Urban malaria in the Brazilian Western Amazon Region I: high prevalence of asymptomatic carriers in an urban riverside district is associated with a high level of clinical malaria

Abstract

Cross sectional studies on malaria prevalence was performed in 2001

Basic sanitation, socioeconomic conditions, and degree of risk for the presence and maintenance of malaria in a low-transmission area in the Brazilian Amazon

“…The predominance of cases of adults and males performing activities considered high risk for contracting the disease corroborates other studies in the Amazon region (16) (20) (22) . However, the urbanization of malaria occurs due to an increase in migratory fl ow, because individuals infected while working bring the pathogen to urban areas, where the high population density and the rural habits of populations with lower QLI, living in environmentally fragile environments, favor the spread of malaria (24) .…”

“…Poor socioeconomic and sanitation conditions are factors directly related to maintaining the high prevalence and incidence of parasitic diseases such as malaria (16) . In addition, there are numerous health problems resulting from poor education of the population that require corrective and/or educational measures.…”

“…In fact, adult males are more susceptible due to their greater displacement in the Amazon region and their involvement in activities in environments conducive to transmission (16) (20) . Although a minority (22.2%) of individuals reported activities in the last 15 days relating to agriculture, gold mining, plant extractivism, road/dam construction, mining, and traveling, notably, the option other activities was marked on 54% (68/126) of the forms analyzed, and such information was missing from 23.8% (30/126) of the forms.…”

“…However, we must consider that the occurrence of a malaria outbreak in this case could also be a consequence of the autochthonous transmission of P. vivax or relapses (old malaria profi le) (19) (25) and may not necessarily be related to recent introduction of the disease to this area. Furthermore, asymptomatic carriers of P. vivax could have some epidemiological importance as a source of infection for vectors (16) (19) , since they are able to maintain the parasite transmission.…”

Risk analysis of the re-emergence of Plasmodium vivax malaria in Japan using a stochastic transmission model

“…Consequently, a delay in the diagnosis increases the possibility of expanding infections in the vicinity of the infected person [32,33]. However, the model in the present study was limited to patients with symptoms, especially regarding the situation of immigrants.…”