Multi-scale analysis of the associations among egg, larval and pupal surveys and the presence and abundance of adult female Aedes aegypti (Stegomyia aegypti) in the city of Merida, Mexico.

Despite decades of research, there is still no agreement on which indices of Aedes aegypti (Stegomyia aegypti) (Diptera: Culicidae) presence and abundance better quantify entomological risk for dengue. This study reports the results of a multi-scale, cross-sectional entomological survey carried out in 1160 households in the city of Merida, Mexico to establish: (a) the correlation between levels of Ae. aegypti presence and abundance detected with aspirators and ovitraps; (b) which immature and egg indices correlate with the presence and abundance of Ae. aegypti females, and (c) the correlations amongst traditional Aedes indices and their modifications for pupae at the household level and within medium-sized geographic areas used for vector surveillance. Our analyses show that ovitrap positivity was significantly associated with indoor adult Ae. aegypti presence [odds ratio (OR) = 1.50; P = 0.03], that the presence of pupae is associated with adult presence at the household level (OR = 2.27; P = 0.001), that classic Aedes indices are informative only when they account for pupae, and that window screens provide a significant level of protection against peridomestic Ae. aegypti (OR = 0.59; P = 0.02). Results reinforce the potential of using both positive collections in outdoor ovitraps and the presence of pupae as sensitive indicators of indoor adult female presence.

Spatial variation in the effects of size and age on reproductive dynamics of common coral trout Plectropomus leopardus.

The effects of size and age on reproductive dynamics of common coral trout Plectropomus leopardus populations were compared between coral reefs open or closed (no-take marine reserves) to fishing and among four geographic regions of the Great Barrier Reef (GBR), Australia. The specific reproductive metrics investigated were the sex ratio, the proportion of vitellogenic females and the spawning fraction of local populations. Sex ratios became increasingly male biased with length and age, as expected for a protogyne, but were more male biased in southern regions of the GBR (Mackay and Storm Cay) than in northern regions (Lizard Island and Townsville) across all lengths and ages. The proportion of vitellogenic females also increased with length and age. Female P. leopardus were capable of daily spawning during the spawning season, but on average spawned every 4·3 days. Mature females spawned most frequently on Townsville reserve reefs (every 2·3 days) and Lizard Island fished reefs (every 3·2 days). Females on Mackay reefs open to fishing showed no evidence of spawning over 4 years of sampling, while females on reserve reefs spawned only once every 2-3 months. No effect of length on spawning frequency was detected. Spawning frequency increased with age on Lizard Island fished reefs, declined with age on Storm Cay fished reefs, and declined with age on reserve reefs in all regions. It is hypothesized that the variation in P. leopardus sex ratios and spawning frequency among GBR regions is primarily driven by water temperature, while no-take management zones influence spawning frequency depending on the region in which the reserve is located. Male bias and lack of spawning activity on southern GBR, where densities of adult P. leopardus are highest, suggest that recruits may be supplied from central or northern GBR. Significant regional variation in reproductive traits suggests that a regional approach to management of P. leopardus is appropriate and highlights the need for considering spatial variation in reproduction where reserves are used as fishery or conservation management tools.

Age estimation and validation for South Pacific albacore Thunnus alalunga.

Validated estimates of age are presented for albacore Thunnus alalunga, sampled from a large part of the south-western Pacific Ocean, based on counts of annual opaque growth zones from transverse sections of otoliths. Counts of daily increments were used to estimate the location of the first opaque growth zone, which was completed before the first assumed birthday. The periodicity of opaque zones was estimated by marginal increment analysis and an oxytetracycline mark-recapture experiment. Both validation methods indicated that opaque zones formed over the austral summer and were completed by autumn to winter (April to August). The direct comparison of age estimates obtained from otoliths and dorsal-fin spines of the same fish indicated bias, which was assumed to be due to poor increment clarity and resorption of early growth zones in spines, resulting in imprecise age estimates. As such, age estimates from otoliths are considered to be more accurate than those from spines for T. alalunga. This is consistent with results for a growing number of tropical and temperate tuna Thunnini species. It is recommend that validated counts of annual growth zones from sectioned otoliths is used as the preferred method for estimating age-based parameters for assessment and management advice for these important stocks.

Comparative biology of tropical Lethrinus species (Lethrinidae): challenges for multi-species management.

Life-history characteristics of six tropical Lethrinus species sampled from the Great Barrier Reef World Heritage Area were compared. Two species groups were identified based on fork length (LF ): large species with maximum LF > 640 mm (longface emperor Lethrinus olivaceus, yellowlip emperor Lethrinus xanthochilus and spangled emperor Lethrinus nebulosus) and small species with maximum LF < 480 mm (Pacific yellowtail emperor Lethrinus atkinsoni, pink ear emperor Lethrinus lentjan and ornate emperor Lethrinus ornatus). Lifespan was not correlated with LF . Early growth for all species was rapid and similar during the first few years of life, but coefficients of the von Bertalanffy growth function varied considerably among species. Growth also differed between sexes for L. atkinsoni. Reproductive characteristics varied among species, with peak periods of spawning occurring in November to December for L. atkinsoni, July to August for L. nebulous, September to October for L. olivaceus and a protracted season for L. lentjan, although fewer samples were available for the last two species. Sex-specific LF and age distributions and gonad histology of L. lentjan were suggestive of a functional protogynous reproductive pattern, as observed in other lethrinids. Gonad histology indicated non-functional protogynous hermaphroditism for L. atkinsoni and L. nebulosus. The diversity of life histories among these closely related species emphasizes the difficulty in devising single management strategies appropriate for multi-species fisheries and illustrates the importance of understanding species-specific life histories to infer responses to exploitation.

Knowledge, attitudes and practices about leishmaniasis among cutaneous leishmaniasis patients in Aleppo, Syrian Arab Republic.

Cutaneous leishmaniasis (CL) is endemic in Aleppo and yet the knowledge, attitudes and practices (KAP) of CL patients in Aleppo has never been studied. We conducted a KAP study among 70 CL patients attending 4 clinics in Aleppo. Participants were interviewed at recruitment and then at the end of treatment to ascertain their views on access to treatment and the quality of care provided. The mean age of respondents was 32.3 (SD 12.4) years and 59% were female. Most respondents referred to the disease as "one-year sore", linked it to insect bites and believed it was not contagious. Most believed it was preventable by the use of bednets and insecticides and knew the treatment mode. Only 26 (37%) respondents completed the second part of the questionnaire after treatment. Most of these (80%) rated the quality of care as acceptable or better. Assessment f the quality as "bad" correlated with failure to complete follow-up.

Auxin and kinetin interaction in apical dominance.

The effects of auxin on the inhibition of lateral buds in decapitated bean plants are enhanced if kinetin is applied together with auxin. The uptake of (14)C-indoleacetic acid by the stumps of decapitated plants is increased in the presence of kinetin and leads to extensive transport of (14)C-indoleacetic acid in the stems. The increased bud inhibition resulting when auxin and kinetin are applied together may be due to greater amounts of auxin reaching the buds, but an alternative explanation is that metabolites are directed from the buds to the point of hormone application.

Auxin effects on the mobility of kinetin in the plant.

Kinetin (6-furfurylaminopurine) is generally considered to be relatively immobile within plants. Kinetin labeled with (14)C was applied to the stumps of decapitated bean plants, with or without simultaneous application of indoleacetic acid. Significantly greater amounts of kinetin moved downwards in the stem in the presence of added indoleacetic acid than in its absence.

A novel mode of arbovirus transmission involving a nonviremic host.

In nature, infected and uninfected arthropod vectors often feed together on an animal. In mimicking this scenario in the laboratory, uninfected vectors were found to acquire virus while cofeeding on the same host as infected vectors. However, the vertebrate host on which they fed did not develop detectable levels of virus in its blood. These observations were made with Thogoto virus, an influenza-like virus of medical and veterinary significance. Rhipicephalus appendiculatus ticks were used as the vector and guinea pigs as the vertebrate host. The results demonstrate that a vertebrate that is apparently refractory to infection by an arthropod-borne virus can still play an important role in the epidemiology of the virus, and they suggest a novel mode of arthropod-borne virus transmission.

Two Leishmania species circulating in the Kaleybar focus of infantile visceral leishmaniasis, northwest Iran: implications for deltamethrin dog collar intervention.

Leishmania infantum is the causative agent of infantile visceral leishmaniasis (IVL) in the Mediterranean Basin and, based on isoenzyme typing of a few isolates from patients and domestic dogs, this parasite was considered to predominate in the Kaleybar focus of IVL in northwest Iran. However, in the current investigation only one out of five sandfly infections was found to be L. infantum, based on PCR detection and sequencing of parasite internal transcribed spacer (ITS) rDNA infecting Phlebotomus perfiliewi transcaucasicus. The four other infections were of haplotypes of L. tropica, the causative agent of anthroponotic cutaneous leishmaniasis in the Middle East and a parasite occasionally detected in the viscera of dogs and patients in Iran and elsewhere. The widespread distribution of L. tropica in the Kaleybar focus suggests that this parasite is not a transient introduction. Kaleybar has been used for a deltamethrin dog collar intervention to reduce the biting rates of the vectors of L. infantum and this has significantly reduced the incidence of Leishmania infections both in children and the domestic dog, the usual reservoir host of IVL. The implications of finding L. tropica widespread in the heart of the intervention area are discussed. Extensive and intensive typing of natural Leishmania infections is a characteristic of epidemiological investigations in the Neotropics and the current report indicates that this will also be necessary in some regions of the Old World.

House-level risk factors for triatomine infestation in Colombia.

BACKGROUND: Chagas disease, transmitted domestically by triatomine bugs, is the most important vector-borne disease in Latin America. The association between triatomine infestation and housing characteristics was investigated based on a standardized survey in 41 971 houses in 15 Departments in Colombia. METHODS: Multivariate logistic regression was used to test for associations of two highly correlated infestation measures of infestation (householders reporting having seen triatomines inside the house, and sending triatomines to the survey team), with 15 household-level risk factors. Risks were measured relative to a reference category of houses with up to three inhabitants, area up to 50 m(2), unplastered adobe walls, thatch roof and no outbuildings or domestic animals. RESULTS: The probability of seeing triatomines was highest for households with over seven inhabitants (OR = 1.24, 95% CI 1.11-1.39), overhead storage space (OR = 1.16, 95% CI 1.03-1.32), grain shed (OR = 1.25, 95% CI 1.02-1.52), cats (OR = 1.27, 95% CI 1.14-1.42) and pigs (OR = 1.16, 95% CI 1.03-1.30). Lowest risks were in houses with wooden walls (OR = 0.46, 95% CI 0.34-0.61), fully plastered walls (OR = 0.78, 95% CI 0.68-0.88), roofs made of tiles (OR = 0.51, 95% CI 0.33-0.78) and flagstone floors (OR = 0.57, 95% CI 0.42-0.76). Results for householders returning triatomines support this set of risk factors, but with wider confidence intervals. CONCLUSIONS: Surveillance of a few easily assessed household characteristics provides an accurate, rapid assessment of house-level variation in risk. Measured effect sizes for specific structural characteristics could be used to maximize the cost-effectiveness of programmes to reduce vector infestation and interrupt Chagas disease transmission by improving house quality.

Reproductive benefits of no-take marine reserves vary with region for an exploited coral reef fish.

No-take marine reserves (NTMRs) are expected to benefit fisheries via the net export of eggs and larvae (recruitment subsidy) from reserves to adjacent fished areas. Quantifying egg production is the first step in evaluating recruitment subsidy potential. We calculated annual egg production per unit area (EPUA) from 2004 to 2013 for the commercially important common coral trout, Plectropomus leopardus, on fished and NTMR reefs throughout the Great Barrier Reef (GBR), Australia. Geographic region, NTMR status, fish size, and population density were all found to affect EPUA. The interactions among these factors were such that, EPUA on NTMR reefs compared to reefs open to fishing was 21% greater in the southern GBR, 152% greater in the central GBR, but 56% less in the northern GBR. The results show that while NTMRs can potentially provide a substantial recruitment subsidy (central GBR reefs), they may provide a far smaller subsidy (southern GBR), or serve as recruitment sinks (northern GBR) for the same species in nearby locations where demographic rates differ. This study highlights the importance of considering spatial variation in EPUA when assessing locations of NTMRs if recruitment subsidy is expected from them.

Efficacy of thermotherapy to treat cutaneous leishmaniasis caused by Leishmania tropica in Kabul, Afghanistan: a randomized, controlled trial.

BACKGROUND: Pentavalent antimony is the agent recommended for treatment of cutaneous leishmaniasis (CL). Its use is problematic, because it is expensive and because of the potential for drug-associated adverse effects during a lengthy and painful treatment course. METHODS: We tested the efficacy of thermotherapy for the treatment of CL due to Leishmania tropica in a randomized, controlled trial in Kabul, Afghanistan. We enrolled 401 patients with a single CL lesion and administered thermotherapy using radio-frequency waves (1 treatment of >or=1 consecutive application at 50 degrees C for 30 s) or sodium stibogluconate (SSG), administered either intralesionally (a total of 5 injections of 2-5 mL every 5-7 days, depending on lesion size) or intramuscularly (20 mg/kg daily for 21 days). RESULTS: Cure, defined as complete reepithelialization at 100 days after treatment initiation, was observed in 75 (69.4%) of 108 patients who received thermotherapy, 70 (75.3%) of 93 patients who received intralesional SSG, and 26 (44.8%) of 58 patients who received intramuscular SSG. The OR for cure with thermotherapy was 2.80 (95% confidence interval [CI], 1.45-5.41), compared with intramuscular SSG treatment (P=.002). No statistically significant difference was observed in the odds of cure in comparison of intralesional SSG and thermotherapy treatments. The OR for cure with intralesional SSG treatment was 3.75 (95% CI, 1.86-7.54), compared with intramuscular SSG treatment (P<.001). The time to cure was significantly shorter in the thermotherapy group (median, 53 days) than in the intralesional SSG or intramuscularly SSG group (median, 75 days and >100 days, respectively; P=.003). CONCLUSIONS: Thermotherapy is an effective, comparatively well-tolerated, and rapid treatment for CL, and it should be considered as an alternative to antimony treatment.

Evidence of discrete yellowfin tuna (Thunnus albacares) populations demands rethink of management for this globally important resource.

Tropical tuna fisheries are central to food security and economic development of many regions of the world. Contemporary population assessment and management generally assume these fisheries exploit a single mixed spawning population, within ocean basins. To date population genetics has lacked the required power to conclusively test this assumption. Here we demonstrate heterogeneous population structure among yellowfin tuna sampled at three locations across the Pacific Ocean (western, central, and eastern) via analysis of double digest restriction-site associated DNA using Next Generation Sequencing technology. The differences among locations are such that individuals sampled from one of the three regions examined can be assigned with close to 100% accuracy demonstrating the power of this approach for providing practical markers for fishery independent verification of catch provenance in a way not achieved by previous techniques. Given these results, an extended pan-tropical survey of yellowfin tuna using this approach will not only help combat the largest threat to sustainable fisheries (i.e. illegal, unreported, and unregulated fishing) but will also provide a basis to transform current monitoring, assessment, and management approaches for this globally significant species.

Extensive polymorphism at the Gp63 locus in field isolates of Leishmania peruviana.

Genetic diversity within and between tandemly arrayed copies of the Gp63 gene occurs in laboratory isolates of Leishmania spp., but the extent to which this represents natural genetic diversity has not been assessed. Here, the Gp63 locus is examined in 58 fresh isolates of L. peruviana, and clones derived from them, collected throughout the Peruvian Andes. Extensive polymorphism is observed, both in size of Gp63 containing chromosomes, and for restriction-fragment-length polymorphisms (RFLPs) at the Gp63 locus. All clones within an isolate are identical, including those with two distinct Gp63-hybridising chromosomal-sized pulsed-field gel electrophoresis (PFGE) bands, consistent with diploidy but with size differences in homologous chromosomes. For RFLP analysis, three enzymes were selected to cut within the coding region (PstI), in the intergenic region (SalI) and outside (EcoRI) the Gp63 gene cluster. PstI gave identical banding patterns across all isolates/clones. For EcoRI and SalI, all clones within an isolate were identical, but isolates were polymorphic for fragments at 13 (2-30 kb) and 8 (2.6-8.8 kb) different molecular mass locations generating 19 and 16 distinct RFLP patterns or genotypes for each enzyme, respectively. EcoRI restriction patterns, analysed by PFGE, were consistent with the presence of two clusters of Gp63 genes on each homologous chromosome, one contained within EcoRI fragments large enough to carry from 3 to 10 copies of the Gp63 gene, the second on fragments which could carry 1 or 2 copies of the gene. SalI patterns indicated variable restriction sites within clusters, but not within every intergenic region. A hierarchical analysis of variance of allele frequencies, expressed in terms of Wright's F-statistic, indicated significant barriers to gene flow at all levels, valleys within regions (north/south), villages within valleys, and individuals within villages. This extreme polymorphism at the Gp63 locus of L. peruviana demonstrates the great potential for generation of genetic diversity in parasite populations.

Is the domestic dog (Canis familiaris) a reservoir host of American cutaneous leishmaniasis? A critical review of the current evidence.

Originally associated with forested areas, the transmission cycle of American cutaneous leishmaniasis (ACL) has now adapted to the domestic environment in at least 9 Latin American countries. Several studies have suggested that the domestic dog (Canis familiaris), which is already incriminated as the primary reservoir host of zoonotic visceral leishmaniasis (ZVL), may have a reservoir role in the domestic transmission of human ACL caused by Leishmania braziliensis, L. panamensis, and L. peruviana. This article reviews more than 90 studies reporting ACL infections in dogs, and concludes that as yet there is only circumstantial evidence to support that claim. Almost no data are available on the infectiousness of dogs to sandfly vectors of ACL, and there are few indications that either dog ownership or dog abundance are risk factors for ACL. Nevertheless, it has been proposed that incidence of ACL in humans could be reduced by targeting infected dogs. While this control strategy has been used for many decades against ZVL in Latin America, Europe, and Asia, there is little evidence to demonstrate its effectiveness either in theory or in practice. Particular concerns over the sensitivity and specificity of diagnostic tools, low compliance rates among dog owners, and cost-effectiveness are likely to apply equally to ACL control.

Experimental studies on the transmission cycle of Thogoto virus, a candidate orthomyxovirus, in Rhipicephalus appendiculatus.

Thogoto (THO) virus, a candidate orthomyxovirus, replicated in and was transmitted by larvae, nymphs, and adults of the brown ear tick, Rhipicephalus appendiculatus. Larvae fed on viremic hamsters (10(7-8) PFU/ml blood) acquired an average of 10(2.5) PFU per tick. Following engorgement the titer dropped to 10(1.9) PFU on day 2 but increased by day 6 to 10(3.3) PFU. Virus survived transstadially in these ticks as demonstrated by the fact that, on day 10, newly moulted nymphs contained, on average, 10(3.5) PFU/tick. When 10 such infected nymphs were placed on a hamster a fatal infection of the animal developed involving a viremia of 10(6.7) PFU/ml blood. Another group of 6 infected nymphs did not elicit a detectable viremia in a hamster, or cause death. However the animal seroconverted to THO, virus indicating that virus transmission had occurred. Following acquisition of THO virus at the larval stage, virus was detected in adult ticks 138 days later. Uninfected nymphs fed on viremic hamsters acquired an average of 10(4) PFU/nymph. No virus was detected in the nymphs 4 days post-engorgement. Virus was, however, recovered by 6 days post-engorgement (10(4.7) PFU/nymph). Virus persisted transstadially as shown by the presence of an average of 10(3.4) PFU in newly moulted adults. Three groups of these infected adults (5-6 ticks/group) induced viremia in hamsters with blood titers of the order 10(2.8-3.5) PFU/ml. Virus persisted in engorged adults for up to 66 days following nymphal engorgement.(ABSTRACT TRUNCATED AT 250 WORDS)

A comparative field study of the relative importance of Lutzomyia peruensis and Lutzomyia verrucarum as vectors of cutaneous leishmaniasis in the Peruvian Andes.

A two-year field study of Andean cutaneous leishmaniasis (uta) in the valley of Purisima, Ancash Department, Peru has provided quantitative epidemiologic and entomologic evidence for the predominant role of Lutzomyia peruensis in the transmission of Leishmania peruviana in this endemic area. The monthly incidence in the valley was greatest in the wet season (from December to May), when Lu. peruensis was particularly endophilic. A significant correlation was detected between intradomiciliary (but not extradomiciliary) Lu. peruensis abundance and the monthly incidence of uta in the valley following a one-month time lag. In contrast, no significant correlation was detected between any measure of Lu. verrucarum abundance and the incidence of uta. Lutzomyia peruensis and Lu. verrucarum comprise more than 98% of all the sand fly captures made in this valley. The increase in incidence of uta with altitude, which reached a peak rate between 2,250 and 2,750 meters above sea level, was associated with an increase in the relative abundance of Lu. peruensis as compared with Lu. verrucarum. Seasonal and altitudinal variation was also detected in the peak time of activity for both sand fly species, a phenomenon that could significantly influence the transmission rate: later host-seeking sand flies being more likely to find sleeping, nondefensive, human hosts.

A comparative study of the infection thresholds of Thogoto virus in Rhipicephalus appendiculatus and Amblyomma variegatum.

Infection thresholds of Thogoto virus in 2 ixodid tick species, Rhipicephalus appendiculatus and Amblyomma variegatum, were compared. Thogoto virus has been isolated from naturally infected R. appendiculatus and A. variegatum in Central Africa, where both commonly parasitize the same hosts. No significant difference was found between the infection thresholds of Thogoto virus in the 2 species. The percentage of nymphs of both species infected by feeding on viremic hamsters was directly correlated with the time between host inoculation and tick engorgement. The blood titers in infected hamsters increased each day during the 3-4 day viremia until the hamsters died. The percentage of nymphs infected correlated with the viremic titer on the final day of engorgement (the time of maximum blood uptake). The 5% infection threshold for nymphs of R. appendiculatus and A. variegatum was estimated as 10(2.8) and 10(2.7) plaque forming units (PFU)/ml viremia, respectively. The prevalence of infection approached 100% for blood titers greater than 10(6.3) PFU/ml and greater than 10(7) PFU/ml, respectively. The apparent bloodmeal size of the 2 species differed by 8-fold and suggested that, in terms of the number of PFU ingested, R. appendiculatus was more susceptible than A. variegatum to per os infection by Thogoto virus.

Assessment of Leishmaniasis notification system in Santiago del Estero, Argentina, 1990-1993.

Using a capture-recapture method, this study evaluates the completeness of the cutaneous leishmaniasis (CL) surveillance system in four districts of Santiago del Estero province, Argentina, for the period 1990-1993. Four reporting sources were evaluated: medical records kept by health facilities, interviews conducted during a case-control study, and the national and provincial levels of the leishmaniasis surveillance system (LSS). Using the capture-recapture method it was estimated that 210 cases (95% confidence interval [CI]: 202-218) of CL occurred in the four districts during the study period. Completeness of reporting to the leishmaniasis surveillance system at the national level was estimated to be 44.8% (95% CI: 43.2-46.4). The study results indicate that there is substantial underreporting within the LSS, although it did show the appropriate secular trends. The reasons for under-reporting and methods for addressing this problem are discussed.

Cutaneous leishmaniasis in the Peruvian Andes: risk factors identified from a village cohort study.

Risk factors for cutaneous leishmaniasis were identified from a comparative study of transmission rates in 27 villages in the Departments of Lima, Ancash, and Piura in Peru. To evaluate regression analysis as a tool for the incrimination of sand fly vectors in the absence of other biologic evidence, univariate and multivariate logistic regression analyses were used to identify which of 14 variables (the abundance of nine sand fly species, four social factors, and region) predicted transmission rates in villages (incidence, active prevalence, or cumulative prevalence). In general, suspected or proven vectors (e.g., Lutzomyia peruensis) had the strongest associations with transmission rate, indicating that regression is a useful supplementary method of incriminating vectors. Regression was then used to quantify the importance of suspected risk factors. Transmission rate increased with the abundance of Lu. peruensis, Lu. ayacuchensis, Lu. noguchii, and, to a lesser extent, Lu. verrucarum and transmission was higher among villagers who slept more frequently in temporary shelters in crop areas. There were also weak effects of the number of dogs/ person (negative) and the number of persons/household (positive). Linear regressions failed to detect a threshold sand fly density below which transmission ceases. The minimal adequate multiple regression model explained 82% of the variance in village incidence rates. This model was used to predict the effect on incidence of reducing each of the four suspected vectors in northern and southern Peru. The results indicate that vector control programs in the south should aim at Lu. peruensis, Lu. verrucarum, and Lu. noguchii, but focus on Lu. ayacuchensis in the north.