round worms and a protozoa (heterakis gallinarum and histomonas meleagridis)

Discussion in 'Emergencies / Diseases / Injuries and Cures' started by kslamp, Jan 28, 2013.

  1. kslamp

    kslamp Hatching

    Jan 28, 2013
    We recently got two hens. One is laying and seems healthy. The other has had loose stools and isn't laying though she's about nine months old. I took a stool sample to my cat's vet (who doesn't treat chickens) and it came back with round worms and a protozoa--histomonas melegridis. I'm assuming I can treat the worms with wazine/ivermectin. Do I need to treat the protozoa seperately? Does anyone have experience with this?

  2. dawg53

    dawg53 Humble Premium Member

    Nov 27, 2008
    Jacksonville, Florida
    Forget the wazine and ivermectin. You're dealing with the roundworm (cecal worm) that is host for the protozoa that causes blackhead in chickens. Purchase metronidazole online as "fishzole," 250mg tablets. Give your birds one 250mg tablet once a day for 5 days to kill the protozoa. Then purchase either valbazen liquid cattle/sheep wormer or safeguard liquid goat wormer and dose them with either wormer; use a syringe without a needle, 1/2cc orally undiluted. Repeat dosing them again in 10 days. Either wormer will kill the cecal worm. There's a 14 day withdrawal period after last dosing with whichever wormer you decide to use. If your feed store doesnt carry either wormer, you can purchase it from or call them.
  3. kslamp

    kslamp Hatching

    Jan 28, 2013
    Thank you for the post. Once they have the protozoa can they recover? It seems like there is a very high mortality rate from "blackhead".
  4. dawg53

    dawg53 Humble Premium Member

    Nov 27, 2008
    Jacksonville, Florida
  5. kslamp

    kslamp Hatching

    Jan 28, 2013
    One more question about dosing with the wormer. I purchased the Safegaurd (fenbendazole 10%). The packaging lists the dose at .6 ml per 25 lbs. Given my hens are small (one is bantam) that would put the dose at .1 ml. Is that okay? Is there a reason to give a higher dose? I should say, the first dose had some effect--one of the hens passed the largest roundworm I've ever seen.
  6. casportpony

    casportpony Team Tube Feeding Captain & Poop Inspector General Premium Member Project Manager

    Jun 24, 2012
    My Coop
    Poultry are dosed much higher than goats, horse and cattle. My vet told me to dose my birds by mouth at 50mg/kg and repeat in ten days. I have used that dose on chicks, peachicks, turkey poults, quail, turkeys, chickens, ducks, guineas and peafowl.

    10mg ( .1cc) = enough for a 200 gram (7 ounce) bird at 50mg/kg
    25mg (.25cc) = enough for a 500 gram (17 ounce) bird at 50mg/kg
    50mg ( .5cc) = enough for a 1000 gram (35 ounce) bird at 50mg/kg

    50 mg/kg is at the high end of the recommended dose for birds, but it is what my vets recommended.

    From Plumb's Veterinary Drug Handbook - 7th Edition


    Last edited: Feb 18, 2013

  7. casportpony

    casportpony Team Tube Feeding Captain & Poop Inspector General Premium Member Project Manager

    Jun 24, 2012
    My Coop
    From the AAAP Avian Disease Manual

    [FONT=TimesNewRoman,Bold][FONT=TimesNewRoman,Bold]C. HISTOMONIASIS [/FONT][/FONT]

    (Blackhead; Enterohepatitis)
    Histomoniasis is a protozoal disease caused by

    [FONT=TimesNewRoman,Italic][FONT=TimesNewRoman,Italic]Histomonas meleagridis [/FONT][/FONT]affecting turkeys, chickens,
    peafowl, grouse, quail and possibly other gallinaceous birds characterized by necrotizing lesions involving
    the ceca and liver.
    Histomoniasis occurs most frequently in exposed, unmedicated turkeys, especially turkeys under 3
    months of age. It also occurs in chickens and in many captive game birds. Young birds are more
    frequently and severely affected. The disease is infrequent in areas where there are no earthworms i.e.,
    where there is dry, sandy soil and where there are no vectors for transmission of histomonads.
    Histomoniasis occurs infrequently where proper measures are taken for its prevention.
    1. Histomoniasis once limited the expansion of the turkey industry. Prior to development of safe
    antihistomonal drugs, it could be controlled only by cumbersome and relatively ineffective measures
    designed to prevent exposure of turkeys to the embryonated ova of cecal worms (


    2. Significant growth of the turkey industry occurred after safe antihistomonal drugs were developed.
    The disease is now uncommon and these drugs are no longer used routinely. It occurs sporadically
    when turkeys are raised where chickens were previously located. The disease is still common in
    chickens but its effect on production is mild and rarely recognized. Histomoniasis remains an
    important cause of death among other galliformes including peafowl, pheasant and quail.
    1. The etiologic agent is the protozoan

    [FONT=TimesNewRoman,Italic][FONT=TimesNewRoman,Italic]Histomonas meleagridis[/FONT][/FONT], assisted by secondary bacteria. In the
    experimental absence of bacteria, the histomonad appears not to be pathogenic.

    [FONT=TimesNewRoman,Italic][FONT=TimesNewRoman,Italic]H. meleagridis [/FONT][/FONT]is a
    flagellate in the lumen of the cecum but assumes an ameboid form in tissue.
    2. A larger histomonad distinguished by its 4 flagella,

    [FONT=TimesNewRoman,Italic][FONT=TimesNewRoman,Italic]H. wenrichi[/FONT][/FONT], also occurs in the cecum but is not
    Transmission of

    [FONT=TimesNewRoman,Italic][FONT=TimesNewRoman,Italic]H. meleagridis [/FONT][/FONT]to susceptible birds is possible via three routes:
    1. Ingestion of fresh feces. This route probably is relatively unimportant except for spread within a flock.
    2. Ingestion of embryonated cecal worm ova containing the protozoan. Within these resistant ova the
    histomonad can survive for years.

    [FONT=TimesNewRoman,Italic][FONT=TimesNewRoman,Italic]H. meleagridis [/FONT][/FONT]is liberated in the intestine when ingested ova hatch,
    then invades the cecal wall and initiates the disease.
    3. Ingestion of earthworms containing cecal worm larvae within their tissues. Earthworms serve as
    transport hosts for the cecal worm and the cecal worm acts as a transport host for the histomonad.
    Infection results after the cecal worm larvae are liberated during digestion.
    1. Diagnosis can be made on the basis of clinical signs and characteristic lesion. Typical well-developed
    lesions are pathognomonic [

    Fig. 1; Histomoniasis; NCSU].
    2. In turkeys histomoniasis appears 7-12 days after exposure. Initially there is listlessness, moderate
    anorexia, drooping wings and yellow ("sulfur colored") feces. Head parts may be cyanotic
    ("blackhead") although they often are not. In chickens with histomoniasis there may be some blood in
    the feces.
    3. Later the affected turkey is depressed and stands with its wings drooping, eyes closed, head drawn
    close to the body. Emaciation is common in chronic cases, usually in older birds. In young turkeys
    morbidity and mortality are high, up to 100%. Older birds tend to be more resistant.
    4. Gross lesions. Bilateral enlargement of the ceca with thickening of the cecal walls [

    Fig. 2;
    Histomoniasis; UC Davis

    ]. The mucosa usually is ulcerated. The ceca often contain caseous cores
    which are yellow, gray or green and may be laminated. In chronic cases the cores may have been
    expelled. Peritonitis occurs when the cecal wall becomes perforated.
    5. Liver contains irregularly-round, depressed, target-like lesions that vary in color [

    Fig. 3;
    Histomoniasis; UC Davis

    ]. They often are yellow to gray but may be green or red. They vary greatly
    in diameter but often are 1-2 cm and may coalesce to produce larger lesions.
    6. Lesions may not be entirely typical in birds under treatment, less susceptible avian species or young
    turkeys in the early stages of the disease. In most infected flocks typical lesions usually can be found
    if an adequate number of birds are examined. In quail, cecal lesions may not occur even though
    mortality is high.
    7. Microscopically, histomonads can be found in the inflamed cecal walls and necrotic foci which
    develop in the liver. In birds killed for necropsy the agent sometimes can be identified in smears from
    the ceca or in scrapings from the margin of hepatic lesions.
    1. Histomoniasis usually can be prevented by adding antihistomonal drugs to the ration in proper dosage.
    No current preventive medication is approved in the U.S. Histostat (nitarsone) is still used in poultry
    outside the U.S. In quail, a cholinesterase inhibiting carbamate (Sevin) increases susceptibility to
    2. Control by the use of antihistomonal drugs may fail unless reasonably good sanitation is practiced.
    3. Other measures that assist in control follow:
    A. Do not keep chickens and turkeys (or other susceptible birds) on the same farm.
    B. Do not use chicken ranges for turkeys or other susceptible birds unless those ranges have been
    free of chickens for at least 4 years.

    [FONT=TimesNewRoman,Italic][FONT=TimesNewRoman,Italic]H. meleagridis is quickly destroyed by disinfectants and drying unless protected within
    earthworms or within the cecal worm ova. Avoid exposure to vectors. If possible, raise
    susceptible birds on sandy, dry, loose soil. Prevent access to earthworms after rains. In range
    birds, rotate ranges periodically if possible. Some operators with small lots replace the top
    few inches of soil every few years using power equipment or plow the lots to reduce the
    number of cecal worm ova and other pathogens.
    D. Reduce access of birds to their own droppings or to feed and water contaminated with
    droppings. Place feeders and waterers on large wire platforms or keep them outside of the lot
    but accessible through a wire fence.

    There is currently no approved medication for treatment of histomoniasis in food animals. Small
    groups of birds not being raised for consumption can be effectively treated individually with metronidazole
    at a dose of 30 mg/kg orally SID for 5 days. Antihelmentic treatment may help suppress the population of
    cecal worms.

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