Prevalence of Blastocystis sp. among cooks in the region of Fez-Meknes (Morocco)

Parasitic infestations, especially those caused by protozoa, have long been a public health problem. According to the World Health Organization (WHO), nearly a third of people in developed countries are affected by parasitic intestinal infections, while the rate is five times higher among people in developing countries (Gizaw et al., 2014; Tulu et al., 2014). Blastocystis sp. is one of these protozoa, the most identified in symptomatic and asymptomatic patients during parasitological stool examinations (PES) (Thathaisong et al., 2003; Wong et al., 2008). It is a unicellular anaerobic eukaryotic parasite, frequently reported in humans and animals worldwide (Wongthamarin et al., 2018). Its prevalence varies from 55 to 100 % in developing countries and from 7 to 50 % in developed countries (Lhotská et al., 2020; Wakid et al., 2022)

Currently, 28 subtypes (ST) have been described based on sequence comparison of the 18S rRNA gene denoted ST1 to ST28, while only 24 subtypes meet the currently recommended criteria for subtype identifications, their numbers are: ST1–ST17, ST21, ST23–ST28. Subtypes between them (for example ST18–20, ST22) are chimeras (Stensvold & Clark, 2020). The contribution of this microorganism to pathogenicity is increasingly proven, although long considered non-pathogenic, recent studies have suggested a strong correlation between infection with Blastocystis sp. and digestive disorders (Yakoob et al., 2010; Hayashi et al., 2006). In particular, food handlers constitute a population at high risk of contamination and spread of this parasite (Idowu & Rowland, 2006; Khurana et al., 2010). The risk in this population lies in the absence of digestive symptoms in some cases, making carriers asymptomatic (Aoun et al., 1999; Takizawa et al., 2009). The importance of this group of workers in the transmission of parasitic diseases has been emphasized by several authors (Tsega & Nadew, 1972; Sahlemariam & Mekete, 2001; Dagnew et al., 2012). This study aims to assess the prevalence of Blastocystis sp. in cooks in the Fez-Meknes region, who go to the Parasitology-Mycology laboratory of the Moulay Ismail military hospital in Meknes, for medical examinations in routine.

This is an analytical cross-sectional study carried out in the Parasitology-Mycology laboratory of the Moulay Ismail Military Hospital in Meknes, it was conducted on 200 asymptomatic persons (apparently healthy), spread over a period of 2 years from 03/01/2019 to 11/02/2021. In our study, we included all the stool samples emitted by the kitchen staff of the various military units in the Fez-Meknes region, as part of periodic systematic screening. Three fecal samples were taken from each patient in a clean plastic container. The samples were examined for the presence of intestinal parasites.

Each coprological sample was subjected to a macroscopic examination and microscopic in the fresh state (a pea of stools diluted in physiological water), after staining with Lugol's iodine and after concentration according to the Ritchie method modified and Bailenger. Occasionally, the rapid antigenic test for the diagnosis of Giardia intestinalis (G. intestinalis) and microsporidia has been performed. The x10 and x40 objectives were used for the detection of eggs and larvae of helminths, cysts and trophozoites of protozoan parasites.

Blastocystis sp. positivity has been accepted when the parasite count is greater than or equal to 5 elements per field when microscopically examined at 40x magnification (Nimri, 1993). The results of the macroscopic and microscopic analyzes of the PES were collected from the registers of the service. All results were entered using Microsoft Office Excel 2010 software and processed by IBM SPSS Statistics 21.0 software.

The study was retrospective. All data were collected from registers available at the Parasitology Mycology Laboratory of the Moulay Ismaïl Military Hospital in Meknes. The authors did not have any contact with the patients. The stool samples received previously were within the framework of routine care: screening for intestinal parasite carriage in cooks without any additional procedure. It has been taken care of to maintain patient anonymity. So the authors have an approbation of ethics committee.

During the study period (01/03/2019 to 02/11/2021), we included 200 PES of asymptomatic cooks (192 Men and 8 Women). The mean age of the participants was 37.5 ± 3.245 years, with extremes of 30 and 45 years. The largest food handler age group was 35 – 39 years (68.5 %).

Fecal parasite testing was positive in 88 individuals, which corresponds to an overall prevalence rate of 44 %. The prevalence of intestinal parasitism in male cooks is higher compared to that observed in female cooks 94.32 % versus 5.68 %. No significant statistical differences regarding parasitic infections related to gender (P=0.284) or age groups (P=0.792) were observed. The results of the study are shown in Table 1.

The intestinal parasites identified in our study all belong to the protozoa, the latter are represented respectively by the Amoeba (42.48 %) followed by the Blastocystis (30.97 %) then the Flagellates (26.54 %) (Table 2).

Blastocystis sp., Entamoeba coli (E. coli), Dientamoeba fragilis (D. fragilis) and Endolimax nanus (E. nanus) were the most identified protozoan species in our study with respectively 30.97 %, 23.90 %, 22.12 % and 14.16 % (Table 2). Among the pathogenic or potentially pathogenic parasites, we note the presence of D. fragilis with a frequency of 22.12 %, followed by G. intestinalis and Entamoeba hystolitica (E. hystolitica)/Entamoeba dispar (E. dispar) with the same prevalence rate of 1.77 %.

The parasitic association is recorded in 25 cases, or 12.5 % of the cooks tested, made only of a combination of protozoa. The species identified are found alone (monoparasitism) in 71.60 % or in double bond (biparasitism) in 28.41 % of infected persons. The bi-parasitic association between D. fragilis + Blastocystis sp. is the most important, it represents 12.50 %, followed by E. coli + E. nana with a rate of 5.68 %, then we find E. coli + Blastocystis sp. with a frequency of 3.41 %. E. nana + Blastocystis sp. occupy the fourth position with a percentage of 2.27 % and finally we find E. nana + D. fragilis, E. coli + D. fragilis and C. mesnili + D. fragilis with a rate of 1.14 % for each of them (Fig. 1).

Fig. 1.

The overall prevalence of Blastocystis sp. infection is 17.5 % (35/200). The rate of infection with this parasite is higher in men (97.14 %) than in women (2.86 %). However, no significant differences between infection with Blastocystis related to sex (P=0.706) or age groups (P=0.888) were observed (Table 3).

Blastocystis sp. is the most frequently encountered protozoan in our study. It represents 39.78 % of those infected. It is associated in 48.57 % of cases with another intestinal parasite. D. fragilis found in 64.71 % of co-infections followed by E. coli, E. nana and P. boutschlii with 17.65 %, 11.76 % and 5.88 % respectively (Fig. 2).

Fig. 2.

Our study series is composed of 192 men and 8 women, this very low female representation is due to the fact that most military structures employed men. In fact, several studies have found no significant difference in parasite infection rates between the two sexes. In our series, the average age of the participants was 37.5 ± 3.245 SD. Data on education level, place of residence, and economic status were not collected.

In the present study, the PES was positive in 88 patients, for an overall parasitism prevalence rate of 44 %. This rate of parasitism is almost identical to that recorded Addis Abeba in Ethiopia (45.3 %) (Aklilu et al., 2015). However, it is higher than the results of other studies which have reported: 29.3 % in India (Ghosh et al., 2014), 23.7 % in Kenya (Damen et al., 2015), 20.11 % in Saudi Arabia (Haouas et al., 2021), 14.3 % in Ghana (Abaka-Yawson et al., 2020), 21.5 % in Tunisia (Masmoudi et al., 2012), 28 % in Algeria (Belkessa et al., 2021), 17.9 % in France (Rousset et al., 1993), 19.3 % in Iran (Teimouri et al., 2021) and 14.5 % Northern Ethiopia (Gezehegn et al., 2017).

The differences in the prevalence reported in various studies may be related to several factors such as socioeconomic status, climatic conditions, poverty, personal and community hygiene, the population studied, and the year in which these surveys have been carried out.

The prevalence of parasitic infection shows a clear male predominance, 94.32 % versus 5.68 %, but without statistical significance (P = 0.284). This difference can be explained by the fact that the majority of military structures employed men. Therefore, we cannot draw conclusions based on gender. Moreover, several studies have not found a significant difference in the rates of parasitic infection between the two sexes (Incani et al., 2017)

Age groups analysis (Table 1) revealed that the prevalence of intestinal parasitic infections was 12.5 % among subjects aged 30 – 34 years (11/88), 69.32 % in the group aged 35 – 39 years (61/88), and 18.18 % in the group aged 40 – 45 years (16/88). These results no showed any significant association (P = 0.792) between age and intestinal parasitic infection.

Protozoa are the only parasitic group identified in our series, and they are represented by 54.54 % of Amoebas, 39.77 % of Blastocystis, and 34.10 % of flagellates of all parasitized subjects. Blastocystis sp. is the most widely detected parasite in our study population, with a prevalence of 39.77 %, followed by E. coli (30.68 %). These results corroborate those from the literature since it is accepted that Blastocystis sp. is often recorded as being the parasite most frequently encountered in the stool, followed by non-pathogenic protozoa such as E. coli or E. nana (Sebaa et al., 2021; Heydari-Hengami et al., 2018; Tan, 2008) (Table 2). The prevalence of Blastocystis sp. recorded in our study series (39.77 %) is very close to that recorded in Egypt (35.5 %) (Fathy, 2011), but it is lower than the results of other studies carried out in a population of food handlers in Tunisia (13 %) (Abda et al., 2017), Iran (24.3 %) (Heydari-Hengami et al., 2018). In contrast, surveys of school children in Senegal, Morocco, and Egypt reported prevalence rates of Blastocystis sp. of 100 %, 33.4 %, and 33.3 %, respectively (El Safadi et al., 2014; Rahmouni, 2010; Rayan et al., 2007).

Concerning co-parasitism, Blastocystis sp. is associated with another parasite in 48.57 % of cases. The most frequent association combines Blastocystis sp. and D. fragilis with a frequency of 64.71 %. Our results are correlated with those from the literature which have shown that the most common co-infections are those between protozoa and that biparasitic infection between Blastocystis sp. and D. fragilis is the most mentioned (Rahmouni, 2010; Piubelli et al., 2019). This co-infection can be explained by the fact that these two parasites have the same mode of transmission. Recent studies have reported that there is a significant association between co-infection with Blastocystis sp. and D. fragilis and the gastrointestinal symptoms (Maas et al., 2014; David et al., 2015; Piubelli et al., 2019). D. fragilis is the most detected pathogenic parasite in humans (Kallel et al., 1999; Dickinson et al., 2002; Piubelli et al., 2019) with a prevalence varying between 0.9 % and 82.9 % depending on the country, the diagnostic method and the population studied (Preiss et al., 1990; Ögren et al., 2016). It should be noted that the presence of parasitic associations shows a low level of sanitary, food and fecal hygiene as well as unfavorable living conditions of these subjects (El Moutaallik Billah, 2019). The predominance of co-infection with protozoa is explained by the similarity of risk factors and transmission modalities of these parasites (Devera et al., 1998; Dupouy-Camet, 2000).

Blastocystis sp. is the most common protozoan found in PES in both symptomatic and asymptomatic patients (Mohamed et al., 2017; Kataki et al., 2019), with prevalence ranging from 55 to 100 % in developing countries and 7 to 50 % in developed countries (Lhotská et al., 2020; Wakid et al., 2022). The presence of this protozoan in PES could be an indicator of poor personal hygiene and the existence of other parasites (Yaicharoen et al., 2006; Kataki et al., 2019). The identification of this parasite is done by several methods, namely the optical microscope, culture or molecular approaches such as PCR (Polymerase Chain Reaction). The comparisons made between these detection methods globally confirm the greater sensitivity of molecular methods compared to microscopic and cultural methods (Devera et al., 1998; Dogruman-Al et al., 2010). The transmission of this parasite takes place mainly by the fecal-oral route after direct or indirect contact with objects, food products (fruits, vegetables, salads) raw badly washed, or drinking water polluted by human or animal excreta. In addition to these risk factors for transmission of blastocystosis, there are food handlers and especially cooks with poor personal hygiene who can be potential sources of propagation of this protozoan (Idowu & Rowland, 2006; Khurana et al., 2010). The risk in this population lies in the absence of digestive symptoms, in some cases, causing carriers to be asymptomatic (Takizawa et al., 2009). The importance of this group of workers in the transmission of parasitic diseases has been emphasized by several authors (Sahlemariam & Mekete, 2001; Dagnew et al., 2012). The absence of gastrointestinal symptoms in some cases can be explained by the presence of virulent and other non-virulent species of this protozoan (Fouad et al., 2011). The pathogenicity of Blastocystis sp. remains controversial (Tan et al., 2010; Osman et al., 2016), although numerous clinical and epidemiological studies have examined this pathogenic potential in symptomatic and asymptomatic patients (Patino et al., 2008; Tan, 2008). In this context, some authors have shown the association of this microorganism with certain gastrointestinal symptoms, particularly in immunocompromised people, in particular, patients with AIDS and cancer because it is considered to be an opportunistic pathogen (Patino et al., 2008) and they have suggested a positive correlation between the density of the parasite and the symptoms (Kaya et al., 2007), on the other hand, other authors have denied this pathogenic significance and confirmed that Blastocystis sp. is a commensal organism (Sun et al., 1989; Kataki et al., 2019). Other recent genetic analyzes have shown the existence of 10 different subtypes (STs) of Blastocystis in humans noted ST1 to ST9 and ST12 (Maloney et al., 2021), this genetic diversity, supports the hypothesis of virulent species and non-virulent of this protozoan (Wakid et al., 2022).

Our results showed a high prevalence of protozoan parasites in the kitchen staff population, Blastocystis sp. being the most predominant protozoan. These asymptomatic cooks will be considered as reservoirs of parasites, in particular of Blastocystis sp. and therefore a source of infection in those around them. Consequently, preventive measures are essential, in particular by sensitizing the populations by insisting on fecal hygiene, the good maintenance of toilets, the proper treatment of water and food intended for consumption, and the treatment of infected people in order to fight effectively. against infestation by this protozoan in particular and other parasites in general.