Prevalence and the factors influencing soil-transmitted helminths among school age children (5-14 years age) in a rural area of Coimbatore district.

CONTEXT: Highest intensity of soil-transmitted helminthiasis (STH) is seen among school age children. AIMS: The aim of this study is to find out the prevalence and factors associated with soil-transmitted helminthic infection among school age children (5-14 years) in a rural area of Coimbatore district. SETTINGS AND
DESIGN: The study was conducted in the field practice area of the Rural Health Training Centre (RHTC) Vedapatti, Coimbatore. RHTC caters to a total population of 23,841 distributed in 14 villages. After getting ethical clearance, five of the 14 villages of Vedapatti were selected by the cluster sampling method. Totally, 819 participated in the survey conducted between November 2015 and July 2016 in the field practice area. SUBJECTS AND METHODS: Structured questionnaire was used to collect the information. Consent from parents and assent from child were obtained. Totally, 610 gave one adequate stool sample. Early morning samples were collected and transported to the laboratory within four hours. Formal ether concentration method was performed, and examination was done. STATISTICAL ANALYSIS USED: Data analysis was performed with the SPSS version 19 software. The prevalence is expressed in percentage with 95% confidence interval (CI). Univariate and multivariate analyses were performed. Strength of association was expressed in terms of odds ratio (OR) and adjusted OR with 95% CI. P < 0.05 was considered as statistically significant.
RESULTS: The prevalence of STH was 7.70% (95% CI: 5.58-9.82). Ascaris lumbricoides was highly prevalent 6.9% (4.89%-8.91%) followed by Hook worm 0.7% (0.04%-1.36%), and Trichuris trichura 0.2% (0.15%-0.55%). Mulitivariate logistic regression analysis showed that pucca houses offered protection against STH.
CONCLUSIONS: The prevalence of STH in a rural area of Coimbatore is 7.7% (95% CI: 5.58-9.82), and is continuing as a public health problem. Copyright:

INTRODUCTION

The soil-transmitted helminthes causing major illness among human beings include Ascaris lumbricoides, Trichuris trichiura, Necator americanus, and Ancylostoma duodenale.[1] STH are considered neglected tropical diseases.[2] STH affects more than one fourth of the world's population, and it is reported more in tropical and subtropical areas.[3] The greatest number of cases are occurring in sub-Saharan Africa, the Americas, China, and East Asia.[4] In India, the reported prevalence of STH infection can be striked out varied from 7.8% to 92.6%.[56789] The reported prevalence varies according to the place and time of the study conducted.

The highest intensity of soil-transmitted helminthes occur in school age children.[10] Children do not fully understand the connections between illness and behavior.[11] It has been demonstrated that children often than adults tend to go barefoot, resulting in more contact with soil, and fail to use sanitary facilities even when they are present.[12] STH infections are considered an important cause of sickness absenteeism. They are accounting for loss of 12.3% and 11.4% of disability adjusted life years in girls and boys, respectively.[13] Over 270 million preschool-age children, and over 600 million school-age children live in areas where sanitation is poor and these parasites are intensively transmitted.[14] In India, more than 241 million children are at the risk of parasitic worm infections. Ministry of Health and Family Welfare, Government of India launched the National Deworming Day (NDD)[15] on Feb 10, 2015. NDD aims to de-worm all children between the ages of 1–19 years. The tablets were supplied to children through government, government-aided and private schools, and Anganwadi centers.

When regular deworming is accompanied by appropriate sanitation and hygiene activities designed to prevent re-infection, a long-term impact can be achieved. Epidemiological studies are needed to identify the risk factors which may represent critical control points. There is no recently published article on the prevalence of soil-transmitted helminthes in Coimbatore, where open-air defecation is a common practice. As per the 2011 census, 46% of the households in Coimbatore district lack toilets. Hence, this cross-sectional study was proposed and conducted with the objective of finding the prevalence and risk factors associated with soil-transmitted helminth infections in school age children (5–14 years) in a rural area of Coimbatore district.

SUBJECTS AND METHODS

The study was conducted in the field practice area of the Rural Health Training Center (RHTC) Vedapatti, Coimbatore. RHTC caters to a total population of 23,841 distributed in 14 villages of Thondamuthur and Madukarai block of Coimbatore district. The total number of school-aged children (aged 5–14 years) is 3266.

Ethical clearance was obtained from Institutional Human Ethics Committee, in 2014. The sample size was calculated to be 819 assuming 34.5% as prevalence, relative precision of 15%, design effect of 2, and nonresponse rate of 20%.[16] Five out of 14 villages were selected by the cluster sampling method. House-to-house survey was conducted in the five villages during November 2015–July 2016. All school-age children (aged 5–14 years) who were permanent residents of Vedapatti field practice area of RHTC were included in the study. Children who were not available on three visits within a week time were excluded from the study.

At the home setting, after getting consent from the parent and assent from the child any one of the parents of the child was interviewed in the evening hours of the day. A structured questionnaire was used to collect the information on demographic, socioeconomic, and environmental information such as availability of type of drinking water and availability of functioning sanitary toilet. Few questions were asked regarding the knowledge and attitude of the parents on STH. Respondent was asked to give comment on the personal hygiene practices of child such as washing hands with soap before taking food and after defecation, eating fallen foods on the floor, wearing foot wear outside the house and intake of de-worming tablets in the past 3 months. Observations were also made regarding the personal hygiene of the children related to STH such as clipped nails. Knowledge and attitude score was generated from the correct responses for the knowledge and attitude questions. The correct responses were given a score of one, and maximum score one could get was nine. Score five and above was considered as adequate knowledge and attitude score.

At the end of survey, a screw-capped plastic container with the identification of the child was given to collect the stool sample of the child on the next morning. Instructions regarding stool collection were given. The stool samples were collected and transported to microbiology laboratory within 4 h of sample collection. Stool samples were examined by saline wet mount and iodine wet mount.[17] Iodine preparation was done for the better visualization of morphological details of ova. All samples were re-examined after concentrating with WHO recommended.[18] Formalin-ether sedimentation method.[19] To reduce the human error, duplicate slides (both direct and after concentration method) were prepared from each sample and the slides were read by two different microbiologists and the opinion of chief microbiologist was considered as final.

Analysis

Data entry was made in the Microsoft Excel software in codes and analysis was done with SPSS-19 (IBM, Armonk, New York ,United States) computer package. The presence of ova of A. lumbricoides, Trichuris trichiura, N. americanus, and A. duodenale was considered as the dependent variable. The prevalence is expressed in percentage with 95% confidence interval (CI). Univariate analysis and logistic regression were performed to find the associations between the independent variables and dependent variables. Strength of association was expressed in terms of odds ratio (OR) and adjusted OR with 95% CI and P < 0.05 was considered as statistically significant.

RESULTS

The results of this study are based on 610 children, who gave one adequate stool sample. Totally, 819 children participated in the survey; hence, the nonresponse rate was calculated as 25.52.

The distribution of the study population and their risk factors is shown in Tables 1 and 2. The mean age of the study population was 8.92 ± 2.68. Among them, children below 10 years (58.5%), female participants (52.1%), belonged to families with members four and above (54.92%), children living in kutcha and semi-pucca houses( 80%), and children belonged to low socioeconomic status (52.3%) Class IV and V according to the modified Prasad classification were found in majority. Illiteracy was found among 20.2% of mothers. Open air defecation was found among 33.4% of the children. Regarding the toilet usage, only 50.7% of the children were using the toilets in the home. Around 66% did not wash their hands with soap before taking food. Moreover, 44.6% did not wash their hands with soap after defecation. Around 63% children regularly used foot wear and around 70% of the children had trimmed nail during the visit. Nearly half of the parents of children had adequate knowledge on STH. Only 59% reported intake of de-worming tablets in the past 3 months.

Table 1

Association of soil transmitted helminthiasis with socioeconomic and demographic factors by univariate and multivariate analysis

Factors	Category	STH		OR (95% CI)		P
		Yes	No	Unadjusted	Adjusted
Age	≥10	24	229	1.52 (0.80-2.90)	1.45 (0.78-2.7)	0.24
	<10	23	334	1	1
Sex	Male	24	268	1.15 (0.60-2.18)	1.07 (0.58-2.00)	0.82
	Female	23	295	1	1
Total number of family members	Less than 4	22	253	1.08 (0.56- 2.05)	1.21 (0.64- 2.27)	0.55
	Four and above	25	310	1
Type of house	Pucca house	4	115	0.36 (0.09-1.03)	0.34 (0.10- 0.91)	0.05
	Others (Semipucca, Kutcha House)	43	448	1	1
Mother’s educational status	Illiterate	10	113	1.08 (0.46-2.29)	1.03 (0.43- 2.30)	0.94
	Literate	37	450	1	1
SES (modified Prasad Scale)	Lower SES (Class IV,V)	26	293	1.14 (0.60-2.19)	1.10 (0.56-2.20)	0.78
	High SES (Class I,II,III)	21	270	1	1

STH: Soil transmitted helminthiasis, OR: Odds ratio, CI: Confidence interval, SES: Socioeconomic status

Table 2

Association of soil transmitted helminthiasis with risk factors by univariate and multivariate analysis

Factors	Category	STH		OR (95% CI)		P
		Yes	No	Unadjusted	Adjusted
Open air defecation	Yes	16	188	1.03 (0.51-2.00)	1.10 (0.56-2.20)	0.68
	No	31	375	1	1
Type of safe drinking water	Pipe water	36	427	1.04 (0.50-2.33)	0.93 (0.45-2.06)	0.86
	Others (UV/RO/boiled water)	11	136	1	1
Habit of eating unwashed vegetables	Yes	13	168	0.90 (0.42-1.80)	0.82 (0.38-1.72)	0.61
	No	34	395	1	1
Habit of Eating foods fallen on ground	Yes	1	21	0.56 (0.01-3.66)	0.62 (0.03-3.30)	0.65
	No	46	542	1	1
Washing with soap before eating	No	27	313	1.08 (0.57-2.08)	0.89 (0.40-1.93)	0.76
	Yes	20	250	1	1
Washing with soap after toilet	No	24	248	1.32 (0.70-2.52)	1.57 ( 0.71-3.51)	0.27
	Yes	23	315	1	1
Regular foot wear usage	No	16	207	0.89 (0.44-1.72)	0.92 (0.46-1.79)	0.81
	Yes	31	356	1	1
Nail clipping	No	11	175	0.68 (0.30-1.40)	0.63 (0.28- 1.34)	0.25
	Yes	36	388	1	1
Deworming during past 3 months	No	22	228	1.29 (0.68-2.45)	1.43 (0.76-2.66)	0.26
	Yes	25	335	1	1
Knowledge attitude score regarding STH	Inadequate	25	296	1.02 (0.54-1.96)	0.90 (0.47 -1.72)	0.75
	Adequate	22	267	1	1

STH: Soil transmitted helminthiasis, RO: Reverse osmosis, UV: Ultraviolet, OR: Odds ratio, CI: Confidence interval

The prevalence of STH among 610 children who had given one adequate stool sample and whose parents participated in survey was 7.70% (95% CI: 5.58–9.82). Among all STH, A. lumbricoides was highly prevalent 6.9% (95% CI: 4.89%–8.91%) followed by Hook worm 0.7% (0.04%–1.36%), and Trichuris trichura 0.2% (0.15%–0.55%).

There was no significant association found between STH and factors influencing STH by univariate analysis. However, when all independent variables were subjected to multivariate logistic regression analysis, only pucca houses offered protection OR: 0.34(95% CI: [0.10–0.91]) against STH.

DISCUSSION

Relatively high nonresponse rate (25.52%) was noted in this study. It is also evident from a similar study by Shubha and Fatima[20] that surveys involving bio samples shows high nonresponse rate (30.9%) when compared to simple questionnaire-based surveys.

The prevalence of STH in the study population is 7.7% (95% CI 5.58–9.82%). The results of the current study were less than other studies conducted in the nearby areas.

The explanations for the low prevalence are more number of risk group (29.13%) were found among the nonresponders compared to younger children (22.72%, P = 0.02). The study results were based on single stool sample, modified formol-ether concentration (FEC) method with low sensitivity (63.1%)[21] which could have estimated the low prevalence. The other probable explanations are Mass Drug Administration (MDA) under NDD[15] might have changed the scenario.[56789] However, there are no sufficient data from to compare prevalence before de-worming in this area to support this statement. Coimbatore first round of NDD was just completed and second round was on-going at the time of the survey (2016-Feb). Kattula et al.[8] also explains the reason for the low prevalence of STH (7.8%) in Vellore area is due to Albendazole supplied in MDA along with diethylcarbamazine since 2004. Deworming using albendazole rapidly declines the overall prevalence of STH, and this is evident from Mani et al.[22] study on efficacy of albendazole in Tamil Nadu. However, there are other studies reported with a higher prevalence in the nearby areas. Kaliappan et al.[23] explains the reason for the increased prevalence (39%) in Thiruvanamalai District in the year 2013 could be due to five stool samples collected among tribal population where open-air defecation and bare foot walking were common practice. Ragunathan et al.[16] explains the reason for higher prevalence (34.56%) reported in Pudhucherry, a coastal area using FEC method in year 2006 is due to poor hygienic practices of the participants.

This study showed the most common soil-transmitted helminth as A. lumbricoides with the prevalence of 6.9% (95% CI: 4.89%–8.91%) followed by Hook worm 0.7% (95% CI: 0.04%–1.36%) and T. trichura 0.2% (95% CI: 0.15%–0.55%). In general studies showed that A. lumbricoides and T. trichura were more common among urban children and hookworm infestation among rural children.[24]

Regarding the factors influencing STH pucca houses offered protection OR: 0.34(95% CI: [0.10–0.91]) against STH, by multivariate analysis. A cross-sectional study by Kattula et al.[8]. showed that children living in Hut/Kutcha houses are at higher risk for STH.

Kattula et al.[8] also showed that children of more than 10 years of age, living in households without toilet, open air defecation, unhygienic practices like keeping untrimmed nails are important risk factors for STH. Kattula et al.[8] showed that the consumption of deworming tablets offered protection. However, there was no significant association noted in this study. This is a cross-sectional study; hence, the cause-effect relationship cannot be determined and is the major limitation of this study. Moreover, the other limitations are as follows: the study results were based on single stool sample which could have estimated the low prevalence. The newer techniques with higher sensitivity would have given higher prevalence. Sample size was not adequate to comment on factors influencing STH.

CONCLUSION

The prevalence of STH in a rural area of Coimbatore is 7.7% (95% CI: 5.58–9.82), and is continuing as a public health problem. Open-air defecation is a biggest concern (33.4%); hence, more private, public toilets should be built in this area. The children should be trained to use toilet facilities either private or public. It is very important to raise the awareness about these infections; hence, parents of children with inadequate knowledge should be given health education. When regular deworming is accompanied by appropriate sanitation and hygiene activities designed to prevent reinfection, a long-term impact can be achieved.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.