A molecular method for identifying Calicophoron infecting cattle in South Africa
School of Biological Sciences and Conservation, University of KwaZulu-Natal, Westville, Durban. Email:firstname.lastname@example.org
Calicophoron species were collected from the ruminants of cattle from a Kokstad abattoir in South Africa. The second internal transcribed spacer (ITS-2) of the ribosomal DNA had been used as the genetic marker in this molecular study. In an attempt to identify as well as distinguish Calicophoron, the sequences of the ITS-2 region of various species obtained from the experimental samples were compared to each other and to the sequences of related species obtained from the NCBI Genbank.DNA was isolated from individual flukes collected from six cows, PCR techniques amplified segments of the DNA and allowed for purification and sequencing. Sequence analysis comparisons provided a basis for the phylogenetic tree (neighbour-joining), this indicated that there were two species found, one unnamed and the other C.daubneyi and of the six cows, two were co-infected .B.forskali acted as an intermediate host for the unnamed Calicophoron species, the sequences of four samples were identical to the unnamed Calicophoron species isolated from cercaria of B.forskali. Intestinal paramphistomes are found to be more common in cattle than that of which is indicated by literature, which may be due to difficulty in diagnosis, although sequence comparisons of the ITS-2 regions increased the ability to identify and distinguish Calicophoron.
The disease caused by infestation of ruminants of various hosts with stomach flukes is known as paramphistomosis. The paramphistomidae family consists of various genera, one of which is Calicophoron. This family is characterized by the absence of oral suckers and an acetabulum that is positioned close to the posterior end in adults (Fischoeder, 1901). The disease is known to affect cattle and sheep; some common genera that cause the paramphistomosis include Calicophoron, Cotylophoron,Gigantocotyle, andParamphistomum (Rinaldi et al., 2005). A greater number of species are based solely on their morphology and by connection to their host and geographic distribution. It may be inadequate to rely entirely on morphology to undoubtedly identify species (Nolan and Cribb 2005).
Calicophoron microbothrium is one of the most important causes of paramphistomosis in the African continent (Dinnik, 1964). In the ruminant host, the young parasites initially locate themselves in the small intestine and feed on the lining of the intestine. As they grow, they move from the intestine up to the rumen, where they spend the remainder of their adult lives. Younger worms may cause severe enteritis, mostly in younger calves, as well as dehydration,maldigestion and eventually death may be a result. Hence paramphistomes may be responsible for nutrient conversion, which causes a loss of weight and may decrease the production of milk, which in turn results in economic losses. (Rangel-Ruiz et al., 2003)
These flukes are usually found in small numbers and only significantly affect livestock under conditions such as, heavy infections and in growth stages (Lloyd et al., 2007).Immature paramphistomes may cause death rates as high as80–90% in domesticated ruminants. (Ilha et al., 2005; Khan et al., 2008). “Surprisingly, it seems that the pathogenicity of these flukes in ruminants is still controversial’’(Sanabria and Romero, 2008).There has been little study done on Calicophoron species in South Africa, which makes it relatively harder to make comparisons and analyze data in relation to others.
Ruminant flukes have complex life cycles that most often require an intermediate host for completion of growth, intermediate hosts include planorbid snails, and the cercaria settle on the vegetation cover, where they are eaten by cattle (Lloyd et al., 2007)
Many paramphistomoid worms are...
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