Impact of the season and prevalence of intestinal parasitosis at the Notre Dame de l’Espérance University Hospital Center, Democratic Republic of the Congo

Introduction

Intestinal parasitic infections are serious diseases worldwide. However, doctors working in these regions tend to give them little attention due to the commonality of their occurrence. As a result, they are rarely a reason for regular consultation and are often neglected.^1,2 Although they attract little interest today compared to diseases such as AIDS, tuberculosis, malaria, and onchocerciasis, they remain a public health issue in tropical and impoverished areas.³

Climatic conditions are one of the main factors that contribute greatly to the spread of intestinal parasitic infections, by increasing their transmission and perpetuating the parasitic cycles.⁴

According to World Health Organization (WHO) estimates, more than three billion people are affected, with 450 million severely ill; of these, over 50% are school-aged children.⁵ The global prevalence is 35.8% in the world population.⁶ These diseases have disastrous health, social, and economic consequences for more than one billion people.⁶

In Africa, a study conducted in Morocco in 2019 among migrants from sub-Saharan Africa (Equatorial Guinea “30.6%”, Côte d’Ivoire “16.6%”, Senegal “9.29%”, Cameroon “8.01%”, with the remaining patients coming from Niger, Togo, Congo, Burkina Faso, Mali, Gabon, and Benin “35.5%”) showed a prevalence of 43.18% for intestinal parasitic infections. Among these individuals, 63.15% were infested with various digestive parasites simultaneously.⁷ A study conducted Algeria showed a highly significant difference of prevalence between symptomatic (82.3%) and asymptomatic subjects (14.9%), with the majority attributable to protozoan infection. The most common species in the symptomatic subjects were Blastocystis spp. (43.8%), Entamoeba histolytica/dispar (25.4%) and Giardia intestinalis (14.6%) and more rarely Enterobius vermicularis (02.1%), Teania spp. (0.6%) and Trichuris trichiura (0.2%), while in asymptomatic population Blastocystis spp. (8%), Entamoeba coli (3.3%) and E. histolytica/dispar (2.5%) were the most common parasites detected with no case of helminth infection.⁸ Another study conducted among schoolchildren in the Republic of Congo revealed a prevalence of intestinal parasitosis of 25.7%, with the most frequent parasites being: Entamoeba coli (52.2%), Ascaris lumbricoides (13%), and Endolimax nana (10.9%).⁹

In the DRC, data on intestinal parasitosis are poor. The few available data that parasitic infections pose a public health problem due to multiple crises that have led to displacement and a lack of potable water, food hygiene, and sanitary facilities.¹⁰ A study conducted in Bukavu in 2016 on the impact of seasons on intestinal parasitic infections showed a prevalence of 94%. The identified helminths, in decreasing order of frequency, were: S. mansoni (30.6%), S. stercoralis (21.3%), Ancylostoma duodenales (13.6%), A. lumbricoides (12.6%), T. trichiura (9.0%), and T. saginata (6.6%). Identified protozoa included Pentatrichomonas hominis (13.69%), Entamoeba histolytica (6.75%), and Giardia lamblia (4.76%).¹¹ According to a study conducted in Kinshasa more than half of the diagnosed individuals were infested with A. lumbricoides at 58.3%, followed by 30% of individuals hosting E. histolytica, and A. duodenales was isolated in 11.7% of the diagnosed individuals.¹²

The East Kasai region is dominated by a humid tropical climate with two seasons (dry season from 15^th May to 15^th August and rainy season from 15^th August to 15^th May).¹³ The population living in the eastern part of its capital, Mbujimayi, and the surrounding villages, served by CHUNDE, is poor and lives in very poor hygienic conditions. We have not identified any study that could inform us about the prevalence of intestinal parasitic infections here. The prevalences of intestinal parasitosis as well as the factors that influence them are poorly documented in East Kasai.

The prevalence of intestinal parasitic infections is likely very high at CHUNDE and may be associated with the season.

Methods

Study results

Characteristics of the study population

From January 1, 2020, to December 31, 2021, 187 patients were included in our study.

Table 1 summarizes the demographic characteristics: Among the 187 patients included in our study, 94 were female and 93 were male. The sex ratio was one woman for one man. A total of 158 patients were adults [≥18 years <70], 20 were children [<18 years], and 9 were elderly [≥70 years]. The mean age was 41.68 ± 17.95 years. The youngest patient was 2 years old, and the oldest was 77 years.

Table 1. Demographic characteristics of patients undergoing direct stool examination between 2020 and 2021.

	Frequency (N=187)	%
Sex
Female	93	49.73
Male	94	50.27
Age groups
Children (<18 years old)	20	10.69
Adults (18-70 years old)	158	84.49
Senior adults (˃70 years old)	9	4.81
Mean age	41.68±17.95

Figure 1. Frequency of different types of intestinal protozoa.

Frequencies of intestinal helminths

As shown in Figure 2, A. lumbricoides/dispar was the most frequent helminth, with 52 cases (27.81%), followed by S. mansoni, with 7 cases (3.74%), A. duodenale, with 3 cases (1.60%), and E. vermicularis, with 2 cases (1.07%).

Figure 2. Frequency of different types of intestinal helminth infections.

Frequency curves of intestinal parasitic infections

Figure 3 shows the evolution of frequency of intestinal parasitosis by year (2020 and 2021). It allows to analyze this evolution in relation to the season (dry season: from 15/5 to 15/8 and rainy season: from 1/1 to 14/5 and from 16/8 to 31/12).

Figure 3. Frequency curves of intestinal parasitic infections in 2020 and 2021.

In 2020, the frequency of intestinal parasitic infections was high, with peak values during the dry season (83-100% in May, June, and July) and in October. In 2021, the frequency also remained high, particularly with peak values observed during the dry season (87-90% in May and June) and in September.

Frequency curves of intestinal protozoan infections

Figure 4 shows that the frequency of intestinal protozoa was high in both 2020 and 2021. In 2020, two peaks of this frequency were observed during the dry season (100% in May and July). In 2021, two high values of this frequency, 80% and 85%, were observed in May and September, respectively.

Figure 4. Curve of the frequency of intestinal protozoa in 2020 and 2021.

Frequency curves of intestinal helminthiasis infections

The frequency of intestinal helminthiasis was higher in 2021 than in 2020. In 2020, three high frequencies were recorded during the dry season (66% and 40% in May and July) and in October (74%). In 2021, three other high frequencies (72%, 56%, and 60%) were recorded in February, June, and October, respectively (Figure 5).

Figure 5. Curve of the frequency of intestinal helminthiasis in 2020 and 2021.

Discussion

In this study, we estimated the prevalence of intestinal parasitosis in general, as well as the prevalence of different types of intestinal parasitosis, among patients who underwent direct stool examination at CHUNDE in 2020 and 2021. These patients were aged between 2 years and 77 years, with an odds ratio of one woman for every man. In this study, the overall prevalence of intestinal parasitosis was high (75.40%). Intestinal protozoa (60.69%) were more frequent than helminths (35.29%). The most prevalent protozoa were E. histolytica/dispar (55.08%), P. hominis (9.09%), and G. lamblia (6.24%). The most common helminths were A. lumbricoides (27.81%), S. mansoni (3.74%), A. duodenale (1.60%), and E. vermicularis (1.07%). Polyparasitism was observed in 24.13% of patients, with the combination of E. histolytica and A. lumbricoides being the most frequent (14.44%). Intestinal parasitosis were particularly prevalent in children (95.00%) and elderly adults (88.89%), and more frequent among women (78.49%) than men (72.34%). Prevalence was higher, although no statistically significant association was observed between season and parasitosis prevalence.

The overall prevalence of intestinal parasitosis was 75.40%. The prevalence of intestinal protozoa and helminths was 60.69% and 35.29%, respectively. The most prevalent intestinal protozoa were E. histolytica/dispar (55.08%), followed by P. hominis (9.09%) and G. lamblia (6.24%). The most prevalent intestinal helminths were Ascaris lumbricoides (27.81%), followed by S. mansoni (3.74%), A. duodenale (1.60%), and E. vermicularis (1.07%). Worldwide, a study in Brazil estimated the prevalence at 10.8% (95% CI: 8.6–13.4). Endolimax nana was the most frequent parasite (4.8%), followed by E. histolytica/dispar (1.7%). In Africa, the prevalence of intestinal parasitosis remains high in many studies. Studies in Ethiopia and Morocco showed high frequencies of intestinal parasitosis but lower than ours, with prevalences of 52.9% and 43.18%, respectively.^7,14,15

In Guinea the prevalence of intestinal parasitosis is 52% with A. Lumbricoides (Figure 3), hookworm, and S. mansoni being the helminths most frequently found, with a prevalence of 15% (95% CI: 12,18), 6% (95% CI: 5,8), and 5% (95% CI: 3,7), respectively. Among protozoans, E. histolytica was predominant with a prevalence of 4% (95% CI: 3,5). The young children were less infected, with a prevalence of 37 % (95 % CI: 26,50) when compared to adults. The pooled prevalence of soil-transmitted helminth infections was 12%.¹⁶

In the DRC, according to a 2019 study conducted in Kinshasa More than half of the diagnosed individuals were infested with A. lumbricoides at 58.3%, followed by 30% of individuals hosting E. histolytica, and A. duodenales was isolated in 11.7% of the diagnosed individuals.¹²

In all these studies, the prevalence of intestinal parasitosis remains high, with intestinal protozoa being more frequent than helminths. We note some differences, that we attribute to the fact that these studies were conducted in different regions with varying hygienic conditions. Specifically, studies in Tunisia provide percentages of intestinal helminths and protozoa relative to the total number of people affected by intestinal parasitosis, while our study shows the actual prevalence of each specific parasite type within the total population studied.

45 patients (24.13%) were infested by multiple intestinal parasites simultaneously, with 19.79% combining at least one helminth and one protozoan. The most frequent combination was E. histolytica and A. lumbricoides, with 27 cases (14.44%). Other studies have noted cases of polyparasitism. A study conducted in Benin between 2005 and 2013 by Sissinto et al. showed a polyparasitism rate of 17.4% (3.09% of the total study population). The most common associations were Blastocystis hominis + E. histolytica/dispar (20.1%), Entamoeba coli + E. histolytica/dispar (17.2%), and B. hominis + Endolimax nana (11.7%). In Morocco, Zouitni reported a polyparasitism rate of 63.15% (27.2% of their study population). In the DRC, Woolf K. et al. reported a polyparasitism prevalence of 23.41%. We note similarities between our polyparasitism rate and those found in the last two studies mentioned.^7,10,17

Intestinal parasitosis were more frequent among children (95.00%) and elderly adults (88.89%). They were also more frequent among women (78.49%) than men (72.34%). In their study among children under 5 years old in Kivu, DRC, Woolf K. et al. recorded a prevalence of intestinal parasitosis of 94%, very close to the rate recorded in our study for children. In Guinea a meta-analysis showed a high prevalence of intestinal parasitosis among children under (37% of cases). A study in Bangui by Lango Y. et al. showed a higher prevalence of intestinal parasitosis in women (35.10%) compared to men (32.89%).^3,10,16,18

There was no statistically significant association between season and the prevalence of intestinal parasitosis in general, nor with intestinal helminthiasis or protozoan infections. In the DRC, a study conducted in Sake (Kivu) among 504 children under 5 years old showed no association between season and the prevalence of intestinal parasitosis.¹⁰ These results underscore the need to study the behaviors adopted by the population during different seasons to identify factors that directly affect the prevalence of parasitosis. As highlighted in the introduction, this region is known for its poor hygiene conditions, with frequent shortages of drinking water and poor waste management, especially for fecal matter.

The strength of this study lies in providing prevalence data for different types of intestinal parasitosis in Kasai Oriental, where such data had not been published until now. The weakness of this study lies in the fact that the direct stools examination differentiate E. histolytica from E. dispar; The techniques of enrichment of stools specific to certain parasites were not carried out and certain intestinal parasites, such as S. stercoralis and Schistosoma, require serological tests in addition to the examination of stools because they are often not detected by this examination. We believe that the prevalences of certain intestinal parasites could be underestimated. The small sample size and selection bias (hospital-based, symptomatic patients), limiting generalizability. The lack of data on confounding factors (socioeconomic status, water, sanitation).

The prevalence of intestinal parasitosis among symptomatic patients at CHUNDE, East Kasai, is considerably higher than reported in other African and international studies. This difference is due to the fact that the study took place in symptomatic patients. The predominance of protozoa over helminths is consistent with other studies, though the distribution of specific species varies by region. Polyparasitism was frequent and underscored the heavy burden of infection in this population. Seasonal variations were noted, but without statistical significance, suggesting that transmission is consistently high year-round.

Conclusion

This study provides the first published prevalence data on intestinal parasitosis in East Kasai. The prevalence of intestinal parasitosis was higher among symptomatic patients at CHUNDE, with protozoa more frequent than helminths. Polyparasitism was common. There is no statistically valid association between the season and the prevalence of intestinal parasitosis.

Author contributions

Disclosure statement

The authors are employees of the University of Mbujimayi, all in training at its medical faculty and assigned to its University Hospital Center Notre-Dame de l’Espérance.

Ethics and consent

This study received approval from the ethics committee of the University of Mbujimayi on N52/CEUM1209 of 11th December 2019. It was conducted in accordance with the requirements of good clinical practices and the principles of the Helsinki Declaration of the World Medical Association, along with any subsequent relevant amendments. All patients who have participated in this study have provided their written informed consent by signing a written document, the consent form.

Context