The Epidemiology of Pulmonary Paragonimiasis in Cross River Basin in Nigeria: Update on infection prevalence and distribution of the snail and crab intermediate hosts.

Deep sputum samples from 2400 school children aged 5-14 years old, in eight districts in Cross river basin, Nigeria were examined for Paragonimus ova. A total of 246 sites along streams and rivers including the Cross River itself were also surveyed for snail and crab intermediate hosts of Paragonimus, and their infection rates were determined. The overall prevalence of pulmonary Paragonimus infection in schoolchildren in the area was 14.4% (346/2400). Six foci of the infection were identified at Oban, Ugep, Ikom, Obubra, Yala, and Ogoja districts. The intensity of the infections (number of ova per 5ml. Sputum) were generally low. Of the 346 infected school children, 249 (72.0%) had less than 50 ova of Paragonimus in 5ml sputum, and 74 (21.4%) had between 50 and 100 ova of Paragonimus in 5ml sputum, while 23 (6.6%) had over 100 ova of Paragonimus in 5ml sputum. Two snail hosts of Paragonimus were encountered in our survey. These were Potadoma freethii and Afropomus balanoides. P. freethii was more widely distributed than A. balanoides and was the only snail species naturally infected with Paragonimus (6.1%). Three crab species associated with Paragonimiasis transmission were also collected. These were Sudanonautes aubryi, Sudanonautes africanus and Sudanonautes pelli. These three crab species were widely distributed in the basin. However, only S. africanus (5.0%) was found to harbour Paragonimus infection. The results of this study indicate the growing public health threat posed by Paragonimiasis in Cross River basin in Nigeria. A combination of chemotherapy, to bring relief to persons already afflicted by the disease, and public health education related to Paragonimiasis transmission to increase awareness of the infection in the area is recommended as the best approach to check the infection in the basin. Key Words: Pulmonary Paragonimiasis, Cross River Basin, Distribution, Intermediate Hosts, Prevalence [Mary Slessor Jnl of Medicine Vol.3(1) 2003: 5-12