Clams are an important source of economic incomes and animal protein source for population of sub-Saharan Africa countries, especially in Cameroon. Unfortunately, parasitism is a serious threat to the economy and health risk to these populations. The present study aimed at determine parasite diversity and intensity as well as the impact of this parasitism on E. radiata populations in the Lower Sanaga river, Cameroon.
All main groups of parasites (i.e., protozoans, trematodes, cestodes and nematodes) were found in this study, and this is consistent with works of Adeyemo et al. who reported the same groups of parasites in the Nun River in Nigeria. The natural capacity of this bivalve species to burrow and filter water expose it to infection with these above mentioned groups of parasites which also live in the aquatic environment of E. radiata clam. In general, clams are victims of a large number of parasites that cause a mass mortality and significant economic losses [7; 8; 9]. Marine bivalves are often served as a host of metazoan parasites or symbiosis such as trematode, cestode, nematode and copepode. Such metazoans have been identified from various marine bivalves including oysters, mussels, cockles and clams [20; 21]. Several authors have reported on the occurrence of trematode and cestode in clams in Jeju Korea and Ariake Bay, Japan [22; 23]. .
The parasitofauna is mainly dominated by nematodes while protozoans were found with the lowest prevalence. This pattern is in line with that of Adeyemo et al. . In addition, a significant difference was found in prevalence of the groups of parasites between the two study sites. This discrepancy is likely the fact of a geographic area-specificdistribution of the groups of parasites. The environment conditions are well known shape the distribution of numerous living organisms including parasites. High number of trematodes may affect reproductive processes and possibly retarding gonadal development . The authors found that mite and trematode abundance were greater in smaller freshwater mussels .
Values of parasitological clues at Egeria radiata (Lamarck, 1804)
Depending on the area, there was a higher average specific wealth in Maldjedou (0.75 ± 0.51) than in Bolounga significantly (p-0.0033). That parasite indexes were higher for larger clams and could be explained by higher filtration rates. Furthermore could be explained also by longer exposure to infective particles . In the present study, although clam shell length was 5.2 ± 1.4 cm on average at Maldjedou compare to 4.5 ± 1.2 cm at Bolounga. However, the maximum value of 3 was obtained for the entire population, as well as in Bolounga. This could be explained by the fact that in Bolounga the parasitic species here would have been more diverse than in Maldjedou and thus being a filterer more bioaccumulated of parasitic species. This result is lower than that of Adeyemo et al.  having found a value of 4 in the same host Galatea paradoxa (Born, 1778). The study showed a higher average specific richness associated with Bulging significantly (p-0.0035). The specific richness in relation to the morphometric parameters depending on the zones, revealed that the Bulging of clams in Bolounga would be the only parameter related to the specific parasitic richness. This could be explained by the fact that according to authors  molluscs are bioaccumulators that concentrate many parasitic species present in the water all around it. Acquisition of parasite infective stages can be increased for larger bivalves with high filtration capacities.
Parasite Intensity and Abundance
The overall prevalence of infection was 74.5 %. This value is higher than the 50% threshold used to identify the presence of dominant species according to authors .Similar prevalence values were reported in Nigeria . This high value of infection burden could be due to anthropic activity as riverside residents used to dump wastes of varied nature, and parasitized feces, and thus contribute to the contamination of the aquatic milieu of E. radiata. As above stated, clams are important filterer organisms, and as a consequence are exposed to infection when filtering parasitized water. Parasite indexes were below 10 in the study sites, thereby implying that majority of parasite species have a very low mean intensity of infection . A similar result was reported in Nigeria, where the authors found abundance values of 1 and 1.09 in their study sites . Also prevalence and infection intensities of parasites at Bolounga were comparatively lower than the prevalence and intensities reported from Maldjedou, suggesting that overall health condition of Bolounga E. radiata clams was graded to be good.
Existing relationship between some biotic parameters of bivalve and Egeria radiata parasitolofauna.
Regarding the influence of parasitofauna on metric parameters, only the Bulge was influenced for clams parasitized at Cestodes (p-0.028) and parasitized to nematodes (p-0.017). This can be explained by the fact that helminths in general and especially these two classes contain endoparasites and mesoparasites that would have a direct influence on the weight of the soft body of the bivalve. Therefore, an influence of pathology on the metric parameters of the clam  to the example of the Egeria radiata Bulge. Parasite prevalence was higher in adults than in juveniles and could be explained by higher filtration rates and also by longer exposure to infective particles . Condition index at Maldjedou show that despite low infection intensity an overall infection, Bolounga have better condition with E. radiata bivalves. The low infection intensity at two stations could be associated with a low density of clam and this index is positively correlated with the density of host organisms and environmental factors such substrate of area as bed [9;28].
However, including the group of parasites of unidentified species, significant associations were observed with metric parameters such as the weight of the left shell (p-0.036), the length of the shell (p-0.007), and the height of the shell (p-0.018). This can only be explained after extensive study on the identity of unidentified parasites.