Prevalence Of Heavy Infection Research Articles

Update on the Status of urogenital schistosomiasis in Some Communities of Ebonyi State, Nigeria

Background: Schistosomiasis is one of the most common parasitic infections in the world, particularly in sub-Saharan Africa, ranking second only to malaria in terms of its socio-economic and public health importance in tropical and subtropical areas. There is an urgent need for updated information on the intensity of the disease at the community level to ensure effective disease monitoring. Materials and methods: The study was carried out in sixteen communities in the four local government areas of Ebonyi State. A total of 1,800 urine samples were collected from people of all ages randomly selected for this study. Urine samples were examined for Schistosoma haematobium egg using the standard parasitological method of diagnosis. Haematuria was evaluated using reagent test strips. Results: In this study, 342 (19.0%) persons were infected with S. haematobium. The infection was recorded in all the Communities in the study area, with Enyibichiri having the highest prevalence, n=39 (32.2%), followed by Umuoghara, n = 26 (25.5), while Oshugbu Community had the least prevalence, 5 (6.6%). More males, 225 (20.3%) than females, 117 (16.9%) were significantly infected. Infection prevalence was higher significantly (27.3%) among the age group 11-20 years. Those with light infection intensity 207 (60.5%) were excreting below 50 eggs/10ml urine, 110 (32.2%) had moderate infection intensity excreting between 50-100 eggs/10ml urine while 25 (7.3%) had heavy infection intensity excreting above 100egg/10ml urine. Peak intensity 14 (10.2%) was recorded among 11-20 egg groups. Prevalence of light and moderate intensities varied significantly (P<0 .05) when compared with the prevalence of heavy infection in different age groups, which was not significantly different (P> 0.05). The prevalence of haematuria was 188 (55.0%). The highest prevalence of haematuria (86; 62.3%) was recorded in the age group 11-20 years, while the least was recorded in age 31-40. Conclusion: Based on the findings of this study, the prevalence of urinary schistosomiasis infection in the Central Ebonyi State falls within the WHO classification of endemicity. Urgent need for decisive interventions through mass chemotherapy, focal application of molluscicides in the water bodies during the dry season and sanitation facilities are recommended. Health education is highly advocated

Contributions of the Schistosomiasis Consortium for Operational Research and Evaluation (SCORE) to Schistosomiasis Control and Elimination: Key Findings and Messages for Future Goals, Thresholds, and Operational Research.

.Herein, we summarize what we consider are major contributions resulting from the Schistosomiasis Consortium for Operational Research and Evaluation (SCORE) program, including its key findings and key messages from those findings. Briefly, SCORE’s key findings are as follows: i) biennial mass drug administration (MDA) with praziquantel can control schistosomiasis to moderate levels of prevalence; ii) MDA alone will not achieve elimination; iii) to attain and sustain control throughout endemic areas, persistent hotspots need to be identified following a minimal number of years of annual MDA and controlled through adaptive strategies; iv) annual MDA is more effective than biennial MDA in high-prevalence areas; v) the current World Health Organization thresholds for decision-making based on the prevalence of heavy infections should be redefined; and vi) point-of-care circulating cathodic antigen urine assays are useful for Schistosoma mansoni mapping in low-to-moderate prevalence areas. The data and specimens collected and curated through SCORE efforts will continue to be critical resource for future research. Besides providing useful information for program managers and revision of guidelines for schistosomiasis control and elimination, SCORE research and outcomes have identified additional questions that need to be answered as the schistosomiasis community continues to implement effective, evidence-based programs. An overarching contribution of SCORE has been increased cohesiveness within the schistosomiasis field-oriented community, thereby fostering new and productive collaborations. Based on SCORE’s findings and experiences, we propose new approaches, thresholds, targets, and goals for control and elimination of schistosomiasis, and recommend research and evaluation activities to achieve these targets and goals.

Modeling Approaches to Predicting Persistent Hotspots in SCORE Studies for Gaining Control of Schistosomiasis Mansoni in Kenya and Tanzania.

BackgroundSome villages, labeled “persistent hotspots (PHS),” fail to respond adequately in regard to prevalence and intensity of infection to mass drug administration (MDA) for schistosomiasis. Early identification of PHS, for example, before initiating or after 1 or 2 years of MDA could help guide programmatic decision making.MethodsIn a study with multiple rounds of MDA, data collected before the third MDA were used to predict PHS. We assessed 6 predictive approaches using data from before MDA and after 2 rounds of annual MDA from Kenya and Tanzania.ResultsGeneralized linear models with variable selection possessed relatively stable performance compared with tree-based methods. Models applied to Kenya data alone or combined data from Kenya and Tanzania could reach over 80% predictive accuracy, whereas predicting PHS for Tanzania was challenging. Models developed from one country and validated in another failed to achieve satisfactory performance. Several Year-3 variables were identified as key predictors.ConclusionsStatistical models applied to Year-3 data could help predict PHS and guide program decisions, with infection intensity, prevalence of heavy infections (≥400 eggs/gram of feces), and total prevalence being particularly important factors. Additional studies including more variables and locations could help in developing generalizable models.

Improving public health control of schistosomiasis with a modified WHO strategy: a model-based comparison study

SummaryBackgroundSchistosomiasis is endemic in many low-income and middle-income countries. To reduce infection-associated morbidity, WHO has published guidelines for control of schistosomiasis based on targeted mass drug administration (MDA) and, in 2017, on supplemental snail control. We compared the current WHO guideline-based strategies from 2012 to an alternative, adaptive decision making framework for control in heterogeneous environments, to estimate their predicted relative effectiveness and time to achievement of defined public health goals.MethodsIn this model-based comparison study, we adapted an established transmission model for Schistosoma infection that couples local human and snail populations and includes aspects of snail ecology and parasite biology. We calibrated the model using data from high-risk, moderate-risk, and lower-risk rural villages in Kenya, and then simulated control via MDA. We compared 2012 WHO guidelines with a modified adaptive strategy that tested a lower-prevalence threshold for MDA and shorter intervals between implementation, evaluation, and modification. We also explored the addition of snail control to this modified strategy. The primary outcomes were the proportion of simulations that achieved the WHO targets in children aged 5–14 years of less than 5% (2020 morbidity control goal) and less than 1% (2025 elimination as a public health problem goal) heavy infection and the mean duration of treatment required to achieve these goals.FindingsIn high-risk communities (80% baseline prevalence), current WHO strategies for MDA were not predicted to achieve morbidity control (<5% prevalence of heavy infections) in 80% of simulations over a 10-year period, whereas the modified adaptive strategy was predicted to achieve this goal in over 50% of simulations within 5 years. In low-risk and moderate-risk communities, current WHO guidelines from 2012 were predicted to achieve morbidity control in most simulations (96% in low-risk and 41% for moderate-risk), although the proposed adaptive strategy reached this goal in a shorter period (mean reduction of 5 years). The model predicted that the addition of snail control to the proposed adaptive strategy would achieve morbidity control in all high-risk communities, and 54% of communities could reach the goal for elimination as a public health problem (<1% heavy infection) within 7 years.InterpretationThe modified adaptive decision making framework is predicted to be more effective than the current WHO guidelines in reaching 2025 public health goals, especially for high-prevalence regions. Modifications in current guidelines could reduce the time and resources needed for countries who are currently working on achieving public health goals against schistosomiasis.FundingUniversity of Georgia Research Foundation, The Bill & Melinda Gates Foundation, and the Medical Scientist Training Program at Stanford University School of Medicine.

An extensive burden of giardiasis associated with intestinal schistosomiasis and anaemia in school children on the shoreline of Lake Albert, Uganda.

Water-borne parasitic diseases associated with poverty still blight the lives of African school children. In Uganda, intestinal schistosomiasis is still common along the shoreline of Lake Albert, despite ongoing control, and co-infection with giardiasis and malaria is poorly described. To shed light on putative interactions between diseases, a prospective cross-sectional parasitological survey was undertaken in five primary schools. Stool samples from 254 school children, aged 5-10 years, were examined by microscopy and rapid diagnostic tests (RDTs), with additional real-time PCR assays for detection of Giardia DNA. A finger-prick blood sample was also taken from each child and tested for malaria, and haemoblobin levels measured. Assocations between diseases and anaemia were assessed. Intestinal schistosomiasis (46.5%), giardiasis (41.6%) and malaria (56.2%) were common, and a quarter of children were anaemic (<115 g/L). Up to 87.0% of children were excreting Giardia DNA and the prevalence of heavy infection by real-time PCR (Ct≤19) was 19.5%, being positively associated with light, moderate and heavy egg-patent schistosomiasis, as well as with anaemia. In this setting, an extensive burden of giardiasis was revealed with heavy intensity infections associated with egg-patent intestinal schistosomiasis and anaemia. To improve child health, greater attention on giardiasis is needed along with exploring joined-up actions across diseases that promote better water hygiene and sanitation measures.

Spatial distribution of intestinal parasitic infections in a Kaingáng indigenous village from Southern Brazil

The spatial distribution of enteroparasitosis in an indigenous village from Paraná was evaluated to identify areas of risk for these infections. A cross-sectional study (from November 2010 to June 2011) was performed using Three Faecal Test® and Kato & Katz method and a questionnaire on housing and hygiene conditions was administered. Local geostatistical analyses were performed to determine the spatial distribution of intestinal parasitic infections. The overall prevalence of enteroparasites was 67.2 % (457/680), and the most prevalent taxa were Ascaris lumbricoides (48.8 %) and Trichuris trichiura (44.7 %). The prevalence of heavy infection by soil-transmitted helminths was 3.6 % and the families lived in houses with an average of 5.1 residents and < 2 bedrooms per household. The average number of species per individual present spatial heterogeneity with the highest values (≥0.8) in areas with high clustering of residences. The visualization of the spatial distribution of intestinal parasites in this indigenous village is an important contribution to determining health risk areas and planning decisions and services.

Analysis of the population-level impact of co-administering ivermectin with albendazole or mebendazole for the control and elimination of Trichuris trichiura

IntroductionSoil-transmitted helminth (STH) infections are predominately controlled by providing children with preventive chemotherapy with either albendazole or mebendazole. However, neither has a high efficacy against Trichuris trichiura. This low efficacy limits the overall effectiveness of the current STH control programmes against T. trichiura. It has been demonstrated that co-administering ivermectin with albendazole or mebendazole significantly increases the efficacy of current treatments, which may increase the overall effectiveness of control programmes. MethodsUsing a STH transmission mathematical model, we evaluated the potential impact of co-administering ivermectin with albendazole or mebendazole to treat T. trichiura within a preventive chemotherapy programme targeting children (2–15year olds). We evaluated the impact in terms of reduction in prevalent infections, mean worm burden, and prevalence of heavy infections. ResultsAlthough the current treatment strategy reduced T. trichiura worm burden and prevalence of heavy infections, due to their poor efficacy the long term impact of preventive chemotherapy for children was smaller compared to the other STH. Co-administering ivermectin increased the projected impact of the preventive chemotherapy programme in terms of all three of the explored metrics, practically in high transmission settings. Furthermore, ivermectin co-administration greatly increased the feasibility of and timeframe for breaking transmission. ConclusionsCo-administering ivermectin notably increased the projected impact of preventive chemotherapy in high transmission settings and increased the feasibility for breaking transmission. This has important implications for control programmes, some of which may be shifting focus from morbidity control to interruption of transmission, and some of which may be logistically unable to provide preventive chemotherapy twice a year as recommended. However, the benefit of co-administering ivermectin is limited by the fact that 2–5year olds are often ineligible to receive treatment.

Impact of Schistosoma haematobium infection on urinary tract pathology, nutritional status and anaemia in school-aged children in two different endemic areas of the Niger River Basin, Mali

The aim of the present study was to contribute to define urinary schistosomiasis-related morbidity indicators and to understand the relationship between infection intensity and disease burden among school-aged children in different endemic areas of Mali. A cross sectional study was undertaken in two different endemic settings: Koulikoro district, along the river and Selingué dam area in the Niger River Basin in order to compare and describe morbidity related to Schistosoma haematobium infection. A total of 667 children aged 7–14 were enrolled in the study. Among these, 333 were from Koulikoro district (175 boys and 158 girls) and 334 from Selingué dam area (169 boys and 165 girls). The overall prevalence of S. haematobium in the two areas was 91.5%; Koulikoro (97.0%) and Selingué (85.9%) and this difference was significant after adjusting for age, sex and clustering within villages. Prevalence of heavy infection (≥50 eggs per 10ml of urine), 57.6% in Koulikoro and 43.8% in Selingué, did not differ significantly after adjusting for age, sex and clustering within villages. The transmission of Schistosoma mansoni was mainly confined to Selingué dam area (12.5%) and was nearly absent in Koulikoro district (1.1%). Blood in urine was the most frequently reported clinical symptom, more common in Koulikoro (76.8%) than in Selingué (57.6%). In a multivariable logistic regression model adjusting for sex, age group, egg intensity category and clustering within villages, Selingué had higher prevalence of macro-haematuria, urinary tract pathology, upper urinary tract pathology and total pathology than Koulikoro, while micro-haematuria did not differ between the two areas. Morbidity measures increased to some extent with egg intensity category, especially micro-haematuria. The results obtained from this study are of importance for planning intervention as for monitoring and evaluation of control in different endemic settings in Mali.

Associations between host migration and the prevalence of a protozoan parasite in natural populations of adult monarch butterflies

Summary1. Monarch butterfliesDanaus plexippus(L.) (Lepidoptera: Nymphalidae) are susceptible to infection by the obligate protozoan parasiteOphryocystis elektroscirrha(McLaughlin and Myers) (Apicomplexa: Neogregarinida). Because monarchs form resident and migratory populations in different parts of the world, this host–parasite system provides the opportunity to examine how variation in parasite prevalence relates to host movement patterns.2. Parasite prevalence was evaluated using 14 790 adult monarchs captured between 1968 and 1997. Comparison of three populations in North America indicated that parasite prevalence is associated negatively with host dispersal distances. A continuously breeding, nonmigratory population in southern Florida showed high prevalence (over 70% heavily infected). The western population migrates moderate distances to overwintering sites on the Pacific Coast and has intermediate prevalence (30% heavily infected). The eastern migratory population, which travels the longest distance to Mexican overwintering sites, has exhibited less than 8% infection throughout the past 30 years.3. Variation in parasite loads within North American migratory populations was investigated to determine whether the prevalence of heavy infection and average parasite loads declined during migration or overwintering. Average parasite loads of summer‐breeding adults in western North America decreased with increasing distance from overwintering sites. This suggests that heavily infected monarchs are less likely to remigrate long distances in spring. No differences in the frequency of heavily infected adults were found among eastern or western North American monarchs throughout the overwintering period, however, suggesting that this parasite does not affect overwintering mortality.4. Changes in the prevalence of monarchs with low parasite loads demonstrate that spore transfer occurs during migration and overwintering, possibly when adult butterflies contact each other as a result of their clustering behaviour.5. This study of geographical and temporal variation inO. elektroscirrhaamong populations ofD. plexippusdemonstrates the potential role of seasonal migration in mediating interactions between hosts and parasites, and suggests several mechanisms through which migratory behaviour may influence parasite prevalence.

The epidemiology of hookworm infection and its contribution to anaemia among pre-school children on the Kenyan coast

Intestinal nematode infections are recognized as a major public health problem, and helminth control is currently being directed towards school-aged children who are known to harbour the heaviest infections and are most likely to suffer from associated morbidity. However, few data are available for the epidemiology of intestinal nematodes in pre-school children in Africa, and the contribution of hookworm infection to the aetiology and severity of anaemia among pre-school children remains poorly understood. This paper investigates the epidemiology of parasitic infections in 460 pre-school children who were part of a larger case-control study of severe malaria in Kilifi on the Kenyan coast. Almost one-third (28·7%) were infected with hookworm, 20·2% with Ascaris lumbricoides and 15·0% with Trichuris trichiura. Infection prevalence of each species rose with age, and the prevalence of heavy infection with hookworm and mean intensity of hookworm were markedly age-dependent. One-third (34·3%) of children had malaria. Overall, 76·3% of children were anaemic (haemoglobin < 110 g/L), with the prevalence decreasing with age. Anaemia was significantly worst in children with heavy hookworm infection (>200 eggs per gram). This relationship held for all ages, both sexes, and was independent of socioeconomic factors. The application of attributable morbidity methods confirmed the contribution of hookworm infection to anaemia.

Predicting the impact of school-based treatment for urinary schistosomiasis given by the Ghana Partnership for Child Development

Mathematical models can be used to predict the impact of interventions to control infectious diseases. In this paper, an epidemiological model is used to predict the impact of chemotherapy of school-age children infected with Schistosoma haematobium, in a programme conducted by the Ghana Partnership for Child Development in the Volta Region, Ghana. Existing data were used to validate the predictions of the model, demonstrating convincingly the ability of the model to make correct predictions. Predictions of trends in mean egg count, infection prevalence and prevalence of heavy infection (>50 eggs/10 mL urine) were then made for the period 1997–1999, and will be compared to the data collected in the programme in the future.

The development of an age structured model for schistosomiasis transmission dynamics and control and its validation for Schistosoma mansoni.

Mathematical models are potentially useful tools to aid in the design of control programmes for parasitic diseases. In this paper, a fully age structured epidemiological model of human schistosomiasis is developed and parameterized, and used to predict trends in infection prevalence, intensity and prevalence of heavy infections over age and time during several rounds of mass and age targeted treatment. The model is validated against data from a Schistosoma mansoni control programme in Kenya.

Epidemiological study of Schistosoma haematobium infection in the coastal area of Kenya. Parasitological baseline data in the Pilot area, Mwachinga.

A cross-sectional epidemiological survey on Schistosoma haematobium infection was carried out in a small community in the coastal area of Kenya. From the 1, 206 registered inhabitants, 853 urine specimens were examined. The overall prevalence and intensity of infection were 68.2 percent and 50.0/hour respectively. Some demographical and geographical differences of infection were analyzed. The profile of age-related distribution showed sexual differences in the prevalence and intensity of infection, the prevalence of heavy infection (>1, 000/hour) and the prevalence of gross hematuria. Those of females are higher than those of males especially after adolescence. This is probably due to the difference in water contact behavior. The marked higher prevalence and intensity of infection were observed among people who lived along the branch of a main river than those who lived along the main river. The difference might be due to the different degree of contamination in the rivers. There was no difference in prevalence and intensity of infection among the three main tribes.