Life by the river: neglected worm infection in Western Siberia and pitfalls of a one-size-fits-all control approach

Co-created community contracts support biosecurity changes in a region where African swine fever is endemic – Part II: Implementation of biosecurity measures

Smallholder subsistence pig production is common in Uganda and African swine fever (ASF) is endemic in the country, with its spread driven by human activities along the smallholder value chain. Previous research in the study area has revealed that many stakeholders are aware of how ASF is spread, its prevention and control, and have a generally positive attitude towards biosecurity. Despite this, even basic biosecurity is largely lacking. Costs, as well as a lack of adaptation to the local context, culture and traditions have been identified as factors hindering biosecurity implementation. Community engagement and local ownership of disease problems are increasingly recognised as important for improving disease prevention and control. The objective of this study was to investigate the capacity of participatory action at community level with broad inclusion of stakeholders to improve biosecurity in the smallholder pig value chain. Specific attention was paid to participants' perceptions and experiences of implementing the biosecurity measures included in their co-created community contracts. The study was conducted in Northern Uganda in villages purposively selected on the basis of previous occurrences of ASF. In each village, farmers and traders were also purposively selected. At a first meeting, basic information about ASF was shared and participants presented with a list of biosecurity measures adapted for farmers and traders respectively. Participants discussed each measure in farmer and trader subgroups, decided on the measures to implement for one year, and signed a community contract to this effect. The following year, interviews were again undertaken and implementation support given. Interview data were coded and thematically analysed. Each subgroup chose a minimum of three and a maximum of nine measures, with wide variations between villages in their selection of measures. At the follow-ups, none of the subgroups had fully implemented what had been agreed in their contract, but all had changed some of their biosecurity routines. Some frequently recommended biosecurity measures, such as not borrowing breeding boars, were not considered feasible. Relatively simple and cheap biosecurity measures were rejected for reasons of cost, highlighting the participants' general level of poverty and the relevance of poverty as a specific factor governing disease control results. The participatory methodology allowing for discussions, co-creation and the option to refuse measures seemed to facilitate the implementation of measures that had initially been thought to be controversial. The broad community approach was deemed to be positive for strengthening community identity, cooperation and implementation.

Co-created community contracts support biosecurity changes in a region where African swine fever is endemic - Part I: The methodology

In Northern Uganda more people live in poverty than elsewhere in the country. Small-scale pig-keeping is common and African swine fever (ASF) is endemic, spreading along the smallholder value chain. Biosecurity measures remain the only way to prevent and control the spread of ASF in this context. Previous research in the study area has shown that many stakeholders are aware of ASF, how it is spread and methods for prevention and control, but biosecurity implementation remains limited. Participatory approaches have been suggested in order to increase community engagement in relation to animal disease control, ensuring that disease prevention or control actions are guided by local people's priorities and the promotion of local ownership of disease control. The objective of this study was to investigate the capacity of participatory action at community level with a broad inclusion of stakeholders to initiate change and greater stakeholder ownership to improve biosecurity in the smallholder pig value chain. Specific attention was paid to the feasibility of co-created community contracts for this purpose. The study was carried out in Northern Uganda in six purposively selected villages and included both farmers and traders. Centred on co-created community contracts on biosecurity, the study comprised repeated group discussions, semi-structured and structured group and individual interviews, as well as field observations. At the first meeting, participants were presented with suggested biosecurity measures adapted for farmers and traders respectively. Participants discussed each measure, agreed which ones to implement for one year, and co-created a community contract to this effect. During the study period, repeated interviews were undertaken and implementation support was provided. Interview data was coded and thematically analysed. Great diversity was observed between communities with regard to which and how many measures were selected, illustrating heterogeneity in the possibilities of biosecurity implementation and the complexity of livelihood challenges. The methodology appeared to be effective at instigating change, with all the communities changing some of their biosecurity behaviour during the study period. The intensified communication and cooperation around pigs in the communities reinforced the sense of group identity and the capacity-building offered at the first meeting supported implementation and appeared to be more important than the physical contract. Participants reported feeling empowered and described how they shared their knowledge, educated their peers and acted as catalysts for wider biosecurity change in their communities. These are promising results and indicate a positive attitude to both the agreed measures and the methodology.

Exploring the hurdles that remain for control of African swine fever in smallholder farming settings

To honour the 100 years anniversary of the first publication about African swine fever (ASF) a webinar with a particular focus on disease control in the smallholder sector was organized. This article is based on the webinar, summarizing the early history of ASF research, reflecting on the current global disease situation and bringing forward some suggestions that could contribute towards achieving control of ASF. The first description of ASF by R. Eustace Montgomery in 1921 laid the foundations for what we know about the disease today. Subsequent research confirmed its association with warthogs and soft ticks of the Ornithodoros moubata complex. During the latter half of the 21st century, exponential growth of pig production in Africa has led to a change in the ASF-epidemiology pattern. It is now dominated by a cycle involving domestic pigs and pork with virus spread driven by people. In 2007, a global ASF epidemic started, reaching large parts of Europe, Asia and the Americas. In Europe, this epidemic has primarily affected wild boar. In Asia, wild boar, smallholders and industrialized pig farms have been affected with impact on local, national and international pig value chains. Globally and historically, domestic pigs in smallholder settings are most frequently affected and the main driver of ASF virus transmission. Awaiting a safe and efficacious vaccine, we need to continue focus on other measures, such as biosecurity, for controlling the disease. However, smallholders face specific challenges linked to poverty and other structural factors in implementing biosecurity measures that can prevent spread. Improving biosecurity in the smallholder sector thus remains an important tool for preventing and controlling ASF. In this regard, interdisciplinary research can help to find new ways to promote safe practices, facilitate understanding and embrace smallholders' perspectives, engage stakeholders and adjust prevention and control policies to improve implementation.

The impact of Opisthorchis felineus infection and praziquantel treatment on the intestinal microbiota in children

The presence of some species of helminths is associated with changes in host microbiota composition and diversity, which varies widely depending on the infecting helminth species and other factors. We conducted a prospective case-control study to evaluate the gut microbiota in children with Opisthorchis felineus infection (n=50) before and after anthelmintic treatment and in uninfected children (n=49) in the endemic region. A total of 99 children and adolescents aged between 7 and 18 years were enrolled to the study. Helminth infection was assessed before and at 3 months after treatment with praziquantel. A complex examination for each participant was performed in the study, including an assessment of the clinical symptoms and an intestinal microbiota survey by 16S rRNA gene sequencing of stool samples. There was no change in alpha diversity between O. felineus-infected and control groups. We found significant changes in the abundances of bacterial taxa at different taxonomic levels between the infected and uninfected individuals. Enterobacteriaceae family was more abundant in infected participants compared to uninfected children. On the genus level, O. felineus-infected participants' microbiota showed higher levels of Lachnospira, Escherichia-Shigella, Bacteroides, Eubacterium eligens group, Ruminiclostridium 6, Barnesiella, Oscillibacter, Faecalitalea and Anaerosporobacter and reduction of Blautia, Lachnospiraceae FCS020 and Eubacterium hallii group in comparison with the uninfected individuals. Following praziquantel therapy, there were significant differences in abundances of some microorganisms, including an increase of Faecalibacterium and decrease of Megasphaera, Roseburia. Enterobacteriaceae and Escherichia abundances were decreased up to the control group values. Our results highlight the importance of the host-parasite-microbiota interactions for the community health in the endemic regions.

Abundance of Opisthorchis felineus Metacercariae in cyprinid fish in the middle Ob River basin (Tomsk region, Russia)

Infection with the liver fluke, Opisthorchis felineus, caused by the consumption of infected raw or undercooked cyprinid fish is common in humans and carnivores in the middle Ob River basin (Tomsk region, Russia) and can lead to diseases in humans. The goal of this study was the status of fish infection with O. felineus metacercariae in order to assess the role of fish in the infection of the human population in the middle Ob River basin.

Of the 14 Cyprinidae species recorded in the middle Ob River basin, we examined 6 cyprinid species for prevalence and intensity of infection with O. felineus metacercariae. Five of these species (Leuciscus idus, Leuciscus leuciscus, Rutilus rutilus, Abramis brama, and Carassius gibelio) are of commercial value, while the common bleak is an object of amateur fishing. In addition, we conducted a survey of the fish consumption habits as part of a community-based cross-sectional study in the rural Shegarsky district, Tomsk region, Russian Federation.

O. felineus metacercariae were observed in muscles of all examined species except for the Prussian carp. The ide is the main infection source in the Ob River (prevalence of infection, 100%, and intensity, 50.5 metacercariae per fish) and the common dace in the Tom River (91.1% and 12.7 metacercariae). Although the two alien species (bream and common bleak) are susceptible to infection with O. felineus metacercariae, the prevalence of infection in these fish and in the roach did not exceed 3%. The prevalence and intensity of infection in fish increased with age and size. The infection characteristics of fish in different water flows were different. The cyprinid species account on average for 69.8% of the commercial fish harvested in the Tomsk region. According to epidemiological survey, among 600 participants, 87.5% (n = 525) of respondents consumed river fish, with the most popular fish being cyprinids including Prussian carp, dace, ide and bream, followed by pike and perch.

Thus, the epizootological state of the water flows in the middle Ob River basin is adverse with respect to opisthorchiasis, as indicated by high infection rates of liver fluke metacercariae in ide and common dace, which are abundant species of high commercial value. An extremely high prevalence of infection suggests a strong transmission cycle with a high rate of infection from infected humans and/or animal reservoir hosts to snails and fish. In addition to treating humans, there should be a strong focus on identifying these potential reservoir hosts to reduce subsequent infection in humans. Furthermore, since the intensity of infection in humans is determined by the presence of fish species such as ide and dace in the diet, they should be included in a dietary change campaign by eliminating the consumption of raw fish.

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Commercial cyprinid species play the key role in maintaining opisthorchiasis foci.

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The ide and common dace are the main source of human and animal infection.

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Measures to control Opisthorchis felineus should target these two species of fish.

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The invasion of fish increases with their age and size.

Foodborne zoonotic parasites of the family Opisthorchiidae

Several foodborne zoonotic trematodes of the family Opisthorchiidae have been reported to infect people, specifically two genera, Clonorchis and Opisthorchis. Three species Clonorchis sinensis, Opisthorchis felineus and Opisthorchis viverrini are the most extensivley studied of the Opisthorchiidae. At least 680 million people worldwide are at risk of infection of these liver flukes through the consumption of raw or partially cooked freshwater cyprinid fish. An estimated 45 million people in Europe and Asia are currently infected with these liver flukes. Of these, the 35 million are infected with C. sinensis mainly in China, 10 million with O. viverrini in Southeast Asia, and 1.2 million with O. felineus in Eastern Europe and Russia. These liver flukes have been proven to be causative agents of bile duct cancer or cholangiocarcinoma (CCA). A multidisciplinary program should be implemented involving comprehensive research on molecular genetics, diagnosis, treatment, prevention, as well as educational and control programs should progressively be introduced and applied in endemic regions of O. viverrini, O. felineus and C. sinensis throughout their ranges, hence, opisthorchiasis and clonorchiasis free communities can be realised globally.

Opisthorchis felineus infection, risks, and morbidity in rural Western Siberia, Russian Federation

BACKGROUND

The liver fluke, Opisthorchis felineus, is widely distributed throughout Europe and large parts of the Russian Federation. In Western Siberia, information about opisthorchiasis is lacking although infection may lead to severe liver and bile duct diseases. We aimed to assess the current prevalence of O. felineus infection along with associated risk factors and morbidity in rural Western Siberia.

METHODS

We conducted a community-based, cross-sectional study in the rural Shegarskiy district, Tomsk Oblast, Russian Federation. All household members (≥ 7 years) present on the survey day were enrolled (n = 600). Two stool samples per person were examined for helminth eggs, using PARASEP (DiaSys Ltd, UK). The number of eggs per gram (EPG) of feces was recorded. Each study participant was interviewed to determine risk factors, using a pre-tested questionnaire. An abdominal ultrasonography examination of liver and bile ducts was performed with a mobile, high resolution ultrasound device. In total, 488 persons completed assessments (two stool samples, completed questionnaires); of those, 436 individuals had an ultrasonography (US) examination.

RESULTS

We observed a prevalence of O. felineus infection of 60.2%. Significant risk factors for infection were the consumption of river fish (odds ratio from adjusted analysis [aOR] 2.4, 95% CI 1.52-3.95, p<0.001), particularly stock fish (OR from multivariable analysis [mOR] 3.2, 95% CI 2.63-3.80, p<0.001), smoked fish (mOR 1.5, 95% CI 1.24-1.72, p<0.001), frozen fish (mOR 1.6, 95% CI 1.29-2.02, p<0.001), and raw fish (mOR 1.4, 95% CI 1.05-1.84, p = 0.02); and fishing activities (mOR 1.2, 95% CI 1.03-1.43, p = 0.019). Women had a higher risk of infection than men. Infection was associated positively with age and negatively with socio-economic status. The respondents' general awareness of opisthorchiasis was quite high (93.2%), but their knowledge about infection transmission and prevention was insufficient. Children aged 7-18 years old had a lower level of awareness compared to adults. The abdominal ultrasonography results demonstrated a strong association between O. felineus infection and gallbladder stones (mOR 2.8, 95% CI 1.33-6.04, p = 0.007) and periductal fibrosis of intrahepatic bile ducts (mOR 1.9, 95% CI 1.08-3.46, p = 0.026).

CONCLUSION

O. felineus infection is highly prevalent in rural regions of Western Siberia, and associated with severe hepatobiliary pathology. Identified risk factors will be used to develop a comprehensive targeted O. felineus infection control program.

The Curious Case of Cholangiocarcinoma: Opportunities for Environmental Health Scientists to Learn about a Complex Disease

Deaths from complex, noncommunicable diseases such as cancer are predicted to continue to increase worldwide, with low- and middle-income countries bearing the brunt of the burden. This problem requires a concentrated global effort to avoid devastating losses of life as well as economic losses. Cholangiocarcinoma (CCA) is a readily studied model of complex, noncommunicable disease, but it receives little attention outside of the scientific community in Southeast Asia. Here, we bring attention to the opportunity to study CCA as a model to understand the role of multiple, complex factors in cancer. These factors include allostatic load, individual genetic susceptibility, and environmental exposures such as chemicals, diet, socioeconomic factors, and psychosocial stress. The study of CCA offers a unique opportunity to make novel observations that could advance progress in prevention and intervention approaches for prevalent diseases that involve complex, multifactorial interactions.