[First report of Aedes albopictus in areas of Mata Atlantica, Recife, PE, Brazil]

Infestation of an endemic arbovirus area by sympatric populations of Aedes aegypti and Aedes albopictus in Brazil

BACKGROUND Aedes aegypti and Aedes albopictus are the most important arbovirus vectors in the world. OBJECTIVES This study aimed to investigate and compare the infestation pattern of these species in a neighbourhood of Recife, Brazil, endemic for arboviruses in 2005 (T1) and 2013 (T2). METHODS Infestation, distribution and relative abundance of these sympatric species were recorded by egg collection using a network of 59 sentinel ovitraps (s-ovt) at fixed sampling stations for 12 months in T1 and T2. FINDINGS A permanent occupation pattern was detected which was characterised by the presence of egg-laying females of one or both species with a high ovitrap positivity index (94.3 to 100%) throughout both years analysed. In terms of abundance, the total of eggs collected was lower (p < 0.005) in T2 (146,153) than in T1 (281,103), although ovitraps still displayed a high index of positivity. The spatial distribution showed the presence of both species in 65.1% of the 148 s-ovt assessed, while a smaller number of traps exclusively contained Ae. aegypti (22%) or Ae. albopictus (13.2%) eggs. MAIN CONCLUSIONS Our comparative analysis demonstrated the robustness of the spatial occupation and permanence of Ae. aegypti and Ae. albopictus populations in this endemic urban area.

The Asian tiger mosquito in Brazil: Observations on biology and ecological interactions since its first detection in 1986

Aedes (Stegomyia) albopictus is a mosquito originating from the Asian continent, which was detected in the Americas in 1985 and Brazil in 1986. Due to its rapid expansion throughout Brazil, this species has already been reported in 26 of the 27 federative units of Brazil. In this review, we evaluate some of the biological, epidemiological and ecological characteristics of Ae. albopictus through critical analysis of their importance in the pathogen transmission dynamics, since its first record in the country. We show that immature forms of this species are frequently found in artificial breeding sites whereas females exhibit anthropophilic behavior despite its eclecticism on blood feeding. In addition, Ae. albopictus shows advantages in interspecific competition with Ae. aegypti for both immature and adult stages. Taking together, these aspects as well as its vector competence indicate that Ae. albopictus could act as a bridge vector between sylvatic and urban pathogen transmission cycles. We conclude by pointing to the need of continuous surveillance of Ae. albopictus in Brazil and raise several questions that still need to be answered.

First report of Aedes albopictus infected by Dengue and Zika virus in a rural outbreak in Brazil

In Brazil, Dengue (DENV) and Zika (ZIKV) viruses are reported as being transmitted exclusively by Aedes aegypti in urban settings. This study established the vectors and viruses involved in an arbovirus outbreak that occurred in 2019 in a rural area of Espírito Santo state, Brazil. Mosquitoes collected were morphologically identified, sorted in samples, and submitted to molecular analysis for arboviruses detection. Phylogenetic reconstruction was performed for the viral sequence obtained. All 393 mosquitoes were identified as Aedes albopictus. DENV-1 genotype V was present in one sample and another sample was positive for ZIKV. The DENV-1 clustered with viruses that have circulated in previous years in large urban centers of different regions in Brazil. This is the first report of A. albopictus infected by DENV and ZIKV during an outbreak in a rural area in Brazil, indicating its involvement in arboviral transmission. The DENV-1 strain found in the A. albopictus was not new in Brazil, being involved previously in epidemics related to A. aegypti, suggesting the potential to A. albopictus in transmitting viruses already circulating in the Brazilian population. This finding also indicates the possibility of these viruses to disperse across urban and rural settings, imposing additional challenges for the control of the diseases.

An unsettling explanation for the failure of skatole-baited ovitraps to capture Culex mosquitoes

Culex mosquitoes are primarily found in temperate and tropical regions worldwide where they play a crucial role as main vectors of filarial worms and arboviruses. In Recife, a northeast city in Brazil, high densities of Culex quinquefasciatus are often found in association with human populated areas. In marked contrast to another part of the city, field tests conducted in the neighborhood of Sítio dos Pintos showed that trapping of mosquitoes in skatole-baited ovitraps did not differ significantly from captures in control (water) traps. Thus, classical and molecular taxonomic approaches were used to analyze the Culex species circulating in Sítio dos Pintos. Results obtained from both approaches agreed on the cocirculation of Culex quinquefasciatus and Culex nigripalpus in three different areas of this neighborhood. What was initially considered as an unexpected failure of this lure turned out to be a more unsettling problem, that is, the first report in Recife of Culex nigripalpus, a vector of Venezuelan equine encephalitis virus and West Nile virus. Unplanned urbanization processes close to remnants of the Atlantic forest, such as observed in Sítio dos Pintos, may have contributed to the introduction of Cx. nigripalpus in urban areas.

Culicidae fauna (Diptera: Culicidae) survey in urban, ecotonal and forested areas, from the Moreno municipality - Pernambuco State, Brazil

INTRODUCTION

Mosquitoes are vectors of several pathogens in tropical regions. However, information on Culicidae in the northeast region of Brazil is scarce despite many municipalities having environmental conditions favorable for these insects.

METHODS

We collected mosquitoes monthly for one year from urban, ecotonal, and ecological reserve areas in Moreno, Brazil, by using CDC Miniature light traps, aspiration, ovitraps, and liquid suction.

RESULTS

We collected 1,401 insects in the Culicidae family. Fifteen species of seven genera of Culicidae were identified and five specimens were identified only at the genus level.

CONCLUSIONS

There is a wide diversity of mosquito species in the sampled areas, some of which are important for human health.

Insecticide susceptibility of Aedes albopictus and Ae. aegypti from Brazil and the Swiss-Italian border region

BACKGROUND

Aedes aegypti and Ae. albopictus are two highly invasive mosquito species, both vectors of several viruses, including dengue, chikungunya and Zika. While Ae. aegypti is the primary vector in the tropics and sub-tropics, Ae. albopictus is increasingly under the public health watch as it has been implicated in arbovirus-transmission in more temperate regions, including continental Europe. Vector control using insecticides is the pillar of most control programmes; hence development of insecticide resistance is of great concern. As part of a Brazilian-Swiss Joint Research Programme we set out to assess whether there are any signs of existing or incipient insecticide resistance primarily against the larvicide Bacillus thuringiensis svar. israelensis (Bti), but also against currently applied and potentially alternative insecticides in our areas, Recife (Brazil) and the Swiss-Italian border region.

METHODS

Following World Health Organization guidelines, dose-response curves for a range of insecticides were established for both colonized and field caught Ae. aegypti and Ae. albopictus. The larvicides included Bti, two of its toxins, Cry11Aa and Cry4Ba, Lysinibacillus sphaericus, Vectomax CG®, a formulated combination of Bti and L. sphaericus, and diflubenzuron. In addition to the larvicides, the Swiss-Italian Ae. albopictus populations were also tested against five adulticides (bendiocarb, dichlorodiphenyltrichloroethane, malathion, permethrin and λ-cyhalothrin).

RESULTS

Showing a similar dose-response, all mosquito populations were fully susceptible to the larvicides tested and, in particular, to Bti which is currently used both in Brazil and Switzerland. In addition, there were no signs of incipient resistance against Bti as larvae were equally susceptible to the individual toxins, Cry11Aa and Cry4Ba. The field-caught Swiss-Italian populations were susceptible to the adulticides tested but DDT mortality rates showed signs of reduced susceptibility.

CONCLUSIONS

The insecticides currently used for mosquito control in Switzerland and Brazil are still effective against the target populations. The present study provides an important reference as relatively few insecticide susceptibility surveys have been carried out with Ae. albopictus.

Updating the geographical distribution and frequency of Aedes albopictus in Brazil with remarks regarding its range in the Americas

The geographical distribution of Aedes albopictus in Brazil was updated according to the data recorded across the country over the last eight years. Countrywide house indexes (HI) for Ae. albopictus in urban and suburban areas were described for the first time using a sample of Brazilian municipalities. This mosquito is currently present in at least 59% of the Brazilian municipalities and in 24 of the 27 federal units (i.e., 26 states and the Federal District). In 34 Brazilian municipalities, the HI values for Ae. albopictus were higher than those recorded for Ae. aegypti, reaching figures as high as HI = 7.72 in the Southeast Region. Remarks regarding the current range of this mosquito species in the Americas are also presented. Nineteen American countries are currently infested and few mainland American countries have not confirmed the occurrence of Ae. albopictus. The large distribution and high frequency of Ae. albopictus in the Americas may become a critical factor in the spread of arboviruses like chikungunya in the new world.

Ecological aspects of mosquitoes (Diptera: Culicidae) in the gallery forest of Brasília National Park, Brazil, with an emphasis on potential vectors of yellow fever

INTRODUCTION

We analyzed the vertical and monthly distributions of culicid species in the gallery forest of Brasília National Park, with an emphasis on the potential vectors of yellow fever (YF).

METHODS

Between September 2010 and August 2011, mosquitoes were captured on the ground and in the canopy of the forest for five consecutive days per month, from nine to 15 hours. The mosquitoes were examined to verify natural infection with flaviviruses by isolation in Aedes albopictus Skuse, 1864 cells followed by indirect immunofluorescence.

RESULTS

We identified 2,677 culicids distributed in 29 species. Most of the mosquitoes were captured at ground level (69%) during the rainy season (86%). The most abundant species were Sabethes (Sabethes) albiprivus Theobald, 1903; Limatus durhamii Theobald, 1901; Haemagogus (Conopostegus) leucocelaenus Dyar & Shannon, 1924; Haemagogus (Haemagogus) janthinomys Dyar, 1921; Aedes (Ochlerotatus) scapularis Rondani, 1848; Psorophora (Janthinosoma) ferox Von Humboldt, 1819; and Aedes (Ochlerotatus) serratus Theobald, 1901. Limatus durhamii, Limatus durhamii, Psorophora ferox, Aedes scapularis and Aedes serratus showed significant differences (p<0.05) in their habitat use. Limatus durhamii was found more often in the canopy, unlike the other species. During the rainy season, the most abundant species were Sa. albiprivus, Haemagogus leucocelaenus and Limatus durhamii. During the dry season, the potential YF vectors exhibited a very low frequency and abundance, except Aedes scapularis and Aedes serratus. No flavivirus was detected in the 2,677 examined mosquitoes.

CONCLUSIONS

We recommend continued and systematic entomological monitoring in areas vulnerable to the transmission of YF in the Federal District of Brazil.

Seasonal variation of potential flavivirus vectors in an urban biological reserve in northeastern Brazil

Although yellow fever (YF) has not been reported on the eastern coast of Brazil since 1942, there was a reemergence of dengue fever in Brazil in 1987 due to the reintroduction of Aedes aegypti (L.). To assess areas of potential risk for transmission of vector-borne diseases, a surveillance system was placed in a large Atlantic Forest reserve in Natal, Rio Grande do Norte, Brazil, where in 2004 unexplained epizootics were reported among marmosets. The etiologic agent causing the mortality in marmosets has not been identified. Wyeomyia bourrouli Lutz, Haemagogus leucocelaenus Dyar & Shannon, Ae. aegypti, Aedes albopictus (Skuse), Ochlerotatus scapularis Rondani, Ochlerotatus serratus Theobald, Ochlerotatus taeniorhynchus Wiedemann, Culex quinquefasciatus Say, and Limatus durhami Theobald were collected in the park and in the proximity of the households adjacent to the park. Seasonal abundance fluctuation was significant for Ae. aegypti, Ae. albopictus, Ochlerotatus scapularis (Rondani), and Hg. leucocelaenus. Eggs of Ae. aegypti, Ae. albopictus, and Hg. leucocelaenus were more frequently found at the conclusion of the rainy season. A significant negative correlation between the number ofAe. albopictus collected and temperature was observed (r = -0.50), i.e., for each 10C increase in temperature, the number of specimens collected decreased eight-fold. The findings reported herein reinforce the need for a sustainable arboviral surveillance program in this area to decrease the potential risk of emergence of vector borne diseases as YF.

[Spatial distribution of Aedes albopictus in the southern area of Mato Grosso do Sul State, Brazil]

OBJECTIVE

To investigate the spatial distribution of Aedes albopictus population to provide input for developing sampling plans and supporting decision making on the control of this vector in field sampling.

METHODS

A study was carried out in an urban area that has a vestige of primary vegetation, 20 km away from Dourados, Midwestern Brazil. Ten samplings were conducted between January 28, 2003 and April 9, 2003, using ovitraps which were monitored once a week, and distributed in a fixed sample area with 10 collection points for each sampling 300 m away from each other. Aggregation indexes were calculated and adjusted to the following theoretical frequency distribution: negative binomial, positive binomial and Poisson's.

RESULTS

The sample variance was higher than the sampling mean, resulting in mean-variance indexes above the unit (32.066, 29.410, 14.444, 58.840, 56.042, 111.262, 70.140, 50.701, 93.221 and 8.481). Morisita's index was also statistically above the unit in all samplings (6.275, 3.947, 1.484, 3.725, 3.014, 5.450, 3.214, 3.886, 3.954 and 5.810), and K parameter ranged 0 and 8 (0.174, 0.309, 1.867, 0.332, 0.449, 0.203, 0.408, 0.314, 0.306 and 0.200). The Chi-square test for adjustment to the negative binomial distribution, positive binomial distribution, and Poisson's distribution was not statistically significant.

CONCLUSIONS

Ae. albopictus population in the studied municipality showed an aggregated standard spatial distribution. This means that when individual vectors are found in a certain site, it is likely that other vectors can be found in the proximities, recommending insecticide spraying for vector control in this site without requiring sampling other sites in this same locality.

Ecosystem approaches and health in Latin America

Important environmental changes that have become increasingly pronounced in the last two centuries and that are seriously affecting human health require the development of integrated and participatory scientific approaches that can result in proposals for institutional and public policy changes. The purpose of this article is to offer some elements that can contribute to a line of reflection based on studies with ecosystem approaches in the Latin America context. The authors begin with a brief description of current scientific literature in public health that links ecosystems and human health in Latin America; next, they describe and compare the two prevailing trends that form the basis for the theoretical and methodological debates on ecosystem approaches; they also review the empirical research in Latin America or concerning Latin American countries in which an ecosystem approach has been adopted. The results point to limited scientific output on the interface between ecosystems and human health; aspects involving public participation and implementation of institutional changes and public policies are still in a rather incipient stage.

A scenario for invasion and dispersal of Aedes albopictus (Diptera: Culicidae) in New Zealand

To date, there has been no confirmed, indigenously acquired case of arthropod-borne viral disease in New Zealand, but this may change in the near future due to the presence of exotic vectors and regular influx of infected humans. The risk of a disease outbreak may be aggravated if other exotic mosquito vectors become established, in particular Aedes albopictus (Skuse), a species that has already been intercepted several times in New Zealand. In this study, the possible means of invasion and dispersal of Ae. albopictus in northern New Zealand are discussed, along with the factors that should facilitate its establishment in the event it evades border controls.

Exotic mosquitoes in New Zealand: a review of species intercepted, their pathways and ports of entry

A review was carried out to identify the exotic mosquito species intercepted in New Zealand to 2004, together with their origins, pathways and ports of entry into the country. A total of 171 interceptions have been recorded since 1929. There was little or no taxonomic information available for many, but at least 27 exotic species not yet established in New Zealand have been intercepted, including important disease vectors such as Aedes albopictus, Aedes aegypti and Culex annulirostris. Of 152 interception records with a described origin, 100 (66%) have originated from the South Pacific, 42 (28%) from Australia alone, while Japan was the likely source for 22 (15%) interceptions and has become the main source of exotic mosquitoes since the 1990s. Aircraft have clearly been the main vessel for invading mosquitoes with 94 (62%) of 151 cases with a described entrance pathway, but that pattern has changed greatly in the past 15 years, with 51 (82%) of 62 interceptions occurring on ships. Auckland, New Zealand's largest city, has been the main port of entry for invaders (75/93; 81%). The data indicate that it is somewhat fortunate that New Zealand has only four exotic mosquito species established. It is necessary, therefore, to adopt comprehensive exotic species monitoring and border surveillance, with particular emphasis on incoming ships and their cargo, in order to stop further mosquito invasions that could potentially lead to future outbreaks of mosquito-borne diseases.

Aedes albopictus in an area of Misiones, Argentina

Until early 1998 the presence of Aedes albopictus had never been detected in Argentina. During April of the same year, few individuals of this species were recorded in 33 breeding sites found in 25 out of 161 inspected houses in the city of Eldorado, Province of Misiones. The homogeneous spatial distribution of the proliferation foci suggests the existence of a generalized infestation in this locality during the study period.

Vector competence of Brazilian Aedes aegypti and Ae. albopictus for a Brazilian yellow fever virus isolate

Because the potential urban yellow fever (YF) mosquito vectors Aedes aegypti and Ae. albopictus are at historical highs in Brazil, both in terms of density and geographical range, we assessed the risk of an urban YF epidemic in Brazil. We evaluated and confirmed in a laboratory setting the vector competence of Brazilian Ae. aegypti for a currently circulating strain of YF virus, and investigated the potential for Brazilian Ae. albopictus to transmit YF.