Microrganismos e parasitos em água destinada ao consumo humano proveniente da Zona Rural de Santo Antônio de Jesus – Bahia

Abstract

The access to potable water is a basic human right. However, water may be contaminated at its source, during distribution, as well as in household tanks. Foodborne illness represent a relevant public health issue and have several etiological agents, such as bacteria, virus, helminthes, protozoa and fungus. Those microorganisms have a cosmopolitan distribution and similar transmission mechanisms. Its occurrence has been increasing significantly worldwide, especially in places where the population’s socioeconomic conditions are more precarious, such as rural areas. Furthermore, water treatment in rural communities is a challenge. Alternative treatments are not always efficient or performed correctly. Hence, the goal of this study was to evaluate the bacteriological, parasitological, physical and chemical quality of water destined for human consumption in a rural community at Recôncavo da Bahia, ascertaining the factors that could be related to a possible contamination; also studying the in vitro antimicrobial effects of exposure to light (450 nm) in raw water intended for human consumption, investigating the relationship of the results with the physical and chemical parameters. In order to evaluate the water quality, the study was carried out in 53 households, by the end of both rainy (August to September 2015) and dry seasons (April 2016). The presence of total coliforms, Escherichia coli were evaluated; a parasitological evaluation was performed; heterotrophic bacteria were quantified; pH, temperature, dissolved oxygen, apparent color, turbidity and salinity were analyzed; a questionnaire concerning the source of water and its storage was applied. All samples were in disagreement with the parameters allowed and recommended by the Brazilian legislation. According to the data obtained, the water source, the presence of a reservoir at the households, the sewage destination and the cleaning time of the reservoir were directly related to the bacteriological results. For the rating of the antimicrobial effect in vitro, 15 samples were collected from the same rural area community. The samples were directly exposed to a light system consisting of a light emitting diode for 10 hours. The quantifications of heterotrophic bacteria, total coliform and temperature were realized every two hours. The bacterial analysis was repeated after 72 hours exposure finalization. The pH, dissolved oxygen and salinity analysis were made before each experiment. There has been a significant reduction in both bacteriological parameters analyzed after treatment. The average reduction of heterotrophic bacteria was 97,01 % and total coliform, 95,61 %. The parameters pH, dissolved oxygen and temperature had direct relationship with the percentage reduction of heterotrophic bacteria. Thus, the consumption of the analyzed samples may represent a risk to the population’s health, and could even lead to outbreaks of foodborne illness. Effective water treatment measures should be taken in order to minimize the risk to human health. Because of its uniqueness, this study may serve as an initial effort to find new methods of water disinfection. With additional research, the process can be improved, making viable a new water disinfection method to be applied in loco. CA´PÍTULO 1 = Foodborne illness is a syndrome caused by the ingestion of food and/or water containing contaminant agents in amounts that affect the consumer’s health, in an individual level or population groups. In the last 15 years, water was the third major cause related to foodborne illness outbreaks in Brazil, with different etiologic agents involved, such as bacteria, like Escherichia coli, and protozoa, like Giardia spp..These microorganisms have cosmopolitan distribution and similar transmission mechanisms, in addition to being directly related to the absence or precariousness of socioeconomic conditions and basic sanitation. The Brazilian Ministry of Health, through Ordinance MS 2914/2011, establishes drinking water standards for human consumption and provides procedures for the control and monitoring the quality of this water. This legislation defines several parameters allowed and recommended for water destined for human consumption. For the bacterial evaluation, it uses indicator microrganisms such as heterotrophic bacteria, total coliforms and Escherichia coli. Simultaneously, it addresses a series of physical and chemical parameters such as pH, apparent color and turbidity. As well as it recommends parasitological analysis in specific bacterial contamination conditions. For it to become potable, the water can undergo various types of treatments, such as chlorination, boiling, filtration and exposure to sunlight and ultraviolet light. Each system has advantages, disadvantages and limitations. Positive and negative points should to be taken into consideration while choosing the most adequate disinfection system to the consumer’s needs. Effective water treatment measures are taken to minimize the risk to human health. CAPÍTULO 2 = This work aimed to evaluate the bacteriological, parasitological, physical and chemical quality of water intended for human consumption in a community in a rural area of Recôncavo of Bahia (Brazil), and the factors related to a possible contamination. Samples were collected at two different times: at rainy season (August to September 2015) and dry season (April 2016). The present work evaluated the presence of total coliforms, Escherichia coli; it quantified heterotrophic bacteria; it performed parasitological techniques for direct examination and modified Faust; it analyzed pH, temperature, dissolved oxygen, apparent color, turbidity and salinity; it applied a questionnaire regarding the water source and its storage. Out of the 53 households, 67.9 % were in disagreement with bacteriological standards of potability. 5.7 % in disagreement with parasitological standards, 92.5 % in disagreement with physical and chemical standards and all samples were in disagreement with the parameters allowed and recommended by the Brazilian legislation. The water source (p = 0.002), presence of a household reservoir (p = 0.004), sewage destination (p = 0.004) and reservoir cleaning time (p = 0.003) were directly related to the bacteriological results. The consumption of this water poses a risk to the population’s health, and it could provoke outbreaks of foodborne illness. Effective water treatment and remedial me asurements should be taken in order to minimize risks to human health.