Plasmodium falciparum transcription in different clinical presentations of malaria associates with circulation time of infected erythrocytes.

Following Plasmodium falciparum infection, individuals can remain asymptomatic, present with mild fever in uncomplicated malaria cases, or show one or more severe malaria symptoms. Several studies have investigated associations between parasite transcription and clinical severity, but no broad conclusions have yet been drawn. Here, we apply a series of bioinformatic approaches based on P. falciparum's tightly regulated transcriptional pattern during its ~48-hour intraerythrocytic developmental cycle (IDC) to publicly available transcriptomes of parasites obtained from malaria cases of differing clinical severity across multiple studies. Our analysis shows that within each IDC, the circulation time of infected erythrocytes without sequestering to endothelial cells decreases with increasing parasitaemia or disease severity. Accordingly, we find that the size of circulating infected erythrocytes is inversely related to parasite density and disease severity. We propose that enhanced adhesiveness of infected erythrocytes leads to a rapid increase in parasite burden, promoting higher parasitaemia and increased disease severity.

CCL3/Macrophage Inflammatory Protein-1α Is Dually Involved in Parasite Persistence and Induction of a TNF- and IFNγ-Enriched Inflammatory Milieu in Trypanosoma cruzi-Induced Chronic Cardiomyopathy.

CCL3, a member of the CC-chemokine family, has been associated with macrophage recruitment to heart tissue and parasite control in the acute infection of mouse with Trypanosoma cruzi, the causative agent of Chagas disease. Here, we approached the participation of CCL3 in chronic chagasic cardiomyopathy (CCC), the main clinical form of Chagas disease. We induced CCC in C57BL/6 (ccl3+/+) and CCL3-deficient (ccl3-/-) mice by infection with the Colombian Type I strain. In ccl3+/+ mice, high levels of CCL3 mRNA and protein were detected in the heart tissue during the acute and chronic infection. Survival was not affected by CCL3 deficiency. In comparison with ccl3+/+, chronically infected ccl3-/- mice presented reduced cardiac parasitism and inflammation due to CD8+ cells and macrophages. Leukocytosis was decreased in infected ccl3-/- mice, paralleling the accumulation of CD8+ T cells devoid of activated CCR5+ LFA-1+ cells in the spleen. Further, T. cruzi-infected ccl3-/-mice presented reduced frequency of interferon-gamma (IFNγ)+ cells and numbers of parasite-specific IFNγ-producing cells, while the T. cruzi antigen-specific cytotoxic activity was increased. Stimulation of CCL3-deficient macrophages with IFNγ improved parasite control, in a milieu with reduced nitric oxide (NOx) and tumor necrosis factor (TNF), but similar interleukin-10 (IL-10), concentrations. In comparison with chronically T. cruzi-infected ccl3+/+ counterparts, ccl3-/- mice did not show enlarged heart, loss of left ventricular ejection fraction, QTc prolongation and elevated CK-MB activity. Compared with ccl3+/+, infected ccl3-/- mice showed reduced concentrations of TNF, while IL-10 levels were not affected, in the heart milieu. In spleen of ccl3+/+ NI controls, most of the CD8+ T-cells expressing the CCL3 receptors CCR1 or CCR5 were IL-10+, while in infected mice these cells were mainly TNF+. Lastly, selective blockage of CCR1/CCR5 (Met-RANTES therapy) in chronically infected ccl3+/+ mice reversed pivotal electrical abnormalities (bradycardia, prolonged PR, and QTc interval), in correlation with reduced TNF and, mainly, CCL3 levels in the heart tissue. Therefore, in the chronic T. cruzi infection CCL3 takes part in parasite persistence and contributes to form a CD8+ T-cell and macrophage-enriched cardiac inflammation. Further, increased levels of CCL3 create a scenario with abundant IFNγ and TNF, associated with cardiomyocyte injury, heart dysfunction and QTc prolongation, biomarkers of severity of Chagas' heart disease.

Effects of malaria parasitaemia on some haemostatic parameters among pregnant women of African descent in Specialist Hospital Sokoto, Nigeria.

BACKGROUND: Malaria in pregnancy is a major contributor to adverse maternal and prenatal outcome. In hyper endemic areas like ours, it is a common cause of anaemia in pregnancy and is aggravated by poor socioeconomic circumstance. This study evaluated the prothrombin time and activated partial thromboplastin time of malaria parasitized pregnant women. METHOD: A total of 90 pregnant women participated in the study, 60 of which were malaria positive and 30 of which were malaria negative. Participants were recruited from the antenatal Clinic of Specialist Hospital Sokoto, Nigeria. A structured interviewer-administered questionnaire was used to obtain some socio-demographic characteristics of subjects. Blood samples were collected in ethylene diamine tetra acetic acid and examined for malaria parasite and platelet count while citrated samples were used for the determination of some haemostatic parameters (prothrombin time and activated partial thromboplastin time). Data generated was analyzed using SPSS 25.0 statistical package. A p-value ⩽ 0.05 was considered significant in all statistical comparisons. RESULT: There was a statistically significant decrease (p= 0.000) in the platelet counts of the parasitized subjects compared to the non-parasitized controls. We observed a significant prolongation on both the prothrombin time and activated partial thromboplastin time among the parasitized subjects compared to the non-parasitized controls (p= 0.000). CONCLUSION: This study has shown that malaria in pregnancy causes a significant decrease in the platelet count and prolongation in the prothrombin (PT) and the activated partial thromboplastin time (APTT). There is need for the malaria and haemostatic parameters to be assayed routinely on pregnant women particularly those presenting to antenatal clinic with febrile illness.

Characteristics of Subpatent Malaria in a Pre-Elimination Setting in Southern Zambia.

To achieve and sustain malaria elimination, identification and treatment of the asymptomatic infectious reservoir is critical. Malaria rapid diagnostic tests (RDTs) are frequently used to identify asymptomatic, Plasmodium-infected individuals through test-and-treat strategies, but their sensitivity is low when used in low transmission settings. Characteristics of individuals with subpatent (RDT-negative but polymerase chain reaction [PCR]-positive) Plasmodium parasitemia were evaluated in southern Zambia where malaria transmission has declined and efforts to achieve malaria elimination are underway. Simple random sampling based on satellite imagery was used to select households for participation in community-based, cross-sectional surveys between 2008 and 2013. Questionnaires were administered to collect information on age, gender, recent history of malaria symptoms, and recent antimalarial drug use. Blood samples were collected by finger prick for Plasmodium falciparum histidine-rich protein 2 RDT, blood smears for microscopy, and dried blood spots for molecular analysis to detect malaria parasites and their sexual stage. Of 3,863 participants with complete data, 102 (2.6%) were positive by microscopy, RDT, or PCR. Of these, 48 (47%) had subpatent parasitemia. Most individuals with subpatent parasitemia were asymptomatic (85%). Compared with individuals without parasitemia, individuals with subpatent parasitemia were significantly more likely to be aged 5-25 years. Approximately one quarter (27%) of those with subpatent parasitemia had detectable gametocytemia. These findings suggest that strategies based on active or reactive case detection can identify asymptomatic individuals positive by RDT, but more sensitive diagnostic tests or focal drug administration may be necessary to target individuals with subpatent parasitemia to achieve malaria elimination.

Eryptosis of non-parasitized erythrocytes is related to anemia in Plasmodium berghei low parasitema malaria of Wistar rats.

It is known that premature elimination of non-parasitized RBCs (nRBCs) plays an important role in the pathogenesis of malarial anemia, in which suicidal death process (eryptosis) of nRBCs has been suggested to be involved. To check this possibility, we investigate eryptosis during infection of P. berghei ANKA in Wistar rats, a malaria experimental model that, similar to human malaria, the infection courses with low parasitemia and acute anemia. As expected, P. berghei ANKA infection was marked by low parasite burdens that reached a mean peak of 3% between days six and nine post-infection and solved spontaneously. A significant reduction of the hemoglobin levels (~ 30%) was also observed on days subsequent to the peak of parasitemia, persisting until day 16 post-infection. In eryptosis assays, it was observed a significant increase in the levels of PS-exposing nRBC, which coincided with the reduction of hemoglobin levels and was positively related to anemia. In addition to PS externalization, eryptosis of nRBC induced by P. berghei infection was characterized by cytoplasm calcium influx, but not caspases activity. These results confirm our previous studies evidencing a pro-eryptotic effect of malaria infection on nRBCs and show that a caspase-independent eryptotic process is implicated in anemia induced by P. berghei ANKA infection in Wistar rats.

Low intensity blood parasite infections do not reduce the aerobic performance of migratory birds.

Blood parasites (Haemosporidia) are thought to impair the flight performance of infected animals, and therefore, infected birds are expected to differ from their non-infected counterparts in migratory capacity. Since haemosporidians invade host erythrocytes, it is commonly assumed that infected individuals will have compromised aerobic capacity, but this has not been examined in free-living birds. We tested if haemosporidian infections affect aerobic performance by examining metabolic rates and exercise endurance in migratory great reed warblers (Acrocephalus arundinaceus) experimentally treated with Plasmodium relictum pGRW04 and in naturally infected wild birds over consecutive life-history stages. We found no effect of acute or chronic infections on resting metabolic rate, maximum metabolic rate or exercise endurance in either experimentally treated or free-living birds. Oxygen consumption rates during rest and while undergoing maximum exercise as well as exercise endurance increased from breeding to migration stages in both infected and non-infected birds. Importantly, phenotypic changes associated with preparation for migration were similarly unaffected by parasitaemia. Consequently, migratory birds experiencing parasitaemia levels typical of chronic infection do not differ in migratory capacity from their uninfected counterparts. Thus, if infected hosts differ from uninfected conspecifics in migration phenology, other mechanisms besides aerobic capacity should be considered.

An experimental test of the physiological consequences of avian malaria infection.

Chronic, low-intensity parasite infections can reduce host fitness through negative impacts on reproduction and survival, even if they produce few overt symptoms. As a result, these parasites can influence the evolution of host morphology, behaviour and physiology. The physiological consequences of chronic infection can provide insight into the processes underlying parasite-driven natural selection. Here, we evaluate the physiological consequences of natural, low-intensity infection in an avian host-parasite system: adult male red-winged blackbirds (Agelaius phoeniceus) infected with haemosporidian parasites. Chronic haemosporidian infection has previously been shown to reduce both reproductive success and survival in several avian species. We used antimalarial medications to experimentally reduce haemosporidian parasitaemia (the proportion of blood cells infected with haemosporidian parasites) and measured the effect of treatment on body condition, haematology, immune function, physiological stress and oxidative state. Treatment with an antimalarial medication reduced parasitaemia for the most prevalent haemosporidian parasites from the genus Plasmodium. Treatment also increased haemoglobin and haematocrit, and decreased red blood cell production rates. We detected no effect of treatment on body condition, immune metrics, plasma corticosterone concentrations, total antioxidant capacity or reactive oxygen metabolites. Our results suggest that the damage and replacement of red blood cells during infection could be important costs of chronic haemosporidian infection. Strong links between parasitaemia and the physiological consequences of infection indicate that even for relatively low-intensity infections, measuring parasitaemia rather than only presence/absence could be important when evaluating the role of infection in influencing hosts' behaviour, physiology or fitness.

Influence of environmental enrichment on the behavior and physiology of mice infected by Trypanosoma cruzi.

INTRODUCTION:: Enriched environments normally increase behavioral repertoires and diminish the expression of abnormal behaviors and stress-related physiological problems in animals. Although it has been shown that experimental animals infected with microorganisms can modify their behaviors and physiology, few studies have evaluated how environmental enrichment affects these parameters. This study aimed to evaluate the effects of environmental enrichment on the behavior and physiology of confined mice infected with Trypanosoma cruzi. METHODS:: The behaviors of 20 T. cruzi-infected mice and 20 non-infected mice were recorded during three treatments: baseline, enrichment, and post-enrichment. Behavioral data were collected using scan sampling with instantaneous recording of behavior every 30s, totaling 360h. Plasma TNF, CCL2, and IL-10 levels and parasitemia were also evaluated in infected enriched/non-enriched mice. Behavioral data were evaluated by Friedman's test and physiological data by one-way ANOVA and area under the curve (AUC) analysis. RESULTS:: Results showed that environmental enrichment significantly increased exploratory behaviors and diminished inactivity. The use of environmental enrichment did not diminish circulating levels of TNF and IL-10 but diminished circulating levels of CCL2 and parasitemia. CONCLUSIONS:: Positive behavioral and physiological effects of environmental enrichment were observed in mice living in enriched cages. Thus, environmental enrichment improved the welfare of these animals.

Influence of environmental enrichment on the behavior and physiology of mice infected by trypanosoma cruzi

Abstract INTRODUCTION: Enriched environments normally increase behavioral repertoires and diminish the expression of abnormal behaviors and stress-related physiological problems in animals. Although it has been shown that experimental animals infected with microorganisms can modify their behaviors and physiology, few studies have evaluated how environmental enrichment affects these parameters. This study aimed to evaluate the effects of environmental enrichment on the behavior and physiology of confined mice infected with Trypanosoma cruzi. METHODS: The behaviors of 20 T. cruzi-infected mice and 20 non-infected mice were recorded during three treatments: baseline, enrichment, and post-enrichment. Behavioral data were collected using scan sampling with instantaneous recording of behavior every 30s, totaling 360h. Plasma TNF, CCL2, and IL-10 levels and parasitemia were also evaluated in infected enriched/non-enriched mice. Behavioral data were evaluated by Friedman's test and physiological data by one-way ANOVA and area under the curve (AUC) analysis. RESULTS: Results showed that environmental enrichment significantly increased exploratory behaviors and diminished inactivity. The use of environmental enrichment did not diminish circulating levels of TNF and IL-10 but diminished circulating levels of CCL2 and parasitemia. CONCLUSIONS: Positive behavioral and physiological effects of environmental enrichment were observed in mice living in enriched cages. Thus, environmental enrichment improved the welfare of these animals.

Assessing the impact of differences in malaria transmission intensity on clinical and haematological indices in children with malaria.

BACKGROUND: Malaria control interventions have led to a decline in transmission intensity in many endemic areas, and resulted in elimination in some areas. This decline, however, will lead to delayed acquisition of protective immunity and thus impact disease manifestation and outcomes. Therefore, the variation in clinical and haematological parameters in children with malaria was assessed across three areas in Ghana with varying transmission intensities. METHODS: A total of 568 children between the ages of 2 and 14 years with confirmed malaria were recruited in hospitals in three areas with varying transmission intensities (Kintampo > Navrongo > Accra) and a comprehensive analysis of parasitological, clinical, haematological and socio-economic parameters was performed. RESULTS: Areas of lower malaria transmission tended to have lower disease severity in children with malaria, characterized by lower parasitaemias and higher haemoglobin levels. In addition, total white cell counts and percent lymphocytes decreased with decreasing transmission intensity. The heterozygous sickle haemoglobin genotype was protective against disease severity in Kintampo (P = 0.016), although this was not significant in Accra and Navrongo. Parasitaemia levels were not a significant predictor of haemoglobin level after controlling for age and gender. However, higher haemoglobin levels in children were associated with certain socioeconomic factors, such as having fathers who had any type of employment (P < 0.05) and mothers who were teachers (P < 0.05). CONCLUSIONS: The findings demonstrate significant differences in the haematological presentation and severity of malaria among areas with different transmission intensity in Ghana, indicating that these factors need to be considered in planning the management of the disease as the endemicity is expected to decline after control interventions.

Role of LRV1 and RNAi in the Pathogenesis of Leishmania.

The recent paper by Brettmann et al. provides insight as to how an RNA virus can persistently coexist in a protozoan with RNAi activity and how these two entities work to maintain balance. The authors were also able to successfully remove the virus and examine the role of the virus in parasitemia and the pathogenesis of leishmaniasis.

The Strategy to Survive Primary Malaria Infection: An Experimental Study on Behavioural Changes in Parasitized Birds.

Avian malaria parasites (Haemosporida, Plasmodium) are of cosmopolitan distribution, and they have a significant impact on vertebrate host fitness. Experimental studies show that high parasitemia often develops during primary malaria infections. However, field studies only occasionally reveal high parasitemia in free-living birds sampled using the traditional methods of mist-netting or trapping, and light chronic infections predominate. The reason for this discrepancy between field observation and experimental data remains insufficiently understood. Since mist-netting is a passive capture method, two main parameters determine its success in sampling infected birds in wildlife, i. e. the presence of parasitized birds at a study site and their mobility. In other words, the trapping probability depends on the survival rate of birds and their locomotor activity during infection. Here we test (1) the mortality rate of wild birds infected with Plasmodium relictum (the lineage pSGS1), (2) the changes in their behaviour during presence of an aerial predator, and (3) the changes in their locomotor activity at the stage of high primary parasitemia.We show that some behavioural features which might affect a bird's survival during a predator attack (time of reaction, speed of flush flight and take off angle) did not change significantly during primary infection. However, the locomotor activity of infected birds was almost halved compared to control (non-infected) birds during the peak of parasitemia. We report (1) the markedly reduced mobility and (2) the 20% mortality rate caused by P. relictum and conclude that these factors are responsible for the underrepresentation of birds in mist nets and traps during the stage of high primary parasitemia in wildlife. This study indicates that the widespread parasite, P. relictum (pSGS1) influences the behaviour of birds during primary parasitemia. Experimental studies combined with field observations are needed to better understand the mechanisms of pathogenicity of avian malaria parasites and their influence on bird populations.

Bacillus Calmette-Guérin-inoculation at different time points influences the outcome of C57BL/6 mice infected with Plasmodium chabaudi chabaudi AS.

Bacillus Calmette-Guérin (BCG) is an attenuated Mycobacterium tuberculosis vaccine. We performed a series of co-infection experiments with BCG-Plasmodium chabaudi chabaudi Landau, 1965 AS using C57BL/6 mice to analyse whether BCG can affect the development of protective immunity to infection with Plasmodium spp. and the mechanism of this protection. We divided mice into four groups: BCG-inoculation 4 weeks prior to P. c. chabaudi AS infection (B-4w-Pc); simultaneous BCG-inoculation and P. c. chabaudi AS infection (Pc+B); BCG-inoculation 3 days post P. c. chabaudi AS (Pc-3-B) infection; and mono-P. c. chabaudi AS infection as control (Pc). The parasitemia level in the B-4w-Pc group was noticeably higher than control group at 6-19 days post infection (dpi). Compared with the control group, the proportion of CD4(+)CD69(+) T cells was significantly reduced 5, 8 and 12 dpi, but the proportion of CD4(+)CD25(+)Foxp3(+) Tregs was significantly increased in the B-4w-Pc group on 5 and 8 dpi. The B-4w-Pc group also demonstrated reduced levels of IFN-γ and TNF-α on 5 and 8 dpi and significantly elevated level of IL-10 on 12 dpi. There were significantly fewer mDCs (CD11c(+)CD11b(+)) and pDCs (CD11c(+)B220(+)) in the B-4w-Pc group than the control group at all the time points post infection and the expression of MHC II was noticeably reduced on day 8 pi. Our findings confirmed that BCG inoculation prior to Plasmodium infection resulted in excessive activation and proliferation of Tregs and upregulation of anti-inflammatory mediators, which inhibited establishment of a Th1-dominant immune response during the early stages of Plasmodium infection by inhibiting dendritive cells response. BCG inoculation prior to P. c. chabaudi AS infection may contribute to overgrowth of parasites as well as mortality in mice.

Cytokine modulation of human blood viscosity from vivax malaria patients.

Malaria is a major infectious disease in several countries and is caused by protozoa of the genus Plasmodium. In vivax malaria patients, inflammatory processes occur, as well as changes in cytokines and blood flow. The present study analyzed the cytokine modulation of blood viscosity from patients infected with Plasmodium vivax (P. vivax). Blood samples were collected from 42 non-infected individuals (control group) and 37 individuals infected with P. vivax. The IL-2, IL-4, IL-6, IL-10, TNFα, TGF-ß and IL-17 cytokine concentrations in the serum were assessed, and the blood rheological properties were determined. The analysis of blood viscosity for shear rates revealed that the blood viscosity of the infected patients was significantly greater than that of the non-infected individuals. The viscosity of the blood was greater in the infected individuals than in the non-infected subjects. The serum from individuals with P. vivax infections exhibited higher IFN-γ and IL-17 concentrations and lower TGF-ß levels. Incubation of the blood from infected individuals with IL-17 or IL-17 associated with IFN-γ reduced the viscosity to rates equivalent to the blood from non-infected individuals. Independently of cytokine modulation, no correlation was found between the parasitemia and blood viscosity of the infected patients. These data suggest that the alterations of blood viscosity are relevant as an auxiliary tool for the clinical diagnosis of disease. In malaria, erythrocytes are more sensitive to osmotic shock, and the reduction of viscosity by IL-17 may be related to a possible immunomodulator agent during infection.

Co-infection with Plasmodium berghei and Trypanosoma brucei increases severity of malaria and trypanosomiasis in mice.

Individuals in natural populations may be infected with multiple different parasites at a time. These parasites may interact with each other or act independently in the host, and this may result to varying outcomes on host health and survival. This study therefore aimed at investigating the health impact of co-infection of mice with Plasmodium berghei and Trypanosoma brucei. Forty Swiss albino mice (14-17g) were divided into four groups of ten. Mice in groups A and B received 10(6)P. berghei and groups B and C 10(5)T. brucei, while group D were uninfected. The co-infected mice had higher P. berghei and T. brucei parasitaemia, compared with the mono-infected mice. The co-infected mice had significantly (p<0.05) lower survival rate compared with the mono-infected mice. Co-infection of mice with P. berghei and T. brucei resulted in rapid P. berghei and T. brucei development and increased parasitaemia. The leukocyte numbers significantly (p<0.05) reduced on days 12 and 15 post infection among P. berghei infected mice, in the presence or absence of T. brucei. Anaemia and hypoglycaemia was more severe in the co-infected mice. Therefore, co-infection of mice with P. berghei and T. brucei may increase pathologic impact to the host by increasing parasitaemia.

ASIATIC ACID INFLUENCES GLUCOSE HOMEOSTASIS IN P. BERGHEI MURINE MALARIA INFECTED SPRAGUE-DAWLEY RATS.

BACKGROUND: Glucose homeostasis derangement is a common pathophysiology of malaria whose aetiology is still controversial. The Plasmodium parasite, immunological and inflammatory responses, as well as chemotherapeutics currently used cause hypoglycaemia in malaria. Anti-parasitic and anti-disease drugs are required to combat malaria while ameliorating the pathophysiology of the infection. Asiatic acid has anti-hyperglycaemic, antioxidant, pro-oxidant properties useful in glucose homeostasis but its influence in malaria is yet to be reported. Here we present findings on the influence of asiatic acid on glucose metabolism in vivo using P. berghei-infected Sprague Dawley rats. MATERIALS AND METHODS: Acute as well as sub-chronic studies were carried out in vivo where physicochemical properties and glucose homeostasis were monitored after administration of asiatic acid (10mg/kg) in both non-infected and infected animals. Glucose metabolism associated biochemical changes in malaria were also investigated. RESULTS: In acute studies, asiatic acid improved oral glucose response while in the sub-chronic state it maintained food and water intake and suppressed parasitaemia. Normoglycaemic control was maintained in infected animals through insulin suppression and increasing glucagon secretion, in both acute and chronic studies. Asiatic acid administration curtailed lactate concentration towards normal. CONCLUSION: Per oral post-infection asiatic acid administration preserved drinking and eating habits, inhibited sickness behaviour while suppressing parasitaemia. Reciprocal relationship between insulin and glucagon concentrations was maintained influencing glucose homeostasis positively and inhibition of hyperlactaemia in malaria. Abbreviations: ip -intraperitoneal, po -per oral, ig -intragastric, AA-Asciatic acid, OGTT-oral glucose tolerance test, OS-oxidative stress, ROS-reactive oxygen species, NO-nitric oxide, ONOO- - peroxynitrite, BRU-Biomedical Research Unit, SD-Sprague Dawley.

Comparative clinico-haematological analysis in young Zebu cattle experimentally infected with Trypanosoma vivax isolates from tsetse infested and non-tsetse infested areas of Northwest Ethiopia.

BACKGROUND: Ethiopia, particularly in the Northwest region, is affected by both tsetse and non-tsetse fly transmitted trypanosomosis, with significant impact on livestock productivity. The aim of this study was to determine and compare clinical findings and haematological values between experimental infections induced by Trypanosoma vivax isolates from areas of either transmission mode. Sixteen young (aged between 6 and 12 months) Zebu cattle (Bos indicus), purchased from a trypanosome-free area and confirmed to be trypanosome-negative, were randomly assigned into four groups of four animals. Groups 1, 2 and 3 were infected with an isolate from a tsetse infested or one of two isolates from a non-tsetse infested area, and group 4 was a non-infected control. All animals in the infected groups were inoculated intravenously with 2 × 10(6) trypanosomes from donor animals. The experimental animals were monitored for eight consecutive weeks post infection for clinical signs, parasitaemia and haematological changes in packed cell volume (PCV), haemoglobin concentration (Hgb), total red blood cell (RBC) and white blood cell (WBC) counts, differential WBC count and blood indices (mean corpuscular volume [MCV], mean corpuscular haemoglobin and mean corpuscular haemoglobin concentration). RESULTS: Infection was characterized by reduced feed intake, weakness, pyrexia, parasitaemia, rough hair coat, enlarged prescapular lymph nodes, lacrimation, weight loss, pallor mucus membrane and dehydration. Body weight loss in all infected groups was significantly higher than in the non-infected control. Similarly, body weight loss was higher (P < 0.001) in animals infected with the tsetse infested isolate than with the non-tsetse infested isolates. The mean PCV, Hgb, total RBC and WBC counts were lower (P < 0.001), and mean MCV was higher (P = 0.01) in all infected groups than in non-infected control animals at different time points during the study period. Except for minor variations in haematological values, the overall changes were similar in all infected groups. CONCLUSION: Clinical signs and significant reduction in haematological values in the infected groups indicated the pathogenicity of the T. vivax parasites. Pathogenicity of T. vivax from the non-tsetse infested area can be considered as nearly as important as that of its counterpart derived from the tsetse infested area.

Effect of chronic khat (Catha edulis, Forsk) use on outcome of Plasmodium berghei ANKA infection in Swiss albino mice.

BACKGROUND: The objective of this study was to explore effects of khat (Catha edulis) on outcome of rodent malaria infection and its anti-plasmodial activities on Plasmodium berghei ANKA (PbA). METHODS: Female Swiss albino mice were orally treated with crude khat (Catha edulis) extracts (100, 200 and 300 mg/kg) on a daily basis for 4 weeks prior to PbA infection. Physical, clinical, hematological, biochemical and histo-pathological features of the mice were assessed. In addition, in vivo anti-plasmodial activities of khat were evaluated. RESULTS: The finding of this study showed that khat use was strongly associated with increment of levels of liver and kidney biomarkers, leucopenia, severe anemia, rise in level of inflammation biomarkers: C-reactive protein (CRP), uric acid (UA), increased monocyte-lymphocyte count ratio (MLCR), manifestation of cerebral malaria symptoms such as ataxia, paralysis and deviation of the head but with no pulmonary edema. Significantly lower level of parasitemia (P<0.05), rectal temperature, but, high level of hemoglobin were observed at the early stage of the PbA infection in khat treated mice than the control. With extension of the treatment period, however, drastic increments were observed in parasite load and rectal temperature although there was reduction in hemoglobin (Hb) level. Moreover, khat showed poor anti-plasmodial activity with <10% parasite suppression activity and lack protection against major malaria symptoms. The significant reduction (P<0.01) of hematological parameters during PbA infection strengthen the notion that hematological parameters could be good predictors of severe malaria complications in human. CONCLUSIONS: In mice model treated with khat prior to infection with the rodent malaria parasite, khat was found to worsen manifestation of most malaria complications. Furthermore, the same plant showed poor in vivo anti-plasmodial activity and protection against major malaria symptoms.

Development of a pHrodo-based assay for the assessment of in vitro and in vivo erythrophagocytosis during experimental trypanosomosis.

Extracellular trypanosomes can cause a wide range of diseases and pathological complications in a broad range of mammalian hosts. One common feature of trypanosomosis is the occurrence of anemia, caused by an imbalance between erythropoiesis and red blood cell clearance of aging erythrocytes. In murine models for T. brucei trypanosomosis, anemia is marked by a very sudden non-hemolytic loss of RBCs during the first-peak parasitemia control, followed by a short recovery phase and the subsequent gradual occurrence of an ever-increasing level of anemia. Using a newly developed quantitative pHrodo based in vitro erythrophagocytosis assay, combined with FACS-based ex vivo and in vivo results, we show that activated liver monocytic cells and neutrophils as well as activated splenic macrophages are the main cells involved in the occurrence of the early-stage acute anemia. In addition, we show that trypanosomosis itself leads to a rapid alteration of RBC membrane stability, priming the cells for accelerated phagocytosis.

Parasite biomass-related inflammation, endothelial activation, microvascular dysfunction and disease severity in vivax malaria.

Plasmodium vivax can cause severe malaria, however its pathogenesis is poorly understood. In contrast to P. falciparum, circulating vivax parasitemia is low, with minimal apparent sequestration in endothelium-lined microvasculature, and pathogenesis thought unrelated to parasite biomass. However, the relationships between vivax disease-severity and total parasite biomass, endothelial autocrine activation and microvascular dysfunction are unknown. We measured circulating parasitemia and markers of total parasite biomass (plasma parasite lactate dehydrogenase [pLDH] and PvLDH) in adults with severe (n = 9) and non-severe (n = 53) vivax malaria, and examined relationships with disease-severity, endothelial activation, and microvascular function. Healthy controls and adults with non-severe and severe falciparum malaria were enrolled for comparison. Median peripheral parasitemia, PvLDH and pLDH were 2.4-fold, 3.7-fold and 6.9-fold higher in severe compared to non-severe vivax malaria (p = 0.02, p = 0.02 and p = 0.015, respectively), suggesting that, as in falciparum malaria, peripheral P. vivax parasitemia underestimates total parasite biomass, particularly in severe disease. P. vivax schizonts were under-represented in peripheral blood. Severe vivax malaria was associated with increased angiopoietin-2 and impaired microvascular reactivity. Peripheral vivax parasitemia correlated with endothelial activation (angiopoietin-2, von-Willebrand-Factor [VWF], E-selectin), whereas markers of total vivax biomass correlated only with systemic inflammation (IL-6, IL-10). Activity of the VWF-cleaving-protease, ADAMTS13, was deficient in proportion to endothelial activation, IL-6, thrombocytopenia and vivax disease-severity, and associated with impaired microvascular reactivity in severe disease. Impaired microvascular reactivity correlated with lactate in severe vivax malaria. Findings suggest that tissue accumulation of P. vivax may occur, with the hidden biomass greatest in severe disease and capable of mediating systemic inflammatory pathology. The lack of association between total parasite biomass and endothelial activation is consistent with accumulation in parts of the circulation devoid of endothelium. Endothelial activation, associated with circulating parasites, and systemic inflammation may contribute to pathology in vivax malaria, with microvascular dysfunction likely contributing to impaired tissue perfusion.