Cooperia: the not so placid parasite - Veterinary Practice
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InFocus

Cooperia: the not so placid parasite

DEBBIE DOYLE reviews the impact of a parasite which has become the most prevalent parasite of cattle in the US and which is becoming increasingly prevalent in the UK

COOPERIA has generally been considered a relatively mild pathogen of the gastrointestinal tract of cattle.

It is known to be a major component of parasitic gastroenteritis (PGE), exacerbating disease caused primarily by Ostertagia and Haemonchus, and being the main contributor to faecal egg counts, but relatively little work has been done looking at its impact on production.

In the past few years Cooperia has been identified as the most prevalent parasite of cattle in the US 1 and increasingly so in the UK. Not only has its prevalence changed but new studies are revealing the “hidden losses” to production caused by Cooperia infections.

As a result it is important to reconsider the significance of this particular parasite and the potential benefits of ensuring its control in routine worming programmes.

Life story

Cooperia oncophora is the commonest species found in the UK, C. punctata, C. pectinata and C. surnbada can also infect cattle but are less prevalent.

C. oncophora is commonly found in young cattle in their first grazing season. Although immunity rapidly develops by the end of the season, damage can be done in a relatively short time.

The parasite has a direct life-cycle: eggs are shed onto the pasture, grazing cattle ingest infective larvae, which remain in the small intestine whilst they develop into adults. C. punctata and C. pectinata are thought to cause more of a problem because developing larvae burrow into the intestinal mucosa whilst C. oncophora remains on the surface.

The pre-patent period is only 15 to 18 days. Some larvae will undergo hypobiosis and re-emerge after winter. Larvae can also survive over winter on pasture. In addition, some individual cows fail to develop immunity and continuously shed eggs. These small numbers of individuals are thought to be responsible for the majority of pasture contamination.

According to the Veterinary Laboratories Agency, Cooperia used to be found in 40% of grazing cattle samples, but this prevalence had already increased to 70-90% by 2008.2

Pathology and clinical signs

The parasite causes stunting of intestinal villi, significant reductions in nutrient digestion and absorption, leaking of protein into the gut lumen and excess mucus secretion.

Clinical disease is relatively mild or absent and can include diarrhoea, loss of appetite, reduced weight gain and even submandibular oedema from excess protein loss.

Production losses

The true cost of Cooperia infections has not been well studied, apart from two fairly old experimental studies. In 1979 a study found that heavy burdens of Cooperia reduced liveweight gain by 13.5% in a group of four-and-a-half month old calves fed ad lib.3

Then in 1987 another study reported that weight gain in infected growing calves was reduced by as much as 9kg over a 10-week period.4

More recently a paper was published from the US looking at the effects of artificial infection of C. punctata on 200 yearling calves over a two-month period.1 All calves were vaccinated and dewormed upon arrival at the feedlot.

They were allowed to mingle for a month before being randomly selected into two groups. One group were controls, the other received two Cooperia inoculations, 14 days apart (day 0 and day 14). All calves were fed the same standard growing ration.

Egg counts were positive 14 days after the first inoculation and remained at numbers similar to values seen in field studies. After 60 days the control group had gained weight 7.5% more rapidly (p=0.02) than infected calves, 1.47kg per day versus 1.36kg per day respectively.

The Cooperia infected calves also consumed 0.68kg per day less dry food than controls (p=0.02). The results suggested that Cooperia reduces both appetite and nutrient uptake or utilisation, which can result in significant production losses such as liveweight gain.

Control

Not all wormers are licensed against Cooperia and those that are vary in their durations of action. Currently doramectin (Dectomax, Elanco Animal Health) has the longest licensed duration of action against Cooperia: 21 days with the 10mg/ml solution for injection for cattle and sheep, whilst the pour-on 5mg/ml formulation is licensed for 28 days activity.5

The zero and eight week strategic control programme recommended for PGE using doramectin will also control Cooperia.

Worming at turnout (week zero) should reduce new contamination of pasture. Calves will still have low level exposure to over-wintered larvae on the pasture, allowing immunity to develop.

A second dose at eight weeks will prevent large Cooperia burdens building up in the cattle, whilst also reducing egg shedding and avoiding a peak of egg numbers on the grass in June/July.

Summary

Evidence suggests that not only is Cooperia becoming highly prevalent in the UK, but it can cause significant production losses. Therefore using a wormer that has long lasting action against Cooperia in strategic worming programmes (designed to prevent PGE and lungworm) can have extra benefits in terms of overall production.

References

  1. Stromberg, B. E. et al (2012) Cooperia punctate: effect on cattle productivity? Vet Parsitol 183 (3-4): 284-291.
  2. Action on Animal Health and Welfare. Defra and ADAS Jan/Feb 2008.
  3. Coop, R. L., Sykes, A. R. and Angus, K. W. (1979) The pathogenicity of daily intakes of Cooperia oncophora larvae in growing calves. Vet Parasitol 5: 261-269.
  4. Armour, J. et al (1987) Pathophysiological and parasitological studies on Cooperia oncophora infections in calves. Res Vet Sci 42 (3): 373-381.
  5. Dectomax: Elanco Animal Health data sheets, NOAH Compendium 2013.

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