[Epidemiological study of Paragonimus sp. in south Cameroon]. / Etude épidémiologique d'une distomatose à Paragonimus sp. au sud-Cameroun.

A study was carried out in 1993 in south Cameroon in order to assess the changes in the incidence rate of human paragonimiasis, and to get information on the transmission pattern of Paragonimus sp. Two human cases have been recorded, and one dog was found infected in the Ntem Valley. The results suggest that a decrease of the incidence rate of paragonimiasis occurred in humans and animals. Paragonimus metacercariae were found in three species of freshwater crabs: Sudanonautes africanus, S. aubryi et S. granulatus, the latter being a new host. Prevalence of infection in crabs increased southerly, and significant seasonal changes were found. Two cats were infested with metacercariae from S. africanus, and studies are in progress to identify the parasite(s) at a specific level.

The dwarf river crab Liberonautes latidactylus nanoides Cumberlidge & Sachs, 1989, from Liberia--a new second intermediate host of Paragonimus uterobilateralis.

Large populations of the dwarf river crab Liberonautes latidactylus nanoides Cumberlidge & Sachs, 1989, collected from the St. Paul river at the Haindi/Mauwa focus of paragonimiasis in Liberia were examined for parasitization by the human lung fluke, Paragonimus uterobilateralis. Four specimens out of 763 L. l. nanoides proved to be positive for P. uterobilateralis (0.52%), and each of these specimens contained only 1 metacercaria. The dwarf river crab forms the basis of a seasonal commercial fishery in Liberia, and it is sold for human consumption in rural markets. However, the low levels of parasitization of L. l. nanoides, together with its limited seasonal availability make it doubtful that L. l. nanoides constitutes a public health risk to the rural population of Liberia.

Distribution of metacercariae in freshwater crabs in relation to Paragonimus infection of children in Liberia, West Africa.

An explanation was sought for the high prevalence of paragonimiasis in children in Liberia by examining possible modes of human infection from freshwater crabs. The occurrence, frequency of infection, and distribution of metacercariae of Paragonimus uterobilateralis in the freshwater crab Liberonautes latidactylus were studied. The muscles of the cephalothorax and of the legs were found to be the most frequently and most heavily infected parts of the crab. A likely risk of infection of children was considered to be the habit of chewing on, or ingesting in a raw state, the walking legs of infected crabs. Possible contamination of the hands of cooks with metacercariae from the internal organs or haemolymph of infected crabs was thought to be a minor route of infection.

Isolation of microcercous cercariae from snails caught in an endemic focus of Paragonimus uterobilateralis in Liberia, West Africa.

Microcercous cercariae have been recovered from the snail Homorus (Striosubulina) striatella RANG. which were collected in a focus of human lung fluke disease in Liberia, West Africa, and are here described. Metacercariae of Paragonimus uterobilateralis were isolated from freshwater crabs (Liberonautes latidactylus) captured at the same location, and at the same time, as the infected snails. The dimensions of the Liberian cercariae have been found to differ markedly from those of a cercaria from Cameroon previously described as that of Paragonimus africanus. The structure and dimensions of the Liberian cercariae clearly resemble those of the cercariae of other species of Paragonimus from Asia and America.