Anaemia and Intestinal Parasitic Infections Among School Age Children in Behera Governorate, Egypt

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1 Anaemia and Intestinal Parasitic Infections Among School Age Children in Behera Governorate, Egypt by F. Curtate,* M. Nabil,** A. El Wakeel,** M. Y. Shamy,*** and the Behera Survey Team *Directorate General for Development Cooperation, Italian Embassy, Cairo, Egypt **Ministry of Health, Behera Regional Office, Damanhour, Egypt ***High Institute of Public Health, University of Alexandria, Alexandria, Egypt Summary Anaemia is considered a serious public health problem hi Egypt, although updated population-based data are lacking. Similarly, data on prevalence and intensity of infection with intestinal parasites, which are considered one possible cause of anaemia, are available only from small, unrepresentative sample surveys. The present research was implemented on an entire Governorate representative sample. The aim of the study was to assess the prevalence of anaemia and Intestinal parasites hi the area and to evaluate the role of each parasite in the epidemiology of anaemia among school age children. At the end of the survey, results of faecal analyses from direct smear and the Kato-Katz examination techniques were available from 1844 and 1783 children respectively, as well as haemoglobin levels measured by spectrophotometer from 1238 children aged 6-12 years. The prevalence of anaemia hi the area was high (90 per cent), but very few serve forms were detected (< 2 per cent). Prevalence of Intestinal parasites was high only for protozoa (Giardia inttstinalis 24.7 per cent Entamoeba histolytica 17.5 per cent) and Schistosoma mansoni (20.7 per cent). From analysis of the results, Fasciola infection appeared to be highly endemic, even among children (3 per cent), and emerged as the factor most strongly correlated with low levels of haemoglobin (p < ). The effect of Fasciola on haemoglobin levels was related to the intensity of Infection with this parasite. The role of S. mansoni as a risk factor for anaemia was supported by the present study. Among the protozoa, G. intestinalis was significantly correlated with low haemoglobin levels (p < 0.05). The present results substantiated similar findings from smaller studies. In future research, the relationship between Fasciola infection and anaemia needs to be studied with a well-controlled longitudinal design. Introduction Q Anaemia is a global health concern, because of its negative effects on physical development, intellectual performance, work capacity, and pregnancy. 1 It is the most common disorder in the world, as it is in the Eastern Mediterranean Region (EMR) where more than 140 Acknowledgements The present study was implemented in the framework of the bilateral cooperation project, 'Strengthening Rural Health Services in Behera, Dakhalija and Quena Governorates' (AID No 3703), between the Rural Health Unit of the Ministry of Health, Egypt, and the Directorate General for Development Cooperation, Ministry of Foreign Affairs, Italy. The Schistosoma and Intestinal Parasites programmes of the World Health Organization, Geneva, provided laboratory materials, training aids, and the technical advice needed for conducting the faecal analyses. The authors are indebted to Drs L. Savioli and A. Montresor, WHO/Geneva; Professor Orecchia and Dr Di Cave, University of Rome 'Tor Vergata', for their useful suggestions on the manuscript. Correspondence: Dr Filippo Curtale, Italian Cooperation do Italian Embassy, 1079 Corniche El Nil, Garden City, Cairo, Egypt Fax million people, mostly children, are estimated to be anaemic according to WHO criteria. 2 The most common cause of anaemia is nutritional deficiency of iron and/or folate. hi the EMR the overall supply of iron per capita is higher than in other regions, but the diet consists of a high consumption of vegetables, which are low in the bioavailability of iron. The bioavailability of ingested iron is further reduced by high consumption of foods rich in iron absorption-inhibiting factors, such as tea (tannin) and unleavened bread (phytate). 2 Intestinal parasitic infection is another possible cause of anaemia, especially for children, who usually present a higher intensity and prevalence of infection than adults. 3 ' Haemoglobinopathies and other inherited disorders also contribute to the high prevalence of anaemia, especially in the Mediterranean region, but their importance remains unclear. 2 In Egypt, anaemia is considered to be a moderate to severe problem, but national data are limited and outdated. The last national survey, conducted in 1978, identified high prevalence among preschool children and women. 5 Small size surveys of school children revealed that anaemia is also a major nutritional problem among this age group. 6 The Country paper submitted to the Journal of Tropical Pediatrics Vol.44 December 1998 Oxford University Press

2 F. CURT ALE ET AL. International Conference on Nutrition (FAO, Rome 1992), estimated the prevalence of anaemia among preschool children in Egypt to be between 75 and 90 per cent, but data on school age children were not presented. Similarly, national and regional data on the prevalence and intensity of infection with intestinal parasites are limited. Protozoa, especially Giardia intestinalis and Entamoeloa histolytica, are considered highly endemic, while intestinal helminths, with the exception of Schistosoma, are not considered a serious health problem in the country. 8 During 1996, a study was implemented in the Govemorate of Behera, where the highest prevalence of anaemia had been reported in The survey targeted school age children, who are considered a priority group for intervention. 9 ' 10 The aim of the study was to collect population-based data on the prevalence of anaemia and intestinal parasites and, at the same time, evaluate the effect of infection with intestinal parasites, both protozoa and helminths, and the haemoglobin status of children in the area. Materials and Methods The study consisted of a household survey carried out from October to December 1996 in Behera, Lower Egypt. This Govemorate covers a wide territory on the Western side of the Delta, from the Nile river to the Eastern desert, with an estimated population of more than 4 million. Sampling The sample size was calculated for 770 households, divided in 55 clusters of 14 households according to the protocol advocated by WHO.'' The method adopted for sample selection was a two-stage random cluster sampling technique with probability of inclusion proportionate to size (PPS) in the first stage. 12 The study design effect, to adjust for cluster selection compared to a full random selection, was calculated to equal 2. For all the children living in the selected households, information was collected by coded questionnaire together with a faecal specimen from children 6 months to 12 years of age and a blood sample from school age children (6-12 years old). Faecal analysis Within 1 h of collection, two slides were prepared and coded for each sample. The first was a direct smear preparation to be read immediately. The second was a Kato Katz thick-smear preparation to be read after 24 h. The direct smear (iodine wet-mount preparation) was intended for diagnosis of protozoa such as C. intestinalis and E. histolytica. This technique is less accurate than the faecal concentration technique, but easier to implement in field conditions and is considered appropriate for screening in large sample populations, diagnosis was made on the identification of cysts. 13 The Kato-Katz technique was used for quantitative diagnosis of intestinal helminths. 14 The egg count for the side was converted to 'eggs per grams of faeces' (e.p.g.) by a multiplication factor of 24, taking into account that a template of 41.7 mg was used. Hookworms were not reported in the area, thus only one reading of the slides was made after 24 h of preparation to detect all other species of helminths, and again after 1 week for internal quality control. No attempt was made to differentiate between Fasciola hepatica and Fasciola gigantica. Both will be referred to as Fasciola. Blood analysis Haemoglobin determination was performed by the cyanmethaemoglobin method using a spectrophotometer as recommended by WHO. 15 Samples of capillary blood from the fingertip of each child were collected after discarding the first drop. Whole blood was diluted with Drabkins solution immediately after collection and read in the field laboratory within 6 h of being diluted. Statistical analysis Differences in haemoglobin levels were calculated by /-test for the protozoa, for which only data on prevalence were available. Associations between helminths and a low level of haemoglobin were tested by calculating the correlation coefficient after the individual egg counts had been converted to logarithms using the n + 1 transformation. 3 Finally, to assess the relative contribution of each parasite and confounding factors in the changes in haemoglobin status, all the variables associated significantly with lower levels of haemoglobin were included in a multiple regression model against haemoglobin as the dependent variable. 17 The data were analysed statistically by microcomputer using SPSS for Windows (version 6.0). Results General prevalence On completion of the field work, haemoglobin determinations were available from 1238 children. The mean level of haemoglobin among school age children in the study area was 10.47g/dl (SD = 1.18). About 90 per cent of the children examined were below the WHO cutoff point indicative of anaemia in a school age population living at sea level (Hb < 12g/dl). However, only two subjects (< 0.2 per cent) appeared to be affected by severe anaemia (Hb < 7 g/dl). From the results of the 1844 direct smears and 1783 Kato-Katz preparations, protozoa appeared to be more prevalent than helminths. Cysts of G. intestinalis and E. histolytica were present in 24.7 and 17.5 per cent of the screened children, respectively. The overall prevalence for helminths (and mean e.p.g. for infected children) is presented in Table 1. Prevalence and intensity of infection by age group for the different parasites were consistent with the recent literature. 1 Infection with Hymenolepis nana presented peak intensity in the age group 3 4 years, which had not been observed before, while intensity of infection with 324 Journal of Tropical Pediatrics Vol.44 December 1998

3 F. CURT ALE ET AL TABLE 1 Prevalence and intensity of infection (e.p.g.) with intestinal helminths among 1783 children, aged 6 months to 12 years, in Behera by Kato-Katz thick-smear technique, Egypt, 1996 Species n Prevalence (%) Mean e.p.g." Min-max e.p.g. S. mansoni H. nana A. lumbricoides T. trichiura Fasciola H. hetervphyes Negative Kato-Katz test Single infections Multiple infections "Infected children only Fasciola showed a moderate but constant increase with age (Fig. 1). Bivariate analyses Paired blood and stool results were available from 1066 children by direct smear and 1035 children by Kato- Katz technique. Of the two protozoal infections detected, only giardiasis appeared to be associated with a significant difference in haemoglobin levels (mean difference -0.17; t = 2.03; p = 0.04) as measured by a two-tailed (-test. For intestinal helminths, the presence of single or multiple infection, as detected by positive Kato-Katz test, was associated with significantly lower levels of haemoglobin. Considering each parasite, the most significant negative correlation with haemoglobin level was that of Fasciola, followed by 5. mansoni and T. trichiura (Table 2). As expected, age correlated positively with haemoglobin levels (r = 0.06, p = 0.02). The two soil-transmitted helminths, A. lumbricoides and T. trichiura, appeared to be correlated to one another at a very significant level (r = 0.23, p = 0.000). A less significant correlation emerged between S. mansoni and Fasciola (r = 0.07, p = 0.002). FIG. 1. Relationship between age group and intensity of infection with H. nana (n = 137) and Fasciola (n = 54) among children below 12 years of age in Behera (Egypt, 1996) Multiple regression As a last step in the statistical analyses, multiple regression was performed which included all the children for whom results from blood, direct smear, and Kato-Katz analyses were available (total n = 995). The stepwise multiple regression equation, with haemoglobin levels as the dependent variable, showed that the intensity of infection with Fasciola, expressed as the logarithm of the individual e.p.g. after the n + 1 transformation, was the most important determinant of low haemoglobin levels, followed by S. mansoni and G. intestinalis (Table 3). The effect of Fasciola infection on haemoglobin levels appeared to be related to the worm load, indirectly measured as the mean e.p.g. for a group of individuals (Fig. 2). Discussion From the analysis of the survey results, the study population appeared to be significantly anaemic, although not severely anaemic. At the same time, the overall prevalence of infection with intestinal parasites was moderate and in some cases low, even if areas with high intensity of infection were detected. The prevalence of protozoal infection raises concern, especially taking into account that, with a more sensitive technique, the actual prevalence might have been above 50 per cent. Fascioliasis was confirmed to be an emerging infectious disease in the area, highly endemic among children. The prevalence detected (3 per cent) was consistent with the results reported by a recent study implemented among school children in another Govemorate of the Delta region (5.1 per cent). 19 In the same study, the sensitivity of the Kato-Katz technique for diagnosis of fascioliasis was calculated to be 47 per cent of that of the ELIS A test, thus the actual prevalence in Behera, for school children, might be above 6 per cent. Among the helminths, 5. mansoni showed the highest prevalence. This result was unexpected, taking into account the enormous efforts undertaken in Egypt to control schistosomiasis. Although the prevalence of intestinal parasites in the Journal of Tropical Pediatrics Vol.44 December

4 F. CURTALE ET AL. TABLE 2 Relationship between blood haemoglobin levels and infection with intestinal helminths, diagnosed by positive Kato-Katz thick-smear examination technique, among 1035 school age children in Behera, Egypt, 1996 Species n Haemoglobin (g/dl) MeaniSD Difference r P S. mansoni H. nana A. lumbricoides T. trichiura Fasciola H. hetcrophycs Negative Kato-Katz test Single infections Multiple infections ± ± ± ± ± ± ± ± ± ± ± ± The correlation coefficient (r) was calculated after converting the individual egg count by the log (n + 1) transformation. One-way analysis of variance (ANOVA) for single and multiple infection. area was not very high, the presence of most of them appeared to be significantly related to low levels of haemoglobin. S. mansoni and T. trichiura are known to cause blood loss in the stool, thus they are well recognized risk factors for anaemia. 3 Also, G. intestinalis infection is known adversely to affect haemoglobin status, probably through impaired absorption of vitamin B, 2 and folate. 20 Giardiasis was associated with anaemia in one community study. 21 Mild to moderate anaemia has been described in cases of animal and human fascioliasis, especially in severe infections; this may result from blood loss through bile duct lesions typical of this parasite. In Egypt, fascioliasis was recently associated with iron deficiency anaemia in a group of hospitalized patients with chronic infection. 23 In general, most publications on this subject are based on single case studies or small series of hospitalized patients. No reports from community-based or epidemiological surveys are available. Multiple regression analysis confirmed Fasciola egg TABLE 3 Multiple regression analysis of factors influencing blood haemoglobin level among 995 school age children in Behera, Egypt, 1996, with blood haemoglobin level (g/dl) as dependent variable. Independent variables Fasciola S. mansoni Age (months) G. imestinalis Constant Variables not included in T. trichiura Beta the equation B SEoffl T P Helminths expressed as log (n + I) of the individual number of eggs per gram of faeces, G. inxestinalis as presence/absence of cysts in direct smear, age in months. Method: Stepwise. F = ; Sign F = ; R 2 = Journal of Tropical Pediatrics Vol.44 December 1998

5 F. CURTALE ET AL. 12 T (996) 11" 9 i % v Intensity of Fasciola infection (cp.g.) FIG. 2. Relationship between mean haemoglobin levels (± 1 SD) and intensity of Fasciola infection, indirectly measured as mean egg count for group of cases. (N) indicates the number of cases in each group. Significance tested by one-way analysis of variance (ANOVA): F = 5.87, p < Total n = Egypt, count as the most important determinant of low haemoglobin levels, among all the independent variables studied, followed by S. mansoni egg count and G. inttstinalis infection. Although data on the intensity of infection for giardiasis were not available, the technique used for diagnosis (direct smear) examined only a small amount of faecal material, thus the positive cases must be considered highly infected and the association with anaemia may be present only with a high intensity of infection. The exclusion of T. trichiura from the equation was probably due to the low prevalence of this parasite in the study area. In general the prevalence of intestinal parasites was low compared with the high prevalence of anaemia in the area, and the independent variables included in the equation explained just 5 per cent of the overall variability in haemoglobin levels (R 2 = 0.053). This reminds us that other factors, among those mentioned in the introduction, were concurrent causes for the high prevalence of anaemia in the region. The position taken by Fasciola in the multiple regression, considering its relatively low prevalence among the study population, seems to indicate an important role of this parasite in the epidemiology of anaemia. However, solid evidence for a causal relationship between helminth infection and anaemia can only be obtained by the statistically supported demonstration of two phenomena. 3 First, the severity of anaemia should increase with increasing worm burden. This has been demonstrated clearly for Fasciola by the present study (Fig. 2), taking into account that the mean egg count for a group of individuals can be considered representative of mean worm burden. 1 Second, in an infected group of individuals, haemoglobin level should rise after treatment more than in a non-infected or placebo group, which can only be demonstrated in a longitudinal treatment-control study. In conclusion, this study showed the importance of intestinal parasitic infections as determinants of anaemia in the region in combination with other possible risk factors. The association of 5. mansoni and G. intestinalis infections with anaemia in school children was confirmed by the present findings. Among all the intestinal parasites detected, Fasciola emerged as the most important determinant of anaemia in the area. The effect of Fasciola on haemoglobin levels needs further study of a well-controlled, longitudinal design. References DeMaeyer EM, et al. Preventing and Controlling Iron Deficiency Anaemia Through Primary Health Care. WHO, Geneva, Verster A, Van der Pols JC. Anaemia in the Eastern Mediterranean Region. Eastern Mediterranean Health Journal. 1995; 1: Stephenson LS. The Impact of Helminth Infection on Human Nutrition. Taylor & Francis Ltd, London, Journal of Tropical Pediatrics Vol.44 December

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