A comparative study of different albendazole and mebendazole regimens for the treatment of intestinal infections in school children of Usigu Division, western Kenya

A clinical trial to compare the effectiveness of 4- and 6-mo repeated treatment with albendazole 600 mg (Zentel, SmithKline Beecham) or mebendazole 600 mg (Vermox, Janssen) on geohelminth infections was carried out on children in 6 primary schools; the study included 1,186 children, ages 4 to 19 yr. Kato-Katz examination was performed on stool samples before and after treatment. Overall, albendazole produced better cure rates and egg reduction rates for geohelminths. The cure rates for albendazole were 92.4% for hookworm infection, 83.5% for Ascaris lumbricoides, and 67.8% for Trichuris trichiura. Mebendazole given either 2 or 3 times in a year had cure rates of 50 and 55.0% (respectively) for hookworm, 79.6 and 97.5% for A. lumbricoides, and 60.6 and 68.3% for T. trichiura infection. The geometric mean intensity of hookworm eggs per gram (epg) of stool decreased by 96.7% after albendazole treatment compared with 66.3 and 85.1%, respectively, for 2 or 3 doses of mebendazole (P < 0.05) over the same period. Reductions in epg for A. lumbricoides and T. trichiura were comparable for both drugs. Our results indicate that treatment with albendazole at a 6-mo interval was more effective than mebendazole regimens and may be the best choice for use in the control of the 3 geohelminths.     

Comparison of the Kato-Katz and FLOTAC techniques for the diagnosis of soil-transmitted helminth infections

Decisions on individual or community treatment and evaluation of chemotherapy based control programs depend on parasitological diagnostic techniques. The aim of this study was to compare the accuracy of a single Kato-Katz thick smear and a single FLOTAC for the determination of the prevalence and intensity of soil-transmitted helminth infections. A total of 271 faecal specimens were collected from schoolchildren in Ethiopia, and microscopically examined using the Kato-Katz method (41.7 mg stool per slide) and the FLOTAC technique. The combined results from the Kato-Katz and FLOTAC methods were used as diagnostic 'gold' standard for reference in the analysis. Agreement between the two methods showed kappa values of 0.74, 0.73 and 0.28 for Ascaris lumbricoides, Trichuris trichiura and hookworm, respectively. A single FLOTAC revealed significantly more infections than a single Kato-Katz for each of the three soil-transmitted helminths (p<0.01). The sensitivities of a single Kato-Katz for diagnosis of T. trichiura, A. lumbricoides and hookworm infections were 76.6%, 67.8% and 19.6%, respectively, while the sensitivity of FLOTAC was 100% for all the three soil-transmitted helminth species. A single Kato-Katz yielded considerably higher mean faecal egg counts (FECs) (729.1, 145.2 and 60.7 eggs per gram of stool (EPG) for A. lumbricoides, T. trichiura and hookworm, respectively) compared with a single FLOTAC (142.5, 54.5 and 14.6 EPG, respectively) (p<0.05). Our study confirms that a single FLOTAC is more sensitive than a single Kato-Katz for the diagnosis of soil-transmitted helminth infections, but results in lower FECs. Further standardization and validation are still required in different epidemiological settings with varying levels of intensity of infections before recommending FLOTAC for large-scale community diagnosis.     

Prevalence and intensity of infections of Ascaris lumbricoides and Trichuris trichiura and associated socio-demographic variables in four rural Honduran communities

Between January and March 1998, a cross-sectional survey was carried out in four rural communities in Honduras, Central America. We examined the prevalence and intensity of Ascaris lumbricoides and Trichuris trichiura infections among 240 fecal specimens, and the association between selected socio-demographic variables and infection for 62 households. The overall prevalence of A. lumbricoides and T. trichiura was 45% (95% CI 39.0-51.9) and 38% (95% CI 31.8-44.4) respectively. The most intense infections for Ascaris and Trichuris were found in children aged 2-12 years old. By univariate analysis variables associated with infections of A. lumbricoides were: number of children 2-5 years old (p=0.001), level of formal education of respondents (p=0.01), reported site of defecation of children in households (p=0.02), households with children who had a recent history of diarrhea (p=0.002), and the location of households (p=0.03). Variables associated with both A. lumbricoides and T. trichiura infection included: number of children 6-14 years old (p=0.01, p=0.04, respectively), ownership of a latrine (p=0.04, p=0.03, respectively) and coinfection with either helminth (p=0.001, p=0.001, respectively). By multivariate analysis the number of children 2-5 years living in the household, (p=0.01, odds ratio (OR)=22.2), children with a recent history of diarrhea (p=0.0, OR=39.8), and infection of household members with T. trichiura (p=0.02, OR=16.0) were associated with A. lumbricoides infection. The number of children 6-14 years old in the household was associated with both A. lumbricoides and T. trichiura infection (p=0.04, p=0.01, OR=19.2, OR=5.2, respectively).     

Modes of transmission for Ascaris lumbricoides and Trichuris trichiura among Chinese children in Macao City

To obtain more information on the transmission of Ascaris lumbricoides and Trichuris trichiura in Macao City, 308 Chinese children were surveyed. The infection rates of A. lumbricoides and T. trichiura were 14.9 and 6.8%, respectively. There was no association between the infections. A. lumbricoides infection was associated with age and T. trichiura with new immigrants from China. No association was found between the infections and family socio-economic factors. The results suggest that the modes of transmission for A. lumbricoides and T. trichiura may be different in highly urbanized areas.     

Multiple infection diagnosis of intestinal helminthiasis in the assessment of health and environmental effect of development projects in Nigeria

Patterns of intestinal helminth infections among school-aged children have been assessed in Eko-ende and Ore, as part of an overall assessment of the public health impact of Erinle Dam Reservoir in Osun State, Nigeria. The investigation was carried out between January and May 2005 using the Kato Katz thick smear technique and simple questionnaire for information on the bio-data, knowledge, attitude and practice of individuals towards disease transmission and control. Ascaris lumbricoides, hookworm, Trichuris trichiura, Taenia spp., Strongyloides stercoralis and Schistosoma mansoni were recovered at an overall prevalence of 78.3% among 309 children examined. Ascaris lumbricoides, hookworm, T. trichiura and S. mansoni were the most common infections while S. stercoralis and Taenia spp. were found only among a few children. Infection patterns of the common diseases were age-specific with peaks in the 11-15 age bracket. Children not attending school were significantly (P < 0.05) more at risk of infection than those attending school. Multiple infections were pronounced with over 54% double infections and 6% four parasites or more infections. The need for urgent intervention to arrest the obviously serious public health situation attributable to Erinle Dam is emphasized.     

Prevalence and intensity of soil-transmitted helminthiasis in the city of Portoviejo (Ecuador).

We studied the stool samples of 151 school children in a district of the city of Portoviejo (Ecuador) in order to determine the prevalence and intensity of soil-transmitted helminthiasis (STH) and their relationships with anthropometric indices. The samples were analyzed with the semiquantitative Kato-Katz technique and the intensity of infections was categorized as light, moderate or high according to the thresholds set by the World Health Organization. Prevalence of soil transmitted helmintiasis was 65% (92 out of 141 collected samples), Ascaris lumbricoides was the most common STH (63%) followed by Trichuris trichiura (10%) and hookworm (1.4%). Heavy intensity infections were found in 8.5% of the stool samples, with T. trichiura showing higher worm burdens than A. lumbricoides. Sixteen percent of the children were below the third percentile for weight (wasted), while 27% were below the third percentile for height (stunted). A significant relationship was found between the worm burden and the degree of stunting. This study suggests that the periodic administration of an antihelminthic drug should be targeted to preschool and school children to allow a normal growth spurt and prevent stunting.     

Species-specific treatment effects of helminth/HIV-1 co-infection: a systematic review and meta-analysis

In sub-Saharan Africa, over 22 million people are estimated to be co-infected with both helminths and HIV-1. Several studies have suggested that de-worming individuals with HIV-1 may delay HIV-1 disease progression, and that the benefit of de-worming may vary by individual helminth species. We conducted a systematic review and meta-analysis of the published literature to determine the effect of treatment of individual helminth infections on markers of HIV-1 progression (CD4 count and HIV viral load). There was a trend towards an association between treatment for Schistosoma mansoni and a decrease in HIV viral load (Weighted mean difference (WMD)=-0·10; 95% Confidence interval (CI): -0·24, 0·03), although this association was not seen for Ascaris lumbricoides, hookworm or Trichuris trichiura. Treatment of A. lumbricoides, S. mansoni, hookworm or T. trichiura was not associated with a change in CD4 count. While pooled data from randomized trials suggested clinical benefit of de-worming for individual helminth species, these effects decreased when observational data were included in the pooled analysis. While further trials are needed to confirm the role of anthelmintic treatment in HIV-1 co-infected individuals, providing anthelmintics to individuals with HIV-1 may be a safe, inexpensive and practical intervention to slow progression of HIV-1.     

Familial aggregation of human susceptibility to co- and multiple helminth infections in a population from the Poyang Lake region, China

Human helminthiases are common in China, especially in rural areas where sanitation conditions are poor. Co- and multiple infections with helminths are strikingly frequent. A cross-sectional parasitological and questionnaire survey was carried out in a population of 3205 individuals belonging to 498 families from five villages in the Poyang Lake region, Jiangxi Province, China, to assess their helminth infection status and to collect information on risk factors for infection. The prevalences for Ascaris lumbricoides, Schistosoma japonicum and Trichuris trichiura were 30.9%, 15.7% and 47%, respectively. Hookworm infection prevalence was low (0.7%). A significant association was observed between A. lumbricoides and T. trichiura infection, and also between S. japonicum and T. trichiura infection. Variance components analysis was undertaken to investigate the aggregation of S. japonicum and the soil-transmitted helminths, A. lumbricoides and T. trichiura. While A. lumbricoides was found to aggregate only at a household level, T. trichiura was shown to cluster predominantly in families. Both genetic and household effects were found to be important in determining the risk of infection with S. japonicum. Variance components analysis for A. lumbricoides/T. trichiura co-infections indicated a significant domestic environmental effect, attributable for 32.7% of the co-infection risk. Aggregation of S. japonicum/T. trichiura co-infection was also observed at a household level. The risk of infection with multiple helminth species, although mainly environmentally influenced, was also shown to have significant involvement of genetic and household components. The results of this study indicate that a shared household is a major contributing risk factor for helminth co-infections and emphasises the need for increased standards of sanitation and hygiene to prevent parasite transmission. Further, the results suggest that susceptibility to one helminth infection is not completely independent of another, and that there exist common genetic factors underlying infection with multiple helminth species.     

Cytokine response profiles predict species-specific infection patterns in human GI nematodes

This study investigated associations between pre-treatment cytokine expression and infection patterns, before and after de-worming, in humans exposed to two gastrointestinal nematode species. Quantitative measures of Ascaris lumbricoides and Trichuris trichiura infection (based on faecal egg counts) were estimated immediately before and 8-9 months after treatment in a Cameroonian population. Whole blood cytokine responses to parasite-derived antigens were assayed immediately pre-treatment. An overall measure of the tendency towards species-specific infection (increasing with A. lumbricoides faecal egg counts and decreasing with T. trichiura faecal egg counts) was significantly positively related to IL-10 levels in older (14-57 year) hosts. There was a significant negative influence of IL-5 on reinfection probability in T. trichiura but not A. lumbricoides. This effect coincided with reduced reinfection success in T. trichiura compared to A. lumbricoides. T(H)2 cytokine expression by younger hosts (4-13 year) was negatively associated with contemporary A. lumbricoides faecal egg counts before treatment. Following treatment, the pre-treatment T(H)2 cytokine expression data for younger hosts (now reflecting responsiveness 8-9 months in the past) were negatively associated with T. trichiura faecal egg counts. Taken together, these observations suggest a successional interaction between T(H)2-driven immune responses and species infection over time. However, any differential effects of the measured immune responses on species-specific recruitment, maturation and mortality were superimposed upon (and outweighed by) the effects of other factors favouring coinfection.     

Seroprevalence of Toxocara canis-IgG antibodies in two rural Bolivian communities

A survey on toxocara canis-IgG seroprevalence was carried out in two Bolivian communities (Mora and Zanja Honda) living in the Cordillera Province, Department of Santa Cruz. Two hundred and sixteen people, both males and females, 2 to 85 years old were sampled. Altogether, 73 people were positive (34%). The seroprevalence was 27% in Mora and 42% in Zanja Honda (p = 0.022). No statistical correlations were found with sex and age. High prevalences were also found for intestinal helminths (hookworms, Trichuris trichiura, Ascaris lumbricoides, Hymenolepis nana and Strongyloides stercoralis). Positive association between T. canis seropositivity and presence of T. trichiura and between T. trichiura and hookworms were found. T. canis egg prevalence in dog population was found consistently higher in Zanja Honda than in Mora (40% vs 27%).     

Intestinal parasite infections among inhabitants in two islands of Tongyeong-gun, Kyeongsangnam-do

This study was performed to evaluate the status of intestinal parasitic infections among the inhabitants in two islands (Chu-do and Doomi-do) of Tongyeong-gun, Kyeongsangnam-do (Province), from August to September, 1989. A total of 189 stool specimens was collected from the inhabitants of 3 villages and examined by Kato's cellophane thick smear and formalin-ether sedimentation techniques. Stoll's dilution egg counting technique was done for the quantitative examination of helminth eggs. The overall positive rate of intestinal parasites was 30.2%. The egg positive rate of Ascaris lumbricoides was 2.1%, that of Trichuris trichiura 24.3%, hookworm 2.1%, Trichostrongylus orientalis 0.5%, Clonorchis sinensis 1.1%, heterophyid 1.6%, and Taenia species 2.6%. The cyst positive rate of Giardia lamblia was 1.6% and that of Entamoeba coli 0.5%. In T. trichiura infection, the egg positive rate of females (29.9%) was much higher than that of males (17.2%). Among the age groups, 10-19 year group showed the highest infection rate, 32.4%. It was revealed that the prevalence of intestinal parasitic infections among the inhibitants of remote islands should be still high in comparison with ever-reported ones in urban or rural areas.     

Malaria, schistosomiasis, and intestinal helminths in relation to microdams in Tigray, northern Ethiopia.

A survey was undertaken in Tigray, Northern Ethiopia, to assess the prevalence of malaria, schistosomiasis, and intestinal helminths in relation to microdams. The survey took place from March to June 1995, during the dry season, at 41 microdams. At each site the village nearest the dam (within thirty minutes walk) was selected, ten households were randomly chosen, and all family members were examined for malaria and intestinal parasites. The overall study sample was 2271 people, of all age groups. Plasmodium falciparum infection was documented in four villages (at 10% of microdams); prevalence was 1.2% (range 0-20% by village). Larvae of Anopheles gambiae s.l. were found at one microdam. Infection with intestinal schistosomiasis was documented in 20 villages (at 49% of microdams), and one third of those infected had moderate to heavy infections. Biomphalaria species, the intermediate host snails of Schistosoma mansoni, were found at 16 microdams (39%), and snails infected by mammalian cercariae were found in one locality. Infections with soil-transmitted nematodes were prevalent: hookworm was detected in more than two thirds of the villages, and Ascaris lumbricoides and Trichuris trichiura were present in almost half of the villages. Out of 2078 stool examinations, the prevalence of S. mansoni infection was 7.2% (range 0-48% by village), of A. lumbricoides 2.3% (range 0-31%), of T. trichiura 2.4% (range 0-21%), and of hookworm 8.9% (range 0-78%). The prevalence of malaria, S. mansoni and hookworm was higher at altitudes below 2000 metres above sea level. S. mansoni was more prevalent in microdams built more than 5 years before the survey, while T. trichiura was more prevalent at recently constructed microdams. The widespread distribution of schistosomiasis and intestinal helminths, and the presence of malaria infection during the dry season confirm that microdams create favourable conditions for the transmission of these parasitic diseases. Health safeguards must be incorporated into the planning, construction, and operation of microdams and irrigation systems in order to prevent or reduce these diseases. In areas with high prevalence, control activities should be intensified.     

The role of some cyclorrhaphan flies as carriers of human helminths in Malaysia

The role of some adult flies (Diptera: Cyclorrhapha) as carriers of helminth parasites of man was studied at four sites in Malaysia: a refuse dump, where no helminth-positive flies were detected, and in three peri-domestic situations where four species of flies carried up to three types of nematodes. The dominant fly species Chrysomya megacephala (Fabricius) carried eggs of the roundworm Ascaris lumbricoides L., the pinworm Trichuris trichiura (L.) and hookworm on the adult external body surface and in the gut lumen, in association with Bukit Lanjan aborigines. Chrysomya rufifacies (Macquart) and Sarcophaga spp. also had Ascaris lumbricoides and Trichurus trichiura eggs in their gut contents. Human helminths were not recovered from Lispe leucospila (Wiedemann), Lucilia cuprina (Wiedemann) or the housefly Musca domestica L. In an urban slum area of Kuala Lumpur city, filariform larvae identified as the hookworm Necator americanus (Stiles) occurred in the intestines of the face-fly Musca sorbens Wiedemann (22 larvae per 100 flies) and of Chrysomya megacephala (4.5 larvae per 100 flies). This concentration of apparently infective N. americanus in M. sorbens, a fly which often breeds in faeces and browses on human skin, could have transmission potential.     

Status of intestinal parasite infections among children in Bat Dambang, Cambodia

A survey was conducted to determine the extent of intestinal parasite infection in Bat Dambang, Cambodia in March 2004. A total of 623 fecal specimens was collected from kindergarten and schoolchildren and examined using the formalin-ether sedimentation technique. The overall infection rate of intestinal parasites was 25.7% (boys, 26.2%; girls, 25.1%), and the infection rates of intestinal helminthes by species were as follows: Echinostoma sp. 4.8%, hookworm 3.4%, Hymenolepis nana 1.3%, and Rhabditis sp. 1.3%. The infection rates of intestinal protozoa were; Entamoeba coli 4.8%, Giardia lamblia 2.9%, Iodamoeba butschlii 1.4%, Entamoeba polecki 1.1%, and Entamoeba histolytica 0.8%. There were no egg positive cases of Ascaris lumbricoides or Trichuris trichiura. All children infected were treated with albendazole, praziquantel, or metronidazole according to parasite species. The results showed that intestinal parasites are highly endemic in Bat Dambang, Cambodia.     

Intestinal helminths in a population of children from the Kashmir valley, India

In any geographical area, surveys of the prevalence of intestinal helminths are necessary to suggest appropriate control measures. The aim of this study was to determine the prevalence of intestinal helminth infections in children of the Kashmir valley and to identify the risk factors. Stool samples were collected from 2256 children from rural as well as urban areas of the Kashmir valley. The samples were examined by simple smear and zinc sulphate concentration methods. Intensity of the infection was quantified by Stoll's egg-counting technique. Infection by at least one intestinal helminth was found in 71.18% of the sampled population. The prevalence of Ascaris lumbricoides was highest (68.30%), followed by Trichuris trichiura (27.92%), Enterobius vermicularis (12.67%) and Taenia saginata (4.60%). Light (57.1%) to moderate (42.8%) intensity of infection was observed for A. lumbricoides, while the majority of the infected children (92.3%) harboured a light intensity of infection for T. trichiura. The age group, rural or urban residence, type of water source, boiled or unboiled water, type of defecation site, level of personal hygiene and maternal education were associated with helminth infection. Adequate control measures are urgently needed to combat the high prevalence of intestinal helminths and risk factors in the children of Kashmir valley.     

Status of intestinal parasites infection among primary school children in Kampongcham,Cambodia

A survey was made to find the extent of intestinal parasite infection in Kampongcham, Cambodia in February 2002. A total of 251 fecal specimens were collected from Tonlebat primary school children and examined by formalin-ether sedimentation technique. The overall infection rate of intestinal parasite was 54.2% (males, 57.3%; females, 50.8%). The infection rate of intestinal helminths by the species were as follows: Ascaris lumbricoides 26.3%, Echinostoma sp. 15.6%, hookworm 6.4%, Opisthorchis sp. 4.0%, Rhabditis sp. 2.4%, and Trichuris trichiura 0.4%. The infection rate of intestinal protozoa were as follows: E. coli 7.6%, G. lamblia 3.2%, I. butschlii 3.2%, and E. histolytica 0.8%. More than two different kinds of parasites were found in 16.7% of the stool samples. All the children infected were treated with albendazole, praziquantel and metronidazole according to parasite species. The results showed that intestinal parasites are highly endemic in this area.     

Infection status of intestinal parasites in children living in residential institutions in Metro Manila, the Philippines

A small scale survey was performed to know the infection status of intestinal parasite in children of the residential institutions and street communities in Metro Manila, Philippines. A total of 284 stool samples from 11 institutions and 3 street communities was examined by the formalin-ether concentration method. The scotch tape anal swab was adapted to 121 children to investigate the infection status of Enterovius vermicularis. It was found out that 62.0% of the children examined were positive for one or more intestinal parasites. Multiple infections were observed in 34.2% of the children. Among 172 children who gave detail information, the prevalence for Ascaris lumbricoides, Trichuris trichiura, and hookworm was 36.0%, 44.8%, and 7.0% respectively. Of the children examined, 47.7% were found to be harboring parasitic protozoans such as Entamoeba histolytica, Giardia lamblia, and Blastocystis hominis. The most prevalent of these protozoans was B. hominis with an infection rate of 40.7%. The prevalence of these infections among children living in institutions was relatively high. More efforts should be made to implement anthelminthic programs including bi-annual follow-up treatments.     

Impact of community-directed treatment on soil transmitted helminth infections in children aged 12 to 59 months in Mazabuka District, Zambia

This study assessed the impact of adding community-directed treatment (ComDT) to the routine health facility (HF)-based treatment on prevalence and intensity of soil transmitted helminth (STH) infections among children aged 12 to 59 months. Repeated cross-sectional surveys were conducted among randomly selected children of this age group from the intervention area (HF+ComDT area) and the comparison area (HF area) at baseline (n=986), 12 months (n=796) and 18 months (n=788) follow-up. The prevalence of Ascaris lumbricoides was significantly higher in the HF+ComDT as compared to the HF area at baseline (P=0·048), but not at 12 and 18 months follow-up. At baseline the HF+ComDT area had significantly higher intensities of A. lumbricoides compared to the HF area (P<0·001), but not at 12 and 18 months follow-ups. Prevalence and intensity of hookworm did not differ significantly between treatment arms at any time. Analysis of trends showed a significant decrease in prevalence of A. lumbricoides and hookworm in the HF+ComDT area (P<0·001), of hookworm in the HF area (P<0·05), but not of A. lumbricoides in the HF area. It is concluded that the ComDT approach generally enhanced the treatment effect among under-five year children and that this alternative approach may also have advantages in other geographical settings.     

Predisposition to reinfection by intestinal helminths after chemotherapy in south Thailand.

Rates of reinfection by the intestinal helminths hookworm, Ascaris lumbricoides and Trichuris trichiura after chemotherapy were studied in two villages in Phang-Nga Province, southern Thailand. It was found that intensity of infection levels attained after reinfection correlated positively with pretreatment intensities of infection for all parasites. This implies that certain persons in the community are predisposed to receiving high numbers of worms, due either to environmental or personal risk factors. Therefore, it would be advantageous to identify such persons and treat them preferentially. Targeted chemotherapy, however, should be combined with efforts to identify the risk factors that vary within the community and direct educational efforts or environmental intervention towards the section of the community most affected by the parasites.     

Comparative study on the effectiveness of modified Kato's cellophane thick smear and Stoll's dilution egg counting technique for quantitative fecal examination of helminth eggs]

A total of 197 fecal specimens was prepared for quantitative examination of helminth eggs by modified Kato's cellophane thick smear (M.C.T.S.) and Stoll's dilution egg counting technique (D.E.C.T.). The comparative effectiveness of two techniques was evaluated and conversion function was deduced. The average time required for the microscopic examination on one slide by M.C.T.S. was 12.6 minutes and that of D.E.C.T. was 14.6 minutes. M.C.T.S. showed lower false negative rate than D.E.C.T. in light worm burden cases. Functions to convert the counts obtained by M.C.T.S. to E.P.G. by Stoll's dilution egg counting technique were 47.86 x 10(0.87) logM.C.T.S. in A. lumbricoides, 41.69 x 10(0.82) logM.C.T.S. in T. trichiura and 63.10 x 10(0.85) logM.C.T.S. in C. sinensis. It was suggested M.C.T.S. be better than D.E.C.T. for the quantitative examination of intestinal helminthiases such as A. lumbricoides, T. trichiura, and C. sinensis infections even in the cases with low worm burden.