Nematode Parasites of Vertebrates: Their Development and Transmission

Synopsis of Digenetic Trematodes of Vertebrates

The diversity of nematodes infecting amphibians is understudied in tropical Africa and unknown in Rwanda. Diversity assessment is hampered by the fact that species descriptions refer mostly to morphological features that are unlinked to DNA sequences of marker genes available in public databases. In this paper, we explore the abundance and diversity of parasitic nematodes in reed frogs Hyperolius kivuensis (n = 115), H. parallelus (n = 45) and H. viridiflavus (n = 100) collected in Rwanda. Five nematode species were identified morphologically as Orneoascaris chrysanthemoides, O. schoutedeni, Gendria leberrei, Aplectana chamaeleonis and Rhabdias collaris. Corresponding DNA sequences of 18S and COI genes were determined and subsequently deposited in GenBank. Aplectana chamaeleonis showed the highest prevalence (8.7%), but O. chrysanthemoides the highest mean intensity of infection (6.0) and largest number (24) of individuals in H. kivuensis. To the best of our knowledge, all amphibian hosts are new records for these nematode species, which are known to infect a wide range of amphibian and reptile species. Our findings suggest that nematode diversity is probably lower than previously assumed due to low host specificity. As morphological species identification is often challenging, our data facilitate molecular identification of adult and specifically larval nematodes found in amphibians of Sub-Saharan Africa.

https://www.mdpi.com/1424-2818/12/7/265/pdf

Molecular Diversity of Nematode Parasites in Afrotropical Reed Frogs (Hyperolius spp.)

In this study is made an ecological analysis of the species composition, structure of the helminth community and the invasion degree of Bufo bufo in different habitats in the National Park «Smolny» (Republic of Mordovia, Russia). In 2018–2019, they were collected in five biotopes with different spawning water bodies. Nine helminth species were found, including five Trematoda species and four Chromadorea (Nematoda) species. There are two groups of species. The first of them develops on terrestrial nematodes Rhabdias bufonis, Oswaldocruzia filiformis, Oxysomatium brevicaudatum, rather common, regardless of the habitat, with a high degree of invasion and dominating in the helminth community. The species of the second group develop in aquatic nematode Cosmocerca ornata, as well as trematodes which are rarer, locally and with a low infection rate. They are typical parasites of green frogs (genus Pelophylax). The diversity of helminthes and the structure of their component community depend on the type, nature of the spawning water body and the presence of green frogs. Individuals of B. bufo, spawning in stagnant water bodies where green frogs live, have a more diverse helminth species composition, because there are helminths of the second group, whose development is related to the aquatic environment. The structure of their community is more complex. Bufo bufo, when using flowing water bodies without green frogs for spawning, has a depleted helminth composition and a simplified structure of their community. The obtained results have demonstrated the influence of one allotopic amphibian species on the formation of helminth community of another species under conditions of temporary syntopic occurrence.

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Ecological analysis of the helminth fauna in Bufo bufo (Amphibia: Anura) from various habitats

Termites (Order Isoptera) are eusocial insects that are of great benefit and economic importance to humans. Despite its benefits and economic attributes to humans, it accounts for serious damage on buildings in Nigeria especially in the rural areas. The aim of this study was to collect preliminary data on termite infestation of the buildings in Ase, a local community in the Niger Delta region of Nigeria. Data was collected by direct observation of termites on the buildings, and a structured questionnaire was presented to respondents in houses with visual signs of infestation. Samples of termites were collected from parts of the houses with mud tubes or nests. A total of 106 houses were inspected with 35.85% infested with termites. The termites found were two species of Amitermes, one of Microcerotermes, three of Nasutitermes, two of Neotermes, and one of Odontotermes. Most infested homes (71%) were graded as moderate, severely damaged, and collapsed revealing a major problem. Percentage infestation of wood services revealed door frames 62.5% and wall (mud tubes) 87.75%, floor 18.85%, logs outside the house 56.25%, windows and roof 43.75%, ceiling 18.75%, and bathroom, furniture, and kitchen 6.25%. Respondents were 30–90 years old and did not attribute mud tubes to termite infestation. Seventy-two percent of the buildings were less than 60 years, and preventive measures used by respondents were Solignum and used engine oil. Most of the buildings were severely infested, and a < 2-year-old house showed visible signs of slight termite infestation. This study clearly demonstrates the level of termite infestation in Ase and the need for better control measures and increased awareness for early detection.

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Studies on termite infestation of buildings in Ase, a rural community in the Niger Delta of Nigeria

Summary The parasitic infections of 125 anurans belonging to 13 taxa from Ase community in Delta State in the Niger Delta of Nigeria was investigated. An overall prevalence of 77.6% was recorded and the 32 parasites recovered included one pentastomid, four cestode, four monogenean, ten digenean and thirteen nematode taxa. Among the anurans examined, Ptychadena bibroni harboured the highest number of parasites. Most of the parasites encountered were adults but some occurred as larvae, which either used the amphibians as intermediate or transport hosts. Hylarana galamensis is considered an accidental host for the larval brachylaimid trematode and, a new host record for the larval strigeiod while Polystoma galamensis infection of this frog is made for the first time outside the savannah biotope. Hymenochirus sp. is a new host record for Progonimodiscus colubrifer. Two Foleyellides spp., one occurring in Hyperolius concolor, Afrixalus fulvovitattus and Sclerophys regularis and the other in H. galamensis occur in the study area.

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Parasitic infections of anurans from a freshwater creek community in Delta State, Niger Delta of Nigeria

The parasitic infections of anurans from three biotopes (lowland forest, freshwater swamp and brackish water swamp) in Rivers State, Nigeria were investigated. A total of 94 anuran specimens were examined; 32 from the lowland forest, 28 from the freshwater swamp and 34 from the brackish water environment. Of the three biotopes, amphibians from the lowland forest harboured more parasite species. In total, 24 parasite species were recovered, including a pentastomid; larval  acanthocephala; one cestode; one monogenean; sevendigeneans and thirteen nematode species. Only five of the 24 parasite species recovered were common to anurans from the three biotopes. Others were either restricted to one ecological habitat or were also found in hosts from a second habitat. A form of association seems to exist between ciliates and the Cephalochlamys compactus recovered from Hoplobatrachus occipitalis collected from the lowland forest. Hymenochirus sp. is a new host record for Progonimodiscus colubrifer, having been previously described from Silurana tropicalis. Aplectana mackintoschi is both a new geographical record for Nigeria and a multi-host parasite. We suspect Hyperolius concolor to be a  paratenic rather than a definitive host for the immature Camallanus sp. recovered from the frog. Other parasites using anurans as paratenic hosts were also encountered.Keywords: Anurans, parasites, ecological biotopes, Rivers State, Nigeria

A. P. Ugbomeh

Papers

Parasitic infections of anurans from a freshwater creek community in Delta State, Niger Delta of Nigeria

Anuran parasites from three biotopes in Rivers State, Nigeria