Trypanosoma brucei

Trypanosoma brucei

<p align="CENTER"><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: large;"><i><b>Trypanosoma brucei</b></i></span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: large;"><b> Plimmer and Bradford, 1899</b></span></span></span></p> <p align="JUSTIFY"><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><i>Trypanosoma brucei</i></span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"> is morphologically indistinguishable from </span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><i>Trypanosoma gambiense</i></span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"> and </span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><i>Trypanosoma rhodesiense</i></span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;">. Together, these three parasites are considered to form a tsetse transmitted complex (see Hoare, 1967), of which </span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><i>T. gambiense</i></span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"> is almost exclusively human wherein chronic disease is produced, </span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><i>T. rhodesiense</i></span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"> is a zoonosis from African ungulates producing fulminant disease in humans, and </span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><i>T. brucei</i></span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"> occurs mainly in animals and may or may not cause human disease. Hill (1955) summarizes the reports of these three species in the cat including several personal communications with workers in the field, but in most cases only very minor notes have been presented by those cited by Hill. Thus, there seems to be little or no literature concerning the infection of cats with </span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><i>T. rhodesiense</i></span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;">. Experimental infections of cats with </span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><i>Trypanosoma gambiense</i></span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"> has been examined on at least one occasion.</span></span></span></p> <p align="JUSTIFY"><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><b>ETYMOLOGY:</b></span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"> The parasite is named after Major David Bruce.</span></span></span></p> <p align="JUSTIFY"><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><b>SYNONYMS:</b></span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><i>Trypanosoma pecaudi</i></span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"> Laveran, 1907; </span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><i>Trypanosoma togolense</i></span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"> Mesnil &amp; Brimont, 1909; </span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><i>Trypanosoma ugandae</i></span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"> Stephens &amp; Blacklock, 1913; </span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><i>Trypanosoma multiforme</i></span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"> Kinghorn et al., 1913; </span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><i>Trypanosoma anceps</i></span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"> Bruce et al., 1914; </span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><i>Trypanosoma dukei</i></span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"> Knuth &amp; duToit, 1921.</span></span></span></p> <p align="JUSTIFY"><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><b>HISTORY:</b></span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"> The parasite was found to be the causative agent of Nagana in cattle by Sir David Bruce in 1894 who recognized the trypanosome in the blood of cattle and showed that it could be transmitted by inoculation into horses and dogs where it caused acute disease (Hoare, 1967). Bruce also showed that naturally infected Tsetse flies were involved in the transmission of the parasite, but it was not until the work of Kleine (1909 a&amp;b) that it was shown that a period of development within the Tsetse was required for transmission to occur.</span></span></span></p> <p align="JUSTIFY"><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><b>GEOGRAPHICAL DISTRIBUTION:</b></span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"> This parasite is distributed throughout the range of the tsetse fly vector in western Africa. The mammalian reservoirs of infection are considered to be various forms of African antelope.</span></span></span></p> <p align="JUSTIFY"><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><b>LOCATION IN THE HOST:</b></span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"> The parasite is considered to be a parasite of blood and tissue fluids. Although in cats, the parasite has only been observed in the blood.</span></span></span></p> <p align="JUSTIFY"><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><b>IDENTIFICATION OF THE PARASITE:</b></span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><i>Trypanosoma brucei</i></span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"> is the type of trypanosome that has two stages present in the blood, a short and stumpy form with no free flagellum and a long and slender form with a free flagellum. The short form has a length of around 18 m (range: 12-26 m) while the long form has a length of 29 m (range: 23-42 m).</span></span></span></p> <p align="JUSTIFY"><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"> In Giemsa-stained blood films, the trypanosomes can be examined, and dividing forms can be seen. The slender forms will typically be S-shaped with 3 to 5 undulations of the undulating membrane throughout the length of the cell body. The free flagellum will be about one-half to one-third of the length of the cell. The nucleus will be near midbody, and the rather small kinetoplast will be near the posterior end of the cell body. In the stumpy forms of the parasite, the cell often takes on more of a C-shape or L-shape, the nucleus will be near the end of the cell body, and there will be no free flagellum. There will still be around three undulations of the membrane along the cell surface.</span></span></span></p> <p align="JUSTIFY"><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><b>LIFE CYCLE:</b></span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"> The transmission of </span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><i>Trypanosoma brucei</i></span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"> typically requires the development within a Tsetse fly (genus </span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><i>Glossina</i></span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;">) wherein development of infective stages occur within the gut and salivary glands (Kleine 1909 a&amp;b). The trypano somes are transmitted to the next host through the bite of the fly. Transmission of the parasite can also be caused by inoculation of blood containing the organisms as might occur with a dirty needle, the contaminated mouthparts of a horse fly (tabanid), or by transfusion. In cats, it has been shown that they can also be transmitted by feeding on the meat of an infected goat with parasites in circulation; 3 of 17 cats became infected in this manner (Moloo et al., 1973).</span></span></span></p> <p align="JUSTIFY"><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"> In cats inoculated with blood, trypanosomes will appear in the blood stream beginning 5 days after inoculation (Kanthack et al., 1899). When cats were fed goat meat, trypanosomes first appeared in the blood 31 to 38 days after they had been fed the infected meat; these cats were killed soon after the infection was detected in the blood. In cats fed an infected mouse or an infected guinea pig, the prepatent periods were 44 and 25 days, respectively (Laveran and Mesnil, 1912). In general, it is considered that the infected cat seldom lives long enough to play a major role in transmis sion.</span></span></span></p> <p align="JUSTIFY"><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><b>CLINICAL PRESENTATION AND PATHOGENESIS:</b></span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"> Cats that have been experimentally infected die within 22 to 26 days after infection (Kanthack et al., 1899). These cats were noted to develop pyrexia and changes in the eyes including an aqueous flare and conjunctivitis, and edema of the face and eyelids. At necropsy, these cats were found to have pronounce wasting with generalized lymphadenopathy, splenomegaly, hepatomegaly, and pleura and pericardium hemorrhage.</span></span></span></p> <p align="JUSTIFY"><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"> A naturally infected cat (Hill, 1955) was noted to be listless and off its food with a dry rough hair coat and pale mucous membranes. There was edema and erythema of the head region. In this cat, both eyes were acutely affected with photophobia, lacrimation, conjunctivitis and keratitis; in the right eye there was pannus, hypopyon, and hypertony. Within 6 days of the initial presentation, the cat became blind and too weak to stand.</span></span></span></p> <p align="JUSTIFY"><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><b>TREATMENT:</b></span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"> Treatment of only one infected cat has been reported in the literature (Hill, 1955). This cat was treated with antycide methyl-sulphate (6.0 mg/kg body weight) subcutaneously. It began to eat again by the third day after treatment, and the hypopyon began to disappear. Both eyes appeared normal 8 days after treatment. This cat did relapse a few weeks later, again with ophthalmologic signs, and was again treated. Relapse developed again several months later, and following treatment and another relapse, the cat was euthanatized.</span></span></span></p> <p align="JUSTIFY"><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><b>EPIZOOTIOLOGY:</b></span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><i>Trypanosoma brucei</i></span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"> is considered a parasite of African ungulates that can get into domestic cats by the bite of a tsetse fly.</span></span></span></p> <p align="JUSTIFY"><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><b>HAZARDS TO OTHER ANIMALS:</b></span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"> As noted above, cats seldom live long enough after infection to serve as major sources of infection to other animals.</span></span></span></p> <p align="JUSTIFY"><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><b>HAZARDS TO HUMANS:</b></span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"> 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.</span></span></span></p> <p align="JUSTIFY"><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><b>CONTROL/PREVENTION:</b></span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"> There is currently very little known about the control and prevention of the disease in cats. The biology of the parasite would suggest that cats should be protected from Tsetse bites and not fed meat of wild game that might be infected.</span></span></span></p> <p align="JUSTIFY"><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><b>REFERENCES:</b></span></span></span></p> <p align="JUSTIFY"><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;">Hoare, 1967 </span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><b>NEED REFERENCE</b></span></span></span></p> <p align="JUSTIFY"><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;">Hill DH. 1955. Trypanosoma brucei in the cat. Brit Vet J 111:77-80.</span></span></span></p> <p align="JUSTIFY"><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;">Kanthack AA, Durham HE, Blandford WFH. 1899. On Nagana, or TseTse Fly disease. Proc Roy Soc 64:100-118.</span></span></span></p> <p align="JUSTIFY"><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;">Kleine FC. 1909a. Positive Infektiens versuche mit </span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><i>Trypanosoma</i></span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><i>brucei</i></span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"> durch </span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><i>Glossina</i></span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><i>palpalis</i></span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;">. Dtsch Med Wochenschr 35:469-470</span></span></span></p> <p align="JUSTIFY"><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;">Kleine FC. 1909b. Weitere Beobachtungen über Tsetsefliegenu nd Trypanosomen. Dtsch Med Wochenschr 35:1956-1958.</span></span></span></p> <p align="JUSTIFY"><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;">Laveran A, Mesnil F. In Masson’s</span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><span style="text-decoration: underline;"> Trypanosomas et Trypanosomiases.</span></span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"> Paris, France.</span></span></span></p> <p align="JUSTIFY"><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;">Moloo SK, Losos GJ, Kutuza SB. 1973. Transmission of Trypanosoma brucei to cats and dogs by feeding on infected goats. Ann Trop Med Parasitol 67:331-334.</span></span></span></p>