Dear fellows,
I may not be available until next January due to final semester 5 exam.
Most of my time will be spent on tests, books and practicals
Wish me good luck!
Final Exam Semester 5
1-14 January 2012
Haemonchosis (Barber's pole worm) infestation
The haemonchosis infestation came out in pathology test today! It reminds me of Veterinary Institute of Malaysia, a year ago doing my voluntary practice in ruminant. We came across this case.
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Haemonchos contortus
Haemonchus contortus, also known as red stomach worm, wire worm or Barber's pole worm, is very common parasite and one the most pathogenic nematode of ruminants. H. contortus is a highly pathogenic parasitic nematode of that can infect a large number of wild and domesticated ruminant species and is the most economically important parasite of sheep and goats worldwide. Although originally a tropical parasite, it has been disseminated around the world by livestock movement and can now be found as far north as the arctic circle.
Adult worms are blood feeders that reside in the abomasum (stomach) and are approximately 2cm in length when mature. They are dioecious with single females typically producing several thousand eggs per day which pass out of the host in faeces and develop to infective larvae on the pasture.
H.contortus on the abomasal surface of the infected sheep
Anemia, low packed cell volume (PCV), diarrhea, dehydration,peripheral, and internal fluid accumulation are common signs of barber pole worm infestation. Infested goats have lower growth rates, markedly reduced reproductive performance, and have higher rates of illness and death. Consequently, H.contortus may account for greatly reduced profits in a goat operation.
Fluid accumulation at the submandibular region (bottle jaw)
Life cycle of H.contortus
Goats are born without H. contortus; however,they become infested with the worm when theystart grazing. The L3, or infecting larvae, are eatenby the goats during grazing. The L3 larvae thenburrow into the internal layer of the goat's abomasums (true stomach) where they develop to a L4, or pre–adult larvae. The L4 molts into L5, the adult form.
Adult male and female worms live in the abomasum of goats, where they feed on blood. The worms mate and produce eggs. Adult females deposit from 5,000 to 10,000 eggs per day, whichare passed through goat feces to the pasture. Eggsare hatched either in soil or water. When the soil iswarm and moist, eggs will hatch into L1 larvae(first stage juveniles). The L1 larvae then develop through stages L2 and L3. Large numbers of juvenileparasite worm (L3) may accumulate on heavily grazed pastures.
Life cycle of H.contortus
Factors that predispose animal to haemonchosis
- Environment with high temperatures,humidity, and rainfall
- Genetic make-up of goats makes them highly susceptible
- Resistance to anthelmintics as a resultof excessive usage
- Frequent anthelmintic treatments per year without a positive fecal sampleexam
- Many goat producers overstock their pastures and maintain as many as 40 goats per acre
- Few anthelmintics drugs are approvedby the Food and Drug Administrationfor goat use.
Damage cause by the worm
After a goat has ingested L3 larvae, the worm will burrow into the mucosal(internal layer) of the stomach,nourishing on the red blood cells of the goats, which can be life-threatening to the goat. An infected goat can bleed to death within hours.
The resulting blood loss causes the goat to become anemic, with pale mucous membranes. In addition to bottle jaw, goat owners may notice diarrhea, dehydration, lethargy and overall sickly appearance. Left untreated, the goat can die from blood loss, especially younger goats.
Bottle jaw is used to describe the accumulation of fluid (edema) within the tissues under the jaw. It is described as pitting edema, because finger pressure into the tissues creates a pit that only slowly resolves. Parasites withing the intestinal tract consumed such a large amount if protein that the animal is unable to maintain normal protein within the blood to freely move to the extracellular fluid. The walls of the capillaries act as a semipermeable membrane, that do not allow freely move to the extracelluar fluid. Water on the other hand, is able to move freely in either direction. Osmosis occurs across the wall of the capillaries. Within normal blood protein levels, a balance is reached between the extracellular fluid and the liquid portion of the blood.
As protein level levels decline, there is less osmotic pressure within the blood vessels. As protein continue to decline, water accumulates within the tissues. In animals with severe parasitism, the most common site for this fluid accumulation occur is below the jaw due to gravitational force.
Clinical signs of barber's pole infestation
- Diarrhea
- Dehydration
- Unthrift appearance, rough hair coat, depresssed, low energy,lethargic, and uncoordinated• Significantly reduced growth and reproductive performance
- Fluid accumulation in sub-mandibular tissues (bottle jaw),abdomen, thoracic cavity, and gut wall
- Blood loss, white mucous membranes, anemia/PCV
Treatment and Control
Anthelmintics (chemicals/drugs) are widely used to battle barber pole worms. However, only two anthelmintics are approved by the Food and Drug administration; Morantel tartrate and fenbendazole. Anthelmintics are widely used to battle worms and worm eggs.
The key to parasite control is to break the life cycle of the parasite. This is accomplished through good management practices and deworming at strategic intervals. Some of the more common deworming strategies are: Pre-lambing treatment, prophylactic treatment in the spring, and the treat-and -move strategy. Each of these strategies has different guidelines and goals.
Meducci's note: Fecal egg count is considered to be conducted every 6 months to determine the effectiveness of the anthelmintics used.
Overuse of anthelmintics has resulted in increasingly drug-resistant worms. Prevention is much easier than treating the goat once bottle jaw develops. Ideally, pastures should not have been grazed by goats or sheep for at least six months. Pastures in which cattle or horses have grazed are a better choice.
Deworming the sheep
Other good pasture management includes fields which have been rotated with row crops or newly planted or renovated fields.If possible, plant a variety of shrubs and forages for goats to feed on. They prefer this to grass, and plants over 6 inches tall minimize the risk of grazing on contaminated grass. If shrubs are not an option, planting clover, vetches and chicory can be planted. These plants contain condensed tannins which reduce the number of stomach worms and egg production.
Also consider supplementing the goat’s diet with sericea lespedeza hay, which can reduce fecal egg count by 80%.Finally, keeping a healthy herd can help minimize the risk of bottle jaw. Keep healthy goats and cull out sick goats so they do not spread the worms. Do not put more goats on an area of pasture than it can support. Provide clean, fresh drinking water. Use hay racks to keep hay off the ground and away from feces. Check goats frequently for early signs of infection, such as paler than normal gums and eyelids.
Sources: Introduction of veterinary science; James B. Lawhead, MeeCee Baker, H.contortus wikipedia.org, H.contortus; www.sanger.ac.uk, Bottle jaw in goats; causes and treatment, www.helium.com, H.contortos (Barber;s pole worm) infestation in goats, Alabama A&M and Auburn University.
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