PURSE 2001
Permanent URI for this collection
Browse
Browsing PURSE 2001 by Author "Arulkanthan, A."
Now showing 1 - 3 of 3
Results Per Page
Sort Options
- ItemA study on the developmental cycle of dactylogyrus intermedius in Gold -Fish ( Carassius Auratus)(University of Peradeniya, Peradeniya, Sri Lanka, 2001-11-16) Perera, U. F. R.; Rajapakse, R. P. V. J.; Arulkanthan, A.Dactylogyrus intermedius (gill fluke) is a monogenean trematode known to cause heavy morbidity and mortality in gold-fish (particularly in young fry) in many commercial aquariums in Sri Lanka. Information on the clinical presentation of the disease and the life cycle pattern of D. intermedius infection in gold-fish under local conditions are scarce. Therefore, with a view of proposing measures to control this infection in Sri Lankan aquariums, the above mentioned aspects were studied. Four hundred gold-fish fry (age; 3-4 weeks), which were naturally infected with D. intermedius, was obtained from an aquarium in Colombo. After observing the clinical features, 50 randomly selected fry were sacrificed and gross lesions in the gills were noted. Ten infected fry were kept in a tank for 48 hours to determine the mean spawning rate. The rest of the infected fry were used to obtain eggs for life-cycle studies. Freshly spawned eggs (n=250) were incubated in de-chlorinated water at room temperature (26-29 °C) and the eggs were examined twice daily for larval development. In a subsequent experiment, two groups (A and B) of uninfected gold-fish fry (n=10/group) were kept in separate tanks and on Day 0 of the experiment freshly spawned eggs (250 eggs/tank) were added to each tank. On Day 7 of the experiment, fish from group A was removed from the tank and kept individually in 10 petri dishes and examined twice daily for the presence of freshly spawned eggs. Group B was transferred to a new tank on Day 7 of the experiment; thereafter one fish was sacrificed on every other day and skin scrapings and gills were examined for developmental stages. The common clinical signs observed in infected gold-fish fry varied but the salient features were widely opened operculum, rapid breathing, and crowding near the surface with gaping mouths. At necropsy, varying numbers of D. intermedius (range; 4-52) were found to be attached to the gills which were pale in colour with a heavy blanket of mucus. The mean spawning rate was 11 eggs/fluke/day and the operculated eggs (dimensions; 40-47.5 x 72.5-80 urn) sunk to the bottom of the tank after spawning. The larval development within the eggs was evident by 24 to 48 hours post incubation. Free swimming ciliated oncomiracidium (110 - 115 x 40 - 45 µm) emerged from the eggs by 2.5 to 6 days post incubation and the percentage of hatching was 85-90 %. Immature flukes were present on the skin and gills, whereas the mature flukes (112.5-137.5 x 312.5-337.5 µm) were attached either on the primary or secondary lamellae of the gills. The duration taken to complete the life cycle (eggs to eggs) at 26-29 °C was found to be 12-15 days. It is suggested that physical removal of eggs from the tank by bi-weekly siphoning off the sediment and coupled with a chemical treatment in the form of continuous immersion for a minimum period of 15 days would control this infection by disrupting the life cycle.
- ItemOccurrence of Cyptosporidium Oocysts in a Natural Population of Non-Human primates in Sri Lanka(University of Peradeniya, Peradeniya, Sri Lanka, 2001-11-16) Ekanayake, D. K.; Horadagoda, N. U.; Sanjeevani, G. K. M.; Arulkanthan, A.; Dittus, W. P. J.Cryptosporidium is an enteric protozoan parasite responsible for diarrhoea in children, young animals and immunocompromised hosts. In Sri Lanka, the infection has been reported in man and a wide variety of domestic animals. The objective of the present work was to determine the occurrence of the infection in a natural population of monkeys and the association of the infection with the habitat. The study was conducted in nonhuman primates (infants to adults) that habituated separate locations in the natural sanctuary of the Polonnaruwa archaeological reserve, which bordered a human habituated area. Faecal samples were collected from 117 monkeys comprising 81 toque monkeys (Macaca sinica), 21 gray langurs (Semnopithicus entellus) and 15 purple-faced langurs (Trachypithecus senex). The samples were examined for cryptosporidium oocysts using Sheather's sucrose floatation method followed by staining with the modified Ziehl Neelsen technique. The oocysts were also measured using an ocular micrometer and selected positive samples were stained with Nigrosin, Giemsa and modified trichrome to verify the identification of the parasite. In addition, the oocysts were quantified as described by Noordeen et al (Veterinary Parasitology: 2000: 93; 95-101). The identification of the parasite was based on staining characteristics and micrometry (2-6 urn). Of the 117 specimens examined, 28.2 % (33/117) were positive for cryptosporidium oocysts. An overwhelming proportion of the infected animals (97 %) were from home ranges, which overlapped with human habituated areas as compared with non-human habituated areas (3 %). The prevalence of the infection varied between the species of monkeys with gray langurs having the highest prevalence (38.1 %) followed by toque monkeys (30.9 %); none of the purple-faced langurs were positive for cryptosporidium oocysts. Twenty seven percent of the infected animals had a low oocyst counts (1 - 999 oocysts per gram of faeces), 51 % had moderate counts (1000 - 4999) while 18 % had high counts (>5000). The mean oocyst count of cryptosporidium positive samples was 3633 (166 - 34,250). Except for one juvenile toque monkey that had mild diarrhoea with a high oocyst count (34,250), all cryptosporidium positive animals were asymptomatic. This is the first study to examine the occurrence of cryptosporidium in nonhuman primates in Sri Lanka. The presence of the infection in the three species of monkeys studied was closely related to their habitat. Despite the variation in the oocyst counts, a majority of the infected animals were asymptomatic suggesting that an ecological balance exists between the hosts and the parasite in the study area.
- ItemSurgical removal of a filarial worm in the eye of a dog(University of Peradeniya, Peradeniya, Sri Lanka, 2001-11-16) De Silva, D. N.; Wijayawardhane, K. A. N.; Arulkanthan, A.A two year old, male Germen Shepherd weighing 30 kg was brought for treatment to the Veterinary Teaching Hospital, University of Peradeniya with a complaint of progressive corneal opacity, irrespective of the treatment. General body condition of the animal appeared to be satisfactory. The animal had been initially treated with eye drops containing antibiotics and steroids for about one month. Subsequently it had been treated for secondary glaucoma with "Timolol" eye drops and acetazolamide 10 mg/kg orally, twice daily for one week. Both eyes were carefully examined using the ophthalmoscope. Sclera was severely injected and the cornea was almost completely opaque. Pupillary reflex was sluggish even though the lens was not clearly visible and the palpebral reflex was normal. A slender, white coloured worm was seen moving in the aqueous humour. The eyeball was protruded and the left eye was apparently normal. A blood smear and a blood drop were examined for blood parasites. Special attention was focused on filariasis. The drop and the Knott's technique yielded negative results on blood, collected eight hourly within a day. A surgical intervention was suggested to remove the worm. Animal was starved for six hours prior to the surgery and was pre medicated with chlorpromazine. Ketamine hydrochloride was used as the anesthetic agent to prevent the ventral deviation of the eyeball. Peri-limbal incision was made laterally at the sclero-corneal junction. A small amount of aqueous humour was released together with the worm of about 3 inches long. Incision was sutured with surgical silk. Postoperative treatment was continued with eye drops contammg gentamycin, betamethasone and parentral antibiotics for a few days. The worm was identified as a male Dirofilaria repens.