<P> Currently, F. hepatica has one of the widest geographical spread of any parasitic and vector - borne disease . Originating in Europe, it has expanded to colonize over 50 countries, covering all continents except Antarctica . In contrast, F. gigantica is generally considered more geographically restricted to the tropical regions of Africa, Asia, and the Middle East, with some overlap between the two species . </P> <P> Climate affects both F. hepatica and its definitive host, the snail . For example, the development of F. hepatica miracidia and larvae, and the reproduction of Galba truncatula, require a temperature range of 10 to 25 ° C. In addition, they both require high levels of moisture in the air, as both are at risk of desiccation . Due to this, the prevalence, along with the intensity of infection, of F. hepatica is primarily dependent on rainfall levels and temperature . </P> <P> F. hepatica's tegument protects it from the enzymes of the host's stomach, whilst still allowing water to pass through . Free - swimming larvae have cilia and the cercariae have a flagellum - like tail to help them swim through the aquatic environment and also allow them to reach the plants on which they form a cyst . To attach within the host, F. hepatica has oral suckers and body spines . Their pharynges also help them to suck onto the tissues within the body, particularly within the bile ducts . The adult fluke's respiration is anaerobic; this is ideal, as no oxygen is available in the liver . F. hepatica is adapted to produce a large number of eggs, which increases its chances of survival, as many eggs are destroyed on release into the environment . Also, F. hepatica is hermaphrodite, thus all flukes can produce eggs, increasing the number of offspring produced by the population . </P> <P> The genome for F. hepatica was published in 2015 . At 1.3 Gb, its genome is one of the largest known pathogen genomes . The genome contains many polymorphisms, and this represents the potential for the fluke to evolve and rapidly adapt to changes in the environment, such as host availability and drug or vaccine interventions . </P>

Adaptations of fasciola hepatica to a parasitic lifestyle
find me the text answering this question