Browsing by Author "Villena, Isabelle"
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- Risk factors for sporadic cryptosporidiosis: a systematic review and meta-analysisPublication . Kooh, Pauline; Thébault, Anne; Cadavez, Vasco; Gonzales-Barron, Ursula; Villena, IsabelleCryptosporidium spp. is an important cause of gastrointestinal disease worldwide, responsible for 69 million cases of illness in 2016. Information on the sources and transmission pathways of human cryptosporidiosis results mainly from outbreak investigations. A systematic review and a meta-analysis of case-control and cohort studies were performed to determine the main risk factors associated with sporadic cryptosporidiosis. Suitable scientific articles were identified through a systematic literature search and subjected to a methodological quality assessment. From each study, odds ratio (OR) measures were extracted or calculated, as well as study characteristics such as population type, design, type of model and risk factor hierarchy. Mixed-effects meta-analysis models were adjusted by population type to appropriate data partitions. From 1985 identified references, the quality assessment stage was passed by 57 cohort and case-control studies focusing on sporadic cryptosporidiosis. The eligible studies were conducted between 1983 and 2016 and provided 568 OR categorized for meta-analysis. This meta-analysis identified travel, immunocompromising conditions, contact with infected humans, waterborne transmission (contact with recreational waters, wastewater, and consumption of untreated drinking water), contact with animals and food consumption as the relevant risk factors for sporadic cryptosporidiosis. With regards to food exposures, consumption of meat, dairy products (raw milk) and dishes consumed outside home were found significantly associated with cryptosporidiosis. The consumption of poorly washed fruits and vegetables significantly increases ORs. This meta-analysis reveals that some potential sources of Cryptosporidium such as shellfish or vegetables are under-investigated. Future case-control studies for sporadic cryptosporidiosis should include population at risk, and investigate other potential sources in relation to the genotype and the subtype of Cryptosporidium spp.
- Risk factors for sporadic giardiasis: a systematic review and meta-analysis: meta-analysis of risk factors associated with sporadic giardiasisPublication . Thébault, Anne; Favennec, Loic; Kooh, Pauline; Cadavez, Vasco; Gonzales-Barron, Ursula; Villena, IsabelleGiardia duodenalis is an important source of gastroenteritis worldwide. Endemic cases have been described in developing and industrialized countries. We analyzed risk factors for sporadic giardiasis by a systematic review and a meta-analysis of the literature. From 72 studies, contact with an infected person, lack of personal hygiene, and attending a child daycare center were identified as risk factors in children and adults. Feco-oral transmission was significantly associated with exposure to human sewage/waste water, untreated drinking water and recreational waters. Travel abroad was a risk factor in industrialized countries. No handwashing before eating or preparing food, eating unwashed vegetables, or composite food were significant risk factors. Breastfeeding was a protective factor in developing countries. Interestingly, contact with pets was found as a significant risk factor in children in this meta-analysis. This could be explored in future studies with the comparison of the Giardia assemblage isolated from humans and pets. In the future, it would be interesting to investigate more precisely the type of water, vegetable, and whenever possible the method of preparation/treatment. Environmental and epidemiological investigations of specific risk factors by assemblages and types of Giardia spp. should be further studied. Finally, host factors in relationship with the severity and sequelae of giardiasis deserve future research.
- Risk factors for sporadic toxoplasmosis: a systematic review and meta-analysisPublication . Thebault, Anne; Kooh, Pauline; Cadavez, Vasco; Gonzales-Barron, Ursula; Villena, IsabelleToxoplasmosis is considered as the most prevalent parasitic zoonotic infection worldwide. The parasitic cycle is mostly known, but the relative contribution of different sources and pathways of transmission was not previously studied by a meta-analysis. A systematic review and a meta-analysis of case-control, cohort, and cross-sectional studies were performed to determine the main risk factors associated with sporadic Toxoplasma infection. Suitable scientific articles were identified through a systematic literature search and subjected to a methodological quality assessment. Mixed-effects meta-analysis models were adjusted by population type – children, mixed population, and pregnant women – to appropriate data partitions. 187 primary studies passed the quality assessment stage, investigating risk factors for sporadic infection with Toxoplasma gondii conducted between 1983 and 2016. Cases were defined by serology. The meta-analysis of Toxoplasma sporadic infections revealed the significance of transmission by environmental factors such as contact with soil and contact with animals, in particular cats. The consumption of raw or undercooked meat and unwashed vegetables significantly increased the odds of acquiring the disease. Shellfish and raw milk were identified as significant sources of toxoplasmosis. Almost all meat categories were identified as risk factors: pork, poultry, beef, processed meat, lamb, and game meat. Contaminated drinking water may play a role in the acquisition of infection. Moreover, the lack of hygiene in preparing food was identified as a risk factor. A significant risk factor for pregnant women is traveling abroad. Lastly, blood transfusion (in pregnant women) and immunocompromised conditions were found associated with positive serology. The broad definition of exposures and the use of serology for the case definition are the main limitations for the interpretation of the results of this meta-analysis. The transmission pathways require further investigations using longitudinal studies and subtyping approaches.