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Hexamita & Trichomonas
Hexamita
A motile protozoa otherwise known as ‘Spironucleus’. Found in the caecum and small intestine of pheasants and partridges.
Trichomonas spp.
A family of protozoa that resides in the caeca of many avian species.
Overgrowth of these motile protozoal species will cause disease in birds.
Symptoms
- Depressed with ruffled feathers.
- Weight loss.
- Weakness with eventual death. Mortality can be as high as 80% in birds younger than 10 weeks old.
Diagnostics
- Identification of small oval undulating organisms from fresh intestinal scrapes under microscope.
Treatment
- ‘Emtryl’ was the only treatment available however it is now illegal to be in possession of this drug with intention to administer to game birds.
- Birds lose many electrolytes through the diarrhoea process. Supportive therapy with electrolytes in the water is recommended to increase survival rates.
- Antibiotic therapy has been used to help control this disease however the exact reason for this is under investigation.
Prevention
- Ensure feed and water systems are contained, covered and hygienic.
- Water sanitisation with a suitable product (hydrogen peroxide or chlorine) will reduce the likelihood of shared drinkers being a source of infection for hexamita or trichomonas.
- Acidification of water has also been used with success for prevention and control of these diseases.
- Overstocked pens are more severely affected due to a combination of increased social stress factors and increased incidence of disease exposure. Reduce stocking densities will help to reduce the severity of the disease in the flock.
- Good biosecurity between different groups of birds; change of footwear and separate equipment between houses.
- Rotate house positions/fields per batch of birds.
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Coccidiosis
Coccidia is a protozoal disease. Despite there being many different strains of this protozoa each individual one is very species specific. This means that pheasant coccidia strains will not infect partridges and vice versa.
PHEASANTS
Symptoms
- Strains involved: E. colchici, E.duodenalis, E. megalostoma, E. pacifica, E. phasiani
- Diarrhoea
- Inappetence or anorexia
- Depression, ruffled feathers, hunching
- Poor weight gain
- Dehydration & death
PARTRIDGES
Red Legged partridge are more severely affected than grey partridge.
Symptoms
- Strains involved: E. caucasica, E. procera, E. koifoidi, E. legionensis
- Diarrhoea
- Depression, ruffled feathers, hunching
- Poor weight gain
- Sudden death in red legged partridge
Diagnostics
- Post-mortem: enteritis, watery intestinal contents, caecal cores.
- Microscopy: intestinal scrapes inspected under the microscope to identify coccidial oocysts.
- Faecal oocyst count: oocyst flotation from a pooled sample of faeces.
Treatment
- Anticoccidial treatments:
- Toltrazuril for two days (Baycox, Zorabel)
- Amprolium for seven days (Coccibal, Amproline)
- In severe cases, this may require concurrent antibiotic therapy to settle a bad dysbacteriosis.
Prevention
- Coccidiostats in feed:
- These products help birds to develop natural immunity to coccidia as they age. The drugs restrict coccidia metabolism so that only a low level is maintained in the birds. Therefore immunity is generated more swiftly without the catastrophic damage a clinical outbreak can have on bird growth and wellbeing.
- However, in time the resident population of coccidia on a site will become resistant to the coccidiostat and will no longer have an effect. There is only one licensed coccidiostat drug for game birds, Lasolocid acid (Avatec).
- Rotating paddocks/fields or where housing is placed. Coccidia is a very resilient parasite and will survive for over a year in soil and in housing. Turning the soil can also help.
- Thorough cleaning and disinfection of housing with a product that specifies action against coccidial oocysts (as most products will have no effect):
- Power wash all dirt and dust off equipment and housing.
- Use a detergent to wash the remaining muck off, pay particular attention to gaps and hard to reach places.
- Allow equipment to dry before applying the disinfectant.
- Use a disinfectant to cover all equipment and housing and allow for contact time as advised on bottle, eg. Interkokask or Bi-OO-cyst.
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Blackhead/ Tetra- trichomonas
Blackhead
Blackhead or Histomoniasis is an important disease that affects turkeys, chickens, and game birds such as partridges, pheasants, and quail. The disease is called blackhead after cases in turkeys where infected birds developed a characteristic black head. However, it is very rare to see this symptom. Blackhead is a complex disease caused by the protozoan parasite Histomonas (H.) meleagridis, which are spread to the bird by the caecal roundworm Heterakis (H.) gallinarum.
Symptoms
- Depressed, listless and hunched, with drooping wings and ruffled feathers. It is very rare to see any black or purple colouring of the head.
- Droppings are commonly foamy or frothy and yellow or sulphur-coloured.
- High levels of sudden mortality are common as young birds become sick quickly and usually die within a few days of signs appearing. The disease develops more slowly in older birds and they often become emaciated and may eventually die.
Diagnosis
- The post-mortem signs are very distinct and therefore blackhead can be diagnosed visually.
- Liver and caeca samples may be submitted for histopathology for an official confirmation of protozoa presence.
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Classical blackhead liver lesions.
Treatment
- Historically, the disease was controlled and treated by the administration of dimetridazole (Emtryl) in feed and drinking water. This drug has been withdrawn from use and its use in gamebirds and poultry is now illegal.
- Currently there are no licensed treatments for blackhead in gamebirds or other poultry species.
- All treatments are aimed at preventing secondary bacterial infections.
- In water supplements will help;
- Electrolytes
- Oregano and essential oil based products
- However once mortality has started the prognosis is poor.
- The antibiotic ‘paromomycin’ has been used to prevent the spread of blackhead, but application after infection has not been shown to reduce the number of losses.
Prevention
- Birds are infected when they eat feed, earthworms or droppings that are contaminated with the protozoa or Heterakisworm eggs that contain the protozoa meleagridis. Routine worming is important in preventing blackhead.
- Maintain good biosecurity:
- Protective clothing and changing footwear between groups.
- Utilising covered disinfectant foot dips that are changed regularly.
- Thorough cleaning and disinfection of housing and equipment.
- Ensure the birds are on clean, dry bedding.
Tetratrichomonas
Tetratrichomonas (T.) gallinarum is a protozoan parasite of gamebirds and poultry. It is being seen more frequently in gamebirds, particularly in partridges. Protozoa are very small, single-celled parasites that contribute to a number of diseases in game birds, including coccidiosis, blackhead (Histomoniasis), Hexamita (Spironucleus) and intestinal Trichomonas. Tetratrichomonas is a very similar disease to Blackhead and mixed infections of both protozoa are possible. Tetratrichomonas and blackhead both have similar symptoms, limited treatment options and generally poor outcomes.
Symptoms
- Symptoms are similar to blackhead.
- Depressed, listless and hunched, with drooping wings and ruffled feathers.
- Droppings are commonly foamy or frothy and yellow or sulphur-coloured.
- High levels of sudden mortality are common and may be the only symptom.
Diagnosis
- Tetratrichomonas is usually diagnosed on post-mortem examination.
- Liver and caeca samples for histopathological examination.
Treatment
- Currently there are no licensed treatments for Tetratrichomonas in gamebirds or other poultry species. All treatments are aimed at preventing secondary bacterial infections. However, it is very difficult to prevent high mortality once symptoms have appeared.
- Supportive treatments, such as electrolytes and supplements with essential oils, may reduce mortality and improve outcomes.
Prevention
- As for blackhead.
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Rotavirus
Rotaviruses come in different groups. Group A most commonly cause problems in game birds, but other non-group A virus infections also occurs.
Symptoms
- Affects birds of four to 14 days old.
- Diarrhoea with frothy yellow caecal droppings.
- Secondary bacterial infections from bacteria such as E. coli.
- Mortality in birds when infected in first week of life can be as high as 80%.
Diagnostics
- Post-mortem examination: birds will have frothy yellow caeca, distended intestines and may have liver and heart infections.
- Care must be taken to differentiate between rotavirus, bacterial septicaemias (E. coli) and starve outs in young game birds.
- Rotavirus PCR on faeces (only available for group A). A negative result may not mean you are rotavirus free as a non A group may have been the cause and there is no PCR for these.
- Using a ‘PAGE’ (PolyAcrylamide Gel Electrophoresis) test to identify the group A/nonA Antigens on faeces.
Treatment
- Supportive treatment; keep birds hydrated with electrolytes. Monitor brooding temperature closely to avoid chilling birds.
- Antibiotics may be required to control secondary infections.
- Birds will spontaneously recover if supported through the disease, but may continue to suffer with poor growth throughout life.
Prevention
- Visit sheds in order of age each time, starting with the youngest. This will reduce the likelihood of transferring the virus to the younger more susceptible birds from older stock.
- One possible source of the virus can be direct from hatcheries. Contaminated eggs will infect weak chicks that will then carry and circulate the virus around the other day old poults at placement.
- Thorough cleaning and disinfection between batches of birds.