491 research outputs found
Phylogeny and biogeography of African <em>Biomphalaria</em> (Gastropoda: Planorbidae), with emphasis on endemic species of the great East African lakes
No full textFigure 2. Plots of transitions (TS) and transversions (TV) for Biomphalaria relative to the percentage sequence divergence (p-distance). The sliding window analysis for noncoding sequences and codon position for protein coding sequences are given in the insets. A, TS/TV plot of the partial sequence of the mitochondrial 16S gene. Regions with the most variation are identified in the sliding window analysis and correspond to loop regions in the secondary structure. B, TS/TV plot of the total internal transcribed spacer I (ITS1) gene that indicates a possible saturation. The sliding window analysis (inset) illustrates that the variation is not distributed uniformly across the sequence. C, TS/TV plot of the partial sequence of cytochrome oxidase subunit I (COI; primer pair LCO/HCO). The codon position plot is given in the inset. D, TS/TV plot of the partial sequence of COI (primer pair ASMIT 1/2). The codon position plot is given in the inset.Published as part of Jørgensen, Aslak, Kristensen, Thomas K. & Stothard, J. Russell, 2007, Phylogeny and biogeography of African Biomphalaria (Gastropoda: Planorbidae), with emphasis on endemic species of the great East African lakes, pp. 337-349 in Zoological Journal of the Linnean Society 151 (2) on page 341, DOI: 10.1111/j.1096-3642.2007.00330.x, http://zenodo.org/record/542842
An update on female and male genital schistosomiasis and a call to integrate efforts to escalate diagnosis, treatment and awareness in endemic and non-endemic settings: The time is now
No full textThe last decades have brought important insight and updates in the diagnosis, management and immunopathology of female genital schistosomiasis (FGS) and male genital schistosomiasis (MGS). Despite sharing a common parasitic aetiological agent, FGS and MGS have typically been studied separately. Infection with Schistosoma haematobium manifests with gender-specific clinical manifestations and consequences of infection, albeit having a similar pathogenesis within the human genital tract. Schistosoma haematobium is a known urinary bladder carcinogen, but its potential causative role in other types of neoplasia, such as cervical cancer, is not fully understood. Furthermore, the impact of praziquantel treatment on clinical outcomes remains largely underexplored, as is the interplay of FGS/MGS with relevant reproductive tract infections such as HIV and Human Papillomavirus. In non-endemic settings, travel and immigrant health clinics need better guidance to correctly identify and treat FGS and MGS. Our review outlines the latest advances and remaining knowledge gaps in FGS and MGS research. We aim to pave a way forward to formulate more effective control measures and discuss elimination targets. With a growing community awareness in health practitioners, scientists and epidemiologists, alongside the sufferers from these diseases, we aspire to witness a new generation of young women and men free from the downstream disabling manifestations of disease.</p
The long road to schistosomiasis elimination in Zanzibar:a systematic review covering 100 years of research, interventions and control milestones
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Epidemiology and clinical aspects of Strongyloides stercoralis infection in Cambodia
Full text linkBackground: The threadworm Strongyloides stercoralis is endemic in settings where sanitary conditions are poor and where the climate is warm and humid. More than 70 tropical countries in Southeast Asia, Sub-Saharan Africa, West Indies and Latin America are considered as high endemic settings. However, S. stercoralis is also prevalent in subtropical and temperate regions including Australia, Japan, Canada, United States and Europe. The global prevalence of S. stercoralis is heterogeneous. It is believed that about 30 - 100 million people worldwide are infected with S. stercoralis. But the true number and the global burden of infection remain unknown and most probably are today underestimating in many areas of the tropical resource poor countries. The low sensitivity of the currently available diagnostic tools and a scarcity of specialized survey are most important factors for that. Moreover, many epidemiological aspects of S. stercoralis infection are poorly understood or unknown. It is not known in detail where S. stercoralis is endemic, which infection rates and intensities can typically be expected in different settings and populations, and when an individual was infected at first-time and how quickly the re-infection can occur after successful treatment. Epidemiological information on S. stercoralis such as large-scale prevalence, re-infection, risk factors, clinical features and treatment efficacy are unknown in Cambodia and many parts of Southeast Asia.
Aim and objectives: This PhD thesis aimed to understand the importance of S. stercoralis infection in Cambodia by pursuing four main objectives: (i) assess S. stercoralis infection and risk factors, validate diagnostic methods and determine treatment efficacy among schoolchildren, (ii) determine large-scale prevalence and risk factors in two socioeconomic and ecological distinctly different settings, (iii) determine re-infection rates among schoolchildren, and (iv) document clinical aspects of patients with high intensity of S. stercoralis infection in rural communities.
Methods: School- and community-based studies were carried out in four primary schools and 120 villages of three provinces (Kandal, Preah Vihear and Takeo) in Cambodia, from 2009 to 2011. After obtaining the written informed consent from participants, an individual questionnaire was administrated to obtain demographic, risk-perception and behavioral data. The head of household was interviewed with a household questionnaire on socioeconomic indicators of the household such as house type, household assets, latrine and livestock. After the interview, each participant was given a pre-labeled plastic container (ID code, name, sex, age and date) for stool sample collection. In case a multiple stool samples analysis, another stool container was distributed upon collection of the first or second sample. The fecal materials were analyzed by Baermann method and Koga-agar plate (KAP) culture for diagnosing S. stercoralis and Kato-Katz method for helminth co-infections.
Two school-based studies were performed in four primary schools in Kandal province. In 2009, a cross-sectional study was carried out among 458 children, examining three fecal samples per child, to assess risk factors, diagnostic methods and treatment efficacy after three weeks of ivermectin treatment (100?g/kg/day for two days). A two-year cohort study was conducted among 302 schoolchildren from 2009 to 2011, analyzing two stool samples per child, to determine re-infection and risk factors of S. stercoralis.
Two large-scale cross-sectional community-based studies were conducted in 2010 and 2011 to assess infection prevalence and risk factors in two provinces (2396 participants from 60 villages of Preah Vihear province, analyzed two stool samples per participant; and 2861 participants from 60 villages of Takeo province, examined one stool sample per participant). Bayesian kriging was used to predict risk at non-surveyed locations in Preah Vihear province. A case-series study, nested in the survey in Preah Vihear province in 2010, was carried out to document the clinical features of 21 S. stercoralis cases, with high numbers of S. stercoralis larvae in their fecal specimen detected by Baermann technique.
Principal findings: A cross-sectional school-based survey in 2009 found that 24.4% of 458 schoolchildren were infected with S. stercoralis. The prevalence of S. stercoralis infection increased considerably (from 18.6% to 24.4%) when three stool samples were examined. The sensitivity of KAP culture and Baermann technique was 88.4% and 75.0%, respectively. Clinical features such as itchy skin and diarrheal episodes were significantly associated with S. stercoralis infection. Children who reported defecating in latrines were significantly less infected with S. stercoralis than those who did not use latrines (OR: 0.4; 95% CI: 0.2 – 0.6; P<0.001). Almost three-quarters of the infections could have been reduced by proper sanitation (PAR: 0.7; 95% CI: 0.5– 0.9). Ivermectin (200 µg/kg BW, PO, over 2 days) was highly efficacious against S. stercoralis infection, with a cure rate of 98.3% three weeks after treatment.
In Preah Vihear and Takeo provinces, S. stercoralis infection prevalence among general population was 44.7% and 21.0%, respectively. In both areas found that the male participants were significantly more infected than females (P<0.001) in all age classes. In Preah Vihear province, northern Cambodia, S. stercoralis infection statistically increased with age, starting at 31.4% in children less than 6 years to a peak of at 51.2% in participants older than 50 years. Participants defecating in latrines were significantly less infected with S. stercoralis than those who did not use latrine (OR: 0.5; 95% CI: 0.4 - 0.8; P<0.001). S. stercoralis infection exhibited almost no tendency to spatial clustering in this province. Infection risk significantly decreased with increasing rainfall and soil organic carbon content and to increase in lands occupied by rice fields. In Takeo province, southern Cambodia, S. stercoralis infection prevalence reached 14.5% in children under or equal to 5 years and 28.0% in participants aged between 56 and 60 years. Participants who reported having a latrine were statistically less infected with S. stercoralis infection than those who did not possess latrine at home (OR: 0.7; 95% CI: 04 - 0.8; P: 0.003). Muscle pain and urticaria were significantly associated with S. stercoralis infection.
A two-year cohort study among 302 schoolchildren revealed a prevalence rate of 24.2% and 22.5% at baseline (2009) and follow-up (2011), respectively. Almost one-third (31.5%) of 73 treated S. stercoralis cases at baseline were re-infected at follow-up. But, almost 70% of children infected at baseline and treated remained free of re-infection for the period of two years. Children reported having shoes and defecating in toilet were statistically less infected with S. stercoralis than those who did not possess shoes (OR: 0.3; 95% CI: 0.1 – 0.5; P: 0.031) and use latrine (OR: 0.4; 95% CI: 0.2 – 0.9; P<0.001) at follow-up. None of the reported clinical symptom was significantly associated with S. stercoralis infection at follow-up.
Clinical symptoms of 21 S. stercoralis patients with high intensity infection (more than 250 larvae in Baermann test) from Preah Vihear province were documented in 2010. The median age of the patients was 11 years (range: 5 - 67); 23.8% were females. Eleven patients (52.4%) were younger than 16 years. Out of 21 patients, 20 (95.2%), 18 (85.7%) and 14 (66.7%) reported frequent abdominal pain, diarrhea and periods of sensation of itching, respectively, during the previous six months. Five patients (23.8%) reported having experienced urticaria the week preceding the examination. One patient suffered from extended urticaria. Three weeks after ivermectin treatment (200µg/kg BW, single oral dose), most symptoms (diarrhea, abdominal pain and urticaria) almost entirely resolved.
Conclusions: S. stercoralis infection is highly prevalent in rural communities of Cambodia where appropriate diagnosis and treatment do not exist. The re-infection rate of S. stercoralis among schoolchildren after two years of ivermectin treatment is considerable, but more than two-third remains free of infection for at least 2 years. Preschool- and school-aged children are highly affected. Personal hygiene and sanitation including wearing shoes, possession and use of latrines, are significant predictors of S. stercoralis infection. Gastrointestinal and cutaneous symptoms are associated with S. stercoralis infection and resolve almost entirely after ivermectin treatment. Thus, S. stercoralis infection should no longer be neglected in Cambodia and elsewhere in tropical resource poor countries. Access to adequate diagnosis and treatment of S. stercoralis infection is an urgent need in Cambodi
HTLV-I and Strongyloides in Australia: The worm lurking beneath
No full textStrongyloidiasis and HTLV-I (human T-lymphotropic virus-1) are important infections that are endemic in many countries around the world with an estimated 370 million infected with Strongyloides stercoralis alone, and 5–10 million with HTVL-I. Co-infections with these pathogens are associated with significant morbidity and can be fatal. HTLV-I infects T-cells thus causing dysregulation of the immune system which has been linked to dissemination and hyperinfection of S. stercoralis leading to bacterial sepsis which can result in death. Both of these pathogens are endemic in Australia primarily in remote communities in Queensland, the Northern Territory, and Western Australia. Other cases in Australia have occurred in immigrants and refugees, returned travellers, and Australian Defence Force personnel. HTLV-I infection is lifelong with no known cure. Strongyloidiasis is a long-term chronic disease that can remain latent for decades, as shown by infections diagnosed in prisoners of war from World War II and the Vietnam War testing positive decades after they returned from these conflicts. This review aims to shed light on concomitant infections of HTLV-I with S. stercoralis primarily in Australia but in the global context as well
Multidisciplinary studies of schistosomiasis and HIV on the shoreline of Lake Malawi: A longitudinal cohort study of male genital schistosomiasis (MGS) among fishermen in Mangochi District.
Full text linkMale genital schistosomiasis (MGS) is a specific chronic manifestation of schistosomiasis associated with schistosome eggs and related pathologies in the genital system of men inhabiting or visiting endemic areas. Despite description of the first recognised MGS patient by Madden in 1911, the epidemiology, diagnostic testing and case management of MGS are not well described owing to limited research and diminishing focus over several decades. Furthermore, as the human immunodeficiency virus (HIV) epidemic expands across sub-Saharan Africa (SSA), there is renewed interest in MGS owing to plausible but as of yet under-explored interactions with HIV.
To shed new light on MGS, a longitudinal cohort study was conducted among fishermen along the southern shoreline of Lake Malawi, an endemic area in SSA to investigate the prevalence of MGS, its associated knowledge, attitudes and practices (KAP), and determine the potential increase of viral shedding in semen of HIV-positive men with MGS. A systematic review conducted prior to the onset of the research fieldwork describing the MGS epidemiology, clinico-pathological manifestations, diagnostic techniques and treatment outlined and informed the current approach to the body of research presented here.
Fishermen aged 18+ years were recruited into the study after providing informed written consent and individual questionnaires were administered to assess their KAP associated with MGS. Thereafter, participants submitted urine, semen, and blood for point-of-care (POC) field parasitological tests, and later laboratory-based molecular polymerase chain reaction (PCR), and HIV VL analyses. In addition, transabdominal and scrotal ultrasonography to assess the pathological effects of MGS on their genital organs were performed. Praziquantel therapy was provided to all participants, together with the follow-up diagnoses and treatment dates after 1, 3, 6 and 12-months’ intervals.
376 fishermen (320 HIV-negative and 56 HIV-positive on Antiretroviral therapy (ART)) aged between 18 and 70 years (median: 30.0 years), were recruited into the study, and had questionnaires interviews. At baseline, prevalence of UGS (S. haematobium eggs in urine) was 17.1% (n = 210, median: 2.3 per 10 ml, range: 0.1 – 186.0), 3.8% had a positive point-of-care circulating cathodic antigen (POC-CCA) indicative of intestinal S. mansoni infection, while MGS prevalence was 10.4% by semen microscopy (n = 114, median: 5.0, range: 0.1 – 30.0) and 26.5% by real-time PCR (n = 65, Ct value range: 18.8 – 36.6). More participants (66.7%) with schistosome eggs in semen were observed to not have any eggs in their urine. 6.9% of participants (n = 130) were observed to have pathological lesions in their genital organs on ultrasonography. For 15 HIV-MGS cases and 16 HIV-only controls who submitted paired blood and semen samples during the longitudinal study, more cases than controls had detectable and quantifiable VL, which regressed with PZQ. Similarly, the results of the diagnostic tests improved, with negative schistosome egg, real-time PCR in semen and pathological resolution on follow-up.
In conclusion, MGS has been observed, via parasitological, molecular and radiological examinations, to be common in local male inhabitants (fishermen) of endemic areas along the south shoreline of Lake Malawi in the SSA region and shown to respond to standard PZQ treatment. Improving availability and accessibility for all people in these areas to PZQ, diagnostic tools for MGS, and combined HIV and schistosomiasis control interventions are advocated to reduce morbidity and improve the lives and reproductive health of men, their partners and communities in endemic areas
Expansion of lymphatic filariasis transmission assessment surveys (TAS) in Oceania as a pragmatic platform for key insights into the epidemiology of communicable diseases including intestinal parasite infections
Full text linkIntroduction: Lymphatic filariasis (LF) and intestinal parasite infections are most prevalent neglected tropical diseases (NTDs) in Oceania. Since 1999, Pacific Programme to Eliminate Lymphatic Filariasis (PacELF) has successfully addressed critical issues and countries are able to stop mass drug administration (MDA) after a decade of the implementation. Transmission assessment surveys (TAS) is a standard methodology to assess whether MDA has reduced the LF prevalence to levels equal to or below the critical cut-off threshold. The aim of this thesis is to present the successful examples of expanding TAS as a pragmatic platform in providing insights into the epidemiology of the key communicable diseases in Oceania. Method: In Wallis Futuna (WAF), grade 2-5 students for the TAS and grade 4-5 for the hepatitis B virus (HBV) infection prevalence assessment were enrolled. The timeliness of vaccination was defined as being vaccinated no later than 4 weeks in comparison to the recommended immunization schedules. In Fiji, all class 1 and 2 students were targeted in 77, 82, and 50 selected schools for the Western TAS 2, Central TAS 1 and Northern Division TAS 2, where same students of 30, 20, and 20 schools were subsampled ... (continues
Parasitological and malacological surveys reveal urogenital schistosomiasis on Mafia Island, Tanzania to be an imported infection
No full textTo confirm the local endemicity of Schistosoma haematobium on Mafia Island, Tanzania, conjoint parasitological and malacological surveys were undertaken in July 2006 with parasitological investigations supplemented with case-history questionnaires. A total of 238 children (125 girls and 113 boys, mean age of 13.9 years) across 9 primary schools were examined. The prevalence of micro-haematuria and egg-patent infection was 18.1% (CI95=9.6-33.6) and 4.2% (CI95=1.9-7.6), respectively but a strong female bias was observed for micro-haematuria (5.6F:1M) contrasting with a strong male bias for the presence of eggs (1F:4M). All egg-patent infections were of light-intensity (<10eggs/10ml). No clear associations between infection prevalence and local water-contact, by school, were found and all 10 of the egg-positive children had a travel history to the nearby mainland or Zanzibar. Inspection of community diagnostic registers at Kilindoni Hospital revealed a low proportion (<2%) of egg-patent infection for 20,306 samples tested in the 2000-2005 period. A total of 43 freshwater sites, a third of which were previously sampled in 1999 and 2002, were surveyed and 11 species of freshwater mollusc were found. Four species of Bulinus (B. nasutus, B. forskalii, B. barthi and B. sp.) were encountered across 13 sites with B. nasutus restricted to 3 of these towards the north of the island. No collected snail was observed to shed schistosome cercariae. Further characterisation of B. nasutus and S. haematobium included infection challenge on two occasions, with miracidia obtained from egg-patent children from Mafia and Unguja islands as well as DNA barcoding of snails and schistosomes. B. nasutus was shown refractory to infection. With the substantial travel to and from Mafia, the refractory nature of local snails and evidence from DNA barcoding in schistosomes and snails, we conclude that urogenital schistosomiasis is an imported infection
Use of sentinel snails for the detection of Schistosoma haematobium transmission on Zanzibar and observations on transmission patterns
No full textUrogenital schistosomiasis is an important public health issue in Zanzibar. Transmission of the parasite to the human population is related to the distribution of the intermediate snail host, Bulinus globosus. We measured B. globosus abundance and Schistosoma haematobium prevalence within snails in a series of naturally occurring populations and compared prevalence detected by observing cercarial shedding for patent infections, and by PCR using DraI repeat. A total of 2146 B. globosus were collected throughout the study period from 2003 to 2007; of these 85 (3.96%) were shedding cercariae. The levels of infection detected by PCR were consistently higher (40-100 percent). Levels of exposure to miracidia in the field were measured using sentinel snails. B. globosus (a susceptible host) and B. nasutus (a non-susceptible host) were placed in cages at transmission sites for 72h to observe rates of penetration by miracidia. Both B. globosus and B. nasutus tested positive for S. haematobium by PCR (up to 24% infected) indicating frequent contamination of the waterbodies with S. haematobium miracidia. The use of sentinel snails coupled with PCR diagnostics could be a sensitive tool for mapping and monitoring transmission of schistosomiasis in areas of low prevalence
Molecular characterization of cryptic and sympatric lymnaeid species from the Galba/Fossaria group in Mendoza Province, Northern Patagonia, Argentina
Full text linkBackground: Freshwater lymnaeid snails can act as the intermediate hosts for trematode parasites such as the liver fluke Fasciola hepatica, that cause significant economic and biomedical burden worldwide, particularly through bovine fascioliasis. Transmission potential is tightly coupled to local compatibility with snail hosts, so accurate identification of lymnaeid species is crucial for understanding disease risk, especially when invasive species are encountered. Mendoza Province, in Argentina, is a center of livestock production and also an area of endemic fascioliasis transmission. However, the distribution of lymnaeid species in the region is not well known. Methods: This study examined lymnaeid snails from seven localities in the Department of Malarguë, Mendoza Province, using morphological and molecular analyses and also describing ecological variables associated with snail presence. Results: While morphological characters identified two species of lymnaeid, Galba truncatula and G. viatrix, molecular data revealed a third, cryptic species, G. neotropica, which was sympatric with G. viatrix. G. truncatula was exclusively found in high altitude (>1900 meters above sea level [masl]) sites, whereas mixed G. neotropica/G. viatrix localities were at middle elevations (1300-1900 masl), and G. viatrix was found alone at the lowest altitude sites (<1300 masl). Phylogenetic analysis using two mitochondrial markers revealed G. neotropica and G. viatrix to be closely related, and given their morphological similarities, their validities as separate taxonomic entities should be questioned. Conclusions: This study highlights the need of a robust taxonomic framework for the identification of lymnaeid snails, incorporating molecular, morphological and ecological variables while avoiding nomenclature redundancy. As the three species observed here, including one alien invasive species, are considered hosts of varying susceptibility to Fasciola parasites, and given the economic importance of fascioliasis for livestock production, this research has critical importance for the ultimate aim of controlling disease transmission.Fil: Standley, Claire J.. University of Princeton; Estados UnidosFil: Prepelitchi, Lucila. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ecología, Genética y Evolución. Unidad de Ecología de Reservorios y Vectores de Parásitos; ArgentinaFil: Pietrokovsky, Silvia Monica. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires; ArgentinaFil: Issia, Laura Andrea. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ecología, Genética y Evolución. Unidad de Ecología de Reservorios y Vectores de Parásitos; ArgentinaFil: Stothard, J. Russell. Liverpool School of Tropical Medicine; Reino UnidoFil: Wisnivesky, Maria Cristina. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ecología, Genética y Evolución. Unidad de Ecología de Reservorios y Vectores de Parásitos; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Ecología, Genética y Evolución de Buenos Aires; Argentin
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