Nature, Period, and Study Setting

This was a cross-sectional and descriptive study conducted over a period of two months, from May to June 2023, in three randomly chosen schools in the city of Kisantu, Kongo Central.

Sample Size

The sample size was calculated using Fisher’s formula:

n = Z² x p (1-p)/d²

n = sample size

Z = 1.96 (confidence coefficient)

p = previous prevalence

d = 0.05 (margin of error or precision gap).

Due to possible non-respondents, 10% was added to the calculated number. We used 6.6% as the scabies prevalence in the DRC. The calculated sample size was n = (1.96)² x 0.178 x 0.822/(0.05)² = 224. Including the 10% non-response rate, the final sample size was 247 students, distributed proportionally across three schools.

Patient Selection

Students were selected based on anamnestic and clinical criteria. Included in the study were students aged 3 to 15 years, enrolled during the study period, who had scabies, and whose verbal assent and informed verbal consent from their guardians were obtained for the interview. Students of the same age range who were not affected by scabies were excluded from the study. Students aged 3 to 15 years with scabies but whose parents did not give verbal informed consent for the interview were also excluded.

Selection of Schools and Classes

Considering the locations of the communes and the limited resources for data collection, we randomly selected three schools and their classes from three different neighborhoods in the city of Kisantu. We chose four classes per school. For the first school, we selected students from kindergarten and the first three primary grades. For the second school, we chose students from the 3^rd, 4^th, 5^th, and 6^th primary grades. For the third school, we targeted students from the orientation cycle and the first three years of secondary education.

Data Collection Technique

Data was collected using a pre-established survey form. The collected data was then organized into variables of interest, including three parameters: sociodemographic characteristics (age, sex, school level, family head’s level of education, and socio-economic position index of the family head), history (contact with infected individuals, contamination source, number of people in the household who scratch themselves, shared beds, atopic history, frequency of bathing, frequency of changing clothes), and clinical characteristics of scabies (functional signs, lesion sites, types of lesions, nutritional status).

To conduct the study, a request letter was submitted to the school authorities. With their positive response, we conducted awareness and information sessions for school administrators and the students’ guardians. Data collection was performed through interviews with students in different classrooms. Some photos of the skin lesions were taken of children who had scabies, while strictly respecting their anonymity.

Study Variables

The variables of interest included sociodemographic parameters, history, and clinical data.

Sociodemographic Characteristics

The LE was rated from 1 to 7 (University: 7, Institute: 6, Graduate: 5, Vocational studies (state diploma): 4, Vocational studies (6^th grade): 3, Primary school certificate: 2, Less than primary school certificate: 1).

The PC of the family head was rated from 1 to 6 (Executives, senior managers, directors: 1; Intellectual and scientific professions (engineers, doctors, professors, lawyers, etc.): 2; Intermediate professions (technicians, nurses, accountants, police inspectors, etc.): 3; Administrative employees (secretaries, receptionists, clerks, etc.): 4; Service and sales staff (chefs, waiters, hairdressers, firefighters, guides, salespeople, etc.): 5; Farmers, fishermen, etc.: 6; Unskilled workers and employees (porters, street cleaners, delivery people, domestic helpers, street vendors, etc.): 7.

SEPI = Socio-Economic Position Index = family head’s age in years – 6 x LE – 4 x PC + 55. SEPI was distributed as follows: lower class (1–35), lower-middle class (36–54), middle class (55–67), upper-middle class (68–80), and upper class (over 80).

Environmental Characteristics

Pruritus Periodicity

Nocturnal: The pruritus is noticeable at night or at dusk.

Diurnal: The pruritus is felt during the day.

No specific timing: The pruritus is perceived at any time by the patient.

Statistical Analyses

The collected data was encoded and cleaned using Microsoft Excel. Descriptive analyses (frequencies, means), Pearson correlation, and uni- and multivariate analyses were performed using SPSS v.20 and Epi Info v.7 to standardize the data.

Ethical Considerations

From data compilation through to data processing, confidentiality and ethical considerations were in accordance with the Helsinki protocol. The use of the results of this study was strictly limited to its intended use.

Epidemiology

General Characteristics

The average age was 2.16 ± 0.59 years; the median was 6 years (ranging from 3 to 15 years), and the sex ratio was 1.22.

Sociodemographic Characteristics

Table 1 indicates that the male sex was more represented in 55.0% of cases, and the age group of 6 to 12 years accounted for 67.1%. The children were in primary school in 98.8% of the cases, and the socioeconomic position index of the head of the family was 49% in the middle class.

Table 1: Distribution of respondents depending on sociodemographic characteristics.

Environmental Characteristics

In a statistically non-significant manner, Table 2 reveals the following information.

Table 2: Distribution of the respondents depending on environmental characteristics.

The notion of contagion was high in 70.68% of the cases; most children had a family lifestyle in 88.7%; the source of contamination was attributed to a close relative in 61.4% of the cases; the largest number of people in the child’s immediate surroundings varied from 4 to 6 in 53.41% of the cases. Regarding the number of people per bed, it ranged from 2 to 3 in 40.16% to 41.73% of the cases; the majority of surveyed children bathed 3 to 4 times a week in 26.1% of the cases and wore the same clothing for two to three days without washing in 40.16% and 41.7% of the cases.

In cases of scabies, the intensity of itching was significantly related to the number of people sleeping in the same bed (p = 0.004) (Table 3).

Table 3: Distribution of the respondents depending on the number of people sharing the same bed and the notion of scratching.

Clinical

Medical history

Only age was significantly associated with atopy in scabies-affected children (p = 0.001), specifically with the predominance of asthma across all age groups and allergic rhinitis in those aged 6 to 12 years (Table 4).

Table 4: Distribution of the respondents depending on atopy history by sex and age.

Functional Signs (Intensity and Periodicity of Itching)

The intensity of itching was significantly associated with its periodicity. Severe and mild itching did not have a specific timing (53.92% and 58.73%); however, moderate intensity itching was more nocturnal (45.24%) (Table 5).

Table 5: Distribution of the respondents depending on the intensity and timing of itching.

Lesional Types and Their Locations

Scratch marks were more frequent in 35.7% of the cases, while the intergluteal folds were the most affected areas of the body in 31.3% of the cases (Table 6).

Table 6: Distribution of the children depending on lesion type and site.

Regardless of the age group, scabies was more frequent among children with a normal weight (p = 0.000) (Table 7).

Table 7: Distribution of the respondents depending on body mass index.

In the univariate analysis, aside from the concept of contagion and the number of people scratching in the surroundings, all other variables are significantly associated with the occurrence of scabies (p ≤ 0.05). In contrast, in the multivariate analysis, all variables considered are statistically non-significant.

Epidemiology

In this study, the prevalence of scabies was 24.9%. This result is close to those by Ahmed et al. in Saudi Arabia [20] with 27.1% and Javed et al. in Karachi [21] with 23.9%, in contrast to observations from Kuwait [22], Ethiopia [23–25], Egypt [26], Nigeria [27], Benin [13], and Cameroon [4], which reported prevalences of 3%, 9.3% to 12.9%, 4.4%, 4.4%, and 17%, respectively. The overcrowded living conditions of our populations, poverty, ignorance regarding skin care, and the average socio-economic status of the head of the family could explain the increase in the prevalence of scabies in our environments.

The average age was 2.16 ± 0.59 years, with a sex ratio of 1.22. Unlike the Egyptian [28], Central African [29], Ethiopian [23], and Congolese [8] studies, we observed a male predominance. This finding was also noted by Mongbo et al. in Benin, where 52.4% of the cases were male [13]. Aside from the sample size, which includes the adult population in other studies, the male predominance in this study could be attributed to the more active nature of young boys, who may not always be prompt in maintaining daily hygiene. Additionally, girls tend to be more attentive to their overall health and skin condition in particular.

In this study, most of the children were aged between 6 and 12 years, attending primary school, and their parents had an average socio-economic status. This age distribution is similar to that reported by Bisrat et al. [23] and Ngolo et al. in Goma, DRC [8], but differs from the findings of Mongbo et al. in Benin [13], who noted a predominance of ages between 0 and 9 years. Regarding educational level, students in grades 1–4 (57.8%) were more numerous in Ethiopia [23].

Our observation about the living environment aligns with that by Bisrat et al. [23], who reported a rural setting in 60.35% of cases, despite the fact that the socio-economic status of the parents was average to low. Concerning the children’s environment, the notion of contagion was high in 70.68% of cases, with a family lifestyle in 88.7%; the source of contamination was a close relative in 61.4% of cases. The largest number of people in the child’s immediate surroundings ranged from 4 to 6 (53.41%).

Regarding the number of people per bed, it ranged from 2 to 3 (40.16% to 41.73%); the majority of surveyed children bathed 3 to 4 times a week (26.1%) and wore the same clothing for two to three days without washing it in 40.16% to 41.7% of cases.

Although lower than our result, the notion of contagion was around 20.88% [23] in Ethiopia. The infrequent changing of clothes was also reported by Ethiopian [23,30,31] and Pakistani authors [32]. Samina et al. noted that nearly all children with scabies (31 out of 40) shared a bed with someone else, as did Bisrat et al. in 89.18% of cases [23,31]. Many children bathed 3 to 4 times a week in our study (26%), similarly to Pakistan, where 27 out of 40 children bathed that often [31]; this contrasts with Ethiopia, where children bathed less than once a week [23]. Regarding the frequency of changing clothes, our findings align with those by Bisrat et al. and Samina et al. in Pakistan, who reported that 66.24% of children wore the same clothing for up to a week, with 36 out of 40 children in their study [23,31].

The poverty and precarious conditions observed in developing countries, along with close and prolonged human contact, and infrequent changing of clothes—despite having multiple baths a day (as these clothes can harbor the parasite)—are conditions that favor the proliferation of the mite, Sarcoptes scabiei var. hominis. It moves in the presence of warmth (at night while sleeping), burrowing tunnels in the epidermis while depositing its allergenic saliva that contains its larvae [12], leading to itching. The parasite can also live on parts of clothing [24,26] in areas of friction or “bastion zones” (collars, armholes, wrist areas, waistbands, and the bottom of the pants). This last location was found to be the most frequent in the present study. Daily personal hygiene and reducing the number of people per bed could help decrease infestation.

Clinical

Age was significantly associated with atopy in scabies-affected children (p = 0.001), specifically with the predominance of asthma across all age groups and allergic rhinitis in those aged 6 to 12 years [8]. Atopy is a genetically determined hypersensitivity to environmental allergens, such as dust mites [33–35]. This predisposition is responsible for xerosis, due to the alteration of the skin’s mechanical barrier function; thus, atopic skin dryness may favor acute and chronic clinical expressions of scabies in terms of more significant pruritus and inflammatory reactions.

The intensity of pruritus was significantly associated with nocturnal periodicity; severe and mild pruritus did not have a specific timing (53.92% and 58.73%); moderate intensity pruritus was more nocturnal (45.24%). Samina et al. (55%) and Shama et al. in India (69.5%) reported nocturnal pruritus without a specific timing in 35% and 26.3% of cases, respectively [31,36]. Pruritus in human scabies is familial and has a nocturnal or evening periodicity.

Scratch marks were more frequent in 35.7% of cases, with the intergluteal folds being the most affected body parts in 31.3% of cases. In Ghana, the predominant lesion site was the wrists and/or the interdigital spaces (22.7%), followed by the intergluteal fold in 22% of cases [37]. Scratch marks are a consequence of pruritus, and their primary location in this study may be due to close contact between the intergluteal skin and the parasite, which could be embedded at the seam of the pants and/or underwear in conditions of likely poor hygiene.

Significantly, there was an association between age and the nutritional status of children with scabies. Regardless of age group, scabies was more frequent in children with normal weight (71%), while 24% were underweight (p = 0.000). Scabies is generally associated with overcrowding, poverty, and malnutrition [35].

Regarding table 8, in univariate analysis, this study revealed that the factors associated with scabies among the students were age, sex, the educational level of the head of the family, the notion of contact and source of contamination, the number of people in the vicinity and those who scratch themselves in the vicinity, the number of people sharing the same bed, atopy, the frequency of bathing and changing clothes, and body mass index (p ≤ 0.05) (Table 8). Our observations are similar to those of Bisrat et al. [23], Abebaw et al. [34], all in Ethiopia, Doaa et al. in Egypt [26], and Birjandi et al. in Ghana [37] regarding sex, the educational level of the head of the family, the fact of sleeping multiple people in the same bed, the notion of contact, and bathing frequency, which, however, was not associated with scabies according to an Ethiopian meta-analysis [34]. Scabies was more frequent among boys in our study (55%). This finding is similar to that of Hiwot et al. in southern Ethiopia [35], unlike that of Birjandi et al. in Ghana [37]. The multivariate analysis in our study (Table 8) did not retain any statistically significant variable related to scabies.

Table 8: Factors associated with scabies in rural school settings.

Regarding age, children aged 6 to 12 years were the majority (67%). These results could be explained by the fact that between the ages of 6 and 12, children are in a phase of rapid growth. They play with their friends, particularly boys, and are consequently in close contact, which could facilitate contamination. Scabies is a common ectoparasitosis in communities, favored by close living conditions, which emerged in our study as a source of contamination from close individuals, some of whom scratch themselves, sleep in the same bed, and wear the same clothing for several days. Malnutrition is a condition that promotes the occurrence of infections similar to ectoparasitoses. A protein deficiency could lead to a keratinization defect with xerosis, associated with a disruption of the skin’s mechanical barrier function. Consequently, the penetration through the integumentary system of an allergen and/or a pathogen such as Sarcoptes scabiei var. hominis would become facilitated. The size of our sample and the research methodology could further explain the divergence of our results from those of other authors.

The socio-economic position index corresponded to the middle class for 49% of the parents of children suffering from scabies. Scabies can be observed in all social strata regardless of socio-economic level [36]. Anwar et al. noted an association between scabies, overcrowding, and socio-economic status in Saudi Arabia [38].

Limitations of the Study

Although conducted in three schools, our study does not reflect the epidemiological reality of scabies prevalence in the rural area of Kisantu. Furthermore, the short duration of the study did not allow for the expansion of our sample size.