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Leishmania are intracellular protozoan parasites that cause the vectorborne disease leishmaniasis, which occurs in [approximately equal to] 88 countries (1). Human infection can result in 2 main forms of disease, [...]

The calls of the Blue-fronted Amazon (Amazona aestiva) are described and their possible function within the social organization of the species during breeding and non-breeding seasons are discussed. We identified 9 vocalizations; six ('wak-wak', 'wa-wawawa', transitions, 'gu-gugu', guturals, 'ka-kaka') were nonspecific and were given in several circumstances: alarm, contact, feeding, and flying. The remaining had specific contexts: 'waahh' (agonistic), 'grr-uip' (contact in flight), and songs (reproduction-territorial). Vocalization rates increased in alarm contexts and during the non-breeding season, probably as a result of increasing interactions between individuals. The frequency containing the greatest amount of energy was a useful variable to characterize Blue-fronted Amazon calls, particularly at the species level. The most commonly used vocalization, 'wak-wak', has structural features that promote directionality and short-range transmission, enhancing its usefulness for the aggregation of individuals. It is suggested that songs were derived from a process of repetition and increasing variability from gutural calls. The highly contextual variability of these calls may be due to an incompletely specialized repertoire or a vocal system based upon combinations of calls for conveying messages., The Blue-fronted Amazon (Amazona aestiva) is a parrot whose distribution extends over northeastern Brazil, Bolivia, Paraguay, and northern Argentina (Forshaw 1977, Darrieu 1983). Populations have declined in recent years, especially [...]

Abstract Background There is a low incidence of malaria in Iquitos, Peru, suburbs detected by passive case-detection. This low incidence might be attributable to infections clustered in some households/regions and/or undetected asymptomatic infections. Methods Passive case-detection (PCD) during the malaria season (February-July) and an active case-detection (ACD) community-wide survey (March) surveyed 1,907 persons. Each month, April-July, 100-metre at-risk zones were defined by location of Plasmodium falciparum infections in the previous month. Longitudinal ACD and PCD (ACP+PCD) occurred within at-risk zones, where 137 houses (573 persons) were randomly selected as sentinels, each with one month of weekly active sampling. Entomological captures were conducted in the sentinel houses. Results The PCD incidence was 0.03 P. falciparum and 0.22 Plasmodium vivax infections/person/malaria-season. However, the ACD+PCD prevalence was 0.13 and 0.39, respectively. One explanation for this 4.33 and 1.77-fold increase, respectively, was infection clustering within at-risk zones and contiguous households. Clustering makes PCD, generalized to the entire population, artificially low. Another attributable-factor was that only 41% and 24% of the P. falciparum and P. vivax infections were associated with fever and 80% of the asymptomatic infections had low-density or absent parasitaemias the following week. After accounting for asymptomatic infections, a 2.6-fold increase in ACD+PCD versus PCD was attributable to clustered transmission in at-risk zones. Conclusion Even in low transmission, there are frequent highly-clustered asymptomatic infections, making PCD an inadequate measure of incidence. These findings support a strategy of concentrating ACD and insecticide campaigns in houses adjacent to houses were malaria was detected one month prior.