INTEGRATED CONTROL OF LIVER FLUKE IN DAIRY CATTLE.

Discipline: disease;

With my regular column of DAIRY R & D IN SA on the website, I from time to time will give feedback on research projects which Milk SA funds. This will deal with progress and plans for the next year or phase. This project by the researchers at UKZN is in its first year of implementation and is envisaged to continue to at least 2019.

Fasciola species are liver flukes that infect cattle and reduce the productivity by 15-30%. The infection can affect feed intake that leads to reduction in milk production and weight gains. Drug control is expensive and resistance is now limiting this option. The proposed alternative is to develop a combination of botanical extracts and bio-control agents to control the different life stages of the liver flukes, and to control the alternate hosts, which are various species of snails. The solution is sustainable, being based on locally sourced botanical extracts to kill adult flukes and on locally sourced bio-control agents to kill the snails. Examples are fungi, bacteria and beneficial nematodes isolated from pastures and water bodies. The main points of the research focus are to:

Screen a range of non-toxic botanical extracts for activity against liver fluke adults and eggs in vitro and in vivo.
Isolate and screen a range of bio-control agents for the control of eggs, metacercariae, miracidia and cercariae, which are the stages that live in pastures even for brief periods before ingestion by snails or livestock.
Isolate and screen bio-control agents for the control of snail species that act as the alternate host in the life cycle of Fasciola species.

Progress up to date (2016):

Plants were collected, dried and grounded into a powder ready to extract
Commencing with extraction of chemical substances
Sourcing of contaminated livers from abattoirs and faecal samples from infected animals
Commencing with development of techniques for maintaining a population of snails as well as to breed them in the large quantities required for a broad screening trial.
Aquatic snails that are prevalent in tropical aquariums and are amenable to producing a large population has been sourced. Cultivation of this species should be relatively easy and offers a source of material for the initial screening of snail antagonists. However, it is time-consuming to multiply the populations and it is anticipated that this will only be ready for assays in 2017 and later.

Research planned for 2017:

- Screen potential botanicals in vitro for activity against Fasciola

- Screen potential bio-control agents against both aquatic and terrestrial snails

- Conduct In vitro and in vivo trials

Reference:

M.D. Laing & M.A. Ahmed, 2016. Integrated Control of Fasciolosis (Liver Flukes) of Cattle. Application for Renewal of Project Proposal for 2017- MILK SOUTH AFRICA; UKZN