Excreta disposal facilities and intestinal parasitism in urban Africa: preliminary studies in Botswana, Ghana and Zambia

Parasitic contamination of some fresh and collected vegetables from Mosul City markets

The current study specifies the rate of spreading the parasites in fresh vegetables sold in shops located on the left and right sides of the city of Mosul. 600 samples were collected, 300 for each side left and right, with 15 samples of each Lettuce, Celery, Pepper, Tomatoes, Onions and Carrots. Results showed significant differences in the rates of contaminating variables with intestinal parasites at probability level (p<0.05) on both sides, where it was noticed that the percentage of contamination on the right side (39%) was higher than the one on the left side(26%). The results also showed that fresh vegetables are contaminated with three types of intestinal parasites: Entamoeba histolytica, Giardia Lamblia, Entamoeba coli, and four types of intestinal worms as follows: Ascaris lumbricoides, Trichuris trichura, Hymenolypis nana, Enterobius Vermiculoris. The highest contamination percentage with intestinal protozoa was found with Entamoeba histolytica parasite (67%) on the left side. On the right side, the percentage of contamination was Entamoeba histolytica (50%) in each of the tomato plants and coriander., and the highest percentage of contamination with intestinal worms was by Ascaris lumbricoides worm on the left side (40%) and in the right side (29%). Also shown from the results, the percentage of single contamination in the fresh vegetables was higher than the double and triple contamination. The single contamination was found with a percentage of (82-95%) on both sides, respectively and also noticed in the current study, the leafy vegetables (lettuce and celery) and Tomato, which are the most vegetables contaminated with parasites in both sides in comparison with the rest types of vegetables. Keywords Contamination; intestinal parasites, vegetables; left and right sides

Characteristics of microbial aerosol particles dispersed downwind from rural sanitation facilities: Size distribution, source tracking and exposure risk

Bioaerosols containing pathogens released from waste and wastewater treatment facilities pose potential health risks to workers on-site and residents downwind. In this study, sampling sites were set up at rural garbage stations (GS-1 and GS-2) and sewage treatment station (STS) to investigate the emission and diffusion characteristics of bioaerosols. High-throughput sequencing was utilized to assay the intestinal bacteria population, while the health risks associated with bioaerosols exposure were estimated based on average daily dose rates (DD). Traceability analysis was used to determine the percentages of intestinal bacteria from GS-1, GS-2 and STS. The recorded emission levels of bioaerosols in the air surrounding GS-1, GS-2, and STS were 5053, 6299, and 4795 CFU/m³, containing 1599, 2244, and 2233 CFU/m³ of intestinal bacteria, respectively. Most of the bioaerosols were coarse particles with size larger than 4.7 μm. Methylobacterium, Rhizobium, Pseudomonas, Enterobacteriaceae, and Brucella presented in the air were originally in rural waste and wastewater. STS and GS-2 were potential sources of intestinal bacteria. With increasing distance from the sources, the concentration of bioaerosols decreased gradually. On-site workers and residents were predominantly affected by bioaerosols through inhalation. The exposure risks via inhalation and skin contact for children were much higher than that for adults. The purpose of this study was to provide preliminary data for bioaerosols control and their risks reduction released from rural sanitation facilities.

Household socio-economic position and individual infectious disease risk in rural Kenya

The importance of household socio-economic position (SEP) in shaping individual infectious disease risk is increasingly recognised, particularly in low income settings. However, few studies have measured the extent to which this association is consistent for the range of pathogens that are typically endemic among the rural poor in the tropics. This cross-sectional study assessed the relationship between SEP and human infection within a single community in western Kenya using a set of pathogens with diverse transmission routes. The relationships between household SEP and individual infection with Plasmodium falciparum, hookworm (Ancylostoma duodenale and/or Necator americanus), Entamoeba histolytica/dispar, Mycobacterium tuberculosis, and HIV, and co-infections between hookworm, P. falciparum and E. histolytica/dispar, were assessed using multivariable logistic and multinomial regression. Individuals in households with the lowest SEP were at greatest risk of infection with P. falciparum, hookworm and E. histolytica/dispar, as well as co-infection with each pathogen. Infection with M. tuberculosis, by contrast, was most likely in individuals living in households with the highest SEP. There was no evidence of a relationship between individual HIV infection and household SEP. We demonstrate the existence of a household socio-economic gradient within a rural farming community in Kenya which impacts upon individual infectious disease risk. Structural adjustments that seek to reduce poverty, and therefore the socio-economic inequalities that exist in this community, would be expected to substantially reduce overall infectious disease burden. However, policy makers and researchers should be aware that heterogeneous relationships can exist between household SEP and infection risk for different pathogens in low income settings.

The time-temperature relationship for the inactivation of Ascaris eggs

A time-temperature plot presenting the inactivation of Ascaris eggs is expanded with additional literature data. The information is of value to designers and operators of sanitation equipment who have Ascaris inactivation as an objective.

Intestinal helminth infections among children of district Shopian of Kashmir Valley, India

Intestinal helminth infections are amongst the most common infections worldwide. Studies in other districts of Kashmir Valley revealed a high prevalence of intestinal helminth infections among the children. The objectives of the current study were to determine the prevalence of intestinal helminth infections among children of Shopian district and to identify associated socio-demographic and environmental actors, behavioral habits and also related complaints. Stool samples were collected from 352 children and a questionnaire was filled for each case. The samples were processed using both simple smear and zinc sulphate concentration methods, and then microscopically examined for intestinal helminths. Of the 352 children surveyed, 75.28 % had 1, or more, helminth parasites. Prevalence of Ascaris lumbricoides was highest (71.8 %), followed by Trichuris trichiura (26.4 %), Enterobius vermicularis (13.9 %) and Taenia saginata (5.3 %). Conditions most frequently associated with infection included the age group, water source, boiled or unboiled water, defecation site, personal hygiene, and the extent of maternal education. The study shows a relatively high prevalence of intestinal helminths and suggests an imperative for the implementation of control measures.

Socio–economic and behavioural factors affecting the prevalence ofAscarisinfection in a low-country tea plantation in Sri Lanka

The identification of the factors that affect the prevalences of geohelminthiases should help to maximize the effectiveness of programmes for the control of these diseases. In the present study, the relationships between the prevalence and intensity of human infection with Ascaris and the availability of sanitary facilities, socio-economic status and personal health habits have been explored in Sri Lanka. The 176 subjects, who lived on a low-country tea plantation, were aged 2-50 years (median = 13 years) and were investigated between the July and December of 2000. When the prevalence and intensity of Ascaris infection were determined, using Kato-Katz smears, 50.0% of the subjects were found to be secreting the eggs of the parasite. Almost all (96.6%) of the subjects lived in terraces of one-room houses built by the plantation owners, and only 30.7% had access to a latrine. Most (90.3%) obtained their drinking water from common taps, and 48.8% boiled their drinking water. The subjects who only drank water that had been boiled and those who washed their hands before meals were relatively unlikely to be infected (P < 0.05 for each). In congested living conditions with poor sanitary facilities, the level of faecal contamination of the environment is invariably high. Even under these conditions, however, good hygiene and the boiling of all drinking water can reduce the risks of Ascaris infection. In the study setting and in similar environments, regular anthelmintic therapy, improvements in housing conditions and sanitary facilities, and health education, to promote risk-reducing patterns of behaviour, would all be beneficial.

Association between HLA-DQ genotypes and haplotypes vs Helicobacter pylori infection in an Indonesian population

BACKGROUND

Helicobacter pylori is an important gastrointestinal pathogen related to the development of not only atrophic gastritis and peptic ulcer, but also gastric cancer. Human leukocyte antigens (HLA) may play particular roles in host immune responses to bacterial antigens. This study aimed to investigate the association between HLA-DQA1 and DQB1 genotypes and haplotypes vs H. pylori infection in an Indonesian population.

METHODS

We selected 294 healthy participants in Mataram, Lombok Island, Indonesia. H. pylori infection was determined by urea breath test (UBT). We analyzed HLA-DQA1 and DQB1 genotypes by PCR-RFLP and constructed haplotypes of HLA-DQA1 and DQB1 genes. Multiple comparisons were conducted according to the Bonferroni method.

RESULTS

The H. pylori infection rate was 11.2% in this Indonesian population. The DQB1*0401 genotype was noted to be associated with a high risk of H. pylori infection, compared with the DQB1*0301 genotype. None of the HLA-DQA1 or DQB1 haplotypes were related to the risk of H. pylori infection.

CONCLUSIONS

The study suggests that HLADQB1 genes play important roles in H. pylori infection, but there was no statistically significant association between HLA-DQA1 or DQB1 haplotypes and H.pylori infection in our Lombok Indonesian population.

Effects of sewerage on diarrhoea and enteric infections: a systematic review and meta-analysis

BACKGROUND

Sanitation is inadequate in most cities in developing countries, with major effects on infectious disease burden: in this situation, is piped sewerage an appropriate solution, or should efforts focus on systems based on onsite solutions, such as latrines? We reviewed the effects of the presence of sewerage systems on diarrhoeal disease and related outcomes. We included only observational studies because so far there have been no randomised controlled trials.

METHODS

We identified relevant studies by use of a comprehensive strategy including searches of Medline and other databases from 1966 to February, 2010. In studies that compared sewerage with one other sanitation category, we used relative risk (RR) estimates for sewerage versus the other category. When a single study made two or more comparisons, we calculated a weighted average RR value, and used this value in our meta-analysis. We used the most adjusted RR estimate provided by the authors; if no adjusted estimate was available, we used the crude estimate. To obtain pooled-effect estimates, meta-analyses were done by use of an inverse variance method-ie, the study-specific adjusted log ORs for case-control and cross-sectional studies, and log RRs for cohort studies, were weighted by the inverse of their variance to compute a pooled RR with 95% CI.

FINDINGS

25 studies investigated the association between sewerage and diarrhoea or related outcomes, including presence of intestinal nematodes. Pooled estimates show that sewerage systems typically reduce diarrhoea incidence by about 30% (RR 0.70, 95% CI 0.61-0.79), or perhaps as much as 60% when starting sanitation conditions are very poor. Studies with objective outcome measures showed even stronger pooled effect than studies that assessed diarrhoea incidence with interviews, while sensitivity analysis indicated that the effect remains even if we assume strong residual confounding.

INTERPRETATION

Sewerage interventions seem to reduce the incidence of diarrhoea and related outcomes. However, we urge cautious interpretation of these findings, because, in many contexts, sewerage might be less cost effective and sustainable than onsite alternatives.

FUNDING

None.

Geohelminth infection and re-infection after chemotherapy among slum-dwelling children in Durban, South Africa

The prevalences and intensities of Ascaris lumbricoides, Trichuris trichiura and hookworm (probably Necator americanus) infection were measured in the young children (aged 2-10 years) living in 10 urban slums in Durban, South Africa. Re-infection was assessed at 4-6 and 12 months post-treatment. The baseline prevalences of A. lumbricoides and T. trichiura were 81.7%-96.3% and 54.5%-86.2%, respectively, and the corresponding geometric mean intensities were 960 and 91 eggs/g faeces. Most (85%) of the children found infected with A. lumbricoides and 23% of those found infected with T. trichiura had moderate-heavy infections. A few of the children investigated had intensities of Ascaris and Trichuris infection that were considerably higher than those previously recorded in South Africa. The baseline prevalences of hookworm infection (0%-20% in individual slums, with a mean of 4.7%) and intensities of such infection (geometric mean=17 eggs/g) were relatively low. Albendazole proved very effective against A. lumbricoides and hookworm but less so against T. trichiura. Re-infection by A. lumbricoides and T. trichiura reached pre-treatment prevalences by 4-6 months post-treatment in some of the slums and by 12 months in all the other slums. By 12 months post-treatment, the intensities of A. lumbricoides infection had reached their pre-treatment levels while those of T. trichiura infection were higher than at baseline. Approximately 50% of children had moderate-heavy T. trichiura infections at 12 months post-treatment compared with approximately 23% at baseline. Hookworm infections did not re-appear after treatment. The results show clearly that urban slums should be included in any future helminth-control programmes in South Africa.

Socio-environmental factors and ascariasis infection among school-aged children in Ilobu, Osun State, Nigeria

The risk factors predisposing children to ascariasis transmission in a rural community of Osun State, Nigeria were investigated from November 2005 to April 2006. Children below 16 years of age were examined at the household level after information on biodata, access to water supply and sanitation, socio-economic status of their parents and degree of cohabitation with their parents was collected using a questionnaire. Of 440 children examined, overall prevalence was 60% and median intensity was 1548 eggs per gram (epg) (min. 48 epg; max. 55464 epg). Infection patterns were gender comparable and age dependent, with peak prevalence (67.8%) occurring in children aged 5-9 years and peak median intensity (4368 epg) in children aged >or=15 years. Logistic regression analysis revealed that prevalence was influenced by patterns of water supply and sanitation, parents' educational background, number of biological parents living with a child and number of playmates a child has. These findings suggest that socio-environmental risk factors which play a role in disease transmission need to be taken into account when formulating sustainable control strategies for ascariasis and other intestinal parasites in Nigeria and elsewhere.

Aquaculture practices and potential human health risks: current knowledge and future priorities

Annual global aquaculture production has more than tripled within the past 15 years, and by 2015, aquaculture is predicted to account for 39% of total global seafood production by weight. Given that lack of adequate nutrition is a leading contributor to the global burden of disease, increased food production through aquaculture is a seemingly welcome sign. However, as production surges, aquaculture facilities increasingly rely on the heavy input of formulated feeds, antibiotics, antifungals, and agrochemicals. This review summarizes our current knowledge concerning major chemical, biological and emerging agents that are employed in modern aquaculture facilities and their potential impacts on public health. Findings from this review indicate that current aquaculture practices can lead to elevated levels of antibiotic residues, antibiotic-resistant bacteria, persistent organic pollutants, metals, parasites, and viruses in aquacultured finfish and shellfish. Specific populations at risk of exposure to these contaminants include individuals working in aquaculture facilities, populations living around these facilities, and consumers of aquacultured food products. Additional research is necessary not only to fully understand the human health risks associated with aquacultured fish versus wild-caught fish but also to develop appropriate interventions that could reduce or prevent these risks. In order to adequately understand, address and prevent these impacts at local, national and global scales, researchers, policy makers, governments, and aquaculture industries must collaborate and cooperate in exchanging critical information and developing targeted policies that are practical, effective and enforceable.

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.

The prevalence, intensities and risk factors associated with geohelminth infection in tea-growing communities of Assam, India

OBJECTIVE

To determine the prevalence, intensity and associated risk factors for infection with Ascaris, hookworms and Trichuris in three tea-growing communities in Assam, India.

METHODS

Single faecal samples were collected from 328 individuals and subjected to centrifugal flotation and the Kato Katz quantitation technique and prevalence and intensities of infection with each parasite calculated. Associations between parasite prevalence, intensity and host and environmental factors were then made using both univariate and multivariate analysis.

RESULTS

The overall prevalence of Ascaris was 38% [95% confidence interval (CI): 33, 43], and the individual prevalence of hookworm and Trichuris was 43% (95% CI: 38, 49). The strongest predictors for the intensity of one or more geohelminths using multiple regression (P < or = 0.10) were socioeconomic status, age, household crowding, level of education, religion, use of footwear when outdoors, defecation practices, pig ownership and water source.

CONCLUSION

A universal blanket treatment with broad-spectrum anthelmintics together with promotion of scholastic and health education and improvements in sanitation is recommended for helminth control in the communities under study.

The role of health education and sanitation in the control of helminth infections

Health education and sanitation are two important components of primary health care system introduced by the World Health Organization (WHO) as a basis for the prevention and control of communicable diseases. However, the roles of health education and sanitation in disease control have been controversial, especially in the wake of recent advances in safe and effective oral drugs. This article has reviewed the various health education and sanitation interventions around the world to determine what roles they have played in the past relative to other intervention strategies and the role they have to play in future control efforts. It appears clear-cut from the review, that while chemotherapy has been and will remain the best option for morbidity control, sanitation has an important role to play not only to sustain the benefits of chemotherapy but also to protect the uninfected. Health education that is effective, simple and low-cost remains the only tool for creating the enabling environment for both chemotherapy and sanitation to thrive.

Ascaris lumbricoides among children in rural communities in the Northern Area, Pakistan: prevalence, intensity, and associated socio-cultural and behavioral risk factors

The prevalence and intensity of Ascaris lumbricoides in 492 children from five rural villages in the Northern Area of Pakistan was examined. The overall prevalence of A. lumbricoides was 91% (95%CI 88.6-93.6) with geometric mean (GM) egg count intensities of 3985 eggs per g (epg). The most intense A. lumbricoides infections were found in children aged 5-8 years. We also investigated selected socio-cultural and behavioral variables for A. lumbricoides infections that might be relevant for the design of appropriate prevention and control programs. Univariate analysis associated A. lumbricoides intensity with age (P=0.004), location of household (P<0.01), defecation practices (P=0.02), soil eating habit (P<0.01), hand washing after defecation (P<0.01), and living with children under 5 years old (P=0.02). Multivariate analysis identified the children's age 5-8 (P<0.01), location of household in Surngo, Askole, and Stakchun where the pilot health care model activities were not done (P<0.01), and living with children under 5 years old (P=0.03) as variables statistically associated with the intensity of A. lumbricoides. The results indicated that there were certain clear risk factors in A. lumbricoides transmission, and that its intensity was influenced by age-related behavioral and environmental factors that contribute to exposure.

Ascaris lumbricoides infection and environmental risk factors in an urban African setting

Identification of appropriate strategies for controlling gastro-intestinal nematodes in communities depends, in part, on an understanding of the conditions that increase risk of exposure to infective stages. The present study was conducted in Lubumbashi, Zaire. The objectives were to identify features of the environment and living conditions that were significant predictors of Ascaris lumbricoides infection, and to determine whether the same predictors were important in populations living in subdivisions of lower (LSES) and higher (HSES) socio-economic status. Forty-two households from each of three subdivisions (two LSES and one HSES) were selected at random. Mothers were interviewed, observations on the environment around the home were recorded, and single stool samples, collected from all children and mothers, were examined for nematode eggs. Maternal education was a significant predictor of A. lumbricoides intensity in both LSES and HSES subdivisions. Factors related to poor sanitation (open defecation and high number of people using the same toilet) were important in the LSES subdivisions but not in the HSES subdivision. In contrast, the ratio of relatives to direct family members per household was a significant predictor of high intensity of infection in the HSES subdivision, but not in the LSES subdivisions, indicating that relatives and live-in visitors contribute to Ascaris transmission in the HSES population.

Child morbidity patterns in Ethiopia

This study is based on the 1983 Rural Health Survey of Ethiopia. Patterns and levels of child morbidity by age, sex, geographic region, and sanitary facilities are examined. Morbidity levels peak in the second year of life. Diarrhoeal diseases are of major importance, especially among infants and toddlers. Parasitic diseases, and respiratory diseases other than pneumonia, become increasingly important with age. There are no significant sex differentials in morbidity except for higher rates of diarrhoeal diseases among female children. Geographic differentials are quite marked with particularly high morbidity levels from all disease types in the western mountainous regions of Ethiopia. Access to high quality drinking water, a latrine, and garbage disposal, are strongly related to reduced overall morbidity levels, though not necessarily to reduced diarrhoeal disease levels.

Population ecology of intestinal helminth infections in human communities

The distribution of worm burdens in human populations is a major determinant of both the dynamics of transmission and the level of community morbidity. The distribution exhibits convexity with host age, which appears to correlate with exposure in the young age-classes but not in adults, and may be evidence for the development of an acquired immune response. The distribution between individuals is typically overdispersed. Individuals are predisposed to high (or low) intensity of infection and to a correspondingly high (or low) rate of acquisition of infection. A major epidemiological question is whether this reflects individual differences in environmental exposure or susceptibility. Environmental studies that have observed clustering of intense infection in particular households are supportive of either mechanism. Individual host behaviours that predispose to infection have an overdispersed distribution and may alone, or as compounding factors, generate the observed distribution of infection intensity. Factors such as host nutrition and physiology may modify host immune-responsiveness and hence susceptibility. Preliminary evidence suggests correlates between infection intensity and HLA class II antigens, and tentatively implies a genetic factor in susceptibility. These findings suggest that further understanding of the relative importance of environmental factors and resistance to the acquisition of intense infection is dependent upon a multidisciplinary approach to epidemiological field study.

The clinical significance of gastrointestinal helminths--a review

Gastrointestinal helminths (nematodes, trematodes and cestodes) constitute some of the most common and important infective agents of mankind and are responsible for much morbidity and some mortality. Whereas many symptoms and signs are confined to the intestine and less often the associated digestive organs, systemic manifestations are also numerous; this applies especially to indigenous populations of developing 'Third World' countries. Using a clinical classification these organisms can be broadly separated into those involving the small-intestine and those which have a colo-rectal distribution; of the former, a minority has been causally related to intestinal malabsorption. Clearly, however, not all gastrointestinal helminths are associated with disease and it is important to be able to separate these two groups; when present at high concentration and especially in infants and children some of the least pathogenic are not, however, entirely asymptomatic. Maintenance of a high 'index of suspicion' is necessary and this applied especially to 'western' populations in whom rapid and extensive travel to areas of the world with substandard sanitation and contaminated food and water supplies is now common; first evidence of infection in them may result from serious clinical complications. Recent advances have focussed on treatment, and especially the introduction of the benzimidazole compounds (especially albendazole) for nematode, and praziquantel for cestode, infections. Treatment of strongyloidiasis remains, however, unsatisfactory. Mass elimination of gastrointestinal helminths in developing 'Third World' countries remains a major challenge.

Piped water supply and intestinal parasitism in Zimbabwean schoolchildren

The prevalence of intestinal parasitism in primary schoolchildren in three areas, communal (peasant farm) lands, commercial farms and urban townships, was assessed by examination of concentrated and stained stool specimens to determine the effect of water supply on intestinal parasitism. Piped water in communal lands was associated with decreased frequency of schistosomiasis and hymenolepiasis, but not with decreased frequency of protozoa. Schistosomiasis was very common in commercial farm labour communities, particularly on farms adjoining the local river, despite the availability of stored borehole water supplied through communal taps. The prevalence of intestinal parasitism in children from urban areas with municipal water supplied to taps in each household was similar to that of children in communal areas who obtained water from surface streams. The frequency of Giardia lamblia infection was higher in urban than in rural schoolchildren, and within communal areas was higher in children with access to protected borehole water. The provision of piped water was, therefore, not found to be associated with reduced prevalence of intestinal parasitism, though additional factors such as frequency of contact with infected water, the provision of ancillary improvements and the actual usage of available water supplies would need to be more closely assessed.

Social and environmental factors associated with diarrhoea and growth in young children: child health in urban Africa

This study investigates the relationship between social and environmental variables and diarrhoea and growth in children aged between 6 and 36 months in an urban area of The Gambia, West Africa. The social and environmental conditions of 493 children were observed and recorded over a period of 12 months. Two hundred and seventy-seven children were under weekly diarrhoea surveillance for a 15 week period during the wet season and 322 children had anthropometric measurements taken in May and September. Computer analysis was used to determine association between single and multiple environmental and social factors and diarrhoea prevalence and growth. The results of the diarrhoea surveillance showed that there was considerable variation between individual children. Thirty children had no diarrhoea during the period of surveillance and 30 had diarrhoea for over 24% of the time, with 2 children having diarrhoea for more than 50 days out of a total of 105. None of the social and environmental variables recorded showed a significant relationship with diarrhoea prevalence. The anthropometric measurements showed that at the end of the wet season, in September, 23% of children in this age group were less than 90% of the National Centre for Health Statistics standards of height for age and several of the variables recorded showed a statistically significant association with this measurement.