abstract
Cytology tests are regularly performed as part of the Lisbon Zoo dolphin (Tursiops truncatus) medical program. During a routine respiratory tract examination, a cytology sample stained with New Methylene Blue, and observed at both 100X and 400X magnification, showed a "Trypanoplasma-like" flagellate. Although the flagellate was initially only observed in only one individual, subsequent examination revealed the presence of the same organisms in all four dolphins living in the same pool.
Sputum samples were sent to the parasitology department of LNIV (Laboratório Nacional de Investigação Veterinaria), where Giemsa stained smears were examined. The spindle-shaped flagellates containing two purple and blue masses of irregular shape and size (a nucleus and a kinetoplast). A few of the parasites had fragments of kinetoplasts but an undulating membrane was not prominent. These morphological features suggest a kinetoplastid of the family Bodonidae Butschli, 1987 and genus Cryptobia J. Leidy, 1846.1
Hourly cytological examinations were initiated. All of the dolphins showed the presence of the flagellate, but not in all samples. It is important to note that if the samples were examined immediately after collection, the number of flagellates observed was much greater than when samples where examined several hours later.
Four months after the first parasite was observed, all the dolphins presented with intermittent coughing throughout the day. At the same time, we observed increased numbers of leukocytes in sputum samples, and a change in the regular respiratory tract flora, including the presence of Kyaroikeus spp., a non-pathogenic ciliate.2 Hemograms also demonstrated eosinophilia, and one animal had a marked leukocytosis.
Considering the evolution of the cytology and blood results and coughing, therapy was initiated using the following protocol: Metronidazole (Flagyl®) 7.0 mg/ Kg BID for 10 days followed by an interval of 10 days, after which the treatment was repeated at the same dose for an additional seven days. In one case, a complementary treatment with an antifungal drug, Fluconazole (Diflucan®) 2.0 mg/kg BID, was administered due to the overgrowth of Candida glabrata. Following this treatment, the parasites were no longer detected, and coughing abated.
We do not know how the parasite was introduced to our collection. Other authors have described flagellates in the upper respiratory track, but none were associated with clinical abnormalities.3,4 It is interesting to note that there are nearly 10 species of Trypanoplasma described in marine fish.5 We strongly suspect that aerosol transmission was responsible for the spread between our animals. Each animal presented with a slightly different response to the parasite's presence, both locally and systemically. As this abstract is submitted, the treatment has just finished. Cytology tests and clinical signs remain normal in all animals. We will continue routine cytology monitoring of these dolphins.
References
1. PTK Woo (2003) Cryptobia (Trypanoplasma) salmositica and salmonid cryptobiosis. Journal of Fish Diseases, 26, 627-646.
2. Dailey DM. (2001) Parasitic Diseases in CRC Handbook of Marine Mammal Medicine. Dierauf, L and Gulland, M.D. Editors, CRC Press.1063 pp.
3. Poynton SL, et al. (2001) A novel trypanoplasm-like flagellate Jarrellia atramenti n. g., n. sp. (Kinetoplastida: Bodonidae) and ciliates from the blowhole of a stranded pygmy sperm whale Kogia breviceps (Physeteridae): morphology, life cycle and potential pathogenicity. Diseases of Aquatic Organisms. 22: 191-201.
4. Sweeney J, et al. (1999) Handbook of Cetacean Cytology, Dolphin Quest, Inc. 41 pp.
5. Lom J, Dykova I. (1992) Protozoan parasites of fishes. Elsevier Science Publishers B.V. 315 pp.