Trypanosoma evansi

Trypanosoma evansi

<p align="CENTER"><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: large;"><i><b>Trypanosoma evansi</b></i></span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: large;"><b> (Steel, 1885) Balbiani, 1888</b></span></span></span></p> <p align="CENTER"><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: large;"><b>(Figure 1-31)</b></span></span></span></p> &nbsp; <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;"> This parasite is named after Dr. Griffith Evans, the British veterinarian who discovered the parasite.</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>Spirochaete evansi</i></span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"> Steel, 1885; </span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><i>Trypanosoma elmassiani</i></span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"> Lignières, 1902; </span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><i>Trypanosoma soudanense</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 hiipicum</i></span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"> Darling, 1910; </span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><i>Trypanosoma venezuelense</i></span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"> Mesnil, 1910; </span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><i>Trypanosoma annamense</i></span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"> Laveran, 1911; </span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><i>Trypanosoma cameli</i></span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"> Pricolo &amp; Ferror, 1914; </span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><i>Trypanosoma macracanum</i></span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"> Sergent, Lhéritier &amp; Belleval, 1915; </span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><i>Trypanosoma ninae kohl-yakimov</i></span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"> Yakimoff, 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;"> This was the first pathogenic trypanosome to be discovered. Dr. Griffith Evans discovered the organisms in 1880 in the blood of horses and camels in India that were suffering from a disease called Surra. Mechanical transmission by biting flies was first shown by Rogers (1901).</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>GEOGRAPHIC DISTRIBUTION:</b></span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"> The organism is found in Africa north of the Sahara, Asia, and Central and South America.</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;"> These parasites are parasites of the blood stream and tissue fluids. In the cat, organisms have 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;"> The morphology of this parasite (Fig 1-31) is indistinguishable from that 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;">.</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;"> This parasite is transmitted between hosts by mechanical transmission by biting flies (Rogers, 1901). In South America, transmission has also been shown to be possible through the bite of vampire bats (</span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><i>Desmodus rotundus</i></span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;">) (Dunn, 1932).</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;"> Typically, this parasite is thought of as causing disease in horses, camels, and elephants, and dogs wherein there is emaciation and edema. There have been few reports in cats.</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 presented with lethargy and inappetence, sunken eyes, and incoordination (Paikne and Dhake, 1974). Poisoning was the expected etiology. The animal died and a necropsy was performed. Blood smears revealed numerous </span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><i>Trypanosoma evansi</i></span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"> organisms. There was perivascular cuffing around vessels in the brain.</span></span></span></p> <p align="JUSTIFY"><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"> At least two studies have been performed in which cats have been experimentally infected (Choudhury and Misra, 1972; Scheidle, 1982). In the earlier report, cats were inoculated intraperitoneally. The trypanosomes appeared in the circulation 14 to 15 days after infection. Young cats could succumb during the first peak parasitemia, but if they survived, 4-day-long peaks of parasitemia appeared every two weeks. During the peak parasitemias, the cats showed signs (</span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><b>Dwight, what signs??) </b></span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"> of infection. In the later report, three cats were inoculated with 1,500 trypanosomes. Two days after infection, parasites were detectable in the blood; after two weeks of infection, there were 70,000 trypanosomes observed per cubic millimeter of blood. The body temperature of the infected cats seldom exceeded 40• C. After nine days of infection, the cats were severely anemic with, which was the major observation at necropsy. </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;"> Two experimentally infected cats were treated with Berenil, 4-4'-diamidino-diazoamino-benzol-diaceturat (</span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><b>dose??)</b></span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"> (Scheidle, 1982). A second treatment was given 2 days later because the cats still had low parasitemias one day after the first treatment. After the second treatment, trypanosomes were not observed for 8 to 20 days, but they then appeared and rose to near the pretreatment levels of 70,000 trypanosomes per l.</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 evansi</i></span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"> is considered to use cattle and buffalo as the reservoir host. Transmission to horses and dogs is not uncommon, but it is unclear how often cats may 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>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;"> Unknown.</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;"><i>Trypanosoma evansi</i></span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"> is not considered to be a human pathogen. However, precautions should be taken to reduce potential hazards to humans 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 prevalence, control, or prevention of the disease in cats. The biology of the parasite would suggest that cats should be protected from fly bites.</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;">Choudhury A, Misra KK. 1972. Experimental infection of </span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><i>T. evansi</i></span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"> in the cat. Trans Roy Soc Trop Med Hyg 66:672-673.</span></span></span></p> <p align="JUSTIFY"><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;">Dunn LH. 1932. Experiments in 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</i></span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><i>hippicum</i></span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"> Darling with the vampire bat, </span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><i>Desmodus</i></span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><i>rotundus</i></span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><i>murinus</i></span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"> Wagner, as a vector in Panama. J Prevent Med 6:415-424.</span></span></span></p> <p align="JUSTIFY"><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;">Paikne DL, Dhake PR. 1974. Trypanosomiasis in a deomestic cat (</span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><i>Felis</i></span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"><i>catus</i></span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;">). Ind Vet J 51:10</span></span></span></p> <p align="JUSTIFY"><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;">Rogers L. 1901. The transmisison of </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>evansi</i></span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"> by horseflies and other experiments pointing to the probable identity of Surra and Nagana or Tsetse-fly disease in Africa. Proc Roy Soc Ser B 68:163-170.</span></span></span></p> <p align="JUSTIFY"><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;">Scheidle G. 1982. Das Infektionsverhalten von </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>evansi</i></span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"> (Stamm Manila) in vershiedenen Tierarten. Dissertation, Ludwig-Maximillians-Universität München. 53 pages</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>FIGURE 1-31.</b></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>evansi</i></span></span></span><span style="color: #000000;"><span style="font-family: 'Times New Roman', serif;"><span style="font-size: medium;"> in the blood of a horse. Giemsa stain. As in Fig 1-16, trypomastigotes in this preparation can be observed to be undergoing cellular division.</span></span></span></p>