Browsing by Author "Thiart, Hanlie"
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- ItemConservation implications of avian malaria exposure for African penguins during rehabilitation(Academy of Science of South Africa, 2017-02-15) Botes, Annelise; Thiart, Hanlie; Parsons, Nola J.; Bellstedt, Dirk U.ENGLISH ABSTRACT: The African penguin (Spheniscus demersus) is the only penguin species that breeds on the African continent and it is currently classified as endangered. Its conservation is assisted by the Southern African Foundation for the Conservation of Coastal Birds (SANCCOB) which is a seabird rehabilitation facility based at the Rietvlei Wetland Reserve in Tableview, Cape Town. Despite the success of SANCCOB in rehabilitating diseased, injured or oiled penguins, significant mortalities have occurred at the facility as a result of avian malaria. Avian malaria can be contracted during rehabilitation during which penguins are inadvertently exposed to additional threats. An enzyme-linked immunosorbent assay (ELISA) was used to assess the anti-Plasmodium antibody levels of penguins to avian malaria on entry into the SANCCOB facility from 2001 to 2004 and during their rehabilitation process. Using blood smear data, avian malaria prevalence and malaria-related deaths were also monitored from 2002 to 2013. Significant increases in anti-Plasmodium antibody levels after admission were found during summer months. New infection and not parasite recrudescence was concluded to be the cause of this increase. This source was confirmed by a dramatic drop in penguin mortalities upon exclusion of mosquito vectors in 2008. Mortalities did not depend on the birds’ abilities to produce an anti-Plasmodium antibody response and oiling had no influence on immunity or prevalence of avian malaria infections. This study highlights the importance of mosquito vector control to control pathogen exposure in wild bird rehabilitation centres. Significance: • Efforts to assist with the conservation of endangered species can unintentionally add to the conservation burden. • Rehabilitation influences exposure of African penguins to avian malaria. • Avian malaria prevalence and mortality are not influenced by oiling or anti-Plasmodium antibody responses. • Vector control can limit avian malaria exposure in wild bird rehabilitation centres.
- ItemImmunological and epidemiological investigations into avian malaria in the African penguin during rehabilitation and in breeding colonies(Stellenbosch : University of Stellenbosch, 2005-04) Thiart, Hanlie; Bellstedt, D. U.; University of Stellenbosch. Faculty of Science. Dept. of Biochemistry.ENGLISH ABSTRACT: The African penguin, which occurs along the south-eastern and south-western shores of South-Africa and Namibia, has experienced a severe reduction in population numbers due to guano and egg collection in the first half of the 19th century, and oil pollution in the second half of the 19th century as a result of oil tankers rounding the Cape of Good Hope. The population would have been reduced by a further 19% had it not been for the rehabilitation of penguins at the South African National Council for the Conservation of Coastal Birds (SANCCOB) facility. Although this has been very successful, mortalities as a result of avian malaria infection have considerably reduced the efficiency of rehabilitation. In an effort to assess the role of immunity against malaria in combating the disease, an enzyme-linked immunosorbent assay (ELISA) for the detection of antibody levels to avian malaria was developed. The ELISA was used to detect antibody levels to avian malaria of penguins on entry and during rehabilitation from October 2001 to January 2003. The aim of this study was to continue the determination of antibody levels to avian malaria of penguins entering the SANCCOB facility, in order to allow an evaluation of the antibody levels to avian malaria for two full calendar years. This investigation was combined with a polymerase chain reaction (PCR)-based method, capable of detecting any Plasmodium species in penguin serum. These two methods were also used to investigate avian malaria in several breeding colonies in order to assess the role avian malaria may play in the survival of the African penguin in the wild. Results indicated that the ability of penguins to produce anti-Plasmodium antibodies was not influenced by oiling and that infection with malaria was not due to recrudescence but rather due to infection via mosquitoes. This indicated a possible role of the SANCCOB facility in exposing the penguins to avian malaria. However a large number of penguins arrived at the facility previously infected with malaria, indicating that malaria was present in the breeding colonies. Investigations in the breeding colonies revealed extremely high avian malaria prevalence even though no sick birds or mortalities were observed. This raised the question whether different types of malaria are responsible for infection in the SANCCOB facility and breeding colonies.