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Human blood samples and indoor-resting Culex pipiens were collected in 33 randomly selected houses from different sectors of a village in the Nile Delta of Egypt which was endemic for Wuchereria bancrofti. Blood was also collected from subjects with no history of living in filarial endemic areas. Human blood samples were divided and assessed by both membrane filtration and polymerase chain reaction (PCR). Similarly, mosquito samples were assessed by both dissection and PCR. Blood pools representing each household were tested by PCR. If a pool gave a positive result, then individual blood specimens were also tested by PCR. Of the 33 houses tested, both membrane filtration and blood pools assayed by PCR identified 14 (42.4%) 'infected houses'. PCR detected parasite deoxyribonucleic acid (DNA) in blood pools from an additional 3 households that gave negative results by membrane filtration. Of 178 endemic blood samples tested by membrane filtration, 22 (12.3%) had microfilariae and all were individually positive by PCR. Although microfilaria counts were lower in blood collected during the day than in night-collected blood, the PCR results were consistent, regardless of time of collection. All non-endemic blood samples were negative by PCR. Among the 33 houses rested, mosquito pools assayed by PCR identified 17 (51.5%) as 'infected households'. Of these, 8 houses (47%) contained at least one microfilaraemic resident. One 'infected household' was identified by mosquito dissection. We concluded that PCR is a powerful epidemiological tool for screening villages for the prevalence of W. bancrofti. PCR detection of W. bancrofti DNA in blood-fed mosquitoes could be used initially to locate endemic areas with transmission of bancroftian filariasis. PCR detection of W. bancrofti DNA in blood collected during the day could then be used to assess W. bancrofti infection rates.

Abstract. Residents of Egypt's Nile river delta have among the world's highest seroprevalence of hepatitis C virus (HCV) infection. To assess the impact of HCV on chronic liver disease, we studied the association between HCV, other hepatitis viruses, and cirrhotic liver disease in a cross-sectional, community-based survey of 801 persons aged Ն 10 years living in a semi-urban, Nile delta village. Residents were systematically sampled using questionnaires, physical examination, abdominal ultrasonography and serologically for antibodies to HCV (confirmed by a thirdgeneration immunoblot assay) and to hepatitis A virus (HAV), hepatitis B virus (HBV), and hepatitis E virus (HEV). The seroprevalence of HCV increased with age from 19% in persons 10-19 years old to about 60% in persons 30 years and older. Although no practices that might facilitate HCV transmission were discovered, the seroprevalence of HCV was significantly associated with remote (Ͼ 1 year) histories of schistosomiasis. Sonographic evidence of cirrhosis was present in 3% (95% CI: 1%, 4%) of the population (0.7% of persons under 30 years of age and in 5% of older persons), and was significantly associated with HCV seroreactivity. Our findings are consistent with the hypothesis that past mass parenteral chemotherapy campaigns for schistosomiasis facilitated HCV transmission, and that HCV may be a major cause of the high prevalence of liver cirrhosis in this Nile village.

Abstract. We initiated a longitudinal study of Bancroftian filariasis to improve understanding of dynamics and risk factors for infection in villages near Cairo, Egypt. Baseline prevalence rates for microfilaremia and filarial antigenemia for 1,853 subjects more than 9 years of age were 7.7% and 11.2%, respectively. Microfilaria counts, antigen levels, and microfilaremia incidence over a 1-year period were all significantly lower in older people. These findings suggest that humans develop partial immunity to Wuchereria bancrofti over time. One-year incidence rates for microfilaremia and antigenemia were 1.8% and 3.1%, respectively. Filarial antigenemia, IgG4 antibody to recombinant antigen BmM14, and household infection were all significant risk factors for microfilaremia incidence. Microfilaria counts and parasite antigen levels were significantly reduced by diethylcarbamazine therapy, but many infected subjects refused treatment, and most treated people were still infected one year later. Incident infections approximately balanced infections lost to produce an apparent state of dynamic equilibrium.

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