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 hasbeen discovered that the eradication of coccidia can be achievedthrough practical and hygienic measures which can be able to saveyour birds from infections while today, the prevention and control ofcoccidiosis is based totally on chemotherapy, the use ofanticoccidial drugs and/or vaccines together with hygienic measuresand continous farm control.

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

As at date, numerousspecific live vaccines has been commercially developed in order toassist farmers in fighting coccidiosis on their farms to avoid hugeloses.

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 ofEimeria are known to infect chickensand 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 thesespecies are needed (Conwayand McKenzie, 2007).

Table1. Some characteristics of important Eimeria spp. infecting chickens

Einige Merkmale derwichtigsten 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 turkeysseven species of Eimeria have been reported (Table 2),however E. innocua and E subrotunda are considered non-pathogenic(Trees,1990; McDougald,2003).

Table2. Some characteristics of important Eimeria spp. infecting turkeys

Einige Merkmale derwichtigsten 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

Methodof Transmission

The oocysts areextraordinary resistant to environmental stress and disinfectants,remaining viable in the litter for many months. Temperatures above56˚C and below 0˚C are lethal but it seems to be impossible todecontaminate a previously contaminated poultry house or environment.Sporulated oocysts can be spread mechanically by wild birds, insectsor rodents and via contaminated boots, clothing, equipment or dust.Direct oral transmission is the natural route of infection(McDougald,2003).

Clinicalsigns and lesions

Several Eimeriaspecies are able to cause clinical signs in infected and unprotectedbirds; however subclinical infections are frequently seen. These areoften underestimated but mostly result in impaired feed conversionand reduced weight gain.

Coccidiosis generallyoccurs more frequently during the warmer months of the year (Smith,1995). Young birds are more susceptible and more readily displaysigns of disease, whereas older chickens are relatively resistant asa result of prior infection.

The severity of aninfection depends on; the age of birds, Eimeria species, number ofsporulated oocysts ingested, immune status of the flock andenvironmental management.

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

The lesions ofcoccidiosis depend on the degree of inflammation and damage to theintestinal 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 inthe intestinal tract may allow secondary colonization by variousbacteria, such as Clostridium perfringens (Helmboltand Bryant, 1971), or Salmonella Typhimurium (Arakawaet al., 1981; Babaet al., 1982). Infestation with E. tenella also increases theseverity of Histomonas meleagridis infection in chickens (McDougaldand Hu, 2001).

Diagnosis

Coccidiosis is oftenextremely difficult to diagnose and can only be done in thelaboratory (Conwayand McKenzie, 2007), by counting coccidia per gram of faecesand/or examining the intestinal tract to determine the lesion scores,as described by Johnsonand Reid (1970). The estimation of the lesion scores is difficultin turkeys (Irion,1999). Since it is common for healthy birds to possess somecoccidia, consideration of flock history and lesion scores must becarefully evaluated before making a diagnosis or treatmentrecommendations.

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

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