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2010, Vol. 5 No. 2, Article 72


Echinococcus infestation in lung of Nilgai
(Boselaphus tragocamelus)

Geeta Devi Leishangthem1, Aparajita Choudhury2, Khangembam Victoria Chanu3* and Gautam Patra4



1Department of Pathology,
All India Institute of Medical Sciences, Ansari Nagar, New Delhi.
2Veterinary Hospital, Society for Prevention of Cruelty to Animal, Noida, UP.
3Department of Veterinary Biochemistry,
College of Veterinary Sciences and Animal Husbandry, Central Agricultural University, Selesih, Aizawl, Mizoram.
4Department of Veterinary Parasitology,
College of Veterinary Sciences and Animal Husbandry, Central Agricultural University, Selesih, Aizawl, Mizoram.



*Corresponding Author; e-mail address: vickygoitu@gmail.com



The present communication places on record an accidental finding ” hydatidosis” in a Nilgai that was under treatment for injury to hind limbs but succumbed subsequently to the wound infection. Postmortem examination revealed a single cyst protruding on the right anterior lobe of the lung. The cystic fluid stained with Gentian violet showed numerous hydatid sand of Echinococcus granulosus. Histopathological observations of the affected lung tissue and cyst wall were suggestive of hydatidosis.


Echinococcosis, histopathology, lung, Nilgai.


Echinococcosis or Hydatid disease is a zoonotic infection caused by cystic larval stage of tapeworm Echinococcus granulosus. It is worldwide in distribution. Foci of hydatid disease also exist in India with highest prevalence in Andhra Pradesh and Tamil Nadu (11). In man the disease is characterized by a slow but steady progression of the parasitic lesions and a high mortality rate in untreated patients (1). The metacestode stage proliferates in the intermediate and aberrant hosts, predominantly in the liver by exogenous budding and by invading surrounding tissues comparable to a malignant tumour (2).
Dog and fox are the usual hosts of the adult tapeworm. These animals serve as the main source of infection to other animals and man as well. The infection may be contracted by the animals through ingestion/inhalation of eggs released from tapeworm segments passed in the feces by usual hosts (3).
Nilgai, commonly called Blue bulls is an antelope, mainly found in the lower plains stretching from the foothills of the Himalayas in the north to Karnataka in the south of India. The animal is a wild herbivore thriving on grasses, leaves, buds and fruits. It may also get infested by consuming the grasses, water etc. contaminated with the eggs of Echinococcus. 


A female Nilgai (Boselaphus tragocamelus) was brought to the Veterinary Hospital, Society for Prevention of Cruelty to Animal (SPCA), Noida with injury to the hind limbs but it subsequently succumbed to wound infection. Post mortem examination revealed presence of a single cyst in the lung. The cystic fluid was collected and centrifuged at 1000 rpm for 10 min. The sediment was then stained with 3% Gentian violet. The lung was preserved in 10% buffered formalin and processed for routine histopathological examination. Following the routine procedure, the lung tissues were embedded in paraffin and sections of 5mm thickness were cut. The sections were then stained with hematoxylin and eosin and examined under microscope (10).


On post mortem examination, a single cyst measuring about 3x2.5x3 cm was found protruding on the right anterior lobe of the lung. The cyst contained about 15 ml of proteinaceous fluid. Upon drainage of fluid, the inner surface of the cyst wall showed a folded appearance and displayed numerous white colored granular structures. The fluid stained with Gentian violet revealed numerous hydatid sand of Echinococcus granulosus (Fig. 1). Histopathological examination of the lung tissue exhibited extensive tissue reaction characterized by various degrees of cellular infiltration and fibrosis along with numerous brood capsules attached to the cystic membrane (Fig. 2). The bronchial epithelium was hyperplastic and peri-bronchiolar blood vessels were engorged with blood. Necrotic material and many giant cells, surrounded by an outer layer comprising of macrophages, lymphocytes and a few numbers of epitheloid histocytes, were seen (Fig. 3). Outer wall of the cyst showed typical echinococcal hyalinous laminated membrane (Fig. 4).


In the natural cycle, dogs and other canids are typical definitive hosts and a wide range of mammals, including sheep, cattle, pig, buffalo, goat, camel, horse and man, can serve as the intermediate host by harboring the metacestode stage (12,13,14). The infection of carnivores with immature or mature intestinal stages of E. granulosus does not cause morbidity, whereas the invasion of various organs (mainly liver and lungs) of intermediate or aberrant hosts by metacestode can cause severe and even fatal disease (hydatidosis). Man is an accidental intermediate host, as entry of the larval forms into humans represents an end stage in its life cycle. The outcome of infection in livestock and humans is cyst development in the liver, lungs, or other organ systems. The lungs and liver appear to be the sites of predilection (13).
In the present study, the cyst was an accidental finding in the Nilgai. The Nilgai may serve as a reservoir of E. granulosus and foxes and wild dogs which are the definitive hosts, may get infected by ingestion of meat from the infected animal. Domestic dogs may, under certain conditions, get involved in the otherwise largely wildlife-based transmission, and thereby greatly increase the infection pressure to humans.


The authors are grateful to Chief, SPCA, Noida for providing the samples and Dr. Amit Kumar Dinda, Additional Professor, Department of Pathology, AIIMS, New Delhi for providing the facilities for histopathological studies.


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Fig. 1: Hydatid Sand of E. granulosus

Hydatid Sand of E. granulosus

Fig. 2 & 3: Histopathological sections of lung showing extensive tissue reaction along with inflammatory cells infiltrate around the necrotic areas

Histopathological sections of lung showing extensive tissue reaction along with inflammatory cells infiltrate around the necrotic areas

Histopathological sections of lung showing extensive tissue reaction along with inflammatory cells infiltrate around the necrotic areas

Fig. 4: Cyst wall showing laminated membrane

Cyst wall showing laminated membrane



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