Louis V. Kirchhoff

Canine Visceral Leishmaniasis, United States and Canada, 2000-2003

Foxhounds infected with Leishmania spp. were found in 18 states and 2 Canadian provinces.

Perspectives on Trypanosoma cruzi–Induced Heart Disease (Chagas Disease)

Chagas disease is caused by the parasite Trypanosoma cruzi. It is a common cause of heart disease in endemic areas of Latin America. The year 2009 marks the 100th anniversary of the discovery of T cruzi infection and Chagas disease by the Brazilian physician Carlos Chagas. Chagasic cardiomyopathy develops in from 10% to 30% of persons who are chronically infected with this parasite. Echocardiography and magnetic resonance imaging (MRI) are important modalities in the evaluation and prognostication of individuals with chagasic heart disease. The etiology of chagasic heart disease likely is multifactorial. Parasite persistence, autoimmunity, and microvascular abnormalities have been studied extensively as possible pathogenic mechanisms. Experimental studies suggest that alterations in cardiac gap junctions may be etiologic in the pathogenesis of conduction abnormalities. The diagnosis of chronic Chagas disease is made by serology. The treatment of this infection has shortcomings that need to be addressed. Cardiac transplantation and bone marrow stem cell therapy for persons with Chagas disease have received increasing research attention in recent years.

Seroepidemiology of Trypanosoma cruzi, Etiologic Agent of Chagas' Disease, in US Blood Donors

A comprehensive seroepidemiologic study was conducted in two Red Cross regions (Los Angeles and Miami) to determine the prevalence of Trypanosoma cruzi antibodies in at-risk blood donors, to identify additional risk factors, and to assess the likelihood of transmitting T. cruzi by transfusion. At-risk and control donors were stratified by a broad risk question, tested for T. cruzi antibodies, and if confirmed as seropositive, enrolled in case-control and lookback investigations. A total of 299,398 donors were queried; 23,978 at-risk and 25,587 control donations were tested, and T. cruzi antibodies were confirmed in 34 donors (33 and 1, respectively). Seropositive donors shared one risk factor; birth/extensive time in a T. cruzi-endemic area. Lookback studies identified 11 recipients, all negative for T. cruzi antibodies. Screening strategies that use a question are unlikely to identify all seropositive donors. The lack of definitive data on the risk of transmission by transfusion indicates additional studies of donors and recipients are needed.

WHO comparative evaluation of serologic assays for Chagas disease

BACKGROUND: Evaluation of commercially available test kits for Chagas disease for use in blood bank screening is difficult due to a lack of large and well‐characterized specimen panels. This study presents a collaborative effort of Latin American blood centers and the World Health Organization (WHO) to establish such a panel.

Post-transcriptional Elements Regulating Expression of mRNAs from the Amastin/Tuzin Gene Cluster of Trypanosoma cruzi

The genome of Trypanosoma cruzi contains tandemly arrayed copies of the gene encoding amastin, an abundant protein on the surface of the amastigote stage of the parasite. The transcription rate of the amastin genes is the same in the different developmental stages, but the steady state level of the 1.4-kilobase amastin mRNA is 50-85 times higher in amastigotes than in epimastigotes or trypomastigotes(1). Here we show that the amastin genes alternate with genes encoding another protein, called tuzin, whose 1.7-kilobase mRNA is much less abundant in amastigotes. The 3′-untranslated region (UTR) of tuzin mRNA is only a few nucleotides in length or even nonexistent, in contrast with the 630-nucleotide 3′-UTR of amastin mRNA. No promoter elements were found upstream or within the amastin/tuzin gene cluster. However, in amastigotes, the protein synthesis inhibitor cycloheximide caused a 3-fold decrease in amastin mRNA and a 7-fold increase in tuzin mRNA. Furthermore, when the amastin 3′-UTR plus its downstream intergenic region were fused behind the luciferase coding region in a chimeric plasmid for transient transfections, luciferase activity increased 7-fold in amastigotes and decreased 5-fold in epimastigotes. Thus, developmental expression of these alternating genes is regulated by different mechanisms.

Molecular cloning of mtp70, a mitochondrial member of the hsp70 family.

We have isolated a gene from the protozoan parasite Trypanosoma cruzi that encodes a previously unidentified member of the 70-kilodalton heat shock protein (hsp70) family. Among all the eucaryotic hsp70 proteins described to date, this trypanosome protein, mtp70, is uniquely related in sequence and structure to the hsp70 of Escherichia coli, DnaK, which functions in the initiation of DNA replication. This relationship to DnaK is especially relevant in view of the intracellular location of the protein. Within the trypanosome, mtp70 is located in the mitochondrion, where it associates with kinetoplast DNA (kDNA), the unusual mitochondrial DNA that distinguishes this order of protozoa. Moreover, mtp70 is located in the specific region of the kinetoplast in which kDNA replication occurs. In view of the known functions of DnaK, the localization of mtp70 to the site of kDNA replication suggests that mtp70 may participate in eucaryotic mitochondrial DNA replication in a manner analogous to that of DnaK in E. coli.

Trypanosoma cruzi exhibits inter- and intra-strain heterogeneity in molecular karyotype and chromosomal gene location

Molecular karyotypes of 6 strains and 6 clones of Trypanosoma cruzi were determined using orthogonal-field-alternation gel electrophoresis. At least 15 different chromosome-sized DNA molecules, ranging in size from less than 200 kilobase pairs to greater than 2000 kilobase pairs, were resolved for each of the isolates examined. Many of the bands were present in different relative intensities suggesting that the number of individual chromosomes per organism may be considerably higher. Significant inter- and intra-strain differences in molecular karyotype and in the chromosomal locations of the genes for the spliced leader, tubulins, 5S ribosomal RNA and a heat shock protein were found. These marked chromosomal differences among T. cruzi strains and clones may be related to the high degree of phenotypic heterogeneity previously found in this parasite.

Transfusion‐associated Chagas disease (American trypanosomiasis) in Mexico: implications for transfusion medicine in the United States

BACKGROUND:  Trypanosoma cruzi, the protozoan cause of Chagas disease, causes life‐long infection and is easily transmitted by blood transfusion. Our goals were to determine the prevalence of Chagas disease among donors in five Mexican blood banks, to look for evidence of transmission of T. cruzi by transfusion, and to evaluate two serologic assays for Chagas disease.

Evaluation of a prototype Trypanosoma cruzi antibody assay with recombinant antigens on a fully automated chemiluminescence analyzer for blood donor screening

BACKGROUND: Chagas disease is caused by Trypanosoma cruzi, a protozoan parasite that can be transmitted by transfusion. The diagnosis of chronic T. cruzi infection is generally made by detecting specific antibodies that bind to parasite antigens. The aim of this study was to assess the sensitivity and specificity of a new serologic assay for antibodies to T. cruzi on a fully automated analyzer (PRISM, Abbott Laboratories).

Chagas Heart Disease: Report on Recent Developments

Chagas disease, caused by the parasite Trypanosoma cruzi, is an important cause of cardiac disease in endemic areas of Latin America. It is now being diagnosed in nonendemic areas because of immigration. Typical cardiac manifestations of Chagas disease include dilated cardiomyopathy, congestive heart failure, arrhythmias, cardioembolism, and stroke. Clinical and laboratory-based research to define the pathology resulting from T. cruzi infection has shed light on many of the cellular and molecular mechanisms leading to these manifestations. Antiparasitic treatment may not be appropriate for patients with advanced cardiac disease. Clinical management of Chagas heart disease is similar to that used for cardiomyopathies caused by other processes. Cardiac transplantation has been successfully performed in a small number of patients with Chagas heart disease.