Complete genomic sequences of Venezuelan equine encephalitis virus subtype IIID isolates from mosquitoes.

Venezuelan equine encephalitis virus (VEEV) is an important pathogen of medical and veterinary importance in the Americas. In this report, we present the complete genome sequences of five VEEV isolates obtained from pools of Culex (Melanoconion) gnomatos (4) or Culex (Melanoconion) pedroi (1) from Iquitos, Peru. Genetic and phylogenetic analyses showed that all five isolates grouped within the VEEV complex sister to VEEV IIIC and are members of subtype IIID. This is the first report of full-length genomic sequences of VEEV IIID.

Determinants of Anopheles seasonal distribution patterns across a forest to periurban gradient near Iquitos, Peru.

As part of a field ecology study of arbovirus and malaria activity in the Amazon Basin, Loreto Department, Peru, we collected mosquitoes landing on humans at a forest site and inside and outside of residences and military barracks at periurban, rural, and village sites. We collected 11 Anopheles spp. from these four sites. An. darlingi, the principal malaria vector in the region, accounted for 98.7% of all Anopheles spp. collected at Puerto Almendra. Peaks in landing activity occurred during the December and April collection periods. However, the percent of sporozoite-positive Anopheles spp. was highest 1-2 months later, when landing activity decreased to approximately 10% of the peak activity periods. At all sites, peak landing activity occurred about 2 hours after sunset. These data provide a better understanding of the taxonomy, population density, and seasonal and habitat distribution of potential malaria vectors within the Amazon Basin region.

Seasonal distribution, biology, and human attraction patterns of mosquitoes (Diptera: Culicidae) in a rural village and adjacent forested site near Iquitos, Peru.

This study was conducted as part of a field-ecology study of arboviral and malarial activity in the Amazon Basin, Loreto Department, Peru, to determine the relative abundance, species diversity, and seasonal and vertical distributions of potential mosquito vectors. Mosquitoes were captured either by volunteers using mouth aspirators while mosquitoes attempted to land on the collectors or in dry ice-baited ABC light traps. Anopheles darlingi, the principal malaria vector in the region, was the most commonly captured anopheline mosquito in Puerto Almendra village (99%) while landing on humans, with a mean of 37.1 mosquitoes captured per 24-h period, representing nearly one half of all mosquitoes collected. An. darlingi human landing activity began shortly after sunset, peaked at 2000-2100 hours, and declined gradually until sunrise. This species readily entered houses, because 51% of the An. darlingi captured by paired collectors, stationed inside and outside houses, were captured indoors. Human landing collections provided a more accurate estimate of human attraction of An. darlingi, capturing 30 times as many as co-located dry ice-baited ABC light traps. In contrast, eight times as many Culex (Melanoconion) species, including known arbovirus vectors, were captured in light traps as by co-located human collectors. Despite being located within 300 m of the village collection site, only a few Anopheles species were captured at the forest collection site, including only 0.1 An darlingi/ 24 h, thus indicating that An. darlingi activity was directly associated with the rural village. These data provide a better understanding of the taxonomy, population density, and seasonal distribution of potential mosquito vectors of disease within the Amazon Basin region and allow for the development of appropriate vector and disease prevention strategies that target vector populations.

Endemic eastern equine encephalitis in the Amazon region of Peru.

Eastern equine encephalitis virus (EEEV) causes severe neurologic disease in North America, but only two fatal human cases have been documented in South America. To test the hypothesis that alphavirus heterologous antibodies cross-protect, animals were vaccinated against other alphaviruses and challenged up to 3 months later with EEEV. Short-lived cross-protection was detected, even in the absence of cross-neutralizing antibodies. To assess exposure to EEEV in Peru, sera from acutely ill and healthy persons were tested for EEEV and other alphavirus antibodies, as well as for virus isolation. No EEEV was isolated from patients living in an EEEV-enzootic area, and only 2% of individuals with febrile illness had EEEV-reactive IgM. Only 3% of healthy persons from the enzootic region had EEEV-neutralizing antibodies. Our results suggest that humans are exposed but do not develop apparent infection with EEEV because of poor infectivity and/or avirulence of South American strains.

Seasonal distribution, biology, and human attraction patterns of culicine mosquitoes (Diptera: Culicidae) in a forest near Puerto Almendras, Iquitos, Peru.

This study was conducted as part of a field ecology study of arboviral activity in the Amazon Basin, Peru, to determine the taxonomy, frequency, seasonal, and vertical distributions of potential mosquito vectors. In addition, the relative efficiency of human-landing collections and dry ice-baited Centers for Disease Control (CDC)-type light traps was determined for collecting mosquitoes. A total of 70 species of mosquitoes from 14 genera were collected from June 1996 through December 1997 at a forested site near Puerto Almendras, approximately 20 km west-southwest of Iquitos, Peru. Three species [Psorophora (Janthinosoma) albigenu (Peryassu), Ochlerotatus (Ochlerotatus) fulvus (Wiedemann), and Ochlerotatus (Ochlerotatus) serratus (Theobald)] accounted for 70% of all mosquitoes captured in human-landing collections. Overall, biting activity occurred throughout the 24-h cycle but was higher during the daytime, primarily because of large populations of two day-biting species, Ps. albigenu and Oc. serratus. Oc. fulvus was active throughout the 24-h cycle but was more frequently collected during the evening. Oc. fulvus, Ps. albigenu, Culex (Melanoconion) pedroi Sirivanakarn & Belkin, and a mixture of Culex (Melaonoconion) vomerifer Komp, and Culex (Melanoconion) gnomatos Sallum, Huchings & Ferreira, accounted for 73% of the mosquitoes captured during darkness) by human collectors. In general, Ochlerotatus spp. and Psorophora spp. were more commonly captured in human-landing collections, whereas most Culex spp. were more frequently collected in the dry ice-baited CDC-type light traps. In general, mosquito populations were lowest from June through August when river levels were at their lowest. Two large population peaks occurred in November-December and in February-March as a result of "flood water" mosquito populations (e.g., Ps. albigenu). These data provide a better understanding of the taxonomy, population density, and seasonal distribution of potential mosquito vectors within the Amazon Basin region and allow for the development of appropriate vector and disease prevention strategies.

Endemic Venezuelan equine encephalitis in northern Peru.

Since Venezuelan equine encephalitis virus (VEEV) was isolated in Peru in 1942, >70 isolates have been obtained from mosquitoes, humans, and sylvatic mammals primarily in the Amazon region. To investigate genetic relationships among the Peru VEEV isolates and between the Peru isolates and other VEEV strains, a fragment of the PE2 gene was amplified and analyzed by single-stranded conformation polymorphism. Representatives of seven genotypes underwent sequencing and phylogenetic analysis. The results identified four VEE complex lineages that cocirculate in the Amazon region: subtypes ID (Panama and Colombia/Venezuela genotypes), IIIC, and a new, proposed subtype IIID, which was isolated from a febrile human, mosquitoes, and spiny rats. Both ID lineages and the IIID subtype are associated with febrile human illness. Most of the subtype ID isolates belonged to the Panama genotype, but the Colombia/Venezuela genotype, which is phylogenetically related to epizootic strains, also continues to circulate in the Amazon basin.

Diagnosis by Random Amplified Polymorphic DNA Polymerase Chain Reaction of Four Cryptic Species Related to Anopheles (Nyssorhynchus) albitarsis (Diptera: Culicidae) from Paraguay, Argentina, and Brazil

Random amplified poplyphormic DNA polymerase chain reaction (RAPED-PCR) analysis was applied to samples from widespread population of the poorly characterized Anopheles (Nyssorhynchus) albitarsis Lynch-Arribálzaga species complex, and 4 genetically differentiated species were distinguished. A screen of 65 random decamer oligonucleotide primers identified 12 primers, which produced 19 reproducible species-specific genetic markers and 4 markes common to 2 or more species. These markers were correlated in nearly all individuals of each species throughout the ranges sampled, including populations as far apart as 2,500 km. Each individual analyzed was from a different isofemale progeny brood, with associated morphological specimens. These specimens will facilitate studies to relate these species to previously reported chromosomal and enzymatic variation as well as to their feeding behavior and potential as malaria vector. We hypothesize that 3 of the species have recognized valid names: A. (Nys) albitarsis Lynch-Arribálzaga, An (Nys) marajora Galvão and Damasceno, and /an. (Nys) deaneorum Rosa-Freitas, whereas the is undescribed.

Infection of Anopheles darlingi fed on patients infected with Plasmodium vivax before and during treatment with chloroquine plus primaquine in Costa Marques, Rondônia, Brazil

Five patients with asexual and sexual parasites of Plasmodium vivax were treated orally with 600 mg chloroquine diphosphate (hour 0) followed with 300 mg at 8, 24 and 48 h later. Primaquine phospate, 15 mg, was administered concurrently at h 0 and 24 h intervals for 14 days. Anopheles darlingi were fed before the first dose (h-0.5) and 0.5, 1, 2, 4, 6, 8, 10, 12, 16, 20, 24, 36, 48, 60 and 72 h later. Mosquitoes were examined for oocysts on day 8 and for sporozoites on day 15 after infection. Four of the five patients studied were still infective to mosquitoes from 1-5 h after the first dose of chloroquine plus primaquine. One of these and one other patient, who vomited 15 min after the first dose, became inffective again at hours 10 and 12, respectively. Once produced, oocysts in mosquitoes fed on patients before, during and after chloroquine plus primaquine treatment appeared normal and produced sporozoite infected salivary glands. In view of these data , it is concluded that primaquine demonstrated rapid gametocytocidal activity and should be administred concurrently with chloroquine to reduce vivax malaria transmission

Seasonal distribution and diel biting patterns of culicine mosquitoes in Costa Marques, Rondônia, Brazil

A study of peridomestic man-biting culicines in the Amazon Basin was conducted from January through December, 1987. Fifteen species of mosquitoes from six genera were collected by volunters in all-night human-bait indoor and outdoor collections at five hoses in and near the town of Costa Marques, Rondônia, Brazil. Culex quinquefasciatus and members of the Mansonia titillans/indubitans Group comprised 61 and 33%, respectively, of all culcines collected from human-bait outside houses and 62 and 35%, respectively, of those collected from volunteers inside houses in the town. In rural areas, Cx. quinquefasciatus was less abundant and only comprised 2 and 5% of the culcines, respectively, collected inside and outside houses. Mansonia titillans/indubitans Group comprised 75% and 86% of the culicines collected inside and outside houses, respectively, from rural residences. Culex quinquefasciatus and members of Mn. titillans/indubitans Group were more endophilic than other culcines collected. Nocturnal and seasonal biting rhythms for the more common culcines are described

Biting behavior of anopheles mosquitoes in Costa Marques, Rondonia, Brazil

Para determinar o comportamento antropofilico e zoofilico dos anofelinos, foram capturados mosquitos na periferia e na zona urbana da Costa Marques, Rondônia, Brasil. Foram comparadas as capturas feiras à noite, com iscas bovinas e humanas, dentro e fora de casa. O Anopheles darlingi e o Anopheles deaneorum foram mais antropofilcios do que os outros anofelinos capturados. O restante das espécies anofelinas foi capturado mais freqüentemente nas iscas bofinas do que nas humans. Anopheles darlingi e Anopheles deaneorum foram capturados dentro de casa com mais freqüência do que as outras espécies anofelinas. Porém, quando a captura foi feita em casas com muitas aberturas nas paredes houve pouca diferença nas porcentagens de cada espécie sugadora de humanos dentro e fora de casa. Anopheles darlingi foi o mosquito capturado com mais freqüência, dentro e fora de casa, e apresentava maior antropofilia em relaçäo aos outros anofelinos presentes