Ecology of phlebotomines (Diptera, Psychodidae) in rural foci of leishmaniasis in tropical Brazil

INTRODUCTION: This work aimed to study the community structure of sandflies, with regard to the richness, constancy, abundance, and monthly frequency of the species with a focus on the transmission of leishmaniasis. METHODS: The study was conducted in the rural villages of Bom Jardim and Santa Maria, situated on the edge of a tropical rain forest in the municipality of São Jose de Ribamar, Maranhão, Brazil. The phlebotomines were captured in the intradomiciles and peridomiciles of each village, with Centers for Disease Control (CDC) light traps set in 10 homes in each village, for 1 year, once a month, from 18h to 6h. RESULTS: We collected 1,378 individuals of 16 sandfly species. The capture success rate was higher in Bom Jardim (0.61 specimens/hour/trap) than that of Santa Maria (0.35/specimens/hour/trap). The sandflies were more abundant in the peridomiciles (86.1%) and in the rainy season (77%). Five species were considered constants (occurring in more than 50% of samples), 5 accessory (25%-50%), and 6 accidental (<25%). The most abundant species were Lutzomyia longipalpis (59.7%) and L whitmani (28%). The permutation analysis showed differences between the species composition of the villages and no separation between the intradomicile and peridomicile of each village. The species that most contributed to the dissimilarity between the light traps of the 2 villages were L. longipalpis, L. whitmani, and L. evandroi, contributing to 80.8% of the variation among groups. CONCLUSIONS: The high level of richness and abundance of species and the presence of competent vectors throughout the year and around houses justify the occurrence of leishmaniasis cases reported in the area.

Triatomines in dwellings and outbuildings in an endemic area of Chagas disease in northeastern Brazil

INTRODUCTION: The present study identified the triatomines collected in intra and peri-domestic environments, observed the occurrence of Trypanosoma cruzi infection in triatomines and correlated this information with housing conditions and the fauna associated with the rural areas of the City of Itabaianinha, located in the State of Sergipe, Brazil. METHODS: Quarterly visits were conducted between March 2009 and March 2010, and the homes to be visited for the active search of insects were determined by random selection. In each housing unit, the insects were collected by a manual search with a metal clip and flashlight to inspect openings and cavities, with a collection time of one hour/home/individual. The Pirisa® dislodge chemical was used to force the insects to leave their ecotopes. Analysis of the intestinal contents of triatomines was performed in the laboratory to establish the presence of Trypanosomatidae. RESULTS: Of the 103 dwellings surveyed, 17.5% were infested with Panstrongylus megistus. The village of Mutuca exhibited the highest infestation rate (38.1%). All the villages with relevant infestation rates were situated in the northern area of the city. The highest percentage of vector infection was found in the village of Água Boa (56.5%). The rural dwellings were found to be primarily brick or wooden house with or without roughcast or plastered walls, and the outbuilding most frequently associated with triatomines was the chicken run. CONCLUSIONS: These results emphasise the need for broader vector control and surveillance and for educational campaigns in the context of the Chagas Disease Control Program.

Serologic survey of hantavirus in a rural population from the northern State of Mato Grosso, Brazil

INTRODUCTION: Hantavirus is a genus of ribonucleic acid (RNA) viruses included in the family Bunyaviridae. Hantaviruses are rodent-borne zoonoses that, in the last 18 years, became an emergent public health problem in the Americas, causing a severe cardiopulmonary syndrome. This disease has no specific treatment and has a high case fatality. The transmission of hantavirus to man occurs by inhaling aerosols of rodent excreta. The aim of this study was to determine the prevalence of antibodies to hantavirus in the population of the rural settlement of Tupã in the county of Marcelândia, state of Mato Grosso, Brazil. METHODS: The participants of the serologic survey were visited at their homes and selected randomly among the settlement population. Blood samples of the participants were collected by venopuncture. The serum samples were tested by an IgG-ELISA using an N recombinant protein of Araraquara hantavirus as antigen, using the protocol previously established by Figueiredo et al. RESULTS: IgG antibodies to hantavirus were detected in 7 (13%) of the 54 participants. The positivity was higher among men. It was observed that there was an association of seropositivity to hantavirus within the participants born in the south of Brazil. CONCLUSIONS: The results suggest that, in this rural area, everyone is exposed to the same risk of becoming infected with hantavirus, and, therefore, there is a need to intensify surveillance activities and education of the local people to prevent this viral infection.

New focus of active transmission of Chagas disease in indigenous populations in the Peruvian Amazon basin

Introduction Several cases of acute Chagas disease (ACD) have been reported in the Peruvian Amazon basin. Methods The objective was to describe and investigate 6 ACD cases in children from indigenous Amazon communities in the province of Datem del Marañón in Loreto department (2006-2010). Results The mean age was 3.6 years. All patients had fever, 4/6 hepatomegaly, 2/6 splenomegaly, and 5/6 had trypomastigotes of Trypanosoma cruzi on thick smears. The fatality rate was 33.3%. Rhodnius pictipes and Rhodnius robustus adults were found inside the homes and in the peri-domiciles. Conclusions All cases reported were isolated cases. We report a new focus of ACD in indigenous populations.

Pressao Arterial na Adolescencia, Adipocinas e Inflamacao no Adulto Jovem. Estudo do Rio de Janeiro

Fundamento: O impacto pressão arterial (PA) na adolescência sobre outros fatores de risco cardiovascular em adultos jovens é importante para a prevenção primária. Objetivo: Avaliar a PA, índices antropométricos, perfil metabólico e inflamatório de jovens estratificados pelo comportamento da sua PA obtida há 18 anos. Métodos: Avaliaram-se 116 indivíduos, sendo 63 homes, pertencentes ao estudo do Rio de Janeiro (seguimento 17,76 ± 1,63 anos) em dois momentos: A1 (12,40 ± 1,49 anos) e A2 (30,09 ± 2,01 anos). Os 116 indivíduos foram divididos em dois grupos: GN (n = 71), PA normal em A1; e GH (n = 45): PA anormal em A1. A PA, o peso, a altura e o índice de massa corporal (IMC) foram obtidos em A1 e A2. Em A2, acrescentaram-se a circunferência abdominal (CA) e variáveis laboratoriais, metabólicas e inflamatórias. Resultados: 1) Os grupos não diferiram quanto à idade e sexo; 2) Em A2, GH apresentou maiores médias de peso, IMC, PA, insulina, HOMA-IR (p < 0,001), leptina (p < 0,02), Apolipoproteína B100 e A1 (p < 0,02), relação Apolipoproteína B100 / Apolipoproteína A1 (p < 0,010), maiores prevalências de sobrepeso/obesidade (p < 0,001), da CA aumentada (p < 0,001) e de hipertensão arterial (p < 0,02); 3) Não houve diferença entre os grupos para as variáveis inflamatórias; 4) Houve correlação positiva da PA em A1 com a PA, o IMC, e com a insulina, a leptina e o HOMA-IR em A2 (p < 0,05). Conclusões: A PA na adolescência se associou a maiores valores de PA, variáveis antropométricas e metabólicas na fase adulta jovem, mas não a variáveis inflamatórias.

Indirect immunofluorescence test in new world Leishmaniasis: serological and clinical relation-ship

The indirect immunofluorescence test (IF) for anti-Leishmania antibodies (IgC and IgM) was performed with sera form the following groups of individuals: 214 cutaneous leishmaniasis patients, 28 healthy subjects with positive Montenegro's skin test (MST), 29 healthy subjects with negativeMST and 16 visceral leishmaniasis patients. The first four groups came from a suburban area of Rio de Janeiro (Jacarepaguá) where cutaneous leishmaniasis caused by Leishmania braziliensis braziliensis is endemic. It was observed that IF-IgM titers were significantly higher amongst the cutaneous leishmaniasis patients with less than four months of disease as compared to those with longer periods and that IF-IgG titers were significantly higher in patients with multiple lesions as compared to those with single lesions. The visceral leishmaniasis patients had IF-IgG titers significantly higher than those from cutaneous leishmaniasis patients. A group of 28 individuals selected amongst the 214 cutaneous leishmaniasis patients had their IF-titers (IgG and IgM) compared to those of the two control groups of healthy subjects from the endemic area, respectively with positive and negative MST. Significantly higher titers of IF-IgG and IF-IgM were found in the group with active disease. The same group of patients showed IF-IgG titers significantly lower at the end of the antimonial therapy than those observed during this tratment.

Urban ecology of Triatoma infestans in San Juan, Argentina

This study was performed in an urban neighborhood of the capital city of the province of San Juan, Argentina. Erected as a housing complex, the place consists of 768 flats distributed in buildings of three and seven floors each. A survey was carried out in 33% of the dwellings, enquiring about the number of Triatoma infestans found indoors, stage of the bug development - nymph or adult - and how these insects had entered their homes. Adult T.infestans were found on all floors; 163 people (64%) had found them at least once, and 130 (51%) several times. Dispersal flight seems to have been the main mechanism of infestation by adult bugs in this area, and a total of 51% of the surveyed inhabitants reported that the insects had flown into their flats.

House dust mites in Brazil - an annotated bibliography

House dust mites have been reported to be the most important allergen in human dwellings. Several articles had already shown the presence of different mite species at homes in Brazil, being Pyroglyphidae, Glycyphagidae and Cheyletidae the most important families found. This paper is an annotated bibliography that will lead to a better knowledge of house dust mite fauna in Brazil.

Phlebotomine sand flies (Diptera: Psychodidae) associated with the appearance of urban leishmaniasis in the city of Sincelejo, Colombia

Although once associated only with rural areas, the American leishmaniasis vectors now appear to be associated also with urban and suburban areas of the Neotropics. Following the appearance of the first autochthonous visceral and cutaneous leishmaniasis cases in the urban area of the city of Sincelejo, Colombia, a preliminary entomological survey of the sand fly species composition was performed using Shannon and CDC light traps. A total of 486 sand flies representing six Lutzomyia species were collected. L. evansi, L. panamensis and L. gomezi, known vectors of Leishmania spp. were the predominant sand fly species around dwellings. The finding of these species in relation to the appearance of the first cases of leishmaniasis in the city mentioned is discussed.

Geometric morphometric differences between Panstrongylus geniculatus from field and laboratory

The finding of Panstrongylus geniculatus nymphs inside a house in northeastern Antioquia, Colombia, and the reports related to their increasing presence in homes suggest the need for surveillance methods for monitoring the invasion processes. We analyzed the morphological differences between a wild population and its laboratory descendants, using the techniques of geometric morphometry, with the idea that such differences might parallel those between sylvatic and synanthropic populations. The analyses over five generations showed differences in size but not in shape. Head size and wing size were both reduced from sylvatic to laboratory populations, but the decrease in head size occurred only up to the second generation while the decrease in wing size proceeded up to the fifth generation. In contrast, although a decrease in sexual size dimorphism has been proposed as a marker of colonization in human dwellings, we did not detect any significant loss of dimorphism between sexes of P. geniculatus over the five generations studied. We conclude that size changes may have a physiological origin in response to a change of ecotopes, but more than five generations may be required for the expression of permanent morphological markers of human dwellings colonization.

Feeding and defaecation behaviour of Triatoma patagonica (Del Ponte, 1929) (Hemiptera: Reduviidae)

Among the vectors of Chagas disease, Triatoma patagonica is a species in the process of adaptation to the human environment being recently registered in urban and suburban zones. However, its importance as a vector of Chagas disease is unknown. The aim of this work was to evaluate two aspects of vectorial competence: the feeding behaviour and the defaecation pattern. These processes were studied in females of T. patagonica fed ad libitum on a restrained pigeon. The results showed that the blood meal size was negatively correlated with the time of first defaecation (r = -0.42). The first defaecation was emitted before the first 10 min and defaecations during feeding were frequent. A total of 73% of females, defaecated during the first 30 min post-feeding. These results suggest that if this species subsequently colonizes the domicile, it would be capable of transmitting Trypanosoma cruzi.

Active transmission of human chagas disease in Colima Mexico

Despite efforts to eradicate American trypanosomiasis (AT) and Chagas disease from the Americas, there are still areas of active transmission that can eventually become a source of reinfection in previously controlled regions. Mexico could be one of those areas, where there are no formal preventive control programs despite the presence of communities infested by Triatominae bugs infected with Trypanosoma cruzi. This study explored the prevalence of T. cruzi infection in 405 habitants of 17 communities in the state of Colima, on the Pacific Mexican coast, through a seroepidemiological probabilistic survey. The results revealed a point seroprevalence of 2.4% positive for anti-T. cruzi. In addition, 2 clinical cases of chronic and 2 of acute Chagas disease were detected in the explored communities. These findings confirm the risk of active transmission of AT in Western Mexico, especially in rural and suburban communities infested with intra-domestic triatominae, where control programs should be implemented.

Environmental management for the control of Triatoma dimidiata (Latreille, 1811), (Hemiptera: Reduviidae) in Costa Rica: a pilot project

An ecological control method, using environmental management operations, based on biological and behavioral characteristics of Triatoma dimidiata (Latreille, 1811), was implemented as a pilot project in an area of Costa Rica where the bug is prevalent. The sample was represented by 20 houses with peridomestic colonies (two also had indoor infestation), divided in two equivalent groups of 10 each. In one group we intervened the houses, i.e. all objects or materials that were serving as artificial ecotopes for the bugs were removed, and the second group was used as control houses. After a year of periodic follow up, it became evident that in those houses with a modified environment the number of insects had decreased notoriously even after the first visits and this was more evident after a period of 12.5 to 13.5 months in which no insects were detected in eight of the houses. It also became clear that in this group of houses, recolonization by wild bugs from the surrounding areas, became more difficult, probably due to the absence of protection from bug predators. In the control houses, with the exception of three in which the inhabitants decided to intervene on their own, and another house with a peculiar situation, the insect populations remained the same or even showed a tendency to increase, as confirmed at the end of the experiment. We believe that the method is feasible, low costing and non contaminating. It could be used successfully in other places where T. dimidiata is common and also in countries where other species colonize peridomestic areas of homes. Environmental management of this kind should seek the participation of the members of the communities, in order to make it a more permanent control measure.

Related factors to human toxocariasis in a rural community of Argentina

The objective of this study was to evaluate the relationship between toxocariasis frequency and demographic, environmental, sanitary variables, eosinophylia, and other intestinal parasites in a rural population of Argentina. Serological examination of 100 individuals was carried out by using ELISA technique for the detection of anti-toxocara antibodies. Eosinophiles in peripheral blood, presence of intestinal parasites, and demographic, environmental, and socio-cultural data were evaluated. Eighty-one feces samples of dogs belonging to the studied people were analyzed to detect eggs of Toxocara canis. Thirty of them were from 30 dogs and 51 were pools from dog feces. Samples of dirt from around the homes (n: 47) and from public park (n: 4) were taken. To determine the associations, the c² and Fisher tests were used. The seroprevalence was 23%. Eosinophilia in peripheral blood was detected in 86.95% seropositive individuals and in 37.66% seronegative individuals (p < 0.001, OR = 11.03). Of the 23 people with positive serology, 69.56% had at least one intestinal parasite. All individuals with positive serology had dogs in their homes. Among the dog owners there was a significant association between the presence of anti-toxocara antibodies and home flooding. Eggs of T. canis were detected in the feces of 5/81 dogs and three of these dogs belonged to individuals with positive serology. Eggs of Toxocara spp. were found in 41.17% of the dirt samples, eight of which came from the area surrounding the homes of individuals with positive serology (p = 0.032; OR = 4.36). Taking into account all the variables influencing the frequency of toxocariasis in this population, the implementation of Public Health programs specifically focused on anti-parasitic treatment of dogs is recommended.

Microsatellite characterization of Plasmodium falciparum from symptomatic and non-symptomatic infections from the Western Amazon reveals the existence of non-symptomatic infection-associated genotypes

In Western Amazon areas with perennial malaria transmission, long term residents frequently develop partial immunity to malarial infection caused either by Plasmodium falciparum or P. vivax, resulting in a considerable number of non-symptomatically infected individuals. For yet unknown reasons, these individuals sporadically develop symptomatic malaria. In order to identify if determined parasite genotypes, defined by a combination of eleven microsatellite markers, were associated to different outcomes - symptomatic or asymptomatic malaria - we analyzed infecting P. falciparum parasites in a suburban riverine population. Despite of detecting a high degree of diversity in the analyzed samples, several microsatellite marker alleles appeared accumulated in parasites from non-symptomatic infections. This result may be interpreted that a number of microsatellites, which are not directly related to antigenic features, could be associated to the outcome of malarial infection. The result may also point to a low frequency of recombinatorial events which otherwise would dissociate genes under strong immune pressure from the relatively neutral microsatellite loci.