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Biomedical subjects

Maria Vang Johansen

Publications and source records attributed to Maria Vang Johansen.

9 recordsLinked to original sources

Cross-sectional parasitological survey for helminth infections among fish farmers in Nghe An province, Vietnam.

A total of 964 adult fish farmers in five eastern districts in Nghe An province, Vietnam were investigated in late 2004 for food-borne trematodes and other helminth infections using duplicate Kato-Katz thick smears prepared from single stool samples. Eggs of fish-borne trematodes and of Fasciolopsis buski were found in 0.6 and 0.7% of farmers, respectively. Infection prevalences with soil-transmitted helminths (STHs), namely Ascaris lumbricoides, Trichuris trichiura and hookworm, were 34.8, 50.7 and 51.3%, respectively, and 81.8% were infected with at least one of the three STHs. While A. lumbricoides and T. trichiura were more prevalent in the eastern districts compared to the more western districts, the opposite was true for hookworm infections. The widespread prevalence of STH infections in fish farmers suggests that control of these infections in school-age children only may be inadequate. Identification of the human behavioural factors and environmental features responsible for the distribution and frequency of STHs among adults is needed as well as a sensitive diagnostic test of fish-borne trematodes at species level.

Adult↗

Transmission of Schistosoma japonicum by humans and domestic animals in the Yangtze River valley, Anhui province, China.

The aim of the present work was to assess the relative contribution to transmission of Schistosoma japonicum by humans and domestic animals in two villages in the Yangtze River valley in Anhui province, China. A cross-sectional survey was conducted to determine the prevalence and intensity of S. japonicum in humans, cattle, water buffaloes, horses, pigs, goats, dogs and cats. Additionally, for each host species the number of individuals and the mean faecal excretion per day was determined. Results showed that both prevalence and intensity of infection varied significantly between species and between the two villages and neither of the variables gave an adequate picture of the potential transmission. Total daily egg excretion was significantly higher in Chenqiao village compared with Guanghui village. Whereas humans were the main contributors to transmission of schistosomiasis in Guanghui village (80.4%), water buffaloes accounted for nearly 90% and goats for more than 5% of the transmission in Chenqiao village. Hence, the present study suggests that schistosomiasis transmission might vary significantly within Chinese farm districts and successful control should rely on prior transmission index determinations on major potential contributors rather than routine data of prevalence and intensity of infection. Further studies should determine the value of adding other transmission variables like egg hatchability and faecal deposition habits.

Adult↗

Gender-associated gene expression in two related strains of Schistosoma japonicum.

Host inflammatory responses directed against eggs laid by sexually-mature Schistosoma japonicum female worms instigate lesion formation and associated clinical pathologies during infection. To identify parasite gene transcripts that associate with egg production and to characterise sexually-mature adult gene expression profiles of two related Chinese strains, S. japonicum cDNA microarrays were fabricated using 457 ESTs originating from three parasite developmental stages. Twenty-two female-associated and 8 male-associated gene transcripts were identified in the adult Anhui strain whereas 21 female-associated and 7 male-associated gene transcripts were revealed in the adult Zhejiang strain. RT-PCR analysis, in situ enzyme localisation studies and enzymatic assays confirmed the cDNA microarray results, and importantly, provided information previously unappreciated in schistosome conjugal biology. Specifically, our novel findings include the female-specific expression of genes putatively involved in haemoglobin digestion and eggshell formation including extracellular superoxide dismutase, two histidine-rich proteins, a large blood-brain barrier amino acid transporter and two tyrosinase orthologues. In contrast, transcripts involved in mechanical support (actin), cytoskeletal infrastructure (e.g. dynein light chain 3 and myosin regulatory light chain) and tegumental biology (e.g. TM4SF and Sj25) were more highly represented in adult male schistosomes. Together these data establish a transcriptional basis for adult schistosome labour division and expands the list of novel S. japonicum gender-associated gene transcripts that may be considered targets for improved intervention strategies.

Animals↗

Research ethical challenges in cross-disciplinary and cross-cultural health research: the diversity of codes.

The scope of health research has increased considerably during the last three to four decades, both geographically and regarding the range of disciplines participating in biomedical research. In other words cross-cultural and cross-disciplinary projects are much more common in the World's biomedical research of today. For the large part that involves human research subjects, ethics based on fundamental human values is still an integrated part of project planning and management. However, in the light of the increasing complexity of research, the controlling codes (i.e. laws, declarations, conventions and guidelines) have undergone important changes and have increased considerably in numbers. Hence, groups from different disciplines and cultures need to adjust their projects' research ethical policies and implementations in accordance with the various codes' common denominators. Sometimes research ethical codes are even incompatible at certain points. The article describes key ethical aspects of cross-cultural and cross-disciplinary projects, with special emphasis on acquiring consent, avoiding harm, attending to needs, and describing the obligations when a project is over. On this background the authors conclude that researchers in the planning phase of a project should: 1) seek knowledge and professional advice related to the transgression of cultural and disciplinary borders, 2) introduce a long-term perspective for a project's activities and consequences, and 3) select the appropriate among the existing many ethical codes. These suggestions apply to several stakeholders: researchers, scientific societies, agencies for scientific support, information and ethical control, as well as research political agencies.

Biomedical Research↗

Validation of ultrasonography for hepatic schistosomiasis using a porcine Schistosoma japonicum model.

Ultrasonography is increasingly used to record hepatosplenic involvement in schistosomiasis. However, questions remain unsolved regarding diagnostic accuracy in mild hepatic disease and under influence of confounders like co-infections. We report on a study to evaluate the suitability of a pig model of schistosomiasis japonica to investigate such problems. Nine pigs (12 weeks of age) were infected with 1000 Schistosoma japonicum cercariae. Together with 10 uninfected controls, they underwent B-mode and Doppler ultrasonography 12 weeks after infection, followed by parasitological and gross pathological examination and quantification of hepatic collagen. At this time, all infected pigs had patent infection, hepatic displacement of ova and various grades of portal and septal liver fibrosis. Sonographically, echogenic portal thickening (ePT), increased hepatic echogenicity (EG), increased hepatic dimensions and dilatation of the portal vein were found to correlate with other parameters of morbidity. Algorithms from human medicine were appropriate to grade ePT in the pig model. It is concluded that the porcine model of schistosomiasis japonica can be instrumental in approaching problems which for any reasons cannot be studied in human beings.

Animals↗

Improving meat inspection and control in resource-poor communities: the Nepal example.

Meat is an important source of protein and a valuable commodity in resource-poor communities. In many developing countries, lack of appropriate slaughtering facilities and unsatisfactory slaughtering techniques are causing unnecessary losses of meat as well as invaluable by-products from animal carcasses. Slaughtering places are frequently contaminated and may not be protected against dogs, rodents and insects. Meat products coming from such conditions are often deteriorated due to bacterial infection or contaminated, which may cause food poisoning or diseases in consumers. In many developing countries, regulations concerning meat inspection and/or control are inadequate or non-existent allowing consumers to be exposed to pathogens including zoonotic parasites. In Nepal, buffaloes contribute about 64% of the meat consumed, followed by goat meat (20%), pork (7%), poultry (6%) and mutton (2%). Goat and poultry meat is acceptable to all castes of people while buffalo meat is consumed mainly by the Newar ethnic group. Previously, pork was consumed only by people belonging to low castes, however, in recent years, the consumption of pork has increased in higher castes as the caste system has become more relaxed. Until recently, there were no official meat inspection regulations in the country, however, in 1999, the national government legislated an as-yet-to-be implemented Animal Slaughtering and Meat Inspection Act which mandates slaughterhouse construction and meat inspection and control. Due to the lack of implementation of the Meat Inspection Act and resultant absence of meat inspection, meat from sick or parasite-infected animals is serving as a source of infection to humans as well as other animals. In addition, meat quality is adversely affected by careless handling conditions in the slaughtering places as well as in the meat markets or shops. For improvement in animal slaughtering and meat inspection in both rural and urban areas of Nepal, several strategies are to be recommended. Sustainable capacity building should be introduced including training of veterinarians, meat inspectors and butchers as well as building of slaughter facilities. Government policies on slaughter procedures including ante-mortem examination, meat inspection and stamping of meat should be implemented. Programmes should be instituted with strong focus on prevention and control of meat-borne diseases to reduce infection risk of consumers and meat handlers and to avoid contamination of the environment. Lastly, emphasis should be put on improving the animal husbandry system in Nepal. These same actions can be undertaken in other developing countries to assist with improving meat inspection and control, thus helping with prevention and control of cysticercosis as well as other important meat-borne diseases.

Animals↗