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Table of Contents
ORIGINAL ARTICLE
Year : 2015  |  Volume : 14  |  Issue : 1  |  Page : 32-38  

Microbiological assessment of well waters in Samaru, Zaria, Kaduna, State, Nigeria


1 Department of Textile Science and Technology, Faculty of Science, Samaru Zaria, Kaduna, State, Nigeria
2 Department of Medical Microbiology, Faculty of Medicine, Ahmadu Bello University, Samaru Zaria, Kaduna, State, Nigeria

Date of Web Publication7-Jan-2015

Correspondence Address:
Fatima J Giwa
Department of Medical Microbiology, Ahmadu Bello University, Samaru, Zaria, Kaduna, State
Nigeria
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/1596-3519.148732

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   Abstract 

Background: Majority of the human population in semi-urban and urban areas in Nigeria are heavily reliant on well water as the main source of water supply for drinking and domestic use due to inadequate provision of potable pipe borne water. These groundwater sources can easily be fecally contaminated and thus, increase the incidence and outbreaks of preventable waterborne diseases. This study was carried out to determine the bacteriological quality of some well waters in Samaru, Z.
Materials and Methods: Samaru, Zaria located in Northern Nigeria, is a semi-urban university satellite town blessed with abundant ground and surface water. Five sampling sites were randomly selected for this study. A total of 10 samples: Two from each of the sites were collected fortnightly for 1 month (May-June, 2013). Samples were analyzed using presumptive multiple tube fermentation and confirmatory tests for total and fecal coliforms. The well water samples were also cultured for Salmonella, Shigella, and Vibrio chole.
Results: The total coliform count for all the samples analyzed was >180+/100 ml. All the well water samples from the study locations were contaminated with one or more bacterial pathogens, Escherichia coli 20%, Klebsiella pneumoniae 100% and Proteus mirabilis 40%. Salmonella, Shigella, or V. cholerae were not isolated from any of the well water samples.
Conclusions: The results from this study showed contamination of all the wells studied with fecal coliforms thus, indicating the possible presence of other enteric pathogens and a potential source for waterborne disease outbreaks. Well water in Samaru is not safe for drinking without additional treatment like disinfection or boiling. Periodic testing and constant monitoring of well waters should also be done to meet up with the World Health Organization Standards in the provision of safe, clean drinking water .

   Abstract in French 

Résumé
Contexte:
Majorité de la population humaine dans les zones urbaines et semi-urbaines au Nigeria sont largement tributaire de l'eau de puits comme la principale source d'approvisionnement en eau pour usage domestique boire en raison de la disposition inadéquate de pipe potable l'eau à la charge. Ces sources d'eau souterraine peuvent être facilement contaminés matières fécales et ainsi, augmentent l'incidence et les éclosions de maladies d'origine hydrique. Cette étude a été réalisée pour déterminer la qualité bactériologique des eaux bien Samaru, Z.
Matériel et Méthodes: Samaru, Zaria, situé au nord du Nigeria, est une ville de satellite de semi-urbaines universitaire dotée d'abondantes surface et des eaux.Cinq sites d'échantillonnage ont été choisis au hasard pour cette étude. Un total de 10 échantillons : deux pour chacun des sites ont été prélevés tous les quinze jours pendant 1 mois (mai - juin 2013). Échantillons ont été analysés en utilisant plusieurs présumés tube de fermentation et des tests de confirmation pour les coliformes totaux et les. Les échantillons d'eau de puits ont été également cultivées pour Salmonella, Shigella, et Vibrio chole.
Résultats: Le nombre de coliform total pour tous les échantillons analysés a été > 180 + / 100 ml. Tous les échantillons d'eau de puits aux endroits de l'étude ont été contaminés par une ou plusieurs bactéries pathogènes, Escherichia coli 20 %, Klebsiella pneumoniae 100 % et Proteus mirabilis 40 %. Salmonella, Shigella, ou V. cholerae n'étaient pas isolées de n'importe lequel des échantillons d'eau bien.
Conclusions: Les résultats de cette étude ont montré la contamination de tous les puits étudié avec les coliformes fécaux ainsi, indiquant la présence possible d'autres pathogènes entériques et une source potentielle de flambées de maladies d'origine hydrique. L'eau de puits en Samaru n'est pas sans danger pour boire sans traitement supplémentaire, comme la désinfection ou la faire bouillir. Des essais périodiques et une surveillance constante des eaux bien devraient également être faits pour rencontrer les normes de l'organisation de santé mondial dans la fourniture d'eau potable salubre et propre.
Mots-clés: Fecal coliform, évaluation microbiologique, maladies d'origine hydrique, les eaux bien

Keywords: Fecal coliform, microbiological assessment, Samaru-Zaria, waterborne diseases, well waters


How to cite this article:
Aboh EA, Giwa FJ, Giwa A. Microbiological assessment of well waters in Samaru, Zaria, Kaduna, State, Nigeria. Ann Afr Med 2015;14:32-8

How to cite this URL:
Aboh EA, Giwa FJ, Giwa A. Microbiological assessment of well waters in Samaru, Zaria, Kaduna, State, Nigeria. Ann Afr Med [serial online] 2015 [cited 2020 Oct 20];14:32-8. Available from: https://www.annalsafrmed.org/text.asp?2015/14/1/32/148732


   Introduction Top


Water is essential for the survival of every form of life and the need for water is constantly increasing due to high rates of population growth and urbanization. However, the increased demands on water for drinking, domestic agricultural, and industrial purposes are not commensurate with water availability thus, posing significant risks in maintaining acceptable water quality. [1],[2]

Groundwater represents an important source of drinking water and constitutes the largest source of dug well water. [3] Water from these shallow and deep wells is often of better quality than surface open water sources, if the soil is fine-grained and its bedrocks do not have cracks, crevices, and bedding plants, which permit the free passage of polluted water. [4],[5] The availability and purity of groundwater are affected by location, construction, and operation of the wells. [6] It is often assumed that natural, uncontaminated water from deep wells is clean and healthy, and this is usually true with regards to bacteriological composition. [7]

However, bacterial pollution of water sources may occur and is mostly derived from watershed erosion as well as drainage from sewage, swamps, or soil with a high humus content due to lack of compliance to standard guidelines guiding groundwater exploration or well construction. [8] Such suspected water sources cannot be used without caution for human drinking purposes due to the inherent health risks. [9],[10],[11] The drinking qualities of dug well water are largely dependent on the concentration of biological, chemical, and physical contaminants as much as environmental and human activities in such respects. [12]

In many developing countries and including Nigeria, treated pipe borne water availability is limited and inadequate for the teeming population, thus, an increasing number of people in semi-urban and urban areas in Nigeria depend on dug wells and water vendors for water supply. [13]

Bacterial contamination of drinking water is a major public health problem worldwide, because this water can be an important vehicle of diarrheal diseases, thus, the need to evaluate the microbiological quality. [14] Monitoring the microbiological quality of drinking water is done through laboratory testing for the coliform group. The term "total coliforms" refers to a large group of Gram-negative, rod-shaped bacteria that share several characteristics. The group includes thermotolerant coliforms which are of fecal origin, found in the intestines of humans and warm-blooded animals, as well as the environmental species that are naturally found on plants, soil, and water. The thermotolerant coliforms are widely used as microbiological parameters indicating fecal contamination while total coliforms serve as a parameter to provide basic information on water quality. [15] The need to assess the quality of water from some of these alternative sources is imperative because they have direct effects on the health of individuals.

The presence of fecal coliform in water may indicate that the water has been contaminated with fecal material of humans or other animals. Groundwater in a properly constructed well should be free of coliform bacteria. Fecal coliform bacteria can be found in wells through direct discharge of waste from mammals and birds, agricultural and human sources. This could also happen due to poor construction or cracks in the well or through runoffs from wooded areas, pastures, feedlots, septic tanks, and sewage plants into streams or groundwater. [16] Regular monitoring of the microbial quality of drinking water is an essential step in ensuring the safety of drinking water. [17]

The main aim of this study was to assess the microbiological quality of well waters in Samaru, Zaria and find out the degree to which they meet the World Health Organization (WHO) standards.


   Subjects and Methods Top


This study was carried out in Samaru, Zaria, Sabon Gari local government area of Kaduna state in North central Nigeria. Samaru is situated on latitude 11°09'30.99"N and longitude 7°38'15.68 to 7°39'20.68"E at an altitude of 550-700 m. It lies within the Northern Guinea savanna vegetation belt. The climate of this zone is characterized by a dry season of 7 months duration from mid-October to mid-May and an annual rainfall of 1094.34 mm [43.08°]. The soil is mainly accumulated clay lying between a depth of 36 cm and 119 cm.

Samaru-Zaria located in Northern Nigeria, is a semi-urban university satellite town blessed with abundant ground and surface water. [18] In spite of its potentials for good groundwater storage, the poor water distribution and supply have made this community reliant on well water for drinking and other domestic purposes. [19]

Sampling sites

Samaru village was zoned into five areas based on population density and socioeconomic status of the residents. Sampling wells were randomly selected from each of these areas based on accessibility and usage. A total of 10 samples: Two from each of these sites were collected in Samaru namely: JAWOM area, Oando Filling Station, Hayin Dogo, Leather Research Institute, and Samaru Market. Samples were collected every fortnight for 1 month (May-June 2013).

Three of the wells under study are privately owned while two are public wells. They are all usually accessible to the general public. The privately owned wells were not properly covered, while the others were not covered at all. Drawing of water from these wells was usually done using black rubber containers with ropes attached to them, and some were tied directly to the well cover. These containers were not regularly washed and were slimy with sediments in them. Often, they were left on the ground and came in direct contact with soil. Containers to draw and fetch water were also brought by individuals. The wells were constructed with concrete, though all had cracks in their walls and were on average about 5 m deep.

Collection of water samples

Water samples were collected aseptically in 250 ml sterile bottles tied with a strong string to a piece of metal (about 500 g) as the weight. The bottle cap was aseptically removed, and the weighted bottle lowered into the well to a depth of about 1-2 m. The bottle was brought up to the surface and covered with the bottle cap aseptically, when no air bubbles were seen inside. Samples were labeled and transported in ice packs to the laboratory within thirty minutes of collection and examined for turbidity, color, odor, taste. They were analyzed within 2 h of collection in the Medical Microbiology Laboratory of Ahmadu Bello University Teaching Hospital, Zaria.

Microbiological examination

Multiple tube fermentation technique/ (MPNMost Probable Number). The technique used for water analysis was the MPN (American Public Health Association 1998). [20] A total amount of 105 ml water sample was taken from each well water sample as one 50 ml, five 10 ml and five 1 ml amounts and inoculated into bottles of sterile double strength MacConkey broth of the same amount, each containing an inverted Durhams tube for gas collection and detection. This was incubated aerobically at 35°C for 18-24 h and served as the presumptive test for total coliform. After incubation at 37°C, the number of bottles in which lactose fermentation with acid and gas production had occurred was counted. Lactose fermentation and acid production were evidenced by a change in the color of MacConkey broth from purple to yellow and gas production was seen by the displacement of broth in the Durhams tube with bubble. [21],[22] Using the McCradys probability tables, the MPN of coliforms in the 100 ml well water sample was estimated. [22]

Confirmatory test

In the confirmatory test for fecal coliform, a loopful of broth from the positive tubes in the presumptive test was transferred into elevated coliform broth and incubated at 44.5°C for 24 h. Production of gas in the tube after 24 h was positive. After incubation at 44.5°C, there was gas production in some of the tubes incubated at 44.5°C, the number of positives were recorded and compared with the MPN table. A loopful of broth from the positive tubes was also streaked on MacConkey agar and incubation at 35°C for 18-24 h yielded growth. [21],[22] The isolates were further identified by colonial morphology, Gram-stain, motility, and Biochemical tests.

Identification of isolates

Positive tubes of the presumptive and confirmatory test were subcultured on MacConkey agar for the enumeration of  Escherichia More Details coli and other enteric coliforms. All the inoculated media were incubated aerobically at 37°C for 24 h, after which the isolates were further characterized by a combination of colonial and morphological characteristic on solid media, Gram-stain as well as standard biochemical tests for oxidase production, motility, Triple Sugar Iron agar test, citrate utilization test, urease production, and indole test as described by Winn et al. [23]

Detection of Samonella typhi, Shigella and  Vibrio cholerae Scientific Name Search  isolation of  Salmonella More Details typhi and Shigella

One ml of each water sample was inoculated into 5 ml of selenite F enrichment broth and incubated at 37°C for 8 h. It was then inoculated on Salmonella - Shigella agar and incubated for about 24-48 h at 35-37°C. [23]

Isolation of Vibrio cholerae

One ml of each water sample was inoculated into 5 ml of double strength alkaline peptone water and incubated for 6-8 h. It was then inoculated on thiosulfate citrate bile salt agar and further incubated at 37°C for 24-48 h. [23]


   Results Top


[Table 1] shows the presumptive coliform count with the MPN (MPN/100 ml). The total coliform count was >180+/100 ml for all the well water samples tested. This translates to a high coliform count in all the well water samples analyzed. All the wells had cracks in their walls and were either uncovered or not properly covered, and the containers used for fetching water were not clean.
Table 1: Presumptive coliform count from well water

Click here to view



   Discussion Top


Water is one of the most important vehicles for the transmission of infectious diseases and fecal contamination of water sources particularly in developing and underdeveloped countries has been well-documented. [24],[25],[26]

The MPN per 100 ml for all the well water samples studied was 180+/100 ml. This exceeded the guideline values recommended in accordance with the WHO international standards, which states "no sample should contain fecal coliform or E. coli", and there should be "no total coliform/100 ml water sample".

The high coliform count observed in this study compares with similar studies done by Sagamu and Lagos [13],[27] , respectively where they analyzed well water samples and found the MPN to be high. This high count however, does not necessarily indicate recent water contamination by fecal waste, since total coliforms includes both environmental and thermotolerant (fecal) coliforms. In extreme cases, it may be associated with a low, or even zero, count for thermotolerant coliforms [22] which may be caused by entry of soil or organic matter into the water. However, the presence or absence of these bacteria in treated water is often used to determine whether water disinfection is working properly. [28]

This study further revealed [as shown in [Figure 1] the presence of one or more bacterial pathogens in all the well waters sampled in addition to a high total coliform count. K. pneumoniae was isolated in all the sample locations (100%), thermotolerant E. coli was isolated in the samples from location III in addition to K. pneumoniae, while Proteus vulgaris was isolated in the samples from locations IV and V in addition to K. pnemoniae. Salmonella, Shigella, or Vibrio were not isolated from any of the well water samples. The presence of thermotolerant E. coli and K. pneumoniae indicated fecal contamination of ground water with human or animal sewage. This poses a potential hazard of transmission of waterborne diseases by these pathogenic organisms.
Figure 1: Klebsiella spp. was found in all the well water samples in addition to Escherichia coli, which was found in sample III and Proteus spp. which was found in samples IV and V

Click here to view


Similar microorganisms have been isolated from studies done in Lagos and Ibadan where it was found that well water used for drinking and cleaning purposes were contaminated with pathogenic organisms. [27],[29] This finding also corroborates other studies done on well water in other countries. [30],[31],[32]

Escherichia coli is a fecal coliform commonly found in the intestines of animals and humans, that are associated with human or animal wastes. [33] The presence of E. coli in water is a strong indication of recent sewage or animal waste contamination and suggests that other disease-causing bacteria, viruses, protozoa may likely be present. [33]

Escherichia coli strains O157:H7 and E. coli O111 cause bloody diarrhea indistinguishable from hemorrhagic colitis. Between 2% and 7% of cases can develop the potentially fatal hemolytic uremic syndrome, which is characterized by acute renal failure and hemolytic anemia. Children under 5 years of age are at most risk of developing hemolytic uremic syndrome. [34]

Waterborne transmission of pathogenic E. coli has been well-documented for recreational waters and contaminated drinking-water. [33],[34] A well-publicized waterborne outbreak of illness caused by E. coli O157:H7 and Campylobacter jejuni occurred in the farming community of Walkerton in Ontario, Canada. The outbreak led to 7 deaths and more than 2300 illnesses. [35],[36]

It is desirable for water used for drinking purposes not to contain any organism of faecal origin. [37] The presence of E. coli in the well sample renders the water unsuitable for human consumption without disinfection, according to the WHO guidelines for drinking water quality. [38]

Klebsiella spp. was isolated in all the well water samples. It is a natural inhabitant of many water environments, and may multiply to high numbers in waters rich in nutrients, such as pulp mill wastes, textile finishing plants, and sugar-cane processing operations. [34]

Klebsiella spp. are thermotolerant coliforms which are also excreted in the feces of many healthy humans and animals, and are readily detected in sewage-polluted water. [39],[40] Their presence signifies possible fecal contamination and the likely presence of other pathogens. Klebsiella spp. are however, not considered to represent a source of gastrointestinal illness in the general population through ingestion of drinking-water. [39],[40]

The Proteus spp. isolated in well water samples in study sites 3 and 4 constituted 40% of the isolates. Proteus spp. are members of the enterobacteriaceae most commonly found in the human intestinal tract, but they can also be found as natural habitants of soil and water. Their presence also indicates possible fecal contamination.

These pathogens may pose a special health risk for infants, young children, and people with severely compromised immune systems. [33]

The presence of coliforms in a well could be due to leakage of surface water into the well which occurs if rain runoff makes its way into the well due to poor construction or cracks in the well and this was observed in all the wells in all the locations. Three out of the five wells were not well covered, and two were not covered at all. Well three which isolated E. coli was one of the uncovered wells. The openness of this well could have resulted in contamination with particles in the vicinity of the surface wells from the surroundings, especially in areas where the sanitary conditions are poor with the presence of livestock, grazing, or domestic animals.

The location of septic tanks close to wells could also result in leakages or seepages of fecal material into the wells with contamination of the ground water. This was clearly illustrated in a study done in Palm bay Florida, USA [41] which examined the seasonal correlation of well contamination and septic tank distance, and found a significant correlation between increasing coliform and decreasing the distance between wells and septic tanks. In the USA, septic tanks rank the highest in terms of untreated waste water discharged into ground water and are the most frequently encountered source of groundwater contamination. [42] Seepage from septic tanks and wastewater discharged to the soil might also in some locations contribute to the deterioration of both the chemical and the bacteriological quality of groundwater. [43],[44] Fetching water from wells with dirty containers, is a common practice observed in all the study locations and may also be a source of contamination. The presence of coliforms in drinking water could also indicate the absence of or inadequate treatment process. [31] This is not surprising as most wells do not receive any disinfection treatment before consumption in most areas in the country. Our sample sites did not receive any form of disinfection treatment. Other enteric pathogens such as Salmonella, Shigella, or Vibrio cholerae were not isolated from any of the well water samples.


   Conclusion Top


The present study showed contamination of all the well water samples with fecal coliform thus, making the water unsafe for human consumption and potential health risk. Disinfection such as boiling, chlorination, using ultraviolet rays or ozonation is recommended before consumption and use of the water for drinking and domestic purposes.

The National Environmental Standards and Regulation Enforcement Agency, The Nigerian Industrial Standards Organization and other regulatory bodies responsible for well construction and water quality must take necessary steps to ensure proper siting, construction, and maintenance of wells to minimize contamination.

Periodic assessment of well water quality should be done routinely to eliminate or reduce the health risks on individuals and communities as a whole.

 
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