Lungworm disease in ruminants-Cause and control.pptx

Lungworm is a important internal parasite found in ruminants. It is caused due to feeding on the lungworm infected pasture land.

1. Lungworm disease in Cattles Submitted by, Varsha

2. Introduction Also called as Husk (Britain), Hoose (Ireland), Parasitic Bronchitis or Verminous bronchitis. Infection of lower respiratory tract. Caused by several parasitic nematodes. Usually results in bronchitis and pneumonia. Infects wide host range including cattle, sheep, goat and pig etc.

3. Etiology The lungworms include several species in the genus Dictyocaulus which infest hoofed animals. Different species are found in cattle ( Dictyocaulus viviparus ), Donkey and Horses( Dictyocaulus arnfeldi ) and Sheep and goats ( Dictyocaulus filaria, Protostrongylus rufescens and Mullerius capillaris)

4. Disease cycle This parasite has a direct life cycle, so infection merely requires management factors that allow a build up of the parasite Adult lungworms reside in the trachea and bronchi. Eggs produced by female adults hatch either in the trachea or before being passed in the faeces. The progression to the infective third stage larvae requires only 5 days. The larvae are then ingested during consumption of contaminated grass in a pasture. Ingested larvae traverse the intestinal wall to reside in lymph nodes, moult to the fourth stage, and within 1 week migrate to the lungs through lymphatic or blood vessels. The final fifth stage is reached after the larvae arrive in the bronchioles.

5. Disease cycle

6. Clinical signs of the disease Varying degrees of dyspnoea , a characteristic deep and moist cough, and moist rales or crackles heard over the entire lung. Coughing is more severe and prominent. Diffuse rales are an important sign that differentiates lungworm from bacterial pneumonias. Severely affected calves or cows will show “heave”-like breathing with visible expiratory and Inspiratory effort. In some cases, emphysema is present when heavy airway exudate results in extreme mechanical respiratory efforts.

7. Clinical signs of the disease Fever (103.0° to 106.0°F) may be present because of secondary infection by bacteria. Affected cattle continue to eat unless severe dyspnoea or coughing interferes with their ability to ingest feed.
In cases with severe dyspnoea, frequent coughing, open-mouth breathing are noted. Usually several animals in a group or the entire herd will show signs.
The reinfection syndrome is characterized by clinical sign of severe coughing in the majority of cattle after their introduction to infected pastures.

8. Pathogenesis Larvae migrating through the alveoli and bronchioles produce an inflammatory response, which may block small bronchi and bronchioles. The bronchi contain fluids and immature worms; Secondary bacterial pneumonia and concurrent viral infection may occur.
Inflammatory process spreads to the surrounding per bronchial tissue and exudates pass back in to the bronchioles and alveoli causing atelectasis and catarrh or pneumonia. The young larvae passing through the intestine cause the diarrhoea.

9. Stages of the infection 1. The Penetration Phase (days 1-7 p.i .) during which larvae penetrate into the body o f the host and migrate to the lungs. 2. The Prepatent Phase (days 8-25 p.i .) during which larvae develop in the lungs. 3. The Patent Phase (days 26-60 p.i .) when the worms are mature and egg-producing. 4. The Post-Patent Phase (days 61-90 p.i .) which is normally the recovery phase after the adult worms have been expelled. (p.i. – post infection)

10. Diagnosis Diagnosis is based on history, clinical sign, epidemiology, presence of first stage larvae in faeces, and necropsy of animals in some herd or flock. The main parasitological method of confirming lungworm disease is by detecting the L1 stage in faecal samples using the Baermann technique. A convenient method for recovering of larvae is in the vermin technique in which faeces (25kg) are wrapped in cheese cloth and suspend or place in water container in conical flask. The water at the bottom of flask is examined for the larvae after four hours, in heavy infection; may be present in 30 minutes.

11. Treatment Treatment of primary D. viviparus infection consists of an anthelmintic to destroy the parasite and whenever necessary, antibiotic therapy to control secondary bacterial infection of the lower airway. Levamisole phosphate (8 mg/kg body weight, SC or orally), fenbendazole (5 mg/kg orally), albendazole (10 mg/kg orally), and ivermectin (0.2 mg/kg SC) all have been recommended as treatments for primary D. viviparus infection in the past. Moxidectin (0.5 mg/kg) and eprinomectin (1 mL/10 kg) as pour-on preparations should also be effective. The secondary bacterial invader is P. multocida, cattle with bacterial bronchopneumonia may be treated with tetracycline, ceftiofur, ampicillin, or penicillin.

12. Residual activities of macrocyclic lactones Active Route Protection (days) Doramectin Injection 35 Pour-on 42 Eprinomectin Pour-on <28 Ivermectin Injection <28 Pour-on <28 Injection 1% 42 Moxidectin Injection 1 % 120 Pour-on 42

13. Prevention and control As there is no any effective treatment for control of the disease, prophylaxis and control of the disease is important. Precaution should be taken to avoid the introduction of “carriers” into herds free of the infection. Examination of all the new cattle before introduction to the existing herd. Animals should not be allowed to graze in the infected pasture lands In cases of outbreaks, animals must be removed from infected pastures, paddocks or barn-yards, given nourishing food and properly housed.

14. Prevention and control Coughing animals should be isolated away from healthy stock. On farms where infection exists, proper drainage of pastures should be undertaken, especially of low-lying areas. Sterilization of pastures can be achieved by leaving fields unoccupied by cattle for a time. Before being pastured, yearling heifers should be treated with anthelmintic effective against D. viviparus , and all animals should be treated routinely with anthelmintic at monthly intervals if the animals are to be placed on contaminated pastures

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