Disseminated intravascular coagulation in trypanosomiasis

The influence of parasitism by Trypanosoma cruzi in the hematological parameters of the white ear opossum (Didelphis albiventris) from Campo Grande, Mato Grosso do Sul, Brazil

Considered ecologically generalist, Didelphis albiventris is reported as reservoir for different species of parasites, especially Trypanosoma cruzi. However, the knowledge about the influence of T. cruzi on hematological parameters of free-living opossum remains scarce. The present study aimed to evaluate the influence of T. cruzi on hematological parameters of white-ear opossums (D. albiventris) from Campo Grande, Mato Grosso do Sul, Brazil. The blood samples and biometric data were collected from 40 opossums captured by Tomahawk and Sherman traps in six urban forest fragments located in the city. The health of these animals was inferred, mainly, by means of blood parameters (PCV, RBC, WBC, MCV and WBC differential). Molecular detection of T. cruzi infection was performed by nested polymerase chain reaction (nPCR), using 18S and 24Sα rDNA region as target. Paired-t-test and simple linear regression were used for statistical analysis. No significant difference was observed between the averages of hematological variables in relation to gender and body condition. The molecular diagnosis showed that 32.5% (13/40) of the opossums were infected by T. cruzi, which presented lymphocytosis (3.4 ± 1.5) and eosinophilia (0.09 ± 0.13). Path analysis showed that T. cruzi infection resulted in increased numbers of lymphocytes and indirectly decreased the body condition of opossums. Moreover T. cruzi infection resulted in a direct effect on decrease of MCV. Overall, our results suggest that T. cruzi infection may represent a risk to health of opossums since the lymphocytosis may cause a secondary damage on body condition of infected animals.

Outcomes of Trypanosoma cruzi and Trypanosoma evansi infections on health of Southern coati (Nasua nasua), crab-eating fox (Cerdocyon thous), and ocelot (Leopardus pardalis) in the Brazilian Pantanal

The occurrence of Trypanosoma spp. in wild carnivore populations has been intensively investigated during the last decades. However, the impact of these parasites on the health of free-living infected animals has been largely neglected. The Pantanal biome is the world’s largest seasonal wetland, harboring a great diversity of species and habitats. This includes 174 species of mammals, of which 20 belong to the order Carnivora. The present study aimed to investigate the effect of Trypanosoma evansi and Trypanosoma cruzi infections and coinfections on the health of the most abundant carnivores in the Pantanal: coati (Nasua nasua), crab-eating fox (Cerdocyon thous), and ocelot (Leopardus pardalis). We captured 39 coatis, 48 crab-eating foxes, and 19 ocelots. Diagnostic tests showed T. cruzi infection in 7 crab-eating foxes and 5 coatis. Additionally, 7 crab-eating foxes, 10 coatis, and 12 ocelots were positive for T. evansi. We observed coinfections in 9 crab-eating foxes, 8 coatis, and 2 ocelots. This is the first report of T. evansi and T. cruzi infection on the health of free-living ocelots and crab-eating foxes. We showed that single T. evansi or T. cruzi infection, as well as coinfection, caused some degree of anemia in all animals, as well as an indirect negative effect on body condition in coatis and crab-eating foxes via anemia indicators and immune investment, respectively. Furthermore, the vigorous immune investment observed in sampled coatis, crab-eating foxes and ocelots infected by T. evansi, T. cruzi and coinfected can be highly harmful to their health. Overall, our results indicate that single and combined infection with T. evansi and T. cruzi represent a severe risk to the health of wild carnivores in the Pantanal region.

Parasitemia in a neonatal bison calf

A 3-day old female bison calf (Bison bison) was presented in lateral recumbency to the Université de Montréal Veterinary Teaching Hospital. The animal was severely depressed and dehydrated (10%) and died a few hours after admission. Prior to death, blood samples were obtained for CBC, clinical chemistry, and serology tests. Abnormal CBC findings included thrombocytopenia, lymphocytosis, mild monocytosis, and a toxic left shift. Abnormal serum clinical chemistry findings included marked azotemia, hyperphosphatemia, hypernatremia, hyperalbuminemia, hypoglobulinemia, and low gamma-glutamyltransferase activity. Serologic test results for bovine leukosis virus and bovine viral diarrhea virus were negative. Blood smear examination revealed numerous elongated organisms that were tapered at both ends and characterized by an undulating membrane and a long flagellum. The organisms ranged in length from 35 to 40 micro meter, excluding the flagellum, and were identified as Trypanosoma theileri. Postmortem examination revealed that the animal suffered from concurrent mycotic abomasitis and colisepticemia.

Options for field diagnosis of human african trypanosomiasis

Human African trypanosomiasis (HAT) due to Trypanosoma brucei gambiense or T. b. rhodesiense remains highly prevalent in several rural areas of sub-Saharan Africa and is lethal if left untreated. Therefore, accurate tools are absolutely required for field diagnosis. For T. b. gambiense HAT, highly sensitive tests are available for serological screening but the sensitivity of parasitological confirmatory tests remains insufficient and needs to be improved. Screening for T. b. rhodesiense infection still relies on clinical features in the absence of serological tests available for field use. Ongoing research is opening perspectives for a new generation of field diagnostics. Also essential for both forms of HAT is accurate determination of the disease stage because of the high toxicity of melarsoprol, the drug most widely used during the neurological stage of the illness. Recent studies have confirmed the high accuracy of raised immunoglobulin M levels in the cerebrospinal fluid for the staging of T. b. gambiense HAT, and a promising simple assay (LATEX/IgM) is being tested in the field. Apart from the urgent need for better tools for the field diagnosis of this neglected disease, improved access to diagnosis and treatment for the population at risk remains the greatest challenge for the coming years.

Glomerulopathy associated with parasitic infections

Although parasitic infections do not usually present with disturbance in renal function, glomerular lesions can be seen in most of these infections. The glomerular lesions observed in parasitic infections cover the whole range of glomerular lesions known, but most of them are proliferative. Little is known of the exact pathogenic mechanisms. In this review, we try to explain the glomerular lesions associated with parasitic infections in terms of the specific immunologic events observed during these diseases against the background of recent developments in the general knowledge of the pathogenesis of glomerular disease.

Glomerulopathy associated with parasitic infections

Although parasitic infections do not usually present with disturbance in renal function, glomerular lesions can be seen in most of these infections. The glomerular lesions observed in parasitic infections cover the whole range of glomerular lesions known, but most of them are proliferative. Little is known of the exact pathogenic mechanisms. In this review, we try to explain the glomerular lesions associated with parasitic infections in terms of the specific immunologic events observed during these diseases against the background of recent developments in the general knowledge of the pathogenesis of glomerular disease.

Detection of antibodies to platelets and erythrocytes during infection with haemorrhage-causing Trypanosoma vivax in Ayrshire cattle

Ayrshire cattle, which were infected with a stock of Trypanosoma vivax from Galana, Kenya, which produced haemorrhagic disease, were examined for the presence of antibodies to erythrocytes and platelets. Antibodies to normal erythrocytes and platelets were detected in the plasma of infected animals using the enzyme-linked immunosorbent assay (ELISA). The antibodies were detectable following the first peak of parasitaemia (10-15 days after infection) and antibody activity was maximal 30-35 days after infection. Plasma from cattle, taken 32 days after infection, precipitated radiolabelled proteins from autologous platelets and, less efficiently, from autologous erythrocytes. Fluorescence-activated cell sorter (FACS) assays demonstrated that erythrocytes and platelets from infected cattle bound IgM and IgG in vivo, and that both normal blood cell types could adsorb these antibodies following incubation in plasma from infected animals. Complement (C3) was similarly adsorbed to erythrocytes during infection. Antibodies adsorbed to infected erythrocytes could be eluted and the eluted antibodies bound to normal erythrocytes, as detected by immunofluorescence, but they did not react with the infecting trypanosome. It is hypothesised that although anti-blood cell antibodies may not be the primary cause of the severe anaemia and thrombocytopaenia which accompany the haemorrhagic syndrome, they could play an important role in the maintenance of these signs of disease, adversely affecting the outcome of T. vivax-associated haemorrhagic disease in the field.

Macrophage procoagulant activity in experimental African trypanosomiasis

Peritoneal macrophages from mice infected with Trypanosoma brucei brucei expressed a greatly elevated procoagulant activity (PCA) which could be reversed to normal levels after trypanocidal therapy. Comparison with infection caused by the non-pathogenic T. musculi suggested that the level of PCA related to parasite pathogenicity. Unstimulated macrophages, which generate only slight PCA upon stimulation with zymosan, become hyperresponsive to this stimulus during the course of infection. Hyperresponsiveness is not a generalized feature of these cells during infection, as they become progressively hyporesponsive to the same stimulus in terms of lysosomal enzyme secretion. We were unable to demonstrate a direct role of the trypanosomes in macrophage activation; however, artificial removal of the glycoprotein coat rendered the parasites highly stimulatory for macrophages even in the absence of opsonins. These results suggest that the parasites may activate macrophages indirectly, and that the resulting elevated PCA may play a role in the abnormal blood coagulation known to occur in this disease.

The pathogenesis of sleeping sickness

Although the clinical and pathological features of sleeping sickness have been well recognized since the beginning of the century, we still have very little idea about how these changes are brought about. A convincing role for a trypanosome-derived toxin has yet to be established and it is probable that most tissue damage results from an immunopathological reaction. An immediate type hypersensitivity reaction might account for the pruritus and urticaria sometimes encountered in patients with the infection. Autoantibodies are produced by patients with sleeping sickness but it has not been established that these can cause tissue damage. Similarly, although high levels of immune complexes are found in patients with sleeping sickness, it has yet to be clearly established that these damage the brain or heart. The dominant pathological event in sleeping sickness is B lymphocyte proliferation, first within the lymph nodes and then within the brain and meninges, and this response may lead to tissue damage in some way which has not yet been identified. B lymphocyte proliferation could result from the action of a trypanosome-derived mitogen or from interference with T lymphocyte control over B lymphocyte function.

The advantage of a build-up anti-globulin technique for the detection of immunoglobulin on the red cells of rabbits infected with trypanosomes. A preliminary report

A build-up anti-globulin technique has been used to detect immunoglobulin on the red cells of rabbits infected with Trypanosoma brucei brucei S 42 and 427. The method, which is useful for the detection of immunoglobulin on sparsely coated red cells, involves treating the red cells of infected rabbits with antiglobulin followed by alternate globulin and antiglobulin layers until a lattice is built up which allows agglutination to occur. The red cells of five infected rabbits have been tested with anti-rabbit IgG,-IgM and broad spectrum anti-globulin reagents at intervals after infection and following the administration of Berenil, a drug which destroys trypanosomes. The positive anti-globulin reactions which developed following inoculation with trypanosomes were much reduced after giving Berenil. The tests became more strongly positive again in two rabbits after reinfection.

Fibrinogen and fibrinogen/fibrin degradation products in the urine of rabbits infected with Trypanosoma (trypanozoon) brucei

Studies have been carried out on the urine of rabbits infected with Trypanosoma (Trypanozoon) brucei to determine whether fibrinogen or fibrinogen/fibrin degradation products (FDP) could be detected. No fibrinogen was found but during the last two weeks of this 7-week infection low levels of FDP were present in the urine which did not exceed 5 microgram/ml. Rabbit urine was shown to contain a potent proteolytic enzyme capable of breaking down rabbit fibrinogen and both early and late FDP were present in the cleavage products. No deposits of fibrin were detected in the kidney, but casts were present in the urine suggesting renal damage. The most likely explanation of the urinary FDP is that either an increase in the glomerular permeability occurs allowing filtration of plasma FDP or a local fibrinogenolysis in the kidney tubules.

Thrombocytopenia in experimental trypanosomiasis

The effect of experimental trypanosomiasis on coagulation was studied because a patient in this hospital with Rhodesian trypanosomiasis developed thrombocytopenia with disseminated intravascular coagulation. Rats injected intraperitoneally with this strain of Trypanosoma rhodesiense consistently developed trypanosomiasis and severe thrombocytopenia without changes in hematocrit or concentration of fibrinogen or fibrin split products. At the time of 50% mortality (4-5 days) mean platelet counts per cubic millimeter of infected rats were 18,000+/-9,000 (+/-2 SEM) compared to 1,091,000+/-128,000 in uninfected controls. In vitro, concentrated trypanosomes and trypanosomefree supernates of disrupted organisms added to normal rat, rabbit, or human blood produced platelet aggregation within 30 min. This platelet aggregation was not blocked by inhibitors of ADP, kinins, or early or late components of complement. In vivo thrombocytopenia also occurred in infected rabbits congenitally deficient in C6 and in infected, splenectomized rats. Although the aggregating substance obtained from disrupted trypanosomes is heat-labile, it is active in the presence of complement inhibitors, suggesting that this trypanosomal product may be a protein enzyme or toxin. Since the phenomenon is independent of immune complexes, complement, ADP, and kinins, it appears to represent a new mechanism of microbial injury of platelets and the induction of thrombocytopenia.