The Epidemiology of Schistosomiasis in Egypt: Minya Governorate
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Am. J. Trop. Med. Hyg., 62(2)S, 2000, pp. 65–72 Copyright ᭧ 2000 by The American Society of Tropical Medicine and Hygiene THE EPIDEMIOLOGY OF SCHISTOSOMIASIS IN EGYPT: MINYA GOVERNORATE NABIL S. GABR, TAREK A. HAMMAD, ANWAR ORIEBY, EGLAL SHAWKY, MAHMOUD A. KHATTAB, AND G. THOMAS STRICKLAND Departments of Medical Parasitology and Internal Medicine, Minya University School of Medicine, Minya, Egypt; Department of Epidemiology and Preventive Medicine, School of Medicine, University of Maryland at Baltimore, Maryland Abstract. Risk factors, prevalence, and intensity of infection with Schistosoma sp. and prevalence and magnitude of morbidity caused by schistosomiasis was assessed in a stratified random sample of 16,433 subjects from 2,409 households in 33 rural communities in Minya Governorate, Egypt. The prevalence of S. haematobium ranged from 1.9% to 32.7% among the communities and averaged 8.9%. The average intensity of infection was a geometric mean egg count (GMEC) of 8.5 per 10 ml of urine and ranged from 1.6 to 30.9. Prevalence was maximum (18–20%) in those 10–20 years of age and higher in males than in females. Intensity of infection followed the same pattern. Infection with S. mansoni was present almost exclusively in a single village, confirming spread of this species up the Nile River and its focality in Minya. Risk factors for S. haematobium infection were an age from 11 to 20; male gender; males bathing in, women washing clothing or utensils in, and children swimming or playing in canals; and a history of, or treatment for, schistosomiasis. Recent history of burning micturition was associated with infection in children but not in adults, while a history of blood in urine correlated with S. haematobium infection in both age groups. Reagent strip-detected hematuria and proteinuria were highly associated, particularly in children, with S. haematobium infection. The presence of hepatomegaly or splenomegaly on physical examination was not associated with S. haematobium ova in the urine. Hepatomegaly, as measured by ultrasonography in the midclavicular line or the midsternal line, or ultrasonography-detected splenomegaly were not present more frequently in infected subjects than in uninfected subjects. Schistosoma ova were not detected more frequently in urine of subjects with ultrasonog- raphy-detected periportal fibrosis than in the urine from subjects without this finding. Ultrasonography-detected uri- nary bladder wall lesions were detected in only 6 (0.3%) subjects and obstructive uropathy was observed in 54 (2.7%) subjects. The absence of an association between prevalence of urinary tract morbidity and S. haematobium infections was surprising. Two possible explanations are 1) that repeated chemotherapy has reduced the prevalence of urinary tract morbidity and 2) that morbidity was not being detected by the ultrasonographic operators. Minya is 1 of the 3 Governorates that constitute Middle household levels but the whole household was included in Egypt. It is about 240 km south of Cairo between Beni-Suef the study sample. and Assiut on the Nile River. It is bounded on the east by The interview technique for collecting vital, environmen- the Nile River and on the west by the western desert. There tal, sociodemographic, and medical data is described in de- are three main carrier canals, in addition to the Nile River tail.1 Quantitative microscopic counting of Schistosoma ova that supply Minya with water. The total area of Minya is was performed in stool (using a modified Kato technique) 2,262 km2 and the population density is 1,292 persons/km2. from 11,688 subjects and in urine (using the Nuclepore The total population according to the 1986 census of the [Pleasanton, CA] filter technique) from 12,134 individuals Central Agency for Population Mobilization and Statistics as described.2 was 3,075,691, of whom 75% lived in rural areas. Physical examination and abdominal ultrasonography A population-based study, the Epidemiology 1, 2, 3 Pro- were performed by trained physicians upon inhabitants of ject, sponsored by the Egyptian Ministry of Health/United every fifth household as described.3 Although the protocol States Agency for International Development (USAID)- called for excluding children less than 5 years old, many sponsored Schistosomiasis Research Project, performed were examined and the data from those evaluated are in- cross-sectional surveys in 9 Governorates in Egypt in 1991 cluded; 2,208 inhabitants from 479 households had clinical and 1992. The objectives were to assess 1) the prevalence and ultrasound investigations, the results of which were re- and intensity of infection with Schistosoma sp., 2) the prev- corded on 2 additional forms. alence and magnitude of morbidity caused by schistosomi- Not all data from the 2,208 subjects having physical and asis, and 3) the changing pattern of schistosomiasis in Egypt. ultrasonographic examinations were available for complete Herein, we report the results of this survey in Minya Gov- analysis for the following reasons: 1) 233 (10.6%) did not ernorate. provide urine specimens for parasitology, hematuria, and proteinuria examinations; 2) 327 (14.8%) did not provide SUBJECTS AND METHODS stool specimens for parasitology examination; 3) 1,404 (63.6%) did not have height and weight measured and re- The sample size, selected by multistage random sampling, corded; 4) 31 (1.4%) did not respond to the question re- was calculated to detect a prevalence of Schistosoma sp. as garding a history of schistosomiasis; 5) 29 (1.3%) did not low as 5% in each ezba (satellite communities) or mother respond to the question regarding prior treatment for schis- village with a 90% confidence level. The findings are con- tosomiasis; 6) 136 (6.2%) failed to respond to the question sidered representative of the rural areas of the entire gov- regarding burning micturition; and 7) 115 (5.2%) did not ernorate.1 The total sample population consisted of 16,433 answer the question regarding blood in the urine. individuals from 2,409 households in 8 villages and their The most important among these omissions are 1) the ab- ezbas. Randomization took place at the village/ezba and sence of urine specimens from 10% of the subjects, which 65 66 GABR AND OTHERS TABLE 1 Odds ratio and 95% confidence limits for risk factors for infection with Schistosoma haematobium in Minya Governorate* Infected Risk factor Total in group No. (%) Odds ratio Confidence limits Demographics Age groups (years) 0–10 4,015 357 (8.9) 11–20 2,775 493 (17.8) 2.21 1.91–2.56 21–35 2,506 152 (6.1) 0.66 0.54–0.81 36–55 1,891 51 (2.7) 0.28 0.21–0.38 Ͼ55 947 32 (3.4) 0.36 0.25–0.52 Gender Female 6,182 365 (5.9) Male 5,952 720 (12.1) 2.19 1.92–2.50 Domicile Village (Ն500 houses) 4,053 401 (9.9) Ezba (Ͻ500 houses) 8,081 684 (8.5) 0.84 0.74–0.96 Exposure to canal water Bathing (males) No 4,667 510 (10.9) Yes 1,150 196 (17.0) 1.67 1.40–2.00 Washing (females) No 4,633 247 (5.3) Yes 1,536 118 (7.7) 1.48 1.18–1.85 Playing (children Ͻ15 years old) No 4,752 513 (10.8) Yes 479 97 (20.3) 2.10 1.65–2.67 Clinical findings History of schistosomiasis No 8,698 749 (8.6) Yes 1,633 210 (12.9) 1.57 1.33–1.84 Prior treatment of schistosomiasis No 9,759 827 (8.5) Yes 1,637 210 (12.8) 1.59 1.35–1.87 History of burning micturition No 1,298 108 (8.3) Yes (total) 641 66 (10.3) 1.26 0.92–1.75 Ͻ15 years 180 32 (17.8) 1.62 1.02–2.58 Ն15 years 461 34 (7.4) 1.26 0.79–1.99 History of blood in urine No 1,622 125 (7.7) Yes 339 50 (14.7) 2.07 1.46–2.94 Ͻ15 years 127 26 (20.5) 1.94 1.18–3.19 Ն15 years 212 24 (11.3) 2.23 1.35–3.68 Hepatomegaly in MCL (by PE) No 565 49 (8.7) Yes 164 10 (6.1) 0.68 0.34–1.38 Ͻ15 years 71 7 (9.9) 0.88 0.35–2.16 Ն15 years 93 3 (3.2) 0.41 0.12–1.39 Splenomegaly (by PE) No 1,829 167 (9.1) Yes 129 8 (6.2) 0.66 0.32–1.37 Ͻ15 years 19 4 (21.1) 1.76 0.57–5.41 Ն15 years 110 4 (3.6) 0.53 0.19–1.47 Laboratory findings Hematuria No 9,433 426 (4.5) Yes 2,477 648 (26.2) 7.49 6.56–8.55 Ͻ15 years 915 382 (41.7) 12.64 10.48–15.25 Ն15 years 1,562 266 (17.0) 5.17 4.26–6.27 SCHISTOSOMIASIS IN EGYPT 67 TABLE 1 Continued Infected Risk factor Total in group No. (%) Odds ratio Confidence limits Proteinuria No 11,429 889 (7.8) Yes 478 185 (38.7) 6.49 6.15–9.11 Ͻ15 years 217 133 (61.3) 14.83 11.11–19.80 Ն15 years 261 52 (19.9) 3.66 2.66–5.05 Ultrasonography Hepatomegaly in MCL No 565 48 (8.5) Yes 165 12 (7.3) 0.84 0.44–1.63 Ͻ15 years 73 10 (13.7) 1.41 0.62–3.22 Ն15 years 92 2 (2.2) 0.26 0.06–1.13 Hepatomegaly in MSL No 697 58 (8.3) Yes 32 2 (6.3) 0.73 0.17–3.15 Ͻ15 years 13 1 (7.7) 0.65 0.08–5.21 Ն15 years 19 1 (5.3) 0.77 0.10–5.94 Splenomegaly No 1,675 151 (9.0) Yes 267 17 (6.4) 0.69 0.41–1.15 Ͻ15 years 56 5 (8.9) 0.64 0.25–1.65 Ն15 years 211 12 (5.7) 0.89 0.47–1.68 Periportal fibrosis No 1,689 150 (8.9) Yes (Ն3 mm) 266 24 (9.0) 1.02 0.65–1.60 Ͻ15 years 56 9 (16.1) 1.26 0.60–2.66 Ն15 years 210 15 (7.1) 1.17 0.65–2.10 Grade I (3–Ͻ5 mm) 262 22 (8.4) 0.94 0.59–1.50 Grade II (5–Ͻ7 mm) 2 2 (100.0) Grade III (Ն7 mm) 2 0 (0.0) Bladder wall lesions No 1,969 174 (8.8) Yes 6 1 (16.7) 2.06 0.24–17.76 Ͻ15 years 3 1 (33.3) 3.28 0.29–36.55 Ն15 years 3 0 (0.0) Obstructive uropathy No 1,964 174 (8.9) Yes 54 3 (5.6) 0.61 0.19–1.96 Ͻ15 years 5 0 (0.0) Ն15 years 49 3 (6.1) 0.88 0.27–2.85 * MCL ϭ midclavicular line; PE ϭ physical examination; MSL ϭ midsternal line.