SOURCE:

Faculty: Biosences
Department: Parasitology And Entomology

CONTRIBUTORS:

Ezeagwuna, D. A.
Onyido, A. E.

ABSTRACT:

Urogenital schistosomiasis is the world’s second most debilitating disease of man. It is highly prevalent in Nigeria especially in areas where the intermediate hosts (freshwater snails) breed in waters that are contaminated by infected people.The study of bionomics of the intermediate hosts is necessary for the planning of environmental control. This study is aimed at investigating the ecology of freshwater snails in Obutu and Iyiegwu lakes andepidemiology of urogenital schistosomiasisin Omogho and Ndikelionwu communities of Orumba-North Local Government Area between August 2014 and July 2015. Monthly collections of freshwater snails were done using scoop netsat different points of the lakes and hand-picking methods with hand gloves. Snails were picked from under leaves of floating vegetation, floor of water-contact areas with vegetation and floor of water-contact areas without vegetation.The snails were exposed under the sun to determine their infectivity (cercaria shedding) and subsequently crushed between slides and examined under the microscope for presence of cercaria. The lake water was collected into sterile containers monthly and transported to the laboratory in a cold chamber for physico-chemical properties using the methods described by the American Public Health Association. Biotic factors including predators and vegetations were determined through visual observations of the lakes and environs. Furthermore, a cross-sectional sample size of 524 participants including school children and adults aged 5-60 years was randomly selected from the randomly selected villages in the study area. Urine samples of these individuals were collected into a wide-mouthed transparent universal container and examined for schistosome eggs using microscopy. People’s perceptions as well as attitude and practice about urogenital schistosomiasis infection were determined usingpre-tested questionnaire. Data collected were analyzed using Student T-test and Analysis of Variance to compare percentage prevalence and mean egg output while Correlation Coefficient was used to determine relationship between properties of water and abundance of snails. Intensity of infection was also calculated. Results showed that a total of 1,631 snails of which 1,117(68.49%) and 514(31.51%) were recorded from Iyiegwu and Obutu lakes respectively. Two snail species, Bulinus globosus 26(1.59%) and Pila ovata 1605 (98.41%) constituted the species identified from the lakes. None of the snails was found to shed cercariae. Students t-test showed that Pila spp (98.41%) was significantly higher (P<0.05) than B. globosus(1.59%). More Pila spp 130 (26.2%) was collected during the rainy season (July) and more Bulinus 13(76.5%) was collected during the dry season (January) in Obutu lake. In Iyiegwu lake also, more Pila spp 228(20.6%) was collected during the rainy season in July while Bulinus spp was collected more 3(33.3%) during the dry season (February).Physico-chemical propertiesof the water included pH (4.13-6.77), turbidity (4.0-8.46 Nephelometric Turbidity Unit), conductivity (10-180 uS/cm), total dissolved solids (28.85-286.66mg/l), total hardness (60-250mg/l), calcium and magnesium hardness (20-150 and 35-100mg/l, respectively), nitrate and nitrite concentration (0.413-13 and 0.11-0.20parts per million (ppm), respectively), total suspended matter (10-40mg/l), total and faecal coliform (3-15 and 1-8most probable number/100ml, respectively). As pH of the lake increases, the abundance of snail also increases but there was no significant correlation (P>0.05) between pH and snail abundance. Turbidity (r= 0.609),magnesium hardness (r= -0.677), nitrite concentration (r= 0.696) and total coliform (r= 0.790)were significantly correlated at 0.05 levels of significance with theBulinus population in the lakes. Biotic factors recorded included fishes, turtles, squirrels, lizards, cattle, oil palm trees, cassava plants, bambooes and humans performing some activities. Twenty plant species of which Pistia stratiotes, Commenlina benghalensis, Ludwigia spp, Sida acuta, wildspeciesofIpomea among othersproviding both shelter, food and oviposition sites for the snails were also recorded. Overall prevalence of infection in the area was 88(16.8%) with an overall mean egg output of 17.05eggs/10ml urine. The prevalence in Omogho 62(25.3%) was significantly higher (P<0.05)than Ndikelionwu 26(9.3%) community. Participants of age group 16-26years were more infected 16(29.6%) and males 59(20.3%) were more infected than females 29(12.4%). Prevalence was significantly different in age groupsand gender (P<0.05). Participants’ knowledge of the name of the disease was high 443(84.5%) but low in knowledge of mode of transmission90(17.2%) and only 166(31.68%)reported that visit to the hospitalis an option for treatment when infected. Schistosoma intermediate snail host (Bulinus globosus)was collected from the lakes, though in low numbers. The study established that urogenital schistosomiasis is prevalent in Omogho and Ndikelionwu communities and the physico-chemical and biological properties of the lakes influenced the availability of snail intermediate host. Some human contact activities observed in the lakes (swimming, washing breadfruits, washing clothes, fetching water, fishing and washing of vehicles) constantly expose the people to infections and re-infections. Health education is recommended to enlighten the populace on sources of infection, prevalent and treatment of the disease. Government assistance is also recommendedthrough provision of clean water for the community to reduce water body-human contact activities.