Rate of incidence therefore is greatly increased in poor communities and populations because of the lack of adequate housing. This occurs in significantly higher proportions during the peak of the dry season in local communities. Reservoirs and transmission
T. penetrans has been documented to use various warm-blooded animals as reservoir hosts, including humans, pigs, dogs, cats, rats, sheep, cattle, donkeys, monkeys, birds, and elephants. These hosts directly propagate the disease by being the origin of the next generation of fleas. Once the female flea expels 100–200 eggs, the cycle of transmission begins again. Lifecycle
T. penetrans eggs, on average, are 604 μm long, The larva will hatch from the egg within one to six days, assuming the environmental conditions (e.g., moisture, humidity, etc.) are favorable. After hatching, the flea will progress through two instar phases. This is unique in that most fleas go through three, instead. Over the course of that development, the flea will first decrease in size from its just-hatched size of 1,500 μm to 1,150 μm (first instar) before growing to 2,900 μm (second instar).About 6 to 8 days after hatching, the larva pupates and builds a cocoon around itself. Because it lives mostly on and below the surface of the sand, sand is used to stabilize the cocoon and help to promote its development. An environmental disturbance such as rain or a lack of sand have been shown to decrease incidence, most likely due to decreasing the environmental factors (i.e., sand) on which the flea depends for overall growth.
In 2004, 3M obtained FDA approval to market imiquimod as a treatment for superficial basal cell carcinoma.In 2006, 3M sold its pharmaceutical business in the Americas to Graceway Pharmaceuticals, its European pharmaceutical business to Meda AB, and its pharmaceutical business in other territories to two private equity firms.Graceway declared bankruptcy in 2011, after the expiration of the patents on imiquimod, and its assets, including the rights to imiquimod branding and approvals in the Americas, were purchased by Medicis Pharmaceutical.Imiquimod 5% was approved for medical use in the European Union in September 1998. Imiquimod 3.75% was approved for medical use in the European Union in August 2012.As of 2015, imiquimod is generic and is available worldwide under many brands. Research
One randomized double-blind Phase III clinical study found clearance of genital warts (an FDA-approved indication) improved from 9% with placebo to 24.9% with 3.75% imiquimod cream applied for up to eight weeks.Imiquimod has been tested for treatment of molluscum contagiosum. Two large randomized controlled trials, however, found no evidence of effectiveness of imiquimod in treating children with molluscum contagiosum, and concerning adverse effects were also noted. These disprove earlier anecdotal claims and smaller, less reliable studies.Imiquimod has also been tested for treatment of vulvar intraepithelial neoplasia, vaginal intraepithelial neoplasia, common warts (a 2012 Cochrane review found no randomized controlled trials), plantar warts, warts in people with suppressed immune systems, flat warts on face and neck, and warts under and around fingernails and toenails.