Unusual presentations of a severe type 2 leprosy reaction mimicking sepsis induced by helminth infection

We describe an unusual case of type 2 leprosy reaction (T2R) with septic shock–like features induced by helminth infection in a 31-year-old Moluccan male patient with a history of completed treatment of WHO multidrug therapy (MDT)–multibacillary (MB) regimen 2 years before admission. During the course of illness, the patient had numerous complications, including septic shock, anemia, and disseminated intravascular coagulation (DIC). Nevertheless, antibiotic therapies failed to give significant results, and the source of infection could not be identified. Helminth infection was subsequently revealed by endoscopic examination followed by parasitological culture. Resolution of symptoms and normal level of organ function–specific markers were resolved within 3 days following anthelmintic treatment. This report demonstrated the challenge in the diagnosis and treatment of severe T2R. Given that helminth infections may trigger severe T2R that mimics septic shock, health professionals need to be aware of this clinical presentation, especially in endemic regions of both diseases.

Immunity to Soil-Transmitted Helminths: Evidence From the Field and Laboratory Models

Infection with soil-transmitted helminths (STH) remains a major burden on global health and agriculture. Our understanding of the immunological mechanisms that govern whether an individual is resistant or susceptible to infection is derived primarily from model infections in rodents. Typically, experimental infections employ an artificially high, single bolus of parasites that leads to rapid expulsion of the primary infection and robust immunity to subsequent challenges. However, immunity in natura is generated slowly, and is only partially effective, with individuals in endemic areas retaining low-level infections throughout their lives. Therefore, there is a gap between traditional model STH systems and observations in the field. Here, we review the immune response to traditional model STH infections in the laboratory. We compare these data to studies of natural infection in humans and rodents in endemic areas, highlighting crucial differences between experimental and natural infection. We then detail the literature to date on the use of "trickle" infections to experimentally model the kinetics of natural infection.

Soil transmitted helminthiasis in indigenous groups. A community cross sectional study in the Amazonian southern border region of Ecuador

BACKGROUND

Rural communities in the Amazonian southern border of Ecuador have benefited from governmental social programmes over the past 9 years, which have addressed, among other things, diseases associated with poverty, such as soil transmitted helminth infections. The aim of this study was to explore the prevalence of geohelminth infection and several factors associated with it in these communities.

METHODS

This was a cross sectional study in two indigenous communities of the Amazonian southern border of Ecuador. The data were analysed at both the household and individual levels.

RESULTS

At the individual level, the prevalence of geohelminth infection reached 46.9% (95% CI 39.5% to 54.2%), with no differences in terms of gender, age, temporary migration movements or previous chemoprophylaxis. In 72.9% of households, one or more members were infected. Receiving subsidies and overcrowding were associated with the presence of helminths.

CONCLUSIONS

The prevalence of geohelminth infection was high. Our study suggests that it is necessary to conduct studies focusing on communities, and not simply on captive groups, such as schoolchildren, with the object of proposing more suitable and effective strategies to control this problem.

Population Density, Poor Sanitation, and Enteric Infections in Nueva Santa Rosa, Guatemala

Poor sanitation could pose greater risk for enteric pathogen transmission at higher human population densities because of greater potential for pathogens to infect new hosts through environmentally mediated and person-to-person transmission. We hypothesized that incidence and prevalence of diarrhea, enteric protozoans, and soil-transmitted helminth infections would be higher in high-population-density areas compared with low-population-density areas, and that poor sanitation would pose greater risk for these enteric infections at high density compared with low density. We tested our hypotheses using 6 years of clinic-based diarrhea surveillance (2007–2013) including 4,360 geolocated diarrhea cases tested for 13 pathogens and a 2010 cross-sectional survey that measured environmental exposures from 204 households (920 people) and tested 701 stool specimens for enteric parasites. We found that population density was not a key determinant of enteric infection nor a strong effect modifier of risk posed by poor household sanitation in this setting.

The epidemiology of soil-transmitted helminths in Bihar State, India

BACKGROUND

Soil-transmitted helminths (STHs) infect over a billion individuals worldwide. In India, 241 million children are estimated to need deworming to avert the negative consequences STH infections can have on child health and development. In February-April 2011, 17 million children in Bihar State were dewormed during a government-led school-based deworming campaign. Prior to programme implementation, a study was conducted to assess STH prevalence in the school-age population to direct the programme. The study also investigated risk factors for STH infections, including caste, literacy, and defecation and hygiene practices, in order to inform the development of complementary interventions.

METHODS

A cross-sectional survey was conducted among children in 20 schools in Bihar. In addition to providing stool samples for identification of STH infections, children completed a short questionnaire detailing their usual defecation and hand-hygiene practices. Risk factors for STH infections were explored.

RESULTS

In January-February 2011, 1279 school children aged four to seventeen provided stool samples and 1157 children also completed the questionnaire. Overall, 68% of children (10-86% across schools) were infected with one or more soil-transmitted helminth species. The prevalence of ascariasis, hookworm and trichuriasis was 52%, 42% and 5% respectively. The majority of children (95%) practiced open defecation and reported most frequently cleansing hands with soil (61%). Increasing age, lack of maternal literacy and certain castes were independently associated with hookworm infection. Absence of a hand-washing station at the schools was also independently associated with A. lumbricoides infection.

CONCLUSIONS

STH prevalence in Bihar is high, and justifies mass deworming in school-aged children. Open defecation is common-place and hands are often cleansed using soil. The findings reported here can be used to help direct messaging appropriate to mothers with low levels of literacy and emphasise the importance of water and sanitation in the control of helminths and other diseases.

Knowledge, attitudes and practices among parents and teachers about soil-transmitted helminthiasis control programs for school children in Guimaras, Philippines

We determined the attitudes toward and practices regarding soil-transmitted helminthes (STH) control among parents and school teachers to identify reasons behind attitudes and practices that do not promote STH control. Written knowledge, attitudes and practices surveys were distributed to parents (N = 531) and teachers (N = 105) of students at 11 elementary schools in Guimaras Province, the Philippines. The survey addressed attitudes about mass drug administration (MDA), knowledge about STH control, hygienic practices, and acceptability of distributing deworming tablets among teachers. More than 90% of parents and teachers held favorable attitudes towards MDA. Sixty-nine percent of parents and 75.5% of teachers believed stool exams were necessary before MDA. Thirty-seven percent of parents stated they would not allow teachers to administer deworming tablets and 91.5% of parents feared teachers would not detect side effects of the medication. Forty-eight percent of teachers felt they could safely give deworming tablets and 81.4% of teachers were afraid of managing the side effects of deworming tablets. Forty-seven point eight percent of parents and 42.2% of teachers stated defecation in the open occured in their community. Although attitudes toward STH control were largely favorable, misconceptions about the MDA strategy, lack of support for teachers giving deworming tablets, and the practice of open defecation still exist as barriers to STH control efforts. The next step to achieve effective STH control will be to clarify misconceptions in education campaigns, to train teachers about medication administration, campaign to improve sanitation and hygiene and begin targeted mass treatment in Guimaras, the Philippines.

Assessment of a school-based mass treatment for soil-transmitted helminth infections in Capiz, the Philippines

We evaluated the War on Worms in the Western Visayas (WOW-V) school-based mass treatment strategy in Capiz, the Philippines by assessing potential determinants of program acceptance among parents, teachers, and local health and education officials involved. Written surveys were distributed to parents and teachers assessing knowledge, attitudes and practices regarding soil-transmitted helminth (STH) infections. Associations between data were examined using the Fisher's exact test (alpha = 0.05). Descriptive statistics and t-tests were employed to analyze teacher survey results. Local health and education officials participated in key-informant interviews (KIs) to evaluate their attitudes and practices regarding WOW-V; data was qualitatively analyzed and grouped. A strong association was observed between parental consent during the first two rounds of treatment and willingness to do so again. Most parents gave consent for their child to receive treatment at least once and demonstrated a high level of knowledge regarding STH infections. The majority of teachers had positive attitudes toward their role in the program. Many identified lack of training and a fear of side effects as barriers to higher coverage. Lack of funding, program monitoring difficulties and insufficient parental education were identified by local officials as barriers. Proper planning and design is important to achieve high initial consent for program acceptance. The results correlate with studies showing relationships between health education and treatment acceptance. The implementation of health education and monitoring measures has the potential to greatly improve both treatment coverage and program infrastructure.

Intestinal parasitic infections in Srimum suburban area of Nakhon Ratchasima Province, Thailand

A survey on intestinal parasitic infections and some risk factors of infection (social, economic and behavioral) was conducted in suburban area at Simum subdistrict, Mueang district, Nakhon Ratchasima Province during the period of April 3rd to April 11th, 2007. A total of 214 stool samples, from 85 males and 129 females were examined using simple direct smear, Kato's thick smear and modified Harada-Mori Filter Paper Strip culture technique. The results showed that the prevalence rate of protozoa infections by simple direct smear method was 17.3% (37 infected samples) in 11 males and 26 females and were from all age groups. Mixed infections (56.8%), showed higher results than single infection. The highest number of intestinal protozoan infections was Entamoeba histolytica (11.7%), followed by Blastocystis hominis (5.6%). Fifty four percent of protozoan infection was at a moderate to high level. Ninety five percent of infected cases consumed unboiled water. The prevalence rate of helminthic infections was 7% total by Kato's thick smear and Modified Harada-Mori Filter Paper Strip culture technique. Kato's Thick smear Technique showed the highest rate of Strongyloides stercolaris (2.8%), followed by hookworm infection (1.4%) Taenia spp. (0.9%), and Enterobius vermicularis (0.5%), respectively. All infections showed a light intensity, (< 200 epg), using Kato-Katz thick smear. Although Modified Harada-Mori's culture Technique showed higher S. stercolaris (3.3%) and hookworm infection (2.3%) than Kato's thick smear in the area where there is low Soil transmitted helminthes, we recommend using Simple or Kato's thick smear to determine the prevalence of parasitic infection due to these techniques being able to detect various groups of parasites, and being inexpensive and less time consuming.

[Examination of helminth contaminated wastewaters used for agricultural purposes in Afyonkarahisar]

This research was performed in order to examine helminth contaminated wastewaters used in agriculture in Afyonkarahisar. Ten rural areas were selected that used water for agricultural purposes from a creek contaminated with human and animal wastes. Between September 2004 and August 2005, these areas were visited once every two weeks, and a total of 240 water samples were collected. Out of untreated water samples, 32 samples (26.70%) had helminth eggs, whereas there were neither helminths nor developmental stages of helminths (p < 0.001) in treated water samples. Cestode eggs were seen in 10.00% of untreated water samples and nematode eggs were seen in 16.70%. Out of the helminth eggs, 13 (40.60%) were hookworm eggs; 6 (18.75%), Taenia spp.; 5 (5.60%), Ascaris lumbricoides; 3 (9.40%), Hymenolepis diminuta; 3 (9.40%), H. nana; and 2 (6.25%), Toxocara spp. In conclusion; the creek was found to be contaminated by helminths originating from human and animal wastes in Afyonkarahisar. This type of water presents a risk for human and animal health and contaminated waters, therefore, should be avoided in irrigation of vegetables and fruit consumed raw.

HIV and helminth co-infection: is deworming necessary?

We have previously suggested that helminth infections play a major role in the pathogenesis of HIV-1 infection in Africa and other developing areas, due to their profound effects on the host immune system, which make those infected more susceptible to HIV-1 infection and less able to cope with it. Chronic immune activation with a dominant Th2 profile, and anergy, are the hallmarks of chronic helminth infection, and may therefore account for most of these effects. In the present review, we summarize the studies that have addressed these issues and argue that despite some conflicting results, the cumulative immunological and epidemiological evidence is in favour of deworming as a preventive and possible therapeutic measure vis-à-vis HIV-1 infection. We suggest that it should be at least tested on a wider and larger scale than has been done until now, because of its immense potential impact on the still raging AIDS epidemic in developing countries.

Community's willingness to pay for a school-based chemotherapy programme to control morbidity due to schistosomiasis and soil-transmitted helminthiasis in children in rural Tanzania

A cross-sectional questionnaire survey was conducted on a random sample of 523 households having at least one child attending primary school in 3 villages in Buchosa Division, Sengerema District, Tanzania. The aim was to determine the community's willingness to pay (WTP) for a school-based chemotherapy programme to control morbidity due to schistosomiasis and soil-transmitted helminthiasis (STH) in schoolchildren and identify socio-economic and cultural factors influencing community's WTP. Results showed that households WTP for a school-based chemotherapy programme varied from Tanzanian Shillings (TShs.) 0-20,000 (US dollars 0-25) per child per year. The community's WTP (median of households WTP) was TSh. 1,000 (US dollars 1.25). The community was also willing to pay extra TSh.100 (US dollars 0.125) per year to cover for the cost of schoolchildren whose parents were unable to pay or who could pay less than the community's WTP. Age of household head and number of schoolchildren in a household had a negative effect on the household's willingness to pay. Households with children in expensive schools had high willingness to pay for the intervention package to control worms in their children. This was also observed in households keeping animals (cattle, goats, sheep, chiken, ducks) and those who cultivated a number of cash crops.

The role of helminth infections in protection from atopic disorders

PURPOSE OF REVIEW

The observation that allergies are less prevalent in developing countries, especially in rural areas, has stimulated considerable research to identify environmental factors associated with protection against allergic disorders. Here, we review recent studies conducted in developing countries.

RECENT FINDINGS

Epidemiological studies conducted in South America, Asia and Africa have attempted to identify factors associated with differences in prevalence of atopy, asthma and atopic dermatitis. Particular attention is given to the complex relationship between helminth infections and allergies. In answer to the question of whether helminth infections are associated with protection against allergic disorders, conflicting data have been generated. In addition to epidemiological studies, animal models have been utilized to gain insight into the immunological mechanisms involved in the interaction between helminth infections and allergies. These animal studies are discussed. The possible explanations for discrepancies found within both human and murine studies have been considered, highlighting the need for further research.

SUMMARY

An in-depth understanding of the relevant protective mechanisms against allergic disorders will open the possibility of developing novel therapeutics to prevent the allergic march worldwide.

Earth-eating and reinfection with intestinal helminths among pregnant and lactating women in western Kenya

We conducted a longitudinal study among 827 pregnant women in Nyanza Province, western Kenya, to determine the effect of earth-eating on geohelminth reinfection after treatment. The women were recruited at a gestational age of 14-24 weeks (median: 17) and followed up to 6 months postpartum. The median age was 23 (range: 14-47) years, the median parity 2 (range: 0-11). After deworming with mebendazole (500 mg, single dose) of those found infected at 32 weeks gestation, 700 women were uninfected with Ascaris lumbricoides, 670 with Trichuris trichiura and 479 with hookworm. At delivery, 11.2%, 4.6% and 3.8% of these women were reinfected with hookworm, T. trichiura and A. lumbricoides respectively. The reinfection rate for hookworm was 14.8%, for T. trichiura 6.65, and for A. lumbricoides 5.2% at 3 months postpartum, and 16.0, 5.9 and 9.4% at 6 months postpartum. There was a significant difference in hookworm intensity at delivery between geophagous and non-geophagous women (P=0.03). Women who ate termite mound earth were more often and more intensely infected with hookworm at delivery than those eating other types of earth (P=0.07 and P=0.02 respectively). There were significant differences in the prevalence of A. lumbricoides between geophagous and non-geophagous women at 3 (P=0.001) and at 6 months postpartum (P=0.001). Women who ate termite mound earth had a higher prevalence of A. lumbricoides, compared with those eating other kinds of earth, at delivery (P=0.02), 3 months postpartum (P=0.001) and at 6 months postpartum (P=0.001). The intensity of infections with T. trichiura at 6 months postpartum was significantly different between geophagous and non-geophagous women (P=0.005). Our study shows that geophagy is associated with A. lumbricoides reinfection among pregnant and lactating women and that intensities built up more rapidly among geophagous women. Geophagy might be associated with reinfection with hookworm and T. trichiura, although these results were less unequivocal. These findings call for increased emphasis, in antenatal care, on the potential risks of earth-eating, and for deworming of women after delivery.

Chronic immune activation associated with chronic helminthic and human immunodeficiency virus infections: role of hyporesponsiveness and anergy

Chronic immune activation is one of the hallmarks of human immunodeficiency virus (HIV) infection. It is present also, with very similar characteristics, in very large human populations infested with helminthic infections. We have tried to review the studies addressing the changes in the immune profiles and responses of hosts infected with either one of these two chronic infections. Not surprisingly, several of the immune derangements and impairments seen in HIV infection, and considered by many to be the "specific" effects of HIV, can be found in helminth-infected but HIV-noninfected individuals and can thus be accounted for by the chronic immune activation itself. A less appreciated element in chronic immune activation is the immune suppression and anergy which it may generate. Both HIV and helminth infections represent this aspect in a very wide and illustrative way. Different degrees of anergy and immune hyporesponsiveness are present in these infections and probably have far-reaching effects on the ability of the host to cope with these and other infections. Furthermore, they may have important practical implications, especially with regard to protective vaccinations against AIDS, for populations chronically infected with helminths and therefore widely anergic. The current knowledge of the mechanisms responsible for the generation of anergy by chronic immune activation is thoroughly reviewed.

Interactions between worm infections and malaria

Helminths are the most prevalent parasitic infections and malaria is the deadliest parasitic disease. Helminths have been reported to be protective against the severe forms of malaria but they were also possibly linked to increased malaria-incidence and gametocyte carriage. Connecting the dots between observations suggests that statistical regularities throughout the evolution of worms and malaria parasites in the same hosts, may have led to the emergence of non-zero interactions as observed in iterated prisoners dilemma games. Thus by protecting the host, helminths protect themselves and their reproductive potential, but also favor the dissemination and reproduction of Plasmodium falciparum. The proximate causes of this evolutionarily stable strategy might be mediated by IgE and the CD23/NO pathway, the protective role of IL10 in helminth-infected patients, and possibly the hematological consequences of worms. The chronic activation of the CD23/NO pathway might be instrumental in downregulating the expression of cytoadherence receptors thus reducing sequestration of parasitized red blood cells in the deep organs. Mild anemia in helminth-infected patients might favor gametocytogenesis and send attractive cues to the vector. This framework leads to numerous testable hypotheses and could explain certain singularities regarding the double edged role of IgE and NO. Among these hypotheses, there are 2 practical ones: the impact of helminths on malaria vaccine candidates, and the theoretical risk of increasing the severity of malaria after anthelmintics. The capacity for increased IgE responses could thus have been vital in our ancestor's wormy and malarious past. Allergies may be what remains of it in the modern world.

[Intestinal helminthiasis among school children: preliminary results of a prospective study in Agboville in Southern Côte d'Ivoire]

Intestinal helminthiasis affects the health and academic performance of children in developing countries. To highlight a few socio-economic factors that impact the presence and upholding of intestinal helminthiasis, a cohort study was performed from February to June 2001. This study took place in Agboville in Southern Côte d'Ivoire on 363 children, under the age of 15, regularly enrolled in school and selected by two-step clustered sampling. After the survey was completed, their stools were examined using 3 methods: direct exam, Kato's technique, and Graham's anal scotch-test. Infected students received an appropriate anti-helminthic treatment. After performing a test two weeks later, a new sample of 348 parasite-free children was made up and re-examined after three months, through the aforementioned techniques. In this sample, we assumed that students who were infested in the initial exam were "exposed", while those who were not infested in the first place were deemed to be "not exposed". The results showed that 135 students out of the 360 admitted for the first exam were infested; or a 37.5% of intestinal helminthiasis prevalence (IC95%=30.5-45). The prevalent parasite species were Necator americanus (15%), Trichuris trichiura (13.6%), Schistosoma mansoni (10%). Twenty-eight per cent of 135 infested students were infected by more than one parasite. After three months, the incidence rate of intestinal helminthiasis calculated out of the remaining 336 students was 7.7% (IC95%=4.4-13.1). The likelihood of re-infestation amounted to 3.4 (IC95%=1.5-7.3). The pattern of re-infestation rates according to socio-economic factors differed from that of infested prevalence. The prevalent parasites in re-infested patients were Trichuris trichiura (16.3%), Schistosoma mansoni (12.5%). All intestinal nematodes and Schistosoma mansoni were observed. The most frequent parasites species where those transmitted cutaneously. The high re-infestation rate suggests that intestinal helminthiasis in this region affects roughly the same children. These results show the necessity to continue our investigations in order to highlight essential hygienic factors in our long-term fight against intestinal helminthiasis.

Environmental influences on helminthiasis and nutritional status among Pacific schoolchildren

This paper describes a study undertaken to: (1) determine the prevalence of Ascaris lumbricoides, Trichuris trichiura and hookworm infections and nutritional status among Pacific Island school children; (2) identify factors influencing helminthiasis; (3) identify interventions to improve school health. A total of 3,683 children aged 5-12 years attending 27 primary schools in 13 Pacific Island countries were surveyed along with school environmental data. Stool samples were collected from 1996 children (54.2%) and analysed for ova and helminths. Total prevalence of helminthiasis was 32.8%. Anaemia prevalence was 12.4%. Children with helminthiasis and anaemia were found to be 8.7 times more likely to be stunted and 4.3 times more likely to be underweight than non-anaemic and non-infected children. Four significant environmental influences on helminthiasis were identified: (1) an inadequate water supply; (2); availability of a school canteen; (3) regular water/sanitation maintenance regimes; and (4) overcrowded classrooms. Helminthiasis was found to be strongly associated with anaemia, stunting and underweight and environmental influences identified. Although mass anti-helminthic drug administrations (MDA) have been taking place, reinfection is common as drug therapy alone is not enough. Programme effectiveness depends upon upgrading school environments to include an adequate water supply, controlled food preparation/provision, well-maintained water/sanitation facilities and class sizes of 30 students or less.

Community Perception and Readiness for Anti-Helminth Programmes in Rural Nepal

We report on the community perception of helminth infection and readiness to participate in and pay for a community-based anti-helminth programme in rural Nepal. For data collection, 28 focus group discussions (FGDs) were conducted in 28 communities. The FGD results revealed that community members were lacking in scientific knowledge about helminth infection. They also had an unusual perception about it - they believed that a ‘mul juka’ (vital worm) should reside in every person's stomach from birth, and must never be killed. Nonetheless, the results showed that the community members were willing to participate in and were ready to contribute their resources to the anti-helminth programmes as long as modern medicine would not kill the ‘mul juka’. Such community readiness provides us with hope for developing a sustainable anti-helminth programme at the community level through effective health education.

Current status of soil-transmitted helminths in Vietnam

This paper provides a review of surveys on soil-transmitted helminths that were done in Vietnam between 1990 and 2001. Prevalence estimates could be obtained for 29 of the 61 provinces. Extrapolating from this, it is estimated that 33.9 million people in Vietnam are infected with Ascaris (prevalence 44.4%), 17.6 million with Trichuris (prevalence 23.1%), and 21.8 million with hookworm (prevalence 28.6%). Prevalence of Ascaris and Trichuris showed a declining trend from the north to the south of the country. This is probably related to differences in climatic conditions. Hookworm prevalence is more evenly distributed throughout the country, but is concentrated in peri-urban and rural agricultural areas. Vegetable cultivation in which nightsoil is used as fertilizer is a risk factor for hookworm infection, especially among adult women. Helminth control programs should be targeted at school-age children in the northern provinces. Specific interventions are needed throughout the country for women of agricultural communities that are at risk for hookworm infection. There is clearly a need for more detailed analysis of risk factors to quantify the relative contribution of climatic, environmental, and human behavioral factors in the transmission of intestinal nematode infections in Vietnam.

Assessing eosinophil count as a marker of immune activation among human immunodeficiency virus-infected persons in sub-Saharan Africa

In 611 human immunodeficiency virus-infected persons who had not yet begun to receive antiretroviral therapy, we evaluated the linear association between absolute eosinophil count (as a surrogate for immune response to helminthic infection) and CD4+ T cell count, and between absolute eosinophil count and log virus load. Overall, no significant correlations were observed between eosinophil count and CD4+ T cell count, or between eosinophil count and log virus load.

Helminthic infections associated with the use of raw wastewater for agricultural purposes in Beni Mellal, Morocco

We aimed to determine the possible risks associated with raw wastewater use for agricultural purposes, particularly the transmission of helminthic infections among children. In a randomly-selected sample of 1343 children, 740 of them were from five regions using raw wastewater for agriculture, while 603 were from four control regions that do not use such water. The prevalence of helminthic infection was found to be significantly higher among children in regions using wastewater, compared to control regions. Behavioural characteristics and public water supply were found to be associated with higher infection rates. Adequate treatment of wastewater as well as public health education are highly recommended.

Epidemiological study of intestinal helminthiasis in a Marrakech raw sewage spreading zone

It has been suspected for some time that raw sewage is a potential source of protozoan and helminthic infections (10). Shuval et al. (16, 17) and W.H.O. (21) have shown that irrigating crops with untreated wastewater causes significant intestinal infections in both consumers and farm workers. This study compared the stools of "sewage farming" children exposed to raw sewage (El Azzouzia area) and those of a control group. Stool specimens from 253 exposed children and 275 controls were analyzed. 73% of the exposed were infected with one or more helminths verses 30% of the control group. The main parasites were Ascaris and Trichuris. The El Azzouzia children were more heavily infected and their polyparasitism index (PPI: 13%) was considerably higher than that of the controls (PPI: 2%). Thus "sewage farming" children are exposed to detectable risk from the parasitic nematodes in raw sewage.

Soil contamination with geohelminth ova in a tea plantation

OBJECTIVE

To determine the degree of soil pollution in an area of high prevalence and the risk of exposure to geohelminth infection.

DESIGN

A cross-sectional study.

SETTING

A division of a large tea plantation in Kandy.

SUBJECTS

All persons resident in one division of the tea plantation, above the age of 1 year.

MEASUREMENTS

Prevalence of geohelminth infection measured by microscopic examination of faeces of the study group. Soil samples from 38 specific locations, obtained on 3 different occasions, about 6 months apart, analysed for helminth ova. The average temperature, rainfall and the number of rainy days during the sampling period.

RESULTS

Of the 99 subjects of the study group, 77.7% were positive for at least one geohelminth infection. The prevalence rates for ascariasis, trichuriasis and hookworm infection were 54%, 28%, and 22% respectively. At the first sampling, 10.5% of the soil samples were positive for helminth ova with 7.8% and 2.6% samples showing Ascaris and Necator ova respectively. At the second sampling of the same locations nearly 40% of the samples were positive for helminth ova with 21.6%, 7.8% and 10.5% of the samples positive for Ascaris, Trichuris and Toxocara ova respectively. At the third sampling, 26.2% of the samples were positive with 21%, 2.6% and 2.6% of the samples positive for Ascaris, Trichuris and Toxocara ova respectively. Necator ova were found only once in 2.6% of the samples of the first sampling. The larger number of samples positive for helminth ova were in the second and the third samplings which coincided with high rainfall in the pre-sampling period.

CONCLUSIONS

The prevalence of geohelminthiases among the study group was high. Results of soil analysis confirmed continued contamination of soil in and around the home gardens and the work areas with human and dog faeces. With the knowledge of exact locations of soil pollution it was possible to advice the management on remedial measures.

Parasites of fish and risks to public health

A multitude of parasites have been reported in fish, but only a few species are capable of infecting humans. The most important of the helminths acquired by humans from fish are the anisakid nematodes (particularly Anisakis simplex and Pseudoterranova decipiens), cestodes of the genus Diphyllobothrium and digenetic trematodes of the families Heterophyidae, Opisthorchiidae and Nanophyetidae. Seafood-associated infections by acanthocephalans are rarely reported in humans. All of the helminths mentioned above are associated with social-cultural and behavioural factors, in particular the consumption of raw or undercooked seafood. Measures can be taken during harvesting, processing or post-processing (e.g., by the consumer) to mitigate the risks of infection. The seafood industry and government authorities can apply various programmes to reduce these risks, including good manufacturing practices (GMPs) and hazard analysis and critical control point (HACCP) systems. Such measures may include avoiding particular harvest areas, sizes of fish, or even particular species of fish. The method of capture, handling and storage of the catch can directly affect the quality of the seafood with regard to the presence and numbers of parasites. The extent of processing--including heading and gutting, candling and trimming--and the type of product derived (fresh, frozen, salted or pickled) can all contribute to the control of the risks posed by helminths. The most effective means of killing the parasites are either freezing or heat inactivation.

[Influence of socioeconomic conditions on the occurrence of intestinal helminthiases. Study of 1001 students in Abidjan (Ivory Coast)]

We report the results of epidemiological research carried out using a sample of 1,001 children between the ages of 4 and 15 in the city of Abidjan. The aim of the study was to explore the relationship between socioeconomic conditions and the occurrence of intestinal helminthiasis. The variables evaluated in this study were the monthly income of the parents, daily food budget per person, number of people sharing accommodation, availability of running water and electricity, availability of food near schools and regular anti-parasite treatment.

A comparative trial of a single-dose ivermectin versus three days of albendazole for treatment of Strongyloides stercoralis and other soil-transmitted helminth infections in children

A randomized trial carried out in rural Zanzibar comparing a single dose of 200 micrograms/kg of ivermectin and 400 mg/day for three days of albendazole for treatment of strongyloidiasis and other intestinal nematodes is described. In 301 children with Strongyloides stercoralis infection, treatment with ivermectin or albendazole resulted in cure rates of 83% and 45%, respectively. While both drugs were very effective against Ascaris lumbricoides, Trichuris trichiura was cured only in 11% (ivermectin) and 43% (albendazole) of the subjects, although the mean eggload was reduced by 59% and 92%, respectively. Ivermectin was ineffective against hookworms, while albendazole resulted in a cure rate of 98%. No severe side effects were recorded and mild side effects were of transient nature for both treatments. Therefore, ivermectin provides a safe and a highly effective single dose treatment for S. stercoralis and A. lumbricoides, while it is not an alternative for the treatment of T. trichiura and hookworm infections.

Granulomatous infections: etiology and classification

Granulomatous disorders are frequently due to a wide variety of infections. Over the past decade advances in molecular diagnostic techniques have allowed identification of organisms involved in granulomatous disorders that previously were of unknown etiology. On the basis of currently available information, granulomatous infections can now be classified in three categories. Group 1 infections are due to a well-recognized organism. Group 2 comprises infections due to organisms that have been recently identified in granulomas by molecular methods but are not readily isolated by conventional microbiological techniques. Group 3 consists of disorders for which the causal organisms have not yet been identified but are strongly suspected; further advances in diagnostic techniques will lead to reclassification of some of these disorders as group 2. This review describes the etiology, histopathologic features, and classification of granulomatous disorders, with an emphasis on those of groups 2 and 3.

Parasitic infections associated with malignancy and leprosy

Results of parasitic infections, as revealed by urine and stool examination was significant (P less than 0.05) in 43.3% of patients suffering from different malignant diseases and non significant (P greater than 0.05) in 29.3% of leprosy patients compared to 22% in control subjects. The most prevalent parasites were E. histolytica and G. lamblia. Cryptosporidium occysts were not detected. By stool examination and culture, S. stercoralis larvae were detected only in the malignancy group. The most common parasites occurring concomitantly were A. duodenale and S. stercoralis. By the IFAT, strongyloidiasis gave significantly higher positive results in the malignancy group than in the leprosy and control groups. IFAT for toxocariasis, showed highly significant positivity in the leprosy group and significantly positivity in the malignancy group. For toxoplasmosis, it showed highly significant positive results in both leprosy and malignancy groups. Eosinophilia was significantly more prominent among malignancy patients and insignificant among those with leprosy. Parasitic infection detected by urine and stool examination among patients with eosinophilia was found in 76% of the malignancy patients and in 66.7% of the leprosy patients.

The pattern of human intestinal helminth infections in farming communities in different parts of Ondo State, Nigeria

Faecal samples collected from people inhabiting project areas of Owena River Basin and Rural Development Authority at Okitipupa, Akure Ifon and Ajowa which are located in different geographical areas of Ondo State, Nigeria, were examined for helminth ova and larvae. The common worms were Ascaris lumbricoides, Trichuris trichiura and hookworms with average occurrences of 43.1% 23.4% and 17.0% respectively. Infections were highest in subjects in the age groups of 6-10 and 11-15 years and lowest in those over 25 years. The frequency of occurrence of Ascaris and Trichuris were high in all towns. Hookworms infection rates were 24.6%, 19.7%, 21.5% and 2.1% at Akure. Ifon, Ajowa and Okitipupa respectively. The low hookworm incidence at Okitipupa which is near the coast has been attributed to the heavy soils of clay and silt coupled with heavy rainfall.

Influence of pollution on parasites of aquatic animals

We have tried to draw attention to an increasing body of evidence (from several publications) that parasites of fish might be useful indicators of pollution. Several types of pollutants, including domestic sewage, pesticides, polychlorinated biphenyls, heavy metals, pulp and paper effluents, petroleum aromatic hydrocarbons, acid rain, and others, are known to affect aquatic animals. Many of the latter are parasitized and, under natural environmental conditions, most fish parasites are believed to cause little or no harm. However, chronic exposure to pollutants over a period of time causes biochemical, physiological and behavioural host changes that ultimately can influence the prevalence and intensity of parasitism. Some of these changes include host nutrition, growth and reproduction. Macroscopic lesions might not always be apparent, but subtle disorders in several specific tissues and organs might occur. Pollutants might promote increased parasitism in aquatic animals, especially fish, by impairing the host's immune response or favouring the survival and reproduction of the intermediate hosts. Alternatively, decreased parasitism might ensue through toxicity of the pollutant to free-living stages and intermediate hosts or by alteration of the host's physiology. Experimental studies indicate that the numbers of ectoparasites such as trichodinid ciliates and monogeneans increase significantly on the gills following exposure to a pollutant, and this is supported by field data on other ciliates and monogeneans where evidence of pollution has been clearly demonstrated. There is also evidence that endoparasitic protozoons, such as myxozoons, microsporans and haematozoons, all of which are capable of proliferating in their hosts, increase substantially in prevalence and intensity when interacting with pollutants. The period of patency might also be prolonged in haematozoan infections. Most reports of pollution effects on endoparasites suggest increased parasitism in fish hosts. This also applies to fish living in areas which receive thermal effluents. Parasites might in turn enhance their hosts' susceptibility to pollutants, and information in support of this view is accumulating. Finally, immunosuppression represents one of the underlying mechanisms influencing increased parasitism. Thus, while published information suggests more than a casual connection between fish parasites and pollution, further research is needed to establish the cause-and-effect relationship and at the same time take cognizance of histopathological effects of the toxic agents and their concentrations in water. Areas for future research are recommended.

[Sanitary-helminthological status of urban environment in the foci of animal helminthiasis]

As result of sanitary-helminthological studies it has been found out, that under the conditions of urban agglomeration a great number of dogs, their uncontrolled maintenance and access to various objects induce intensive environmental pollution with zoohelminthologic causative agents and provides a high risk of infection of the population with causative agents of such diseases as toxocariasis++ and echinococcosis. Adherence to sanitary-veterinary rules of dogs maintenance prevents to a significant degree dispersion of the invasion matter in the environment.

Infectious and toxic syndromes from fish and shellfish consumption. A review

Primary care physicians care for large numbers of patients presenting with "food poisoning" or gastroenteritis. When a patient who presents with acute gastrointestinal illness, especially in conjunction with neurologic or cutaneous symptoms, is evaluated, the history should focus on past seafood consumption (particularly raw or undercooked seafood). The infectious syndromes are generally self-limited and respond to supportive care; exceptions are those caused by Vibrio cholerae and Vibrio vulnificus, which may be fatal in severe cases. The toxic syndromes are uncommon and fall into two categories: the histaminelike syndrome of scombroid poisoning and the neurotoxic syndromes, including ciguatera, paralytic shellfish poisoning, and puffer fish poisoning. Recognition of these clinical entities may lead to more appropriate management and preventive measures.

[Parasitic intestinal infestations and infections]

An overview is given dealing with global significance, clinical course and chemotherapie of some important helminthic and protozoal infections of human intestine.

Worms, wells and water in western Madagascar

This study of schistosomiasis and intestinal parasites was carried out on 496 children in the Firaisana (District) of Ankilivalo in Western Madagascar. The prevalence of these parasites was determined and data collected on nutrition, agriculture and the use of water in order to gain an understanding of the transmission and effects of these parasites. Recommendations for their control are suggested. In two schools within the area of a major irrigation scheme the prevalence of urinary schistosomiasis was 69%, and 50% suffer from at least one intestinal worm. In a school outside the main irrigation area, the prevalence of schistosomiasis was much lower (7%). Ultimately the control of schistosomiasis will depend on improvements to the irrigation and drainage infrastructure, and in standards of sanitation. However, chemotherapy is the only method of bringing the disease under control in the short term.

Parasites of moose (Alces alces) from an agricultural area of eastern Ontario

Viscera of 16 moose and hide samples of 24 moose (Alces alces) shot in eastern Ontario in 1985 were examined for parasites. Two species of trematodes, one species of cestode, five species of nematodes and one species of tick were recovered. One nematode species, Trichuris discolor, is reported for the first time from moose. Our results suggest that the parasite fauna of the moose may have been influenced by the absence or scarcity of other species of wild cervids or carnivores and by the presence of domestic livestock.

The behaviour of Homo sapiens, the forgotten factor in the transmission of tropical disease

The behaviour of the pathogens responsible for tropical disease and the behaviour of the hosts other than man are both studied in great detail, but the behaviour of man, the third component in these cycles of transmission, is for the most part totally and inexplicably disregarded. Even when the pathogens are actively brought to us through the agency of an arthropod host, we too often ease the passage of the vectors either by unthinkingly providing facilities for their breeding or by neglecting the simple steps that can be taken to prevent their feeding on us. The problem resolves itself into two parts, (i) the collection and collation of relevant data on human behaviour, and (ii) the taking of steps to change this behaviour. Part two has recently been greatly facilitated by the development of radio transmission via artificial satellite. While WHO is now making a start on both these aspects it is doing so at a relatively low level. Instead, the two phases of this new approach should be given top priority even if it means large scale reorganization of relevant university departments and even of WHO itself. We have, after all, had almost 100 years to try out the old methods and, as far as the Third World is concerned, they have for the most part failed.

Indirect effects of soil and water on animal health

Some variations in animal health among geographic areas are associated with variations in soils, water supplies or soil parent materials. Geochemical bases for health problems arising from essential nutrient element deficiencies or from toxic levels or imbalances of several elements are widely recognized. Less attention has been directed to the possibilities of geochemical influences upon regional differences in health resulting from pathogens, parasites, mycotoxins and poisonous plants. This review is an effort to collect and interpret such evidence as has been published on the subject since Louis Pasteur's original observation associating soil character and probability of anthrax.