Species Identification and Resistance Status of Anopheles gambiae s.l. (Diptera: Culicidae) Mosquitoes in Guinea.

Insecticide resistance is one of the primary threats to the recent gains in malaria control. This is especially true in Guinea, where long-lasting insecticidal nets are currently the primary vector control intervention. To better inform the national malaria control program on the current status of insecticide resistance in Guinea, resistance bioassays were conducted, using Anopheles gambiae s.l. Giles, in three sites. Molecular analyses were also done on An. gambiae s.l. to determine the species and find whether the target-site mutations kdr and Ace1R were present. Susceptibility tests revealed resistance to DDT and pyrethroids, although mosquitoes were susceptible to deltamethrin in two of the three sites tested. Mosquitoes were susceptible to bendiocarb, except in Kissidougou, Guinea. The kdr-west mutation was widespread and the frequency was 60% or more in all sites. However, the Ace1R mutation was present in low levels. Insecticide susceptibility should continue to be monitored in Guinea to ensure insecticide-based vector control methods remain effective.

Evaluation of the AtrAedes™ Lure for Collection of Culex quinquefasciatus in Gravid Traps.

The typical attractant used in gravid trapping of Culex quinquefasciatus is an aged infusion of organic materials, which can change in attractiveness over time. A standardized chemical attractant dispenser derived from grass infusion, the AtrAedes™ lure, has been produced for the surveillance of the dengue vector Aedes aegypti. A study using this lure in combination with the Centers for Disease Control and Prevention gravid traps was conducted in Tanga, Tanzania. The addition of the lure to traps baited with either grass infusion or tap water did not result in significant increases in trap catch. Grass infusion-baited traps (with and without the AtrAedes lure) collected significantly more Cx. quinquefasciatus than traps baited with AtrAedes + tap water, tap water alone, or AtrAedes alone. The catches of the traps baited with AtrAedes + tap water, tap water alone, and AtrAedes alone were not significantly different from each other. Although the placement of the lure in the base of the trap may have decreased trap catches, it seems that the AtrAedes is not as effective as grass infusion for collecting Cx. quinquefasciatus in Tanzania.

Implications of radial head hemiarthroplasty dish depth on radiocapitellar contact mechanics.

PURPOSE: To investigate the effect of radial head implant dish depth on radiocapitellar joint contact mechanics. METHODS: Computed tomography images of 13 fresh-frozen cadaveric humeri were reconstructed into 3-dimensional finite element models with accurate cartilage geometry. Native humeri were paired with the corresponding native radial heads and axisymmetric radial head prosthesis models of the following dish depths: 1.0 mm, 1.5 mm, 2.0 mm, 2.5 mm, and 3.0 mm. Radiocapitellar contact mechanics were quantified at 4 different flexion angles (0°, 45°, 90°, and 135°) with a 100-N axial load applied to the radial head using a modeling protocol previously validated by cadaveric studies. The radial head was permitted to translate freely to its optimal position while the humerus was fully constrained. Output variables were contact area and peak contact stress. RESULTS: All prostheses had significantly decreased contact area and increased peak contact stress at all flexion angles relative to the native radiocapitellar joint. Contact area increased with prosthesis dish depth until reaching a plateau with a predicted local maximum at a mean depth of 3.2 ± 0.7 mm. Peak contact stress was elevated for both the shallowest and deepest models and reached a predicted local minimum at a mean depth of 1.8 ± 0.3 mm. CONCLUSIONS: Contact area and peak contact stress were dependent on radial head prosthesis dish depth. There was an optimal implant dish depth for radiocapitellar contact mechanics at approximately 2 mm. CLINICAL RELEVANCE: Optimizing radiocapitellar contact mechanics using rigorous and systematic prosthesis design techniques may lead to better clinical outcomes due to reduced capitellar cartilage degradation.

Preliminary evaluation of a nonanal lure for collection of gravid Culex quinquefasciatus.

Gravid traps are important tools for disease monitoring and for research on mosquito ovipositional behavior. Two experiments were conducted to evaluate a 2% nonanal lure in gravid mosquito traps in Ifakara, Tanzania. The 1st experiment focused on whether water was needed in the pan below the trap for the nonanal lure to be effective. There was no significant difference between the numbers of gravid females of Culex quinquefasciatus collected in traps using a nonanal lure either with or without water. The 2nd experiment compared the lure, without water, to a grass infusion and a blank trap, without water or attractant. Significantly more mosquitoes were collected in traps with grass infusion than in traps with the other attractants, which were not significantly different from each other. Although more mosquitoes were collected in traps with grass infusion, substantial numbers were also collected in traps with the nonanal lure and unbaited traps.

Evaluation of a nonanal-trimethylamine lure for collection of Culex quinquefasciatus (Diptera: Culicidae) in gravid traps.

Gravid traps are useful tools for monitoring vector-borne pathogens in mosquitoes, particularly for those pathogens transmitted by Culex quinquefasciatus Say. One of the primary challenges in the use of gravid traps is the necessity of the inclusion of an oviposition attractant, usually an infusion of organic material, which changes in attractiveness over time. However, a standardized lure, using nonanal and trimethylamine (N + TMA), has been developed and is commercially available. The N + TMA lure was tested against grass infusion and tap water in Tanzania, where Cx. quinquefasciatus is a vector of lymphatic filariasis. Traps baited with grass infusion collected significantly more mosquitoes than N + TMA-baited traps, which collected significantly more than traps baited with tap water. The advantages and disadvantages of the standardized lure are discussed.

Effect of the volume of organic infusion used in gravid traps for collecting Culex quinquefasciatus (Diptera: Culicidae).

Traps that selectively collect gravid mosquitoes have advantages over other collection methods for the purpose of disease surveillance: they trap mosquitoes with a higher probability of carrying disease as they have blood fed on at least one occasion. Gravid traps typically use infusions of organic material to attract gravid mosquitoes, particularly Culex quinquefasciatus (Say). These infusions are heavy and have an unpleasant odor, presenting logistical difficulties for disease monitoring programs. Typically, gravid traps use 4 liters of infusion. The present trial compared the responses of gravid female mosquitoes to 2 and 4 liters of infusion to see if equivalent numbers of mosquitoes could be collected using the smaller volume. In an attempt to better understand the effects of volume of infusion on mosquito oviposition behavior, egg laying on the two volumes was also monitored. There was a significant difference between the mean numbers of egg rafts laid on 2 and 4 liters of infusion. However, the mean numbers of gravid Cu. quinquefasciatus collected in gravid traps with 2 and 4 liters were not significantly different. The results indicate that 2 liters can be used instead of 4 liters for gravid trapping, significantly reducing the cost and logistical difficulties associated with such efforts. The behavioral responses of gravid females to different volumes are also discussed.

Evaluation of indoor residual spraying with the pyrrole insecticide chlorfenapyr against pyrethroid-susceptible Anopheles arabiensis and pyrethroid-resistant Culex quinquefasciatus mosquitoes.

Chlorfenapyr is a pyrrole insecticide with a unique non-neurological mode of action. Laboratory bioassays of chlorfenapyr comparing the mortality of pyrethroid-susceptible and -resistant Anopheles gambiae s.s. and Culex quinquefasciatus mosquitoes indicated that operational cross-resistance is unlikely to occur (resistance ratio ranged between 0 and 2.1). Three trials of chlorfenapyr indoor residual spraying were undertaken in experimental huts in an area of rice irrigation in northern Tanzania that supports breeding of A. arabiensis. Daily mosquito collections were undertaken to assess product performance primarily in terms of mortality. In the second trial, 250mg/m(2) and 500mg/m(2) chlorfenapyr were tested for residual efficacy over 6 months. Both dosages killed 54% of C. quinquefasciatus, whilst for A. arabiensis 250mg/m(2) killed 48% compared with 41% for 500mg/m(2); mortality was as high at the end of the trial as at the beginning. In the third trial, 250mg/m(2) chlorfenapyr was compared with the pyrethroid alpha-cypermethrin dosed at 30mg/m(2). Chlorfenapyr performance was equivalent to the pyrethroid against A. arabiensis, with both insecticides killing 50% of mosquitoes. Chlorfenapyr killed a significantly higher proportion of pyrethroid-resistant C. quinquefasciatus (56%) compared with alpha-cypermethrin (17%). Chlorfenapyr has the potential to be an important addition to the limited arsenal of public health insecticides for indoor residual control of A. arabiensis and pyrethroid-resistant species of mosquito.

Is K-O Tab 1-2-3((R)) long lasting on non-polyester mosquito nets?

Many societies use locally sourced mosquito nets made from a variety of materials. For protecting against malaria these require regular re-treatment with insecticide. K-O Tab 1-2-3 is a 'dip-it-yourself' long-lasting formulation with time-limited interim recommendation from WHO for treatment of washed white and coloured polyester nets for up to 15 washes. To determine wash-resistance on different fabrics, nets made of polyester, polyethylene, cotton or nylon were treated with K-O Tab 1-2-3 and washed up to 20 times using standard WHO washing procedures. Efficacy was assessed using cone and cylinder bioassays and tunnel tests, and deltamethrin content using high-pressure liquid chromatography. Polyethylene and cotton nets treated with K-O Tab 1-2-3 and washed 20 times achieved the WHO threshold of >80% mortality in tunnel tests. Polyethylene matched the performance of polyester in all bioassays in contrast to cotton and nylon which produced low mortality and knock-down in cone and cylinder bioassays. After 20 washes 16.5% of the loading dose of deltamethrin remained on the polyester nets compared with 28.7% on polyethylene, 38.9% on cotton and 2.2% on nylon. Cotton nets retained a high concentration of insecticide but the relatively poor performance in terms of knock-down and mortality suggest most insecticide is bound within the cotton fibres rather than on the surface. K-O Tab 1-2-3 renders insecticide wash fast on polyethylene nets, less so on cotton and nylon. Nets made from polyethylene can be treated in the home to render the insecticide long lasting.

Loss of protection with insecticide-treated nets against pyrethroid-resistant Culex quinquefasciatus mosquitoes once nets become holed: an experimental hut study.

BACKGROUND: An important advantage of pyrethroid-treated nets over untreated nets is that once nets become worn or holed a pyrethroid treatment will normally restore protection. The capacity of pyrethroids to kill or irritate any mosquito that comes into contact with the net and prevent penetration of holes or feeding through the sides are the main reasons why treated nets continue to provide protection despite their condition deteriorating over time. Pyrethroid resistance is a growing problem among Anopheline and Culicine mosquitoes in many parts of Africa. When mosquitoes become resistant the capacity of treated nets to provide protection might be diminished, particularly when holed. An experimental hut trial against pyrethroid-resistant Culex quinquefasciatus was therefore undertaken in southern Benin using a series of intact and holed nets, both untreated and treated, to assess any loss of protection as nets deteriorate with use and time. RESULTS: There was loss of protection when untreated nets became holed; the proportion of mosquitoes blood feeding increased from 36.2% when nets were intact to between 59.7% and 68.5% when nets were holed to differing extents. The proportion of mosquitoes blood feeding when treated nets were intact was 29.4% which increased to 43.6-57.4% when nets were holed. The greater the number of holes the greater the loss of protection regardless of whether nets were untreated or treated. Mosquito mortality in huts with untreated nets was 12.9-13.6%; treatment induced mortality was less than 12%. The exiting rate of mosquitoes into the verandas was higher in huts with intact nets. CONCLUSION: As nets deteriorate with use and become increasingly holed the capacity of pyrethroid treatments to restore protection is greatly diminished against resistant Culex quinquefasciatus mosquitoes.

Reliability of water volumetry and the figure of eight method on subjects with ankle joint swelling.

STUDY DESIGN: Single-group repeated measures with 2 raters. OBJECTIVES: To determine the interrater and intrarater reliability of water volumetry and the figure of eight method on subjects with ankle joint swelling. BACKGROUND: Measurements of ankle swelling are commonly performed to determine the nature and stage of injury and to monitor progress made during rehabilitation. Water volumetry and the figure of eight method are 2 techniques used to measure ankle swelling. METHODS AND MEASURES: Twenty-nine subjects with ankle swelling were measured by 2 raters with the hypothesis that both measurement techniques would be reliable. Each rater performed 3 measurements of the swollen ankle using both measurement techniques during a single test session. The order of the rater and of the measurement technique was randomized, and the raters were blinded to each other's measurements. RESULTS: We found high interrater reliability for both the water volumetry (ICC [intraclass correlation coefficient] = 0.99) and figure of eight methods (ICC = 0.98). Additionally, intrarater reliability was high for both raters using both methods (ICCs = 0.98-0.99). CONCLUSIONS: Both methods are reliable measures of ankle swelling. The authors recommend the figure of eight method because of its ease of use, time efficiency, and cost effectiveness. However, water volumetry may be more appropriate when measuring diffuse lower-extremity swelling. Reliability of these 2 methods was established using subjects with foot or ankle pathology. Therefore, the results are applicable and generalizable to the clinical setting.

Preoperative regimens of magnesium facilitate recovery of function and prevent subcortical atrophy following lesions of the rat sensorimotor cortex.

Following brain injury, there is a reduction of intra- and extracellular levels of magnesium (Mg++), which may contribute to the severity of the lesion-induced behavioral impairments. Injections of magnesium prior to or after brain injury attenuate these behavioral impairments. The present study extends these findings by manipulating the number of injections and the time period between the injections and the time of injury. Rats were given either two or five daily preoperative injections of MgCl2 (1 mmol/kg, i.p.), or saline (1 ml/kg, i.p.) with the final injection given 24 h prior to electrolytic lesions of the somatic sensorimotor cortex (SMC). Following SMC lesions the rats exhibited contralateral deficits in forelimb placing and locomotor placing. Rats treated with either two or five preoperative injections of MgCl2 showed a reduction in the initial magnitude of the contralateral deficits and an accelerated rate of recovery compared to saline-treated rats. In addition, analysis of striatal atrophy revealed that MgCl2 treatment prevented atrophy in the ipsilateral posterior striatum compared to rats treated with saline. These data suggest that preoperative injections of MgCl2 produce facilitation of sensorimotor recovery and reduce subcortical atrophy. Moreover, to observe the beneficial effects of MgCl2, the timing of injections need not be tied to the period immediately around the brain injury. The present data may indicate that daily supplements of magnesium may partially protect against some of the deleterious effects of brain injury.