Chemotherapy-based control of schistosomiasis haematobia. II. Metrifonate vs. praziquantel in control of infection-associated morbidity

To determine the relative efficacy of metrifonate and praziquantel in controlling urinary tract morbidity due to Schistosoma haematobium infection, a random allocation treatment trial was performed among 1,813 school age S. haematobium-infected children from the Msambweni area of Coast Province, Kenya. Following baseline examination for infection, hematuria, proteinuria, and ultrasonographic urinary tract abnormalities, oral treatment with either metrifonate (10 mg/kg, repeated at 4 month intervals) or praziquantel (1 dose of 40 mg/kg) was given to infected subjects. Prevalence of morbidity was reassessed 12 months later for each treatment group. Results indicated equivalent patient improvement in response to either regimen: prevalence of hematuria fell from 75% to 17% after either praziquantel or metrifonate therapy. Similarly, prevalence of proteinuria was significantly reduced from 73% to 29% (metrifonate) or 27% (praziquantel) after therapy. Metrifonate and praziquantel caused similar reductions in bladder granulomata and bladder thickening; however, no reduction in hydronephrosis was noted with either drug. Analysis of outcomes in population subgroups defined by age, sex, pretreatment intensity of infection, or severity of pretreatment morbidity showed no consistent advantage for either drug. In this endemic area, both agents provide effective control of morbidity due to urinary schistosomiasis.     

Chemotherapy-based control of schistosomiasis haematobia. IV. Impact of repeated annual chemotherapy on prevalence and intensity of Schistosoma haematobium infection in an endemic area of Kenya

To determine the effect of repeated, annual, age-targeted therapy on prevalence and intensity of Schistosoma haematobium infection in an endemic area, we treated all available, infected, school-age children (n = 2, 493) in the Msambweni area of Coast Province, Kenya with a randomized protocol of oral metrifonate (10 mg/kg for three doses each year) or praziquantel therapy (40 mg/kg as a single dose each year) for a period of one to three years. During 1984-1987, 1, 101 children completed three years of therapy, 550 received two years, and 842 received a single year. Annual followup revealed significant long-term suppression of S. haematobium infection in the targeted school-age population. Both cross-sectional analysis and study of individual outcomes suggested maximal suppression of infection after two years of therapy. Suppression lasted more than two years after cessation of treatment, and was associated with reduced community transmission (gauged by decreased prevalence among new study entrants and decreasing negative-to-positive conversion on annual parasitologic examinations). Comparison of metrifonate and praziquantel outcomes indicated greater suppression of infection and longer infection-free intervals for some subgroups given praziquantel. We conclude that annual population-based therapy targeted to schoolchildren has direct and indirect beneficial effects for endemic communities. In some specific situations, repeat therapy may not suppress transmission, and reduced drug efficacy may be observed after one to three years, suggesting the need for additional non-drug control measures in highly endemic villages.     

吡喹酮化疗在血吸虫病防治中的作用

本文阐述了吡喹酮化疗在控制传染源和血吸虫病防治中的作用,同时提出了值得思考和关注的问题。     

Urinary tract morbidity in schistosomiasis haematobia: associations with age and intensity of infection in an endemic area of Coast Province, Kenya

To gain better understanding of the natural history of Schistosoma haematobium associated disease, age- and intensity-related urinary tract morbidity were assessed in a cross-sectional study of Kilole (population 719) in Coast Province, Kenya. Overall prevalence of infection was 65% (39% light, 16% moderate, 9% heavy). Infection prevalence and mean intensity of infection were highest in the 5-14-year-old bracket for both sexes. Although significant intensity-associated increases in hematuria prevalence were noted for both children and adults in all infection categories, hematuria was more common in those less than 15 years of age. Children had a significant increase in the prevalence of dysuria at higher levels of infection, whereas adults did not. Radiographic study of a 1:9 random sample, stratified for age, revealed a greater prevalence of urinary tract granulomas in those less than 15 years. Subjects greater than 15 years of age had a greater frequency of hydronephrosis. Hydronephrosis, hydroureter, and bladder calcification were not associated with higher infection intensity. Among individuals with bladder calcification, a potential marker of cumulative inflammation, 87% had hydronephrosis or hydroureter, compared to a 40% prevalence among individuals without bladder calcification. These findings suggest that certain structural forms of urinary tract disease, such as hydronephrosis, progress during the course of untreated schistosomiasis haematobia despite age-related reductions in egg burden, whereas other forms of morbidity, such as hematuria, remain sensitive to the level of urinary egg excretion at the time of diagnosis.     

Reduction in prevalence, intensity of infection and morbidity due to Schistosoma mansoni infection in a community following treatment with praziquantel

Five hundred and twenty-three individuals from an area endemic for Schistosoma mansoni infection were followed for a 16 month period in a population-based study in rural Zambia. Those found infected in each of five surveys were treated with praziquantel (40 mg kg-1 body weight). Data on prevalence, intensity of infection and morbidity (intestinal symptoms and liver and spleen enlargements) were also gathered. At the end of the study, prevalence had fallen from 64.8% to 11.5%, intensity of infection had dropped from 28.2 to 0.5 eggs per gram of stool (geometric means) and morbidity showed marked reduction.     

Discrepancies in outcome of a control program for schistosomiasis haematobia in Fayoum governorate, Egypt

A large scale mollusciciding and chemotherapy program in the Fayoum area of Egypt was reported to have decreased prevalence of schistosomiasis haematobia from 46% to 7% in approximately 12 years. In order to assess the uniformity of results reported, we have studied the prevalence and intensity of urinary tract disease in a random sample of children aged 6 months-12 years in 3 areas selected on the basis of distance from the main canal supplying Fayoum and where mollusciciding was applied. Only 1 location near the main canal showed low prevalence (2.2%), while in the other 2 areas prevalence was 75.3% and 61.3%. Intensity of infection and disease were significantly more in the latter 2 locations. Following chemotherapy, a marked reduction in prevalence and intensity of infection and reversal of pathology was seen. Since the reported favorable results of the Fayoum project were used to implement a wider control program in southern Egypt, an independent assessment must be included in future plans.     

血吸虫病肝纤维化与感染度关系分析

感染度是反映人体虫负荷数量的指标，它和血吸虫病肝纤维化的关系，近年来的报告不太一致［１，２］。我们以克粪虫卵数（ＥＰＧ）和循环抗原（ＣＡｇ）反应强度表示感染度，分析其与血吸虫病肝纤维化的关系，结果如下。１对象和方法①对象四川省眉山县正山口乡白埝、马营...     

桐城市1例输入性埃及血吸虫病的调查分析

目的分析1例国外输入性血吸虫病的诊疗过程和流行病学调查结果,为提高输入性埃及血吸虫病防治能力提供参考。方法收集患者的临床诊断和治疗资料,采集患者粪便、尿液进行实验室检测,并开展流行病学调查。结果患者寄生虫专项检测显示血吸虫抗体阳性,粪便和尿液中未发现血吸虫虫卵,病理组织切片显示嗜酸性肉芽肿,考虑寄生虫感染。综合患者的临床症状、流行病学史及吡喹酮60 mg/kg 2日疗法治疗后好转等特点,诊断为输入性埃及血吸虫病临床诊断病例。结论输入性埃及血吸虫病易误诊,今后应加强医务人员防治知识培训。     

1例输入性埃及血吸虫病的诊治

1例埃及血吸虫病诊治过程表明, 应加强医患双方的宣教工作, 减少疾病的漏诊、 误诊; 日本血吸虫病血清免疫学 诊断方法有助于埃及血吸虫病的诊断和疗效考核; 吡喹酮治疗有效, 但在合理使用上需积累更多的病例进行总结。     

Comparative trial of oltipraz versus praziquantel in the treatment of urinary schistosomiasis in the Gabon

The efficacy of oltipraz as a schistosomicidal drug was investigated in Gabonese children suffering from urinary schistosomiasis in the dosages of 1 X 25 mg/kg body weight, 1 X 35 mg/kg body weight, and 2 X 20 mg/kg body weight and compared to praziquantel, 2 X 30 mg/kg body weight. The study was undertaken in 165 patients, and follow-up investigations were carried out 6 weeks and 12 weeks after treatment. Oltipraz showed less efficacy compared to praziquantel when dosages of 1 X 25 and 1 X 35 mg/kg body weight were given. However, oltipraz 2 X 20 mg/kg body weight was equivalent to praziquantel 2 X 30 mg/kg body weight. Parasitological cure was obtained in 79% of patients treated by oltipraz and 81% of patients treated by praziquantel. Side effects were insignificant in both treatment groups. Thus, the same parasitological cure could be achieved by oltipraz as well as by praziquantel, but with a lower dosage of oltipraz.     

Antibody responses in schistosomiasis haematobium in Somalia. Relation to age and infection intensity

Antibody responses in schistosomiasis haematobium were studied in relation to age and infection intensity in Somalia. The area is highly endemic for Schistosoma haematobium but free of S. mansoni. Antibodies of the IgG class against particulate antigens of S. mansoni adult worms were investigated by immunofluorescence (gut and somatic associated antigens) and against soluble egg and adult worm antigens by ELISA. Total IgE levels were examined by Pharmacia IgE RIA, and specific IgE against soluble adult worm antigen by enzyme immunoassay. The IgG antibody response showed a characteristic pattern with highest reactivity against both gut associated and soluble egg antigens in the age group 10-14 years, when both prevalence and intensity of the infection were highest. Reactivity against somatic associated antigen was also high in this age group, but it increased slightly and remained at high level in the older ages. It is thought that such antigen is exposed mainly after the death of the parasite and that the antigenic stimulation may remain throughout most of the life of infected individuals. On the other hand, the IgG antibody reactivity against soluble adult worm antigen was low during childhood, but it increased significantly with age. It is suggested that repeated booster effects are needed for more potent response against these antigenic components. The finding of high levels of total IgE already in the youngest age groups, together with low specific IgE response, indicates that mainly other antigens are involved in the IgE production. The specific IgE response against soluble adult worm antigen was low but increased significantly with age.     

如何看待血吸虫病的传染源控制

当前血吸虫病疫区正在实施以传染源控制为主的综合防治策略, 本文通过对血吸虫病的传染源及其控制措施作一浅析, 认为应加强血吸虫病的传染源调查, 强化感染性钉螺作为传染源控制的意义。     

铜陵县江滩地区血吸虫病疫情分析及对策

安徽省铜陵县位于长江中下游南岸,沿线长55.5 km。至2000年底,沿江有8乡镇49村流行血吸虫病,人口12.7万,耕牛4 107头,全县有螺面积3 117.08万 m~2,其中江洲滩2 389.21万m~2,占76.7％。现对1996～2000年江滩地区血吸虫病疫情资料分析如下。     

云南省血吸虫病流行现状及防控策略探讨

目的 分析云南省血吸虫病流行现状,为制订下一步防治策略提供依据。 方法 收集2014年云南省血吸虫病疫情资料,分类统计传播控制和传播阻断地区血吸虫病流行情况。 结果 目前云南省达到传播控制和阻断标准的血吸虫病流行县分别为7个和11个,其中传播阻断地区5年以上查不到螺的地区有5个。传播控制地区流行村数、人口数、耕牛数和有螺面积,分别占全省流行地区的80.94%、83.72%、79.32%和82.00%,血吸虫病传染源尚未彻底消除。 结论 云南省血吸虫病传播控制地区应继续清除残留的传染源,防止疫情回升;传播阻断地区应防止传染源输入,进一步巩固防治成果。     

Relationship of prevalence and intensity of infection to morbidity in schistosomiasis japonica: a study of three communities in Leyte, Philippines

To determine whether prevalence and intensity of infection are factors in morbidity in schistosomiasis japonica, a cross-sectional study was undertaken in three villages in Leyte, Philippines, namely, Santol (A), Santa Rosa (B), and Macanip (C). Kato thick-smear fecal examination and egg counts were made on 289 of 341 residents in Village A (85%), 824 of 1,008 in Village B (82%), and 1,113 of 1,241 in Village C (90%). Prevalences of 26%, 39%, and 44%, respectively, were found in the three villages, the majority of their populations (56-74%) remaining uninfected. Most of the infected persons (17-30% of the total population) had light infections (10-100 eggs/g feces). Moderately infected persons (101-400 eggs/g) comprised a smaller segment (7-14%), while a very small proportion (2-7%) had heavy infections (greater than or equal to 401 eggs/g). Age prevalence and egg excretion peaked earlier in the areas with higher prevalence (B and C) than in the area with the lowest prevalence (A). There was no relationship between area prevalence and mean egg count. Symptoms of inability to work, weakness, abdominal pain, and diarrhea correlated with the presence of infection in the area with the highest prevalence (C), but not in the area with the lowest prevalence (A). Except for diarrhea, there was no relationship between symptoms and intensity of infection. Very few persons presented with hepatomegaly and/or splenomegaly (1-5%). The frequency of liver enlargement on the midsternal (measuring 3-6 cm and 6 cm or more) and midclavicular line (2-4 cm), as well as spleen enlargement (Hackett 2 or greater), correlated with the presence but not with the intensity of infection. Hepatomegaly was sex- and age-related, being most common among males and among adolescents aged 10-14 years.     

The effect of repeated targeted mass treatment on the prevalence of schistosomiasis mansoni and the intensity of infection in Machakos, Kenya

In a valley in Machakos District, Kenya, the entire population was surveyed in 1976 for the presence and number of eggs of Schistosoma mansoni in their faeces. All persons with 300 or more eggs g-1 faeces were then treated with a single dose of hycanthone, 1.5 mg kg-1 body-weight. A re-survey was carried out in 1977, followed by the treatment of all persons with 200 or more eggs g-1 faeces. After another re-survey in 1978, all persons with 100 or more eggs g-1 were treated. The final survey was carried out in 1981. It was found that the treatment of persons with a high egg output had a pronounced effect on the intensity of infection in the total population, but that, after a first considerable drop in the prevalence rate, further decreases were much smaller. Continuing moderate prevalence rates in very young children were an indication of continuing transmission.     

Human schistosomiasis in Cameroon. I. Distribution of schistosomiasis

The status of schistosomiasis in Cameroon was examined in a nationwide survey of 5th grade schoolchildren. Five hundred twelve schools were surveyed; 19,524 urine and 22,166 stool samples were examined. The 3 northern provinces, which comprised 29% of the population, had 87% of all urinary and 82% of all intestinal cases. These provinces have a low seasonal rainfall. The presence of temporary bodies of water and of molluscan intermediate hosts adapted to this environment permits intense transmission of schistosomiasis haematobium and mansoni. In the rest of the country, the distribution of Schistosoma haematobium and S. mansoni was highly focal. S. intercalatum endemic areas were restricted to the equatorial forest and were small with low prevalences and intensities.     

Seroepidemiology of schistosomiasis japonica by ELISA in the Philippines. I. Underestimation by stool examination of the prevalence of infection in school children

In a longitudinal seroepidemiological study in the Schistosoma japonicum endemic area of Leyte, the ELISA technique to determine prevalence and incidence rates in elementary school children was compared with similar determinations made by a modified quantitative stool examination (MIFC). In the area of this study, Barrio Salvador, Tanauan, Leyte, the ongoing schistosomiasis japonica control program in the Philippines is dependent on stool examination by MIFC and/or the quantitative thick smear (Kato-Katz) for measurement of prevalence and incidence. Over a 3-year period with multiple periodic examinations, infection rates were measured and the serologic technique was compared to stool examination in 598 untreated children (mostly 7-10 years of age) of Salvador Elementary School. A group of 150 school children from a non-endemic area, Milagros, Masbate, provided sera as a reference negative control. ELISA results are expressed as ELISA activity (EAc) in reference to a positive control serum pooled from parasitologically confirmed cases, dilutions of which were always included in each assay. A convenient positive-negative discrimination level was chosen based on the EAc values obtained from 170 stool-positive Salvador pupils and the 150 pupils of the non-endemic area. Using the chosen discrimination level, ELISA in this study had a sensitivity of 98% and a specificity of 96%. ELISA was significantly more sensitive than stool examination in detecting infections; only 28% of the children were stool positive on a single examination in contrast with 56% positive by ELISA. A single stool examination underestimated serologic positives by 50% while two stool examinations 4 months apart reduced the underestimate to 29%. The underestimation varied by age and sex, and showed no consistent pattern in this regard. Stool-positive children had a wide variation of egg counts with a geometric mean of 6.4 eggs/g of stool, with 52% of the stool positives excreting only 1-5 eggs/g. A high percentage of infected children have a misdiagnosis of infection by stool examination. This has, in the past, resulted in many being misclassified as noninfected. This erroneous classification has serious consequences on the measurement of prevalence and incidence, on studies of clinical manifestations of the disease, and on the evaluation of serologic techniques for diagnosis. Stool examination does not give an accurate measurement of prevalence, and therefore it cannot be relied upon for the evaluation of the current control program. It is recommended that the capability to undertake serodiagnostic tests for schistosomiasis japonica be encouraged and adopted in the Philippines for field