Clinical analysis and parasite genetic diversity in human immunodeficiency virus/Chagas' disease coinfections in Brazil

Chagas disease in the immunocompromised host

PURPOSE OF REVIEW

To highlight recent advances in our understanding of Trypanosoma cruzi infection in immunocompromised individuals, a condition that is increasingly recognized as populations shift and use of immunosuppressive medications becomes more commonplace.

RECENT FINDINGS

Chagas disease screening programs should include people at risk for both Chagas disease and immunocompromise, e.g. people who have resided for ≥6 months in endemic Latin America who have an immunocompromising condition such as HIV or who are planned to start an immunosuppressive medication regimen. The goal of identifying such individuals is to allow management strategies that will reduce their risk of T. cruzi reactivation disease. For people with HIV-T. cruzi coinfection, strict adherence to antiretroviral therapy is important and antitrypanosomal treatment is urgent in the setting of symptomatic reactivation. People at risk for T. cruzi reactivation due to immunosuppression caused by advanced hematologic conditions or postsolid organ transplantation should be monitored via T. cruzi qPCR and treated with preemptive antitrypanosomal therapy if rising parasite load on serial specimens indicates reactivation. Reduction of the immunosuppressive regimen, if possible, is important.

SUMMARY

Chronic Chagas disease can lead to severe disease in immunocompromised individuals, particularly those with advanced HIV (CD4+ < 200 cells/mm3) or peri-transplantation.

Chagas disease in immunocompromised patients

SUMMARYAs Chagas disease remains prevalent in the Americas, it is important that healthcare professionals and researchers are aware of the screening, diagnosis, monitoring, and treatment recommendations for the populations of patients they care for and study. Management of Trypanosoma cruzi infection in immunocompromised hosts is challenging, particularly because, regardless of antitrypanosomal treatment status, immunocompromised patients with Chagas disease are at risk for T. cruzi reactivation, which can be lethal. Evidence-based practices to prevent and manage T. cruzi reactivation vary depending on the type of immunocompromise. Here, we review available data describing Chagas disease epidemiology, testing, and management practices for various populations of immunocompromised individuals, including people with HIV and patients undergoing solid organ and hematopoietic stem cell transplantation.

New insights into Trypanosoma cruzi genetic diversity, and its influence on parasite biology and clinical outcomes

Chagas disease, caused by Trypanosoma cruzi, remains a serious public health problem worldwide. The parasite was subdivided into six distinct genetic groups, called "discrete typing units" (DTUs), from TcI to TcVI. Several studies have indicated that the heterogeneity of T. cruzi species directly affects the diversity of clinical manifestations of Chagas disease, control, diagnosis performance, and susceptibility to treatment. Thus, this review aims to describe how T. cruzi genetic diversity influences the biology of the parasite and/or clinical parameters in humans. Regarding the geographic dispersion of T. cruzi, evident differences were observed in the distribution of DTUs in distinct areas. For example, TcII is the main DTU detected in Brazilian patients from the central and southeastern regions, where there are also registers of TcVI as a secondary T. cruzi DTU. An important aspect observed in previous studies is that the genetic variability of T. cruzi can impact parasite infectivity, reproduction, and differentiation in the vectors. It has been proposed that T. cruzi DTU influences the host immune response and affects disease progression. Genetic aspects of the parasite play an important role in determining which host tissues will be infected, thus heavily influencing Chagas disease's pathogenesis. Several teams have investigated the correlation between T. cruzi DTU and the reactivation of Chagas disease. In agreement with these data, it is reasonable to suppose that the immunological condition of the patient, whether or not associated with the reactivation of the T. cruzi infection and the parasite strain, may have an important role in the pathogenesis of Chagas disease. In this context, understanding the genetics of T. cruzi and its biological and clinical implications will provide new knowledge that may contribute to additional strategies in the diagnosis and clinical outcome follow-up of patients with Chagas disease, in addition to the reactivation of immunocompromised patients infected with T. cruzi.

Screening for Chagas disease should be included in entry-to-care testing for at-risk people with HIV living in the United States

Chagas disease screening of at-risk populations is essential to identify infected individuals and facilitate timely treatment before end-organ damage occurs. Co-infected people with HIV (PWH) are at risk for dangerous sequelae, specifically Trypanosoma cruzi reactivation disease. Recently published national recommendations indicate that at-risk PWH, particularly those from endemic areas or born to women from endemic areas, should be screened via a sensitive anti-T. cruzi IgG assay. However, immunocompromised patients with negative serologic results may warrant further investigation. Reactivation should be suspected in at-risk, untreated PWH with low CD4 cell counts presenting with acute neurologic or cardiac symptoms; these patients should be promptly evaluated and treated. One pragmatic solution to improve Chagas disease screening among PWH and thereby reduce T. cruzi -related morbidity and mortality is to incorporate Chagas disease screening into the panel of tests routinely performed during the entry-to-care evaluation for at-risk PWH.

Chagas Disease in People with HIV: A Narrative Review

Many questions remain unanswered regarding the epidemiology, pathophysiology, diagnosis, treatment, and monitoring of Trypanosoma cruzi infection in people with HIV (PWH). The reported prevalence of T. cruzi infection in PWH living in endemic countries ranges from 1-28% and is likely similar in at-risk US populations. While classic cardiac and gastrointestinal presentations of chronic Chagas disease occur in PWH, PWH are additionally at risk for a severe and often fatal form of T. cruzi-mediated disease called reactivation disease. T. cruzi reactivation typically occurs in PWH with low CD4 counts and poor virologic control. National HIV guidelines in several endemic South American countries recommend that all PWH be screened for T. cruzi infection at the time of HIV diagnosis; however, this recommendation is not widely implemented. The early detection of T. cruzi infection in PWH is critical as the sequelae of Chagas disease, including T. cruzi reactivation, may be preventable through the restoration of robust cellular immunity via the initiation of antiretroviral therapy and the appropriate use of antitrypanosomal therapy.

Tissue Parasites in HIV Infection

PURPOSE OF REVIEW

The purpose of this review is to discuss the current knowledge of HIV and tissue parasite co-infection in the context of transmission enhancement, clinical characteristics, treatment, relapse, and clinical outcomes.

RECENT FINDINGS

The pathophysiology and clinical sequelae of tissue parasites in people living with HIV (PLWH) have been well described for only a handful of organisms, primarily protozoa such as malaria and leishmaniasis. Available published data indicate that the interactions between HIV and tissue parasites are highly variable depending on the infecting organism and the degree of host immunosuppression. Some tissue parasites, such as Schistosoma species, are known to facilitate the transmission of HIV. Conversely, uncontrolled HIV infection can lead to the earlier and more severe presentation of a variety of tissue parasites and can make treatment more challenging. Although much investigation remains to be done to better understand the interactions between consequences of HIV and tissue parasite co-infection, it is important to disseminate the current knowledge on this topic to health care providers in order to prevent, treat, and control infections in PLWH.

Astrocyte Apoptosis and HIV Replication Are Modulated in Host Cells Coinfected with Trypanosoma cruzi

The protozoan Trypanosoma cruzi is the etiological agent of Chagas disease. In immunosuppressed individuals, as it occurs in the coinfection with human immunodeficiency virus (HIV), the central nervous system may be affected. In this regard, reactivation of Chagas disease is severe and often lethal, and it accounts for meningoencephalitis. Astrocytes play a crucial role in the environment maintenance of healthy neurons; however, they can host HIV and T. cruzi. In this report, human astrocytes were infected in vitro with both genetically modified-pathogens to express alternative fluorophore. As evidenced by fluorescence microscopy and flow cytometry, HIV and T. cruzi coexist in the same astrocyte, likely favoring reciprocal interactions. In this context, lower rates of cell death were observed in both T. cruzi monoinfected-astrocytes and HIV-T. cruzi coinfection in comparison with those infected only with HIV. The level of HIV replication is significantly diminished under T. cruzi coinfection, but without affecting the infectivity of the HIV progeny. This interference with viral replication appears to be related to the T. cruzi multiplication rate or its increased intracellular presence but does not require their intracellular cohabitation or infected cell-to-cell contact. Among several Th1/Th2/Th17 profile-related cytokines, only IL-6 was overexpressed in HIV-T. cruzi coinfection exhibiting its cytoprotective role. This study demonstrates that T. cruzi and HIV are able to coinfect astrocytes thus altering viral replication and apoptosis.

Reactivation of Chagas Disease: Implications for Global Health

Reactivation of Chagas Disease (CD) is a global public health issue. Reactivation of disease can affect the management of CD and its clinical outcome, adding pressure to global health systems because it exacerbates symptoms, leading to misdiagnosis and delays in the administration of correct treatments. Concurrent infections complicate the issue of reactivation, because there are various parasites and disease treatment regimens that are able to influence or suppress the immune system of the host, reactivating disease within infected individuals. The effect of delayed symptoms of chronic CD and the potential for disease reactivation are of great importance to nonendemic regions of the world, where knowledge about CD is lacking and the potential for vectorial transmission is not known.

Between a bug and a hard place: Trypanosoma cruzi genetic diversity and the clinical outcomes of Chagas disease

Over the last 30 years, concomitant with successful transnational disease control programs across Latin America, Chagas disease has expanded from a neglected, endemic parasitic infection of the rural poor to an urbanized chronic disease, and now a potentially emergent global health problem. Trypanosoma cruzi infection has a highly variable clinical course, ranging from complete absence of symptoms to severe and often fatal cardiovascular and/or gastrointestinal manifestations. To date, few correlates of clinical disease progression have been identified. Elucidating a putative role for T. cruzi strain diversity in Chagas disease pathogenesis is complicated by the scarcity of parasites in clinical specimens and the limitations of our contemporary genotyping techniques. This article systematically reviews the historical literature, given our current understanding of parasite genetic diversity, to evaluate the evidence for any association between T. cruzi genotype and chronic clinical outcome, risk of congenital transmission or reactivation and orally transmitted outbreaks.

Trypanosoma cruzi necrotizing meningoencephalitis in a Venezuelan HIV⁺-AIDS patient: pathological diagnosis confirmed by PCR using formalin-fixed- and paraffin-embedded-tissues

Coinfections with human immunodeficiency virus (HIV) and infectious agents have been recognized since the early 90s. In the central nervous system (CNS) of HIV⁺ patients, parasitic protozoans like Toxoplasma gondii have been described as responsible for the space occupying lesions (SOL) developed. However, the involvement of Trypanosoma cruzi is also described but appears to be less frequent in acquired immunodeficiency syndrome (AIDS) and transplant recipients, associated with necrotizing myocarditis and neurological symptoms related to the occurrence of necrotizing pseudotumoral encephalitis (NPE) and meningoencephalitis (NME). The present work aims to present a Venezuelan case of NME associated with the coinfection of HIV and a T. cruzi-like trypanosomatid as well as its evolution and diagnosis by histopathological techniques, electron microscopy, and PCR methods using formalin-fixed- (FF-) and paraffin-embedded- (PE-) tissues. Postmortem cytological studies of leptomeninges imprints reveal the presence of trypomastigotes of Trypanosoma sp. Histopathological and electron microscopy studies allowed us to identify an amastigote stage and to reject the involvement of other opportunistic microorganisms as the etiological agent of the SOL. The definitive confirmation of T. cruzi as the etiological agent was achieved by PCR suggesting that the NME by T. cruzi was due to a reactivation of Chagas' disease.

Immunosuppression and Chagas disease: a management challenge

Immunosuppression, which has become an increasingly relevant clinical condition in the last 50 years, modifies the natural history of Trypanosoma cruzi infection in most patients with Chagas disease. The main goal in this setting is to prevent the consequences of reactivation of T. cruzi infection by close monitoring. We analyze the relationship between Chagas disease and three immunosuppressant conditions, including a description of clinical cases seen at our center, a brief review of the literature, and recommendations for the management of these patients based on our experience and on the data in the literature. T. cruzi infection is considered an opportunistic parasitic infection indicative of AIDS, and clinical manifestations of reactivation are more severe than in acute Chagas disease. Parasitemia is the most important defining feature of reactivation. Treatment with benznidazole and/or nifurtimox is strongly recommended in such cases. It seems reasonable to administer trypanocidal treatment only to asymptomatic immunosuppressed patients with detectable parasitemia, and/or patients with clinically defined reactivation. Specific treatment for Chagas disease does not appear to be related to a higher incidence of neoplasms, and a direct role of T. cruzi in the etiology of neoplastic disease has not been confirmed. Systemic immunosuppressive diseases or immunosuppressants can modify the natural course of T. cruzi infection. Immunosuppressive doses of corticosteroids have not been associated with higher rates of reactivation of Chagas disease. Despite a lack of evidence-based data, treatment with benznidazole or nifurtimox should be initiated before immunosuppression where possible to reduce the risk of reactivation. Timely antiparasitic treatment with benznidazole and nifurtimox (or with posaconazole in cases of therapeutic failure) has proven to be highly effective in preventing Chagas disease reactivation, even if such treatment has not been formally incorporated into management protocols for immunosuppressed patients. International consensus guidelines based on expert opinion would greatly contribute to standardizing the management of immunosuppressed patients with Chagas disease.

Co-infection Trypanosoma cruzi/HIV: systematic review (1980-2010)

INTRODUCTION

The co-infection Trypanosoma cruzi/HIV has been described as a clinical event of great relevance. The objective of this study was to describe clinical and epidemiological aspects published in literature.

METHODS

It is a systematic review of a descriptive nature from the databases Medline, Lilacs, SciELO, Scopus, from 1980 to 2010.

RESULTS

There were 83 articles (2.8 articles/year) with a total of 291 cases. The co-infection was described in 1980 and this situation has become the defining AIDS clinical event in Brazil. This is the country with the highest number of publication (51.8%) followed by Argentina (27.7%). The majority of cases are amongst adult men (65.3%) native or from endemic regions with serological diagnosis in the chronic stage (97.9%) and indeterminate form (50.8%). Both diseases follow the normal course, but in 41% the reactivation of the Chagas disease occurs. The most severe form is the meningoencephalitis, with 100% of mortality without specific and early treatment of the T. cruzi. The medication of choice was the benznidazole on doses and duration normally used for the acute phase. The high parasitemia detected by direct or indirect quantitative methods indicated reactivation and its elevation is the most important predictive factor. The lower survival rate was related to the reactivation of the Chagas disease and the natural complications of both diseases. The role of the antiretroviral treatment on the co-infection cannot yet be defined by the knowledge currently existent.

CONCLUSIONS

Despite the relevance of this clinical event there are still gaps to be filled.

Guidelines on the treatment of chronic coinfection by Trypanosoma cruzi and HIV outside endemic areas

As a result of population migration, Chagas disease is no longer limited to the North and South American continents. In HIV-infected patients, chronic infection by Trypanosoma cruzi behaves as an opportunistic infection in severely immunosuppressed patients and is responsible for high morbidity and mortality. Unlike other opportunistic infections, information on the natural history, diagnosis, treatment, and prevention of Chagas disease is scarce. Spain has the highest number of cases of Chagas disease outside the North and South American continents, and coinfection with HIV is increasingly prevalent. In this article, the Spanish Society for Tropical Medicine and International Health (Sociedad Española de Medicina Tropical y Salud Internacional) reviews the current situation of coinfection with HIV and T. cruzi infection and provides guidelines on the diagnosis, treatment, and prevention in areas where Chagas disease is not endemic. It also identifies areas of uncertainty where additional research is necessary.

Real-time PCR in HIV/Trypanosoma cruzi coinfection with and without Chagas disease reactivation: association with HIV viral load and CD4 level

BACKGROUND

Reactivation of chronic Chagas disease, which occurs in approximately 20% of patients coinfected with HIV/Trypanosoma cruzi (T. cruzi), is commonly characterized by severe meningoencephalitis and myocarditis. The use of quantitative molecular tests to monitor Chagas disease reactivation was analyzed.

METHODOLOGY

Polymerase chain reaction (PCR) of kDNA sequences, competitive (C-) PCR and real-time quantitative (q) PCR were compared with blood cultures and xenodiagnosis in samples from 91 patients (57 patients with chronic Chagas disease and 34 with HIV/T. cruzi coinfection), of whom 5 had reactivation of Chagas disease and 29 did not.

PRINCIPAL FINDINGS

qRT-PCR showed significant differences between groups; the highest parasitemia was observed in patients infected with HIV/T. cruzi with Chagas disease reactivation (median 1428.90 T. cruzi/mL), followed by patients with HIV/T. cruzi infection without reactivation (median 1.57 T. cruzi/mL) and patients with Chagas disease without HIV (median 0.00 T. cruzi/mL). Spearman's correlation coefficient showed that xenodiagnosis was correlated with blood culture, C-PCR and qRT-PCR. A stronger Spearman correlation index was found between C-PCR and qRT-PCR, the number of parasites and the HIV viral load, expressed as the number of CD4(+) cells or the CD4(+)/CD8(+) ratio.

CONCLUSIONS

qRT-PCR distinguished the groups of HIV/T. cruzi coinfected patients with and without reactivation. Therefore, this new method of qRT-PCR is proposed as a tool for prospective studies to analyze the importance of parasitemia (persistent and/or increased) as a criterion for recommending pre-emptive therapy in patients with chronic Chagas disease with HIV infection or immunosuppression. As seen in this study, an increase in HIV viral load and decreases in the number of CD4(+) cells/mm(3) and the CD4(+)/CD8(+) ratio were identified as cofactors for increased parasitemia that can be used to target the introduction of early, pre-emptive therapy.

Benznidazole alters the pattern of Cyclophosphamide-induced reactivation in experimental Trypanosoma cruzi-dependent lineage infection

The factors involved in the reactivation of chronic Chagas disease infection are not clear enough and may be related to host immune unbalance and/or parasite genetic diversity. To evaluate the role of the Trypanosoma cruzi genetic background in the Chagas disease reactivation, we inoculated Cyclophosphamide-immunosupressed (CyI) Swiss mice with clonal stocks from T. cruzi I (Cuica cl1, P209 cl1, Gamba cl1, SP104 cl1), T. cruzi II (IVV cl4, MVB cl8) and T. cruzi (Bug2148 cl1, MN cl2) lineages. We used the parasitemia as the parameter for Chagas disease reactivation and observed that CyI animals infected with T. cruzi stocks showed no reactivation and those infected with T. cruzi II stocks showed only 5% of reactivation. In contrast, immunosuppressed mice infected with stocks from T. cruzi I lineage showed 77.5 and 51.25% reactivation of the infection when Cyclophosphamide treatment was performed 60 and 180 days after inoculation, respectively. Next, we evaluated the efficacy of the Benznidazole (Bz) pre-treatment in reducing or preventing the recurrence of the infection in these CyI animals. In general, the percentage of the parasite recurrence was not altered among the CyI mice that received the Bz pre-treatment during the acute phase of the infection. Interestingly, when pre-Bz treatment was performed during the chronic phase, we observed two different patterns of response: (i) an increased protection among the animals inoculated with the SP104 cl1 (genotype 19) and Cuica cl1 (genotype 20) stocks; (ii) an increased percentage of parasitemia reactivation among mice inoculated with Gamba cl1 (genotype 19) and P209 cl1 (genotype 20) T. cruzi stocks. Our results corroborate our hypothesis by showing that the T. cruzi genetic background in combination with specific Bz treatment has an important role in the Chagas disease reactivation in immunosuppressed animals.

Inhibition of HIV-1 replication in human monocyte-derived macrophages by parasite Trypanosoma cruzi

BACKGROUND

Cells of monocyte/macrophage lineage are one of the major targets of HIV-1 infection and serve as reservoirs for viral persistence in vivo. These cells are also the target of the protozoa Trypanosoma cruzi, the causative agent of Chagas disease, being one of the most important endemic protozoonoses in Latin America. It has been demonstrated in vitro that co-infection with other pathogens can modulate HIV replication. However, no studies at cellular level have suggested an interaction between T. cruzi and HIV-1 to date.

METHODOLOGY/PRINCIPAL FINDINGS

By using a fully replicative wild-type virus, our study showed that T. cruzi inhibits HIV-1 antigen production by nearly 100% (p<0.001) in monocyte-derived macrophages (MDM). In different infection schemes with luciferase-reporter VSV-G or BaL pseudotyped HIV-1 and trypomastigotes, T. cruzi induced a significant reduction of luciferase level for both pseudotypes in all the infection schemes (p<0.001), T. cruzi-HIV (>99%) being stronger than HIV-T. cruzi (approximately 90% for BaL and approximately 85% for VSV-G) infection. In MDM with established HIV-1 infection, T. cruzi significantly inhibited luciferate activity (p<0.01). By quantifying R-U5 and U5-gag transcripts by real time PCR, our study showed the expression of both transcripts significantly diminished in the presence of trypomastigotes (p<0.05). Thus, T. cruzi inhibits viral post-integration steps, early post-entry steps and entry into MDM. Trypomastigotes also caused a approximately 60-70% decrease of surface CCR5 expression on MDM. Multiplication of T. cruzi inside the MDM does not seem to be required for inhibiting HIV-1 replication since soluble factors secreted by trypomastigotes have shown similar effects. Moreover, the major parasite antigen cruzipain, which is secreted by the trypomastigote form, was able to inhibit viral production in MDM over 90% (p<0.01).

CONCLUSIONS/SIGNIFICANCE

Our study showed that T. cruzi inhibits HIV-1 replication at several replication stages in macrophages, a major cell target for both pathogens.

Interactions among co-infecting parasite species: a mechanism maintaining genetic variation in parasites?

Individuals of free-living organisms are often infected simultaneously by a community of parasites. If the co-infecting parasites interact, then this can add significantly to the diversity of host genotypexparasite genotype interactions. However, interactions between parasite species are usually not examined considering potential variation in interactions between different strain combinations of co-infecting parasites. Here, we examined the importance of interactions between strains of fish eye flukes Diplostomum spathaceum and Diplostomum gasterostei on their infectivity in naive fish hosts. We assessed the infection success of strains of both species in single-strain exposures and in co-exposures with a random strain of the other species. Parasite infection success did not consistently increase or decrease in the co-exposure treatment, but depended on the combinations of co-infecting parasite strains. This disrupted the relative infectivity of D. spathaceum strains observed in single-strain exposures. The infection success of D. gasterostei strains was independent of exposure type. These results suggest that interactions among parasite species may be strain specific and potentially promote maintenance of genetic polymorphism in parasite populations.

Chagasic encephalitis in HIV patients: common presentation of an evolving epidemiological and clinical association

We present a case of chagasic meningoencephalitis reactivation in an HIV-infected woman with advanced immunosuppression. Prolonged survival was attained with antiparasitic therapy and secondary prophylaxis, in conjunction with the use of highly-active antiretroviral therapy. The geographic expansion of the HIV epidemic around the world coupled with global migration and international travel have created a favourable situation for Trypanosoma cruzi and HIV coinfection. The clinical manifestations of Chagas disease in HIV-positive people usually represent reactivation and not acute infection with T cruzi (coinfection). Symptomatic reactivation of chronic latent T cruzi infection can be triggered by severe immunosuppression associated with HIV infection. In this setting, Chagas disease reactivation often presents as meningoencephalitis resembling toxoplasma encephalitis. We review, in this Grand Round, the clinical manifestations, diagnostic approach, pathogenesis, natural history, treatment, prognosis, and prevention of Chagas disease reactivation among HIV-infected people with an emphasis on CNS manifestations.

New potent 5-substituted benzofuroxans as inhibitors of Trypanosoma cruzi growth: Quantitative structure–activity relationship studies

Benzofuroxan derivatives have been shown to inhibit the growth of Trypanosoma cruzi, the etiological agent of Chagas' disease. Therefore, 2D- and 3D-QSAR models of their in vitro antichagasic activity were developed. Six new derivatives were synthesized to complete a final set of 26 structurally diverse benzofuroxans. The 2D-QSAR model (r = 0.939, r(adj)(2) = 0.849) was generated using multiple regression analysis of tabulated substituents' physicochemical properties and indicator variables. In addition, a 3D-QSAR model (r(2) = 0.997, q(2) = 0.802) was obtained using a comparative molecular field analysis (CoMFA). Due to the well-known benzofuroxan tautomerism, in both approaches (2D- and 3D-QSAR) it was necessary to include an indicator variable to consider the N-oxide position (I(6)). This parameter was established using low-temperature NMR experiments. Both QSAR models identified the electrophilic character of the substituent alpha-atom as a requirement for activity. Further support was found using a density functional theory (DFT) approach.

The impact of HIV infection on tropical diseases

HIV and tropical infections affect each other mutually. HIV infection may alter the natural history of tropical infectious diseases, impede rapid diagnosis, or reduce the efficacy of antiparasitic treatment. Tropical infections may facilitate the transmission of HIV and accelerate progression from asymptomatic HIV infection to AIDS. This article reviews data on known interactions for malaria, leishmaniasis, human African trypanosomiasis, Chagas' disease, schistosomiasis, onchocerciasis, lymphatic filariasis, and intestinal helminthiases.

Long-term follow-up of co-infected HIV and Trypanosoma cruzi Brazilian patients

Three cases of Trypanosoma cruzi-HIV co-infected haemophiliacs are described. Parasitological (xenodiagnosis, haemoculture, PCR) and immunological (CD4+ and CD8+ T cell counts, in vitro lymphoproliferative responses) studies were performed. Hybridization of isolated parasites with a specific probe confirmed the T. cruzi aetiology. We observed that despite the high parasitaemia, no clinical or parasitological evidence of T. cruzi reactivation was detected. CD4+ T cells decreased with time in two patients and the lymphocyte proliferative response to T. cruzi was very low in all patients. These data suggest that T. cruzi infection may have a long silent course in immunosuppressed HIV patients. Therefore, this parasitic infection should be investigated in any AIDS patient coming from areas endemic for Chagas' disease.

Chagas' disease and AIDS

Chagas' disease caused by Trypanosoma cruzi is an opportunistic infection in the setting of HIV/AIDS. Some individuals with HIV and chronic T. cruzi infection may experience a reactivation, which is most commonly manifested by meningoencephalitis. A reactivation myocarditis is the second most common manifestation. These presentations may be difficult to distinguish from toxoplasmosis in individuals with HIV/AIDS. The overlap of HIV and Trypanosoma cruzi infection occurs not only in endemic areas but also in non-endemic areas of North America and Europe where the diagnosis may be even more difficult. The pathological features, diagnosis and the role of cytokines in the pathogenesis of the disease are discussed.

Chagas disease and HIV co-infection: genetic analyses of two Trypanosoma cruzi strains under experimental immunosuppression

BACKGROUND: Recently new aspects of the immunopathology of Chagas disease have been described in patients infected with HIV and unusual clinical manifestations such as cutaneous lesions, involvement of central nervous system and/or serious cardiac lesions related to the reactivation of the parasite have been reported. Two uncloned Trypanosoma cruzi strains previously isolated from chronic chagasic patients with HIV co-infection were studied in order to evaluate the impact of the immunosuppression on the genetic diversity of the parasite. RESULTS: We have exploited an experimental model to determine whether genetically distinct populations appear after immunosuppression as a consequence of in vivo selection or in vitro propagation. The in vitro and in vivo conditions have allowed us to study the selected populations. The first strain was isolated from a case of reactivation of Chagas disease in a patient which presented four cerebral lesions. It was possible to demonstrate that the patient was infected with at least three distinct populations of T. cruzi. The population, recovered after immunosuppression, in mice was genetically divergent from the primary human isolate. The second strain, isolated from a hemophiliac/HIV positive patient presenting cardiac manifestation of Chagas disease showed no marked genetic difference after experimental immunosuppression. CONCLUSION: The immunological condition of the patient, associated or not to the reactivation of the infection, and also the strain of the parasite may have an important role during the course of the disease. The in vivo mechanism that generates parasite genetic variability or the participation of the selection under stress conditions will require further investigation.

[Chronic Chagas' disease: from xenodiagnosis and hemoculture to polymerase chain reaction]

Although there has been an improvement in the diagnosis of chronic Chagas' disease, the low sensitivity of indirect parasitological tests is a drawback to its application in diagnosis and post-therapeutic control. Polymerase chain reaction (PCR) has limited use in routine diagnosis due to the need of specific laboratory facilities, common DNA cross-contamination, and high costs. At the same time, the high variability of PCR results found in different regions of Brazil raises some questions concerning its applicability for diagnosis. PCR's high specificity is indicative that it can be used as a confirmation method in inconclusive serology diagnosis as well as an auxiliary method in pos-therapeutic control of chronic Chagas' disease when comparing to serology and parasitological techniques. It is discussed here the applicability of molecular and indirect parasitological methods in the diagnosis and post-therapeutic control of chronic Chagas' disease based on the literature published from 1954 to 2001.

HIV infection and tropical parasitic diseases - deleterious interactions in both directions?

HIV and parasitic infections interact and affect each other mutually. Whereas HIV infection may alter the natural history of parasitic diseases, impede rapid diagnosis or reduce the efficacy of antiparasitic treatment, parasitoses may facilitate the infection with HIV as well as the progression from asymptomatic infection to AIDS. We review data on known interactions for malaria, leishmaniasis, Human African Trypanosomiasis, Chagas' disease, onchocerciasis, lymphatic filariasis, schistosomiasis and intestinal helminthiases. The common immunopathogenetic basis for the deleterious effects parasitic diseases may have on the natural history of HIV infection seems to be a particular type of chronic immune activation and a preferential activation of the T helper (Th)2 type of help. Control of parasitic diseases should complement the tools currently used in combating the HIV pandemic.

Chagasic meningoencephalitis in a patient with acquired immunodeficiency syndrome: diagnosis, follow-up, and genetic characterization of Trypanosoma cruzi

Early diagnosis of the clinical reactivation of Chagas' disease in human immunodeficiency virus- and Trypanosoma cruzi-coinfected persons is fundamental for a good prognosis. Polymerase chain reaction rapidly and efficiently demonstrated the presence and elimination of T. cruzi in the cerebrospinal fluid of a patient with chagasic meningoencephalitis. Characterization of T. cruzi, directly and indirectly in blood and cerebrospinal fluid samples, demonstrated homogeneity of kinetoplast DNA and the presence of lineage 1 (T. cruzi II) in both parasite populations.