The complement system present in circulating blood is an effective mechanism of host defense, responsible for the killing of pathogens and the production of potent anaphylatoxins. Inhibitors of the complement system have been described in the saliva of hematophagous arthropods that are involved in the protection of digestive tissues against complement system–mediated damage. In this study, we describe albicin, a novel inhibitor of the alternative pathway of complement from the salivary glands of the malaria vector, Anopheles albimanus. The inhibitor was purified from salivary gland homogenates by reverse-phase HPLC and identified by mass spectrometry as a small (13.4-kDa) protein related to the gSG7 protein of Anopheles gambiae and Anopheles stephensi. Recombinant albicin was produced in Escherichia coli and found to potently inhibit lysis of rabbit erythrocytes in assays of the alternative pathway while having no inhibitory effect on the classical or lectin pathways. Albicin also inhibited the deposition of complement components on agarose-coated plates, although it could not remove previously bound components. Antisera produced against recombinant albicin recognized both the native and recombinant inhibitors and also blocked their activities in in vitro assays. Using surface plasmon resonance and enzymatic assays, we found that albicin binds and stabilizes the C3-convertase complex (C3bBb) formed on a properdin surface and inhibits the convertase activity of a reconstituted C3bBb complex in solution. The data indicate that albicin specifically recognizes the activated form of the complex, allowing more efficient inhibition by an inhibitor whose quantity is limited.

Objective: The objective of this study was to develop an evidence map on the strategies for preventing and controlling Aedes aegypti infestation and related viral infections. Methods: The evidence map was created according to the methodology of the Latin American and Caribbean Center on Health Sciences Information (BIREME). Publication searches were performed in MEDLINE/PubMed and the Virtual Health Library, filtered for systematic reviews (SRs) only. The methodological quality of the SR was accessed using the AMSTAR2 tool, and Tableau software was used to construct the evidence map. Results: A total of 44 SRs on the prevention and control of A. aegypti infestation and related viral infections (dengue, chikungunya, Zika, and yellow fever viruses) were included in the map. The evidence map indicates 130 associations between 59 interventions and 18 outcomes. The reported interventions were categorized into 10 groups, including community/educational actions, use of repellents, immunization, individual protection, diagnostics, biological and chemical control of the vector, epidemiological surveillance, environmental actions, and combined interventions. The described outcomes were grouped as mosquito infestation, behavior change, prevention and control, immunological response, safety, and epidemiological surveillance. Conclusion: The elaborated map highlighted strong evidence supporting the effectiveness of vaccination, DEET repellents, community participation, chemical control of the vector, and combined housing interventions in protecting against the vector and transmitted viruses. Nonetheless, several evidence gaps remain in the knowledge of how to best prevent and control the vector and its related viral infections, underscoring the need for high-quality SRs and primary studies.

INTRODUCTION Triatomine bugs are hematophagous insects that are extremely important in public health because they are natural vectors of Trypanosoma cruzi, the causative agent of Chagas disease. In this study, we aimed to assess the occurrence of triatomine species and the natural T. cruzi infection in the Guaribas Valley territory, an endemic region for Chagas disease in northeastern Brazil. METHODS Insects were actively captured from July 2017 to October 2019 in the intra- and peridomiciles of 16 municipalities of the Guaribas Valley territory, in the southeast area of Piauí state. Triatomine species were identified following a taxonomic key, and natural infection was investigated through insects’ fresh feces exams. RESULTS A total of 430 triatomines were collected, including 211 nymphs and 219 adults. Of all collected specimens, 39 (9.1%) were from the intradomiciles and 391 (90.9%) from peridomiciles. Nine species, including two subspecies, could be identified: Triatoma brasiliensis brasiliensis, T. brasiliensis macromelasoma, T. pseudomaculata, T. sordida, T. juazeirensis, T. melanocephala, Panstrongylus lutzi, Rhodnius domesticus, R. nasutus, and R. robustus. T. brasiliensis were the most frequently collected bugs, representing 72% of all the identified insects. None of the examined invertebrates presented flagellate forms of T. cruzi. CONCLUSIONS: This is the first report of T. b. macromelasoma and T. juazeirensis in the Guaribas Valley territory. The persistence of triatomine species in the domiciles in an endemic area for Chagas disease emphasizes the relevance of entomological surveillance and vector control measures in the studied area.

The triatomine insect Panstrongylus megistus , one of the most important Chagas disease vectors in Brazil, presents salivary molecules pharmacologically active to counteract homeostatic responses from the host, including inhibitors of the human complement system, a major effector of immune responses. The aim of the present study was to investigate the effect of P. megistus salivary gland extract (SGE) on the complement system from different host species and characterize the inhibitory effect of SGE and intestinal contents on human complement. Glands and midguts from fourth instar nymphs were used. Hemolytic assays were performed with sheep erythrocytes as complement activators by using human, rats and chickens sera in the presence or absence of SGE. An ELISA assay was carried out detect deposition of the C3b component on IgG- or agarose-sensitized microplates, in the presence or absence of SGE or midgut contents. P. megistus SGE was able to significantly inhibit the complement of the three studied species (human, rat and chiken). Both, SGE and midgut contents inhibited C3b deposition in either the classical or the alternative pathways. As conclusions, SGE and midgut from P. megistus possess anti-complement activity. The inhibitors are effective against different host species and act on the initial steps of the complement system cascade. These inhibitors may have a role in blood feeding and Trypanosoma cruzi transmission by the vector.

Objective To investigate the epidemiological profile and spatial distribution of human visceral leishmaniasis cases in Crateús, Ceará, Brazil, from 2007 to 2023. Methods This was a retrospective, descriptive cross-sectional study based on epidemiologic data from the Notifiable Health Conditions Information System regarding human visceral leishmaniasis in Crateús between 2007 and 2023. The variables assessed were sex, age group at the time of diagnosis, race/skin color, education level, HIV coinfection, case outcome, neighborhood of residence, area of residence, and number of deaths per year of notification. Relative frequency, incidence, and lethality rates were calculated; maps were created to reflect the spatial distribution of cases within the municipality. Results Between 2007 and 2023, 112 cases of visceral leishmaniasis were reported in Crateús, predominantly among males (n=77), brown-skinned individuals (n=81), aged 20-39 years (n=27), with incomplete elementary education (n=31), and residing in urban areas of the municipality (n=88). The incidence rate decreased from 22.81 in 2007 to 16.02 in 2008, with a peak of 14.67 in 2018; by 2023, the incidence rate had dropped to 10.47. There were four cases of HIV coinfection and two deaths directly attributable to the disease. Conclusion Cases of visceral leishmaniasis in Crateús were concentrated in the urban area of the municipality. The epidemiologic profile was consistent with national trends, with the most affected individuals being of mixed race/skin color, male, aged 20-39 years, and with incomplete elementary education.