Blood and Tissue Protozoal Parasites

Additional details about occupationally-acquired cases of parasitic infections, as well as recommendations for post exposure management, are provided elsewhere. 1-3 Effective antimicrobial treatment is available for most parasitic infections. 4 Immunocompromised persons should receive individualized counseling (specific to host and parasite factors) from their personal healthcare provider and their employer about the potential risks associated with working with live organisms. BSL-2 and ABSL-2 practices, 5 containment equipment, and facilities are recommended for activities with infective stages of the parasites discussed in this chapter. Microsporidia, historically considered parasites, are now recognized by most experts to be fungi; however, microsporidia are maintained in the parasitic agent section is this edition. These organisms are discussed here because a laboratoryacquired case of infection has been reported, 6 and most persons currently still look for microsporidia associated with discussion of parasitic agents. Importation of parasitic agents may require CDC and/or USDA importation permits. Domestic transport of this agent may require a permit from USDA

ADULT ALBINO RATS

Though much evidence has been accumulating during recent years to indicate the importance of the reticulo-endothelial cells in resistance and antibody formation, little is known of the more fundamental controlling influences of this mechanism. In previous studies (1-5) we have gathered evidence of the importance of the suprarenal gland in antibody formation through the influence of the water balance in the tissues of the body. That the suprarenal glands are essential in the mechanism of natural resistance has been established through the work of several investigators and in previous work in this laboratory (6-9). In an effort to determine what part the suprarenal gland and other glands of internal secretion play in resistance to protozoan diseases, T. lewisi infection, a common disease of rodents, was studied. T. lewisi infection in the albino rat offers certain advantages for experimental study. * Spontaneous infection is rare, but the disease can be readily transmitted by inoculation of infected blood. Its course can be quantitatively studied. Th

Characterization of a Multisubunit Transcription Factor Complex Essential for Spliced-Leader RNA Gene Transcription in

This article cites 37 articles, 23 of which can be accessed fre

SUMMARY

The function of serum in the composition of culture media for trypanosomes was investigated with Trypanosoma cruxi. Serum supplies stearic acid, essential for the growth of this trypanosome. A liquid heat-sterilizable medium, composed of peptone and known chemicals is described. The growth of T. cruxi in this medium reached 70 x lo8 trypanosomes/ml

The Configuration of DNA Replication Sites within the

Abstract. The kinetoplast is a concatenated network of circular DNA molecules found in the mitochondrion of many trypanosomes. This mass of DNA is replicated in a discrete "S " phase in the cell cycle. We have tracked the incorporation of the thymidine analogue 5-bromodeoxyuridine into newly replicated DNA by immunofluorescence and novel immunogold labeling procedures. This has allowed the detection of particular sites of replicated DNA in the replicating and segregating kinetoplast. These studies provide a new method for observing kinetoplast DNA (kDNA) replication patterns at high resolution. The techniques reveal that initially the pattern of replicated DNA is antipodal and can be detected both on isolated com-plexes and in replicating kDNA in vivo. In Trypanosom

Glycosylphosphatidylinositol-Dependent Protein Trafficking in

We have previously demonstrated that glycosylphosphatidylinositol (GPI) anchors strongly influence protein trafficking in the procyclic insect stage of Trypanosoma brucei (M. A. McDowell, D. A. Ransom, and J. D. Bangs, Biochem. J. 335:681-689, 1998), where GPI-minus variant surface glycoprotein (VSG) reporters have greatly reduced rates of endoplasmic reticulum (ER) exit but are ultimately secreted. We now demonstrate that GPI-dependent trafficking also occurs in pathogenic bloodstream trypanosomes. However, unlike in procyclic trypanosomes, truncated VSGs lacking C-terminal GPI-addition signals are not secreted but are mistargeted to the lysosome and degraded. Failure to export these reporters is not due to a deficiency in secretion of these cells since the N-terminal ATPase domain of the endogenous ER protein BiP is efficiently secreted from transgenic cell lines. Velocity sedimentation experiments indicate that GPI-minus VSG dimerizes similarly to wild-type VSG, suggesting that degradation is not due to ER quality control mechanisms. However, GPI-minus VSGs are fully protected from degradation by the cysteine protease inhibitor FMK024, a potent inhibitor of the major lysosomal protease trypanopain. Immunofluorescence of cells incubated with FMK024 demonstrates that GPI-minus VSG colocalizes with p67, a lysosomal marker. These data suggest that in the absence of a GPI anchor, VSG is mistargeted to the lysosome and subsequently degraded. Our findings indicate that GPIdependent transport is a general feature of secretory trafficking in both stages of the life cycle. A working mode

of suppressor APCs

prevents experimental autoimmune encephalomyelitis in DBA/1 mice through inductio

AETIOLOGY TRYPANOSOMOSIS (TSETSE-TRANSMITTED) Aetiology Epidemiology Diagnosis Prevention and Control References

Flagellated protozoan parasites that live in the blood, lymph and various tissues of their vertebrate hosts: Trypanosoma congolense, T. vivax, and to a lesser extent T. brucei brucei. T. uniforme and T. simiae are other, less common tsetse-transmitted species. T. congolense and T. vivax are mainly intravascular parasites while T. brucei has an affinity for tissues. Several types of T. congolense can be distinguished by molecular biology; the most common and pathogenic one in cattle is the type “savannah”, the other ones (type ‘forest ’ and ‘Kilifi’) are less pathogenic and have different host affinity. Mixed trypanosome infections with two or three species are common. Resistance to physical and chemical action Disinfectants/chemicals: Controlling arthropod vectors and preventing access to host species is important in preventing new infections. Disinfection does not prevent spread of disease (blood-borne parasite). Survival: These agents can only survive in blood, body fluids and tissues of animal hosts and within tsetse flies. Mechanically transmitted T. vivax cannot survive long outside the host. Agents disappear within a few hours after death of the vertebrate host. EPIDEMIOLOGY Tsetse flies infest 10 million square kilometres and affect 37 countries, mostly in Africa, where it is known as ‘Nagana’. It is the most economically important livestock disease of Africa, especially of cattle

TRYPANOSOMA EVANSI INFECTIONS (INCLUDING SURRA) AETIOLOGY Aetiology Epidemiology Diagnosis Prevention and Control References

Trypanosoma evansi. T. equinum in South America is a dyskinetoplastic variant of T. evansi and not a separate species. Transmitted mechanically from infected blood of animals, and is not capable of cyclical development in tsetse Glossina spp. Morphologically indistinguishable from T. brucei. Resistance to physical and chemical action Chemicals/Disinfectants: Controlling arthropod vectors and preventing access to host species is important in preventing new infections. Disinfection does not prevent spread of disease (blood-borne parasite). One minute exposure to ultraviolet light prevents infection. Survival: Trypanosomes only survive short periods outside the host. T. evansi disappears quickly from the carcass after death. Flies no longer transmit the parasites after 8 hours. EPIDEMIOLOGY T. evansi has a wide host range. In some countries incidence of surra increases significantly furing the rainy season when biting fly populations have greatly increased. Surra affects mainly camels and horses but buffaloes and cattle are also affected. Other species that develop severe disease include donkeys, mules, deer, llamas, dogs, cats, cattle and buffalo. Sheep, goats, pigs and elephants may occasional develop mild or chronic disease. Camel raising in Africa and buffalo production in Asia are severely affected