Soil transmitted helminths infections in a rural community

INTRODUCTION

The World Health Organization (WHO) estimates that 568 million school-age children (SAC) reside in locations where soil transmitted helminths (STH) are widely transmitted^[1] and over two billion people are afflicted with one or more STHs, the most common of which are Ascaris lumbricoides, hookworm, and Trichuris trichiura.^[2] School-aged children are more likely to become infected with STH.^[1] STHs are a type of neglected tropical disease responsible for the majority of infections worldwide, primarily affecting disadvantaged populations in low- and middle-income nations^[3] in tropical regions in Africa, Asia, and Latin America.^[1] Ascaris lumbricoides infects around 1.2 billion individuals, followed by Trichuris trichiura infecting around 795 million people and Hookworm (Ancylostoma duodenale and Necator americanus) infecting around 740 million people globally.^[4,5] Ascaris and Trichuris primarily affect school-aged children,^[4] possibly because children are more exposed to contaminated soil when they play, walk barefoot, consume soil, and do not practice basic personal hygiene. ¹ However, hookworm affects both children and young adults. It causes iron deficiency anemia, protein energy malnutrition, and growth retardation.^[4]

The prevalence of helminthic infection in school-aged children makes this subgroup a strong target for helminth control programs in the general population, and schools provide good possibilities for control program implementation.^[6] While Odinaka et al.^[7] identified inadequate hand washing and male gender as risk factors for being infected with STH. Onah, 2023^[3] identified children who played with sand and those who didn’t wash their fruits before eating as a risk factor for being infected.

The prevalence of STH varies in Nigeria, between 30.3%^[7] to 52.0%.^[8] Despite various studies on the prevalence of intestinal helminthiasis in Nigeria, there are still areas, like our study area, where epidemiological data is lacking. The aim of the study was to determine the prevalence of STH and its associated risk factors. This will serve as a baseline for any future study of proposed regular deworming programs at local communities throughout the state.

MATERIAL AND METHODS

Study area: The study was conducted in the Agbeyangi community, which is the headquarters of the Agbeyangi/Gbadamu/Oshin political ward of the Ilorin East local government area. Ilorin East is a Local Government Area in the Nigerian state of Kwara. Its headquarters are located in Oke Oyi.

It has a land area of 486 km² and a population of 204,310 people, according to the 2006 census.^[9] The population of Agbeyangi consists primarily of farmers, while some work in other businesses such as driving, trade, and weaving cotton for local lamps, among others. Their major sources of water are the well and stream.

Study design: The study is a cross-sectional, community-based descriptive study. Total sampling of consenting participants^[10] was done in the community. The research was carried out between June to August, 2023

Study populations: The study population comprises infants, children, adolescents, and young adults in the community

Ethical approval: Ethical approval was obtained from the Kwara state Ministry of health, Ilorin, Kwara State, with Ethical No: ERC/MOH/2023/06/124. Signed consent was obtained from all participants, and in children assent was obtained from the parents or guardian.

RESULTS

DISCUSSIONS

Socio-demographics of the respondents show that out of 500 respondents, 51.0% (255) were males while 49.0% (245) were females. This was lower than that recorded by Onah (2023), which showed the male prevalence to be 57.3% and female prevalence to be 42.7%.^[3] Furthermore, in the study by Onah (2023), respondents fell into three age groups- 5-8, 9-12, 13-16, and 17-20 years, with group 9-12 having the highest number of participants (159, 46.5%).^[3] However, our study included infants in the community and fell into five groups 0-5, 6-11, 12-16, and 17-23 years, with group 18-25 having the highest number of participants (164, 32.8%). Adefioye et al. (2011) recorded ages 11-15 years as having the highest number of participants.^[13] The difference could be that our study was a community-based research, while Onah’s (2023) research was carried out in a school.^[3] Not wearing footwear, lack of awareness/knowledge on STH, not washing hands, and contaminated sources of drinking water were identified as risk factors for STH infestations (p<0.05) in our study in North Central Nigeria. In this study, logistic regression showed that as age increases, the risk of infection also increases (OR= 0.1, 95% CI- 0.06 - 0.17, p value <0.001). Also, not wearing footwear, lack of awareness and the source of drinking water were associated with an increase in the probability of being infected (OR= 0.02, 95% CI- 0.01 – 0.05, p value <0.001; OR= 1.05, 95% CI- 1.01-1.08, p value- 0.014; OR= 1.02, 95% CI- 0.51 – 0.45, p value <0.001), respectively. Odinaka et al. (2015) in South eastern Nigeria identified the male gender as a risk factor.^[7] Adefioye et al. (2011) in their study in South western Nigeria identified use of pit latrines, drinking of stream water, and not treating water before drinking as risks factors.^[13] Aribodor and colleagues (2023) identified lack of awareness as a risk factor for being infected with STH (OR = 0.60, 95% CI: 0.42 - 0.86, p = 0.008).^[14] Ekundayo et al. (2007) noted that in the 1980s, most authors noted on the unsanitary and common behavior of people defecating or dumping feces at garbage depots, neighbouring bushes, below bridges, along bush tracks, motor roads, river sides, and even on open fields. Minimal success was recorded in introducing latrines into rural Nigeria as many dwellings lack latrines, and public latrines are limited.^[8] However, we noted that there may be a down trend to open defecation as respondents use both pit and water closet.

The prevalence of STH in our study was 13.2% and was highest among the age group 12-17 years, as shown in our study (38, 27.94%). Hookworm was the most prevalent specie (27, 40.91%) followed by Entamoeba histolytica (19, 28.79%) and the least prevalent was S. stercoralis (8,12.12%). Infections with hookworm are common in Nigeria, particularly in children, depriving them of the essential nutrients needed for growth and development.^[15] Odinaka et al. (2015) showed 30.3% STH prevalence and similarly observed hookworm as the most prevalent specie (81, 94.2%), with the least common being A. lumbricoides (2, 2.3%).^[7] Adefioye et al. (2011) had a higher prevalence of 52.0%, highest among the age group ≥15 years, but in contrast recorded A. lumbricoides as the most prevalent (36.2%) followed by hookworm (10.5%).^[13] Ibidapo et al. (2008) recorded an overall prevalence of 83.3% with Ascaris lumbricoides (67.7%) being the most prevalent followed by hookworm (45.0%), Trichuris trichiuria (31.3%), and the least prevalent being S. stercoralis (18.0%).^[15] One of the main ways that ascariasis spreads among schoolchildren is through dirty hands. Due to their unclean play environment and frequent dipping of contaminated hands in their mouths, toddlers have also shown high positive rates for STHs.^[15] In our study the sources of drinking water played a significant role in STH transmission (p<0.05), even in cases where there is no increase in the availability of clean water or sanitation, it is recommended that Nigeria treat SAC on a regular basis, as well as other vulnerable populations like pregnant women, pre-schoolers, and people in particular occupation groups, in order to help prevent the worst consequences of infection.^[15]

Low positive rates for S. stercoralis may have resulted from the dry environmental conditions experienced between July and December, as these parasites’ ova are known to be susceptible to destruction.^[13] The variation in prevalence could also be related to differences in survey timing and season, environmental conditions, and other geographical characteristics in the studied sites. Furthermore, the most popular diagnostic techniques for detecting STH, like Kato-Katz and direct fecal smear, have poor sensitivity for S. stercoralis and occasionally may not detect it at all. Under diagnosis of threadworm might result from these diagnostic challenges, which are frequently caused by the irregular excretion of parasite larvae.^[16]

The lower prevalence may also be due to regular deworming in the community. Hence, it is imperative to constantly evaluate the prevalence of intestinal helminths among children and young adults, owing to the ill-effects posed by these parasites among the vulnerable groups.

Because intestinal helminthiasis is linked to socioeconomic status in most African countries and has a negative impact on schoolchildren’s academic performance, a comprehensive investigation of intestinal helminth infection should not be limited to children alone but should also include their parents and other communities within the local government area for effective control. Mass deworming of schoolchildren with anti-helminthic medications such albendazole or combination therapy with praziquantel should be done at least twice a year. This would substantially lower the prevalence and severity of infections. Personal cleanliness must also be promoted.

CONCLUSION

The prevalence of STH was low in our study site (13.2%), and risk factors associated with STH infestation include not wearing footwear, lack of awareness/knowledge of STH, lack of hand washing, and contaminated sources of drinking water.