Diet and disease: transgressing boundaries between science and society-understanding neglected diseases through the lens of cultural studies and anthropology

Diagnosis of helminths depends on worm fecundity and the distribution of parasites within hosts

Helminth transmission and morbidity are dependent on the number of mature parasites within a host; however, observing adult worms is impossible for many natural infections. An outstanding challenge is therefore relating routine diagnostics, such as faecal egg counts, to the underlying worm burden. This relationship is complicated by density-dependent fecundity (egg output per worm reduces due to crowding at high burdens) and the skewed distribution of parasites (majority of helminths aggregated in a small fraction of hosts). We address these questions for the carcinogenic liver fluke Opisthorchis viverrini, which infects approximately 10 million people across Southeast Asia, by analysing five epidemiological surveys (n = 641) where adult flukes were recovered. Using a mechanistic model, we show that parasite fecundity varies between populations, with surveys from Thailand and Laos demonstrating distinct patterns of egg output and density-dependence. As the probability of observing faecal eggs increases with the number of mature parasites within a host, we quantify diagnostic sensitivity as a function of the worm burden and find that greater than 50% of cases are misdiagnosed as false negative in communities close to elimination. Finally, we demonstrate that the relationship between observed prevalence from routine diagnostics and true prevalence is nonlinear and strongly influenced by parasite aggregation.

Masculinity and misinformation: Social dynamics of liver fluke infection risk in Thailand

Liver fluke infection through the consumption of raw or undercooked freshwater fish is a major public health problem in the Mekong Region. Despite the extensive efforts of liver fluke health campaigns, Northeast Thailand still reports high human infection prevalence as consumption of raw fish dishes has diminished but not ceased. This study examines the roles of social-cultural factors, particularly the influences of masculinity and misinformation, on liver fluke infection risk. Participant observation, questionnaire surveys and semi-structured interviews were conducted in four villages in Kalasin Province, Thailand, to scrutinize reasons for raw fish consumption, gender differences in raw fish culture, processes of liver fluke information dissemination, and the extent of information mismatch. Our results show that one of the key reasons (76.9%) underlying continued raw fish consumption are deeply embedded cultural practices associated with ways of rural life. About 30% of the participants indicated that they would not avoid eating raw fish, regardless of knowing the health consequences. Gender difference is evident, with 75.6% of males consuming raw fish salad (koi pla), compared to 42.7% of females. Some male participants associate raw meat consumption with virility and strength. Such beliefs underscore the cultural linkage of koi pla consumption with masculinity. Misconceptions of liver fluke life cycle and risk of infection remain, as only 15.3% of the participants correctly selected raw fish as the food source for liver fluke infection while 84.2% misunderstood that other raw foods could lead to infection. The multi-layered and hierarchical structure of public health information dissemination from medical professionals to health officers and village health volunteers to villagers has contributed to information mismatch between different layers. Our study builds on others which call for multi-pronged scientific and social strategies, as well as culturally attuned approaches to public health messaging. The study raises masculinity and misinformation as relevant considerations in disease prevention. Incorporating grounded research and gendered perspectives are part of appreciating the cultural roots of raw fish consumption. Realizing the significant role of village health volunteers in information dissemination and in supplying coherent public health messages is vital for effective health campaigns.

Cholangiocarcinoma: a guide for the nonspecialist

Cholangiocarcinoma (CCA) is a tumor with increasing prevalence around the world. The prevalence of CCA is highest in East Asia and most significantly in the countries through which the Mekong River flows, owing to the presence of liver flukes, which are consumed in raw fish dishes. Outside Asia, the causes of bile duct cancers for the most part are unknown. In this review, we assess the current state of knowledge in both fluke-associated and sporadic CCA, from etiological, diagnostic, and treatment perspectives.

Sociocultural dynamics that influence Chagas disease health care in Colombia

Chagas disease (CD) is a Latin America endemic and neglected tropical disease that affects primarily poor people living in rural areas. Its current low profile leads to many diagnostic, treatment, and control challenges. This study aimed to identify and characterize the sociocultural dynamics that influence CD health care in Colombia. Data for our ethnographic study was collected in 2013 and included participant observation in two main endemic areas in Colombia. In addition, 81 people belonging to four groups (patients and family members; health care workers; researchers; and officers) were recruited through snowball sampling technique and participated in informal and semi-structured interviews. People from the first two groups also participated in social cartography excercises. Data analysis resulted in the identification of three main sociocultural dynamics. Local Understandings: Patients reported confusions around disease transmission, treatment effectiveness and development of future complications. Providers' Knowledge and Training: Failures in professional's knowledge and training mostly affect the primary level of care in rural areas. Professionals undergo minimal training during medical school and lack access to continuous education. In contrast, clinicians working at tertiary university hospitals or at the CD unit of the Colombian National Institute of Health (NIH) exhibited great knowledge and competency. Health Care System Barriers: The Colombian market-based health care reform augmented access barriers, which impacted CD care greatly. We identified geographic and bureaucratic itineraries that depended on type of insurance plan, insurance contracts with service providing institutions, and levels of care. This study shows that people's experience of these sociocultural dynamics vary depending on their mobility from rural to urban contexts. It unveils the importance of analyzing the structure of the health care system. In the Colombian case, its for-profit orientation has become one of the most important obstacles for comprehensive, integrated, and timely health care responses.