in order to sensitize the students on the nature, importance, the necessity of this work and to get their membership in large numbers. A questionnaire developed on a survey sheet was designed to identify problems on general hygiene and nutrition of each participant. After mentioning his or her name on the card, each subject received an identification number on a labelled sterilized stool vial containing 2 ml of formalin diluted to 10% in order to fill it with a stool. The samples were quickly sent to the institute’s laboratory for analysis.

Analysis of stool

Each sample of stool was examined macroscopically and direct microscopic examination was done, followed by the formalin-ether concentration technique (Golvan and Ambroise, 1984; Marti and Escher, 1990). A subject was considered parasitized if an adult worm, at least one cyst or one form of vegetative protozoa, an egg ore one helminth larvae was found.

Direct examination

Macroscopic examination

Macroscopic examination consists of noting the consistency, the colour, the appearance of the faeces, and the eventual presence of segments of cestodes, larvae, and adult worms of nematodes (Gentillini , 1993).

Microscopic examination

For the direct examination of stools in the fresh state, a drop of physiological water was put on a slide. One or two pinches of stool were stirred and a drop of 10% Lugol was added to the mixture. Then a cover slip was placed on it. The preparation was allowed on the bench for 5 to 10 mn at room temperature in the laboratory. This was proceeded by examination under the microscope. First using the objective of X10, then the objective of X40 to better observe the parasitic contrast (Gentillini, 1993; Utzinger et al., 2009).

Methods of formalin-ether concentration

For the methods of formalin-ether concentration, we used the Procedure of the following authors: Golvan and Ambroise (1984),  Gentillini (1993) and Utzinger et al. (2009).

Data analysis

Data  entry  and  processing was done using the following software:  CSPro  version  7 and SPSS version 25Chi² ()test, sometimes with the correction of Fischer’s exact test, which allowed us to compare the different proportions where possible (Combes, 1989; Fleiss,1981).

During our research, most of the stools were pasty (50.46%) or soft (33.64%); the liquid and blood stained were the lowest (Table 1).This finding was also reported by Hamit et al. (2008). This is due to the nutrition of Chadians which is mainly cereals (Tidjani et al., 2006). A total of 64.5% of students harboured at least one species of intestinal parasite (Table 2). Our results are closed to other studies done in regions of Africa. In Tunisia for example, Thiers et al. (1976) found a global index of  infection of 53.4% in a school establishment. However, differences between the two levels of infections  may be attributed to the number of samples used in both researches, the methodology used in the laboratory, the climatic conditions and the socio-economic status. Equally, the educative status of the population being studied and their way of life may play an important role. The prevalence found in our study indicates the intensified promiscuity and a lack of collective and individual hygiene in the city of N’Djamena. Above  all the participants had very little education on hygiene but the environmental conditions are favourable to the development of cysts of protozoa and eggs of helminths. The prevalence found in this study could be higher if specific research procedures were used for certain species of parasites, such as nematodes: S. stercoralis and E. vermicularis (OMS, 1983; Tchuem et al., 2012). The local conditions of our laboratory and the logistic constrain did not permit us to employ other technics; however, the methods utilized have the advantages of being simple, rapid, less costly and perfectly adapted for economically weak country (Tchuem et al., 2012).

In the course of this survey, monoparasitism for each of the listed species concerned 53.27% of students and polyparasitism and precisely biparasitism 11 .21%. The difference is not significant (P>0.05 and =43.31) (Table 3). Between the six possible bispecific associations, only that of T. solium /A. lumbricoides was not seen. These double appearances are rare (3% ba%  5%) or very rare (ba% 2%).   Then the presence of parasitic associations indicates a low level of hygiene (faecal peril) and unfavourable living conditions. The predominance of monospecific infection by E. histolytica, A. lumbricoides and G. lamblia on one hand and on the other  parts,  their  association (E.  histolytica / A. lumbricoides and E. histolytica / G. lamblia) can be explained by their infection mode that of the oral part way (NKengazong et al., 2010; Youssef et al., 2009).

The results showed  five parasitic taxa were identified: three species of helminths which were two nematodes A. lumbricoides (13.08%) and S. stercoralis (0.93%) and one cestode T. solium (1.87%); and two species of protozoa E. histolytica (46.73%) and G. lamblia (13.08%) (Table 4). There was no significant difference (P> 0.05) noted on the levels of infestation by the different species of parasites according to gender (Table 4).

Our study confirmed that amoebiasis, a neglected tropical disease remains a serious public health problem in countries that are south of the Sahara because it is responsible for almost 100.000 deaths yearly (Bourée, 2010;  Bastie, 2013; Moustapha, 2016). This finding dose explains not only the important genetic polymorphisms of amoeba (Wendpagnande, 2015) but equally the solid links in the mode of faecal oral transmission and the existence of many healthy asymptomatic carriers. It can be noted that flooding during the rainy season in certain quarters in the city of N’Djamena is favourable to the dissemination of cysts (Hamit et al., 2008); on the other hand, the anarchical dumping of garbage frequently favours  contamination  of drilling  water  and  well  water. The hot climates also permits the rapid and abundant development of flies, the mechanical vectors for the dissemination of cysts.

In Chad, water is generally stocked in canaries, because these containers keep the water cool. This system of storage does not reduce the dissemination of parasites due to poor maintenance and bad utilization. In this study 69.38% of the users of water from canaries were infected. In our study, 93 students declared that they always washed their hands with soap before eating but from the 93 students, 58 or 62.36% of them were parasitized (Table 5). This result can be attributed to the lack of proper technics in washing hands with soap. In fact the importance of the technic of washing  hands  with water has been signalled by Tidjani et al. (2013, 2016). Plastics kettles are systematically used by the Chadian population for their toilets in latrines. This study shows that these materials should be strictly hygienic (73.75%, Table 5). Table 5 shows that toilet papers are poorly used by the students. Generally, in Chad, eating of meals is done collectively and also washing of hands by every individual is necessary or primordial (Hamit et al., 2008).

From the 107 students examined, 69 (64.5%) harboured one or more species of intestinal parasites. Five species of parasites were identified: E. histolytica, G. lamblia, A. lumbricoides, T. solium and S. stercoralis . E. histolytica is the dominant specie among the students. These data are not encouraging for future Chadian health officers. There is therefore, an urgent need to enforce individual and collective hygiene.

The authors have not declared any conflict of interests.