Hidden sylvatic foci of the main vector of Chagas disease Triatoma infestans : threats to the vector elimination campaign?

The research investigates relatedness between sylvatic and domestic or peri domestic (D/PD) populations of T. infestans (transmitters of Chagas disease) and the threat that they may represent to vector control and elimination attempts in the Argentinean Chaco. The report establishes that the domestication process of T. infestans does not prevent the species from surviving at low density in a wide diversity of sylvatic or semi-sylvatic habitats, even after community-wide insecticide spraying. Results suggest that in areas with recurrent re-infestation, vector control programs should consider the potential occurrence of external sources (semi-sylvatic or sylvatic) around the target community

Lineage-specific rapid diagnostic tests can resolve Trypanosoma cruzi TcII/V/VI ecological and epidemiological associations in the Argentine Chaco.

BACKGROUND: Trypanosoma cruzi, the protozoan agent of Chagas disease, is comprised of at least 6 genetic lineages (TcI-TcVI). Their geographical distribution, clinical associations and reservoir hosts are not fully elucidated, as genotyping is hampered due to the difficulty in isolating representative populations of organisms. Lineage-specific serological techniques may address these issues. METHODS: Trypanosoma cruzi lineage-specific serological assays were performed on human, canine, feline and armadillo sera from the Gran Chaco in northern Argentina, a region of ongoing transmission. Synthetic peptides representing lineage-specific epitopes of the trypomastigote small surface antigen (TSSA) were used in ELISA, and the TcII/V/VI shared epitope peptide (TSSApep-II/V/VI) was used in the Chagas Sero K-SeT rapid diagnostic test (RDT). RESULTS: Chagas Sero K-SeT RDT, using Protein G to detect human and canine IgG, was at least as sensitive as TSSApep-II/V/VI ELISA using specific secondary antibodies. For sera from humans TSSApep-II/V/VI seroprevalence by Chagas Sero K-SeT was 273/393 (69.5%), for dogs 48/73 (65.8%) and for armadillos 1/7 (14.3%); by ELISA for cats 5/19 (26.3%). The seroprevalence for humans was similar to that for Bolivian patients, amongst whom we previously observed an association of TSSApep-II/V/VI seropositivity with severity of cardiomyopathy. In humans, prevalence of TSSApep-II/V/VI recognition was associated with locality, and with increasing and decreasing age within the Qom and Creole populations, respectively. For dogs TSSApep-II/V/VI recognition was associated with being born before community-wide insecticide spraying (P = 0.05) and with Qom household (P < 0.001). CONCLUSIONS: We show here that Chagas Sero K-SeT RDT can replace ELISA for TSSApep-II/V/VI serology of humans and dogs; for humans there were statistically significant associations between a positive Chagas Sero K-SeT RDT and being resident in Area IV, and for dogs association with Qom household or with being born before the mass spraying campaign; we also show that with cats the TcII/V/VI epitope can be detected by ELISA. We assessed the lineage distribution in an unprecedented 83% of the human T. cruzi-seropositive population. These results form the basis for more detailed studies, enabling rapid in-the-field surveillance of the distribution and clustering of these lineages among humans and mammalian reservoirs of T. cruzi infection

Similar Neural Activity during Fear and Disgust in the Rat Basolateral Amygdala

Much research has focused on how the amygdala processes individual affects, yet little is known about how multiple types of positive and negative affects are encoded relative to one another at the single-cell level. In particular, it is unclear whether different negative affects, such as fear and disgust, are encoded more similarly than negative and positive affects, such as fear and pleasure. Here we test the hypothesis that the basolateral nucleus of the amygdala (BLA), a region known to be important for learned fear and other affects, encodes affective valence by comparing neuronal activity in the BLA during a conditioned fear stimulus (fear CS) with activity during intraoral delivery of an aversive fluid that induces a disgust response and a rewarding fluid that induces a hedonic response. Consistent with the hypothesis, neuronal activity during the fear CS and aversive fluid infusion, but not during the fear CS and rewarding fluid infusion, was more similar than expected by chance. We also found that the greater similarity in activity during the fear- and disgust-eliciting stimuli was specific to a subpopulation of cells and a limited window of time. Our results suggest that a subpopulation of BLA neurons encodes affective valence during learned fear, and furthermore, within this subpopulation, different negative affects are encoded more similarly than negative and positive affects in a time-specific manner

Hidden Sylvatic Foci of the Main Vector of Chagas Disease Triatoma infestans: Threats to the Vector Elimination Campaign?

Triatoma infestans, a highly domesticated species and historically the main vector of Trypanosoma cruzi, is the target of an insecticide-based elimination program in the southern cone countries of South America since 1991. Only limited success has been achieved in the Gran Chaco region due to repeated reinfestations. We conducted full-coverage spraying of pyrethroid insecticides of all houses in a well-defined rural area in northwestern Argentina, followed by intense monitoring of house reinfestation and searches for triatomine bugs in sylvatic habitats during the next two years, to establish the putative sources of new bug colonies. We found low-density sylvatic foci of T. infestans in trees located within the species' flight range from the nearest infested house detected before control interventions. Using multiple methods (fine-resolution satellite imagery, geographic information systems, spatial statistics, genetic markers and wing geometric morphometry), we corroborated the species identity of the sylvatic bugs as T. infestans and found they were indistinguishable from or closely related to local domestic or peridomestic bug populations. Two sylvatic foci were spatially associated to the nearest peridomestic bug populations found before interventions. Sylvatic habitats harbor hidden foci of T. infestans that may represent a threat to vector suppression attempts

Direct molecular identification of Trypanosoma cruzi Discrete Typing Units in domestic and peridomestic Triatoma infestans and Triatoma sordida from the Argentine Chaco

We assessed the distribution of Trypanosoma cruzi Discrete Typing Units (DTUs) in domestic and peridomestic Triatoma infestans and Triatoma sordida specimens collected in a well-defined rural area in Pampa del Indio, northeastern Argentina. Microscopically-positive bugs were randomly selected with a multi-level sampling design, and DTUs were identified using direct PCR strategies. TcVI predominated in 61% of 69 T. infestans and in 56% of 9 T. sordida. TcV was the secondary DTU in T. infestans (16%) and was found in 1 T. sordida specimen (11%). Three T. sordida (33%) were found infected with TcI, a DTU also identified in local Didelphis albiventris opossums. Mixed DTU infections occurred rarely (5%) and were detected both directly from the bugs' rectal ampoule and parasite cultures. The identified DTUs and bug collection sites of T. infestans were significantly associated. Bugs infected with TcV were almost exclusively captured in domiciles whereas those with TcVI were found similarly in domiciles and peridomiciles. All mixed infections occurred in domiciles. TcV-infected bugs fed more often on humans than on dogs, whereas TcVI-infected bugs showed the reverse pattern. T. sordida is a probable sylvatic vector of TcI linked to D. albiventris, and could represent a secondary vector of TcVI and TcV in the domestic/peridomestic cycle.Fil: Maffey, L.. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ecología, Genética y Evolución; ArgentinaFil: Cardinal, Marta Victoria. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ecología, Genética y Evolución; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Ordóñez Krasnowski, P.C.. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ecología, Genética y Evolución; ArgentinaFil: Lanati, L. A,. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ecología, Genética y Evolución; ArgentinaFil: Lauricella, M. A.. Dirección Nacional de Instituto de Investigación. Administración Nacional de Laboratorio e Instituto de Salud “Dr. C. G. Malbrán”. Instituto Nacional de Parasitología "Dr. Mario Fatala Chaben”; ArgentinaFil: Schijman, Alejandro Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Investigaciones en Ingeniería Genética y Biología Molecular "Dr. Héctor N. Torres"; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Gurtler, Ricardo Esteban. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ecología, Genética y Evolución; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Domestic dogs and cats as sources of Trypanosoma cruzi infection in rural northwestern Argentina

The reservoir capacity of domestic cats and dogs for Trypanosoma cruzi infection and the host-feeding patterns of domestic Triatoma infestans were assessed longitudinally in 2 infested rural villages in north-western Argentina. A total of 86 dogs and 38 cats was repeatedly examined for T. cruzi infection by serology and/or xenodiagnosis. The composite prevalence of infection in dogs (60%), but not in cats, increased significantly with age and with the domiciliary density of infected T. infestans. Dogs and cats had similarly high forces of infection, prevalence of infectious hosts (41-42%), and infectiousness to bugs at a wide range of infected bug densities. The infectiousness to bugs of seropositive dogs declined significantly with increasing dog age and was highly aggregated. Individual dog infectiousness to bugs was significantly autocorrelated over time. Domestic T. infestans fed on dogs showed higher infection prevalence (49%) than those fed on cats (39%), humans (38%) or chickens (29%) among 1085 bugs examined. The basic reproduction number of T. cruzi in dogs was at least 8.2. Both cats and dogs are epidemiologically important sources of infection for bugs and householders, dogs nearly 3 times more than cats

Eating habits and lifestyle changes during the COVID-19 lockdown: A comparative study (before and during isolation) on the 9 de Julio city (Buenos Aires, Argentina) population

Following the COVID-19 proliferation beyond China&rsquo;s borders at the beginning of 2020, containment measures have been taken by different countries around the globe. Citizens were forced to stay at home. Specifically, on March 19th, the Argentine Government decided to implement the &ldquo;Social, preventive and mandatory isolation&rdquo;, strategy that unfortunately impacts on the lifestyle, the practise of physical activity and on the nutritional aspect of the population. The aim of this study was analize eating habits and lifestyle changes during the COVID-19 lockdown on the 9 de Julio city, Bs. As., Argentina. The survey was conducted using Google Form. The questionnaire was divided into different sections: sociodemographic data, eating habits, physical activity and concepts and emotions associated with isolation. The research reached 287 responses with a medium socioeconomic level. During isolation, the frequency of purchases decreased. It was observed an increase in the consumption of pasta, bread and cakes. Concerning the physical activity, approximately 70% declared to train before the COVID-19 lockdown, decreased by 13% during the lockdown. Other activities conducted during the COVID-19 lockdown; the most mentioned were cleaning the house, cooking, watching television, series and movies. A percentage greater than 50% of the surveyed population associated the situation of lockdown with positive emotions (share with my family, stay at home); while only 24% associate it with negative emotions (anxiety, anguish, fear). It is expected that most habits will return to normal, however, it would be interesting to know which of those developed, adopted and implemented during lockdown will remain in the new normality

New Sylvatic Hosts of Trypanosoma cruzi and their reservoir competence in the humid Chaco of Argentina : a longitudinal study

A four-year longitudinal study of the structure of sylvatic transmission cycles of Trypanosoma cruzi, reservoir host competence and parasite discrete typing units was conducted in a disturbed rural area of the humid Chaco in Argentina. Among 190 mammals examined by xenodiagnosis and polymerase chain reaction amplification, the composite prevalence of infection was substantially higher in Dasypus novemcinctus armadillos (57.7%) and Didelphis albiventris opossums (38.1%) than in Euphractus sexcinctus (20.0%), Tolypeutes matacus (12.5%), and Chaetophractus vellerosus (6.3%) armadillos. Trypanosoma cruzi was detected for the first time in Thylamys pusilla small opossums and in two unidentified small rodents. Infection was spatially aggregated only in armadillos. All Didelphis were infected with T. cruzi I and all armadillo species were infected with T. cruzi III, implying two distinct sylvatic cycles with no inputs from the domestic cycle. Dasypus armadillos and Didelphis opossums were much more infectious to vectors than other armadillos, small opossums, or rodents

Distribution of domestic infestation prevalence and abundance of <i>T. infestans</i> according to housing, host and other characteristics, Pampa del Indio, Chaco, October 2008.

<p>^a domestic infestation was determined by the finding of at least one live bug by any of the bug collection methods used (i.e., timed-manual searches, during insecticide spraying operations, and householders’ bug collections).</p><p>^b bug abundance was calculated as the number of live bugs collected per 15 min-person among houses positive by timed-manual searches.</p><p>^c nesting indoors.</p><p>†includes all inhabited houses (n = 386).</p><p>OR: Crude odds ratio. RA: Relative abundance. CI: 95% confidence interval. Households with missing data were excluded for each variable. Age of house and domestic area were recorded in 2012.</p><p>*: CI not including 1.0.</p><p>Distribution of domestic infestation prevalence and abundance of <i>T. infestans</i> according to housing, host and other characteristics, Pampa del Indio, Chaco, October 2008.</p

Spatial distribution of house infestation by <i>T</i>. <i>infestans</i>.

<p>Pampa del Indio, Chaco, October 2008. A. Distribution of domestic and peridomestic infestation as determined by any bug collection method. B. Distribution of domestic abundance according to timed-manual collections.</p