Effects of temperature on the rate of increase of Stomoxys calcitrans and Stomoxys niger niger (Diptera: Muscidae) from La Réunion island

Adult survival and reproduction were compared between two Stomoxys species that co-occur in La Reunion, the cosmopolitan Stomoxys calcitrans (L.), and the tropical Stomoxys niger niger Macquart. In a first experiment, mean longevity and fecundity were determined at five constant temperatures from 15 to 35 degrees C, after development at the same temperatures. Adult longevity was greatest at 20 degrees C in S. calcitrans and at 15 degrees C in S. niger. Adult S. niger survived longer than adult S. calcitrans, especially at 15 degrees C. At 35 degrees C, all flies died within 3 d. Reproduction occurred only within the 20-30 degrees C range, and S. niger laid more eggs than S. calcitrans. In both species, lifetime fecundity tended to decrease when temperature increased, because of the shortening of the oviposition period. In a second experiment, adults were maintained at 15 degrees C after development at 25 degrees C. The higher temperature during development significantly increased adult longevity in S. calcitrans but not in S. niger. Reproduction occurred at 15 degrees C, with notable fecundity in S. calcitrans (22 eggs per female) but not in S. niger (<1 egg per female). Using previous results on immature survival and developmental time in the two species, several life history parameters were compared at each temperature. Generation time decreased with increasing temperature and was highly similar in both species. Concurrently, the intrinsic rate of increase (r) increased with temperature from 15 to 30 degrees C. At 15 degrees C, r was higher in S. calcitrans, but within the 20-30 degrees C range, r was higher in S. niger. The results suggest 1) S. niger has evolved a strategy of survival without any reproduction during the tropical winter, in contrast with S. calcitrans that breeds more continuously; and 2) S. niger may outnumber S. calcitrans in warm areas, at least when development occurs in media of poor quality.     

Genetic structure and gene flow along an altitudinal gradient among two stomoxyine species (Diptera: Muscidae) on La Réunion Island

Seasonal variations of insect population sizes are often dramatic, particularly in temperate regions and at altitudes where the climatic conditions are unfavorable to insect development during the winter. Decline of population size (or bottlenecks) and founder events may reduce the genetic variability and may create genetic differentiation between populations by drift and founder effects, but this reduction of genetic diversity is strongly influenced by gene flow between populations. In this study, we determined the population genetic structure for two stomoxyine species (Diptera: Muscidae), Stomoxys calcitrans (L.) and Stomoxys niger niger Macquart, which co-occur in dairy barns along an altitudinal gradient on La Réunion island. Using microsatellite markers, we quantified the genetic variation within and among populations for different altitudes. This study displays that, contrary to expectations, genetic diversity is not correlated with altitude and that genetic differentiation is not larger among high-altitude populations than among low-altitude populations. These results attest to the small drift and founder effects in high-altitude populations despite drastic decreases in population size during the winter. Furthermore, at the island scale, the populations of S. calcitrans were slightly differentiated, but those of S. niger niger were not. Together, the results revealed large levels of gene flow on La Réunion Island despite the dramatic geographic barriers, and they emphasize the importance of considering agricultural practices to restrict the dispersal of stomoxyines.     

Inventaire actualisé des moustiques (Diptera : Culicidae) de l’île de La Réunion, océan Indien

A literature analysis coupled with new entomological surveys conducted between 2009 and 2012 led to changes in the list of mosquito species present on the island of La Réunion. Using morphological criteria, Orthopodomyia arboricollis is replaced by Or. reunionensis. On the basis of morphometrical and genetic criteria, Culex univittatus is replaced by Cx. neavei. Cx. poicilipes, which was already reported missing 40 years ago, has not been found again. Anopheles arabiensis is confirmed as the only species of the Gambiae complex present on the island. Thus, twelve species are currently known. For each of them, elements of taxonomic, biological and medical interest are listed. An. arabiensis is a major vector of human Plasmodium (last case of indigenous malaria in 1967). In the Indian Ocean, Aedes albopictus and Ae. aegypti both are competent for transmitting dengue and chikungunya viruses. In Africa, Cx. quinquefasciatus transmits Wuchereria bancrofti and Cx. neavei transmits the Sindbis virus; both species also transmit the West Nile virus. Cx. tritaeniorhynchus is the major vector of Japanese Encephalitis virus in Asia. Two species are endemic (Ae. dufouri and Or. reunionensis), the ten other ones are also found in Madagascar and on the African continent (An. coustani, An. arabiensis, Ae. fowleri, Cx. tritaeniorhynchus, Cx. neavei, Cx. insignis, Lutzia tigripes), with three of them having also a cosmopolitan distribution (Ae. aegypti, Ae. albopictus and Cx. quinquefasciatus). Among the twelve recorded taxa, eight species are anthropophilic, three are supposedly zoophilic and one is a predatory species. No new invasive anthropophilic species did settle on the island. Updated identification keys of larval and adult stages are proposed.     

A review of the dynamics and severity of the pandemic A(H1N1) influenza virus on Réunion Island, 2009

On Reunion Island, in response to the threat of emergence of the pandemic influenza A(H1N1)2009 virus, we implemented enhanced influenza surveillance from May 2009 onwards in order to detect the introduction of pandemic H1N1 influenza and to monitor its spread and impact on public health. The first 2009 pandemic influenza A(H1N1) virus was identified in Réunion on July 5, 2009, in a traveller returning from Australia; seasonal influenza B virus activity had already been detected. By the end of July, a sustained community pandemic virus transmission had been established. Pandemic H1N1 influenza activity peaked during week 35 (24–30 August 2009), 4 weeks after the beginning of the epidemic. The epidemic ended on week 38 and had lasted 9 weeks. During these 9 weeks, an estimated 66 915 persons who consulted a physician could have been infected by the influenza A(H1N1)2009 virus, giving a cumulative attack rate for consultants of 8.26%. Taking into account the people who did not consult, the total number of infected persons reached 104 067, giving a cumulative attack rate for symptomatics of 12.85%. The crude fatality rate (CFR) for influenza A(H1N1)2009 and the CFR for acute respiratory infection was 0.7/10 000 cases. Our data show that influenza pandemic did not have a health impact on overall mortality on Réunion Island. These findings demonstrate the value of an integrated epidemiological, virological and hospital surveillance programme to monitor the scope of an epidemic, identify circulating strains and provide some guidance to public health control measures.     

HTLV-I infection in the South West Indian Ocean islands, particularly in La Réunion and the Seychelles

Data on HTLV-I are scarce in several Southwest Indian Ocean islands except for La Réunion and The Seychelles. The two cases of HTLV-I have been confirmed by Western-Blot in La Réunion, among blood donors. In Seychelles (87 400 inhabitants in 2012), where blood donors and some other cases are screened, HTLV-I was confirmed with a line immune assay in 43 persons and at least 10–20 patients are known to have tropical spastic paraparesia or adult T-cell lymphoma associated with HTLV-I. In the south-west Indian Ocean, a possibly important other issue may be co-infection of HTLV-1 with the Strongyloides stercoralis roundworm, which is endemic in all countries of the region and which can sometimes lead to severe symptomatic infestation.     

Phlebotomine sand flies (Diptera: Psychodidae) and Leishmania infection in Gafanhoto Park, Divinópolis, Brazil

The potential of Gafanhoto Park as an American cutaneous leishmaniasis (ACL) focus was evaluated by examination of sand fly vectors of the Leishmania parasite. This forest remnant is located in a periurban area of Divin6polis, Brazil, where autochthonous cases of ACL have been reported. Sand fly populations were monitored over a 2-yr period (2006-2008) by using light traps (HP and Shannon). During systematic collections with HP traps, 824 specimens in total (342 males and 482 females) of 21 species were captured. Most prevalent species were as follows: Brumptomyia brumpti (Larrouse), Lutzomyia aragaoi (Costa Lima), Lutzomyia lutziana (Costa Lima), Lutzomyia sordellii (Shannon & Del Ponte), and Lutzomyia whitmani (Antunes & Coutinho). Using Shannon traps, 257 specimens representing 15 species were collected (159 females and 98 males), with a high prevalence of L. whitmani and Lutzomyia neivai (Pinto), both vectors of Leishmania braziliensis (Vianna). To ascertain the level of natural infection, a sample of females captured in Shannon traps was assayed for the presence of Leishmania by using polymerase chain reaction-restriction fragment length polymorphism, where 39% of insects were positive. The most infected species was L. whitmani (29 sand flies; 18.2%), followed by L. neivai (21; 13.2%), Lutzomyia christenseni (Young & Duncan) (five; 3.1%), Lutzomyia pessoai (Coutinho & Barreto) (three; 1.9%), L. aragaoi (one; 0.6%), Lutzomyia fischeri (Pinto) (one; 0.6%), Lutzomyia lenti (Mangabeira) (one; 0.6%), L. lutziana (one; 0.6%), and Lutzomyia monticula (Costa Lima) (one; 0.6%). The finding of potential and incriminated vectors naturally infected with Leishmania reinforces the need of epidemiologic surveillance in the area.     

Evaluation of the vectorial capacity of Anopheles arabiensis (Diptera:Culicidae) on the island of Réunion: an approach to the health risk of malaria importation in an area of eradication]

Following intensive control measures, malaria was eradicated from La Réunion Island (Indian Ocean) in 1979. However, potential vectors remain in coastal areas and, each year Public Health Services detect some imported cases from surrounding countries. Anopheles arabiensis is the only species which can be responsible for local transmission though its brief life cycle and its exophilic and zoophilic behaviour were found to be key elements in maintaining the eradication status of the disease on the island. Its vectorial capacity was measured at different seasons and in different areas with a view to assessing the health risks due to imported malaria and suggesting a more pertinent strategy of vector control.     

Prevalence of hepatitis A, B, C virus markers in Réunion (south hospital and Saint Pierre prison)

We studied the prevalence of Hepatitis A, B, C in different groups in the population of the South of Reunion Island. The aims of this study were the following: to estimate the prevalence of Hepatitis C virus (HCV) (anti-HCV antibodies) and Hepatitis B virus (HBV) (anti-HBc, HBs Ag and anti-HBs) in a population of 1455 women, who delivered in the Centre hospitalier Sud Reunion (CHSR), to estimate the prevalence of these two viruses in a population selected for risk factors (100 prisoners), to estimate the prevalence of Hepatitis A in a group of 400 persons (aged 0 to 19) hospitalised in CHSR since 1st January 1998 (100 for each 5-year age bracket), to research risks factors in these populations and immunity. The overall prevalence of anti-HCV was 0.14% in pregnant women and risk factor associated was found in 28.9% of this population (2.9% history of transfusion, 0.21% drug users). In the group of prisoners seroprevalence was 2%, far below that of prisoners in France. Anti-HCV seroprevalence is weak in Reunion Island and very inferior to seroprevalence in the French population as in other Indian Ocean islands. This is due to the low risk of parenteral transmission. Anti-HBc was found in 90 serum samples from women (overall prevalence 6.35%) and of these 90 positive samples, 9 were positive for HBs Ag (overall prevalence 0.63%), 68 were positive for anti-HBs (4.81%) and 22 (1.54%) were anti-HBc isolated (without HBs Ag and anti-HBs). The overall prevalence of anti-HBs was 62.8%. In the population of 100 prisoners, 2 were HBs Ag positive, 10 anti-HBc positive (2 anti-HBc isolated, 2 associated with HBs Ag, 6 with anti-HBs). The prevalence of anti-HBs was 22%. The major risk factor observed in this population of prisoners was tattooing and/or piercing (46%). These results show that: Reunion island is an area of low endemicity for HBV virus. The measure of protective inoculation is well followed. i.v. drug abuse and previous transfusion are weak routes of transmission. In the group aged 0 to 19, overall prevalence of anti-HAV was 11.9% with the highest rate found among 15 to 19 year-olds (25%). Seroprevalence falls with socio-economic progress. At the present time, the endemic is intermediate in Reunion Island. Given immunity levels within the young population, there is a risk of outbreak. This risk is due to the conditions in Reunion Island, but also to people who travel to other Indian Ocean countries where endemicity is high. It is thus very important that a vaccination strategy be determined.     

Genetic diversity of KIR natural killer cell markers in populations from France, Guadeloupe, Finland, Senegal and Réunion

Killer cell immunoglobulin-like receptors (KIRs) belong to a diverse family of natural killer (NK) cell receptors recognizing human leukocyte antigen (HLA) class I molecules. Due to this functional link, KIR molecules are expected to display a high polymorphism, such as their HLA ligands. Moreover, many studies conducted in mouse and human models have shown that NK-KIR receptors play an important role in haematopoietic stem cell transplantation (HSCT). A beneficial impact of peculiar KIR ligand (HLA) mismatching has been reported suggesting a role to this combinatory HLA-KIR polymorphism. It is thus important to investigate KIR diversity in various human populations. To this end, we used polymerase chain reaction-sequence-specific primers to evaluate KIR gene in five selected populations (France, Guadeloupe, Senegal, Finland and Réunion). Genotypic and haplotypic frequencies were computed, as well as genetic distances and dendrogram (phylip package). These data illustrate the genetic relationship of these five populations through the KIR polymorphism. Results revealed a wide diversity in KIR gene frequencies in Guadeloupe and Réunion, and a high specificity in Senegal. The obtained dendrogram indicated small genetic distances between France, Guadeloupe and Réunion as well as between France and Finland. Senegal showed a distant genetic relationship with the other countries and, interestingly, an inverted ratio of coding/non-coding (KIR2DS4/1D) alleles compared with Caucasians. These data expose the broad diversity in KIR genes worldwide and show that KIR genes are pertinent tools in human population genetics. If the role of KIR donor-recipient incompatibilities is confirmed, KIR diversity according to ethnicity should be taken into account during the selection of HSCT donors.     

Laboratory colonization of Anopheles aquasalis (Diptera: Culicidae) in Belém, Pará, Brazil

Anopheles aquasalis Curry, a coastal malaria vector with a Neotropical distribution, was collected from Belém, Pará state, Brazil, and 500 adults per cage were maintained at the Instituto Evandro Chagas insectary at 26 -30 degrees C and 80 -90% RH, where they fed on a 10% domestic sugar solution and blood from white mice. Oviposition of the parental generation (P) occurred in fresh water in dark cups introduced into mosquito cages. After eclosion, 100 larvae per pan were reared in artesian well water (salinity 0.04 g liter(-10) and fed ground fish food until pupation. After force mating in the F1 generation, the eight subsequent generations were free mating. Mean larval mortality was < 1%, and the mean developmental time from eclosion to emergence was 7.7 d (F1), 7.6 d (F2), 8 d (F3), and 7.5 d (F4). The maximum daily production of pupae (from the fourth generation on) occurred on day 6 postoviposition.     

Adult mortality and blood feeding behavioral effects of α-amyrin acetate, a novel bioactive compound on in vivo exposed females of Anopheles stephensi Liston (Diptera: Culicidae)

The effect of α-amyrin acetate on mortality and blood feeding behavior in females of Anopheles stephensi was assessed by in vivo exposure on treated guinea pig skin. In vivo exposure to α-amyrin acetate caused mosquito knock down in the form of rapidly and normally reversible paralysis and the subsequent record at the end of a 24 h, revealed mortality rates of females increased from 0.0% (Control) to 76.9% at 1.6% α-amyrin acetate, the highest concentration which implies the contact toxicity of the α-amyrin acetate received through the sensitive parts of test species. The mean probing time responses significantly increased (P?相似文献   

Feeding patterns of Haemagogus capricornii and Haemagogus leucocelaenus (Diptera: Culicidae) in two Brazilian states (Rio de Janeiro and Goiás)

We present the identification of bloodfeeding sources of Haemagogus (Haemagogus) capricornii Lutz and Haemagogus (Conopostegus) leucocelaenus (Dyar & Shannon) (Diptera: Culicidae) from different regions of Brazil, as analyzed by precipitin tests. Anti-sera for bird, bovine, equine, human, opossum, and rodent were used. Two hundred one mosquitoes were examined (147 Hg. leucocelaenus and 54 Hg. capricornii), of which 177 reacted for some anti-serum. For Hg. leucocelaenus, 86 (68.3%) reacted to one blood source, 38 (30.2%) to two sources, and two (1.6%) to three sources; the combinations of bird + human (18.4%), bird + rodent (15.8%), and bird + marsupial (15.8%) were the most frequent. For Hg. capricornii, 34 (66.7%) reacted to one blood source; combinations bird + rodent (37.5%) and bird + marsupial (25%) were the most frequent combinations. Mosquito preference for bloodfeeding sources was different in these areas, possibly because of the availability of sources. This diversity of sources can have important epidemiological implications.     

Genetic diversity of HLA system in two populations from Querétaro,Mexico: Querétaro city and rural Querétaro

We studied HLA class I (HLA-A, -B) and class II (HLA-DRB1, -DQB1) alleles by PCR-SSP based typing in 88 Mexicans from the state of Querétaro living in the city of Querétaro (N = 45) and rural communities (N = 43), to obtain information regarding allelic and haplotypic frequencies. We find that the most frequent haplotypes in the state of Querétaro include seven Native American, two European and one Asian haplotype. Admixture estimates revealed that the main genetic components in the state of Querétaro are Native American (51.82 ± 4.42% by ML; 42.61% of Native American haplotypes) and European (48.18 ± 3.55% by ML; 46.02% of European haplotypes), with a virtually absent African genetic component (0.00 ± 4.25% by ML; 4.55% of African haplotypes).     

Épidémie de grippe A(H1N1)2009 à La Réunion: expérience de la consultation ambulatoire dédiée, juillet–septembre 2009

From July 6 to September 29, 2009, 380 patients were seen as out-patients for flu-like illness, and 355 files (253 women and 102 men) were available for retrospective analysis. Mean age was 32 years. 158 patients, including 22 with A(H1N1)2009 influenza had underlying medical conditions: pregnancy (N = 87), asthma (N = 37), obesity (N = 17). Most frequent symptoms of A(H1N1)2009 influenza patients were fever (97% of the patients), cough (94%), rhinorrhea (59%), myalgia (56%), headache (36%). A nasopharyngeal swab for influenza virus detection by PCR was performed on 118 patients including 27 pregnant women. 44 patients, including 40 A(H1N1)2009 influenza cases were tested positive. 21 patients were referred to the emergency department for further tests or treatment and 31 patients were admitted as in-patients. 20 pregnant women were referred for further obstetrical monitoring; none presented with respiratory failure or foetal distress. None of the patients were admitted to the ICU or died.     

Genetic diversity of HLA system in two populations from Chiapas,Mexico: Tuxtla Gutiérrez and rural Chiapas

We studied HLA class I (HLA-A, -B) and class II (HLA-DRB1, -DQB1) alleles by PCR-SSP based typing in 173 Mexicans from the state of Chiapas living in the city of Tuxtla Gutiérrez (N = 52) and rural communities (N = 121), to obtain information regarding allelic and haplotypic frequencies. We found that the most frequent haplotypes in Chiapas include 12 Native American and one European haplotype. Admixture estimates revealed that the main genetic components in Chiapas are Native American (71.61 ± 0.58% by ML; 53.16% of Native American haplotypes) and European (26.39 ± 5.05% by ML; 25.86% of European haplotypes), and a less prominent African genetic component (2.00 ± 5.20% by ML; 9.77% of African haplotypes).     

Comments on Nickels and Howard (2004) “dissociating effects of number of phonemes,number of syllables,and syllable complexity on word production in aphasia: It's the number of phonemes that counts”

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