School-based health education for the control of soil-transmitted helminthiases in Kanchanaburi province, Thailand

Soil-transmitted helminthiases are major parasitic diseases that cause health problems world-wide. School-based health education is one of several basic interventions currently recommended by the World Health Organization for the control of these infections. A 3-year programme of health education for the control of soil-transmitted helminths (STH) has recently been completed in four primary schools in the Hauykayeng subdistrict of Thong Pha Phum district, in the Kanchanaburi province of Thailand. Overall, the percentage of the schoolchildren found infected with STH increased between the start of year 1 of the intervention (16.6%) and the end of year 2 (23.8%) but showed signs of falling by the end of year 3 (19.4%). Although none of these year-on-year changes in overall prevalence was statistically significant, some significant trends were detected when the six school grades (i.e. age-groups) were considered separately. The grade showing the highest prevalence of STH infection changed, from grade 6 (representing the oldest children investigated) at the start of year 1 (when grade-1 children were excluded from the survey) to grade 1 (representing the youngest children) at the ends of year 2 and year 3. By the end of year 3, the children in grades 5 and 6 had significantly lower prevalences of infection than the grade-1 subjects. The prevalence of STH infection in the grade-1 children was significantly higher than that in any of the older grades at the end of year 2 and significantly higher than that in grades 3-6 at the end of year 3. These results indicate that the health education had a greater impact on the children in the higher grades (who, presumably had better levels of understanding and practised better, personal, infection prevention) than on the younger children. Although school-based interventions can serve as a useful entry point for parasite control, more effort, including anthelminthic treatment, may be required among the youngest children. The activities need to be sustainable and supported by appropriate school-health policies.     

Studies on the control of hookworm and other soil-transmitted helminthiases in farmers in Zhejiang Province, China

Different periodic selective chemotherapeutic schemes were used to control hookworm and other soil-transmitted helminthiases in eight villages in five counties in Zhejiang Province, China, 1985-1988. The results showed that the prevalence rates of hookworm, ascariasis, and trichuriasis decreased from 35.0-74.4%, 47.0-.76% and 22.9-47.5% to 3.2-15.8%, 9.9-47.8%, and 3.5-31.2%, respectively, using pyrantel pamoate (10 mg/kg for 1-2 days) or albendazole (400 mg for 1-2 days, once or twice a year for 2-3 years). The eggs per gram of feces of hookworm and Trichuris trichiura also dropped markedly after control. Moreover, the mean hemoglobin levels of sampled populations increased after several treatments. The authors recommend periodic selective chemotherapy as the main method to control soil-transmitted helminthiases, especially hookworm infections.     

Gnathostoma infection in fish caught for local consumption in Nakhon Nayok Province, Thailand I. Prevalence and fish species

Between August 2000 and August 2001, 12,216 fish of 73 species were purchased from several local markets in Nakhon Nayok Province, Thailand, and examined for the presence of Gnathostoma larvae. Almost all species were fresh-water fish that had grown naturally, rather than raised commercially. Eight species were found to be infected with gnathostome larvae. The overall prevalence was 5.1% (626/12,216) and a total of 5,969 larvae was recovered. The highest rate of infection (30.1 %) was found in Monopterus albus (swamp eel). The rates in the remaining infected fish were as follows: Anabas testudineus (climbing perch) 7.7%, Channa striata (striped snake-head fish) 7.4%, Clarius macrocephalus (Gunther's walking catfish) 6.7%, Channa micropeltes (giant snake-head fish) 5.1%, Channa lucius (blotched snake-head fish) 4.0%, Clarius batrachus (Batrachian walking catfish) 1.4%, and Ompok krattensis (butter sheatfish) 0.6%. The mean number of larvae/fish was highest in swamp eels (10.0 larvae/eel), and the maximum number of 698 larvae was recovered from one eel. The body sizes of the recovered G. spinigerum advanced third-stage larvae were 2.70-5.10 mm in length (average, 3.97+/-0.50 mm) and 0.29-0.60 mm in width (average, 0.40+/-0.04 mm). The average number of cephalic hooklets of the larvae from rows 1 to 4 were 41.8+/-0.5 (range, 40-43), 43.6+/-0.6 (range, 42-45), 46.1+/-0.9 (range, 44-48) and 49.3+/-0.7 (range, 48-51), respectively.     

Strongyloides stercoralis infection and chronological changes of other soil-transmitted helminthiases in an endemic area of southern Thailand

A field survey was conducted in 4 primary schools in Nakhon Si Thammarat Province, southern Thailand. By Sasa modified Harada-Mori cultivation method, 1.8% of the schoolchildren were found to be infected with Strongyloides stercoralis, and 25.1% had hookworm infection. By Kato's thick smear method, the overall prevalence of soil-transmitted helminths was 46.8%, being Trichuris trichiura 28.5%, hookworm 18.0%, and Ascaris lumbricoides 5.7%. Fecal examination, performed by Kato's thick smear and culture method, indicated that the prevalence of hookworm infection was 26.9%. The prevalence in the present study was very much lower than many previous reports in the past decade. This may indicate the partial success of the parasite control project in Thailand by mass treatment, improving the sanitation and personal hygiene of the people in the endemic area. In light infection with Trichuris, albendazole administered at a dosage of 200 mg daily for 3 days showed a 48.7% cure rate. When mebendazole was given at 100 mg twice daily for 3 days, its effectiveness was 88.5%. A lower cure rate was obtained (70.0%) in moderate to heavy infection.     

Serological study of hantavirus in the rodent population of Nakhon Pathom and Nakhon Ratchasima Provinces Thailand

A serological survey has been carried out to detect evidence of hantavirus infection in rodents from two provinces of Thailand. This study aimed to examine virus antibody in 354 rodents trapped among 6 different villages of Nakhon Pathom Province (February-March, 1998) and in 326 rodents trapped among 14 villages of Nakhon Ratchasima Province (August-October, 1998). Seroprevalence among rodents from Nakhon Pathom Province (2.3%), was mostly find in Rattus norvegicus (3.8%) and Bandicota indica (2.6%). In Nakhon Ratchasima Province seroprevalence (4.0%) was mostly in Bandicota indica (19.1%) and Rattus exulans (3.5%).     

Silent transmission of virus during a Dengue epidemic, Nakhon Pathom Province, Thailand 2001

In the year 2001 a large dengue fever (DF)/dengue hemorrhagic fever (DHF) outbreak occurred in Nakhon Pathom Province, Thailand. Three thousand one hundred twelve cases of DHF were reported, an attack rate of 393 per 100,000 population. The Nakhon Pathom Provincial Health Office immediately carried out a control action according to WHO recommendations. Active serological surveys and viral RNA isolation were carried out to detect silent transmission of dengue virus in 329 healthy volunteers in Nakhon Pathom Province subdistricts where the dengue epidemic had the highest rate of infection of 2.5 per 1000. Eight point eight percent of these volunteers had a serum sample positive for DF/DHF virus IgM antibody. The highest prevalence occurred in the 15 to 40 year old group. In two instances viral RNA was detected by PCR and dengue serotype 3 was subsequently identified. The data support the hypothesis of subclinical infection with dengue virus. This high frequency of virus circulation combined with a high population density, urbanization and increasing breeding sites for mosquitoes, needs to be taken into account in the evaluation of viral transmission during and after epidemics. This underlines the importance of community-based control in informing people of their involvement in virus transmission and the importance of personal protection.     

A survey of metacercariae in cyprinoid fish in Nakhon Ratchasima,northeast Thailand

Metacercariae were recovered from freshwater fish taken from a stream in Lum Cha Muak, Nakhon Ratchasima Province, northeast Thailand during the year 2000. Seventy-nine cyprinoid fish comprising 3 species (52 Puntius leiacanthus, 22 Cyclocheilichthys armatus, and 5 Hampla dispar) were collected. The prevalence of infection with metacercariae was 51.9%. Only two genera of metacercariae were found: Haplochinae spp and Heterophyidae spp. Haplochinae metacercariae were found in all 3 species of fish, giving rates of infection of 95.5%, 20% and 1.9% for Puntius leiacanthus, Cyclocheilichthys armatus and Hampla dispar respectively. Heterophyidae metacercariae were found only in Puntius leiacanthus, whose infection rate was 30.77%. There were fish intected at the rate of 3.8% with unclassified metacercariae. Interestingly, no fish infected with Opisthorchis viverrini metacercariae were found, which is at odds with previous reports from Thailand in which a higher infection rate was given. This is the first report of fish infected with Haplorchinae spp in Thailand.     

The prevalence and intensity of soil-transmitted helminthiases in rural communities in southern Nigeria.

An investigation of the prevalence and intensity of soil-transmitted helminthiases was undertaken in four villages in Oyo state, Nigeria. Diagnosis was based on examination of stool samples for the presence of helminth ova in all age classes. The prevalence of Ascaris lumbriocoides ranged from 61.5-72.2%, of Trichuris trichiura from 65-74%, and of hookworm from 52.4-63% depending on the village concerned. Intensity, assessed indirectly as the mean eggs per gram of faeces (epg), varied with regard to the four villages. The mean egg count of A. lumbricoides varied from 6815-10,823 per gram, of T. trichiura from 127-246, and of hookworm from 122-267. Host age, sex and household size were found to be significant factors influencing faecal egg output, and indirect measure of the intensity of the helminth infections.     

Gnathostoma infection in fish caught for local consumption in Nakhon Nayok Province, Thailand. II. Deasonal variation in swamp eels

From August 2000 to August 2001, 1844 swamp eels (Monopterus albus) were purchased from several local markets in Nakhon Nayok Province, Thailand, and examined for the presence of Gnathostoma advanced third-stage larvae. The overall prevalence was 30.1% and the mean number of larvae/eel (infection intensity) was 10.0. The highest infection rate (44.1%) was found in August 2000 and the lowest (10.7%) in March 2001. The greatest mean number of larvae/eel (75.1) was found in August 2000, whereas the fewest (2.3) was in July 2001. It is suggested that the prevalence and intensity of infection decreased within two months after the end of the rainy season and started to rise again about two months after the next rainy season began. A total of 5,532 Gnathostoma larvae were recovered from 555 infected eels, with a maximum number of 698 larvae/eel. The highest rates of Gnathostoma infection according to eel body length and weight were 87.5% in the group 91-100 cm, and 100% in groups of 901-1100 g, respectively. There were significant correlations between eel body lengths and infection rates, body lengths and infection intensities; eel body weights were also significantly correlated with infection rates and infection intensities. It was noted that the longer/ heavier the eels were, the higher would be the infection rates and the greater the infection intensities. Tissue distributions of Gnathostoma larvae in the livers and muscles of swamp eels were as follows: 43.0% of the total number of larvae were found in the muscles and 57.0% were in the liver; 29.7, 51.7, and 18.6% were in the anterior, middle, and posterior parts, respectively; 35.1% were in the dorsal part, while 64.9% were in the ventral part; 9.0, 18.7, 7.4, 20.6, 33.1, and 11.2% were in the anterodorsal, mediodorsal, posterodorsal, anteroventral, medioventral and posteroventral parts, respectively. Of the 5,532 Gnathostoma larvae examined, 1101 (19.9%) were found to possess morphological variants or abnormal cephalic hooklets. The most common unusual feature was that there were few to numerous extra rudimentary hooklets below row 4 and between the 4 rows of hooklets (7.6%), the presence of a fifth row of hooklets (3.5%), abnormal hooklets in any of the 4 rows of hooklets (5.2%), spiral arrangement of the 4 rows of hooklets (1.8%), and larvae having only 3 rows of hooklets (0.3%).     

Prevalence and distribution of soil-transmitted helminthiases among Orang Asli children living in peripheral Selangor, Malaysia

Soil-transmitted helminthiases are a public health problem in rural communities. A cross-sectional study of the prevalence and distribution of Ascaris lumbricoides, Trichuris trichiura and hookworm was conducted in 281 Orang Asli children (aborigines) aged between 2 and 15 years, from 8 Orang Asli villages in Selangor, Malaysia. All the children were infected with soil-transmitted helminthes, with 26.3% of the children infected either with A. lumbricoides, T. trichiura or hookworm and 72.6% having mixed infection. The overall prevalences of A. lumbricoides, T. trichiura and hookworm were 61.9, 98.2 and 37.0%, respectively. Approximately 19.0, 26.0 and 3.0% of the children had severe infection of ascariasis, trichuriasis and hookworm infection, respectively. The prevalences and mean egg per gram (epg) counts for A. lumbricoides and T. trichiura were not significantly dependent on age, therefore age-dependent convexity was not seen in this study. However, the results of this study reveal an age-dependent prevalence and mean epg count in children with hookworm infection. We conclude that ascariasis, trichuriasis and hookworm infection are still prevalent and therefore a public health concern in Orang Asli communities. Severe ascariasis and trichuriasis may lead to other health and medical problems.     

苏省土源性线虫病流行与控制

目的分析总结江苏省土源性线虫病20年来的流行趋势和防治措施,评价防治效果,探讨适合当前流行特点的防治策略和措施。方法收集1990-2009年江苏省土源性线虫病监测、控制措施及防治效果等资料,分析不同阶段的流行特点,评价其防治措施及效果。结果江苏省在不同的防治阶段采取了不同的防治方案。20年来,累计服药防治10 691.66万人次,监测查病204.29万人次。2009年土源性线虫感染率为1.31%,比1990年的59.32%下降了97.79%,表明防治成效十分显著。结论江苏省土源性线虫病流行已得到有效控制。为巩固已取得的防治成果,防治策略应以健康教育、改水改厕和改善环境卫生为主,并继续做好监测、重点人群服药工作以及加强对外来人口土源性线虫病的防治。     

Diversity of mollusks in the Lam Ta Khong reservoir,Nakhon Ratchasima,Thailand

Sampling surveys to study the diversity of mollusks in the Lam Ta Khong reservoir, Nakhon Ratchasima Province, northeast Thailand, were carried out in the hot, rainy and cold seasons. The study area was divided into: Area I--the upper part where the Lam Ta Khong river drains; Area II--the mid-section of the reservoir; Area III--behind the dam. Mollusks were collected from four locations on each bank (to the right and left) of each area. Each location was sampled to include 6 cross-sectional stations; in total, 144 stations were sampled. In the deep water, an Ekman dredge was used to collect samples; the scoop or manual method was used at the water's edge. Ten species of snails and four species of clams were found. The dominant species of snails were: Clea helena, Bithynia siamensis goniomphalos and Melanoides tuberculata; clams were dominated by Corbicula sp. The intermediate host of the human blood fluke was not found. The population of most mollusk species increased during the cold season while that of clams and that of some species of snails increased during the rainy season. Clams and operculate snails predominated in Areas II and III. Pulmonate snails were mostly found close to the bank and on aquatic plants especially in Areas I and II. Operculate snails and clams mainly inhabited water 1 to 10 m deep. Two species of edible mollusks were found: Filopaludina martensi martensi and large numbers of Corbicula. Neither shedding light nor digestion with pepsin A revealed any human parasites in the mollusks sampled.     

Preliminary study on potential circulation of arenaviruses in the rodent population of Nakhon Pathom Province, Thailand and their medical importance in an evoluting environment

Preliminary serological investigations were prefered to detect evidence of arenavirus infection in rodents. The study examined virus antibody in 367 rodents trapped in 6 different geographical areas of Nakhon Pathom Province, Thailand from February-March, 1998. The overall seroprevalence among rodents was 13.3%, mostly in Bandicota savilei (35.7%) and Rattus norvegicus (31.5%). Between ecology, behavior and sex of the rodents, seroprevalence was not significantly different (p>0.05), however the seroprevalence found among different geographical areas of Nakhon Pathom Province were significantly different (p<0.0001).     

江苏省土源性线虫病流行趋势和防治历程

土源性线虫病曾在江苏省广泛流行,严重威胁人民身体健康、阻碍社会经济发展。经过多年积极有效防治,江苏省土源性线虫人群感染率大幅下降,从1989年的59.32%下降至2019年的0.12%,自2013年以来人群土源性线虫感染率均维持在0.5%以下的水平。自1987年以来,江苏省采取土源性线虫病综合防控策略,但各阶段防控措施的侧重点存在差异,主要包括驱虫服药、改水改厕、健康教育和监测与防治效果评估等。至2019年底,全省所有县（市、区）均达到有效控制土源性线虫病标准。今后仍需加强健康教育和监测、落实精准防控,以进一步巩固江苏省土源性线虫病防治成效、消除土源性线虫病对人群的危害。本文对江苏省土源性线虫病流行情况、防控历程及策略演变等进行了回顾与总结。     

金湖县土源性线虫病综合防治效果

目的 目的 评价金湖县土源性线虫病综合防治效果, 为制定防治策略和措施提供依据。方法 方法 1995年起, 采取药物 驱虫、 健康教育、 改水改厕与环境整治等措施, 对土源性线虫病进行综合干预。通过居民土源性线虫感染率、 卫生知识知 晓率和卫生行为正确率等指标评价综合防治效果。结果 结果 1995-2012年, 全县共完成驱虫服药646 437人次, 人均服药 2.48次。自来水受益率97.90%, 农村无害化卫生厕所普及率达86.89%。居民卫生知识知晓率由1996年的54.05%上升至 95.60%, 差异有统计学意义 （χ2 ＝230.92, P＜0.01）, 卫生行为正确率由1996年的59.07%上升至96.40%, 差异有统计学意 义 （χ2 ＝202.69, P＜0.01）。2012年土源性线虫感染率为1.21%, 较1989年的62.57%下降了98.07%, 差异有统计学意义 （χ2 ＝1 016.92, P＜0.01）。蛔虫、 钩虫、 鞭虫感染率分别为0.58%、 1.12%、 0, 较1989年分别下降了94.96%、 97.28%、 100%, 差异均有统计学意义 （χ2 蛔 ＝129.50,χ2 钩 ＝544.62,χ2 鞭 ＝254.19, P均＜0.01）。结论 结论 金湖县通过实施综合防治策略和 相关措施, 有效控制了土源性线虫病的流行。