Best Ways to Prevent and Control Coccidiosis among Poultry Birds

Best Ways to Prevent and Control Coccidiosis among Poultry Birds

Introduction

Coccidiosis is the major parasitic disease of poultry with extensive financial losses to the farmer is not properly taken care of and as at when due.

In the past, it has been discovered that the eradication of coccidia can be achieved through practical and hygienic measures which can be able to save your birds from infections while today, the prevention and control of coccidiosis is based totally on chemotherapy, the use of anticoccidial drugs and/or vaccines together with hygienic measures and continous farm control.

Meanwhile, the performance of the anticoccidial agents may be reduced by means of drug resistance and management programs.

As at date, numerous specific live vaccines has been commercially developed in order to assist farmers in fighting coccidiosis on their farms to avoid huge loses.

Aetiology

Coccidia are protozoa which have the ability to multiply rapidly inside cells lining the intestine or caeca. The species of coccidia that are infective to poultry belong to the Eimeria genus.

Many of these species can infect poultry and there is no cross-immunity between them. Most infestations under field conditions are mixed but one species will be dominant. Eimeria have a self-limiting life cycle and are characterized by a high tissue and host specificity.

The Eimeria cycle includes two distinct phases which includes;

(a) the internal phase (schizogony + gamogony) in which the parasite multiplies in different parts of the intestinal tract and the oocysts are excreted in the faeces (The part of the intestinal tract and the total duration of the internal phase of the cycle is dependant on species),

(b) the external phase (sporogony) during which the oocyst must undergo a final process called sporulation before they are again infective. Sporulation requires warmth (25–30˚C), moisture and oxygen (Levine, 1982).

Seven species of Eimeria are known to infect chickens and they show a wide variation in their pathogenicity (Table 1). In addition, two further species have been described, namely E. hagani and E. mivati, but further studies on the importance of these species are needed (Conway and McKenzie, 2007).

Table 1. Some characteristics of important Eimeria spp. infecting chickens

Einige Merkmale der wichtigsten Eimeria spp. bei Hühnern

Host Eimeria Location Pathogenicity*
Chickens E. acervulina Duodenum, Jejunum ++
E. brunetti Ileum, Rectum +++
E. maxima Duodenum, Jejunum, Ileum ++
E. mitis Duodenum, Jejunum +
E. necatrix Jejunum, Caeca +++
E. praecox Duodenum, Jejunum +
E. tenella Caeca +++
* – non-pathogenic; + low pathogenic; ++ moderately pathogenic; +++ highly pathogenic

In turkeys seven species of Eimeria have been reported (Table 2), however E. innocua and E subrotunda are considered non-pathogenic (Trees, 1990; McDougald, 2003).

Table 2. Some characteristics of important Eimeria spp. infecting turkeys

Einige Merkmale der wichtigsten Eimeria spp. bei Puten

Host Eimeria Location Pathogenicity
Turkeys E. adenoeides Caecum +++
E. dispersa Duodenum, Jejunum +
E. gallopavonis Rectum ++
E. innocua Duodenum, Jejunum
E. meleagridis Caecum +
E. meleagrimitis Duodenum, Jejunum +++
E. subrotunda Duodenum, Jejunum
* – non-pathogenic; + low pathogenic; ++ moderately pathogenic; +++ highly pathogenic

Geese are parasitized by two species; Eimeria truncata (unusually this is found in the kidney) and Eimeria anseris. A large number of specific coccidia have been also reported in ducks, but the validity of some of them is still not clear. The most pathogenic coccidial infection of ducks is Tyzzeria perniciosa, which causes haemorrhagic enteritis in ducklings less than 7 weeks of age (Trees, 1990; McDougald, 2003).

Best Ways to Prevent and Control Coccidiosis among Poultry Birds
Birds affected with Coccidiosis

Method of Transmission

The oocysts are extraordinary resistant to environmental stress and disinfectants, remaining viable in the litter for many months. Temperatures above 56˚C and below 0˚C are lethal but it seems to be impossible to decontaminate a previously contaminated poultry house or environment. Sporulated oocysts can be spread mechanically by wild birds, insects or rodents and via contaminated boots, clothing, equipment or dust. Direct oral transmission is the natural route of infection (McDougald, 2003).

Clinical signs and lesions

Several Eimeria species are able to cause clinical signs in infected and unprotected birds; however subclinical infections are frequently seen. These are often underestimated but mostly result in impaired feed conversion and reduced weight gain.

Coccidiosis generally occurs more frequently during the warmer months of the year (Smith, 1995). Young birds are more susceptible and more readily display signs of disease, whereas older chickens are relatively resistant as a result of prior infection.

The severity of an infection depends on; the age of birds, Eimeria species, number of sporulated oocysts ingested, immune status of the flock and environmental management.

Infected birds tend to huddle together, have ruffled feathers and show signs of depression. The birds consume less feed and water, and droppings are watery to whitish or bloody. This results in dehydration and poor weight gain as well as mortalities.

The lesions of coccidiosis depend on the degree of inflammation and damage to the intestinal tract. They include thickness of the intestinal wall, mucoid to blood-tinged exudates, petechial haemorrhages, necrosis, haemorrhagic enteritis and mucous profuse bleeding in the caeca.

The tissue damage in the intestinal tract may allow secondary colonization by various bacteria, such as Clostridium perfringens (Helmbolt and Bryant, 1971), or Salmonella Typhimurium (Arakawa et al., 1981; Baba et al., 1982). Infestation with E. tenella also increases the severity of Histomonas meleagridis infection in chickens (McDougald and Hu, 2001).

Diagnosis

Coccidiosis is often extremely difficult to diagnose and can only be done in the laboratory (Conway and McKenzie, 2007), by counting coccidia per gram of faeces and/or examining the intestinal tract to determine the lesion scores, as described by Johnson and Reid (1970). The estimation of the lesion scores is difficult in turkeys (Irion, 1999). Since it is common for healthy birds to possess some coccidia, consideration of flock history and lesion scores must be carefully evaluated before making a diagnosis or treatment recommendations.

Intestinal coccidiosis may be confused with necrotic enteritis, haemorrhagic enteritis, or other enteric diseases. Caecal coccidiosis may be confused with histomoniasis and salmonellosis due to their similar lesions (Hafez, 1997).

Related posts

Leave a Comment