In India, outbreaks of pulmonary fasciolosis due to Fasciola gigantica in sheep have been reported from Uttar Pradesh (Katiyar and Tewari, 1982), Jammu and Kashmir (Pandit et al, 1991) and Andhra Pradesh (Bhaskara Rao and Madhubala, 1998). Infection with Dictyocaulus filarial among sheep was reported by Bhatia and Pande (1960) in Uttar Pradesh and by Dhar et al. (1972) from Kashmir. This communication deals with an outbreak of mixed infection of F. gigantica and D. filarial in lungs of Nilagiri sheep at Nilgiris hills, Tamil Nadu.

Investigation was taken up to find out the cause of sudden death of 8 Nilagiri sheep in a flock of 151 at Karinmuli mund, Nilgiris district, Tamil Nadu between December 1998 and May 1999. Post-mortem examination was conducted on all 8 sheep that died during the period and relevant material was collected for examination (Soulsby, 1982).

On post-mortem examination, lungs were found inflammed with necrotic areas over left border and left apical lobe. Necrosed areas were swollen. Immature flukes were recovered from necrosed area while adult round worms were recovered from the bronchi, bronchioles and alveoli. Recovered flukes and round worms were identified as immature F. gigantica and adult D. filarial respectively.

On post-mortem, liver was enlarged, haemorrhagic and friable and immature flukes were recovered from haemorrhagic tract and also in liver parenchyma. The gall bladder was distended with adult flukes. The flock was originally identified from an outbreak area for fascioliosis in liver due to F. gigantica (Soundararajan et al., 2000).

The overall mortality was 5.3% (8/151). Out of 8 dead animals, 4 (50%) died due to immature F. gigantica in lungs. Two animals (25%) died due to mixed infection with immature F. gigantica and adult D. filaria in lungs. All the dead animals had immature F. gigantica in liver also and one animal had adult F. gigantica in gall bladder. This is in concurrence with that of Pandit et al. (1991) and Bhaskara Rao and Madhubala (1998) who reported isolated cases of Fasciola sp. infection with involvement of lung parenchyma. Dhar et al. (1972) reported D. filaria in lungs of sheep in Kashmir.

The number of immature F. gigantica and adult D. filaria recovered from lungs varied from 6–22 and 11–32, respectively while the number of flukes recovered from liver and gall bladder ranged from 42–52 and 3, respectively. The present paper represents a typical case of mixed infection of F. gigantica and D. filarial in lungs of Nilagiri sheep.

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