Abstract
1. Opisthorchis viverrini is a water-based disease-causing parasite
whose public health implications are relevant in particular in Southeast
Asia despite broad control efforts and education campaigns. Untreated or
chronic infections often lead to severe hepatobiliary morbidity
including cholangiocarcinoma, an often lethal bile duct cancer. The
liver fluke O. viverrini is the causative agent of opisthorchiasis, and
can be contracted by consumption of raw fish, after which it settles in
the small intrahepatic bile ducts. The life cycle involves, besides
freshwater snails in which asexual reproduction takes place, freshwater
cyprinid fishes (family Cyprinidae) as intermediate hosts. Piscivorous
mammals, including humans, dogs and cats, act as definitive hosts. 2.
Here, we propose a spatially explicit model for the transmission
dynamics in realistic freshwater environments. Our model generalizes
existing mathematical models, in particular by assimilating novel types
of spreading mechanisms in space and time. We explore theoretically the
range of outcomes that the proposed framework produces, and its basic
sensitivity and stability analyses; 3. Our study emphasizes that
hydrological connectivity is key to shaping patterns of disease spread.
Fish distribution and mobility also affect disease inroads. Our study
provides baseline information on the role of connected freshwater bodies
and their suitability for intermediate and final hosts. The
distributions of fish catch and fish market supplies are also considered
because they affect the spatiotemporal spread of opisthorchiasis; 4.
Adding a spatial resolution to transmission models changes fundamentally
the epidemiological descriptions and the related scenarios of disease
propagation and allows an improved description of the ecology of hosts,
parasites, and their infection cycles. 5. The improvement that the work
provides is a much more realistic description of the environment where
infection cycles develop and spread, reflected in the inclusion of
relevant, hitherto neglected, epidemiological factors.