​Project Manager​: Dr Kerstin Junker

The ARC-OVR currently pursues two main directions in its research on helminth parasites:

  1. Rural livelihoods and anthelmintic control strategies, including technology transfer covering areas such as endoparasite awareness and control, basic hygiene as well as basic animal husbandry and the use of FAMACHA© charts as published in the Goatkeeper’s Animal Health Care Manual.

  2. Helminth taxonomy and biodiversity, including curatorial activities in the National Collection of Animal Helminths.

Rural Livelihoods and Anthelmintic Control Strategies

Gastrointestinal helminths are considered a number one disease impacting on farming systems worldwide. They are a major cause of ill-thrift and production loss in both the commercial and the smallholder farming sector and affect the entire specter of livestock species. Yet, rural development in terms of agricultural development involves increasing the overall productivity and sustainability of farming systems. Sustainable technologies are needed to assist emerging farming communities to contribute to food security and their own economic advancement. Although livestock represent a major asset among smallholders in many developing countries, these herds are seldom, if ever, treated for internal parasites. Resource-poor communities have limited access to facilities, infrastructure, finance and support services. There is thus a need for better accessibility and affordability of information, products as well as services. Helminth control programmes based solely on the use of anthelmintic drugs are no longer considered sustainable because of an increased prevalence of nematode resistance, high costs and concerns regarding residues in the food and environment.

One of the most detrimental helminths to animal health is the roundworm H. contortus, causing severe anaemia and death in goats and sheep. At the same time it is also one of the helminths that have developed pronounced resistance against all major classes of anthelmintics. In collaboration with the Moredun Research Institute, Scotland, an antigen vaccine candidate against H. contortus is currently being investigated. Field trials involving indigenous Boer goats and sheep are conducted at the ARC-OVR to elucidate the immune response and to establish and refine the vaccination schedule and dosage.

  • Epidemiological data on endoparasites in the smallholder farming sector - Dr Ana Tsotetsi

Research in this field is aimed at collecting epidemiological data on endoparasites of cattle and small stock in the smallholder farming sector. It includes surveys on prevalence, intensity of infection and geographic distribution, as well as surveys to assess the prevalence of anthelmintic resistance in the smallholding farming sector.

  • Control strategies against the zoonotic cestodes Taenia saginata and T. solium - Dr Ana Tsotetsi

Man is the sole final host for T. saginata (beef tapeworm) and T. solium (pig tapeworm), while cattle and pigs serve as intermediate hosts. Infection is passed on when human carriers pass faeces containing eggs and these are ingested by the intermediate hosts. Eggs hatch and larvae migrate to the musculature where they develop into cysticerci. Humans are infected primarily when consuming undercooked meat. The presence of adult tapeworms in the intestine usually remains asymptomatic, but exposure to eggs of T. solium through autoinfection or lack of hygiene can lead to neurocysticercosis in humans. Neurocysticercosis can cause epilepsy and is potentially fatal. Especially in less developed countries, the infection of cattle with T. saginata or man and pigs with T. solium causes considerable medical/veterinary and economic problems. Currently bovine and porcine cysticercoses are mainly diagnosed by meat inspection. While this post-mortem examination is useful in detecting cysticercosis in heavily infected carcasses, lightly infected carcasses or dead and degenerated cysticerci are easily missed and passed on for human consumption. Consequently, studies based on the use of meat inspection records tend to underestimate the disease prevalence. The accurate diagnosis of infectious diseases is a prerequisite for the implementation of treatment and control strategies, but the currently available diagnostic tools pose limitations on the timely and correct diagnosis of Taenia infections. More sensitive and specific antemortem tests need to be developed to complement meat inspections.

Presently, a serological assay (antigen detecting ELISA) is used to determine the prevalence and distribution of taeniid infections in cattle and pigs from smallholder farms in the Gauteng and Free State Provinces. In collaboration with the University of Edinburgh, UK, molecular diagnostic tests using PCR are performed to identify/confirm meat inspection results at abattoirs.

Although the above mentioned serological assay has been recorded as being more sensitive than meat inspections and has been successfully used in epidemiological surveys, it is not species specific. Since taeniid species impact differently on human health, with T. solium being one of the most detrimental, an accurate and specific diagnose is imperative. A second project therefore aims to develop diagnostic tools with an improved specificity for bovine and porcine cysticercosis, and is conducted in collaboration with the University of Edinburgh, the Institute Salud Carlos III and the University of the Free State. 

Helminth Taxonomy and Biodiversity

Dr Kerstin Junker; Ms Andrea Spickett

All free-living animals have their own unique parasite assemblages, and parasites in any given system far outnumber their free-living hosts. Parasitic helminths can have a significant impact on host ecology and play an important role in the regulation of host populations. Host response to parasites is energy costly and while endoparasites in themselves might not always be highly pathogenic, they can increase host susceptibility to serious pathogens. Helminths of wildlife might not only pose a threat to their natural hosts but have zoonotic potential as well. Knowledge of the helminth communities of wildlife, their composition and processes that govern their specific patterns is scant, however. This is true not only for South Africa, but for the Afrotropical Realm in general. The diversity of South Africa’s wildlife draws many tourists and the game industry has become a major contributing factor to the country’s economy. In order to assess the possible impact of helminth infections on this valuable resource, helminth biodiversity studies, including the prevalence and geographic range of these parasites in a large variety of vertebrate hosts, are mandatory. Such investigations will provide the baseline data needed to protect and sustainably manage the country’s biodiversity. Creation of extensive data sets will eventually enable us to judge if helminths of wildlife are reservoir hosts for helminths of life stock and vice versa. This is especially critical as human expansion and resulting habitat loss lead to an ever greater livestock/wildlife interphase. Using species composition, species richness, prevalence and intensity of infection as main parasitological descriptors, a number of collaborative studies on the helminth fauna of, not only, South African wildlife are underway. Where possible, an integrated taxonomic approach for the demarcation and characterization of species is being followed, combining detailed morphological descriptions and molecular characterization. Material collected during these studies is used to augment the reference material deposited in the National Collection of Animal Helminths.

Current projects are:

  • Comparative analysis of the gastrointestinal helminth communities of selected taxa of rodents and insectivores in different vegetation zones in South Africa (University of Stellenbosch).

  • Parasite assemblages of Elephantulus myurus and Acomys spinosissimus (University of Pretoria)

  • Pentastomid parasites and gastrointestinal helminths of Crocodylus niloticus (Kruger National Park, South Africa)

  • Pentastomid parasites of Pygocentrus nattereri in Brazil (Universidade Estadual de Maringá, Brasil)

  • Rhabdiasidae in reptilian and anuran hosts (Institute of Zoology, Ukraine)

  • Filarial nematodes and Wolbachia screening (Muséum National d'Histoire Naturelle, France)

  • Taxonomy of spirurid nematodes (Bulgarian Academy of Sciences, Bulgaria)

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