[On the distribution of the lung flukes, Paragonimus africanus and P. uterobilateralis, in the South West Province of Cameroon and in Eastern Nigeria as determined by examination of the intermediate crab hosts for infection with metacercariae (author's transl)].

During 1973-75 the distribution of the lung flukes, Paragonimus africanus and P. uterobilateralis, was studied in South West-Cameroon and in Eastern Nigeria, on the basis of parasitological examinations of the intermediate crab hosts Sudanonautes africanus, S. pelii, and S. aubryi, belonging to the family Potamonidae. 1000 freashwater crabs from 80 localities were examined for prevalence and intensity of infection with Paragonimus methacercariae. In Cameroon S. pelii was found to be a new intermediate host for P. uterobilateralis, and S. aubryi a new host for P. africanus. The morphology, behavior, and habitats of the crabs are summarized. In Eastern Nigeria only metacercariae of P. uterobilateralis were found. The main endemic area was located in the basin of the upper Imo River. Outside this area infected crabs were found only in and around Arochukwu, in the lower tributaries of the Cross River. This distribution differs from that given by Nwokolo (1974), which was based on the origin of clinical cases. These differences are discussed. In South West-Cameroon both Paragonimus species were found. The highest prevalence and intensity of metacercariae of P. africanus was seen in certain tributaries of the Mungo River in the area of Lower Bakossi. Proceeding northwards towards Mamfe, infections with P. africanus decreased steadily, whereas infections with P. uterobilateralis increased. On the upper reaches of the Cross River from the region around Mamfe and extending as far as the Nigerian fronter at Ekok, the crabs were infected exclusively with P. uterobilateralis. The unexplored mildle reaches of the Cross River may form a bridge between the endemic areas of this lung fluke in Nigeria and Cameroon.