Serious limitations of the current strategy to control Soil-Transmitted Helminths and added value of Ivermectin/Albendazole mass administration: A population-based observational study in Cameroon.

BACKGROUND: Soil-transmitted helminth (STH) infections remain a public health concern in sub-Saharan Africa. School-based mass drug administration (MDA) using the anthelminthic drug Mebendazole/Albendazole have succeeded in controlling morbidity associated to these diseases but failed to interrupt their transmission. In areas were filarial diseases are co-endemic, another anthelminthic drug (Ivermectin) is distributed to almost the entire population, following the community-directed treatment with ivermectin (CDTI) strategy. Since Ivermectin is a broad spectrum anthelmintic known to be effective against STH, we conducted cross-sectional surveys in two health districts with very contrasting histories of Ivermectin/Albendazole-based PC in order to investigate whether CDTI might have contributed in STH transmission interruption. METHODOLOGY: Cross-sectional surveys were conducted in two health districts with similar socio-environmental patterns but with very contrasting CDTI histories (Akonolinga health district where CDTI was yet to be implemented vs. Yabassi health district where CDTI has been ongoing for two decades). Stool samples were collected from all volunteers aged >2 years old and analyzed using the Kato-Katz technique. Infections by different STH species were compared between Akonolinga and Yabassi health districts to decipher the impact of Ivermectin/Albendazole-based MDA on STH transmission. PRINCIPAL FINDINGS: A total of 610 and 584 participants aged 2-90 years old were enrolled in Akonolinga and Yabassi health districts, respectively. Two STH species (Ascaris lumbricoides and Trichuris trichiura) were found, with prevalence significantly higher in Akonolinga health district (43.3%; 95% CI: 38.1-46.6) compared to Yabassi health district (2.5%; 95% CI: 1.1-5.1) (chi-square: 90.8; df: 1; p < 0.001). CONCLUSION/SIGNIFICANCE: These findings (i) suggest that Mebendazole- or Albendazole-based MDA alone distributed only to at-risk populations might not be enough to eliminate STH, (ii) support the collateral impact of Ivermectin/Albendazole MDA on A. lumbricoides and T. trichiura infections, and (iii) suggest that Ivermectin/Albendazole-based PC could accelerate STH transmission interruption.

Effects of nutritional supplements on the re-infection rate of soil-transmitted helminths in school-age children: A systematic review and meta-analysis.

BACKGROUND: The effect of nutritional supplements on the re-infection rate of species-specific soil-transmitted helminth infections in school-aged children remains complex and available evidence on the subject matter has not been synthesized. METHODS: The review included randomised controlled trials (RCTs) and cluster RCTs investigating food supplements on school-aged children between the age of 4-17 years. A search for RCTs was conducted on eight databases from inception to 12th June 2019. Cochrane Risk of Bias tool was used to assess the risk of bias in all included studies. Meta-analysis and narrative synthesis were conducted to describe and analyze the results of the review. Outcomes were summarized using the mean difference or standardized mean difference where appropriate. RESULTS: The search produced 1,816 records. Six studies met the inclusion criteria (five individually RCTs and one cluster RCT). Four studies reported data on all three STH species, while one study only reported data on Ascaris lumbricoides infections and the last study reported data on only hookworm infections. Overall, the risk of bias in four individual studies was low across most domains. Nutritional supplementation failed to statistically reduce the re-infection rates of the three STH species. The effect of nutritional supplements on measures of physical wellbeing in school-aged children could not be determined. CONCLUSIONS: The findings from this systematic review suggest that nutritional supplements for treatment of STH in children should not be encouraged unless better evidence emerges. Conclusion of earlier reviews on general populations may not necessarily apply to children since children possibly have a higher re-infection rate.

Sustained preventive chemotherapy for soil-transmitted helminthiases leads to reduction in prevalence and anthelminthic tablets required.

BACKGROUND: The goal of soil-transmitted helminthiases (STH) control programmes is to eliminate STH-associated morbidity in the target population by reducing the prevalence of moderate- and heavy-intensity infections and the overall STH infection prevalence mainly through preventive chemotherapy (PC) with either albendazole or mebendazole. Endemic countries should measure the success of their control programmes through regular epidemiological assessments. We evaluated changes in STH prevalence in countries that conducted effective PC coverage for STH to guide changes in the frequency of PC rounds and the number of tablets needed. METHODS: We selected countries from World Health Organization (WHO)'s Preventive Chemotherapy and Transmission control (PCT) databank that conducted ≥5 years of PC with effective coverage for school-age children (SAC) and extracted STH baseline and impact assessment data using the WHO Epidemiological Data Reporting Form, Ministry of Health reports and/or peer-reviewed publications. We used pooled and weighted means to plot the prevalence of infection with any STH and with each STH species at baseline and after ≥5 years of PC with effective coverage. Finally, using the WHO STH decision tree, we estimated the reduction in the number of tablets needed. RESULTS: Fifteen countries in four WHO regions conducted annual or semi-annual rounds of PC for STH for 5 years or more and collected data before and after interventions. At baseline, the pooled prevalence was 48.9% (33.1-64.7%) for any STH, 23.2% (13.7-32.7%) for Ascaris lumbricoides, 21.01% (9.7-32.3%) for Trichuris trichiura and 18.2% (10.9-25.5%) for hookworm infections, while after ≥5 years of PC for STH, the prevalence was 14.3% (7.3-21.3%) for any STH, 6.9% (1.3-12.5%) for A. lumbricoides, 5.3% (1.06-9.6%) for T. trichiura and 8.1% (4.0-12.2%) for hookworm infections. CONCLUSIONS: Countries endemic for STH have made tremendous progress in reducing STH-associated morbidity, but very few countries have data to demonstrate that progress. In this study, the data show that nine countries should adapt their PC strategies and the frequency of PC rounds to yield a 36% reduction in drug needs. The study also highlights the importance of impact assessment surveys to adapt control strategies according to STH prevalence.

Controlling Taenia solium and soil transmitted helminths in a northern Lao PDR village: Impact of a triple dose albendazole regime.

Taenia solium taeniasis-cysticercosis and soil-transmitted helminths (STHs) are parasitic Neglected Tropical Diseases endemic throughout Southeast Asia. Within Lao PDR, a remote northern hill tribe village had previously been identified as a hyper endemic focus for T. solium. To reduce this observed prevalence, a One Health intervention covering both pigs and humans was implemented, which included two Mass drug administrations (MDA1 and MDA2) for village residents using a triple dose albendazole 400mg treatment regime. In addition to the effect on T. solium levels, the dual impact of this anthelmintic regime on STHs within the community was also monitored. Faecal samples were collected pre and post MDA1 and MDA2 and analysed for the presence of Taenia species and the STHs Ascaris lumbricoides, Trichuris trichiura and hookworm species. The McMaster technique was used to measure the changes in both prevalence and intensity of infection. Molecular characterisation of Taenia and hookworm species was conducted to detect zoonotic species. The level of taeniasis within the sampled population decreased by 79.4% after MDA1, remained steady during the five month inter-treatment interval and decreased again by 100% after MDA2. The prevalence of STHs decreased by 65.5% and 62.8% after MDA1 and MDA2 respectively; however an increase to 62.1% of pre MDA1 levels was detected during the inter-treatment interval. Individually, hookworm prevalence decreased by 83.4% (MDA1) and 84.5% (MDA2), A. lumbricoides by 95.6% and 93.5% and T. trichiura by 69.2% and 61%. The intensity of infection within the sampled population also decreased, with egg reduction rates of 94.4% and 97.8% for hookworm, 99.4% and 99.3% for A. lumbricoides and 77.2% and 88.5% for T. trichiura. Molecular characterisation identified a T. solium tapeworm carrier from 21.6% (13/60) of households in the village. T. saginata was identified in 5% (3/60) of households. The zoonotic hookworm A. ceylanicum was detected in the resident dog population. These results suggest that the triple dose albendazole 400mg treatment regime achieved a significant reduction in the level of taeniasis whilst simultaneously reducing the STH burden within the village. The increased STH prevalence detected between MDAs reflects the need for behavioural changes and a sustained chemotherapy programme, which may also need to include the resident dog population.

Control of soil-transmitted helminthiasis in Yunnan province, People's Republic of China: experiences and lessons from a 5-year multi-intervention trial.

The current global strategy for the control of soil-transmitted helminthiasis emphasises periodic administration of anthelminthic drugs to at-risk populations. However, this approach fails to address the root social and ecological causes of soil-transmitted helminthiasis. For sustainable control, it has been suggested that improvements in water, sanitation and hygiene behaviour are required. We designed a 5-year multi-intervention trial in Menghai county, Yunnan province, People's Republic of China. Three different interventions were implemented, each covering a village inhabited by 200-350 people. The interventions consisted of (i) initial health education at study inception and systematic treatment of all individuals aged ≥2 years once every year with a single dose of albendazole; (ii) initial health education and bi-annual albendazole administration; and (iii) bi-annual treatment coupled with latrine construction at family level and regular health education. Interventions were rigorously implemented for 3 years, whilst the follow-up, which included annual albendazole distribution, lasted for 2 more years. Before the third round of treatment, the prevalence of Ascaris lumbricoides was reduced by only 2.8% in the annual treatment arm, whilst bi-annual deworming combined with latrine construction and health education resulted in a prevalence reduction of 53.3% (p<0.001). All three control approaches significantly reduced the prevalence of Trichuris trichiura and hookworm, with the highest reductions achieved when chemotherapy was combined with sanitation and health education. The prevalence of T. trichiura remained at 30% and above regardless of the intervention. Only bi-annual treatment combined with latrine construction and health education significantly impacted on the prevalence of Taenia spp., but none of the interventions significantly reduced the prevalence of Strongyloides stercoralis. Our findings support the notion that in high-endemicity areas, sustainable control of soil-transmitted helminth infections necessitates measures to reduce faecal environmental contamination to complement mass drug administration. However, elimination of soil-transmitted helminthiasis will not be achieved in the short run even with a package of interventions, and probably requires improvements in living conditions, changes in hygiene behaviour and more efficacious anthelminthic drugs and treatment regimens.

Soil-transmitted helminths in southern highland Rwanda: associated factors and effectiveness of school-based preventive chemotherapy.

OBJECTIVES: Preventive chemotherapy of schoolchildren against soil-transmitted helminths (STHs) is widely implemented in Rwanda. However, data on its actual efficacy are lacking. We assessed prevalence, associated factors and manifestation of STH infection among schoolchildren in southern highland Rwanda as well as cure and reinfection rates. METHODS: Six hundred and twenty-two children (rural, 301; urban, 321) were included preceding the administration of a single dose of 500 mg mebendazole. Before treatment, and after 2 and 15 weeks, STH infection was determined by Kato-Katz smears and by PCR assays for Ascaris lumbricoides. Clinical and anthropometric data, socio-economic status and factors potentially associated with STH infection were assessed. RESULTS: Soil-transmitted helminth (STH) infection was present in 38% of rural and in 13% of urban schoolchildren. Ascaris lumbricoides accounted for 96% of infections. Of these, one-third was detected by PCR exclusively. Factors associated with STH infection differed greatly between rural and urban children. Likewise, STH infection was associated with stunting and anaemia only among urban children. The cure rate after 2 weeks was 92%. Among eight non-cleared A. lumbricoides infections, seven were submicroscopic. Reinfection within 3 months occurred in 7%, but the rate was higher among rural children, and with initially present infection, particularly at comparatively high intensity. CONCLUSIONS: The rural-urban difference in factors associated with STH infection and in reinfection rates highlights the need for targeted interventions to reduce transmission. PCR assays may help in detecting low-level infections persisting after treatment. In southern Rwanda, mebendazole is highly effective against the STH infections predominated by A. lumbricoides.

Trichuris and hookworm infections associated with anaemia during pregnancy.

OBJECTIVE: To assess the following associations between the second and third trimesters of pregnancy: (i) the intensity of soil-transmitted helminth (STH) infection and haemoglobin/anaemia, (ii) the effect of mebendazole treatment on the occurrence of STH infection, and (iii) the effect of mebendazole treatment on haemoglobin/anaemia. METHODS: Data originated from a trial of 1042 pregnant women recruited in their second trimester and followed to delivery. Baseline assessments included socio-demographic/health information from questionnaires, haemoglobin/anaemia from HemoCue ascertainment of fingerprick blood, and the presence and intensity of STH (Ascaris lumbricoides, hookworms and Trichuris trichiura) infections from Kato-Katz examination. All women were given iron supplements; half were randomly allocated to receive single dose 500 mg mebendazole, and half, placebo. Haemoglobin/anaemia and STH infection status were determined again in the third trimester of pregnancy. RESULTS: Complete information was available from 935 (89.7%) women. Mebendazole significantly reduced the prevalence and intensity of all three STH infections. Higher intensities of hookworm and Trichuris infections in the second trimester were associated with a higher risk of anaemia in the third trimester. Overall, women with moderate/heavy Trichuris infection were found to be at a higher risk of anaemia; the highest risk was observed among those with moderate/heavy hookworm co-infection (adjusted OR = 2.77; 95% CI: 1.26, 6.11). Mebendazole treatment did not reduce the risk of anaemia. CONCLUSION: Higher intensities of both Trichuris and hookworm infections are associated with anaemia in pregnancy. The importance of Trichuris infections during pregnancy requires renewed attention.

Spatial co-distribution of neglected tropical diseases in the east African great lakes region: revisiting the justification for integrated control.

OBJECTIVE: To determine spatial patterns of co-endemicity of schistosomiasis mansoni and the soil-transmitted helminths (STHs) Ascaris lumbricoides, Trichuris trichiura and hookworm in the Great Lakes region of East Africa, to help plan integrated neglected tropical disease programmes in this region. METHOD: Parasitological surveys were conducted in Uganda, Tanzania, Kenya and Burundi in 28 213 children in 404 schools. Bayesian geostatistical models were used to interpolate prevalence of these infections across the study area. Interpolated prevalence maps were overlaid to determine areas of co-endemicity. RESULTS: In the Great Lakes region, prevalence was 18.1% for Schistosoma mansoni, 50.0% for hookworm, 6.8% for A. lumbricoides and 6.8% for T. trichiura. Hookworm infection was ubiquitous, whereas S. mansoni, A. lumbricoides and T. trichiura were highly focal. Most areas were endemic (prevalence >or=10%) or hyperendemic (prevalence >or=50%) for one or more STHs, whereas endemic areas for schistosomiasis mansoni were restricted to foci adjacent large perennial water bodies. CONCLUSION: Because of the ubiquity of hookworm, treatment programmes are required for STH throughout the region but efficient schistosomiasis control should only be targeted at limited high-risk areas. Therefore, integration of schistosomiasis with STH control is only indicated in limited foci in East Africa.

The effect of iron and multi-micronutrient supplementation on Ascaris lumbricoides reinfection among Zambian schoolchildren.

A randomised, placebo-controlled, double-blind trial was conducted among schoolchildren in Chawama, Lusaka, Zambia, to determine the effect of iron and multi-micronutrients on reinfection with Ascaris lumbricoides. Supplementation was given on every school day for 10 months. Baseline A. lumbricoides prevalence and geometric mean intensity among positives were 43.4% and 2526 eggs per gram (epg) faeces, respectively. Serum ferritin <12microg/l was associated with higher egg counts than serum ferritin >or=12microg/l (4728 vs. 2036epg, P=0.033). Of 406 children recruited, 378 (93.1%) were examined at baseline and all infected children were treated and cure ascertained. The mean number of tablets taken per week was 2.5, giving 50% compliance. At six months 283 (74.9%) children complied, and reinfection intensities in those receiving iron were lower than in those receiving placebo (1600 vs. 3085epg, P=0.056). This effect disappeared at 10 months, where 215 (56.9%) complied. Iron had no effect on A. lumbricoides reinfection rates and multi-micronutrients had no effect on reinfection rates or intensities. Iron appears to affect reinfection intensity with A. lumbricoides, but further investigations are required to confirm this effect and elucidate the mechanisms involved.

Impact of long-term treatment with ivermectin on the prevalence and intensity of soil-transmitted helminth infections.

BACKGROUND: Control of soil-transmitted helminth (STH) infections relies on the periodic and long-term administration of anthelmintic drugs to high-risk groups, particularly school-age children living in endemic areas. There is limited data on the effectiveness of long-term periodic anthelmintic treatment on the prevalence of STHs, particularly from operational programmes. The current study investigated the impact of 15 to 17 years of treatment with the broad-spectrum anthelmintic ivermectin, used for the control of onchocerciasis, on STH prevalence and intensity in school-age and pre-school children. METHODS AND FINDINGS: A cross-sectional study was conducted in communities that had received annual or twice-annual ivermectin treatments and geographically adjacent communities that had not received treatment in two districts of Esmeraldas Province in Ecuador. Stool samples were collected from school-age children and examined for STH infection using the Kato-Katz and formol-ether concentration methods. Samples were collected also from pre-school children and examined by the formol-ether concentration method. Data on risk factors for STH infection were collected by parental questionnaire. We sampled a total of 3,705 school-age children (6-16 years) from 31 treated and 27 non-treated communities, and 1,701 pre-school children aged 0-5 years from 18 treated and 18 non-treated communities. Among school-age children, ivermectin treatment had significant effects on the prevalence (adjusted OR = 0.06, 95% CI 0.03-0.14) and intensity of Trichuris trichiura infection (adjusted RR = 0.28, 95% CI 0.11-0.70), but appeared to have no impact on Ascaris lumbricoides or hookworm infection. Reduced prevalence and intensities of T. trichiura infection were observed among children not eligible to receive ivermectina, providing some evidence of reduced transmission of T. trichiura infection in communities receiving mass ivermectin treatments. CONCLUSION: Annual and twice-annual treatments with ivermectin over a period of up to 17 years may have had a significant impact on T. trichiura infection. The present data indicate that the long-term control of onchocerciasis with ivermectin may provide additional health benefits by reducing infections with trichuriasis. The addition of a second anthelmintic drug such as albendazole may be useful for a long-term effect on A. lumbricoides infection.

Hygiene versus fertiliser: the use of human excreta in agriculture--a Vietnamese example.

The use of human excreta as fertiliser in agriculture is a common practice in parts of South East Asia benefiting production but at the same time a risk factor for increased helminth infections. This paper describes the hygienic handling of human excreta for use in agriculture in Central Vietnam from a practical farming perspective presenting the farmers perceived health risks and benefits of its use. Further, in the study findings are discussed relating to the new Vietnamese guidelines for the use of human excreta in agriculture to their implications on an on-farm context. A total of 471 households in five communes responded to a structured questionnaire. This survey was supplemented by focus group discussions, key informant interviews and participant observations. More than 90% of the surveyed households used their own excreta as fertiliser and a total of 94% composted the excreta before use, either inside or outside the latrine. However, due to the prevailing design of the latrine and the three annual cropping seasons, it was found that for a minimum of one cultivation season per year 74% of the households will have only 3-4 months for composting before the input is needed in production, which is short of the 6 months stipulated in the national guidelines. The community associated great benefits from using human excreta in agriculture, especially if composted, and did not associate risks with the use of composted excreta if it was dry and lacked odour. It is recommended that the guidelines be revised and attempts made to identify ways of reducing the time needed to ensure the die-off of helminth eggs, including the use of pH regulators, such as an increased use of lime in the latrines.

Benefit of vitamin A supplementation on ascaris reinfection is less evident in stunted children.

Despite the common coexistence of vitamin A deficiency and Ascaris infection in preschool children in developing countries, and despite the widespread use of vitamin A supplements, remarkably little is understood about the impact of vitamin A supplementation on this gastrointestinal nematode. The Ministry of Health of Panama recently initiated a vitamin A supplementation program in rural indigenous populations. We took advantage of this initiative to assess the benefit of 200,000 IU (60 mg retinol) vitamin A on reinfection with Ascaris following deworming. Baseline stool exams, anthropometry, and socio-economic data were collected for 328 preschool children from 12-60 mo of age (106 supplemented within previous 3 mo and 222 unsupplemented within previous 6 mo). All children were dewormed with albendazole, and reinfection levels were monitored 3 and 5 mo later. Baseline prevalence of Ascaris was 79.5%. Stepwise regression showed that Ascaris intensity was lower in Vit A-supplemented children at baseline and 3 mo after deworming, but not after 5 mo. As 61% of the children were stunted, the impact of supplementation on Ascaris reinfection was examined separately for stunted and children of normal height. Prevalence and intensity of Ascaris at baseline and 3 mo after deworming were lower in children of normal height, but in stunted children the benefit was restricted to those who were dewormed within 6 wk of supplementation. Our study provides evidence that combined vitamin A supplementation and deworming reduces Ascaris reinfection in children living in areas of chronic parasitosis, but that the duration of the benefit is less in stunted children.

The effect of iron fortification and de-worming on anaemia and iron status of Vietnamese schoolchildren.

Previous data from Vietnam show that anaemia is highly prevalent among schoolchildren, who are considered not to be iron deficient. Trichuris infection doubled the risk of anaemia. The present study aimed to evaluate the hypothesis that de-worming is more effective than iron fortification in an anaemic, infection-prone population. In a trial with a 2 x 2 factorial design, 425 anaemic children aged 6-8 years were randomly assigned to receive either iron-fortified noodles or placebo, and mebendazole or placebo. Outcomes considered were change in haematological indicators of iron status (Hb, serum ferritin (SF), serum transferrin receptor (TfR) and haemoglobinopathies analysis); inflammations (C-reactive protein (CRP)); parasite infection status (hookworm, Trichuris and Ascaris infection); and IgE. ANOVA and logistic regression were used to assess the effects of iron fortification and de-worming on Hb, SF, TfR, body iron and anaemia. Hb improved in all groups after 6 months of intervention. Iron fortification significantly improved Hb, SF and body iron (2.6 g/l, 16.3 microg/l and 1 mg/kg, respectively). Prevalence of elevated IgE was very high at baseline (99%) and significantly reduced to about 75% in all groups after intervention. De-worming unexpectedly showed no effect on Hb, iron status and IgE level. It is concluded that iron fortification slightly improved anaemia and iron status in anaemic schoolchildren in rural Vietnam that were not considered iron deficient. Chronic infection or other unidentified factors may play an important role in the seasonal reduction of anaemia seen in all treatment groups.

Instruction in behavior modification can significantly alter soil-transmitted helminth (STH) re-infection following therapeutic de-worming.

Five elementary ("prototypic") schools located in five districts in central Java were selected and the children examined for helminth infections (Ascaris, Trichuris, hookworm). They were de-wormed with a course of mebendazole and provided with 6-7 months of "behavioral remediation instruction" (BRI). In other ("control") schools, children were treated with mebendazole but were not provided BRI. The objective was to determine the effectiveness of BRI in minimizing infection/re-infection following deworming. After the 6-7 month course of BRI in the prototypic schools, all the children (in both the prototypic and control schools) were re-examined for geohelminth infection. The schools in two of the five districts were omitted from further analysis because the overall prevalence of infection was low (<10%) and the infections were dominated by hookworm which are only moderately susceptible to mebendazole. Comparisons of prototypic and control schools in the other three districts provided compelling evidence that BRI was quite effective in reducing both the frequency and intensity of infection with Ascaris and Trichuris. We suggest that instructing children and adults corrects personal habits which are conducive to infection and can be an effective and safe substitute for repeated deworming, reducing the opportunity for the emergence of drug-resistant helminthes, which should prolong the time benzimidazoles may be used for treatment of geohelminth infection.

The impact of iron supplementation on reinfection with intestinal helminths and Schistosoma mansoni in western Kenya.

A randomized, placebo-controlled, double-blind trial was carried out in 1994-96 among 231 children and 181 adults in order to determine the effects of iron on reinfection rates and intensities of hookworm, Ascaris lumbricoides, Trichuris trichiura and Schistosoma mansoni. Adults given 60 mg elemental iron twice-weekly for 12 months had significantly lower reinfection rates of A. lumbricoides (16.7% vs 31.9%, P = 0.046), T. trichiura (6.9% vs 20.6%, P = 0.03) and S. mansoni (38.3% vs 61.8%, P = 0.008) compared to adults given placebo. In contrast, adults allocated to iron had a significantly higher reinfection rate of hookworm at the 4-month examination (11.1% vs 0%, P = 0.009), but the difference was not significant at 8- and 12-month follow-up examinations. Iron supplementation had no effect on reinfection intensities in adults. Surprisingly, iron supplementation had no effect on either reinfection rates or intensities in children. Multiple logistic regression analyses controlling for baseline infection status confirmed the effect in adults of iron on A. lumbricoides, T. trichiura and S. mansoni reinfection rates. The effect is suggested to be due to reduced risk behaviour, to improved immune function or to unfavourable host gut conditions caused by an increased oxidative stress. In each case, the lack of effect in children remains to be explained. In contrast, iron supplementation apparently was short-lived in favour of hookworm infection, an effect that needs further clarification. The findings suggest that iron supplementation has a role to play in helminth control programmes and that intraluminal factors may contribute to the regulation of some helminth infections.

Effect of papaya latex against Ascaris suum in naturally infected pigs.

An experiment was carried out to investigate the anthelmintic activity of papaya latex (Carica papaya) against natural infection of Ascaris suum in pigs. Sixteen naturally infected pigs were, on the basis of faecal egg counts and body weight, allocated into four groups, each of four pigs. Three groups (groups B, C, and D) were given papaya latex per os at dose levels of 2, 4, and 8 g of papaya latex per kg body weight, respectively. The fourth group (group A) served as a non-treated control. Results of post mortem counts on day 7 post treatment revealed worm count reductions of 39.5, 80.1 and 100% in groups B, C, and D, respectively. Some of the pigs receiving the highest dose of the latex showed mild diarrhoea on the day following treatment. Otherwise, no clinical or pathological changes were observed in the treated animals. The possible future use of this traditional herbal medicine for livestock and humans is discussed.

[Experiences with ivermectin in exotic animals: scabies in camelids (Camelus bactrianus, Lama guanicoe, L. glama) and scabies and roundworms in bears (Thalarctos maritimus and Ursus arctos)]. / Erfahrungen mit Ivermectin bei exotischen Tieren: Räude bei Kameliden (Camelus bactrianus, Lama guanicoe, L. glama) sowie Räude und Spulwurmbefall bei Bären (Thalarctos maritimus und Ursus arctos).

For the control of scabies in tylopodes (L. bactrianus, L. guanicoe, L. glama) and brown bears 0.2 mg/kg body weight (1 ml/50 kg body weight) of Ivermectin subcutaneously injected proved to be remedy of choice. In Kodiak-bears the oral application of Ivomec-solution was effective against ascariasis, not, however, in polar bears. Sufficient effect was reached only once, whereas Equalan-paste proved to be highly effective. Despite of strong hygienic measures continous follow-up treatment for the prevention of re-invasion is indispensible.

Preclinical and clinical studies with latex from Ficus glabrata HBK, a traditional intestinal anthelminthic in the Amazonian area.

Ficus glabrata latex has been a well-known anthelminthic remedy in the neotropical regions since ancient times. The latex has been commercially exploited for decades because of its content of the proteolytic enzyme-complex ficin. A safe dosage regimen with direct use of the latex has been elucidated to control intestinal helminthiasis in the Indian and non-Indian rural population. Helminthiasis was common in three Amazonian villages, field bases for the clinical study, with an overall prevalence of 92%. Specific prevalences were: Ascaris 68%, Strongyloides 42%, Trichuris 41%, Ancylostoma/Necator 26% and Taenia 1%. Variation in the biological activity of the latex was estimated by using a milk coagulating test. Pharmacological studies with live Ascaris demonstrated a lethal effect at concentrations down to 0.05% latex in physiological saline solution. A clinical trial on 181 persons has resulted in a recommended dosage of 1.0 cm3 of prepared latex/kg per day for 3 days to be repeated every 3 months.

Effect of periodic antiascaris and antigiardia treatment on nutritional status of preschool children.

One hundred fifty-nine children aged 24 to 61 months with 60% ascariasis prevalence and 21.5% giardiasis prevalence in rural Guatemala were studied prospectively for 1 yr. They were divided into four groups comparable for age, sex, socioeconomic status, and past growth experience as judged by slopes of height and weight on age. Each group was randomly assigned to the following 2-monthly treatment regimens: group I, placebo, group II, piperazine, group III, metronidazole; group IV, piperazine and metronidazole. Height and weight were measured every 3 months and stools were examined for parasites every 4 months. Piperazine administration decreased the prevalence of ascariasis to 33.8% at the end of the study but growth remained unaltered. Metronidazole administration decreased the prevalence of giardiasis to 2.5% at the end of the study and was accompanied by increased growth as judged by delta weight, delta % weight for age, slope of weight on age, delta height, delta % height for age and slope of height on age. It is suggested that failure of antiascaris treatment to enhance growth in this study may be because of 1) absence of severe malnutrition in the subjects, 2) adequacy of dietary protein, 3) possible low worm load, and 4) failure to eradicate ascariasis. The findings suggest that giardiasis is associated with reduced growth in preschool children.