Geographical structuring of Trypanosoma cruzi populations from Chilean Triatoma infestans triatomines and their genetic relationship with other Latino American counterparts.

In order to obtain more information about the population structure of Chilean Trypanosoma cruzi, and their genetic relationship with other Latino American counterparts, we performed the study of T. cruzi samples detected in the midgut content of Triatoma infestans insects from three endemic regions of Chile. The genetic characteristics of these samples were analysed using microsatellite markers and PCR conditions that allow the detection of predominant T. cruzi clones directly in triatomine midgut content. Population genetic analyses using the Fisher's exact method, analysis of molecular variance (AMOVA) and the determination of F(ST) showed that the northern T. cruzi population sample was genetically differentiated from the two southern population counterparts. Further analysis showed that the cause of this genetic differentiation was the asymmetrical distribution of TcIII T. cruzi predominant clones. Considering all triatomines from the three regions, the most frequent predominant lineages were TcIII (38%), followed by TcI (34%) and hybrid (8%). No TcII lineage was observed along the predominant T. cruzi clones. The best phylogenetic reconstruction using the shared allelic genetic distance was concordant with the population genetic analysis and tree topology previously described studying foreign samples. The correlation studies showed that the lineage TcIII from the III region was genetically differentiated from the other two, and this differentiation was correlated with geographical distance including Chilean and mainly Brazilian samples. It will be interesting to investigate whether this geographical structure may be related with different clinical manifestation of Chagas disease.

Human pseudoterranovosis, an emerging infection in Chile.

Fifteen cases of human pseudoterranovosis are reported for Chile, representing an emerging parasitic infection in this country caused by larvae of the nematode Pseudoterranova sp. Our observations also included an outbreak of pseudoterranovosis in 3 of 4 individuals who shared the same raw fish dish (cebiche). Most of the cases occurred in adult patients. The main source of infection was from consumption raw or fried marine fish, including hakes (Merluccius australis or Merlucciuts gayi), pomfret (Brama australis), Inca scad (Trachurus murphvi), and corvina (Cilus gilberti). Seasonal distribution showed most of the cases to occur in fall and spring. Parasite larvae were isolated from the mouths of most of the patients after they reported a pharyngeal tickling sensation, coughing, vomiting, or a foreign body in the mouth or throat.

Microsatellite loci-based distribution of Trypanosoma cruzi genotypes from Chilean chronic Chagas disease patients and Triatoma infestans is concordant with a specific host-parasite association hypothesis.

The objective of this study was to investigate if there is specific host-parasite association in Chilean populations of Trypanosoma cruzi. For this purpose, two groups of parasites were analyzed, one from chronic chagasic patients, and the other from Triatoma infestans triatomines in three regions of the country. The first group consisted of four types of samples: parasites from peripheral blood of non-cardiopathic T. cruzi infected patients (NB); parasites from their corresponding xenodiagnosis (NX); parasites from peripheral blood of T. cruzi infected cardiopathic patients (CB) and parasites from their xenodiagnostics (CX). The T. infestans sample in turn was from three regions: III, V and M (Metropolitan). The genetic differentiation by the Fisher exact method, the lineage distribution of the samples, the molecular phylogeny and the frequency of multiclonality were analysed. The results show that not only are the groups of T. cruzi clones from Chagas disease patients and vectors genetically differentiated, but also all the sub-groups (NB, NX, CB and CX) from the III, V and M regions. The analysis of lineage distribution was concordant with the above results, because significant differences among the percentages of TcI, TcIII and hybrids (TcV or TcVI) were observed. The phylogenetic reconstruction with these Chilean T. cruzi samples was coherent with the above results because the four chagasic samples clustered together in a node with high bootstrap support, whereas the three triatomine samples (III, V and M) were located apart from that node. The topology of the tree including published T. cruzi clones and isolates was concordant with the known topology, which confirmed that the results presented here are correct and are not biased by experimental error. Taken together the results presented here are concordant with a specific host-parasite association between some Chilean T. cruzi populations.

Acute fascioliasis--clinical and epidemiological features of four patients in Chile.

Because of its infrequent and protean presentation and the lack of clinical data, the management of acute infections with the foodborne trematode Fasciola hepatica is challenging. We report four serologically confirmed cases that illustrate our experience with this parasitic infection in Chile. All patients were adults presenting with upper abdominal pain. Other symptoms included fever, nausea/vomiting, and cutaneous manifestations. In all cases, marked eosinophilia was present. All patients lived in an urban environment, and three reported the consumption of raw watercress. Computed tomography (CT) scans showed hypodense hepatic lesions, whereas ultrasonography findings were unremarkable. One patient suffered portal vein thrombosis, which might be a rare complication of acute fascioliasis. All patients were successfully treated with triclabendazole. Our case series demonstrates that patients with acute fascioliasis typically present with a combination of upper abdominal pain, marked eosinophilia, and hypodense hepatic lesions on CT imaging. Diagnosis should be confirmed by serological investigation. A history of recent consumption of raw watercress is an important finding, but in some patients the source of infection remains obscure.

Inmunodiagnóstico de las infecciones por Strongloides stercoralis en Chile utilizando la prueba de ELISA / Immunodiagnosis of Strongyloides stercoralis infections in Chile using ELISA test

BACKGROUND: Strongyloides stercoralis is a world wide distributed small intestinal nematode parasite. In immunocompetent individuals S stercoralis can produce asymptomatic infections or a moderate clinical picture of diarrhea, some cases become chronic. In immunocompromised patients, a disseminated disease may appear, sometimes fatal. In Chile, there is little epidemiological information about S stercoralis infections and appropriate diagnostic techniques are usually not used. AIM: To evaluate the yield of an ELISA test for the diagnosis of strongyloidiasis in Chilean patients. MATERIAL AND METHODS: Ten serum samples from patients with S stercoralis infections confirmed by a positive stool examination, 66 samples from individuals with other infections by tissue helminthes (24 toxocariasis, 15 trichinellosis, 11 hydatidosis, 12 fascioliasis and 4 cysticercosis), 13 samples from subjects with autoimmune diseases and 49 samples from apparently healthy individuals with a normal eosinophil count, were studied. ELISA antigen was prepared using a filariform larval extract obtained from a murine species of Strongyloides, maintained in laboratory animals. RESULTS: Using 0.33 optical density units as a cut off value, 9 of 10 sera of S stercoralis infected individuals, had a positive ELISA test. No cross reactions were observed with sera of patients with other helminthic infections, autoimmune diseases or in healthy individuals. Thus, specificity, positive and negative predictive values were 100 per cent. CONCLUSIONS: The results obtained are similar with those found by other investigators. ELISA test for strongyloidiasis is a useful tool for the diagnosis of clinical cases and for seroepidemiological studies of this nematode infection in Chile.

Estudio clínico y determinación de la parasitemia en un grupo de pacientes infectados por Trypanosoma cruzi de la región de Atacama, Chile / Clinical study of measure of parasitemia in patients infected with Trypanosoma cruzi in Atacama, Chile

BACKGROUND: Trypanosoma cruzi infection is endemic in Northern/Central Chile. AIM: To perform a clinical assessment of patients infected with Trypanosoma cruzi. PATIENTS AND METHODS: Two hundred sixty three subjects with a positive serology for Trypanosoma cruzi, were invited by mail to a clinical assessment in a Regional Hospital. In a subsample of these, a polymerase chain reaction for Trypanosoma cruzi, was done. RESULTS: Of all the invited subjects, 183 responded and were assessed at the hospital. Of these, 60 had cardiac affections, 52 had colon problems and 17, esophageal disease. Seventy four were asymptomatic. Of the 64 patients in whom polymerase chain reaction was done, 35 had a positive result. CONCLUSIONS: A high percentage of subjects infected with Trypanosoma cruzi, had clinical consequences of the infection. Polymerase chain reaction showed persistency of the parasite in more than half of the infected patients.