Advances in controlling piglet coccidiosis

The lack of knowledge and understanding of the parasite Cystoisospora suis led to a vicious cycle of uncertainties and unanswered questions at the beginning of research about the disease in the last century. This partially explains the low awareness of the disease amongst veterinarians and for doubts about the primary pathogenicity of the parasite. Since then, intensive research has been conducted, investigating epidemiology, diagnostics, pathomorphological findings, parasite-host relations, economic impact, control measures, drug efficiency and others.

Development in the host and diagnosis

C. suis develops intracellularly in the mucosa of the small intestine of piglets, with young animals in the first 2 to 3 weeks of life being especially susceptible. The infection is initiated following the oral uptake of sporulated oocysts from the environment leading to a complex production of parasitic stages. The entire development lasts only a few days. As a result, oocysts are excreted via the faeces and become infective again after sporulation. Due to the intracellular multiplication of the parasitic stages and consequent damage of the tissue, the host develops severe enteritis, with necrosis and villous atrophy following, displaying non-haemorrhagic diarrhoea. The consequence is disturbed digestive function and lower absorption of nutrients, severely impacting growth. Morbidity within affected litters is high and mortality due to C. suis infections is usually low.

Investigations have shown that piglet coccidiosis occurs worldwide and in all climate zones. Disease awareness varies from country to country, but was extremely low in the past. One reason was that usual procedures used to diagnose parasitic infections were not particularly suitable for the routine identification of C. suis. Therefore, recommendations have been developed for an appropriate faecal sampling (individual samples from a litter being mixed, sampling of several litters, focus on weeks 2 and 3) as well as suitable flotation solutions with higher specific gravity for the identification of oocysts. Even greater sensitivity can be achieved with autofluorescence microscopy, routinely used in specialised laboratories. The development of such diagnostic techniques has evolved as the development of Baycox, the first available toltrazuril for piglets, progressed from the 1980’s until today.

Role of the environment

Whenever C. suis takes the opportunity for rapid multiplication, it adapts to the specific farm conditions until it may ultimately become established as a herd problem. Sows do not play a significant epidemiological role, but overall hygiene has an important impact on the course of infection within a litter. If the immediate environment of piglets is very clean and contamination with oocysts is low, the uptake of oocysts is just a question of chance and time. A first development cycle within piglets with excretion of considerable numbers of oocysts will be necessary in any case to provide a higher infective dose and clinical symptoms following this second infection. Thus, piglets will typically show diarrhoea only from the second week onward. Interestingly or consequently, the disease was named ‘10-day-scour’ in the old days.

If the immediate contamination is already high, the first infection doses are sufficient to produce significant damage in the intestine, thus diarrhoea may start earlier. In addition, another severe consequence may result from a higher contamination in the first days of life: disturbance of the normal gut bacterial colonisation. Early coccidial damage of the mucosa of the small intestine favours a rapid multiplication of mucolytic bacteria like Clostridia. Severe necrotic enteritis may occur as a consequence, even associated with mortalities. These relations have also been studied experimentally.

Eradication of Coccidia is impossible. Thus, control must at least prevent clinical signs and economic losses. As mentioned, contamination of the environment is a significant factor. Therefore cleaning and disinfection of the farrowing pens are important. Oocysts are very resistant to environmental conditions and certain disinfectants; hence only approved disinfectant substances should be used. Concomitantly, the use of single treatment with toltrazuril (Baycox) between day 3 and 5 of life has proven to ensure complete prevention of clinical signs of coccidiosis. It is important that treatments are performed at least on a litter base, following the recommended dose of 20mg of toltrazuril per kilogram of bodyweight.

Figure 1 – Injectable toltrazuril and iron combination reduces oocyst shedding (treatments applied on the same day).

New developments in C. suis control

Piglets are subjected to different management procedures at an early age. Between days 3 to 5 of life, the use of injectable iron preparations to prevent iron deficiency anaemia and an oral dose of Baycox to prevent coccidiosis have become global standards in piglet care. To simplify management, reducing labour for farmers and stress for the piglets, investments in research have been made for over a decade. The first innovation out of this project was the oral combination of toltrazuril and iron, commercialised in selected countries as Baycox Iron Oral. The final outcome of this extensive research is a new, patented formulation containing both toltrazuril and iron in an injectable form. This new development, Baycox Iron Injection, is currently available in Europe. Following positive results published on the oral combination, research has shown the injectable combination to be safe and effective in preventing the oocyst shedding (Figure 1) and clinical signs of coccidiosis, such as diarrhoea and weight loss, as well as iron deficiency anaemia in piglets, ensuring proper health and weight development (Figure 2).

Figure 2 – Weight development in weaning piglets.

The understanding around swine coccidian has immensely progressed over the past several decades. Scientists at Bayer have cooperated with universities, veterinarians and producers to generate and disseminate the majority of information available today about coccidiosis. Years of investment in research have allowed producers to control the severe impacts of the disease, increasing the awareness to the need of higher hygiene standards and providing pharmaceutical solutions that have shaped the way piglets are cared for. Now, as a result of extensive research and knowledge, also the injectable formulation of Baycox Iron is being brought to producers, assisting not only in controlling this important disease, but simplifying piglet management and enhancing piglet well-being.

References available on request

Author: Dr Hans-Christian Mundt, Octavio Orlovsky Eckhardt and Luiz Felipe Lecznieski, Bayer Animal Health, Germany