Coccidiosis

A key factor in the productivity of dairy cows is healthy calves, which are the foundation of herd replacement. In the first weeks of calves’ life, diarrhea is the biggest health problem. They can be caused by both non-infectious and infectious factors (bacteria, viruses, parasites). They account above 80% of deaths among calves up to 3 weeks of age. Diseases of the gastrointestinal tract and respiratory system impair weight gain and increase the cost of veterinary care.

Coccidiosis is a disease of the digestive tract caused by protozoa of the genus Eimeria. In cattle, two species of Eimeria bovis and Eimeria zuerni show the greatest virulence. Moreover Eimeria alabamensis – strongly occurring in the pasture period already in the first week of life young calf’s. The incubation period of the disease is 15 to 22 days. Incidence usually occurs between 3 weeks and 6 months of age, with the greatest severity between 2 and 4 months. The disease can also occur in heifers and occasionally in adult animals – being very acute often lethal form. Coccidiosis is one of the main diseases of calves, which can have a devastating effect on the health and condition of animals, causing serious damage to the digestive tract. The disease is characterized by a high degree of infectiousness, so calves with symptoms should be isolated as soon as possible.

The harmfulness of protozoa of the genus Eimeria is largely associated with damage of the intestinal epithelium – mainly enterocytes, as a result, digestibility and absorption of nutrients are impaired. Dehydration, metabolic acidosis and endotoxemia as a result of secondary infections occur. In many cases, the number of oocysts collected is low and the disease is subclinical, and the observed symptoms are not very specific.

Symptoms of clinical coccidiosis include painful diarrhea with pushing, lack of appetite, abdominal pain, presence of blood in faces and/or fever. It should also be noted that in most cases, bovine coccidiosis has a subclinical course, in which diarrhea is not observed or occurs in low intensity. In this form of the disease, there is no destruction of larger areas of intestinal epithelium (as is the case in the acute form) – the epithelium usually regenerates. However, even animals with subclinical coccidiosis are characterized by worse weight gain compared to those not infected. It is very common for most healthy animals to shed oocysts and show no clinical signs. For this reason, determination of the species, as well as counting the oocysts (the size of the infestation), is important for determining an accurate clinical picture.

Factors that favor the occurrence of coccidiosis are related to the environment, the animal and the pathogen. Environmental factors are contaminated litter, equipment, season (humidity, temperature), conditions for oocyst sporulation, hygiene and management. Age (calves from 3 weeks to 6 months), immune decline and susceptibility to infection are important. The pathogenicity of the particular species of coccidia causing the disease, the number of oocysts and mixed infection, and other immunosuppressive factors play a major role. Factors conducive to the occurrence of coccidiosis are also inadequate nutrition (weak calves), deficiency of vitamins (A, K, E), selenium, and contamination of feed with mycotoxins. Also of great importance is the quantity, timing and quality of colostrum, which is a carrier of antibodies, and a large amount of antibodies makes calves less susceptible to infectious agents.

Control of coccidiosis involves reducing the pressure of the pathogen. First of all, it is necessary to ensure appropriate zoohygienic conditions in calf housing, remember to remove manure regularly, buckets and troughs must be cleaned regularly, and bedding should be fresh and dry, which can protect against infection with oocysts, which are found in the feces of sick animals. If possible, keeping calves in groups with a small span of no more than 2 weeks, elevate feeders and drinkers to prevent manure contamination. If diarrhea appears in calves, find out what is causing it using, among other things, rapid field tests based on the immunochromatographic method, and submit fecal samples for laboratory analysis to assess the presence of oocysts. The test, along with species identification, gives a picture of the status of the herd as far as coccidia infestation is concerned and enables appropriate countermeasures to be taken if necessary. Due to the prevalence of non-pathogenic coccidian species in cattle, the detection of oocysts alone without species differentiation is diagnostically of little use. Once coccidiosis is detected in a herd, treatment should be initiated. The timing of initiation of coccidiosis treatment is very important.

Infected animals must be treated for infection and dehydration. Producers should choose the appropriate drugs in consultation with a veterinarian. Sulfonamide drugs and a therapeutic dose of amprolium are available for the treatment of coccidiosis. Antibiotics may be necessary if secondary bacterial infections are suspected.

Feed additives containing immunoglobulins, probiotics and phytobiotics can also play a role in the prevention of coccidiosis.  Plants contain in their composition many types of active substances, i.e. compounds, which have medicinal effects. Due to their content of active substances, herbs are increasingly used as natural immunostimulants. In addition, the use of certain herbs in calf nutrition can help improve palatability and feed intake, resulting in higher weight gains in calves.

Many herbs are known to be effective against parasites. Certain plants have been noted to have beneficial effects against coccidiosis. For example, mugwort (Artemisia annua) reduced intestinal damage caused by oocysts. Another plant with strong antibacterial, antifungal properties and active in controlling Eimeria sp. oocysts is oregano (lembi). The essential oil of oregano contains more than 30 active substances, most of them phenolic, which have a broad spectrum of action. Researchers suggest that oregano essential oil may be effective in the prevention of coccidiosis. Another plant that may find use in the prevention of coccidiosis is Echinacea. Also, common herbal plants may have a supportive effect on coccidiosis. Common nettle, peppermint due to their anti-hemorrhagic effect can reduce the effects of bleeding caused by coccidiosis. In the world, preparations for use in the prevention of coccidiosis based on herbal raw materials have already been developed.
The effectiveness of these composition in the prevention of coccidiosis will be determined by their repeatability and standardization of active substances.