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PLoS Neglected Tropical Diseases Aug 2019In South Asia, hundreds of millions of people are infected with soil-transmitted helminths (Ascaris lumbricoides, hookworm, and Trichuris trichiura). However,...
BACKGROUND
In South Asia, hundreds of millions of people are infected with soil-transmitted helminths (Ascaris lumbricoides, hookworm, and Trichuris trichiura). However, high-resolution risk profiles and the estimated number of people infected have yet to be determined. In turn, such information will assist control programs to identify priority areas for allocation of scarce resource for the control of soil-transmitted helminth infection.
METHODOLOGY
We pursued a systematic review to identify prevalence surveys pertaining to soil-transmitted helminth infections in four mainland countries (i.e., Bangladesh, India, Nepal, and Pakistan) of South Asia. PubMed and ISI Web of Science were searched from inception to April 25, 2019, without restriction of language, study design, and survey date. We utilized Bayesian geostatistical models to identify environmental and socioeconomic predictors, and to estimate infection risk at high spatial resolution across the study region.
PRINCIPAL FINDINGS
A total of 536, 490, and 410 georeferenced surveys were identified for A. lumbricoides, hookworm, and T. trichiura, respectively. We estimate that 361 million people (95% Bayesian credible interval (BCI) 331-395 million), approximately one-quarter of the South Asia population, was infected with at least one soil-transmitted helminth species in 2015. A. lumbricoides was the predominant species. Moderate to high prevalence (>20%) of any soil-transmitted helminth infection was predicted in the northeastern part and some northern areas of the study region, as well as the southern coastal areas of India. The annual treatment needs for the school-age population requiring preventive chemotherapy was estimated at 165 million doses (95% BCI: 146-185 million).
CONCLUSIONS/SIGNIFICANCE
Our risk maps provide an overview of the geographic distribution of soil-transmitted helminth infection in four mainland countries of South Asia and highlight the need for up-to-date surveys to accurately evaluate the disease burden in the region.
Topics: Ancylostomatoidea; Animals; Ascariasis; Ascaris lumbricoides; Asia; Bangladesh; Bayes Theorem; Databases, Factual; Helminthiasis; Helminths; Hookworm Infections; Humans; India; Nepal; Pakistan; Prevalence; Risk Factors; Socioeconomic Factors; Soil; Trichuriasis; Trichuris
PubMed: 31398200
DOI: 10.1371/journal.pntd.0007580 -
Anisakis sensitization in different population groups and public health impact: A systematic review.PloS One 2018Anisakis simplex spp. sensitization rates have increased worldwide, with a significant impact on health-care systems. To date, no clear-cut diagnostic criteria and...
Anisakis simplex spp. sensitization rates have increased worldwide, with a significant impact on health-care systems. To date, no clear-cut diagnostic criteria and laboratory algorithm have been established, so anisakiasis still represents an under-reported health problem whose clinical manifestations, when present, mimic the much more common allergic and digestive disorders. Aim of the study was to systematically review the available literature on the prevalence of sensitization against Anisakis in the general population and in specific population groups, taking into account the impact of the different available diagnostic techniques on the epidemiological data. Following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement, relevant papers reporting Anisakis sensitization epidemiological data were found covering a period ranging from 1996 to February 2017. Overall, 41 studies comprising 31,701 participants from eleven countries were included in the qualitative synthesis. General asymptomatic population resulted sensitized to Anisakis in 0.4 to 27.4% of cases detected by means of indirect ELISA or ImmunoCAP specific IgE detection, and between 6.6% and 19.6% of the samples by Skin prick test (SPT). Occupationally exposed workers (fishermen, fishmongers and workers of fish-processing industries) documented specific IgE between 11.7% and 50% of cases, whereas SPT positivity ranged between 8% and 46.4%. Symptomatic allergic patients to any kind of allergen were found to be positive to Anisakis specific IgE detection between 0.0% (in children with mastocytosis) to 81.3% (among adults with shellfish allergy). Results highlighted that hypersensitivity prevalence estimates varied widely according to geographical area, characteristics of the population studied, diagnostic criteria and laboratory assays. Further studies are needed to overcome the documented misdiagnosis by improving the diagnostic approach and, consequently, providing more affordable estimates in order to address public health interventions on populations at high risk of exposure to Anisakis and to tailor health services related to specific groups.
Topics: Animals; Anisakis; Antibodies, Helminth; Enzyme-Linked Immunosorbent Assay; Humans; Hypersensitivity; Occupational Exposure
PubMed: 30235242
DOI: 10.1371/journal.pone.0203671 -
Transactions of the Royal Society of... Dec 2018We performed a systematic review and meta-analysis on observational studies to evaluate the possible associations between Toxocara species seropositivity and allergic... (Meta-Analysis)
Meta-Analysis
We performed a systematic review and meta-analysis on observational studies to evaluate the possible associations between Toxocara species seropositivity and allergic skin disorders (ASDs). We searched the MEDLINE, ScienceDirect, Scopus, Web of Science and Google Scholar databases to 15 May 2018 to identify the relevant studies. We used a random effects meta-analysis model to generate the pooled odds ratio (OR) and 95% confidence intervals (CIs). Fifteen studies, including eight studies with a case-control design (735 patients and 1342 controls) and seven studies with a cross-sectional design (a total of 4804 participants, 1302 individuals with ASDs and 3502 without ASDs), were included in the meta-analysis. We found an increased risk for ASDs in individuals with Toxocara seropositivity (OR 1.75 [95% CI 1.16 to 2.64]). Subanalysis showed that Toxocara seropositivity was significantly associated with urticaria (OR 2.97 [95% CI 1.53 to 5.76]), however, it was not significantly associated with atopy (OR 1.08 [95% CI 0.55 to 2.15]) and eczema (OR 1.62 [95% CI 0.95 to 2.78]). Moreover, the pooled ORs were 2.34 (95% CI 1.32 to 4.15) and 1.27 (95% CI 0.69 to 2.35) for case-control and cross-sectional studies, respectively. The results of our study support hypotheses regarding the existence of a positive relationship between Toxocara infection and allergic disorders, although this association should be further investigated by longitudinal and mechanism studies.
Topics: Allergens; Animals; Case-Control Studies; Cross-Sectional Studies; Humans; Hypersensitivity, Immediate; Skin Diseases, Infectious; Toxocara; Toxocariasis
PubMed: 30184239
DOI: 10.1093/trstmh/try094 -
Environmental Pollution (Barking, Essex... Nov 2018Toxocariasis is a neglected tropical disease of humans. Although many studies have indicated or shown that environmental contamination with Toxocara species eggs is a... (Meta-Analysis)
Meta-Analysis Review
Toxocariasis is a neglected tropical disease of humans. Although many studies have indicated or shown that environmental contamination with Toxocara species eggs is a major risk factor for toxocariasis in humans, there has been no comprehensive analysis of published data or information. Here, we conducted the first systematic review and meta-analysis of current literature to assess the global prevalence of Toxocara eggs in public places (including beaches, parks and playgrounds). We conducted searches of the PubMed, Embase, Scopus and Science Direct databases for relevant studies published until 20 April 2018, and assessed the prevalence rates of Toxocara eggs in public places. We used the random effects model to calculate pooled prevalence estimates, with 95% confidence intervals (CIs), and analysed data in relation to WHO geographical regions. Subgroup analysis and meta-regressions regarding the geographical and environmental variables were also performed. Of 2384 publications identified, 109 studies that tested 42,797 soil samples in 40 countries were included in the meta-analysis. The pooled global prevalence of Toxocara eggs in public places was 21% (95% CI, 16-27%; 13,895/42,797). The estimated prevalence rates in the different WHO regions ranged from 13% to 35%: Western Pacific (35%; 95% CI, 15-58%), Africa (27%; 95% CI, 11-47%), South America (25%; 95% CI, 13-33%), South-East Asia (21%; 95% CI, 3-49%), Middle East and North Africa (18%; 95% CI, 11-24%), Europe (18%; 95% CI, 14-22%), and North and Central Americas (13%; 95% CI, 8-23%). A high prevalence was significantly associated with high geographical longitude (P = 0.04), low latitude (P = 0.02) and high relative environmental humidity (P = 0.04). This meta-analysis of data from published records indicates that public places are often heavily contaminated with eggs of Toxocara. This finding calls for measures to reduce the potential risk of infection and disease in humans.
Topics: Animals; Environmental Microbiology; Environmental Monitoring; Parasite Egg Count; Soil; Soil Pollutants; Toxocara
PubMed: 30142562
DOI: 10.1016/j.envpol.2018.07.087 -
PLoS Neglected Tropical Diseases Jul 2018To gain further insight on the association between human toxocariasis and epilepsy in light of the new evidence in the last years. (Meta-Analysis)
Meta-Analysis Review
OBJECTIVE
To gain further insight on the association between human toxocariasis and epilepsy in light of the new evidence in the last years.
METHODS
A systematic review was conducted without date and language restriction in the following electronic databases: MEDLINE (PubMed), Ingenta Connect, Science Direct (Elsevier), RefDoc, Scopus, HighWire, Scielo and the database of the Institute of Neuroepidemiology and Tropical Neurology of the Limoges University (IENT). Two investigators independently conducted the search up to November 2017. A pooled odds ratio (OR) was estimated using a random effects model. Meta-regression was conducted to investigate potential sources of heterogeneity.
RESULTS
Database search produced 204 publications. Eleven case-control studies were included that were carried out in 13 countries worldwide. A total number of 4740 subjects were considered (2159 people with epilepsy and 2581 people without epilepsy). The overall pooled OR was 1.69 (95% CI 1.42-2.01) for the association between epilepsy and Toxocara spp. seropositivity. A positive association was constantly reported in the restricted analysis (WB as confirmatory or diagnostic test, younger population, and population-based studies). Meta-regression showed no statistically significant association between covariates and outcome.
CONCLUSION
The updated meta-analysis provides epidemiological evidence of a positive association between Toxocara seropositivity and epilepsy. New surveys supported the association, mainly population-based studies. On this basis, health strategies to reduce the impact of Toxocara spp are strongly advised. Further research should be performed to understand the physiopathological mechanisms of toxocara-associated epileptogenesis.
Topics: Animals; Epilepsy; Humans; Toxocara; Toxocariasis
PubMed: 30028858
DOI: 10.1371/journal.pntd.0006665 -
Acta Tropica Jun 2018Asthma is one of the most common chronic respiratory disease worldwide, with a negative impact on quality of life and socio-economic status of patients. There are some... (Meta-Analysis)
Meta-Analysis Review
Asthma is one of the most common chronic respiratory disease worldwide, with a negative impact on quality of life and socio-economic status of patients. There are some evidences to suggest that Toxocara infection is a neglected risk factor for childhood asthma. We performed a systematic review and meta-analysis to further understanding of this relationship. Five databases include PubMed, Science Direct, Scopus, Web of Science (ISI), and Google scholar were searched (up to October 2017) to identify the relevant studies. We used random-effects meta-analysis model to estimate the pooled odds ratio (OR) and 95% confidence intervals (CI). Heterogeneity was assessed with the Q-test and I statistic. A total of 17 studies including 11 studies with case-control design (1139 patients and 1023 controls) and six studies with cross-sectional design (a total of 5469 participants, 872 asthmatics, and 4597 non-asthmatics children) met the eligibility criteria. An increased risk for asthma was observed in children with Toxocara infection seropositivity (OR, 1.91; 95% CI, 1.47-2.47). In sub-group analysis, the pooled ORs were (OR, 2.13; 95% CI, 1.43-3.15) and (OR, 1.73; 95% CI, 1.23-2.44) for case-control and cross-sectional studies, respectively. Moreover, considering to specific IgE seropositivity, a pooled OR of 2.36 (95% CI, 0.93-5.98) was observed. In conclusion, this meta-analysis revealed that children infected with Toxocara spp. are more likely to have asthma compared to non-infected children. More studies (especially longitudinal studies) are needed to further investigate the impact of Toxocara spp. infection on the onset or development of asthma.
Topics: Animals; Asthma; Case-Control Studies; Child; Cross-Sectional Studies; Female; Humans; Male; Risk Factors; Toxocara; Toxocariasis
PubMed: 29573999
DOI: 10.1016/j.actatropica.2018.03.022 -
PLoS Neglected Tropical Diseases Nov 2017Human excreta is a low cost source of nutrients vital to plant growth, but also a source of pathogens transmissible to people and animals. We investigated the... (Meta-Analysis)
Meta-Analysis Review
Human excreta is a low cost source of nutrients vital to plant growth, but also a source of pathogens transmissible to people and animals. We investigated the cost-savings and infection risk of soil transmitted helminths (STHs) in four scenarios where farmers used either inorganic fertilizer or fresh/composted human excreta supplemented by inorganic fertilizer to meet the nutrient requirements of rice paddies in the Red River Delta, Vietnam. Our study included two main components: 1) a risk estimate of STH infection for farmers who handle fresh excreta, determined by systematic review and meta-analysis; and 2) a cost estimate of fertilizing rice paddies, determined by nutrient assessment of excreta, a retailer survey of inorganic fertilizer costs, and a literature review to identify region-specific inputs. Our findings suggest that farmers who reuse fresh excreta are 1.24 (95% CI: 1.13-1.37, p-value<0.001) times more likely to be infected with any STH than those who do not handle excreta or who compost appropriately, and that risk varies by STH type (Ascaris lumbricoides RR = 1.17, 95% CI = 0.87-1.58, p-value = 0.29; Hookworm RR = 1.02, 95% CI = 0.50-2.06, p-value = 0.96; Trichuris trichiura RR = 1.38, 95% CI = 0.79-2.42, p-value = 0.26). Average cost-savings were highest for farmers using fresh excreta (847,000 VND) followed by those who composted for 6 months as recommended by the WHO (312,000 VND) and those who composted for a shorter time (5 months) with lime supplementation (37,000 VND/yr); however, this study did not assess healthcare costs of treating acute or chronic STH infections in the target group. Our study provides evidence that farmers in the Red River Delta are able to use a renewable and locally available resource to their economic advantage, while minimizing the risk of STH infection.
Topics: Agriculture; Ancylostomatoidea; Animals; Ascariasis; Ascaris lumbricoides; Body Fluids; Cost-Benefit Analysis; Feces; Hookworm Infections; Humans; Linear Models; Soil; Trichuriasis; Trichuris; Vietnam
PubMed: 29176840
DOI: 10.1371/journal.pntd.0006088 -
Travel Medicine and Infectious Disease 2017Toxocariasis is a globally distributed zoonosis. The most important definitive hosts are dogs, whereas humans serve as paratenic hosts. Transmission to humans occurs by... (Review)
Review
BACKGROUND
Toxocariasis is a globally distributed zoonosis. The most important definitive hosts are dogs, whereas humans serve as paratenic hosts. Transmission to humans occurs by accidental ingestion of eggs, e.g. by consumption of contaminated fruits or vegetables. Although exposure to Toxocara is usually considered as relatively benign, it is implicated in a range of neurological, ophthalmologic and other organ-specific conditions, some of them with grave consequences. This review provides an overview on the epidemiology, presentation and risk factors of exposure to Toxocara in Africa.
METHODS
A systematic search was performed for studies published after January 1st, 1990, in English, French, Portuguese, Spanish, Dutch or German. The review was prepared according to PRISMA guidelines. Studies on toxocariasis in human populations and contamination in human environments were included.
RESULTS
Sixty-five papers were included. Antibodies against Toxocara spp. in humans were found to be very common across Africa. Severe manifestations have been reported mainly from North Africa. Environmental contamination including soil, vegetables and fruits sold on markets was demonstrated in various locations in Africa.
CONCLUSIONS
Exposure to Toxocara is prevalent across the African continent. However, the complication frequency, the impact of the condition on the individual and the public health relevance of this zoonosis, and the economic impact have never been systematically evaluated.
Topics: Africa; Animals; Environment; Food Parasitology; Humans; Prevalence; Risk Factors; Toxocara; Toxocariasis
PubMed: 29037977
DOI: 10.1016/j.tmaid.2017.10.009 -
Lancet (London, England) Jan 2017Soil-transmitted helminth infections are a major global health issue, causing substantial morbidity in the world's poorest populations. Regular delivery of anthelmintic... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
Soil-transmitted helminth infections are a major global health issue, causing substantial morbidity in the world's poorest populations. Regular delivery of anthelmintic drugs is the mainstay for global soil-transmitted helminth control. Deworming campaigns are often targeted to school-aged children, who are at high risk of soil-transmitted-helminth-associated morbidity. However, findings from modelling studies suggest that deworming campaigns should be expanded community-wide for effective control of soil-transmitted helminth transmission. We aimed to do a systematic review and meta-analysis to compare the effect of mass (community-wide) and targeted (children only) anthelmintic delivery strategies on soil-transmitted helminth prevalence in school-aged children.
METHODS
In this systematic review and meta-analysis, we searched MEDLINE, Embase, and Web of Science for articles published on or before Nov 5, 2015, reporting soil-transmitted helminth prevalence before and after distribution of albendazole or mebendazole, either targeted to children or delivered to the whole community. We excluded studies in which drug delivery was restricted to infected individuals or to a subset of the community or school, or if follow-up time was less than 3 months or greater than 18 months after drug delivery. We extracted data on study year, country, drug administration strategy, drug dose, number of deworming rounds, treatment coverage, diagnostic method, follow-up interval, and soil-transmitted helminth prevalence before and after treatment. We used inverse variance weighted generalised linear models, with prevalence reduction as the outcome variable, to examine the effect of mass versus targeted drug administration, as well as baseline prevalence, number of drug doses, and follow-up time. This study is registered with PROSPERO, number CRD42016026929.
FINDINGS
Of 10 538 studies identified, 56 studies were eligible for the systematic review and 38 of these were included in meta-analysis. Results of the regression models showed that mass deworming led to a significantly greater reduction in prevalence in children than targeted deworming, for both hookworm (odds ratio 4·6, 95% CI 1·8-11·6; p=0·0020) and Ascaris lumbricoides (16·4, 2·1-125·8; p=0·0092), with no effect seen for Trichuris trichiura. There was significant heterogeneity across studies; for targeted studies I was 97% for A lumbricoides and hookworm, and 96% for T trichiura, and for mass studies, I was 89% for A lumbricoides, 49% for hookworm, and 66% for T trichiura.
INTERPRETATION
The results of this meta-analysis suggest that expanding deworming programmes community-wide is likely to reduce the prevalence of soil-transmitted helminths in the high-risk group of school-aged children, which could lead to improved morbidity outcomes. These findings are in support of recent calls for re-evaluation of global soil-transmitted helminth control guidelines.
FUNDING
None.
Topics: Adolescent; Ancylostomatoidea; Animals; Anthelmintics; Ascaris lumbricoides; Child; Child, Preschool; Communicable Disease Control; Helminthiasis; Humans; Soil; Trichuris
PubMed: 27979381
DOI: 10.1016/S0140-6736(16)32123-7 -
PLoS Neglected Tropical Diseases May 2016Soil-transmitted helminths (STH) have acute and chronic manifestations, and can result in lifetime morbidity. Disease burden is difficult to quantify, yet quantitative... (Meta-Analysis)
Meta-Analysis Review
BACKGROUND
Soil-transmitted helminths (STH) have acute and chronic manifestations, and can result in lifetime morbidity. Disease burden is difficult to quantify, yet quantitative evidence is required to justify large-scale deworming programmes. A recent Cochrane systematic review, which influences Global Burden of Disease (GBD) estimates for STH, has again called into question the evidence for deworming benefit on morbidity due to STH. In this narrative review, we investigate in detail what the shortfalls in evidence are.
METHODOLOGY/PRINCIPAL FINDINGS
We systematically reviewed recent literature that used direct measures to investigate morbidity from STH and we critically appraised systematic reviews, particularly the most recent Cochrane systematic review investigating deworming impact on morbidity. We included six systematic reviews and meta-analyses, 36 literature reviews, 44 experimental or observational studies, and five case series. We highlight where evidence is insufficient and where research needs to be directed to strengthen morbidity evidence, ideally to prove benefits of deworming.
CONCLUSIONS/SIGNIFICANCE
Overall, the Cochrane systematic review and recent studies indicate major shortfalls in evidence for direct morbidity. However, it is questionable whether the systematic review methodology should be applied to STH due to heterogeneity of the prevalence of different species in each setting. Urgent investment in studies powered to detect direct morbidity effects due to STH is required.
Topics: Anemia; Animals; Anthelmintics; Ascariasis; Ascaris lumbricoides; Chronic Disease; Cost of Illness; Helminthiasis; Humans; Prevalence; Soil
PubMed: 27196100
DOI: 10.1371/journal.pntd.0004566