Spatial-temporal clustering analysis of soil-transmitted helminth transmission risk in Jiangxi, 2016-2019 / 中国热带医学

@#Abstract: Objective　To analyze the epidemic characteristics of soil-transmitted helminth (STH) by the spatial epidemiological method in Jiangxi Province. Methods　Surveillance data of STH in Jiangxi Province from 2016 to 2019 were collected for descriptive epidemiological analysis. The space-time permutation distribution of STH infection areas was analyzed with spatial autocorrelation, hotspot analysis methods and retrospective space-time permutation scan statistics. Results　The infection rates of STH were 1.32% (947/71 766), 1.14% (803/70 547), 0.87% (604/69 507) and 0.90% (628/69 620), respectively, and the differences were statistically significant in different years (P<0.01). The rates of hookworm infection were 0.65% (466/71 766), 0.64% (450/70 547), 0.48% (336/69 507) and 0.52% (362/69 620), respectively, and the differences were statistically significant (P<0.01). The infection rates of Ascaris lumbricoides were 0.55% (393/71 766), 0.41% (287/70 547), 0.32% (221/69 507) and 0.32% (225/69 620), respectively, and the differences were statistically significant in different years (P<0.01). The infection rates of Trichuris trichiura were 0.17% (125/71 766), 0.10% (74/70 547), 0.08% (57/69 507) and 0.07% (49/69 620), respectively, and the differences were statistically significant among different years (P<0.01). The results of global spatial autocorrelation analysis showed that there was a spatial autocorrelation index Moran's I value of hookworm infection rate in 2016, Trichuris trichiura infection rate in 2016, 2018 and 2019, with statistical significance (P<0.05). The results of hotspot analysis, SaTScan and FleXScan spatial and temporal scanning analysis showed that there were high-value aggregation regions for each species in each year. Conclusion　The infection rates of STH, hookworm, Ascaris lumbricoides and Trichuris trichiura showed a decreasing trend and space-time clustering from 2016 to 2019. It should be taken into account in the formulation of control strategies.

Boarding School: A Simple Approach To Reduce Soil Transmitted Helminth Infections In Orang Asli Children Of Sungai Siput, Perak, 2017

@#Soil transmitted helminth (STH) infection is a major public health concern among the indigenous children of Malaysia. Precarious living conditions at home including unavailability of water, drinking of contaminated water, poor sanitation and livestock presence, are known risk factors for the infection. In order to provide better living conditions, these children are enrolled in boarding schools. This study was conducted to determine whether boarding schools is a solution in reducing soil transmitted helminth infection among Orang Asli children in Sg Siput, Perak, Malaysia. An analytical cross-sectional study was conducted among 204 schoolchildren aged 7-17 years from three boarding schools in Sungai Siput, Perak from January to March 2017. Stool samples were collected and examined using direct smear and Kato-Katz technique. Information on sociodemographic and environmental conditions were collected using a modified Demographic Health Survey (DHS) questionnaire. Data analysis was done using IBM SPSS Statistics Processor 20.0.Out of a total of 204 children, only 48% (n= 97) were infected with at least one type of STH species which showed a reduced prevalence as compared to previous studies conducted among home dwelling schoolchildren with overall prevalence of 78-97%. Majority of the children had monoparasitism (31%; n=63) with moderate intensity by T trichuira (n=51, 25%). Univariate analysis shows that unavailability of water at home has a statistically significant association with STH infection among boarding school children (OR=0.73; 95% CI= 0.56-0.95 p=0.021). Multivariate analysis proves children who had unavailability of water at home has 2.1 times more likelihood of getting an STH infection (OR= 2.08; 95%CI= 1.07-4.07; p= 0.032).This study demonstrates a reduced STH prevalence among Orang Asli boarding school children as better living condition there limits the spread of STH infection among them.

Epidemiological Characteristics of Strongyloidiasis in Inhabitants of Indigenous Communities in Borneo Island, Malaysia

Epidemiological study on strongyloidiasis in humans is currently lacking in Malaysia. Thus, a cross-sectional study was carried out to determine the prevalence of Strongyloides stercoralis infection among the inhabitants of longhouse indigenous communities in Sarawak. A single stool and blood sample were collected from each participant and subjected to microscopy, serological and molecular techniques. Five species of intestinal parasites were identified by stool microscopy. None of the stool samples were positive for S. stercoralis. However, 11% of 236 serum samples were seropositive for strongyloidiasis. Further confirmation using molecular technique on stool samples of the seropositive individuals successfully amplified 5 samples, suggesting current active infections. The prevalence was significantly higher in adult males and tended to increase with age. S. stercoralis should no longer be neglected in any intestinal parasitic survey. Combination of more than 1 diagnostic technique is necessary to increase the likelihood of estimating the ‘true’ prevalence of S. stercoralis.

Epidemiological Characteristics of Strongyloidiasis in Inhabitants of Indigenous Communities in Borneo Island, Malaysia

Epidemiological study on strongyloidiasis in humans is currently lacking in Malaysia. Thus, a cross-sectional study was carried out to determine the prevalence of Strongyloides stercoralis infection among the inhabitants of longhouse indigenous communities in Sarawak. A single stool and blood sample were collected from each participant and subjected to microscopy, serological and molecular techniques. Five species of intestinal parasites were identified by stool microscopy. None of the stool samples were positive for S. stercoralis. However, 11% of 236 serum samples were seropositive for strongyloidiasis. Further confirmation using molecular technique on stool samples of the seropositive individuals successfully amplified 5 samples, suggesting current active infections. The prevalence was significantly higher in adult males and tended to increase with age. S. stercoralis should no longer be neglected in any intestinal parasitic survey. Combination of more than 1 diagnostic technique is necessary to increase the likelihood of estimating the ‘true’ prevalence of S. stercoralis.

Prevalence of Soil-Transmitted Helminths and Molecular Clarification of Hookworm Species in Ethnic Ede Primary Schoolchildren in Dak Lak Province, Southern Vietnam

To know the infection status of helminths in primary schoolchildren of southern parts of Vietnam, we performed an epidemiological study in Krong Pac district, Dak Lak Province, Vietnam. A total of 1,206 stool specimens were collected from ethnic Ede schoolchildren in 4 primary schools in 2015 and examined by the Kato-Katz technique. In addition, stool cultures were done by the Harada-Mori method to obtain hookworm larvae and then to clarify the species of hookworms infected. The results showed that the helminth infection rate was 25.0%, including 2.0% Ascaris lumbricoides, 0.33% Trichuris trichiura, and 22.8% hookworm infections. The average intensity of infection was 102.0 eggs per gram of feces (EPG) for Ascaris, 36.0 EPG for Trichuris, and 218.0 EPG for hookworms. ITS1 gene sequences of the hookworm larvae were identical with those of Necator americanus (100% homology) reported in GenBank. It has been confirmed in this study that the hookworm, N. americanus, is a dominant helminth species infected in primary schoolchildren of a southern part of Vietnam. Public health attention is needed for control of hookworm infections among schoolchildren in surveyed areas of Vietnam.

Impact on prevalence of intestinal helminth infection in school children administered with seven annual rounds of diethyl carbamazine (DEC) with albendazole.

Background & objectives: One third of the world’s population is infected with one or more of the most common soil-transmitted helminths (STH). Albendazole (ALB) is being administered with diethyl carbamazine (DEC) in filariasis endemic areas to eliminate lymphatic filariasis (LF) and helminth infections. In this study, the cumulative impact of seven annual rounds of mass drug administrations (MDA) of DEC and ALB on STH infection in school children in selected villages in southern India was determined. Methods: During 2001-2010, seven MDAs were implemented by the Tamil Nadu state health department, India. LF and STH infections were monitored in school children from 18 villages of the two treatment arms (viz, DEC alone and DEC+ALB). Kato-Katz cellophane quantitative thick smear technique was employed to estimate STH infections at three weeks, six months and one year post MDA. Results: Prior to treatment, an overall STH prevalence was 60 per cent. After each MDA, infection markedly reduced at three weeks post-treatment in both the arms. The prevalence increased at six months period, which was maintained up to one year. After seven rounds of MDA, the infection reduced from 60.44 to 12.48 per cent in DEC+ALB arm; while the reduction was negligible in DEC alone arm (58.77 to 52.70%). Interpretation & conclusions: Seven rounds of MDA with DEC+ALB reduced the infection load significantly, and further sustained low level of infection for 10 years. However, complete parasite elimination could not be achieved. To curtail STH infection in the community, MDA should be regularized and environmental sanitation measures need to be improved by effective community-based campaigns.

Prevalence of Schistosomes and Soil-Transmitted Helminths among Schoolchildren in Lake Victoria Basin, Tanzania

The objectives of this study was to conduct a survey on schistosomiasis and soil-transmitted helminth (STH) infections in order to come up with feasible control strategies in Lake Victoria basin, Tanzania. Depending on the size of the school, 150-200 schoolchildren were recruited for the study. Duplicate Kato-Katz stool smears were prepared from each child and microscopically examined for Schistosoma mansoni and STHs. Urine specimens were examined for Schistosoma haematobium eggs using the filtration technique. After the survey, mass drug administration was done using praziquantel and albendazole for schistosomiasis and STHs infections, respectively. A total of 5,952 schoolchildren from 36 schools were recruited for the study and had their stool and urine specimens examined. Out of 5,952 schoolchildren, 898 (15.1%) were positive for S. mansoni, 754 (12.6%) for hookworms, 188 (3.2%) for Ascaris lumblicoides, and 5 (0.008%) for Trichuris trichiura. Out of 5,826 schoolchildren who provided urine samples, 519 (8.9%) were positive for S. haematobium eggs. The results revealed that intestinal schistosomiasis, urogenital schistosomiasis, and STH infections are highly prevalent throughought the lake basin. The high prevalence of intestinal and urogenital schistosomisiasis in the study area was a function of the distance from Lake Victoria, the former being more prevalent at localities close to the lake, whilst the latter is more so away from it. Control of schistosomiasis and STHs in the study area requires an integrated strategy that involves provision of health education to communities, regular treatments, and provision of adequate safe water supply and sanitation facilities.

Prevalence of Schistosomes and Soil-Transmitted Helminths and Morbidity Associated with Schistosomiasis among Adult Population in Lake Victoria Basin, Tanzania

The objective of this study was to carry out a community survey on schistosomiais and soil-transmitted helminth (STH) infections in order to suggest feasible and effective intervention strategies in Lake Victoria basin, Tanzania. A total of 37 communities selected from 23 districts of the 4 regions in the Lake Victoria basin of Tanzania were involved in the study. From each of the selected locality, 50 adult community members, 25 males and 25 females, were recruited for the study. Each study participant was requested to submit stool and urine specimens. From each stool specimen, duplicate Kato-Katz thick smears were prepared and microscopically examined for Schistosoma mansoni and STH eggs. Urine specimens were processed by the filtration technique and microscopically examined for Schistosoma haematobium eggs. Ultrasound examination for morbidity due to schistosomiasis was performed. Mass treatment was done using praziquantel and albendazole for schistosome and STHs infections, respectively. Out of 1,606 adults who provided stool specimens, 199 (12.4%) were positive for S. mansoni, 349 (21.7%) for hookworms, 133 (8.3%) for Ascaris lumbricoides, and 33 (2.0%) for Trichuris trichiura. Out of 1,400 participants who provided urine specimens, 25 (1.8%) were positive for S. haematobium eggs. Because of the co-endemicity of these afflictions and their impact on vulnerable population groups, the helminthiasis could be simultaneously treated with 2 drugs, praziquantel for schistosomiasis and albendazole for STHs.

SITUATION OF SOIL-TRANSMITTED HELMINTH INFECTION IN EDE ETHNIC IN EA TIEU COMMUNE OF DAKLAK PROVINCE

Background: Each of the zone there has a different context for soil-transmitted helminth disease to exist and develop. Objectives: (1) To define the soil-transmitted helminth infection prevalence situation. (2) To define knowledge and practice about soil-transmitted helminth diseases prevention in Ea Tieu commune. Subject and method: The Ede ethnic population community lives in Ea Tieu and using a cross-sectional study. Results and conclusions: Ea Tieu commune, Krong Ana district, Daklak province, that has rather high soil-transmitted helminth general prevalence about 74.1 %, the highest prevalence is Ascaris lumbricoides infection, about 53.7%, next is hookworm with 38.4%, and the lowest is Trichuris trichiura with 1.3%. The Ascaris lumbricoides infection prevalence is not that different between age group (2 - 15: 58.98% in comparison with over 16: 50.87%) and hookworm infection prevalence was different between two age group that are 2-15: 6.05% which is lower than over 16: 55.99%. Average of intensity infection (average of eggs per gram of faeces) belongs to low intensity infection. Knowledge and practice about worm infection prevention of Ede ethnic in Ea Tieu is very low: 29.8% people does not rightly know of any harm, 24.6% people know one of the reasons is because of unclean food, 16.3% and another reason because of unclean hands with 16.3%, only 6.1 % people know the reason for hookworm infection.

A successful experience of soil-transmitted helminth control in the Republic of Korea

Soil-transmitted helminths (STH), namely Ascaris, Trichuris and hookworms (Ancylostoma and Necator), present a global health problem to about a half of the earth's population. In the Republic of Korea, STH were highly prevalent and were considered a high priority target for national control. To promote the control, a non-governmental organization named Korea Association for Parasite Eradication (currently Korea Association of Health Promotion) was founded in 1964, and mass fecal examination followed by selective mass chemotherapy with anthelmintics was performed twice a year from 1969 to 1995 targeting whole nationwide schoolchildren. Meanwhile, decreasing patterns of national STH infections have been monitored by 7 times' quinquennial national surveys targeting general population. In 1971, the overall intestinal helminth egg positive rate was 84.3% (Ascaris 58.2%, Trichuris 65.4%, and hookworms 10.7%), which became 63.2% in 1976, 41.1% in 1981, 12.9% in 1986, 3.8% in 1992, 2.4% in 1997, and 4.3% (Ascaris 0.03%, Trichuris 0.02%, and hookworms 0%) in 2004. During the control period, national economy rapidly developed, and living standards including environment, sanitation, and agricultural technology greatly improved, which undoubtedly boosted the STH control effects. Our experience indicates that social driving force to establish an eligible national control system to conduct repeated mass chemotherapy, together with improvement of environment and sanitation, is important for initiating and achieving STH control in a developing community.