Effect Of Seasonal Rainfall And Other Environmental Changes, On Snail Density And Infection Rates With Schistosoma mansoni Fifteen Years After The Last Snails\' Study In Kigungu, Entebbe, Uganda

Background: The last study on snail population density in relation to rainfall pattern in Kigungu canoe landing and recreational sites on Lake Victoria shore was earlier carried out about fifteen years ago. This study also reviewed the influence of other environmental factors on the snails\' infection rate. Objective: To reassess the density dynamic of Biomphalaria (B) choanomphala and Biomphalaria (B) pfeifferi, which act as the intermediate host for S. mansoni and Bulinus (B) globosus, and Bulinus (B) tropicus, which act as intermediate host for S. haematobium. Design: Retrospective study. Setting: Busy canoe landing sites along Lake Victoria in Kigungu fishing village were selected for the snail sampling. Results: Nine thousand one hundred and ninety four B. choanomphala were collected over the study period. The numbers of B. choanomphala collected in each year was 4742 (51.6%) and 4452 (48.4%) in 2004 and 2005 respectively. Of the 4742 B.Choanomphala collected in 2004, 82 (1.7%) shed human cercariae and 329 (6.7%) shed non-human cercariae. Whereas in 2005, out of 4452 B. choanomphala collected 302 (6.85%) shed non-human cercariae and 82 (1.8%) shed human cercariae. Similarly, 4173 B. pfeifferi were also collected in the same period. Out of which 2224 (53.3%) were collected in 2004 and 1949 (46.7%) in 2005. For B. pfeifferi, 42 (1.9%) out of 2224 snails collected in 2004 shed human cercariae and 246 (11.1%) shed non-human cercariae. While in 2005, 33 out of 1949 snails (1.7%) shed human cercariae and 159 (8.2%) shed non-human cercariae. Other snails of medical importance collected included 292 B. globosus and 3094 B. tropicus. None of the Bulinus spp. collected shed any human cercariae but 37 (2.1%) and 30 (2.3%) B. tropicus shed non-human cercariae in 2004 and 2005 respectively. In 2004 and 2005, the area received, 1729mm and 1959mm of rainfall respectively. The mean rainfall during the year was 144.05 mm and 163.3 mm in 2004 and 2005 respectively. There was a negative correlation between rainfalls and snail density dynamic. Conclusion: We have found in this study that in spite of the bush clearing of the papyrus swamps which originally was the major habitats for B. choanomphala, B. pfeifferi and the Bulinus spp the intermediate host for schistosome at all canoe landing sites at Kigungu, these snails are still present. Moreover, that their population density dynamic and infection rate are inversely proportional to the rainfall pattern. East African Medical Journal Vol. 85 (11) 2008: pp. 556-56

Profiling lifetime episodes of upper gastrointestinal bleeding among patients from rural Sub-Saharan Africa where schistosoma mansoni is endemic

© Christopher Kenneth Opio et al.Introduction: Severe chronic hepatic schistosomiasis is a common cause of episodes upper gastrointestinal bleeding (UGIB) in sub-Saharan Africa (SSA). However, there is paucity of data on clinical epidemiology of episodes of UGIB from rural Africa despite on going public health interventions to control and eliminate schistosomiasis. Methods: Through a cross sectional study we profiled lifetime episodes of upper gastrointestinal bleeding and associated factors at a rural primary health facility in sub-Saharan Africa were schistosomiasis is endemic. The main outcome was number of lifetime episodes of UGIB analyzed as count data. Results: From 107 enrolled participants, 323 lifetime episodes of UGIB were reported. Fifty-seven percent experienced ≥ 2 lifetime episodes of UGIB. Ninety-four percent had severe chronic hepatic schistosomiasis and 80% esophageal varices. Alcohol use and viral hepatitis was infrequent. Eighty-eight percent were previously treated with praziquantel and 70% had a history of blood transfusion. No patient had ever had an endoscopy or treatment for prevention of recurrent variceal bleeding. Multivariable analysis identified a cluster of eight clinical factor variables (age ≥ 40, female sex, history of blood transfusion, abdominal collaterals, esophageal varices, pattern x periportal fibrosis, anemia, and thrombocytopenia) significantly associated (P-value < 0.05) with increased probability of experiencing two or more lifetime episodes of UGIB in our study. Conclusion: Upper gastrointestinal bleeding is a common health problem in this part of rural SSA where schistosomiasis is endemic. The clinical profile described is unique and is important for improved case management, and for future research

Changes in IgE- and antigen-dependent histamine-release in peripheral blood of Schistosoma mansoni-infected Ugandan fishermen after treatment with praziquantel.

BACKGROUND: Parasite-specific IgE levels correlate with human resistance to reinfection with Schistosoma spp. after chemotherapy. Although the role of eosinophils in schistosomiasis has been the focus of a great deal of important research, the involvement of other Fcepsilon receptor-bearing cells, such as mast cells and basophils, has not been investigated in relation to human immunity to schistosomes. Chemotherapy with praziquantel (PZQ) kills schistosomes living in an in vivo blood environment rich in IgE, eosinophils and basophils. This releases parasite Ags that have the potential to cross-link cell-bound IgE. However, systemic hypersensitivity reactions are not induced by treatment. Here, we describe the effects of schistosomiasis, and its treatment, on human basophil function by following changes in total cellular histamine and in vitro histamine-release induced by schistosome Ags or anti-IgE, in blood samples from infected Ugandan fishermen, who are continuously exposed to S. mansoni infection, before and 1-day and 21-days after PZQ treatment. RESULTS: There was a significant increase in the total cellular histamine in blood samples at 1-day post-treatment, followed by a very significant further increase by 21-days post-treatment. In vitro histamine-release induced by S. mansoni egg (SEA) or worm (SWA) Ags or anti-IgE antibody, was significantly reduced 1-day post-treatment. The degree of this reduction correlated with pre-treatment infection intensity. Twenty-1-days post-treatment, SEA-induced histamine-release was still significantly lower than at pretreatment. Histamine-release was not correlated to plasma concentrations of total or parasite-specific IgE, nor to specific IgG4 plasma concentrations. CONCLUSION: The biology of human blood basophils is modulated by S. mansoni infection and praziquantel treatment. Infection intensity-dependent suppression of basophil histamine-release, histamine-dependent resistance to infection, and similarities with allergen desensitisation are discussed as possible explanations of these observations

Multimorbidity healthcare expenditure in Belgium: a 4-year analysis (COMORB study)

Background: The complex management of health needs in multimorbid patients, alongside limited cost data, presents challenges in developing cost-effective patient-care pathways. We estimated the costs of managing 171 dyads and 969 triads in Belgium, taking into account the influence of morbidity interactions on costs. Methods: We followed a retrospective longitudinal study design, using the linked Belgian Health Interview Survey 2018 and the administrative claim database 2017–2020 hosted by the Intermutualistic Agency. We included people aged 15 and older, who had complete profiles (N = 9753). Applying a system costing perspective, the average annual direct cost per person per dyad/triad was presented in 2022 Euro and comprised mainly direct medical costs. We developed mixed models to analyse the impact of single chronic conditions, dyads and triads on healthcare costs, considering two-/three-way interactions within dyads/triads, key cost determinants and clustering at the household level. Results: People with multimorbidity constituted nearly half of the study population and their total healthcare cost constituted around three quarters of the healthcare cost of the study population. The most common dyad, arthropathies + dorsopathies, with a 14% prevalence rate, accounted for 11% of the total national health expenditure. The most frequent triad, arthropathies + dorsopathies + hypertension, with a 5% prevalence rate, contributed 5%. The average annual direct costs per person with dyad and triad were €3515 (95% CI 3093–3937) and €4592 (95% CI 3920–5264), respectively. Dyads and triads associated with cancer, diabetes, chronic fatigue, and genitourinary problems incurred the highest costs. In most cases, the cost associated with multimorbidity was lower or not substantially different from the combined cost of the same conditions observed in separate patients. Conclusion: Prevalent morbidity combinations, rather than high-cost ones, made a greater contribution to total national health expenditure. Our study contributes to the sparse evidence on this topic globally and in Europe, with the aim of improving cost-effective care for patients with diverse needs

Drug Resistance in Eukaryotic Microorganisms

Eukaryotic microbial pathogens are major contributors to illness and death globally. Although much of their impact can be controlled by drug therapy as with prokaryotic microorganisms, the emergence of drug resistance has threatened these treatment efforts. Here, we discuss the challenges posed by eukaryotic microbial pathogens and how these are similar to, or differ from, the challenges of prokaryotic antibiotic resistance. The therapies used for several major eukaryotic microorganisms are then detailed, and the mechanisms that they have evolved to overcome these therapies are described. The rapid emergence of resistance and the restricted pipeline of new drug therapies pose considerable risks to global health and are particularly acute in the developing world. Nonetheless, we detail how the integration of new technology, biological understanding, epidemiology and evolutionary analysis can help sustain existing therapies, anticipate the emergence of resistance or optimize the deployment of new therapies

Modelling the spatial and seasonal distribution of suitable habitats of schistosomiasis intermediate host snails using Maxent in Ndumo area, KwaZulu-Natal Province, South Africa

Abstract Background Schistosomiasis is a snail-borne disease endemic in sub-Saharan Africa transmitted by freshwater snails. The distribution of schistosomiasis coincides with that of the intermediate hosts as determined by climatic and environmental factors. The aim of this paper was to model the spatial and seasonal distribution of suitable habitats for Bulinus globosus and Biomphalaria pfeifferi snail species (intermediate hosts for Schistosoma haematobium and Schistosoma mansoni, respectively) in the Ndumo area of uMkhanyakude district, South Africa. Methods Maximum Entropy (Maxent) modelling technique was used to predict the distribution of suitable habitats for B. globosus and B. pfeifferi using presence-only datasets with ≥ 5 and ≤ 12 sampling points in different seasons. Precipitation, maximum and minimum temperatures, Normalised Difference Vegetation Index (NDVI), Normalised Difference Water Index (NDWI), pH, slope and Enhanced Vegetation Index (EVI) were the background variables in the Maxent models. The models were validated using the area under the curve (AUC) and omission rate. Results The predicted suitable habitats for intermediate snail hosts varied with seasons. The AUC for models in all seasons ranged from 0.71 to 1 and the prediction rates were between 0.8 and 0.9. Although B. globosus was found at more localities in the Ndumo area, there was also evidence of cohabiting with B. pfiefferi at some of the locations. NDWI had significant contribution to the models in all seasons. Conclusion The Maxent model is robust in snail habitat suitability modelling even with small dataset of presence-only sampling sites. Application of the methods and design used in this study may be useful in developing a control and management programme for schistosomiasis in the Ndumo area

Spatial analysis of the distribution of intestinal nematode infections in Uganda.

The spatial epidemiology of intestinal nematodes in Uganda was investigated using generalized additive models and geostatistical methods. The prevalence of Ascaris lumbricoides and Trichuris trichiura was unevenly distributed in the country with prevalence greatest in southwest Uganda whereas hookworm was more homogeneously distributed. A. lumbricoides and T. Trichiura prevalence were nonlinearly related to satellite sensor-based estimates of land surface temperature; hookworm was nonlinearly associated with rainfall. Semivariogram analysis indicated that T. trichiura prevalence exhibited no spatial structure and that A. lumbricoides exhibited some spatial dependency at small spatial distances, once large-scale, mainly environmental, trends had been removed. In contrast, there was much more spatial structure in hookworm prevalence although the underlying factors are at present unclear. The implications of the results are discussed in relation to parasite spatial epidemiology and the prediction of infection distributions

THE EFFECT OF SEASONAL RAINFALL AND OTHER ENVIRONMENTAL CHANGES, ON SNAIL DENSITY AND INFECTION RATES WITH SCHISTOSOMA MANSONI FIFTEEN YEARS AFTER THE LAST SNAILS’ STUDY IN KIGUNGU, ENTEBBE, UGANDA

Background: The last study on snail population density in relation to rainfall pattern in Kigungu canoe landing and recreational sites on Lake Victoria shore was earlier carried out about a fi fteen years ago. This study also reviewed the infl uence of other environmental factors on the snails’ infection rate.Objective: To reassess the density dynamic of Biomphalaria (B) choanomphala and Biomphalaria (B) pfeifferi, which act as the intermediate host for S. mansoni and Bulinus (B) globosus, and Bulinus (B) tropicus, which act as intermediate host for S. haematobium.Design: Retrospective study.Setting: Busy canoe landing sites along Lake Victoria in Kigungu fi shing village were selected for the snail sampling.Results: Nine thousand one hundred and ninety four B. choanomphala were collected over the study period. The numbers of B. choanomphala collected in each year was 4742 (51.6%) and 4452 (48.4%) in 2004 and 2005 respectively. Of the 4742 B.Choanomphala collected in 2004,82 (1.7%) shed human cercariae and 329 (6.7%) shed non-human cercariae. Whereas in 2005, out of 4452 B. choanomphala collected 302 (6.85&lt;%) shednon-human cercariae and 82 (1.8%) shed human cercariae. Similarly, 4173 B. pfeifferi were also collected in the same period. Out of which 2224 (53.3%)) were collected in 2004 and 1949 (46.7%) in 2005. For B. pfeifferi, 42 (1.9%) out of 2224 snails collected in 2004 shed human cercariae and 246 (11.1(%) shed non-human cercariae. While in 2005, 33 outof 1949 snails (1.7%) shed human ccrcariae and 159 (8.2%) shed  non-human cercariae. Other snails of medical importance collected included 292 B. globosus and 3094 B. tropicus. None of the Bulinus spp. collected shed any human cercariae but 37 (2.1 %) and 30 (2.3%) B. tropicus shed non-human cercariae in 2004 and 2005 respectively. In 2004 and 2005, the area received, 1729mm and 1959mm of rainfall respectively. The meanrainfall during the year was 144.05 mm and 163.3 mm in 2004 and 2005 respectively. There was a negative correlation between rainfalls and snail density dynamic.Conclusion: We have found in this study that in spite of the bush clearing of the papyrus swamps which originally was the major habitats for B. choanomphala, B. pfeifferi and the Bulinus spp the intermediate host for schistosome at all canoe landing sites at Kigungu, these snails are still present. Moreover, that their population density dynamic and infection rate are inversely proportional to the rainfall pattern