Thus the myiasis is described as either:obligatory, where the parasite cannot complete its life cycle without its parasitic phase, which may be specific, semispecific, or opportunistic
facultative, incidental, or accidental, where it is not essential to the life cycle of the parasite; perhaps a normally free-living larva accidentally gained entrance to the hostAccidental myiasis commonly is enteric, resulting from swallowing eggs or larvae with ones food. The effect is called pseudomyiasis. One traditional cause of pseudomyiasis was the eating of maggots of cheese flies in cheeses such as Stilton. Depending on the species present in the gut, pseudomyiasis may cause significant medical symptoms, but it is likely that most cases pass unnoticed. Prevention
The first control method is preventive and aims to eradicate the adult flies before they can cause any damage and is called vector control. The second control method is the  treatment once the infestation is present, and concerns the infected animals (including humans).The principal control method of adult populations of myiasis inducing flies involves insecticide applications in the environment where the target livestock is kept. Organophosphorus or organochlorine compounds may be used, usually in a spraying formulation. One alternative prevention method is the sterile insect technique (SIT) where a significant number of artificially reared sterilized (usually through irradiation) male flies  are introduced.
Avanafil is a PDE5 inhibitor approved for erectile dysfunction by the FDA on April 27, 2012 and by EMA on June 21, 2013. Avanafil is sold under the brand names Stendra and Spedra. It was invented at Mitsubishi Tanabe Pharma, formerly known as Tanabe Seiyaku Co., and licensed to Vivus Inc., which partnered with Menarini Group to commercialise Spedra in over forty European countries, Australia, and New Zealand. Metuchen Pharmaceuticals obtained exclusive rights within the United States.Avanafil acts by inhibiting a specific phosphodiesterase type 5 enzyme found in various body tissues, primarily in the corpus cavernosum penis. Other similar drugs are sildenafil, tadalafil and vardenafil. The advantage of avanafil is that it has very fast onset of action compared with other PDE5 inhibitors. It is absorbed quickly, reaching a maximum serum concentration in about thirty to forty-five minutes. About two-thirds of the participants were able to engage in sexual activity within fifteen minutes. Medical use
Avanafil is used to treat erectile dysfunction (ED). Adverse effects
Although avanafil is generally well tolerated, dose dependent adverse effects can occur. The most common adverse effects include headache, flushing, nasopharynigitis, nasal congestion, and back pain. While it is also uncommon, there is a potential for visual disturbances to occur in patients. Mechanism of action
Avanafil inhibits phosphodiesterase-5, preventing the degradation of cGMP. The increased levels of cGMP causes vasodilation, resulting in an increased blood flow in the penis. Avanafils mechanism of action takes places once nitric oxide is released, in association with sexual stimulation.