Occurrence of Cryptosporidium species in surface water in South-eastern Nigeria: The public health implication
C Uneke, B Uneke
concentration, oocysts, surface water
C Uneke, B Uneke. Occurrence of Cryptosporidium species in surface water in South-eastern Nigeria: The public health implication. The Internet Journal of Health. 2007 Volume 7 Number 2.
Using filtration, backwashing, concentration and modified Ziehl-Neelsen staining technique techniques water samples from major rivers serving for drinking and irrigation purposes were analyzed for
per litre of water was observed in March while the least mean monthly oocysts concentration of 83.7 per litre of water was observed in the month of April. The differences in the mean monthly oocysts concentration per litre of water was statistically significant (F-ratio=3.23,
Cryptosporidiosis caused by the coccidian protozoan parasite
Water-borne transmission is facilitated by the small size of the oocysts (3.5-5.0µm), suboptimal processing of water treatment facilities and long lasting infectivity of the oocysts in the environment (5). Numerous studies have reported the contamination of surface water by
There is paucity of information on the occurrence of
The study was conducted from December 2004 through May 2005 in Abakaliki one of the major cities in the south-eastern Nigeria and capital of Ebonyi State. The area lies approximately between longitude 8°6'6'' E and latitude 6°22'26'' N and is located on the lower belt of the Niger. The climate is tropical and the vegetation characteristic is predominantly the semi-tropical rain forest with an average annual rainfall of about 1600mm and average atmospheric temperature of 30°C. There are two distinct seasons; the wet and the dry seasons. The former occurs between April and October, while the latter takes place from November to March.
The area is traversed by a number of rivers which include Iyiudele River, Iyiokwu River, Ebonyi River and Okpuru River and form a confluence at the Southern part of the city. These rivers constitute the major sources of water supply especially to the suburbs and rural communities bordering the city. Water from these streams and rivers serve for drinking, washing, bathing and irrigation purposes for the medium and small-scale farming which is a major occupation of the people inhabiting the suburbs of Abakaliki where many varieties of the vegetables and fruits sold in the city are grown. The rivers and other water courses drain the city collecting both human and animal wastes from homes, hospitals, markets and industries and are often polluted with organic substances with higher concentrations during the dry season.
Water samples were collected from four different locations in four different rivers in the study area (Iyiudele River, Ebonyi River, Iyiokwu River and Okpuru River). At each sampling site, 50 litres of water sample was collected per week randomly from the respective water bodies in plastic containers and transported immediately to the Medical Microbiology/Parasitology Laboratory of Ebonyi State University, Abakaliki, for analysis. The sampling was carried out for the period of five months giving a total of 1,000 litres to water samples per sampling site and a total of 4,000 litres in all.
Analysis of samples was done using the techniques described in previous studies with slight modifications (15,16,17).
Differences in means were evaluated by the one-way ANOVA described previously (19). The level of statistical significance was set at 0.05.
In relation to the period of sample collection, variations in oocysts concentration were observed. Samples collected in the month of March had the highest mean monthly oocysts concentration of 226.47 per litre of water while the least mean monthly oocysts concentration of 83.69 per litre of water was observed in the month of April. The mean monthly oocysts concentrations of 124.14, 157.06, 178.8 and 156.31 were observed in December, January, February and May respectively (Table 1). The differences in the mean monthly oocysts concentration per litre of water was statistically significant (F-ratio=3.23,
The very high concentration of
It is already well established that millions of oocysts are usually excreted by an individual (approximately 106/ml of stool each day) during an acute stage of cryptosporidial infection and patients with AIDS are known to excrete approximately 1010 oocysts per day (12). Hence in the study area during the dry season, there is usually little water for flushing the human and animal faeces carrying the oocysts from the surfaces/environment into streams or larger water bodies. Therefore small volumes of water may wash this massive number into the rivers during the dry season resulting to the high concentration of oocysts at such periods (17). In addition, the ocysts are carried slowly and distributed along the water course and at the peak of the rains, they are dispersed and washed off as rivers flows downstream (5,21). This may explain the occurrence of high concentration of oocysts in this investigation during the month of March (an average of 226.47 oocysts per litre of water).
The highest concentration of oocysts was recorded in Ebonyi River, with a mean of 183.28 oocysts per litre of water. This could be because Ebonyi river is the downstream of Iyiudele River which drains the major parts of the study area and carrying most of the human and animal wastes especially wastes from the major markets (Kpirikpiri market, Eke-Aba market, Abakpa market) and from homes of people of low social and economic status living predominantly in the stems along this river course and have no proper waste disposal facilities. It is well established that there is usually high concentration of
It is important however to state that although the modified oocyst isolation technique used in this study was reasonably sensitive, the possibility of underestimation may not be ruled out. More accurate and sophisticated techniques for the isolation of
In conclusion, the presence of high concentrations of
Authors are grateful to Mr. Ogudu N. Ogudu for his role in the water sampling and analysis.