Intestinal helminth infections among reproductive age women in Vietnam: prevalence, co-infection and risk factors

Intestinal helminth infections are a significant public health problem for Vietnamese women, but prevalence and risk factor data are scarce. The objectives of this paper were to (1) determine the prevalence of helminth infections among women; (2) investigate interactions among intestinal helminth species in individuals and (3) identify risk factors that contribute to intestinal helminth infections. In a nationwide survey conducted in 1995, 9550 households in 53 provinces were covered using a stratified two-stage cluster survey. Stool specimens were examined by Kato-Katz technique. Of 5,127 women, 76% were infected with one or more helminth species, 36% with hookworm, 59% with Ascaris lumbricoides and 28% with Trichuris trichiura. A. lumbricoides and T. trichiura were more likely to be concurrent than expected by chance. There was significant interaction between prevalence and intensity of infection in all three species. All three helminth species were more common in certain ecologic zones than others. Hookworm infection was associated with farming [Odd ratio (OR) = 2.1] and lack of a closed latrine (OR = 2.0), A. lumbricoides with use of untreated feces as fertilizer (OR = 1.2) and coinfection with T. trichiura (OR = 2.1) and T trichiura with A. lumbricoides co-infection (OR = 2.1). Our findings suggest that reproductive-age women, especially rural farmers, should be included among the high priority groups for helminth control programs through mass chemotherapy and improving sanitation.     

Epidemiology of soil-transmitted nematode infections in Ha Nam Province, Vietnam

Baseline epidemiological data are presented from a parasitological survey conducted in Thuy Loi commune, Ha Nam province, Vietnam; a farming community where night soil is routinely used as fertilizer for crops. 177 households were visited and 543 individuals (aged 1–88 years) recruited to the study. Helminth infection intensity was assessed by Kato-Katz to determine the density of parasite eggs per gram of stool (epg). Ascaris lumbricoides, Trichuris trichiura and hookworm infections were the only species detected. 83% of individuals were infected with A. lumbricoides (mean epg = 11971), 94% with T. trichiura (mean epg = 793) and 59% with hookworm (mean epg = 302). Age-dependent patterns of infection prevalence and intensity were similar for A. lumbricoides and T. trichiura , but markedly different for hookworm infection. Similarly, age-dependency in the k-values for the three infections was due to covariance with the respective mean intensities with age rather than to independent age effects, with similar patterns for A. lumbricoides and T. trichiura , and a different pattern for hookworm. Three major conclusions can be drawn from the multiple-species analyses: There is positive interaction between A. lumbricoides and T. trichiura infections; high-intensity A. lumbricoides infections are significantly associated with high-intensity T. trichiura infections; and there is positive interaction between these two species such that infection intensity of A. lumbricoides is higher in individuals with concurrent T. trichiura infection than in individuals without and vice versa.     

Soil-transmitted helminthiases and health behaviors among schoolchildren and community members in a west-central border area of Thailand

The prevalence of soil-transmitted helminthic infections and health behaviors related to infections in schoolchildren and villagers of a community (4 hamlets) was studied in Hauy Kayeng subdistrict, Thong Pha Phum district, in the north of Kanchanaburi Province. The intestinal helminth infection rate of the schoolchildren was 15.6%. Hookworm infection was the most prominent (9.8%), followed by Trichuris trichiura (6.2%), and Ascaris lumbricoides (2.2%). The community showed higher prevalence rates and was infected with more types of intestinal helminths than the schoolchildren. Thirty-five point two percent (35.2%) of the residents were infected with soil-transmitted helminths, 30.5% with hookworm, 3.4% with A. lumbricoides and 2.2% with T. trichiura. Almost all hookworm cases (94.3%) were light intensity infections, while only 1.3% were heavy infections. Moreover, the hookworm infection rate in the community was found to be much higher when a stool culture method was used (39.1%). With this technique, 2.3% Strongyloides stercoralis infections were detected in the community population. Examination of the health behavior of the study samples showed that approximately 75% always defecated in a toilet. Schoolchildren who always wore shoes comprised 67%, which was lower than the community, at 85%.     

Targeting newly enrolled low-age school children for the control of the intestinal helminth infection in rural Nepal

This study aims to identify an effective intervention group for the control of the intestinal helminth infection among school-age children in rural Nepal. We examined 1677 stool samples of school-age children from 25 schools and 1014 samples from 25 communities in rural Nepal. We used formalin-ether sedimentation technique for the microscopic examination of the stool samples and identified three major intestinal helminths: Ascariasis lumbricoides, hookworm and Trichuris trichiura. Our results revealed that the newly enrolled under-6-year-old children at the schools were more widely infected with at least one of the three major helminths than those in the communities (odds ratio [OR] 2.29). We detected a significant difference in the prevalence of A. lumbricoides (OR 1.70), hookworm (OR 2.57) and T.trichiura (OR 3.23) between under-6-year-old children at the schools and those at the communities. The study results suggest that an appropriate deworming programme is needed for the newly enrolled under-6-year-old children in the primary schools in Nepal.     

Intestinal parasitic infection among five interior communities at upper Rejang River,Sarawak, Malaysia

Intestinal parasitic infection among five interior communities at Bakun Valley, upper Rejang River, Sarawak, Malaysia, was investigated as part of a public health impact assessment of the proposed US$ 3 billion Bakun Hydroelectric Project. Coproparasitological examination of 355 stool samples from 7 of 16 villages representing 5 of 7 tribes in the area revealed infection rate of 41%. A higher infection rate was found among the settled Kayans (56%) than the seminomadic Penans (29%). Infection rate was high (68%) among children less than 14 years old. Trichuris trichiura accounted for more than 90% of all infections; less common were Ascaris lumbricoides, hookworms and Strongyloides stercoralis. Polyparasitism was found in 8% of the individuals surveyed with dual infection due to T. trichiura and A. lumbricoides being more common than dual infection with T. trichiura and hookworm. Women had higher infection rates (57%) than men (33%).     

Cross-sectional parasitological survey for helminth infections among fish farmers in Nghe An province, Vietnam

A total of 964 adult fish farmers in five eastern districts in Nghe An province, Vietnam were investigated in late 2004 for food-borne trematodes and other helminth infections using duplicate Kato-Katz thick smears prepared from single stool samples. Eggs of fish-borne trematodes and of Fasciolopsis buski were found in 0.6 and 0.7% of farmers, respectively. Infection prevalences with soil-transmitted helminths (STHs), namely Ascaris lumbricoides, Trichuris trichiura and hookworm, were 34.8, 50.7 and 51.3%, respectively, and 81.8% were infected with at least one of the three STHs. While A. lumbricoides and T. trichiura were more prevalent in the eastern districts compared to the more western districts, the opposite was true for hookworm infections. The widespread prevalence of STH infections in fish farmers suggests that control of these infections in school-age children only may be inadequate. Identification of the human behavioural factors and environmental features responsible for the distribution and frequency of STHs among adults is needed as well as a sensitive diagnostic test of fish-borne trematodes at species level.     

Intestinal parasitic infection and associated symptoms in children attending day care centres in Trujillo,Venezuela

OBJECTIVES: To examine the presence of intestinal protozoan and helminth infections and their association with clinical signs and symptoms in children in Trujillo, Venezuela. METHODS: Conventional microscopic methods (thick-smear, saline and iodine solutions) were used to identify parasites in stool samples of 301 children attending day care centres. A subgroup of 45 children was evaluated clinically and parasitologically five times during a 1-month period using conventional methods and the Kinyoun acid-fast stain for Cryptosporidium identification. RESULTS: The point prevalence of protozoan infections was 21% for Giardia duodenalis, 1.0% for Entamoeba histolytica/dispar, 4% for Entamoeba coli, 16% for Blastocystis hominis, and 89% for Cryptosporidium parvum. Prevalence of helminth infection was 11% for Ascaris lumbricoides, 10% for Trichuris trichiura, 0.3% for Strongyloides stercoralis, and 1.3% for Hymenolepis nana. Over a 1-month time frame, new infections were observed at a rate of 11% for G. duodenalis, 4% for E. histolytica/dispar, 7% for A. lumbricoides, 11% for T. trichiura, 0% for S. stercoralis, and 2% for H. nana. Intestinal symptoms (diarrhoea, vomiting, gas, stomach pain, and loss of appetite) were associated with presence of one or more of C. parvum or B. hominis organisms in stool samples. CONCLUSIONS: Intestinal parasitic infections contribute significantly to the enteric disease burden experienced by this group of children. The organisms most strongly implicated by this study are common and difficult-to-treat protozoan pathogens.     

杭州市3～6岁儿童常见肠道线虫感染现状

于2006年4～6月对杭州市14所幼儿园按分层整群随机抽样调查1 667例3～6岁学龄前儿童的肠道线虫感染情况。用生理盐水直接涂片法和饱和盐水浮聚法检查蛔虫卵、钩虫卵、鞭虫卵。用透明胶纸肛拭法检查蛲虫卵。肠道线虫总感染率为12.96%，其中蛲虫4.44%、蛔虫8.28%、鞭虫0.54%、钩虫0.24%；肠道线虫感染率的高低与幼儿园环境和卫生设施的水平成反比。     

Prevalence of gastrointestinal helminthic infections and associated risk factors among schoolchildren in Tilili town,northwest Ethiopia

Objective:To determine the prevalence of gastrointestinal helminthes and associated risk factors among schoolchildren in Tilili town,northwest Ethiopia.Methods:A cross-sectional study involving 383 schoolchildren was conducted between November 2011 to February 2012.Each student was selected using systematic random sampling method.Questionnaire and observation were used to identify socio-demographic and associated risk factors.Fresh stool samples were observed using formal-ether concentration technique.Data were analyzed using SPSS 16.0statistical software.Results:Four species of intestinal helminthes were identified with an overall prevalence of 44.2%(170 of 385 schoolchildren).The predominant parasites were Ascaris lumbricoides(A.lumbricoides)153(39.7%)and Trichuris trichiura(T.trichiura)30(7.8%).One hundred thirty five(35.1%)had single infections and 35(9.2%)were infected with more than one helminthic parasites in which 32(8.4%)were double infections and 3(0.8%)were triple infections.Significant associations were observed between intestinal helminth infection and those of age,grade level,and school variables.Prevalence of hookworm infection was significant in children who did not wear shoes regularly(P0.05).Conclusions:intervention programs and education on personal and environmental hygiene should be implemented for the prevention and control of helminthic infections in the study area.     

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.     

Prevalence, intensity and risk factors for soil-transmitted helminth infection in a South Indian fishing village

A study of the prevalence, intensity and risk factors for soil-transmitted helminth infection was undertaken among school children aged 5-9 years attending a primary school in the fishing village in Peda Jalaripet, Visakhapatnam, South India. One hundred and eighty nine (92.6%) of 204 children were infected with one or more soil transmitted helminth parasites. The predominant parasite was Ascaris lumbricoides (prevalence of 91%), followed by Trichuris trichiura (72%) and hookworm (54%). Study of age-specific prevalence and intensity of infection revealed that the prevalence and intensity of A. lumbricoides infection was higher among younger children than older children. While aggregation of parasite infection was observed, hookworm infection was more highly aggregated than either A. lumbricoides or T. trichiura. Multivariate analysis identified parental occupation, child's age and mother's education as the potential risk factors contributing to the high intensity of A. lumbricoides infection. Children from fishing families with low levels of education of the mother had the highest intensity of A. lumbricoides infection. As the outcome of chemotherapy programs to control soil transmitted helminth infection is dependant on the dynamics of their transmission, there is a need for further studies to better define the role of specific factors that determine their prevalence, intensity and aggregation in different epidemiological settings.     

Survey for soil-transmitted helminths in Asahan Regency, North Sumatra, Indonesia

The survey on soil-transmitted helminthiasis was carried out in the three villages of Asahan Regency, North Sumatra, Indonesia, between October 1981 and December 1982. The prevalence rates of geohelminthiasis proved to be extremely high (average 97%) in the three villages and more than 70% harboured three or more helminths, especially Ascaris lumbricoides, Trichuris trichiura and hookworm. Necator americanus and Ancylostoma duodenale were detected in 61.1% and 52.2% of 835 fecal specimens, respectively. The effects of two anthelmintics, Combantrin and Trivexan, were essentially the same against A. lumbricoides and hookworm, although Trivexan was better than Combantrin against T. trichiura. The kinetic changes of parasitic infection in community after mass treatment were examined. Ten months after the first drug treatment, the incidence of Ascariasis or trichuriasis reverted nearly to pre-treatment level, while hookworm infection rate remained significantly low. Four months after the second mass treatment, the reinfection rate of A. lumbricoides was most prevalent followed by trichuriasis and hookworm infection. The reinfection rate (63.6%) of A. lumbricoides in children was about six times higher than that (10.4%) in adults at four month after the mass treatment. This study indicates that mass treatment with Trivexan at two month intervals for children and four month intervals for adults is necessary for the effective helminth control scheme in highly endemic areas of North Sumatra.     

Intestinal parasitic infections in schoolchildren in a suburban area of Hanoi, Vietnam

An epidemiological study on intestinal parasitic infections among schoolchildren in a suburban area of Hanoi, Vietnam, was conducted. Of the 217 schoolchildren involved in this study, 166 (76%) were positive for at least one of nine species of parasite (six helminths and three protozoa). Among the helminth parasites, Trichuris trichiura (67%) was detected the most frequently followed by Ascaris lumbricoides (34%) and hookworm (3%). In the case of protozoan parasites, Entamoeba coli (8%) was the most frequently detected followed by E. histolytica (2%). No Cryptosporidium parvum or Cyclospora sp were found. A questionnaire survey revealed that there was no positive relationship between parasite infection and the children's school records, educational background or parental income, which have been known to play a role.     

Impact of intestinal helminth infection on anemia and iron status during pregnancy: a community based study in Indonesia

A cohort study was carried out in Purworejo District, Central Java, Indonesia to investigate prevalence of anemia and low iron stores during pregnancy in relation to intestinal helminth infection. 442 pregnant women were followed until 5-10 weeks postpartum, during the period of April 1996 - August 1998. Information on intestinal helminths, hemoglobin and serum ferritin was collected each trimester. Highest prevalence of anemia in pregnancy (37.1%) was found in the second trimester, while the highest prevalence of low iron stores (49.5%) was found in the third trimester. Most pregnant women (69.7%) were infected with at least one species of pathogenic intestinal helminths. The most common helminth detected was Trichuris trichiura followed by Necator americanus (hookworm) and Ascaris lumbricoides. A significant negative association was found between hookworm infection and serum ferritin at the first trimester (p = 0.010). It is concluded that hookworm infection can interfere iron stores. Other causes of anemia among pregnant women should be considered. Anthelminthic therapy could be given to infected women before conception as public health strategy to improve iron status.     

Soil-transmitted Helminthiasis in the United States: a systematic review--1940-2010

The epidemiology of soil-transmitted helminth infections (hookworm, Trichuris trichiura, Ascaris lumbricoides, and Strongyloides stercoralis) in the United States is poorly understood. To gain understanding of the status of disease, a systematic review was performed to assess the prevalence of soil-transmitted helminth infections in the United States. Of all studies reviewed, 14 were designated as high-quality. High-quality studies were published from 1942 to 1982 and showed that infection was prevalent throughout the southern United States and Appalachia as recently as 1982, finding that hookworm (19.6%), T. trichiura (55.2%), A. lumbricoides (49.4%), and S. stercoralis (3.8%) affected significant percentages of the population. However, because the most recent high-quality studies were published over 25 years ago, the literature does not provide sufficient data to assess current endemic transmission. Because the status of disease remains unclear, there is a need for additional studies to determine if soil-transmitted helminths remain endemic in the United States.     

安徽省人体肠道蠕虫感染现状分析

目的掌握安徽省人体重要寄生虫病流行现状。方法按照全国统一方案，以分层整群随机抽样法调查安徽省10个抽样县(市)，29个土源性线虫调查点，每个点检查500人。采用改良加藤厚涂片法检查肠道蠕虫卵；试管滤纸培养法鉴定钩虫虫种及其它线虫幼虫；透明胶纸肛拭法检查全部12岁以下儿童蛲虫卵。结果．共调查14874人。检出肠道蠕虫13种。总感染率为21．43％，(其中男性19．63％，女性23．37％)，蛔虫、钩虫和鞭虫占全部感染者的91．28％，其中蛔虫、鞭虫和钩虫感染率分别为9．77％、3．14％和9．65％，华支睾吸虫为0．67％(100／14874)；蛲虫阳性率为5．39％(163／3022)；蛔虫和鞭虫感染沿江平原最高，钩虫和华支睾吸虫感染淮北平原最高。结论与我省第一次寄生虫病分布调查相比，发现虫种减少，总感染率及各虫种感染率均大幅度下降。老年龄组的感染率相对较高(尤其是女性)，老年人群在过去的防治中未得到应有的重视。     

Seroprevalence of anti-cysticercus antibodies among the children living in the urban environs of Maputo,Mozambique

Blood and faecal samples were collected from 269 children (aged 0-15 years) who lived in the urban environs of Maputo, the capital city of Mozambique. Antibodies against Cysticercus cellulosae were detected, at a titre of at least 1:100, in 56 (20.8%) of the blood samples. When the stool samples were checked for Taenia solium and other helminths, both as direct smears and after formalin-ether concentration, 180 (67.0%) were found to contain at least one helminth species. The parasites most commonly detected in the faecal samples were Trichurus trichiura (36.0%) and Ascaris lumbricoides (35.7%). Only in one sample (0.4%) were gravid proglottids of Ta. solium detected, but Hymenolepis nana (1.1%) and H. diminuta (0.4%) were also found. A positive correlation between seropositivity for anti-cysticercus antibodies and subject age, and positive associations between such seropositivity and infection with A. lumbricoides and infection with Tr. trichiura were observed. None of the other demographic and environmental factors investigated--the child's sex, religion and access to toilets and/or piped water, the type of house in which he or she lived, the number of individuals in the household to which he or she belonged, and whether that household had pets or raised livestock--showed any apparent association with either the seroprevalence of anti-cysticercus antibodies or infection with any intestinal helminth. The use of water from the common sewage-drainage system for agricultural irrigation in the study area probably causes most of the contamination with intestinal parasites.     

Parasitological survey in Gorontalo North Sulawesi, Indonesia.

A survey for blood and intestinal parasites was carried out in the municipality of Gorontalo on the Minahasa peninsula of North Sulawesi. A total of 156 stool specimens were obtained from 83 males and 73 females. Trichuris trichiura, Ascaris lumbricoides, hookworm, unidentified dicrocoeliid-like ova and Entamoeba coli, in that order, were the most common intestinal parasites detected. Other intestinal parasites found less frequently were Entamoeba histolytica, Iodamoeba bütschlii, Endolimax nana, Giardia lamblia, Enterobius vermicularis and Chilomastix mesnili. Brugia malayi microfilaremiar were detected in 6% and Plasmodium falciparum in less than 1% of the population sampled.     

Intestinal and blood parasites in the North Lore District, Central Sulawesi, Indonesia.

Over 1,000 stool specimens from residents of the Napu and Besoa Valleys, Central Sulawesi, Indonesia were examined. Schistosoma japonicum was detected in 31% of Napu Valley residents while in only 2% of the Besoa Valley residents. Hookworm infections were the most frequently encountered helminth parasitisms in both valleys. Other helminth parasites encountered were: Ascaris lumbricoides, Trichuris trichiura, Enterobius vermicularis, Strongyloides stercoralis, Physaloptera sp., Diphyllobothrium sp., echinostome and heterophyid trematodes. Intestinal protozoa endemic to the area were: Entamoeba histolytica, E. coli, E. hartmanni, Iodamoebe bütschlii, Giardia lamblia, Chilomastix mesnili and Trichomonas hominis. Plasmodium falciparum was responsible for malaria parasitaemias in 5% of 1353 specimens examined and Brugia malayi microfilaraemias were detected in 10% of 972 specimens examined.     

An epidemiological survey on intestinal parasite infection in Khammouane Province, Lao PDR, with special reference to Strongyloides infection

To estimate the current prevalence of intestinal helminth infection in Lao PDR, a parasitological survey was conducted in three villages in Khammouane Province in December 1996, with special reference to Strongyloides infection. A total of 669 fecal samples were collected in the villages and examined by agar-plate culture method and Kato-Katz thick smear method. Intestinal helminths were demonstrated in 82% of the samples as follows: Ascaris lumbricoides (30.5%), Trichuris trichiura (23.7%), hookworm (28.8%), Strongyloides stercoralis (19.0%), Enterobius vermicuralis (3.4%), Opisthorchis viverrini (56.7%) and Taenia sp (3.0%). The infection rates of S. stercoralis were 27.5% and 18.4% in two rural villages, but only 9.4% in an urban village. The highest prevalence rate of Strongyloides infection was obtained in the age group from 20 to 29 years old, although the infection rate already reached 10% in the age group under 10 years old. The prevalence was consistently higher in male subject than females in almost all age groups.