Cardiac involvement in Chagas disease and African trypanosomiasis

Trypanosomiases are diseases caused by various species of protozoan parasite in the genus Trypanosoma, each presenting with distinct clinical manifestations and prognoses. Infections can affect multiple organs, with Trypanosoma cruzi predominantly affecting the heart and digestive system, leading to American trypanosomiasis or Chagas disease, and Trypanosoma brucei primarily causing a disease of the central nervous system known as human African trypanosomiasis or sleeping sickness. In this Review, we discuss the effects of these infections on the heart, with particular emphasis on Chagas disease, which continues to be a leading cause of cardiomyopathy in Latin America. The epidemiology of Chagas disease has changed substantially since 1990 owing to the emigration of over 30 million Latin American citizens, primarily to Europe and the USA. This movement of people has led to the global dissemination of individuals infected with T. cruzi. Therefore, cardiologists worldwide must familiarize themselves with Chagas disease and the severe, chronic manifestation - Chagas cardiomyopathy - because of the expanded prevalence of this disease beyond traditional endemic regions.

A murine model of Trypanosoma brucei-induced myocarditis and cardiac dysfunction

Trypanosoma brucei is a protozoan parasite that causes human and animal African trypanosomiases (HAT and AAT). Cardiac symptoms are commonly reported in HAT patients, and intracardiac parasites with accompanying myocarditis have been observed in both natural hosts and animal models of T. brucei infection. Despite the importance of T. brucei as a cause of cardiac dysfunction and the dramatic socioeconomic impact of African trypanosomiases in sub-Saharan Africa, there are currently no reproducible murine models of T. brucei-associated cardiomyopathy. We present the first clinically relevant, reproducible murine model of cardiac dysfunction in chronic T. brucei infection. Similar to humans, mice showed histological evidence of myocarditis and elevation of serum NT-proBNP with electrocardiographic abnormalities. Serum NT-proBNP levels were elevated prior to the development of severe ventricular dysfunction. On flow cytometry, myocarditis was associated with an increase of most myocardial immune cell populations, including multiple T cell and macrophage subsets, corroborating the notion that T. brucei-associated cardiac damage is an immune-mediated event. This novel mouse model represents a powerful and practical tool to investigate the pathogenesis of T. brucei-mediated heart damage and supports the development of therapeutic options for T. brucei-associated cardiac disease.

Original algorithms for the detection of cardiovascular involvement of neglected tropical diseases

INTRODUCTION

Neglected tropical diseases (NTDs) introduce considerable morbidity and mortality on a global scale, directly impacting over 1 billion individuals as well as their families and communities. Afflicted individuals may have limited access to resources and care in these regions, contributing to a high proportion of chronic, progressive, and systemic disease. The cardiovascular system is at particular risk of demise for several NTDs, yet remains largely unstudied due in part to the lack of robust data collection mechanisms in the most impacted regions.

AREAS COVERED

The present review is a part of the Neglected Tropical Diseases and other Infectious Diseases affecting the Heart (NET-Heart) Project, aiming at summarizing the current knowledge on cardiovascular implications of NTDs and providing diagnostic as well as management recommendations which can be tailored to low-resource settings. The diagnostic and management algorithms of 13 unique NTDs are presented and summarized.

EXPERT OPINION

Recognizing cardiac manifestations of NTDs can significantly alter disease trajectory and all physicians benefit from improved knowledge about NTDs. Great potential exists to advance patient care by improving data collection, communication, and international collaboration.

Myocarditis: Etiology, Pathogenesis, and Their Implications in Clinical Practice

Myocarditis is an inflammatory disease of the myocardium caused by infectious or non-infectious agents. It can lead to serious short-term and long-term sequalae, such as sudden cardiac death or dilated cardiomyopathy. Due to its heterogenous clinical presentation and disease course, challenging diagnosis and limited evidence for prognostic stratification, myocarditis poses a great challenge to clinicians. As it stands, the pathogenesis and etiology of myocarditis is only partially understood. Moreover, the impact of certain clinical features on risk assessment, patient outcomes and treatment options is not entirely clear. Such data, however, are essential in order to personalize patient care and implement novel therapeutic strategies. In this review, we discuss the possible etiologies of myocarditis, outline the key processes governing its pathogenesis and summarize best available evidence regarding patient outcomes and state-of-the-art therapeutic approaches.

Infections and Cardiovascular Disease: JACC Focus Seminar 1/4

The burden of cardiovascular diseases is sharply rising in low- and middle-income countries (LMICs). Along with the increasing rates of cardiovascular risk factors in these regions, there is a growing recognition of the contribution of neglected tropical diseases and other infections. Several cardiac implications of these infections have been reported but have not yet been validated by robust population data. This is in part due to limited access to health care and insufficient data collection infrastructure in many LMICs. Therefore, the true impact of these infections on the cardiovascular system may be underestimated, because of both underdiagnosis and underreporting bias. There is an urgent need to thoroughly delineate the cardiac impact of these conditions with elevated prevalence in LMICs and to propose strategies to reduce the negative consequences of these diseases in health systems with limited resources.

Prevalence and outcomes of malaria as co-infection among patients with human African trypanosomiasis: a systematic review and meta-analysis

Human African trypanosomiasis (HAT) is endemic in Africa; hence, the possibility of co-infection with malaria among patients with HAT exists. The present study investigated co-infection with malaria among patients with HAT to provide current evidence and characteristics to support further studies. Potentially relevant studies that reported Plasmodium spp. infection in patients with HAT was searched in PubMed, Web of Science, and Scopus. The risk of bias among the included studies was assessed using the checklist for analytical cross-sectional studies developed by the Joanna Briggs Institute. The pooled prevalence of Plasmodium spp. infection in patients with HAT was quantitatively synthesized using a random-effects model. Subgroup analyses of study sites and stages of HAT were performed to identify heterogeneity regarding prevalence among the included studies. The heterogeneity of the outcome among the included studies was assessed using Cochran’s Q and I² statistics for consistency. Publication bias was assessed if the number of included studies was 10 or more. For qualitative synthesis, a narrative synthesis of the impact of Plasmodium spp. infection on the clinical and outcome characteristics of HAT was performed when the included studies provided qualitative data. Among 327 studies identified from three databases, nine studies were included in the systematic review and meta-analysis. The prevalence of Plasmodium spp. co-infection (692 cases) among patients with HAT (1523 cases) was 50% (95% confidence interval [CI] = 28–72%, I² = 98.1%, seven studies). Subgroup analysis by type of HAT (gambiense or rhodesiense HAT) revealed that among patients with gambiense HAT, the pooled prevalence of Plasmodium spp. infection was 46% (95% CI = 14–78%, I² = 96.62%, four studies), whereas that among patients with rhodesiense HAT was 44% (95% CI = 40–49%, I² = 98.3%, three studies). Qualitative syntheses demonstrated that Plasmodium spp. infection in individuals with HAT might influence the risk of encephalopathy syndrome, drug toxicity, and significantly longer corrected QT time. Moreover, longer hospital stays and higher treatment costs were recorded among co-infected individuals. Because of the high prevalence of malaria among patients with HAT, some patients were positive for malaria parasites despite being asymptomatic. Therefore, it is suggested to test every patient with HAT for malaria before HAT treatment. If malaria is present, then antimalarial treatment is recommended before HAT treatment. Antimalarial treatment in patients with HAT might decrease the probability of poor clinical outcomes and case fatality in HAT.

Thinking outside the blood: Perspectives on tissue-resident Trypanosoma brucei

Trypanosoma brucei is a protozoan parasite that causes human and animal African trypanosomiases (HAT and AAT). In the mammalian host, the parasite lives entirely extracellularly, in both the blood and interstitial spaces in tissues. Although most T. brucei research has focused on the biology of blood- and central nervous system (CNS)-resident parasites, a number of recent studies have highlighted parasite reservoirs in the dermis and adipose tissue, leading to a renewed interest in tissue-resident parasite populations. In light of this renewed interest, work describing tissue-resident parasites can serve as a valuable resource to inform future investigations of tissue-resident T. brucei. Here, we review this body of literature, which describes infections in humans, natural hosts, and experimental animal models, providing a wealth of information on the distribution and biology of extravascular parasites, the corresponding immune response in each tissue, and resulting host pathology. We discuss the implications of these studies and future questions in the study of extravascular T. brucei.

Long-term sequelae of congenital gambiense human African trypanosomiasis

BACKGROUND

The clinical presentation of gambiense human African trypanosomias (gHAT) is generally considered to be the same among children and adults. In general, when describing the clinical presentation of children with gHAT, no differentiation is made between congenital gHAT and gHAT acquired later. There is a lack of knowledge regarding the signs and symptoms attributable to congenital gHAT and its long-term sequelae.

METHODS

Following an evaluation of the hospital register for gHAT, the authors observed that six children born to mothers with gHAT during their pregnancies still had sequelae of the infection. The six mothers were interviewed about their respective pregnancies and the developmental history of the children borne to the infected mothers. Furthermore, the children then underwent a complete physical examination with a focus on neuropsychiatric signs and symptoms.

RESULTS

Five of the six patients are still seriously disabled. Behavioral changes are present in four patients, tremor, speech impairment, involuntary movements and pathologic the Barrés test and Mingazzini test in three patients and convulsions, pyramidal signs and decreased muscle tonus in two patients. Two patients cannot work and one has a sphincter disorder.

CONCLUSIONS

Our study suggests that congenital gHAT may lead to long-lasting sequelae in babies born to mothers treated after delivery. The risk of embryo toxicity of treatment of mothers with gHAT must be balanced against the risk of congenital gHAT with long-term sequelae.

Human African trypanosomiasis & heart

INTRODUCTION

Human African Trypanosomiasis is a neglected tropical disease resulting from the infection with the parasite Trypanosoma brucei. Neurological compromise often dominates, and the impact of cardiovascular involvement has not been fully investigated. Recently, publications indicate that cardiovascular compromise is more frequent than previously thought. Early detection of cardiac complications may be of utmost importance for healthcare teams.

AREA COVERED

As a part of the 'Neglected Tropical Diseases and other Infectious Diseases involving the Heart' (the NET-Heart Project), the purpose of this article is to review all the information available regarding cardiovascular implications of this disease, focusing on diagnosis and treatment, and proposing strategies for early detection of cardiac manifestations. An electronic systematic literature review of articles published in MEDLINE, PubMed and EMBASE was performed. From 50 initial studies, 18 were selected according to inclusion criteria. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement was used for conducting and reporting this review.

EXPERT OPINION

Cardiovascular compromise through infiltrative and inflammatory mechanisms seems to be frequent, and includes a wide spectrum of severity. Conventional 12-lead electrocardiogram could be a useful test for screening cardiovascular manifestations and used as a guide for considering specific treatments or more sophisticated diagnostic tools.

Sleeping hearts: 12 years after a follow up study on cardiac findings due to sleeping sickness

Both American Trypanosomiasis (Chagas disease) and Human African Trypanosomiasis (HAT) are diseases caused by single-celled flagellate protozoan parasites. While cardiac complications such as conduction problems and heart failure are very common in Chagas disease there is little known about the long-term effects of Human African Trypanosomiasis (HAT) on cardiac sequelae in Sub-Saharan Africa, where heart failure has become an increasing problem and growing burden.

In the context of clinical trials conducted between 2004 and 2005 in the Democratic Republic of the Congo (DRC), the prevalence of HAT related signs and symptoms and an ECG were evaluated prior to the initiation of treatment.

The object of this follow-up study in 2017 was to assess the prevalence of cardiac sequelae in the same 51 first stage and 18  second stage HAT patients 12–13 years after their treatment by conducting a clinical examination and an ECG. A control group matched by age (± 5 years), sex and whenever possible form the same village was enrolled.

There were no significant differences in the prevalence of cardiac symptoms and in ECG findings between patients and their controls at the time of the follow-up evaluation. Repolarization changes disappeared or improved in 24.7% of HAT patients and were even less frequent than in the control group. Peripheral low voltage was the only parameter that increased over time in HAT patients and in three patients, new conduction problems in the ECG (ventricular bigeminy, RBBB, and bifascicular block) could be found, although none of these findings was clinically significant. However, the appearance of these conduction problems might represent an early indication of a HAT related cardiomyopathy or ongoing subclinical infection. This hypothesis would be supported by the findings of an older study in which antibodies (IFAT) against trypanosomiasis in 27% of Cameroonian patients with dilated cardiomyopathy compared to 2% in normal controls had been observed.

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In American Trypanosomiasis (Chagas)cardiac complications are common, but no significant cardiac sequelae was found in African Trypanosomiasis.

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12 years after treatment none of the patients developed cardiac failure and there was no sudden death due to arrhythmia.

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The appearance of cardiac conduction problems in the actual ECG could be an early indication of a HAT related cardiomyopathy.

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Overall, as compared to Chagas disease, HAT seems to have minimal influence on the heart even over a long follow-up time.

Tissue tropism in parasitic diseases

Parasitic diseases, such as sleeping sickness, Chagas disease and malaria, remain a major cause of morbidity and mortality worldwide, but particularly in tropical, developing countries. Controlling these diseases requires a better understanding of host-parasite interactions, including a deep appreciation of parasite distribution in the host. The preferred accumulation of parasites in some tissues of the host has been known for many years, but recent technical advances have allowed a more systematic analysis and quantifications of such tissue tropisms. The functional consequences of tissue tropism remain poorly studied, although it has been associated with important aspects of disease, including transmission enhancement, treatment failure, relapse and clinical outcome. Here, we discuss current knowledge of tissue tropism in Trypanosoma infections in mammals, describe potential mechanisms of tissue entry, comparatively discuss relevant findings from other parasitology fields where tissue tropism has been extensively investigated, and reflect on new questions raised by recent discoveries and their potential impact on clinical treatment and disease control strategies.

Gambiense Human African Trypanosomiasis Sequelae after Treatment: A Follow-Up Study 12 Years after Treatment

The clinical presentation of Human African Trypanosomiasis (HAT) due to Trypanosoma brucei gambiense is well known, but knowledge on long-term sequelae is limited. In the frame of studies conducted between 2004 and 2005 in the Democratic Republic of the Congo (DRC), the prevalence of HAT related signs and symptoms were evaluated before the start of treatment and at the end of treatment. To explore possible long-term sequelae, the same clinical parameters were assessed in 2017 in 51 first stage and 18 second stage HAT patients. Signs and symptoms 12–13 years after treatment were compared to before and immediately after treatment and to controls matched for sex and age (±5 years). In first stage HAT patients, the prevalence of all signs and symptoms decreased compared to before treatment but were still higher after 12–13 years than immediately at the end of treatment and in the control group. In second stage HAT patients, all HAT-specific findings had continuously decreased to the point where they were in the range of the healthy control group. In a selection of oligosymptomatic first stage HAT patients, no trypanosomes were detected in the blood by microscopic examination or PCR. An oligosymptomatic presentation of HAT due to the persistence of parasites in compartments, where first stage HAT medications do not penetrate, could not be ruled out.

Toxocariasis-associated cardiac diseases--A systematic review of the literature

Toxocariasis, caused by Toxocara canis or Toxocara catis, is a worldwide occurring parasitic disease, reaching high prevalences especially in tropical and subtropical countries. The clinical presentation can range from asymptomatic seropositivity to life threatenting disease, depending on the organ system involved. Cardiac involvement, one of the possible manifestations of human Toxocara spp. infection, is rarely reported in case reports. As far as we know, no systematic reviews of clinical presentations have been published till now and no clear recommendations regarding the treatment of Toxocara spp. infection involving the heart exist. In a systematic review of the literature, 24 published cases of Toxocara spp. infection involving the heart were identified. The cardiac entities described included myocarditis, pericarditis, and Loeffler's endocarditis. The clinical presentation ranged from asymptomatic or mild disease to life threatening myocarditis/pericarditis with heart failure or cardiac tamponade, leading to death. In most cases, the diagnosis was based on a combination of clinical, laboratory and radiological findings. Only in three of the nine cases in which histological analysis was performed (either pre- or post-mortem), granulomas or remnants of the parasite were detected. In the other six cases, findings were non-specific; the damage of the heart was equally caused by direct invasion of the larvae and by immunological reactions, either caused by the systemic hypereosinophilia or by the presence of the larvae in the tissue. The treatment regimen described mostly consisted of anthelmintic drugs in combination with corticosteroids. Even though dosage and duration of treatment varied widely, ranging from days to months, most patients were treated successfully. Cardiac involvement in Toxocara spp. infection is a rare but potentially life-threatening complication of a very common disease. The therapeutic regimens vary widely especially with regard to the duration of therapy, however, the combination of an anthelmintic drug and a corticosteroid appears to be a valuable option. For the daily clinical work, tissue manifestation by parasites should be considered in cases of unspecific organ manifestations, (i.e. heart, lungs, liver), accompanied by fever and eosinophilia with or without allergic skin rashes.

A Pre-clinical Animal Model of Trypanosoma brucei Infection Demonstrating Cardiac Dysfunction

African trypanosomiasis (AT), caused by Trypanosoma brucei species, results in both neurological and cardiac dysfunction and can be fatal if untreated. Research on the pathogenesis and treatment of the disease has centred to date on the characteristic neurological symptoms, whereas cardiac dysfunction (e.g. ventricular arrhythmias) in AT remains largely unstudied. Animal models of AT demonstrating cardiac dysfunction similar to that described in field cases of AT are critically required to transform our understanding of AT-induced cardiac pathophysiology and identify future treatment strategies. We have previously shown that T. brucei can interact with heart muscle cells (cardiomyocytes) to induce ventricular arrhythmias in ex vivo adult rat hearts. However, it is unknown whether the arrhythmias observed ex vivo are also present during in vivo infection in experimental animal models. Here we show for the first time the characterisation of ventricular arrhythmias in vivo in two animal models of AT infection using electrocardiographic (ECG) monitoring. The first model utilised a commonly used monomorphic laboratory strain, Trypanosoma brucei brucei Lister 427, whilst the second model used a pleomorphic laboratory strain, T. b. brucei TREU 927, which demonstrates a similar chronic infection profile to clinical cases. The frequency of ventricular arrhythmias and heart rate (HR) was significantly increased at the endpoint of infection in the TREU 927 infection model, but not in the Lister 427 infection model. At the end of infection, hearts from both models were isolated and Langendorff perfused ex vivo with increasing concentrations of the β-adrenergic agonist isoproterenol (ISO). Interestingly, the increased frequency of arrhythmias observed in vivo in the TREU 927 infection model was lost upon isolation of the heart ex vivo, but re-emerged with the addition of ISO. Our results demonstrate that TREU 927 infection modifies the substrate of the myocardium in such a way as to increase the propensity for ventricular arrhythmias in response to a circulating factor in vivo or β-adrenergic stimulation ex vivo. The TREU 927 infection model provides a new opportunity to accelerate our understanding of AT-related cardiac pathophysiology and importantly has the required sensitivity to monitor adverse cardiac-related electrical dysfunction when testing new therapeutic treatments for AT.

Clinical profiles, disease outcome and co-morbidities among T. b. rhodesiense sleeping sickness patients in Uganda

BACKGROUND

The acute form of Human African Trypanosomiasis (HAT, also known as Sleeping sickness) caused by Trypanosoma brucei rhodesiense has been shown to have a wide spectrum of focus specific clinical presentation and severity in East and Southern Africa. Indeed HAT occurs in regions endemic for other tropical diseases, however data on how these co-morbidities might complicate the clinical picture and affect disease outcome remains largely scanty. We here describe the clinical presentation, presence of co-infections, and how the latter impact on HAT prognosis.

METHODS AND FINDINGS

We carried out a retrospective analysis of clinical data from 258 sleeping sickness patients reporting to Lwala hospital between 2005 and 2012. The mean patient age was 28.6 years with a significant number of cases below 18 years (p< 0.0001). About 93.4% of the cases were diagnosed as late stage (p< 0.0001). The case fatality rate was 10.5% with post treatment reactive encephalopathys reported in 7.9% of the cases, of whom 36.8% eventually died. Fever was significantly (p = 0.045) higher in patients under 18 years. Of the early stage patients, 26.7% and 6.7% presented with late stage signs of sleep disorder and mental confusion respectively. Among the co-infections, malaria was significantly more prevalent (28.9%; p< 0.0001) followed by urinary tract infections (4.2%). Co-infections were present in 14.3% of in-hospital deaths, 38.5% of which were recorded as Malaria. Malaria was significantly more common in patients under 18 years (45.5%; p< 0.02), and was reported in 60% of the fatal cases in this age group.

CONCLUSIONS

We show a wide spectrum of sleeping sickness clinical presentation and disease outcome that was apparently not significantly influenced by concurrent infections. It would thus be interesting to determine the host and/or parasite factors that might be responsible for the observed diverse clinical presentation.

Trypanosoma brucei cathepsin-L increases arrhythmogenic sarcoplasmic reticulum-mediated calcium release in rat cardiomyocytes

Aims

African trypanosomiasis, caused by Trypanosoma brucei species, leads to both neurological and cardiac dysfunction and can be fatal if untreated. While the neurological-related pathogenesis is well studied, the cardiac pathogenesis remains unknown. The current study exposed isolated ventricular cardiomyocytes and adult rat hearts to T. brucei to test whether trypanosomes can alter cardiac function independent of a systemic inflammatory/immune response.

Methods and results

Using confocal imaging, T. brucei and T. brucei culture media (supernatant) caused an increased frequency of arrhythmogenic spontaneous diastolic sarcoplasmic reticulum (SR)-mediated Ca²⁺ release (Ca²⁺ waves) in isolated adult rat ventricular cardiomyocytes. Studies utilising inhibitors, recombinant protein and RNAi all demonstrated that this altered SR function was due to T. brucei cathepsin-L (TbCatL). Separate experiments revealed that TbCatL induced a 10–15% increase of SERCA activity but reduced SR Ca²⁺ content, suggesting a concomitant increased SR-mediated Ca²⁺ leak. This conclusion was supported by data demonstrating that TbCatL increased Ca²⁺ wave frequency. These effects were abolished by autocamtide-2-related inhibitory peptide, highlighting a role for CaMKII in the TbCatL action on SR function. Isolated Langendorff perfused whole heart experiments confirmed that supernatant caused an increased number of arrhythmic events.

Conclusion

These data demonstrate for the first time that African trypanosomes alter cardiac function independent of a systemic immune response, via a mechanism involving extracellular cathepsin-L-mediated changes in SR function.

Human African trypanosomiasis

Human African trypanosomiasis (sleeping sickness) is caused by the unicellular parasite Trypanosoma brucei and transmitted by tsetse flies. It occurs exclusively in sub-Saharan Africa, usually in rural areas affected by civil conflicts and neglected health systems. Reported cases are fewer than 10,000/year, which classifies it as one of the most neglected tropical diseases. Because sleeping sickness is fatal if not treated, it has to be included in the differential diagnosis of every febrile traveler returning from a game park in East Africa. Elimination of the disease is considered feasible provided better tools for diagnosis and treatment can be made available.

Sleeping sickness in travelers - do they really sleep?

The number of imported Human African Trypanosomiasis (HAT) cases in non-endemic countries has increased over the last years. The objective of this analysis is to describe the clinical presentation of HAT in Caucasian travelers. Literature was screened (MEDLINE, Pubmed) using the terms "Human African Trypanosomiasis", "travelers" and "expatriates"; all European languages except Slavic ones were included. Publications without clinical description of patients were only included in the epidemiological analysis. Forty-five reports on Caucasians with T.b. rhodesiense and 15 with T.b. gambiense infections were included in the analysis of the clinical parameters. Both species have presented with fever (T.b. rhodesiense 97.8% and T.b. gambiense 93.3%), headache (50% each) and a trypanosomal chancre (T.b. rhodesiense 84.4%, T.b. gambiense 46.7%). While sleeping disorders dominate the clinical presentation of HAT in endemic regions, there have been only rare reports in travelers: insomnia (T.b. rhodesiense 7.1%, T.b. gambiense 21.4%), diurnal somnolence (T.b. rhodesiense 4.8%, T.b. gambiense none). Surprisingly, jaundice has been seen in 24.2% of the Caucasian T.b. rhodesiense patients, but has never been described in HAT patients in endemic regions. These results contrast to the clinical presentation of T.b. gambiense and T.b. rhodesiense HAT in Africans in endemic regions, where the presentation of chronic T.b. gambiense and acute T.b. rhodesiense HAT is different. The analysis of 14 reports on T.b. gambiense HAT in Africans living in a non-endemic country shows that neurological symptoms such as somnolence (46.2%), motor deficit (64.3%) and reflex anomalies (14.3%) as well as psychiatric symptoms such as hallucinations (21.4%) or depression (21.4%) may dominate the clinical picture. Often, the diagnosis has been missed initially: some patients have even been hospitalized in psychiatric clinics. In travelers T.b. rhodesiense and gambiense present as acute illnesses and chancres are frequently seen. The diagnosis of HAT in Africans living outside the endemic region is often missed or delayed, leading to presentation with advanced stages of the disease.

Sleeping sickness

Human African trypanosomiasis (HAT), or sleeping sickness, is a vector-borne disease that flourishes in impoverished, rural parts of sub-Saharan Africa. It is caused by infection with the protozoan parasite Trypanosoma brucei and is transmitted by tsetse flies of the genus Glossina. The majority of cases are caused by T. b. gambiense, which gives rise to the chronic, anthroponotic endemic disease in Western and Central Africa. Infection with T. b. rhodesiense leads to the acute, zoonotic form of Eastern and Southern Africa. The parasites live and multiply extracellularly in the blood and tissue fluids of their human host. They have elaborated a variety of strategies for invading hosts, to escape the immune system and to take advantage of host growth factors. HAT is a challenging and deadly disease owing to its complex epidemiology and clinical presentation and, if left untreated, can result in high death rates. As one of the most neglected tropical diseases, HAT is characterized by the limited availability of safe and cost-effective control tools. No vaccine against HAT is available, and the toxicity of existing old and cumbersome drugs precludes the adoption of control strategies based on preventive chemotherapy. As a result, the keystones of interventions against sleeping sickness are active and passive case-finding for early detection of cases followed by treatment, vector control and animal reservoir management. New methods to diagnose and treat patients and to control transmission by the tsetse fly are needed to achieve the goal of global elimination of the disease.

Human African trypanosomiasis in endemic populations and travellers

Human African trypanosomiasis (HAT) or sleeping sickness is caused by the protozoan parasites Trypanosoma brucei (T.b.) gambiense (West African form) and T.b. rhodesiense (East African form) that are transmitted by the bite of the tsetse fly, Glossina spp.. Whereas most patients in endemic populations are infected with T.b. gambiense, most tourists are infected with T.b. rhodesiense. In endemic populations, T.b. gambiense HAT is characterized by chronic and intermittent fever, headache, pruritus, and lymphadenopathy in the first stage and by sleep disturbances and neuro-psychiatric disorders in the second stage. Recent descriptions of the clinical presentation of T.b. rhodesiense in endemic populations show a high variability in different foci. The symptomatology of travellers is markedly different from the usual textbook descriptions of African HAT patients. The onset of both infections is almost invariably an acute and febrile disease. Diagnosis and treatment are difficult and rely mostly on old methods and drugs. However, new molecular diagnostic technologies are under development. A promising new drug combination is currently evaluated in a phase 3 b study and further new drugs are under evaluation.

Clinical presentation of T.b. rhodesiense sleeping sickness in second stage patients from Tanzania and Uganda

Background

A wide spectrum of disease severity has been described for Human African Trypanosomiasis (HAT) due to Trypanosoma brucei rhodesiense (T.b. rhodesiense), ranging from chronic disease patterns in southern countries of East Africa to an increase in virulence towards the north. However, only limited data on the clinical presentation of T.b. rhodesiense HAT is available. From 2006-2009 we conducted the first clinical trial program (Impamel III) in T.b. rhodesiense endemic areas of Tanzania and Uganda in accordance with international standards (ICH-GCP). The primary and secondary outcome measures were safety and efficacy of an abridged melarsoprol schedule for treatment of second stage disease. Based on diagnostic findings and clinical examinations at baseline we describe the clinical presentation of T.b. rhodesiense HAT in second stage patients from two distinct geographical settings in East Africa.

Methodology/Principal Findings:

138 second stage patients from Tanzania and Uganda were enrolled. Blood samples were collected for diagnosis and molecular identification of the infective trypanosomes, and T.b. rhodesiense infection was confirmed in all trial subjects. Significant differences in diagnostic parameters and clinical signs and symptoms were observed: the median white blood cell (WBC) count in the cerebrospinal fluid (CSF) was significantly higher in Tanzania (134cells/mm³) than in Uganda (20cells/mm³; p<0.0001). Unspecific signs of infection were more commonly seen in Uganda, whereas neurological signs and symptoms specific for HAT dominated the clinical presentation of the disease in Tanzania. Co-infections with malaria and HIV did not influence the clinical presentation nor treatment outcomes in the Tanzanian study population.

Conclusions/Significance

We describe a different clinical presentation of second stage T.b. rhodesiense HAT in two distinct geographical settings in East Africa. In the ongoing absence of sensitive diagnostic tools and safe drugs to diagnose and treat second stage T.b. rhodesiense HAT an early identification of the disease is essential. A detailed understanding of the clinical presentation of T.b. rhodesiense HAT among health personnel and affected communities is vital, and awareness of regional characteristics, as well as implications of co-infections, can support decision making and differential diagnosis.

Sleeping sickness, or Human African Trypanosomiasis (HAT), caused by Trypanosoma brucei rhodesiense is one of the most neglected tropical diseases. It affects mainly rural, poor East African populations and has very high socio-economic impacts. T.b. rhodesiense HAT is an acute disease; patients quickly progress from the first stage, where trypanosomes are detectable in blood and lymph, to the second stage, where parasites penetrate the central nervous system. If left untreated, T.b. rhodesiense HAT is fatal. Disease control is hampered by the absence of sensitive diagnostic tools and safe drugs. Second stage patients can only be treated with melarsoprol, a highly toxic, arsenical drug. It is more difficult to treat patients successfully at advanced stages of the disease, and late onset of treatment should be avoided. Yet, most patients are treated for other conditions prior to HAT diagnosis. Therefore, it is important that health personnel in T.b. rhodesiense endemic regions have a detailed understanding of the clinical presentation of the disease and consider regional characteristics of T.b. rhodesiense HAT for decision making and differential diagnosis.

Chemotherapy against human African trypanosomiasis: Is there a road to success?

For over fifty years, human African trypanosomiasis (HAT, sleeping sickness) has been treated with suramin, pentamidine and the very toxic organo-arsenical melarsoprol that was the only drug available for effective treatment of the second stage of the disease. Recently there have been significant efforts using molecular and biochemical approaches to drug design, including high-throughput screening, but the number of lead compounds with promising activity againstT. bruceispp. and an acceptable toxicity index has remained astonishingly small. Clinical research continues to be difficult due to the economic constraints and the complexity of trials on a low prevalence disease in remote and impoverished African regions. Despite those limitations the situation for the patients is improving thanks to the combination of a number of critical factors. By the late 1990s the disease had reached epidemic levels that triggered political support. WHO would sign a donation agreement with the manufacturers for all drugs to treat HAT. A result of this agreement was that eflornithine which is much safer than melarsoprol became available and widely used by non-governmental organizations. TheImpamelI and II programmes demonstrated that against all odds the conduct of clinical trials on HAT was feasible. This allowed the initiation of trials on combination therapies which eventually resulted in the nifurtimox-eflornithine combination treatment (NECT). This combination is currently being introduced as first line treatment, and there is even the prospect of having a new compound, fexinidazole, in the development pipeline. This review summarizes the key information about the existing drugs and gives a comprehensive summary about the recent and currently ongoing efforts towards new drugs.

Trypanosomiasis, cardiomyopathy and the risk of ischemic stroke

American (Chagas disease) and African (sleeping sickness) trypanosomiasis are neglected tropical diseases and are a heavy burden in Latin America and Africa, respectively. Chagas disease is an independent risk factor for stroke. Apical aneurysm, heart failure and cardiac arrhythmias are associated with ischemic stroke in chagasic cardiomyopathy. Not all chagasic patients who suffer an ischemic stroke have a severe cardiomyopathy, and stroke may be the first manifestation of Chagas disease. Cardioembolism affecting the middle cerebral artery is the most common stroke subtype. Risk of recurrence is high and careful evaluation of recurrence risk should be addressed. Repolarization changes, low voltage and prolonged QT interval are common electrocardiography alterations in human African trypanosomiasis, and can be found in more than 70% of patients. Epidemiological studies are needed to asses the risk of stroke in African trypanosomiasis perimyocarditis.

Cardiac involvement with parasitic infections

Parasitic infections previously seen only in developing tropical settings can be currently diagnosed worldwide due to travel and population migration. Some parasites may directly or indirectly affect various anatomical structures of the heart, with infections manifested as myocarditis, pericarditis, pancarditis, or pulmonary hypertension. Thus, it has become quite relevant for clinicians in developed settings to consider parasitic infections in the differential diagnosis of myocardial and pericardial disease anywhere around the globe. Chagas' disease is by far the most important parasitic infection of the heart and one that it is currently considered a global parasitic infection due to the growing migration of populations from areas where these infections are highly endemic to settings where they are not endemic. Current advances in the treatment of African trypanosomiasis offer hope to prevent not only the neurological complications but also the frequently identified cardiac manifestations of this life-threatening parasitic infection. The lack of effective vaccines, optimal chemoprophylaxis, or evidence-based pharmacological therapies to control many of the parasitic diseases of the heart, in particular Chagas' disease, makes this disease one of the most important public health challenges of our time.

Human African trypanosomiasis

Human African trypanosomiasis (sleeping sickness) occurs in sub-Saharan Africa. It is caused by the protozoan parasite Trypanosoma brucei, transmitted by tsetse flies. Almost all cases are due to Trypanosoma brucei gambiense, which is indigenous to west and central Africa. Prevalence is strongly dependent on control measures, which are often neglected during periods of political instability, thus leading to resurgence. With fewer than 12 000 cases of this disabling and fatal disease reported per year, trypanosomiasis belongs to the most neglected tropical diseases. The clinical presentation is complex, and diagnosis and treatment difficult. The available drugs are old, complicated to administer, and can cause severe adverse reactions. New diagnostic methods and safe and effective drugs are urgently needed. Vector control, to reduce the number of flies in existing foci, needs to be organised on a pan-African basis. WHO has stated that if national control programmes, international organisations, research institutes, and philanthropic partners engage in concerted action, elimination of this disease might even be possible.

Novel S-adenosylmethionine decarboxylase inhibitors for the treatment of human African trypanosomiasis

Trypanosomiasis remains a significant disease across the sub-Saharan African continent, with 50,000 to 70,000 individuals infected. The utility of current therapies is limited by issues of toxicity and the need to administer compounds intravenously. We have begun a program to pursue lead optimization around MDL 73811, an irreversible inhibitor of S-adenosylmethionine decarboxylase (AdoMetDC). This compound is potent but in previous studies cleared rapidly from the blood of rats (T. L. Byers, T. L. Bush, P. P. McCann, and A. J. Bitonti, Biochem. J. 274:527-533). One of the analogs synthesized (Genz-644131) was shown to be highly active against Trypanosoma brucei rhodesiense in vitro (50% inhibitory concentration, 400 pg/ml). Enzyme kinetic studies showed Genz-644131 to be approximately fivefold more potent than MDL 73811 against the T. brucei brucei AdoMetDC-prozyme complex. This compound was stable in vitro in rat and human liver microsomal and hepatocyte assays, was stable in rat whole-blood assays, did not significantly inhibit human cytochrome P450 enzymes, had no measurable efflux in CaCo-2 cells, and was only 41% bound by serum proteins. Pharmacokinetic studies of mice following intraperitoneal dosing showed that the half-life of Genz-644131 was threefold greater than that of MDL 73811 (7.4 h versus 2.5 h). Furthermore, brain penetration of Genz-644131 was 4.3-fold higher than that of MDL 73811. Finally, in vivo efficacy studies of T. b. brucei strain STIB 795-infected mice showed that Genz-644131 significantly extended survival (from 6.75 days for controls to >30 days for treated animals) and cured animals infected with T. b. brucei strain LAB 110 EATRO. Taken together, the data strengthen validation of AdoMetDC as an important parasite target, and these studies have shown that analogs of MDL 73811 can be synthesized with improved potency and brain penetration.

Cardiac alterations in human African trypanosomiasis (T.b. gambiense) with respect to the disease stage and antiparasitic treatment

Background

In Human African Trypanosomiasis, neurological symptoms dominate and cardiac involvement has been suggested. Because of increasing resistance to the available drugs for HAT, new compounds are desperately needed. Evaluation of cardiotoxicity is one parameter of drug safety, but without knowledge of the baseline heart involvement in HAT, cardiologic findings and drug-induced alterations will be difficult to interpret. The aims of the study were to assess the frequency and characteristics of electrocardiographic findings in the first stage of HAT, to compare these findings to those of second stage patients and healthy controls and to assess any potential effects of different therapeutic antiparasitic compounds with respect to ECG changes after treatment.

Methods

Four hundred and six patients with first stage HAT were recruited in the Democratic Republic of Congo, Angola and Sudan between 2002 and 2007 in a series of clinical trials comparing the efficacy and safety of the experimental treatment DB289 to the standard first stage treatment, pentamidine. These ECGs were compared to the ECGs of healthy volunteers (n = 61) and to those of second stage HAT patients (n = 56).

Results

In first and second stage HAT, a prolonged QTc interval, repolarization changes and low voltage were significantly more frequent than in healthy controls. Treatment in first stage was associated with repolarization changes in both the DB289 and the pentamidine group to a similar extent. The QTc interval did not change during treatment.

Conclusions

Cardiac involvement in HAT, as demonstrated by ECG alterations, appears early in the evolution of the disease. The prolongation of the QTC interval comprises a risk of fatal arrhythmias if new drugs with an additional potential of QTC prolongation will be used. During treatment ECG abnormalities such as repolarization changes consistent with peri-myocarditis occur frequently and appear to be associated with the disease stage, but not with a specific drug.

In Human African Trypanosomiasis (HAT), neurological symptoms dominate and cardiac involvement has been suggested. Because of increasing resistance to the available drugs for HAT, new compounds are desperately needed. Evaluation of cardiotoxicity is one parameter of drug safety, but without knowledge of the baseline heart involvement in HAT, cardiologic findings and drug-induced alterations will be difficult to interpret. The electrocardiogram (ECG) is a tool to evaluate cardiac involvement and the risk of arrythmias. We analysed the ECG of 465 HAT patients and compared them with the ECG of 61 healthy volunteers. In HAT patients the QTc interval was prolonged. This comprises a risk of fatal arrhythmias if new drugs with antiarrhythmic potential will be used. Further, repolarization changes and low voltage were more frequent than in healthy controls. This could be explained by an inflammation of the heart. Treatment of HAT was associated with appearance of repolarization changes but not with a QTc prolongation. These changes appear to be associated with the disease, but not with a specific drug. The main conclusion of this study is that heart involvement is frequent in HAT and mostly well tolerated. However, it can become relevant, if new compounds with antiarrhythmic potential will be used.

The burden of human African trypanosomiasis

Human African trypanosomiasis (HAT, or sleeping sickness) is a protozoan parasitic infection caused by Trypanosoma brucei rhodesiense or Trypanosoma brucei gambiense. These are neglected tropical diseases, and T.b. rhodesiense HAT is a zoonosis. We review current knowledge on the burden of HAT in sub-Saharan Africa, with an emphasis on the disability-adjusted life year (DALY), data sources, and methodological issues relating to the use of this metric for assessing the burden of this disease. We highlight areas where data are lacking to properly quantify the impact of these diseases, mainly relating to quantifying under-reporting and disability associated with infection, and challenge the HAT research community to tackle the neglect in data gathering to enable better evidence-based assessments of burden using DALYs or other appropriate measures.

Cardiac involvement in African and American trypanosomiasis

American trypanosomiasis (Chagas disease) and human African trypanosomiasis (HAT; sleeping sickness) are both caused by single-celled flagellates that are transmitted by arthropods. Cardiac problems are the main cause of morbidity in chronic Chagas disease, but neurological problems dominate in HAT. Physicians need to be aware of Chagas disease and HAT in patients living in or returning from endemic regions, even if they left those regions long ago. Chagas heart disease has to be taken into account in the differential diagnosis of cardiomyopathy, primarily in patients with pathological electrocardiographic (ECG) findings, such as right bundle branch block or left anterior hemiblock, with segmental wall motion abnormalities or aneurysms on echocardiography, and in young patients with stroke in the absence of arterial hypertension. In HAT patients, cardiac involvement as seen by ECG alterations, such as repolarisation changes and low voltage, is frequent. HAT cardiopathy in general is benign and does not cause relevant congestive heart failure and subsides with treatment. We review the differences between the American and African trypanosomiasis with the main focus on the heart.

Sleeping glands? - The role of endocrine disorders in sleeping sickness (T.b. gambiense Human African Trypanosomiasis)

Symptoms consistent with hypothyroidism or adrenal insufficiency, such as lethargy, anorexia, cold intolerance, weakness, hypotension or paraesthesia, are frequently reported in the literature in patients with Human African Trypanosomiasis (HAT), but an endocrine origin for these symptoms has not yet been demonstrated. Thyroid and adrenocortical function were assessed in 60 patients with late-stage HAT and compared to those in 60 age- and gender-matched healthy controls. Clinical assessment and endocrine laboratory examinations were performed on admission, within 2 days after the end of treatment and at follow-up 3 months later. Signs and symptoms of hypothyroidism, such as fatigue, cold sensation, constipation, paraesthesia, peripheral oedema and dry skin, were significantly more frequent in HAT patients than in the controls. However, these signs and symptoms could not be attributed to hypothyroidism due to the lack of supporting laboratory data, and thus empirical replacement therapy for the clinically suspected hypothyroidism was not warranted. Signs and symptoms consistent with adrenal insufficiency, such as weakness, anorexia, weight loss or hypotension, were significantly more frequent in HAT patients than in controls, but they could not be associated with an insufficiency of the adrenocortical axis. Higher basal levels of cortisol were found in HAT patients than in controls, which can be viewed as a stress response to the infection. However, a transitory adrenal insufficiency was suspected in 8% of HAT patients at admission and in 9% at discharge. All values were normal at follow-up 3 months later.