Potential Risk Factors Associated with Human Cystic Echinococcosis: Systematic Review and Meta-analysis

15 páginas, 2 figuras, 2 tablasBackground Scientific literature on cystic echinococcosis (CE) reporting data on risk factors is limited and to the best of our knowledge, no global evaluation of human CE risk factors has to date been performed. This systematic review (SR) summarizes available data on statistically relevant potential risk factors (PRFs) associated with human CE.Methodology/Principal Findings Database searches identified 1,367 papers, of which thirty-seven were eligible for inclusion. Of these, eight and twenty-nine were case-control and cross-sectional studies, respectively. Among the eligible papers, twenty-one were included in the meta-analyses. Pooled odds ratio (OR) were used as a measure of effect and separately analysed for the two study designs. PRFs derived from case-control studies that were significantly associated with higher odds of outcome were ªdog free to roamº (OR 5.23; 95% CI 2.45±11.14), ªfeeding dogs with visceraº (OR 4.69; 95% CI 3.02±7.29), ªslaughter at homeº (OR 4.67; 95% CI 2.02±10.78) or at ªslaughterhousesº (OR 2.7; 95% CI 1.15±6.3), ªdog ownershipº (OR 3.54; 95% CI 1.27±9.85), ªliving in rural areasº (OR 1.83; 95% CI 1.16±2.9) and ªlow incomeº (OR 1.68; 95% CI 1.02±2.76). Statistically significant PRFs from cross-sectional studies with higher odds of outcome were ªage >16 yearsº (OR 6.08; 95% CI 4.05±9.13), ªliving in rural areasº (OR 2.26; 95% CI 1.41±3.61), ªbeing femaleº (OR 1.38; 95% CI 1.06± 1.8) and ªdog ownershipº (OR 1.37; 95% CI 1.01±1.86). Conclusions/Significance Living in endemic rural areas, in which free roaming dogs have access to offal and being a dog-owner, seem to be among the most significant PRFs for acquiring this parasiticinfection. Results of data analysed here may contribute to our understanding of the PRFs for CE and may potentially be useful in planning community interventions aimed at controlling CE in endemic areas.Conclusions/Significance Living in endemic rural areas, in which free roaming dogs have access to offal and being a dog-owner, seem to be among the most significant PRFs for acquiring this parasiticinfection. Results of data analysed here may contribute to our understanding of the PRFs for CE and may potentially be useful in planning community interventions aimed at controlling CE in endemic areas.This research received funding from the European Community's Seventh Framework Programme under the grant agreement 602051 (Project HERACLES: Human cystic Echinococcosis ReseArch in CentraL and Eastern Societies; http://www.heracles-fp7.eu/).Peer reviewe

Dog ownership, dog behaviour and transmission of Echinococcus spp. in the Alay Valley, southern Kyrgyzstan

Echinococcosis is a re-emerging zoonotic disease in Kyrgyzstan, and the incidence of human infection has increased substantially since the collapse of the Soviet Union in 1991. Domestic dogs are hosts of Echinococcus spp. and play an important role in the transmission of these parasites. The demography, ecology and behaviour of dogs are therefore relevant in studying Echinococcus spp. transmission. Dog demographics, roles of dogs, dog movements and faecal environmental contamination were assessed in four rural communities in the Alay Valley, southern Kyrgyzstan. Arecoline purge data revealed for the first time that E. granulosus, E. canadensis and E. multilocularis were present in domestic dogs in the Alay Valley. Surveys revealed that many households had dogs and that dogs played various roles in the communities, as pets, guard dogs or sheep dogs. Almost all dogs were free to roam, and GPS data revealed that many moved outside their communities, thus being able to scavenge offal and consume rodents. Faecal environmental contamination was high, presenting a significant infection risk to the local communitie

Epidemiological Study of Cystic Echinococcosis in Sheep, Cattle and Goats in Erbil Province

Cystic echinococcosis (CE) or hydatid cyst (HC) caused by the larval stage of the tapeworm Echinococcus granulosus continues to be a substantial cause of morbidity and mortality in many parts of the world. Since Kurdistan region is considered as endemic area, an epidemiological study was conducted to investigate the occurrence of CE isolated from sheep, cattle and goats from July 2013 to June 2014. The total rate of infection was 11.17(457/4092), with the highest rate (9.07%) in sheep and the lowest (0.54%) in goats. Regarding the sex of the infected animals, female showed slightly a higher rate than males (5.99% versus 5.18%) which statistically non-significant (P>0.05). Among the three intermediate host sheep showed the highest rate of infection (14.51%) regarding the sex females of sheep and cattle showed higher rate of infection versus males (27.36 and 20.35 versus 9.37 and 3.86). Furthermore, the highest incidence of CE in sheep, cattle and goats were found among the age group over three years (18.75, 5.41 and 1.69%, respectively), while the lowest rate was noted in the age groups less than one year (3.96 and 0.25%, o.33, respectively). On the other hand, sheep showed high rate of infection throughout the year with peaks during May to July which were 19.44%, 17.59 and 18.14%,respectively. This was followed by cattle and goats (11.67% and 5.26%) in April and December, respectively. Regarding the size, the higher numbers of small sized cysts were found in the liver (98/175), while the highest numbers of large sized cysts were found in both liver and lung which were 69/165. The liver and lungs appeared to be the site of predilection, since highest rate of infection was reported in these organs. Regarding the fertility of CE, the highest was in sheep (87.6%), followed by goats (77.27%) and then the cattle (40.63%)

The geographical distribution and prevalence of Echinococcus multilocularis in animals in the European Union and adjacent countries : a systematic review and meta-analysis

Background This study aimed to provide a systematic review on the geographical distribution of Echinococcus multilocularis in definitive and intermediate hosts in the European Union (EU) and adjacent countries (AC). The relative importance of the different host species in the life-cycle of this parasite was highlighted and gaps in our knowledge regarding these hosts were identified. Methods Six databases were searched for primary research studies published from 1900 to 2015. From a total of 2,805 identified scientific papers, 244 publications were used for meta-analyses. Results Studies in 21 countries reported the presence of E. multilocularis in red foxes, with the following pooled prevalence (PP): low (≤ 1 %; Denmark, Slovenia and Sweden); medium (> 1 % to 10 %; Czech Republic, Estonia, France, Germany, Latvia, Lithuania, Poland, Slovakia, Liechtenstein and Switzerland). Studies from Finland, Ireland, the United Kingdom and Norway reported the absence of E. multilocularis in red foxes. However, E. multilocularis was detected in Arctic foxes from the Arctic Archipelago of Svalbard in Norway. Conclusions Raccoon dogs (PP 2.2 %), golden jackals (PP 4.7 %) and wolves (PP 1.4 %) showed a higher E. multilocularis PP than dogs (PP 0.3 %) and cats (PP 0.5 %). High E. multilocularis PP in raccoon dogs and golden jackals correlated with high PP in foxes. For intermediate hosts (IHs), muskrats (PP 4.2 %) and arvicolids (PP 6.0 %) showed similar E. multilocularis PP as sylvatic definitive hosts (DHs), excluding foxes. Nutrias (PP 1.0 %) and murids (PP 1.1 %) could play a role in the life-cycle of E. multilocularis in areas with medium to high PP in red foxes. In areas with low PP in foxes, no other DH was found infected with E. multilocularis. When fox E. multilocularis PP was >3 %, raccoon dogs and golden jackals could play a similar role as foxes. In areas with high E. multilocularis fox PP, the wolf emerged as a potentially important DH. Dogs and cats could be irrelevant in the life-cycle of the parasite in Europe, although dogs could be important for parasite introduction into non-endemic areas. Muskrats and arvicolids are important IHs. Swine, insectivores, murids and nutrias seem to play a minor or no role in the life-cycle of the parasite within the EU and ACs

Genetic and migratory evidence for sympatric spawning of tropical pacific eels from Vanuatu

The spawning areas of tropical anguillid eels in the South Pacific are poorly known, and more information about their life histories is needed to facilitate conservation. We genetically characterized 83 out of 84 eels caught on Gaua Island (Vanuatu) and tagged 8 eels with pop-up satellite transmitters. Based on morphological evidence, 32 eels were identified as Anguilla marmorata, 45 as A. megastoma and 7 as A. obscura. Thirteen of these eels possessed a mitochondrial DNA sequence (control region, 527 bp) or nuclear haplotype (GTH2b, 268 bp) conflicting with their species designation. These individuals also had multi-locus genotypes (6 microsatellite loci) intermediate between the species, and 9 of these eels further possessed heterozygote genotypes at species-diagnostic nuclear single nucleotide polymorphisms (SNPs). We classified these individuals as possibly admixed between A. marmorata and A. megastoma. One A. marmorata and one A. megastoma migrated 634 and 874 km, respectively, towards the border between the South Equatorial Current and the South Equatorial Counter Current. Both species descended from around 200 m depth at night to 750 m during the day. Lunar cycle affected the upper limit of migration depths of both species. The tags remained attached for 3 and 5 mo and surfaced <300 km from the pop-up location of a previously tagged A. marmorata. A salinity maximum at the pop-up locations corresponding to the upper nighttime eel migration depths may serve as a seamark of the spawning area. The similar pop-up locations of both species and the evidence for admixture suggest that these tropical eels share a sympatric spawning area

Independent evaluation of a canine Echinococcosis control programme in Hobukesar County, Xinjiang, China

The Xinjiang Uyghur Autonomous Region in northwest China is one of the world's most important foci for cystic echinococcosis. Domestic dogs are the main source for human infection, and previous studies in Xinjiang have found a canine Echinococcus spp. coproELISA prevalence of between 36% and 41%. In 2010 the Chinese National Echinococcosis Control Programme was implemented in Xinjiang, and includes regular dosing of domestic dogs with praziquantel. Six communities in Hobukesar County, northwest Xinjiang were assessed in relation to the impact of this control programme through dog necropsies, dog Echinococcus spp. coproantigen surveys based on Lot Quality Assurance Sampling (LQAS) and dog owner questionnaires. We found that 42.1% of necropsied dogs were infected with Echinococcus granulosus, and coproELISA prevalences were between 15% and 70% in the communities. Although approximately half of all dog owners reported dosing their dogs within the 12 months prior to sampling, coproELISA prevalence remained high. Regular praziquantel dosing of owned dogs in remote and semi-nomadic communities such as those in Hobukesar County is logistically very difficult and additional measures should be considered to reduce canine echinococcosis

Echinococcus granulosus : epidemiology and state-of-the-art of diagnostics in animals

Diagnosis and detection of Echinococcus granulosus (sensu lato) infection in animals is a prerequisite for epidemiological studies and surveillance of echinococcosis in endemic, re-emergent or emergent transmission zones. Advances in diagnostic approaches for definitive hosts and livestock, however, have not progressed equally over the last 20 years. Development of laboratory based diagnostics for canids using coproantigen ELISA and also coproPCR, have had a huge impact on epidemiological studies and more recently on surveillance during hydatid control programmes. In contrast, diagnosis of cystic echinococcosis (CE) in livestock still relies largely on conventional post-mortem inspection, despite a relatively low diagnostic sensitivity especially in early infections, as current serodiagnostics do not provide a sufficiently specific and sensitive practical pre-mortem alternative. As a result, testing of dog faecal samples by coproantigen ELISA, often combined with mass ultrasound screening programmes for human CE, has been the preferred approach for monitoring and surveillance in resource-poor endemic areas and during control schemes. In this article we review the current options and approaches for diagnosis of E. granulosus infection in definitive and animal intermediate hosts (including applications in non-domesticated species) and make conclusions and recommendations for further improvements in diagnosis for use in epidemiological studies and surveillance schemes

Echinococcus multilocularis and Echinococcus shiquicus in a small mammal community on the eastern Tibetan Plateau : host species composition, molecular prevalence, and epidemiological implications

Background The eastern part of the Tibetan Plateau is now recognized as an endemic region with the highest reported human infection rates in the world of human alveolar echinococcosis (AE) caused by Echinococcus multilocularis. Existing epidemiological studies on AE have mainly focused on the synanthropic environment, while basic parasitological and ecological aspects in wildlife host species remain largely unknown, especially for small mammal hosts. Therefore, we examined small mammal host species composition, occurrence, and the prevalence of both E. multilocularis and E. shiquicus in Shiqu County (Sichuan Province, China), eastern Tibetan Plateau. Results In total, 346 small mammals from five rodent and one pika species were trapped from four randomly set 0.25 ha square plots. Two vole species, Lasiopodomys fuscus (n = 144) and Microtus limnophilus (n = 44), and the plateau pika (Ochotona curzoniae) (n = 135), were the three most-dominant species trapped. Although protoscoleces of E. multilocularis and E. shiquicus were only observed in L. fuscus and O. curzoniae, respectively, cox1 and nad1 gene DNA of E. shiquicus was detected in all the small mammal species except for Neodon irene, whereas E. multilocularis was detected in the three most-dominant species. The overall molecular prevalence of Echinococcus species was 5.8 (95% CI: 3.3–8.2%) ~ 10.7% (95% CI: 7.4–14.0%) (the conservative prevalence to the maximum prevalence with 95% CI in parentheses), whereas for E. multilocularis it was 4.3 (95% CI: 2.2–6.5%) ~ 6.7% (95% CI: 4.0–9.3%), and 1.5 (95% CI: 0.2–2.7%) ~ 4.1% (95% CI: 2.0–6.1%) for E. shiquicus. The prevalence of both E. multilocularis and E. shiquicus, was significantly higher in rodents (mainly voles) than in pikas. Phylogenetic analyses revealed that Echinococcus haplotypes of cox1 from small mammal hosts were actively involved in the sylvatic and anthropogenic transmission cycles of E. multilocularis in the eastern Tibetan Plateau. Conclusions In contrast to previous studies, the current results indicated that rodent species, rather than pikas, are probably more important natural intermediate hosts of E. multilocularis and E. shiquicus in the eastern Tibetan Plateau. Thus, understanding interspecific dynamics between rodents and pikas is essential to studies of the echinococcosis transmission mechanism and human echinococcosis prevention in local communities. Keywords: Echinococcus multilocularis, E. shiquicus, Small mammal Prevalence, Tibetan Platea

Human and Canine Echinococcosis Infection in Informal, Unlicensed Abattoirs in Lima, Peru

Echinococcus granulosus infections are a major public health problem in livestock-raising regions around the world. The life cycle of this tapeworm is sustained between dogs (definitive host, canine echinococcosis), and herbivores (intermediary host, cystic hydatid disease). Humans may also develop cystic hydatid disease. Echinococcosis is endemic in rural areas of Peru; nevertheless, its presence or the extension of the problem in urban areas is basically unknown. Migration into Lima, an 8-million habitant's metropolis, creates peripheral areas where animals brought from endemic areas are slaughtered without veterinary supervision. We identified eight informal, unlicensed abattoirs in a peripheral district of Lima and performed a cross-sectional study in to assess the prevalence of canine echinococcosis, evaluated by coproELISA followed by PCR evaluation and arecoline purge. Eight of 22 dogs (36%) were positive to coproELISA, and four (18%) were confirmed to be infected with E. granulosus tapeworms either by PCR or direct observation (purge). Later evaluation of the human population living in these abattoirs using abdominal ultrasound, chest X-rays and serology, found 3 out of 32 (9.3%) subjects with echinococcal cysts in the liver (two viable, one calcified), one of whom had also lung involvement and a strongly positive antibody response. Autochthonous transmission of E. granulosus is present in Lima. Informal, unlicensed abattoirs may be sources of infection to neighbouring people in this urban environment