Triatomine home invasions in active foci of Chagas disease in Abaetetuba, Pará, Brazil

BACKGROUND

Chagas disease is a parasitic infection with high re-emergence rates in some Amazon regions. The main vectors of Trypanosoma cruzi are haematophagous insects, the triatomines. Only a few reports are available about the occurrence of these wild vectors and their contact with the inhabitants of the riverside regions of the Amazon. This study describes the unusual behaviour of the triatomines that have invaded the homes of the residents of Abaetetuba, the city that has the second highest number of cases of Chagas disease.

METHODS

Two cross-sectional studies were conducted using sero-epidemiological surveys of the inhabitants of Abaetetuba with registered triatomine home invasions. The frequencies of the variables of interest were analysed using Epi Info version 7.2.

RESULTS

In 2014 and 2017, 145 persons registered home invasions of triatomines in their domiciles and 16.55% reported having been bitten by insects. The environmental features described indicated potential conditions for the persistence of the parasite's life cycle. Of the enrolled inhabitants, 0.47% were positive for immunoglobulin G anti-T. cruzi antibodies.

CONCLUSIONS

Home invasions of triatomines were confirmed in two periods, with a description of unusual behaviour for the genus Rhodnius. The use of serological surveillance in human populations at risk of this occurrence may constitute a new tool for the early detection of silent infections.

[Brazilian Consensus on Chagas Disease, 2015]

Chagas disease is a neglected chronic condition that presents high morbidity and mortality burden, with considerable psychological, social, and economic impact. The disease represents a significant public health issue in Brazil, with different regional patterns. This document presents the evidence that resulted in the Brazilian Consensus on Chagas Disease. The objective was to review and standardize strategies for diagnosis, treatment, prevention, and control of Chagas disease in the country, based on the available scientific evidence. The consensus is based on collaboration and contribution of renowned Brazilian experts with vast knowledge and experience on various aspects of the disease. It is the result of close collaboration between the Brazilian Society of Tropical Medicine and the Ministry of Health. This document shall strengthen the development of integrated control measures against Chagas disease in the country, focusing on epidemiology, management, comprehensive care (including families and communities), communication, information, education, and research.

Clinical follow-up of responses to treatment with benznidazol in Amazon: a cohort study of acute Chagas disease

A total of 179 individuals with acute Chagas disease mainly transmitted by oral source, from Pará and Amapá State, Amazonian, Brazil were included during the period from 1988 to 2005. Blood samples were used to survey peripheral blood for T. cruzi hemoparasites by quantitative buffy coat (QBC), indirect xenodiagnosis, blood culture and serology to detection of total IgM and anti-T. cruzi IgG antibodies by indirect immunofluorescence assay (IFA) and indirect hemagglutination assay (HA). All assays were performed pre-treatment (0 days) and repeated 35 (±7) and 68 (±6) days after the initiation of treatment with benznidazol and every 6 months while remained seropositive. The endpoint of collection was performed in 2005. Total medium period of follow-up per person was 5.6 years. Also, a blood sample was collected from 72 randomly chosen treated patients to perform polimerase chain reaction (PCR) method. Proportions of subjects with negative or positive serology according to the number of years after treatment were compared. In the endpoint of follow-up we found 47 patients (26.7%) serologically negative, therefore considered cured and 5 (2.7%) exhibited mild cardiac Chagas disease. Other 132 patients had persistent positive serologic tests. The PCR carried out in 72 individuals was positive in 9.8%. Added, there was evidence of therapeutic failure immediately following treatment, as demonstrated by xenodiagnosis and blood culture methods in 2.3% and 3.5% of cases, respectively. There was a strong evidence of antibody clearing in the fourth year after treatment and continuous decrease of antibody titers. Authors suggest that control programs should apply operational researches with new drug interventions four years after the acute phase for those treated patients with persistently positive serology.

Investigation of two outbreaks of suspected oral transmission of acute Chagas disease in the Amazon region, Para State, Brazil, in 2007

Acute Chagas disease (ACD) is caused by Trypanosoma cruzi. ACD outbreaks due to probable oral transmission occur regularly in small family gatherings that are exposed to contaminated foods. We studied two cohorts of residents on islands in the Breves and Bagre municipalities, in July and August 2007, to identify risk factors of transmission and to recommend preventative measures. Of the 25 cases identified in both cohorts, 13 (52%) were men, and the most frequent symptoms were fever (96%),asthenia (80%), myalgia (76%), abdominal pain (64%), retro-orbital pain, headaches and asthma (52%). We recommend detailed investigation of future outbreaks and other studies to better understand and control oral transmission of T. cruzi.

Fase aguda da doença de Chagas na Amazônia brasileira: estudo de 233 casos do Pará, Amapá e Maranhão observados entre 1988 e 2005

Foram estudados 233 casos de fase aguda da doença de Chagas, oriundos do Pará, Amapá e Maranhão, observados no período de 1988 a 2005, cento e sessenta deles retrospectivamente de 1988 a 2002 e setenta e três prospectivamente de 2003 a 2005. Entre os casos estudados 78,5% (183/233) faziam parte de surtos provavelmente por transmissão oral, acometendo em média 4 pessoas e 21,5% (50/233) eram casos isolados. Foram considerados casos agudos aqueles que apresentaram exames parasitológicos diretos (a fresco, gota espessa ou Quantitative Buffy Coat - QBC) e/ou IgM anti-Trypanosoma cruzi positivos. Foram feitos ainda xenodiagnósticos em 224 pacientes e hemoculturas em 213. Todos foram avaliados clinica e epidemiologicamente. As manifestações clínicas mais freqüentes foram febre (100%), cefaléia (92,3%), mialgia (84,1%), palidez (67%), dispnéia (58,4%), edema de membros inferiores (57,9%), edema de face (57,5%) dor abdominal (44,2%), miocardite (39,9%) e exantema (27%). O eletrocardiograma mostrou alterações de repolarização ventricular em 38,5% dos casos, baixa voltagem de QRS em 15,4% e desvio de SAQRS em 11,5%, extra-sístoles ventriculares em 5,8%, bradicardia em 5,8% e taquicardia em 5,8%, bloqueio de ramo direito em 4,8% e fibrilação atrial em 4,8%. A alteração mais freqüente vista no ecocardiograma foi o derrame pericárdico em 46,2% dos casos. Treze (5,6%) pacientes evoluíram para o óbito, 10 (76,9%) dos quais por comprometimento cardiovascular, dois por complicações de origem digestiva e um de causa mal definida.

Emerging acute Chagas disease in Amazonian Brazil: case reports with serious cardiac involvement

Four cases of serious cardiac attacks by autochthonous Trypanosoma cruzi infection from the Brazilian Amazon are reported; three of them occurred in micro-epidemic episodes. The manifestations included sudden fever, myalgia, dyspnea and signs of heart failure. Diagnosis was confirmed by specific exams, especially QBC (Quantitative Buffy Coat) and natural xenodiagnosis. Despite treatment with benznidazol, three patients died with serious myocarditis, renal failure and cardiac tamponade. The authors call attention to the emergence of this disease and reveal a previously unknown pathogenicity of T. cruzi strains in this area, added to a non-usual transmission form.

Chromosomal evolution trends of the genus Panstrongylus (Hemiptera, Reduviidae), vectors of Chagas disease

The genus Panstrongylus includes 14 species widely distributed from Mexico to Argentina, some of them with great epidemiological significance as vectors of Chagas disease. We study the karyotype and the male meiotic process of Panstrongylus chinai, P. geniculatus, P. herreri, P. lignarius, P. megistus, P. rufotuberculatus and P. tupynambai. All species present the same sex mechanism (X(1)X(2)Y in males and X(1)X(1)X(2)X(2) in females) and they also have 20 autosomes, with the exception of P. megistus that only presents 18 autosomes. The analysis of C-banding patterns and meiotic chromosome behaviour show a great level of variability allowing the identification of three clearly differentiated groups. In the first group, we only include P. megistus because of its unusual number of autosomes. The second group includes P. chinai, P. herreri, P. lignarius and P. rufotuberculatus. Their autosomes present terminal heterochromatic regions that appear scattered throughout the nucleus and associated with the sex chromosomes. Actually, P. herreri and P. lignarius can be considered cytogenetically identical. Our results are in agreement with morphological, ecological and molecular data indicating that they should be regarded as the same species. The third group only includes P. tupynambai that shows autosomes without C-positive regions. Panstrongylus geniculatus shares characters will all the three groups. Its karyotypic features are extremely polymorphic depending on their geographic origin. Some populations do not show any heterochromatic regions, while others exhibit few or several heterochromatic blocks. The chromosomal variability observed, together with its wide distribution and phenetic variability, suggest that P. geniculatus is a species complex comprising at least two distinct species. Considering the entire subfamily, the level of cytogenetic variation in Panstrongylus is lower than that observed in Triatoma but considerably more than that of Rhodnius, which is a very homogenous genus in terms of chromosome appearance and behaviour. This would endorse the closer relationship between Panstrongylus and Triatoma, and their divergence from Rhodnius, in accordance with current tribal classification.