Trypanosoma gambiense Dutton, 1902
(Figure 1-30)
ETYMOLOGY: This parasite was named after its location along the Gambia river in West Africa.
SYNONYMS:Trypanosoma ugandense Castellani, 1903; Trypanosome castellanii, Kruse, 1903; Trypanosoma hominis Manson, 1903; Trypanosoma fordii Maxwell-Adms, 1903; Trypanosoma nepveui Sambon, 1903; Trypanosoma tullochii Minichin, 1907; Trypanosoma rovumense Beck & Weck, 1913; Trypanosoma nigeriense Macfie, 1913; Castellanella gambiense (Dutton, 1902) Chalmers, 1918.
HISTORY: This is the causative organism of classical "Sleeping Sickness" in humans. This trypanosome was first discovered in human blood in 1901 by Forde, and Dutton proposed the name Trypanosoma gambiense in 1902. That this parasite caused Sleeping Sickness was not suspected by Dutton; Castellani (1903) showed that a trypanosome was present in the cerebrospinal fluid of patients with Sleeping Sickness in Uganda, and suggested that the trypanosome was the causative agent of this disease. The ultimate connection between the forms found in acute disease in the blood (as by Forde and Dutton) and the trypomastigotes present in cerebrospinal fluid of Sleeping Sickness patients was made by Gray and Tulloch (1907) who showed that patients with acute disease would go onto develop Sleeping Sickness. The Tsetse fly was shown to be the vector by Bruce and Nabarro (1903) and Kleine (1909).
LOCATION IN THE HOST: This is a parasite of the blood and tissue fluids (Fig 1-30); it has not been observed in naturally infected cats.
IDENTIFICATION OF THE PARASITE:Trypanosoma gambiense is morphologically indistinguishable from Trypanosoma brucei.
CLINICAL SIGNS AND PATHOGENICITY: There is only one report describing clinical disease in experimentally infected cats (Bogaert, 1962). Four cats were injected with the parasite. Two died after 4 months of infection with rapid weight loss, generalized adenopathy, and splenomegaly. After 7 months, a third cat showed a temporary pelvic limb paralysis; histologic examination revealed slight generalized lymphocytic meningitis without trypanosomes in the spinal fluid. At the end of ten months, the fourth cat showed marked somnolence, myoclonia of the limbs, periodic epileptic seizures, and then a marked ataxia of the cerebellar type. Lymphocytosis but not parasites were found in the cerebral spinal fluid. Upon euthanasia and necropsy eleven and one-half months after infection, this cat showed neurologic changes consistent with cerebral trypanosomiasis: cellular infiltrations in the optic tract, pericapillary infiltrations, uniform meningitis with the lesions increasingly intense near the ectosyvian convolution and the hippocampus.
TREATMENT: This has not been attempted in the cat.
EPIZOOTIOLOGY:Trypanosoma gambiense is considered a parasite of humans that might get into domestic cats by the bite of a tsetse fly.
HAZARDS TO OTHER ANIMALS: Unknown.
HAZARDS TO HUMANS: The hazard to humans would be in the veterinary clinic where an accident with a contaminated needle could serve to introduce the parasite into someone supplying veterinary care.
CONTROL/PREVENTION: There is currently very little known about the prevalence, control, or prevention of the disease in cats. The biology of the parasite would suggest that cats should be protected from Tsetse bites.
REFERENCES:
Bogaert L. 1962. Protozoan Infections. Chapter IX. In: Comparative Neuropathology, Innes JRM & Saunders, Academic Press, New York, USA, pages 473-474.
Bruce D, Nabarro D. 1903. Further information concerning the African sleeping sickness. NY Med J 78:661-662.
Castellani A. 1903. On the discovery of a species of Trypanosoma in the cerebro-spinal fluid of cases of sleeping sickness. Proc Roy Soc, Lond 71:501-508.
Dutton JE. 1902. Note on a Trypanosoma occurring uin the blood of man. Brit Med J 2:881-884.
Forde RM. 1902. Some clinical notes on a European patient in whose blood a Trypanosoma was observed. J Tro Med Lond 5:261-263.
Gray ACH, Tulloch FMG. 1907. Continuation report on sleeping sickness in Uganda. Rep Sleep Sick COm Roy Soc 8:3-80.
Kleine FC. 1909a. Positive Infektiens versuche mit Trypanosomabrucei durch Glossinapalpalis. Dtsch Med Wochenschr 35:469-470
FIGURE 1-30.Trypanosomagambiense trypomastigote in the blood of a mouse stained with Giemsa. One of the two trypmastigotes in the center of this photmicrograph is in the process of dividsion as is evidenced by the presence of two kinetoplasts on the posterior end. Dividing forms like this would not be observed in infections with Trypanosomacruzi.