Climate change and sheep parasites


Worm control guidelines have changed since this report, please see SCOPS for latest advice.


Predicted climate change is likely to have profound effects on parasite epidemiology, distribution and prevalence for many parasitic diseases, particularly for those whose free-living stages are sensitive to temperature and humidity. This would challenge the ability for continued control, unless strategies adapt accordingly.

The current reliance on blue-print‘ approaches to parasite control, that are heavily reliant on available chemicals, needs attention, especially as some elements of these strategies are highly selective for the development of parasite resistance.  There needs to be a process of modification and adaptation of newer parasite control strategies.

The increased risk of introduction and potential for establishment of parasitic infections currently considered exotic to the UK, is something that needs to be addressed at the national level, requiring increased surveillance and appropriate instigation of effective intervention control measures.

Predicted climatic changes have a number of potential and consequential effects on sheep husbandry and grazing management. Drought conditions may increase the need for supplementary feeding or the development of drought resistant grazing and in this respect research into bioactive, drought-resistant forages, such as chicory, which can be incorporated into practical production systems, warrants further research.


Planned activity:

Ensuring producers are aware of the final report.  To look at updating their advisory leaflets on parasite control: 8: Target Worm Control for Better Returns and 10: Controlling external parasites for Better Returns to take into account possible effects of climate change on parasite epidemiology, seasonality, available treatments and control strategies are recommended.

Beef & Lamb
Project code:
01 December 2009 - 16 March 2010
AHDB Beef & Lamb
Project leader:
Professor Mike Taylor, FERA

About this project

The Problem:

EBLEX has been involved, through SCOPS, in promoting best practice for external and internal parasite control. However, parasite seasons are changing, for example the traditional season for blowfly strike was also quoted as from May to September, but recent EBLEX advice says that body strike occurs from April to December in the south, and June to November in the north. Understanding what is happening in the external and internal parasite population is very important to be able to advise on prevention and control. This review will also look at prevention and control measures being used in other countries and whether they are applicable here.


Project Aims:

  • To understand how the lifecycles of the major external parasites (sheep scab, blowfly, lice, ticks, keds and headfly) and internal parasites (coccidosis, nematodirus, teladorsagia, haemomchus, fluke, trichostrongylus) are changing with climate change, with reference to the effect on their incidence and prevelance
  • To identify if current prevention and control advice needs to be altered to reflect the change
  • To review prevention and control measures used in other countries



The review will look at future predictions for climate, and use knowledge on temperature- and humidity-dependent sections of the parasites‘ life cycle to suggest what may happen in the future. Incidence figures will be interrogated to see if the increase is due only to climate change.  Information about practices overseas will also be collected.