Fasciolosis is one of the most important parasitic disease of cattle and buffaloes and also widely prevalent in the country. In small ruminants like sheep and goats, it occurs in both acute and chronic form, whereas in large ruminants generally chronic form is common. Acute form of fasciolosis caused by migratory immature flukes in the liver parenchyma is rare in cattle and buffaloes, and is difficult to diagnose as no eggs are detected in faeces¹. However, outbreaks due to chronic fasciolosis in large ruminants have been reported by Gupta and Paul² and Rao et al.³. Cases of acute fasciolosis in buffaloes are rarely reported from India except Banerjee et al.⁴, who has reported one such outbreak in Nainital district of Uttarakhand. Outbreaks of acute fasciolosis in sheep have also been reported by Katiyar and Tewari⁵ and Rao and Madhubala⁶. The present communication deals with morbidity and mortality due to immature F. gigantica infection in cattle and buffaloes of two villages of Bareilly district in Uttar Pradesh.

Morbidity and mortality pattern of the disease were recorded during the investigation in two villages i.e. Shaidpur and Atak under Faridpur block of Bareilly. Clinical symptoms including temperature in affected animals were recorded. Information regarding feed, fodder and water sources were gathered from animals’ owners. It came to the notice of the team that watering source was a pond in the outskirt of village which was in a state of drying condition during the visit i.e. in first week of June. No live snail could be found, however, shells of different species of snails were collected for identification. The blood and faecal samples were collected from sick animals. Faeces were examined for presence of parasitic eggs. Blood was subjected to haematological examination and microbial isolation. The necropsy was performed on two buffaloes. Gross lesions were recorded and morbid samples including liver were collected in 10% formalin for histopathological examination. The tissue samples were processed routinely and cut sections were stained with haematoxylin and eosin, examined under microscope⁷. Livers were subjected for complete teasing to recover the worms.

Clinical history: In first week of June, 2010, Chief Veterinary Officer, Bareilly (U.P.) informed about the mortality and clinical sufferings in cattle and buffaloes in two villages of Faridpur block. Animals were treated symptomatically with antibiotic, antiprotozoal drugs along with minerals and tonic without much improvement in the situation. Upon proper investigation, it was observed that deaths were mostly confined to buffaloes except two bullocks. The disease had occurred since mid May, 2010 leading to death of 30 buffaloes and two bullocks till first week of June. No post-mortem was performed on these animal carcasses. In general, the health of the animals was poor. Ailing animals were showing the symptoms like off feed, low intake of water, dark faeces and death after suffering for 15–20 days. Rectal temperature of the affected animals was normal.

On postmortem examinations of two buffaloes, the body cavities were found to contain large amount of straw colored fluid with fibrin flakes. There was oedema in brisket and dewlap region and petechial hemorrhage in muscles. Liver was found severely affected, enlarged, covered with rust coloured patches, showing haemorrhagic tracts, perforation and presence of large number of immature flukes in the parenchyma (Fig. 1). At places blood filled cavities were also seen in the parenchyma. Hundreds of immature flukes were recovered after teasing of liver and identified as F. gigantica of about 8 weeks age (Fig. 2). Gall bladder contained yellowish watery fluid. Other organs did not show any specific change except presence of mature amphistomes in bile duct and rumen.

Faecal samples collected from ailing animals showed F. gigantica eggs in high counts only in two buffaloes and amphistome eggs in 12 animals. Blood examinations revealed anaemia, increased eosinophil count (9–38%) and no protozoan parasite. On microbiological examinations, no pathogenic organism could be isolated from the blood samples of the affected animals.

Histopathological examinations: The sections of liver showed haemorrhagic tracts, widespread area of necrosis and haemorrhages. Cut sections of flukes were found in the pool of blood in hepatic parenchyma (Fig. 3). The migratory haemorrhagic tracts were full of necrotic debris, cellular and haemorrhagic mass (Fig. 4). Mononuclear cell reaction was observed along the side of necrotic haemorrhagic tracts. Occasionally these were encircled by proliferating connective tissue infiltrated by mononuclear cells.

The gross changes observed in the present investigation were in agreement with the observations made by Rao et al.³ in an outbreak of fasciolosis in buffaloes in Great Nicobar Islands. However, they also recovered adult flukes in bile ducts and eggs in most of the faecal samples and outbreak appeared to be of acute cum chronic nature. Similar pathological changes were also recorded by earlier workers in various animal species⁸,⁹. The general appearance of fluke affected livers consisted of occurrence of haemorrhagic tracts and perforation made by penetrating juveniles. The changes were considered to have occurred due to mechanical damage caused by spines of the flukes during migration and irritant effects of the flukes and their metabolites. The lymphocytic and macrophagic reaction encountered in the liver parenchyma might possibly be due to immune response, as also suggested by Sykes et. al.¹⁰.

History of watering source, presence of shells of Lymnaea auricularia snails in watering source, post-mortem and laboratory findings proved that the disease was caused by immature F. gigantica infection. The structure and size of the flukes indicated the age of these parasites of about 7–8 weeks at the time of deaths of animals in first week of June, 2010 and period of sickness was about 15–20 days. The disease occurred in the villages between middle of May and first week of June indicating that they picked up the infection at any time between second to third week of March. This period might be appropriate time for drying and receding of large water bodies into smaller pond in the outskirt of the village. This was considered for concentration of metacercariae in smaller area which became dangerous for the animals after consuming this contaminated water. Suffering of large number of buffaloes in comparison to cattle might be due to two reasons. Firstly, due to higher population of buffaloes in villages and secondly buffaloes generally enter in water for wallowing purpose and have more chance of getting more contaminated water. Presence of amphistome eggs in all faecal samples indicated infection of mature amphistome parasites of not much pathogenic significance.

Authors thank the Director and Joint Director (CADRAD) of the institute for providing the facilities to carry out this work The help extended by the Chief Veterinary Officer and Veterinary Officers of Bareilly Distt. during disease investigation and collection of samples is duly acknowledged.

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