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Foci of Schistosoma mansoni in Assiut province in Middle Egypt
404 TRANSACIIONS or THE ROYALSOCIETY OF TROPICALMEDICINE AND HYGIENE (1993) 87, 404-405
Foci of Schistosoma
mansoni
in Assiut province
in Middle
Egypt
Ahmed Medhat’, Mahmoud A. Abdel-Aty2, Mohamed Nafeh’, Hammam Hammam2, Abdella Abdel-Samia3 and G. Thomas Strickland4 Departments of ‘Tropical Medicine, 2Epidemiology and Preventive Medicine and 3Parasitology, Assiut University Faculty of Medicine; 41nternational Health Program and Department of Epidemiology and Preventive Medicine, University of Maryland School of Medicine, Baltimore, Maryland, USA Abstract Following detection of Schistosma mansoni in a 12 years old boy who had both schistosomal polyposis and periportal fibrosis with hepatosplenomegaly, epidemiological studies to confirm local transmission were performed in his and 30 other villages in Assiut Governorate, Egypt. The index case’s brother and 6 of 380 inhabitants of his village who provided stool specimens were infected with S. mansoni and a farmer with dysentery and hepatosplenomegaly had a positive rectal snip biopsy. All had hepatic abnormalities on ultrasound examination. Two of 221 schoolchildren in another village had mixed infections with S. mansoni and S. haematobium; 17 others had only S. haematobium. None of 419 inhabitants living near the infected boys had S. mansoni infection. Snails from canals and drains near both villages were netted, identified, counted and checked for infection: in the second village one of 1039 Bulinus truncatus was infected with Schistosoma sp. but none of 859 Biomphalaria alexandrina was infected. Schistosomiasis mansoni is being focally transmitted in 2 villages in Assiut Governorate and appears to be spreading from Lower to Middle and Upper Egypt. We believe B. alexandrina, which has been present in some of the waterways for at least 15 years, were infected recently by local inhabitants returning from Iraq or by cattle traders or military recruits from the Delta. Introduction During the past 15 years it has become apparent that major changes are evolving in the epidemiological pattern of schistosomiasis in the Nile valley of Egypt followinn construction of the Aswan High Dam (EL ALAMY et al, 1977; ABDEL-WAHAB et al.,-1979; A~DEL-WAHAB 1982: CLINE et al.. 1989). Biomnhalaria alexandrina snails have been noted focally in’ Assiut Governorate since 1976. Recently, reductions in BulinuslBiomphalaria ratios were reported in areas where both genera have been detected (MEDHAT et al., 1989). Reported herein are Schistosoma mansoni infections in children living in 2 villages in Assiut Governorate in Eavnt who had not beenexposed to infection away from %eir communities. This documents S. mansoni transmission in Middle Egypt, an area where S. haematobium had been thought to be the only indigenous Schistosoma species. Case histories A 12 years old boy from El Hamam village seen in the out-patient clinic at Assiut complained of rectal bleeding and easily becoming fatigued of 2 months duration. His general physical examination was normal except for marked pallor. He had an enlarged liver (right lobe measured 18 cm in the midclavicular line [MCL] and left lobe had a span of 13 cm in the midline [ML]). The liver was firm in consistency but not tender. His spleen was palpated 3 cm below the left costal margin. Urinalysis was normal and Schistosoma ova were not seen microscooicallv in the urine. However, S. mansoni ova were present in the faeces. He had microcytic hypochromic anaemia with a haemoglobin of 9.2 g/dL and erythrocyte count of 3.72~ 109/L. Liver function tests were normal. Abdominal ultrasonography demonstrated hepatic enlargement (20 cm snan in MCL. 14 cm soan in ML), a co&se bright echogenic pattern of the live; with grade11 periportal thickening, and splenic enlargement to 3 cm below the costal margin. The portal vein was not dilated and the gall bladder, kidneys, ureters and urinary bladder were normal. Many sessile oolvns, 2-3 cm in length, were seen in the rectum and sign&l colon duringsigmoidoscoov. These were friable and bled easilv. Rectal snip biopsy showed numerous living and dead S: mansoni ova, confirming a pathological diagnosis of schistosomal polyposis. Address far correspondence: Dr G. T. Strickland, International Health Proeram. Universitv of Marvland School of Medicine, Baltimore, &ID 21201, USA. ’ Address for offprint requests: Schistosomiasis Research Project, Medical Services Corporation International, 1716 Wilson Boulevard, Arlington, VA 22209, USA. This article is not copyright.
The patient received one 40 mgikg dose of praziquantel and oral iron supplementation before discharge from the hospital. One month later he still complained of rectal bleeding, although it was reduced. No ovum was present in his stool. However, he was treated again with praziquantel and the iron supplementation was continued. One month later, he still complained of persistent rectal bleeding and sigmoidoscopy showed the rectal polyps to be marginally smaller. No living S. mansoni ovum was detected by rectal snip biopsy. Surgical consultation was advised but the familv refused an oneration. While the boy was in hospital, his mother reported that his 10 vears old brother also had rectal bleeding. This child’s stool contained blood, mucus and S. manso% ova. However, colonic polyps were not detected by sigmoidoscopy and rectal snip biopsies did not detect S. mansoni ova. Neither he nor his brother had ever had potential exposure to schistosomal cercariae away from El Hamam. Epidemiological studies Unon verification of S. mansoni infection in the 2 bovs. who-had not been exposed to infection away from their villaee. the Assiut Governorate Ministrv of Health was con&ted and permission was obtained to investigate the prevalence and source of schistosomiasis mansoni in the community. El Hamam A team from the Assiut University Faculty of Medicine went to El Hamam, the village, 10 km north-east of Assiut city, where the brothers resided. Methods. A population sample was selected from households in the vicinitv of the brothers’ home and from children attending 2 primary schools in the village. Urine specimens were collected, allowed to sediment in a flask, and examined under low magnification for schistosome ova. A faecal smear in saline of the stool was also examined under low magnification for ova. Abdominal ultrasound examinations-were performed on those with S. mansoni infection, using a oortable Schimasonic SDL 32@machine with a linearphased transducer of 3.5 MHz frequency. The methods used in the ultrasound examination have been described by NAFEH et al. (1992). Results. Of 920 urine samples examined, 75 (8.2%) contained ova of S. haematobium. Six (1.6%) \ , of the 380 stool samples from villagers contained ova of S. mansoni. Four of these had both S. mansoni in the stool and S. haematobium in the urine. Ultrasound examination of the
405 6 persons with schistosomiasis mansoni demonstrated hepatic enlargement in all 6, splenomegaly in 3, and grade I periportal fibrosis in 2. Another subject, a 31 years old farmer with negative urine and stool ova examinations, was found to have living S. mansoni ova by rectal snip biopsy. Sigmoidoscopy was performed because he had dysentery and hepatosplenomegaly and had recently returned from Iraq. B. alexandrina snails were collected from the local waterways and examined, but none was found to be infected with Schistosoma. Bani Magd Cluster sample surveys were performed in 30 villages in Assiut Governorate to search for any other S. mansoni foci. A total of 4200 inhabitants had urine and stool examinations for Schistosoma ova. S. mansoni was detected in only one village, Bani Magd, 23 km north of Assiut. Seventeen (7.7%) of 221 schoolchildren had S. haematobium, while 2 hah mixed infections with S. haematobium and S. mansoni. The village was mapped and divided into sectors. Stools and urines were then collected from 419 subjects living in households near to those of the 2 children with schistosomiasis mansoni, from friends who swam with them in the canal, from farmers recently returned from Iraq, and from villagers who had recently worked or served in the military forces in Lower Egypt where S. mansoni is endemic. Ninetytwo (22.0%) were positive for S. haematobium, but no further case of S. mansoni was detected. Snails were netted from the canals and drains near this village. They were identified, sorted and examined for infection. One of 1039 B. truncatus was found to be infected with Schistosoma. None of 859 B. alexandrina netted near the village was infected. Discussion
Schistosomiasis mansoni is present in at least 2 villages in Assiut Governorate. In the Nile Delta it has replaced S. haematobium as the predominant species (EL ALAMY & CLINE, 1977; ABDEL-WAHAB et al., 1979; ABDELWAHAB, -1982; CLINE et al., 1989). Recently; autochthonous transmission has been confirmed south of Cairo: in Minya, between Cairo and Assiut on the river Nile (ORIEBY et al., 1988), and in the Fayoum, a large oasis in the eastern end of the western desert between Cairo and Minya (ABDEL-WAHAB et al., in press). In addition, Ministry of Health reports during ihe 1980s noted sporadic cases of S. mansoni in Middle and Upper Egypt and Schistosoma eggs with lateral spines have been detected in the urine of schoolchildren in villages in Beni Suef Governorate since 1982. Although no zetai or reference was given, a statement was published that ‘limited autochthonous transmission of S. mansoni’ is occurring in Middle and Upper Egypt, including ‘an outbreak at Al Sharbi Bahjoura in Qena Governorate in 1984 and early 1985’ (WILLMOTT, 1987). We believe schistosomiasis mansoni will continue spreading up the Nile river as B. alexandrina replaces B. truncatus in the canals and drains (MEDHAT et ai.,1989). Focal increases of distribution and abundance of the snail intermediate host for S. mansoni in Middle and Upper Egypt have been reported by the Ministry of Health and in academic theses followine construction of the Aswan High Dam in the 1960s. Wevdemonstrated an abundance of Biomphaluria in both villages, but did not
detect any infected snails. The Bulinus infection rate was low (0.1%) in Beni Magd, even thouah 17.3% of the inhabiiants examined in tlhis village had-S. haematobium infections. The orobable source of infection for Biom6haluria in El Hamam was a farmer who had recently re;urned from Iraq. Cattle traders from the Delta who pass through most Assiut villa es from time to time, and military recruits returning Brom endemic areas, are other poiential infectious s&rces for local snails. Workers from the Delta emnloved in building schools are suspected of having iniected Biomphala& in the Fayoum (ABDEL-WAHAB et al., in press). It is interesting that the first case of schistosomiasis mansoni transmitted in Assiut presented to a clinician with 2 complications: schistosomal polyposis and hepatosplenic schistosomiasis resulting from periportal fibrosis. Either this boy had been infected for a longer period than we expected, or he had an exaggerated morbid immune response. The latter is also suggested by his apparent failure to improve following praziquantel therapy, although the period of observation was not adequate to confirm this impression. Acknowledgements Dr Ibrahim Faraq, formerly of the Ministry of Health in Assiut Governorate, provided information and access to the villages. Drs Youssef Swifee, Hosnia Said, Ahmed Hani, and the residents in the Department of Tropical Medicine assisted in rhis work. This research was supported by the Egyptian Ministry of HealthiUsAlD funded Schistosomiasis Research Project no. 263-0140.2, grant no. 02-04-22. References Abdel-Wahab, M. F. (1982). Schistosomiasis in Egypt. Boca Raton, Florida: CRC Press. Abdel-Wahab, M. F., Strickland, G. T., El-Sahly, A., ElKady, N., Zakaria, S. & Ahmed, L. (1979). Changing pattern of schistosomiasis in Egypt 1935-75. Lancer, ii, 242-244. Abdel-Wahab, M. F., Yosery, I., Narooz, S., Esmat, G.,, El Hak. S.. Nasif. S. & Strickland. G. T. (in Dress). Is Schisr+ so& mkoni ‘replacing S. ha&atob& in tge Fayoum? AmericanJournal of Tropical Medicine and Hygiene. Cline, B. L., Richards, F. O., El Alamy, M. A., El Hak, S., Ruiz-Tiben, E., Hughes, J. M. & McNeeley, D. F. (1989). 1983 Nile Delta Schistosomiasis Survey: 48 years after Scott. AmericanJournal of Tropical Medicine and Hygiene, 41,56-62. El Alamy, M. A. & Cline, B. L. (1977). Prevalence and intensity of Schistosoma haematobium and S. mansoni infection in Qalyab, Egypt. Amen’canJournal of Tropical Medicine and Hygiene, 26,470-472. Medhai, A., Nagiub, M., Khalifa, R. & Nafeh, M. A. (1989). Species and infectivity of schistosome snails in Middle Egypt. Bulletin of the Alexandria Faculty of Medicine, 25,68%692. Nafeh, M. A., Medhat, A., Swifee, Y., Moftah, F. M., Mohamed, A., Soliman, A.-G. A. & Strickland, G. T. (1992). Ultrasonographic changes of the liver in Schistosoma haematobium infection. American Yournal of TroDical Medicine and Hvgiene, 47,225-230. 1 I . Oriebv. A. M.. Hammam. H. H.. Hamed. E. M. S.. El-Torkv. M. +A. & Zazour, A. e. (1988). Acute’schistosomiasis mahI soni in El-Minia Governorate (Upper Egypt). Egyptian Journal ofBilharziasis, 10, 137-155. Willmott, S., editor (1987). Report of an independent evaluation mission on the National Bilharzia Control Program, Egypt, 1985 (abridged version). Transactions of the Royal Society of Tropical Medicine and Hygiene, 81, supplement.
Received 24 August 1992; revised 10 May 1993; accepted for publication 11 May 1993
Foci of Schistosoma
mansoni
in Assiut province
in Middle
Egypt
Ahmed Medhat’, Mahmoud A. Abdel-Aty2, Mohamed Nafeh’, Hammam Hammam2, Abdella Abdel-Samia3 and G. Thomas Strickland4 Departments of ‘Tropical Medicine, 2Epidemiology and Preventive Medicine and 3Parasitology, Assiut University Faculty of Medicine; 41nternational Health Program and Department of Epidemiology and Preventive Medicine, University of Maryland School of Medicine, Baltimore, Maryland, USA Abstract Following detection of Schistosma mansoni in a 12 years old boy who had both schistosomal polyposis and periportal fibrosis with hepatosplenomegaly, epidemiological studies to confirm local transmission were performed in his and 30 other villages in Assiut Governorate, Egypt. The index case’s brother and 6 of 380 inhabitants of his village who provided stool specimens were infected with S. mansoni and a farmer with dysentery and hepatosplenomegaly had a positive rectal snip biopsy. All had hepatic abnormalities on ultrasound examination. Two of 221 schoolchildren in another village had mixed infections with S. mansoni and S. haematobium; 17 others had only S. haematobium. None of 419 inhabitants living near the infected boys had S. mansoni infection. Snails from canals and drains near both villages were netted, identified, counted and checked for infection: in the second village one of 1039 Bulinus truncatus was infected with Schistosoma sp. but none of 859 Biomphalaria alexandrina was infected. Schistosomiasis mansoni is being focally transmitted in 2 villages in Assiut Governorate and appears to be spreading from Lower to Middle and Upper Egypt. We believe B. alexandrina, which has been present in some of the waterways for at least 15 years, were infected recently by local inhabitants returning from Iraq or by cattle traders or military recruits from the Delta. Introduction During the past 15 years it has become apparent that major changes are evolving in the epidemiological pattern of schistosomiasis in the Nile valley of Egypt followinn construction of the Aswan High Dam (EL ALAMY et al, 1977; ABDEL-WAHAB et al.,-1979; A~DEL-WAHAB 1982: CLINE et al.. 1989). Biomnhalaria alexandrina snails have been noted focally in’ Assiut Governorate since 1976. Recently, reductions in BulinuslBiomphalaria ratios were reported in areas where both genera have been detected (MEDHAT et al., 1989). Reported herein are Schistosoma mansoni infections in children living in 2 villages in Assiut Governorate in Eavnt who had not beenexposed to infection away from %eir communities. This documents S. mansoni transmission in Middle Egypt, an area where S. haematobium had been thought to be the only indigenous Schistosoma species. Case histories A 12 years old boy from El Hamam village seen in the out-patient clinic at Assiut complained of rectal bleeding and easily becoming fatigued of 2 months duration. His general physical examination was normal except for marked pallor. He had an enlarged liver (right lobe measured 18 cm in the midclavicular line [MCL] and left lobe had a span of 13 cm in the midline [ML]). The liver was firm in consistency but not tender. His spleen was palpated 3 cm below the left costal margin. Urinalysis was normal and Schistosoma ova were not seen microscooicallv in the urine. However, S. mansoni ova were present in the faeces. He had microcytic hypochromic anaemia with a haemoglobin of 9.2 g/dL and erythrocyte count of 3.72~ 109/L. Liver function tests were normal. Abdominal ultrasonography demonstrated hepatic enlargement (20 cm snan in MCL. 14 cm soan in ML), a co&se bright echogenic pattern of the live; with grade11 periportal thickening, and splenic enlargement to 3 cm below the costal margin. The portal vein was not dilated and the gall bladder, kidneys, ureters and urinary bladder were normal. Many sessile oolvns, 2-3 cm in length, were seen in the rectum and sign&l colon duringsigmoidoscoov. These were friable and bled easilv. Rectal snip biopsy showed numerous living and dead S: mansoni ova, confirming a pathological diagnosis of schistosomal polyposis. Address far correspondence: Dr G. T. Strickland, International Health Proeram. Universitv of Marvland School of Medicine, Baltimore, &ID 21201, USA. ’ Address for offprint requests: Schistosomiasis Research Project, Medical Services Corporation International, 1716 Wilson Boulevard, Arlington, VA 22209, USA. This article is not copyright.
The patient received one 40 mgikg dose of praziquantel and oral iron supplementation before discharge from the hospital. One month later he still complained of rectal bleeding, although it was reduced. No ovum was present in his stool. However, he was treated again with praziquantel and the iron supplementation was continued. One month later, he still complained of persistent rectal bleeding and sigmoidoscopy showed the rectal polyps to be marginally smaller. No living S. mansoni ovum was detected by rectal snip biopsy. Surgical consultation was advised but the familv refused an oneration. While the boy was in hospital, his mother reported that his 10 vears old brother also had rectal bleeding. This child’s stool contained blood, mucus and S. manso% ova. However, colonic polyps were not detected by sigmoidoscopy and rectal snip biopsies did not detect S. mansoni ova. Neither he nor his brother had ever had potential exposure to schistosomal cercariae away from El Hamam. Epidemiological studies Unon verification of S. mansoni infection in the 2 bovs. who-had not been exposed to infection away from their villaee. the Assiut Governorate Ministrv of Health was con&ted and permission was obtained to investigate the prevalence and source of schistosomiasis mansoni in the community. El Hamam A team from the Assiut University Faculty of Medicine went to El Hamam, the village, 10 km north-east of Assiut city, where the brothers resided. Methods. A population sample was selected from households in the vicinitv of the brothers’ home and from children attending 2 primary schools in the village. Urine specimens were collected, allowed to sediment in a flask, and examined under low magnification for schistosome ova. A faecal smear in saline of the stool was also examined under low magnification for ova. Abdominal ultrasound examinations-were performed on those with S. mansoni infection, using a oortable Schimasonic SDL 32@machine with a linearphased transducer of 3.5 MHz frequency. The methods used in the ultrasound examination have been described by NAFEH et al. (1992). Results. Of 920 urine samples examined, 75 (8.2%) contained ova of S. haematobium. Six (1.6%) \ , of the 380 stool samples from villagers contained ova of S. mansoni. Four of these had both S. mansoni in the stool and S. haematobium in the urine. Ultrasound examination of the
405 6 persons with schistosomiasis mansoni demonstrated hepatic enlargement in all 6, splenomegaly in 3, and grade I periportal fibrosis in 2. Another subject, a 31 years old farmer with negative urine and stool ova examinations, was found to have living S. mansoni ova by rectal snip biopsy. Sigmoidoscopy was performed because he had dysentery and hepatosplenomegaly and had recently returned from Iraq. B. alexandrina snails were collected from the local waterways and examined, but none was found to be infected with Schistosoma. Bani Magd Cluster sample surveys were performed in 30 villages in Assiut Governorate to search for any other S. mansoni foci. A total of 4200 inhabitants had urine and stool examinations for Schistosoma ova. S. mansoni was detected in only one village, Bani Magd, 23 km north of Assiut. Seventeen (7.7%) of 221 schoolchildren had S. haematobium, while 2 hah mixed infections with S. haematobium and S. mansoni. The village was mapped and divided into sectors. Stools and urines were then collected from 419 subjects living in households near to those of the 2 children with schistosomiasis mansoni, from friends who swam with them in the canal, from farmers recently returned from Iraq, and from villagers who had recently worked or served in the military forces in Lower Egypt where S. mansoni is endemic. Ninetytwo (22.0%) were positive for S. haematobium, but no further case of S. mansoni was detected. Snails were netted from the canals and drains near this village. They were identified, sorted and examined for infection. One of 1039 B. truncatus was found to be infected with Schistosoma. None of 859 B. alexandrina netted near the village was infected. Discussion
Schistosomiasis mansoni is present in at least 2 villages in Assiut Governorate. In the Nile Delta it has replaced S. haematobium as the predominant species (EL ALAMY & CLINE, 1977; ABDEL-WAHAB et al., 1979; ABDELWAHAB, -1982; CLINE et al., 1989). Recently; autochthonous transmission has been confirmed south of Cairo: in Minya, between Cairo and Assiut on the river Nile (ORIEBY et al., 1988), and in the Fayoum, a large oasis in the eastern end of the western desert between Cairo and Minya (ABDEL-WAHAB et al., in press). In addition, Ministry of Health reports during ihe 1980s noted sporadic cases of S. mansoni in Middle and Upper Egypt and Schistosoma eggs with lateral spines have been detected in the urine of schoolchildren in villages in Beni Suef Governorate since 1982. Although no zetai or reference was given, a statement was published that ‘limited autochthonous transmission of S. mansoni’ is occurring in Middle and Upper Egypt, including ‘an outbreak at Al Sharbi Bahjoura in Qena Governorate in 1984 and early 1985’ (WILLMOTT, 1987). We believe schistosomiasis mansoni will continue spreading up the Nile river as B. alexandrina replaces B. truncatus in the canals and drains (MEDHAT et ai.,1989). Focal increases of distribution and abundance of the snail intermediate host for S. mansoni in Middle and Upper Egypt have been reported by the Ministry of Health and in academic theses followine construction of the Aswan High Dam in the 1960s. Wevdemonstrated an abundance of Biomphaluria in both villages, but did not
detect any infected snails. The Bulinus infection rate was low (0.1%) in Beni Magd, even thouah 17.3% of the inhabiiants examined in tlhis village had-S. haematobium infections. The orobable source of infection for Biom6haluria in El Hamam was a farmer who had recently re;urned from Iraq. Cattle traders from the Delta who pass through most Assiut villa es from time to time, and military recruits returning Brom endemic areas, are other poiential infectious s&rces for local snails. Workers from the Delta emnloved in building schools are suspected of having iniected Biomphala& in the Fayoum (ABDEL-WAHAB et al., in press). It is interesting that the first case of schistosomiasis mansoni transmitted in Assiut presented to a clinician with 2 complications: schistosomal polyposis and hepatosplenic schistosomiasis resulting from periportal fibrosis. Either this boy had been infected for a longer period than we expected, or he had an exaggerated morbid immune response. The latter is also suggested by his apparent failure to improve following praziquantel therapy, although the period of observation was not adequate to confirm this impression. Acknowledgements Dr Ibrahim Faraq, formerly of the Ministry of Health in Assiut Governorate, provided information and access to the villages. Drs Youssef Swifee, Hosnia Said, Ahmed Hani, and the residents in the Department of Tropical Medicine assisted in rhis work. This research was supported by the Egyptian Ministry of HealthiUsAlD funded Schistosomiasis Research Project no. 263-0140.2, grant no. 02-04-22. References Abdel-Wahab, M. F. (1982). Schistosomiasis in Egypt. Boca Raton, Florida: CRC Press. Abdel-Wahab, M. F., Strickland, G. T., El-Sahly, A., ElKady, N., Zakaria, S. & Ahmed, L. (1979). Changing pattern of schistosomiasis in Egypt 1935-75. Lancer, ii, 242-244. Abdel-Wahab, M. F., Yosery, I., Narooz, S., Esmat, G.,, El Hak. S.. Nasif. S. & Strickland. G. T. (in Dress). Is Schisr+ so& mkoni ‘replacing S. ha&atob& in tge Fayoum? AmericanJournal of Tropical Medicine and Hygiene. Cline, B. L., Richards, F. O., El Alamy, M. A., El Hak, S., Ruiz-Tiben, E., Hughes, J. M. & McNeeley, D. F. (1989). 1983 Nile Delta Schistosomiasis Survey: 48 years after Scott. AmericanJournal of Tropical Medicine and Hygiene, 41,56-62. El Alamy, M. A. & Cline, B. L. (1977). Prevalence and intensity of Schistosoma haematobium and S. mansoni infection in Qalyab, Egypt. Amen’canJournal of Tropical Medicine and Hygiene, 26,470-472. Medhai, A., Nagiub, M., Khalifa, R. & Nafeh, M. A. (1989). Species and infectivity of schistosome snails in Middle Egypt. Bulletin of the Alexandria Faculty of Medicine, 25,68%692. Nafeh, M. A., Medhat, A., Swifee, Y., Moftah, F. M., Mohamed, A., Soliman, A.-G. A. & Strickland, G. T. (1992). Ultrasonographic changes of the liver in Schistosoma haematobium infection. American Yournal of TroDical Medicine and Hvgiene, 47,225-230. 1 I . Oriebv. A. M.. Hammam. H. H.. Hamed. E. M. S.. El-Torkv. M. +A. & Zazour, A. e. (1988). Acute’schistosomiasis mahI soni in El-Minia Governorate (Upper Egypt). Egyptian Journal ofBilharziasis, 10, 137-155. Willmott, S., editor (1987). Report of an independent evaluation mission on the National Bilharzia Control Program, Egypt, 1985 (abridged version). Transactions of the Royal Society of Tropical Medicine and Hygiene, 81, supplement.
Received 24 August 1992; revised 10 May 1993; accepted for publication 11 May 1993