Microbiological quality of drinking rainwater in the inland region of Pajeú, Pernambuco, Northeast Brazil

Qualidade microbiológica da água potável no interior, região de Pajeú, Pernambuco, nordeste do Brasil

MICROBIOLOGY

Microbiological quality of drinking rainwater in the inland region of Pajeú, Pernambuco, Northeast Brazil

Qualidade microbiológica da água potável no interior, região de Pajeú, Pernambuco, nordeste do Brasil

Rogério Pereira Xavier^I; Leonardo Pereira Siqueira^I; Fernando Antonio Chaves Vital^I; Francisca Janaina Soares Rocha^II; João Inácio Irmão^II; Glícia Maria Torres Calazans^I

^IDepartamento de Antibióticos, Universidade Federal de Pernambuco, Recife, Pernambuco, Brasil

^IIDepartamento de Medicina Tropical, Universidade Federal de Pernambuco, Recife, Pernambuco, Brasil

^{Correspondence to}

SUMMARY

Despite all efforts to store and reduce its consumption, water is becoming less inexhaustible and its quality is falling faster. Considering that water is essential to animal life, it is necessary to adopt measures to ensure its sanitary conditions in order to be fit for consumption. The aim of this study was to analyze the microbiological quality of drinking rainwater used by rural communities of Tuparetama, a small town located in Northeast Brazil. The study covered seven rural communities, totaling 66 households. In each household two samples were collected, one from a tank and the other from a clay pot located inside the home, resulting in 132 samples (tank plus clay pot). Approximately 90% of samples were below the standard recommended by the current legislation, being considered unfit for human consumption. Part of this high microbiological contamination of drinking rainwater could be related to the lack of sanitary education and of an adequate sewerage sanitation system.

Keywords: Rainwater; Water consumption; Diseases; Parasites; Cisterns.

RESUMO

Apesar de todos os esforços para armazenar e diminuir o seu consumo, a água está se tornando, cada vez menos, inesgotável e sua qualidade vem se reduzindo cada vez mais rápido. Sendo a água imprescindível à vida animal, é necessário que se adotem medidas para garantir sua qualidade higiênico-sanitária a fim de que seja própria para o consumo. O objetivo desse trabalho foi analisar a qualidade microbiológica da água da chuva utilizada pelas comunidades rurais da cidade de Tuparetama, localizada no nordeste do Brasil. O estudo envolveu sete comunidades rurais, totalizando 66 residências. Em cada residência foram coletadas duas amostras, uma da água armazenada na cisterna e outra da água armazenada no pote de barro localizado no interior da residência, resultando em 132 amostras (cisterna mais pote de barro). Aproximadamente, 90% das amostras estavam em desacordo com a Legislação vigente, sendo consideradas impróprias para o consumo humano. Parte dessa elevada contaminação microbiológica da água da chuva armazenada para consumo pode dever-se à falta de educação sanitária e de um sistema de esgotamento sanitário adequado.

INTRODUCTION

The quality of human life seems to be related to the quality of drinking water, because it is a major element able to be used for preparing food, maintaining good personal hygiene and cleaning utensils. Access to safe drinking water is essential for achieving good conditions of health, therefore drinking water cannot have any pathogens and/or toxic chemicals that could damage human organisms. Pathogens such as bacteria, viruses, protozoa and helminths are able to cause human or animal diseases through ingestion or contact with food and contaminated water samples¹.

Water can transmit diseases when a pathogen enters the human body through food, water, hands or soil contaminated with fecal material. Intestinal diseases cause an estimated 1.8 million deaths each year worldwide¹⁸, and these diseases have been discussed in relation to limited access to safe water, inadequate treatment of water for drinking by households, and lack of proper storage practices for drinking water before consumption^6,17,18.

To avoid consumption of contaminated drinking water there are some relatively simple methods, such as chlorination or boiling that can prevent many diseases caused by contamination of food and water sources⁹.

Diarrheal diseases are common in developing countries, mainly in children under three years old that live in poor regions worldwide with low sanitation and bad water quality. This factor contributes to some outbreaks of diarrhea resulting in high rates of child mortality related to the consumption of drinking water^8,12,15.

Water quality seems to be worse in semi-arid regions, especially in poor rural communities, because most of them do not have proper sanitary conditions. In the town of Tuparetama, located in Northeast Brazil, for example, only 4.1% of households have a water supply³, despite the fact that the population consumes rainwater from dams and small reservoirs that are frequently contaminated.

Limited access of households to safe water leads to increased poverty, disease and hunger, problems that could be avoided or solved if the water supply was efficient. More evidence of water problems in semi-arid regions occurs because they have long periods of drought that plague the region and lack of an adequate use of low rainfall. Due to the scarcity of water in semi-arid regions, the idea of storing some rainwater in proper water systems at home in rural areas has been suggested. Rainwater would be useful in times of prolonged drought. The main constraints for domestic rainwater use have been related to its quality which depends on the purity of the atmosphere, and materials used to collect it in households, gutters and pipes².

According to resolution No. 518, March 2004⁴, the Brazilian Ministry of Health recommends investigating the presence of bacteria such as coliforms to define the microbiological standard of water quality⁴. The coliform group includes several bacteria, such as Escherichia, Enterobacter, Citrobacter and Klebsiella, from the Enterobacteriaceae family. As Escherichia coli is a member of normal human flora and can be found in normal human feces, its presence in water reflects a basic test to determine fecal contaminated water or contaminated food¹⁴. It is recommended that other pathogenic organisms such as Giardia spp, Cryptosporidium spp and enterovirus could also be investigated.

Water related disease is a common problem in developing countries, mainly in rural communities that consume rainwater without a proper microbiological quality. This study proposes to evaluate microbiological quality of drinking rainwater in Northeast Brazil and to analyze possible causes of contamination related to water sources, water-handling practices and socioeconomic characteristics of the population.

MATERIAL AND METHODS

Tuparetama is an inland town of the State of Pernambuco, located in the northeast of Brazil, has a population of about 8,177 inhabitants, and a semi-arid tropical climate. The study, undertaken in March and June 2006, involved seven rural communities (with a total of 66 households) of Tuparetama, which was selected due to its historical problems of water supply, poor population and the precarious state of the sanitation infrastructure. Water analysis was sampled in all 66 households and collected from both tank and clay pot inside the residence, totaling 132 samples. The choice for collecting from two points in each household was necessary to determine where the main source of contamination was located, either in tank or earthen pot, and thereby establish a program to raise awareness in communities about the care of water.

A questionnaire was given to each household aimed at collecting data about the existing sanitation, water care, family hygiene habits, including questions about water treatment in tanks and jars, and evaluation of the water quality.

Samples were collected in sterile 200 mL Schott Duran glass bottles. They were washed, dried and then 0.1 mL sodium thiosulfate (Na₂S₂O₃) was added to 10% of each 100 mL of collected water sample. The addition of Na₂S₂O₃ prevents the action of residual chlorine that may exist in the sample, thereby avoiding erroneous results. After Na₂S₂O₃ was added, all bottles were sterilized in an autoclave at 121 ºC for 21 minutes.

Microbiological analysis was performed using chromogenic fluorogenic substrate, a test that is used to identify the presence or absence of total coliforms and Escherichia coli in water samples¹¹. It is based on identification of enzymes produced by coliforms, that can use a defined bacteria substrate able to change color and producing fluorescence under U.V. light irradiation, without confirmatory tests.

Parasite analysis was performed using Hoffman, Pons & Janer method or spontaneous sedimentation. Protozoa cysts are common contaminants of water supplies because they survive a long time in the environment, at least two months in favorable conditions of temperature and humidity¹³. Water samples of 500 mL were collected in non sterile plastic bottles and left for 24 hours while the sedimentation of protozoan cysts and helminth eggs occurred. Lugol was added to 50 mm³ water sediments and a microscope slide analysis was conducted to identify parasitic structures.

Protozoa oocysts were isolated by the Kinyoun method, based on the resistance of the parasite to maintain a red color, acquired through fuchsin, after the addition of an alcohol-acid solution at room temperature. Parasites were observed by immersion objective (100 X).

RESULTS

Bacterial analysis showed that out of the total 132 water samples collected in tanks or pots from the households of the Tuparetama communities, 87.14% presented coliform in tanks and 94.28% in pots (Table 1). Thermotolerant coliform tests were positive in 30% of samples from tanks and 41.42% of clay pots used in the house to store drinking water. The results were therefore at odds with the potability criteria established by Ordinance No. 518/2004⁴ from the Brazilian Ministry of Health.

In order to compare the different focus of bacterial contamination at each residence, from a total of 66 households, 39 did not present any difference of contamination in tank or pot, whereas 20 residences showed a higher contamination in pots, pointing to problems with transport and management of the water supply (Table 2). Only two residences presented suitable drinking water in tank and pot, showing a correct method of water treatment with sodium hypochlorite and cleaning of the pot weekly, according to the questionnaires. Thus, the consensus is that treatment with sodium hypochlorite at least would be effective in order to eliminate bacterial contamination inside houses.

Parasite analysis showed that at least 46 (34.8%) out of a total of 132 households presented one or more parasite (helminth or protozoan) species in rainwater samples from tanks and pots. Cryptosporidium spp oocysts and Giardia spp cysts were positive in approximately 15.9% and 10% of rainwater conserved in pots and tanks, respectively.

Helminth analysis showed the presence of Ascaris lumbricoides and Hymenolepis nana in 16.6% and 1.55% of tanks and pots, respectively. Other parasites such as Entamoeba coli, Entamoeba histolytica/E. dispar, Endolimax nana and Isospora belli were also observed (Fig. 1).

It was also observed from the questionnaires that 35% of the households did not have a sewer system, and none had garbage collection. All garbage was burned in the backyard of the houses. Some people (24%) said that they treated their water tanks with chlorine, but the majority (76%) said that they do nothing to treat the water. Regarding the clay pot, 47% said that they also do nothing to treat this water. Despite this, 81% of the people said that they considered their water as having good quality, and 44% also believe that they could not fall sick because of the water.

DISCUSSION

This study demonstrated the variation of bacterial and parasite contamination of rainwater stored in tanks and pots by people living in some rural communities of Tuparetama. Higher prevalence of bacterial contamination in ready-to-drink water was observed in pots and tank of residences, particularly total coliforms in tanks and Escherichia coli plus total coliforms in pots. High levels of E. coli in water samples means that it was recently contaminated by feces. This fact is according to the answers given at interviews, showing at the same time an absence or inefficient rainwater treatment, and lack of functional disease-prevention proficiency, poor hygiene habits and local sanitary conditions.

High fecal contamination by total coliform in water samples was observed by other authors in groundwater from artesian wells, 97% for total coliform, Pseudomonas and feces coliform and 99.3% for feces coliform^5,7,8.

In this study there was a lower contamination by termotholerant coliform in comparison with other studies, perhaps due to the existence of other microorganisms contaminating the rainwater system, such as bacteria from vegetables and soil contamination⁷.

Although some households declared that they treat their rainwater using chlorine, protozoa contamination continued to be high as observed in pots and tanks, demonstrating that a sodium hypochlorite addition seemed not to be efficient against protozoa contamination, at least in Giardia lamblia positive slides. According to HELLER et al. (2004)¹⁰, Cryptosporidium spp and Giardia spp are resistant to chlorinated water in the amount recommended by Brazilian Health Ministry.

Since sodium hypochloride was not able to destroy protozoa parasite, we investigated the possible effect of this compound to destroy helminth parasite, thereafter an enhanced helminth contamination was sustained in rainwater conserved in tanks and pots of rural communities in Tuparetama. Our results pointed out that Ascaris lumbricoides eggs tested in slides after the addition of sodium hypocloride were also resistant to chlorination (SOARES ROCHA and XAVIER, unpublished data).

Approximately 90% of rainwater samples showed contamination by coliforms and 34.8% showed the presence of at a least one parasite specie such as Cryptosporidium spp, Ascaris lumbricoides and Giardia spp. Such large numbers of contaminants could be justified by a lack of education among the population of the importance to conserve their water in clean pots and avoid contaminating them with animal or human feces.

Another important fact was the lack of proper sanitation, since in the homes surveyed there was no garbage collection, piped water nor sewer system. A large number of homes did not have toilets with septic tanks. We came to the conclusion that there could be a positive correlation between lack of sanitation and the occurrence of diarrhea and some intestinal parasitosis in the population, especially among children.

This study was conducted at the end of the dry season (March) and the beginning of the winter season (June), 2006. Higher bacterial densities are observed during the rainy season than during the dry season¹⁶, thus further studies are required to monitor seasonal variation of bacterial and parasite quality of ready-to-drink water of Tuparetama.

In conclusion, the results of this study demonstrate that bacterial and parasite contamination is a common occurrence in rainwater used by rural communities in Northeast Brazil, highlighting the necessity of preventive measures such as adequate and periodic rainwater sanitary monitoring to improve the local sanitary conditions and health education of the population. People confirmed their belief that they have good quality water, despite having no concern about its correct storage or its treatment.

ACKNOWLEDGMENTS

To National Council for Scientific (CNPq) by grant to the project "CONTRIBUIÇÃO PARA MELHORIA DA QUALIDADE DA ÁGUA CONSUMIDA EM COMUNIDADES DO SERTÃO DO PAJÉU" – "Contribution to improving the quality of water used in the communities of semi-arid region of Pajeú" and PROEXT - UFPE .

Received: 1 June 2010

Accepted: 22 February 2011

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Publication Dates

• Publication in this collection
  27 July 2011
• Date of issue
  June 2011

History

• Received
  01 June 2010
• Accepted
  22 Feb 2011