Efficacy of a spatial repellent for control of Aedes-borne virus transmission: A cluster-randomized trial in Iquitos, Peru.

Over half the world's population is at risk for viruses transmitted by Aedes mosquitoes, such as dengue and Zika. The primary vector, Aedes aegypti, thrives in urban environments. Despite decades of effort, cases and geographic range of Aedes-borne viruses (ABVs) continue to expand. Rigorously proven vector control interventions that measure protective efficacy against ABV diseases are limited to Wolbachia in a single trial in Indonesia and do not include any chemical intervention. Spatial repellents, a new option for efficient deployment, are designed to decrease human exposure to ABVs by releasing active ingredients into the air that disrupt mosquito-human contact. A parallel, cluster-randomized controlled trial was conducted in Iquitos, Peru, to quantify the impact of a transfluthrin-based spatial repellent on human ABV infection. From 2,907 households across 26 clusters (13 per arm), 1,578 participants were assessed for seroconversion (primary endpoint) by survival analysis. Incidence of acute disease was calculated among 16,683 participants (secondary endpoint). Adult mosquito collections were conducted to compare Ae. aegypti abundance, blood-fed rate, and parity status through mixed-effect difference-in-difference analyses. The spatial repellent significantly reduced ABV infection by 34.1% (one-sided 95% CI lower limit, 6.9%; one-sided P value = 0.0236, z = 1.98). Aedes aegypti abundance and blood-fed rates were significantly reduced by 28.6 (95% CI 24.1%, ∞); z = -9.11) and 12.4% (95% CI 4.2%, ∞); z = -2.43), respectively. Our trial provides conclusive statistical evidence from an appropriately powered, preplanned cluster-randomized controlled clinical trial of the impact of a chemical intervention, in this case a spatial repellent, to reduce the risk of ABV transmission compared to a placebo.

COVID-19 Bereavement in Ten Latin American Countries: Measurement Invariance of the Pandemic Grief Scale and Its Relation to Suicidal Ideation.

The present study aimed to evaluate the cross-cultural measurement invariance of the Pandemic Grief Scale (PGS) in ten Latin American countries. A total of 2,321 people who had lost a family member or other loved one due to COVID-19 participated, with a mean age of 34.22 years old (SD = 11.99). In addition to the PGS, a single item of suicidal ideation was applied. The unidimensional model of the PGS had adequate fit in most countries and good reliability estimates. There was evidence of measurement invariance by country and gender. Also, a one-point increase in the PGS was associated with an almost twofold increase in the odds of suicidal ideation. Scores greater than or equal to 4 on the PGS are proposed as a cut off to identify individuals with suicidal ideation. Strong evidence of the cross-cultural validity of the PGS is provided.

Cross-cultural validation of the new version of the Coronavirus Anxiety Scale in twelve Latin American countries.

The Coronavirus Anxiety Scale (CAS) was recently developed to assess dysfunctional anxiety related to COVID-19. Although different studies reported that the CAS is psychometrically sound, it is unclear whether it is invariant across countries. Therefore, the present study aimed to examine the measurement invariance of the CAS in twelve Latin American countries (Argentina, Bolivia, Chile, Colombia, Cuba, Ecuador, El Salvador, Guatemala, Mexico, Paraguay, Peru, and Uruguay). A total of 5196 people participated, with a mean age of 34.06 (SD = 26.54). Multigroup confirmatory factor analysis (CFA) was used to examine the measurement invariance of the CAS across countries and gender. Additionally, the graded response model (GRM) was used to provide a global representation of the representativeness of the scale with respect to the COVID-19 dysfunctional anxiety construct. The unidimensional structure of the five-item CAS was not confirmed in all countries. Therefore, it was suggested that a four-item model of the CAS (CAS-4) provides a better fit across the twelve countries and reliable scores. Multigroup CFA showed that the CAS-4 exhibits scalar invariance across all twelve countries and all genders. In addition, the CAS-4 items are more informative at average and high levels of COVID-19 dysfunctional anxiety than at lower levels. According to the results, the CAS-4 is an instrument with strong cross-cultural validity and is suitable for cross-cultural comparisons of COVID-19 dysfunctional anxiety symptoms in the general population of the twelve Latin American countries evaluated. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s12144-021-02563-0.

Rickettsia asembonensis Characterization by Multilocus Sequence Typing of Complete Genes, Peru.

While studying rickettsial infections in Peru, we detected Rickettsia asembonensis in fleas from domestic animals. We characterized 5 complete genomic regions (17kDa, gltA, ompA, ompB, and sca4) and conducted multilocus sequence typing and phylogenetic analyses. The molecular isolate from Peru is distinct from the original R. asembonensis strain from Kenya.

Establishment of a free-mating, long-standing and highly productive laboratory colony of Anopheles darlingi from the Peruvian Amazon.

BACKGROUND: Anopheles darlingi is the main malaria vector in the Amazon region and is among the most efficient malaria vectors worldwide. However, due to the lack of a well-established laboratory colony, key control-relevant aspects of the bionomics, behaviour, genetics, and vector-parasite relationships of An. darlingi remain unknown. Here, biological parameters that had been successful in initiating other Anopheles colonies were optimized and improved for An. darlingi, with the aim of establish a free-mating, stable, and highly productive laboratory colony. METHODS: Wild An. darlingi adult females were field collected from Zungarococha, Loreto Department, Peru (03°49'32.40″S, 73°21'00.08″W), and taken to the NAMRU-6 Insectary in Iquitos where F(1) offspring were produced and reared. Natural copulation was successfully induced in F1 adults under a thermoperiod of 30 ± 1 °C during the day and 25 ± 1 °C at night, and with a 30-min LED light stimulation period at dusk. Oviposition success was enhanced using egg-laying containers with a dark-coloured surface. Larval feeding regimes were standardized for optimal larval development. Optimized copulation induction methods were used to facilitate mating in An. darlingi until the F(10) generation. No copulation induction assistance was needed in subsequent generations. RESULTS: In 19 generations, the An. darlingi colony produced a total of 763,775 eggs; 441,124 larvae; 248,041 pupae; and 231,591 adults. A mean of 0.56 sexual encounters/female/cage (n = 36 cages) was recorded across the first ten generations (F(1)-F(10)). A mean insemination rate of 54.7 % (n = 5,907 females) ranging from 43.6 % (F(2)) to 66.6 % (F(10)) was recorded across nine generations (F(2)-F(10)). Free-mating was casually observed in the F(8) generation, and subsequently confirmed in the F(9) and F(10) generations; comparable insemination rates and egg laying between stimulated (51.6 %, 12.9 eggs/female), and non-stimulated (52.3 %, 11.2 eggs/female) females were recorded. The time from egg to adult development ranged from 10 to 20 days. Moreover, the colony was relocated to a new laboratory within Iquitos in the F(14) generation without any noted changes in its productivity. By March 2015, the An. darlingi colony has been successfully reared to the F(26) generation. CONCLUSIONS: This constitutes the first report of a free-mating, highly productive, and long-standing An. darlingi laboratory colony established through natural copulation induction, which will support critical malaria research. This rearing methodology may be a transferable, cost-effective alternative to labour-intensive forced mating practices widely used in maintaining other Anopheles colonies.

High Levels of Diversity in Anopheles Subgenus Kerteszia Revealed by Species Delimitation Analyses.

The Anopheles subgenus Kerteszia is a poorly understood group of mosquitoes that includes several species of medical importance. Although there are currently twelve recognized species in the subgenus, previous studies have shown that this is likely to be an underestimate of species diversity. Here, we undertake a baseline study of species delimitation using the barcode region of the mtDNA COI gene to explore species diversity among a geographically and taxonomically diverse range of Kerteszia specimens. Beginning with 10 of 12 morphologically identified Kerteszia species spanning eight countries, species delimitation analyses indicated a high degree of cryptic diversity. Overall, our analyses found support for at least 28 species clusters within the subgenus Kerteszia. The most diverse taxon was Anopheles neivai, a known malaria vector, with eight species clusters. Five other species taxa showed strong signatures of species complex structure, among them Anopheles bellator, which is also considered a malaria vector. There was some evidence for species structure within An. homunculus, although the results were equivocal across delimitation analyses. The current study, therefore, suggests that species diversity within the subgenus Kerteszia has been grossly underestimated. Further work will be required to build on this molecular characterization of species diversity and will rely on genomic level approaches and additional morphological data to test these species hypotheses.

Is the meaning of subjective well-being similar in Latin American countries? A cross-cultural measurement invariance study of the WHO-5 well-being index during the COVID-19 pandemic.

BACKGROUND: There is an urgent need to assess changes in well-being on a multinational scale during the COVID-19 pandemic, thus culturally valid scales must be available. METHODS: With this in mind, this study examined the invariance of the WHO well-being index (WHO-5) among a sample of 5183 people from 12 Latin Americans countries (Argentina, Bolivia, Chile, Colombia, Cuba, Ecuador, El Salvador, Guatemala, Mexico, Paraguay, Peru, and Uruguay). RESULTS: The results of the present study indicate that the WHO-5 is strictly invariant across samples from different Latin American countries. Furthermore, the results of the IRT analysis indicate that all items of the WHO-5 were highly discriminative and that the difficulty required to respond to each of the five items is ascending. Additionally, the results indicated the presence of moderate and small size differences in subjective well-being among most countries. CONCLUSION: The WHO-5 is useful for assessing subjective well-being in 12 Latin American countries during the COVID-19 pandemic, since the differences between scores can be attributed to differences in well-being and not in other characteristics of the scale.

Molecular Characterization by Multilocus Sequence Typing and Diversity Analysis of Rickettsia asembonensis in Peru.

Despite several reports worldwide documenting the presence of Rickettsia asembonensis in samples derived from ectoparasites, animals and more recently humans, genomic information of these specimens remains scarce, and when available, is usually limited to small genomic fragments of limited value. We generated complete sequences for two conserved (17-kDa antigen gene and gltA) and three variable (sca4, ompB and ompA) genes in five R. asembonensis DNA samples detected in cat and dog fleas in Peru. Complete gene sequences were used to conduct multi-locus sequence typing and phylogenetic analyses to assess diversity and infer relationships among strains and other reference sequences. The 17-kDa antigen gene was highly conserved across Rickettsia species. Of the variable genes ompB was the most variable, but this diversity was not captured through phylogenetics alone even when efforts were made to maximize potential diversity in terms of flea species, animal host and location. Through a combination of de novo and reference-based genome assembly we identified a 75 bp insertion in ompA that encodes a 25 aa repetitive motif found in other Rickettsia species, but not present in the original prototype strain from Kenya. R. asembonensis has only recently been shown to be a bona-fide human pathogen. As such, and compounded by a lack of available genomic information, it remains understudied. Our work directly addresses the lack of genomic information available worldwide for the study of these novel Rickettsia species and specifically contributes to our understanding of the diversity and molecular epidemiology of R. asembonensis in Peru.

Field Evaluation of Novel Spatial Repellent Controlled Release Devices (CRDs) against Mosquitoes in an Outdoor Setting in the Northern Peruvian Amazon.

U.S. military troops are exposed to mosquito-borne pathogens when deployed to endemic regions. Personal protective measures such as permethrin-treated uniforms and dermal repellents are the cornerstones of mosquito-borne disease prevention for the U.S. military. These measures have limitations and additional personal protection tools, such as spatial repellent devices to decrease the risk of vector-borne pathogen transmission, are required. Novel spatial repellent controlled-release devices formulated with metofluthrin were evaluated in an outdoor setting in the northern Amazon of Peru to evaluate performance under field conditions. The metofluthrin emitting devices lowered the number of mosquitoes captured in protected human landing collections (HLC) compared to blank devices, although there were effect differences between Anopheles spp. and species in other mosquito genera. A computational-experimental model was developed to correlate HLC and active ingredient (AI) concentrations as a function of time and space. Results show a strong correlation between the released AI and the decrease in HLC. This model represents the first effort to obtain a predictive analytical tool on device performance using HLC as the entomological endpoint.

Molecular Characterization of Bartonella Species Discovered in Ectoparasites Collected from Domestic Animals, Cuzco, Peru.

Rickettsiae and bartonellae are Gram-negative bacteria that can cause zoonotic and human diseases and are vectored by hematophagous arthropods. In the Americas, rickettsioses and bartonelloses have reemerged as significant public health threats. Bartonella species have been identified as causing zoonotic infections responsible for a variety of clinical syndromes in humans and animals. The aim of this study was to investigate the distribution, prevalence, and molecular heterogeneity of Rickettsia spp. and Bartonella spp. among ectoparasites collected from domestic animals in 14 farming communities in the Andes Mountains of Cuzco, Peru. A total of 222 domestic animals representing 8 different species (sheep, donkeys, goats, cattle, pigs, llamas, guinea pigs, and horses) were sampled. Nine species of ectoparasites (n = 1,697) collected from 122 animals were identified resulting in 1,657 chewing lice, 39 ticks, and 1 flea. DNA was individually extracted from a random sample of 600 (35.4%) considering variability of ectoparasite species, hosts, and sample location elevation. All 600 samples were negative for rickettsial DNA by a genus-specific molecular assay. A subset of 173 (28.8%) samples were selected based on variability of arthropods species, host, and location for Bartonella testing. Ninety-one (52.6%) of these samples including Melophagus ovinus (90/110) and Bovicola bovis (1/7) were positive for Bartonella by a genus-specific molecular assay. Five Bartonella genes of seven DNA samples from M. ovinus were analyzed by the multilocus sequence typing for characterization. We identified five identical Bartonella melophagi specimens and two specimens with Bartonella species related to B. melophagi from the seven M. ovinus. The Bartonella agents detected were widely distributed and frequent in multiple studied locations.

Cross-Cultural Validation of a New Version in Spanish of Four Items of the Preventive COVID-19 Infection Behaviors Scale (PCIBS) in Twelve Latin American Countries.

The invariance of the Preventive COVID-19 Infection Behaviors Scale (PCIBS) was evaluated in 12 Latin American countries (Argentina, Bolivia, Chile, Colombia, Cuba, Ecuador, El Salvador, Guatemala, Mexico, Paraguay, Peru, and Uruguay). A total of 5183 people from the aforementioned countries participated, selected using the snowball sampling method. Measurement invariance was assessed by multigroup confirmatory factor analysis (MG-CFA) and Multi-Group Factor Analysis Alignment (CFA-MIAL). In addition, item characteristics were assessed based on Item Response Theory. The results indicate that the original five-item version of the PCIBS is not adequate; whereas a four-item version of the PCIBS (PCIBS-4) showed a good fit in all countries. Thus, using the MG-CFA method, the PCIBS-4 achieved metric invariance, while the CFA-MIAL method indicated that the PCIBS-4 shows metric and scalar invariance. Likewise, the four items present increasing difficulties and high values in the discrimination parameters. The comparison of means of the PCIBS-4 reported irrelevant differences between countries; however, Mexico and Peru presented the highest frequency of preventive behaviors related to COVID-19. It is concluded that the PCIBS-4 is a unidimensional self-report measure which is reliable and invariant across the twelve participating Latin American countries. It is expected that the findings will be of interest to social and health scientists, as well as those professionals directly involved in public health decision making.

Influence of psychosocial factors on the development of sleep bruxism among children.

BACKGROUND: Bruxism is described as an orofacial parafunction that affects both children and adults. The maintenance of the childhood habit into adulthood may compromise health. As there are few studies on this issue, there is a need for further research on sleep bruxism among children. AIM: The aim of this study was to assess the prevalence of sleep bruxism in children and the influence of psychosocial factors. METHODS: A cross-sectional study was carried out on 652 randomly selected children aged 7-10 years at public and private schools in Belo Horizonte, Brazil. The instruments used were: questionnaire for parents, Child Stress Scale, and the scales on neuroticism and responsibility from the prevalidated Big Five Questionnaire for Children. Psychological tests were administered and evaluated by psychologists. Sleep bruxism among children was reported by parents. The Social Vulnerability Index from the city hall database was used to determine the social classification of the families. The chi-squared test, binary and multivariate logistic regressions were used, with the significance level set at 5%. RESULTS: A 35.3% prevalence of bruxism was found. No association was found between bruxism and stress, gender, age, or social vulnerability. The adjusted logistic model determined that children with high levels of neuroticism (OR = 1.9, CI 1.3-2.6) and responsibility (OR = 2.2, CI 1.0-5.0) are twice as likely to have the habit of sleep bruxism when compared to those who have low levels of these personality traits. CONCLUSIONS: A high degree of responsibility and neuroticism, which are individual personality traits, are determinant factors for the development of sleep bruxism among children.

Seroprevalence and Risk Factors for Rickettsia and Leptospira Infection in Four Ecologically Distinct Regions of Peru.

Rickettsia and Leptospira spp. are under-recognized causes of acute febrile disease worldwide. Rickettsia species are often placed into the spotted fever group rickettsiae (SFGR) and typhus group rickettsiae (TGR). We explored the antibody prevalence among humans for these two groups of rickettsiae in four regions of Peru (Lima, Cusco, Puerto Maldonado, and Tumbes) and for Leptospira spp. in Puerto Maldonado and Tumbes. We also assessed risk factors for seropositivity and collected serum samples and ectoparasites from peri-domestic animals from households in sites with high human seroprevalence. In total, we tested 2,165 human sera for antibodies (IgG) against SFGR and TGR by ELISA and for antibodies against Leptospira by a microscopic agglutination test. Overall, human antibody prevalence across the four sites was 10.6% for SFGR (ranging from 6.2% to 14.0%, highest in Tumbes) and 3.3% for TGR (ranging from 2.6% to 6.4%, highest in Puerto Maldonado). Factors associated with seroreactivity against SFGR were male gender, older age, contact with backyard birds, and working in agriculture or with livestock. However, exposure to any kind of animal within the household decreased the odds ratio by half. Age was the only variable associated with higher TGR seroprevalence. The prevalence of Leptospira was 11.3% in Puerto Maldonado and 5.8% in Tumbes, with a borderline association with keeping animals in the household. We tested animal sera for Leptospira and conducted polymerase chain reaction (PCR) to detect Rickettsia species among ectoparasites collected from domestic animals in 63 households of seropositive participants and controls. We did not find any association between animal infection and human serostatus.

The Dissociation between Adult Intelligence and Personality with Respect to Maltreatment Episodes and Externalizing Behaviors Occurring in Childhood.

Here we analyze the simultaneous relationships among five variables. Two refer to childhood (episodes of various forms of maltreatment and externalizing behaviors), whereas three refer to early adulthood (intelligence, personality, and socialization difficulties). The 120 individuals considered for the present report were invited from the 650 schoolchildren participating in the Longitudinal Study of Intelligence and Personality (Minas Gerais, Brazil). The complete sample was recruited in 2002 (T1; mean age = 10.0; standard deviation (SD) = 2.2) and 120 were tested again in 2014-17 (T2; mean age = 23.5; SD = 2.2). Externalizing behaviors were registered at T1, whereas the remaining variables were obtained at T2. These were the main results: (1) externalizing behaviors predict future social effectiveness (as estimated by the general factor of personality derived from the NEO Personality Inventory-Revised (NEO-PI-R) and socialization difficulties computed from the socialization scale (SOC)) and future intelligence performance (as assessed by a set of fluid and crystallized tests); (2) episodes of self-reported childhood maltreatment predict social effectiveness, but not intelligence; (3) maltreatment and externalizing behaviors are unrelated; and (4) social effectiveness (personality) and intelligence are unrelated. Therefore, the findings support the dissociation between adult intelligence and personality with respect to maltreatment episodes and externalizing behaviors occurring in childhood. Implications of these findings for social policies aimed at preventing adult socially ineffective personalities are underscored.

How stable is the intelligence over time?: evidence from Brazilian data / Quão estável é a inteligência?: evidência a partir de dados brasileiros / ¿Cómo de estable es la inteligencia?: evidencias a partir de datos brasileños

There is strong scientific evidence that intelligence remains stable from childhood to adulthood; however, no study has examined the generalizability of these findings for native Brazilian samples. Here we present a study carried out in 2002 and from 2014-2017 (average timespan of 15 years) in order to verify the stability of psychometric intelligence. A sample of 120 participants (mean age Time 1 = 10.0 yrs, mean age Time 2 = 23.6 yrs) was assessed using the Raven's Progressive Matrices and verbal subtests from the WISC-III and WAIS-III. The results indicated a moderate coefficient (around .50) for intelligence differential stability independent of the measurement administered. Regarding absolute stability, real cognitive gains were observed from Time 1 to Time 2, despite controlling the effect of the regression toward the mean. Finally, sex (female) and intelligence were statistically significant predictors of rapid educational progression. (AU)

Existe sólida evidência científica que a inteligência permanece estável desde a infância até a idade adulta, embora não existam estudos que verifique a generalidade desse pressuposto para amostra de nativos brasileiros. Aqui um estudo desenvolvido em 2002 e 2014/2017 (intervalo médio de 15 anos) que verifica a estabilidade da inteligência psicométrica é apresentado. Uma amostra de 120 participantes (Tempo 1 = 10,0 anos, Tempo 2 = 23,6 anos) foi avaliada com o uso das Matrizes Progressivas de Raven e as escalas verbais do WISC-III e do WAIS-III. Os resultados indicaram um coeficiente de estabilidade diferencial da inteligência moderado (aproximadamente 0,50), independentemente do tipo de medida administrada. Com relação à estabilidade absoluta, observaram-se ganhos cognitivos do Tempo 1 para o Tempo 2, apesar do controle do efeito da regressão à média. Finalmente, o sexo (feminino) e a inteligência foram os preditores estatisticamente significativos de uma rápida progressão educacional. (AU)

Existen fuertes evidencias científicas de que la inteligencia permanece estable desde la niñez hasta la edad adulta; sin embargo, no hay estudios que verifiquen la generalización de este supuesto para muestra de brasileños nativos. Aquí presentamos un estudio realizado en 2002 y de 2014 a 2017 (intervalo de tiempo promedio de 15 años) que comprueba la estabilidad de la inteligencia psicométrica. Se evaluó el desempeño de 120 participantes (Tiempo 1 = 10,0 años y Tiempo 2 = 23,6 años) con las Matrices Progresivas de Raven y escalas verbales del WISC-III y del WAIS-III. Los resultados indicaron un coeficiente de la estabilidad diferencial intelectual moderada (aproximadamente .50), independiente del tipo de medida administrada. En cuanto a la estabilidad absoluta, se observaron ganancias cognitivas del Tiempo 1 al Tiempo 2, a pesar de controlar el efecto de la regresión hacia la media. Por último, el sexo (femenino) y la inteligencia fueron predictores estadísticamente significativos de una rápida progresión educativa. (AU)

Effects of Cognitive Training on Cognitive Performance of Healthy Older Adults.

The purpose of this study was to determine the immediate effects of cognitive training on healthy older adults and verify the transfer effects of targeted and non-targeted abilities. The design consisted of a semi-randomized clinical controlled trial. The final sample was composed of 80 volunteers recruited from a Brazilian community (mean age = 69.69; SD = 7.44), which were separated into an intervention group (N = 47; mean age = 69.66, SD = 7.51) and a control group (N = 33; mean age = 69.73, SD = 7.45). Intervention was characterized by adaptive cognitive training with 12 individual training sessions of 60 to 90 minutes (once a week). Eight instruments were used to assess effects of cognitive training. Five were used to assess trained abilities (near effects), including: Memorization Tests (List and History), Picture Completion, Digit Span, Digit Symbol-Coding, and Symbol Search (the last four from WAIS-III). Two instruments assessed untrained abilities (far effects): Arithmetic and Matrix Reasoning (WAIS-III). The non-parametric repeated measures ANOVA test revealed a significant interaction between group by time interaction for Picture Completion [F(74) = 14.88, p = .0002, d = 0.90, CLES = 73.69%], Digit Symbol-Coding [F(74) = 5.66, p = .019, d = 0.55, CLES = 65.21%] and Digit Span [F(74) = 5.38, p = .02, d = 0.54, CLES = 64.85%], suggesting an interventional impact on these performance tasks. The results supported near transfer effects, but did not demonstrate a far transfer effects.

Identification of Blood Meals from Potential Arbovirus Mosquito Vectors in the Peruvian Amazon Basin.

The transmission dynamics of many arboviruses in the Amazon Basin region have not been fully elucidated, including the vectors and natural reservoir hosts. Identification of blood meal sources in field-caught mosquitoes could yield information for identifying potential arbovirus vertebrate hosts. We identified blood meal sources in 131 mosquitoes collected from areas endemic for arboviruses in the Peruvian Department of Loreto by sequencing polymerase chain reaction amplicons of the cytochrome b gene. Psorophora (Janthinosoma) albigenu, Psorophora (Grabhamia) cingulata, Mansonia humeralis, Anopheles oswaldoi s.l., and Anopheles benarrochi s.l. had mainly anthropophilic feeding preferences; Aedes (Ochlerotatus) serratus, and Aedes (Ochlerotatus) fulvus had feeding preferences for peridomestic animals; and Culex (Melanoconion) spp. fed on a variety of vertebrates, mainly rodents (spiny rats), birds, and amphibians. On the basis of these feeding preferences, many mosquitoes could be considered as potential enzootic and bridge arbovirus vectors in the Amazon Basin of Peru.

Rickettsial Disease in the Peruvian Amazon Basin.

Using a large, passive, clinic-based surveillance program in Iquitos, Peru, we characterized the prevalence of rickettsial infections among undifferentiated febrile cases and obtained evidence of pathogen transmission in potential domestic reservoir contacts and their ectoparasites. Blood specimens from humans and animals were assayed for spotted fever group rickettsiae (SFGR) and typhus group rickettsiae (TGR) by ELISA and/or PCR; ectoparasites were screened by PCR. Logistic regression was used to determine associations between patient history, demographic characteristics of participants and symptoms, clinical findings and outcome of rickettsial infection. Of the 2,054 enrolled participants, almost 2% showed evidence of seroconversion or a 4-fold rise in antibody titers specific for rickettsiae between acute and convalescent blood samples. Of 190 fleas (Ctenocephalides felis) and 60 ticks (Rhipicephalus sanguineus) tested, 185 (97.4%) and 3 (5%), respectively, were positive for Rickettsia spp. Candidatus Rickettsia asemboensis was identified in 100% and 33% of the fleas and ticks tested, respectively. Collectively, our serologic data indicates that human pathogenic SFGR are present in the Peruvian Amazon and pose a significant risk of infection to individuals exposed to wild, domestic and peri-domestic animals and their ectoparasites.

Natural Plasmodium infections in Anopheles darlingi and Anopheles benarrochi (Diptera: Culicidae) from eastern Peru.

Malaria, both Plasmodium falciparum (Welch) and Plasmodium vivax (Grassi & Feletti), has reemerged as a significant public health disease issue in Peru, especially in forested areas in the eastern part of the country. The spread of Anopheles darlingi Root, the principal South American malaria vector, into new areas of Peru is thought to be a factor in this resurgence. However, epidemiological evidence suggests that in malaria endemic areas of eastern Peru where An. darlingi does not occur, other species are involved in malaria transmission. The objective of this study was to analyze Anopheles species collected from 11 provinces within four departments in eastern Peru during 2001 and 2002 for infections with P. falciparum and P. vivax. More than 84,000 Anopheles mosquitoes representing 13 species were tested by enzyme-linked immunosorbent assay for the presence of Plasmodium circumsporozoite (CS) proteins. Of these, only An. darlingi and Anopheles benarrochi Gabaldón, Cova García & López were found positive. In total, 14 (0.98%) of 1,432 pools of An. darlingi were positive for Plasmodium species; specifically 10 (0.70%) pools were positive for P. falciparum, two (0.14%) were positive for P. vivax VK210, and two (0.14%) were positive for P. vivax VK247 proteins. Nine (0.14%) of 6,323 pools of An. benarrochi were positive for Plasmodium; five (0.08%) of 6,323 pools were positive for P. falciparum, two (0.03%) were positive for P. vivax VK247, one (0.02%) was positive for mixed P. vivax VK210/VK247 infections, and one (0.02%) was positive for mixed P. falciparum and P. vivax VK210 CS-proteins. Although infection rates in An. benarrochi were significantly lower (0.14%) than rates found for An. darlingi (0.98%), our data suggest that An. benarrochi may play a role in transmitting and maintaining Plasmodium species in various malaria endemic areas of eastern Peru.

Geographical distribution of Anopheles darlingi in the Amazon Basin region of Peru.

Malaria has reemerged as a significant public health disease threat in Peru, especially within the Amazon Basin region. This resurgence of human cases caused by infection with Plasmodium falciparum and Plasmodium vivax is thought to be associated with the spread of Anopheles darlingi, the principal South American malaria vector, into new areas of the Amazon Basin. However, comprehensive studies of the distribution for this species have not been conducted in Peru for several years, nor are historical accounts accurate enough to determine if An. darlingi was actually present and not collected or misidentified. Therefore, the objective of this study is to define the distribution of An. darlingi as well as obtain data on distribution and abundance of other Anopheles species in this region. Mosquitoes were collected during 2001 in the Departments of Loreto and Ucayali, the two largest Amazonian Departments of Peru. A total of 60,585 specimens representing 12 species of the subgenera Nyssorhynchus and Anopheles were collected at 82 (88.2%) of 93 collecting sites. The majority of mosquitoes obtained were identified as An. benarrochi, comprising 70.7% of mosquitoes collected, followed by An. darlingi (24.0%), Anopheles mattogrosensis (2.4%), and Anopheles triannulatus (1.5%). Anopheles darlingi was collected from 48.8% of sites, indicating that this species is established throughout central Loreto, including further west in the Amazon Basin than previously reported. These data suggest that this species is now found in areas of the Amazon Basin region where it has not been previously reported.