[5] Recently, it has been hypothesized through two studies[6] that certain members of the Leishmania genus (e.g. L. braziliensis) are capable of sexual reproduction in the gut of the sandfly vector.

[8] These environmental changes put more people at risk with the vector and cause a greater geographic distribution of the sandfly and, consequently, the infectious disease.

The Grande Seca of 1877 to 1878 led to the mass migration of approximately 55 thousand Brazilians from Ceará to the Amazon for employment on rubber plantations.

[11] Direct and primary evidence of leishmaniasis' existence is extremely minimal as the disease was not known to the Northeast and therefore was not identified and labeled until 1895 in Bahia.

In 1827, before the Great Drought, Rabello cites reports from missionaries in the Amazon region seeing people with skin lesions that fit the description of the disease.

In 1909, the newly graduated medical student at the time of the drought, Studart, reported a skin condition that has the potential of being leishmaniasis.

After contracting and spreading the disease within the plantations, workers later left the Amazon and returned to the Northeast carrying the parasite and introducing the first cases of leishmaniasis to the state.

The environmental conditions and the socio-economic factors of the drought-stricken Ceará made the area perfect and the people vulnerable to the spread of leishmaniasis.

The drivers of the disease target those that live in crowded and underdeveloped housing near rubbish, sewage, and polluted water sources.

Leishmaniasis is found more commonly in favelas or "shanty towns" as the residents have increased risks and live in "overcrowded conditions with inadequate housing and sanitary facilities" (Arias, J R et al.).