Risk factors for infection by the Entamoeba histolytica/E. dispar complex: An epidemiological study conducted in outpatient clinics in the city of Manaus, Amazon Region, Brazil

Abstract

An epidemiological study was conducted on a population attending outpatient clinics in Manaus, Amazon, Brazil to determine the prevalences of infection by the Entamoeba histolytica/E. dispar complex and by E. histolytica alone, as well as to identify the risk factors involved in transmission. The study was conducted in two phases: survey and case-control. Face-to-face interviews were carried out and faecal samples collected from 1578 individuals. Faeces were examined by optical microscopy and tested for the pathogenic E. histolytica specific antigen. Positivity to E. histolytica/E. dispar was 21.5% (340 cases). Cases were compared with 340 control samples, negative for the E. histolytica/E. dispar complex based on examination by optical microscopy. The analysis was conducted by logistic regression. The risk factors identified were: place of residence, age, ingestion of raw vegetables, quality of water consumed, number of rooms and bedrooms per house, and having other protozoan infections. Specific antigen detection tests identified 22 participants infected by E. histolytica (6.8%) among those positive for E. histolytica/E. dispar. There was a higher proportion of males among participants infected by E. histolytica than among those with E. dispar infections. The study population was asymptomatic or presented non-specific symptoms that could be attributed to amoebiasis.

Prevalence and risk factors for intestinal protozoa infection in elderly residents at Long Term Residency Institutions in Southeastern Brazil

“…This protozoan is common in inhabitants of developing countries, affecting predominantly people living with precarious socioeconomic conditions, inadequate hygiene practices and malnutrition 24 . The prevalence of this parasite is influenced by local agglomeration, inadequate supply of water, quality of consumed water, lack of basic sanitation, bathroom habits, lack of adequate urban services, age, ingestion of raw vegetables, number of bedrooms and bathrooms per house and the presence of other intestinal protozoa 4 .…”

High occurrence of Entamoeba histolytica in the municipalities of Ariquemes and Monte Negro, State of Rondônia, Western Amazonia, Brazil

“…dispar obtained by optical microscopy in Manaus (state of Amazonas) and Belém (state of Pará), both in the northern region of Brazil, were 21.5% and 24.8% respectively 1,13 . These findings are lower than those obtained in Ariquemes 61% (50/82) and Monte Negro 44% (59/134).…”

Entamoeba histolytica

“…Individuals in houses with less than five rooms had amebiasis with greater infection risk compared to those living in houses with more rooms (Benetton et al, 2005). Prevalence of E. histolytica infection could also be higher among members of family eating with their fingers or at the same plate (Oyerinde et al, 1979).…”

“…Food can become contaminated at several stages: during production, harvesting, handling, transport, and preparation processes. The risk of foodborne transmission is increased when food is consumed raw or undercooked (Benetton et al, 2005). Food handlers are another possible source of infection, as are mechanical vectors such as flies and cockroaches (Schuster and Visvesvara, 2004).…”

“…In Brazil, Benetton et al (2005) estimated that the risk of acquiring amebiasis was 1.6 times greater among persons who ate raw vegetables than among those who do not eat raw vegetables. They also highlighted the causes of contamination and related it to the quality of the water used to wash vegetables and to habits of food preparation.…”