Potential Mosquito Vectors for Shuni Virus, South Africa, 2014-2018.

Shuni virus is associated with neurologic and febrile illness in animals and humans. To determine potential vectors, we collected mosquitoes in South Africa and detected the virus in species of the genera Mansonia, Culex, Aedes, and Anopheles. These mosquitoes may be associated with Shuni virus outbreaks in Africa and emergence in other regions.

Anopheles atroparvus density modeling using MODIS NDVI in a former malarious area in Portugal.

Malaria is dependent on environmental factors and considered as potentially re-emerging in temperate regions. Remote sensing data have been used successfully for monitoring environmental conditions that influence the patterns of such arthropod vector-borne diseases. Anopheles atroparvus density data were collected from 2002 to 2005, on a bimonthly basis, at three sites in a former malarial area in Southern Portugal. The development of the Remote Vector Model (RVM) was based upon two main variables: temperature and the Normalized Differential Vegetation Index (NDVI) from the Moderate Resolution Imaging Spectroradiometer (MODIS) Terra satellite. Temperature influences the mosquito life cycle and affects its intra-annual prevalence, and MODIS NDVI was used as a proxy for suitable habitat conditions. Mosquito data were used for calibration and validation of the model. For areas with high mosquito density, the model validation demonstrated a Pearson correlation of 0.68 (p<0.05) and a modelling efficiency/Nash-Sutcliffe of 0.44 representing the model's ability to predict intra- and inter-annual vector density trends. RVM estimates the density of the former malarial vector An. atroparvus as a function of temperature and of MODIS NDVI. RVM is a satellite data-based assimilation algorithm that uses temperature fields to predict the intra- and inter-annual densities of this mosquito species using MODIS NDVI. RVM is a relevant tool for vector density estimation, contributing to the risk assessment of transmission of mosquito-borne diseases and can be part of the early warning system and contingency plans providing support to the decision making process of relevant authorities.

Immune reactivity to dengue and Aedes albopictus mosquitoes in the population from Macao, China, before dengue occurrence.

A serological survey was conducted in Macao, China, in 753 individuals, with the objective of looking for antibodies to the mosquito, Aedes albopictus (Skuse 1894) (Diptera: Culicidae), and to dengue, before the occurrence of any autochthonous dengue cases. Blood samples were collected at several public health services, a questionnaire was answered, and enzyme-linked immunosorbant assay (ELISA) and Western blot techniques were performed with extracts of mosquito head and thorax (HT). Anti-Aedes albopictus IgG antibodies were present in titres 1:10(2)-1:10(3) in 9%, and in titres 1:10(4)-1:10(5) in 42% of the sera tested. This reactivity was more frequent (59%) in the population which had resided only in Macao in the 2 years previous to the survey, as opposed to those that had also resided in other areas (50%). From the 230 reactive sera selected for immunoblot, 48 (21%) reacted with a wide range of proteins from above 224 kDa to 21 kDa, with different patterns according to individual sera. Proteins in the intervals 35.3-28.7 kDa and 28.7-21.1 kDa were labelled by the greatest number of sera, 15 and 19 respectively. The presence of anti-Aedes albopictus antibodies presented a statistical relation to skin reaction to mosquito bites, but immunoblot patterns did not. Anti-dengue IgG antibodies were found in 48% of the subjects, with a higher proportion in people who had resided out of Macao, or who were nationals from dengue-endemic neighboring countries. Anti-dengue reactivity was in agreement with anti-mosquito reactivity in half of the population. It would be interesting to see if this proportion has changed since dengue became endemic in Macao in 2001.

Species Composition and WNV Screening of Mosquitoes from Lagoons in a Wetland Area of the Algarve, Portugal.

The aim of this study was to evaluate mosquito abundance, species diversity, larval and adult population dynamics in seven lagoons integrated in the wetland coastal system of the Algarve, Portugal, in the summer of 2007, as well as the screening of these for West Nile virus (WNV). WNV has been isolated from mosquitoes in this region, in the summer of 2004, next to the putative area of infection of two linked human WN cases. Adult mosquitoes were collected with CDC traps baited with CO(2), and potential breeding sites were surveyed for immature stages. Morphological identification of 1,432 adult mosquitoes and 85 larvae revealed the presence of 10 species: Anopheles atroparvus, Anopheles algeriensis, Coquillettidia richiardii, Culex modestus, Culex pipiens, Culex theileri, Culex univittatus, Culiseta longiareolata, Aedes caspius, and Aedes detritus. Adult mosquito peak densities were recorded in July, contrasting with null larval breeding in the same month in the surveyed biotopes. Most abundant species were C. pipiens (52%), C. theileri (29%), and A. caspius (11%). Lagoon Salgados and Quinta das Salinas, exhibited the highest similarity of culicid fauna, despite being most distant from each other, Female mosquitoes (1,249 specimens) screened by RT-PCR, did not reveal WNV products. However, previous detection of WNV activity in this area, susceptible to re-introductions, demands for continued vigilance.

A possible key molecule for the invasion of the Plasmodium berghei ookinetes into the midgut epithelium of Anopheles gambiae mosquitoes.

BACKGROUND: In order to identify molecules necessary for the invasion of the mosquito midgut epithelium by plasmodia, interaction assays between both these structures were devised. MATERIALS AND METHODS: Enrichment of Plasmodium berghei ookinetes was first carried out using a double 5-17% gradient Nycodenz cushion, which resulted in an enrichment factor of over 800%. Viability of these ookinetes was confirmed by membrane feeding mosquito infection assays, showing no decrease in infection prevalence or intensity, and suggesting that putative surface proteins necessary for the invasion were unaffected. RESULTS: Protein interaction assays between mosquito midgut and ookinete extracts were optimized yielding Anopheles gambiae mosquito midgut proteins of >220, 200 and 48 kDa that could bind biotinylated P. berghei ookinete extracts, and P. berghei ookinete proteins of 48-45 kDa that could bind biotinylated An. gambiae midgut proteins. Using an An. gambiae midgut biotinylated extract linked to a streptavidin-agarose matrix, P. berghei ookinete proteins of approximately 116, 45 and 21 kDa were obtained. This protein chromotography pull-down assay was reproducibly repeated and spots from 2D eletrophoretic separation were analysed by mass spectrometry. For one spot, a significant match with a putative erythrocyte binding protein from P. falciparum (Pf EBA-165) was obtained. This protein belongs to the erythrocyte binding superfamily of the merozoite stage that is involved in the invasion process of the erythrocytes. CONCLUSION: Our findings suggest that there is a possibility that a homologue of Pf EBA-165 takes part in the ookinete recognition and invasion process of the mosquito midgut by plasmodia ookinetes.

[Spider poisoning in Portugal: fact or myth?]. / Envenenamento por aranhas em Portugal: verdade ou mito?

There are 800 known species of spiders in Portugal. Of these, only two may cause any kind of medical condition: the Mediterranean black-widow (Latrodectus tredecimguttatus) and the violin spider (Loxosceles rufescens). Both are relatively common in the country, the latter inclusively in urban areas. It is frequent in Portugal for some types of necrotic lesión to be attributed to spider bites. However, as in the rest of the world, evidences are often circumstantial. Most probably, some of the reported cases may in fact represent misdiagnoses of serious conditions such as infections by Streptococcus group A or Methicillin resistant Staphylococcus aureus. The correct diagnosis of spider poisoning must always be submitted to the following steps: (1) confirmation or observation of the biting, with verification of medical signs compatible with it; (2) the spider should be captured immediately or right after the bite, dead or alive; (3) identification of the spider by a taxonomist. It is extremely important that the medical community does not associate any necrotic lesion with a spider bite based on merely circumstantial evidence. Doing it is to neglect the real cause of such condition and to delay the effective cure. In reality, given their rarity, spider bite lesions should be relegated to the end of the differential diagnostic list of necrotic skin lesions.

Bioecology and vectorial capacity of Aedes albopictus (Diptera: Culicidae) in Macao, China, in relation to dengue virus transmission.

Until 2001, the Chinese Territory of Macao had not registered any autochthonous dengue cases, despite the abundance of Aedes albopictus (Skuse), a known vector. This work describes a bioecological characterization of the local Ae. albopictus adult population, with the purpose of estimating the receptivity of Macao to dengue introduction. In the wet seasons of 1997 and 1998 and the dry season of 1998, Ae. albopictus was the most abundant human-biting mosquito. Daily biting rates of 314 mosquitoes per person were recorded in the wet season with a reduction to 94 in the dry season. Ae. albopictus was mainly exophagic and exophilic and had a human blood index of 44%. The parity rate of field-collected mosquitoes was 57%. Daily survival rate ranged from 91 to 97%. Estimates of vectorial capacity ranged from 144 to 880, depending on what parameter values were used. These estimates indicated a great receptivity for the introduction of dengue viruses, as the 2001 outbreak came to prove.

West Nile virus in Southern Portugal, 2004.

West Nile virus (WNV) genomic RNA was detected by reverse transcription-polymerase chain reaction (RT-PCR) in six out of 57 mosquito pools collected in Southern Portugal, during the summer of 2004, yielding an infection rate (IR) of 2.8/1,000 mosquitoes. Phylogenetic analysis of a 217-nucleotide fragment of the NS5 coding region, amplified from Culex pipiens s.l. and Culex univittatus unfed females, demonstrated a close relationship with WNV strains circulating in the Mediterranean basin (Italy, 1998; France, 2000; Morocco, 2003). The data in this short report demonstrate the presence of WNV in mosquitoes in Southern Portugal and the need of permanent surveillance for viral activity within the country.

Induced immunity against the mosquito Anopheles stephensi (Diptera: Culicidae): effects of cell fraction antigens on survival, fecundity, and plasmodium berghei (Eucoccidiida: Plasmodiidae) transmission.

Two subeellular fractions from the midgut of the malaria mosquito Anopheles stephensi (Liston) were used to immunize BALB/c mice. Mice were subsequently infected with the rodent malaria parasite Plasmodium berghei (Vineke & Lips), and the effects of anti-mosquito immunity on mosquito survival and fecundity and on parasite transmission were investigated. Mosquitoes were infected directly from mice (in vivo) or by feeding cultured ookinetes through a membrane (in vitro). Infections were monitored by counting oocysts on the midgut wall. Microvilli extracts induced a strong and partially specific antibody reaction against the midgut, which was manifest as decreased survival in in vivo fed mosquitoes and reduced fecundity in both kinds of feeding. Antisera against microvilli reduced the mean intensity of P. berghei oocysts when fed in vitro, while mosquitoes fed antiserum against basolateral plasma membranes in vivo, showed higher oocyst burdens.