Fresh Water Snails (Bulinus and Lymnaea) in Canals in Imo State, Nigeria: Their Public Health Importance and Implications for Control

Abstract

Introduction: Researchers have emphasized the need to adopt feasible strategies that will reduce repeated human contacts with freshwater snails in contaminated water so as to protect humans against infection. This study is aimed to identify strategies that are capable of protecting humans from being infected by snails in contaminated freshwater canals along dwellings areas in Imo State, Nigeria.

Materials and Method: Freshwater snails were collected for morphological identification using long plastic spoons with the hand-picking method. The Physico-Chemical parameters of the freshwater canals were determined using appropriate instrument. A total of one thousand four hundred and nine (1409) freshwater snails were collected for the study. The snails were collected once a week for three months May, June and July 2021.

Results: The species of the 1409 snails collected were mainly Lymnaea and Bulinus. This was made up of Bulinus 533(37.8%) and Lymnaea 876(62.2%). The relative percentages of the snails collected each month were 43.9% for May; 29.9% for June and 26.2% for July. The monthly infectivity rates of the snails collected were 69.2% for May, 50.1% for June and 33.6% for July. The snails with the highest infection were in May. In all, 764 (54.2%) of the snails collected were infected. Dissolved oxygen (DO), Biological oxygen demand (BOD) and PH were found to significantly influence snail distribution in the site (p<0.05).

Also during the study, a good number of individuals including school children were observed swimming in the water canals as well as picking the snails probably for consumption. Others including women were seen washing food items, clothes, and cars as well as fetching water in cans.

Conclusion: The fact that some residents in the study areas have regular contacts with freshwater canals and the snails, suggest that a good number of them may be at risk of infections associated with Bulinus and Lymnaea snail species and their attendant pathological effects on humans. Therefore, health education that will emphasize the benefits of improved hygienic conditions around the canals as well as reduced contacts to encourage disease prevention and health promotion will be necessary. There is need to reduce contacts with the infective flukes of Bulinus and Lymnaea in fresh water canals so as to minimize the risks of their infections.