Young transgender women (YTGW) who sell or trade sex have among the highest HIV incidence rates in Thailand. Using qualitative methods, we assessed perceived acceptability, feasibility, and optimal design of a combination HIV prevention intervention including PrEP for YTGW. Key informant interviews were conducted during July 2016-July 2018 with 21 YTGW, aged 18-26 years, who sold sex and resided in Bangkok or Pattaya, Thailand. Grounded theory and content analysis were used for data analysis. Most YTGW interviewed reported high interest in HIV prevention research and believed participation in it supported sexual health. However, participants perceived HIV studies as complicated and time-consuming. Regarding PrEP, participants suggested more PrEP options beyond daily oral PrEP and expressed concerns related to perceived side effects of PrEP, including interaction with gender-affirming hormone therapy. Improving PrEP knowledge, being able to self-assess HIV risk, and reducing HIV/PrEP stigma could increase interest in research and PrEP uptake among YTGW.

BACKGROUND: Daily oral pre-exposure prophylaxis (PrEP) is effective in preventing HIV infection, but no study has evaluated combination prevention interventions with PrEP for transgender women (TGW) and men who have sex with men (MSM) who sell sex. METHODS: The Combination Prevention Effectiveness (COPE) study was a community-based, non-randomized implementation study in Bangkok and Pattaya, Thailand. Participants were HIV-negative MSM and TGW aged 18-26 years who reported exchanging sex with men in the prior 12 months and who met 2014 U.S. Public Health Service PrEP eligibility criteria. The intervention included quarterly HIV testing, semiannual testing for sexually transmitted infections, provision of condoms with lubricant, and the opportunity to initiate or end daily oral PrEP use at any time during study participation. Participants taking PrEP received monthly adherence counseling and short message service reminders. The primary outcome was HIV incidence rate ratio (IRR) on PrEP vs. not on PrEP. Secondary outcomes were PrEP initiation, PrEP use at 12 months, and PrEP adherence. FINDINGS: From October 2017 to August 2019, 846 participants were enrolled: 531 (62.8%) immediately initiated PrEP; 104 (12.3%) subsequently initiated PrEP, and 211 (24.9%) never initiated PrEP. Among those initiating PrEP within 30 days of enrollment; 85.9% were on PrEP at the 12-months. When taking PrEP, participants reported adherent PrEP use at 94.2% of quarterly assessments. Ten HIV seroconversions occurred without PrEP use (incidence rate [IR] = 3.42 per 100 person-years [PY]; 95% CI = 1.64-6.30), while zero cases occurred with PrEP use (IR = 0.0 per 100PY; 95% CI = 0.0-0.62), with IRR = 0.0 (95% CI = 0.0-0.22; p < 0.001). INTERPRETATION: Young Thai MSM and TGW who exchange sex can have high PrEP uptake, persistence and adherence, and low HIV incidence when offered in supportive community-based settings. FUNDING: U.S. National Institute of Allergy and Infectious Diseases; Centers for Disease Control and Prevention.

Pharmaceutical industry-led access programs are growing in number globally and are increasingly adopting a hybrid approach intended to generate commercial and social value in parallel. We developed and applied a new conceptual framework in a descriptive analysis of observable indicators measuring commercial and social value for 91 programs registered in the Access Observatory. We found that most programs had features consistent with the generation of commercial value, directly through revenue generation (50.0%), or indirectly by creating competitive advantage (70.3%). We also found that most programs were implemented in countries where the company has commercial products registered (85.5%). While many programs had features consistent with the generation of social value, it was difficult to ascertain the level of that value because most did not share data (83.5%) and had not been evaluated (74.7%). Future efforts by the global health community and the pharmaceutical industry should focus on strengthening measurement and reporting on commercial and social indicators of industry-led access programs.

HIV incidence is high and persistent among cisgender men who have sex with men (MSM) and transgender women (TGW) who have sex with men, particularly among those who sell or trade sex. In preparation for an open-label combination HIV pre-exposure prophylaxis (PrEP) program for these groups, we conducted formative research to explore the context of sex work/trade and factors that affect implementation of PrEP interventions. This study analyzed interviews with 20 young (aged 18-26 years) MSM and TGW who sell/trade sex and three sex work venue managers in Bangkok and Pattaya, Thailand. Participants described diverse contexts of sex work/trade, including in multiple informal and formal sex venues. Several participants reported mobility across provinces and out of the country, which led to intermittent sex work/trade. TGW sex workers reported challenges with access and cost of femininizing hormones and limited employment opportunities. Factors that could facilitate or challenge PrEP program implementation included HIV stigma, the role of venue management in sexual health practice, lack of PrEP knowledge, lower perceived HIV risk, and interest in personal health and wellbeing. Program implementers must consider myriad factors to successfully implement PrEP among young MSM and TGW engaged in sex work or trade in Thailand.

PURPOSE: To examine how recent sex work is identified and the HIV risk factors and service needs among Thai cisgender men who have sex with men (MSM) and transgender women (TGW) who exchange sex. METHODS: MSM and TGW in Bangkok and Pattaya who exchanged sex in the last year (n= 890) were recruited through social media, outreach, and word-of-mouth. Recent sex exchange was based on the primary question, "in the last 30 days, have you sold or traded sex"; secondary questions (regarding income source and client encounters) were also investigated. RESULTS: Overall, 436 (48%) participants engaged in sex work in the last 30 days; among those, 270 (62%) reported exchanging sex by the primary question, and 160 (37%) based on secondary questions only. Recent sex exchange was associated with gonorrhea, syphilis, discussing PrEP with others, and using condoms, alcohol, methamphetamine, amyl nitrate, and Viagra®. Exchanging sex based on secondary questions only was associated with being in a relationship, social media recruitment, less recent anal intercourse, and not discussing PrEP. CONCLUSIONS: Thai MSM and TGW who exchange sex need regular access to HIV/STI prevention, testing, and treatment services, and multiple approaches to assessing sex work will help identify and serve this diverse and dynamic population.

BACKGROUND: Epidemiologic research among migrant populations is limited by logistical, methodological, and ethical challenges, but it is necessary for informing public health and humanitarian programming. OBJECTIVE: We describe a methodology to estimate HIV prevalence among Venezuelan migrants in Colombia. METHODS: Respondent-driven sampling, a nonprobability sampling method, was selected for attributes of reaching highly networked populations without sampling frames and analytic methods that permit estimation of population parameters. Respondent-driven sampling was modified to permit electronic referral of peers via SMS text messaging and WhatsApp. Participants complete sociobehavioral surveys and rapid HIV and syphilis screening tests with confirmatory testing. HIV treatment is not available for migrants who have entered Colombia through irregular pathways; thus, medicolegal services integrated into posttest counseling provide staff lawyers and legal assistance to participants diagnosed with HIV or syphilis for sustained access to treatment through the national health system. Case finding is integrated into respondent-driven sampling to allow partner referral. This study is implemented by a local community-based organization providing HIV support services and related legal services for Venezuelans in Colombia. RESULTS: Data collection was launched in 4 cities in July and August 2021. As of November 2021, 3105 of the target 6100 participants were enrolled, with enrollment expected to end by February/March 2022. CONCLUSIONS: Tailored methods that combine community-led efforts with innovations in sampling and linkage to care can aid in advancing health research for migrant and displaced populations. Worldwide trends in displacement and migration underscore the value of improved methods for translation to humanitarian and public health programming. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): DERR1-10.2196/36026.

BACKGROUND: Long-lasting insecticidal nets (LLINs) are the primary malaria prevention and control intervention in many parts of sub-Saharan Africa. While LLINs are expected to last at least 3 years under normal use conditions, they can lose effectiveness because they fall out of use, are discarded, repurposed, physically damaged, or lose insecticidal activity. The contributions of these different interrelated factors to durability of nets and their protection against malaria have been unclear. METHODS: Starting in 2009, LLIN durability studies were conducted in seven countries in Africa over 5 years. WHO-recommended measures of attrition, LLIN use, insecticidal activity, and physical integrity were recorded for eight different net brands. These data were combined with analyses of experimental hut data on feeding inhibition and killing effects of LLINs on both susceptible and pyrethroid resistant malaria vectors to estimate the protection against malaria transmission-in terms of vectorial capacity (VC)-provided by each net cohort over time. Impact on VC was then compared in hypothetical scenarios where one durability outcome measure was set at the best possible level while keeping the others at the observed levels. RESULTS: There was more variability in decay of protection over time by country than by net brand for three measures of durability (ratios of variance components 4.6, 4.4, and 1.8 times for LLIN survival, use, and integrity, respectively). In some countries, LLIN attrition was slow, but use declined rapidly. Non-use of LLINs generally had more effect on LLIN impact on VC than did attrition, hole formation, or insecticide loss. CONCLUSIONS: There is much more variation in LLIN durability among countries than among net brands. Low levels of use may have a larger impact on effectiveness than does variation in attrition or LLIN degradation. The estimated entomological effects of chemical decay are relatively small, with physical decay probably more important as a driver of attrition and non-use than as a direct cause of loss of effect. Efforts to maximize LLIN impact in operational settings should focus on increasing LLIN usage, including through improvements in LLIN physical integrity. Further research is needed to understand household decisions related to LLIN use, including the influence of net durability and the presence of other nets in the household.

BACKGROUND: Pre-exposure prophylaxis (PrEP) is highly effective in the prevention of HIV acquisition, particularly for men who have sex with men (MSM). Questions remain on the benefits of PrEP and implementation strategies for those at occupational risk of HIV acquisition in sex work, as well as on methods to support adherence among young people who initiate PrEP. OBJECTIVE: The Combination Prevention Effectiveness study for young cisgender MSM and transgender women (TGW) aims to assess the effectiveness and cost-effectiveness of a combination intervention among HIV-uninfected young MSM and TGW engaged in sex work in Thailand. METHODS: This open-label, nonrandomized assessment compares the relative effectiveness of a combination prevention intervention with and without daily oral emtricitabine and tenofovir disoproxil fumarate (Truvada) PrEP with SMS-based adherence support. HIV-uninfected young MSM and TGW aged 18 to 26 years in Bangkok and Pattaya who self-report selling/exchanging sex at least once in the previous 12 months are recruited by convenience sampling and peer referral and are eligible regardless of their intent to initiate PrEP. At baseline, participants complete a standard assessment for PrEP eligibility and may initiate PrEP then or at any time during study participation. All participants complete a survey and HIV testing at baseline and every 3 months. Participants who initiate PrEP complete monthly pill pickups and may opt-in to SMS reminders. All participants are sent brief weekly SMS surveys to assess behavior with additional adherence questions for those who initiated PrEP. Adherence is defined as use of 4 or more pills within the last 7 days. The analytic plan uses a person-time approach to assess HIV incidence, comparing participant time on oral PrEP to participant time off oral PrEP for 12 to 24 months of follow-up, using a propensity score to control for confounders. Enrollment is based on the goal of observing 620 person-years (PY) on PrEP and 620 PY off PrEP. RESULTS: As of February 2019, 445 participants (417 MSM and 28 TGW) have contributed approximately 168 PY with 95% (73/77) retention at 12 months. 74.2% (330/445) of enrolled participants initiated PrEP at baseline, contributing to 134 PY of PrEP adherence, 1 PY nonadherence, and 33 PY PrEP nonuse/noninitiation. Some social harms, predominantly related to unintentional participant disclosure of PrEP use and peer stigmatization of PrEP and HIV, have been identified. CONCLUSIONS: The majority of cisgender MSM and TGW who exchange sex and participate in this study are interested in PrEP, report taking sufficient PrEP, and stay on PrEP, though additional efforts are needed to address community misinformation and stigma. This novel multilevel, open-label study design and person-time approach will allow evaluation of the effectiveness and cost-effectiveness of combination prevention intervention in the contexts of both organized sex work and exchanged sex. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): RR1-10.2196/15354.

BACKGROUND: In this semi-field study, a new polymer-enhanced deltamethrin formulation, K-Othrine((R)) PolyZone, was compared to a standard deltamethrin product for residual activity against a susceptible strain of laboratory-reared Anopheles gambiae using standard WHO cone bioassays. METHODS: Residual insecticide efficacy was recorded after exposure to metal, cement and wood panels maintained in experimental huts in sub-tropical environmental conditions in north central Florida, USA, and panels stored in a climate controlled chamber located at the Centers for Disease Control and Prevention, Georgia, USA. CONCLUSIONS: K-Othrine((R)) PolyZone demonstrated 100% control on metal and cement panels 1 year post application and > 80% control on wood panels up to 6 mo. The new formulation should be considered for use in indoor residual spray programmes requiring long-term control of malaria vectors.

BACKGROUND: Indoor residual spraying (IRS) and long-lasting insecticidal nets (LLINs) remain the cornerstones of malaria vector control. However, the development of insecticide resistance and its implications for operational failure of preventative strategies are of concern. The aim of this study was to characterize insecticide resistance among Anopheles arabiensis populations in Ethiopia and describe temporal and spatial patterns of resistance between 2012 and 2016. METHODS: Between 2012 and 2016, resistance status of An. arabiensis was assessed annually during the long rainy seasons in study sites from seven of the nine regions in Ethiopia. Insecticide resistance levels were measured with WHO susceptibility tests and CDC bottle bioassays using insecticides from four chemical classes (organochlorines, pyrethroids, organophosphates and carbamates), with minor variations in insecticides tested and assays conducted between years. In selected sites, CDC synergist assays were performed by pre-exposing mosquitoes to piperonyl butoxide (PBO). In 2015 and 2016, mosquitoes from DDT and deltamethrin bioassays were randomly selected, identified to species-level and screened for knockdown resistance (kdr) by PCR. RESULTS: Intense resistance to DDT and pyrethroids was pervasive across Ethiopia, consistent with historic use of DDT for IRS and concomitant increases in insecticide-treated net coverage over the last 15 years. Longitudinal resistance trends to malathion, bendiocarb, propoxur and pirimiphos-methyl corresponded to shifts in the national insecticide policy. By 2016, resistance to the latter two insecticides had emerged, with the potential to jeopardize future long-term effectiveness of vector control activities in these areas. Between 2015 and 2016, the West African (L1014F) kdr allele was detected in 74.1% (n = 686/926) of specimens, with frequencies ranging from 31 to 100% and 33 to 100% in survivors from DDT and deltamethrin bioassays, respectively. Restoration of mosquito susceptibility, following pre-exposure to PBO, along with a lack of association between kdr allele frequency and An. arabiensis mortality rate, both indicate metabolic and target-site mutation mechanisms are contributing to insecticide resistance. CONCLUSIONS: Data generated by this study will strengthen the National Malaria Control Programme's insecticide resistance management strategy to safeguard continued efficacy of IRS and other malaria control methods in Ethiopia.

BACKGROUND: In recent years, there has been growing awareness of the significant burden of Chagas disease in the United States (US). However, epidemiological data on both prevalence and access to care for this disease are limited. The objective of this study is to provide an updated national estimate of Chagas disease prevalence, the first state-level estimates of cases of T. cruzi infection in the US and to analyze these estimates in the context of data on confirmed cases of infection in the US blood supply. METHODS: In this study, we calculated estimates of the state and national prevalence of Chagas disease. The number of residents originally from Chagas disease endemic countries were computed using data on Foreign-Born Hispanic populations from the American Community Survey, along with recent prevalence estimates for Chagas disease in Latin America from the World Health Organization that were published in 2006 and updated in 2015. We then describe the distribution of estimated cases in each state in relation to the number of infections identified in the donated blood supply per data from the AABB (formerly American Association of Blood Banks). FINDINGS: The results of this analysis offer an updated national estimate of 238,091 cases of T. cruzi infection in the United States as of 2012, using the same method as was used by Bern and Montgomery to estimate cases in 2005. This estimate indicates that there are 62,070 cases less than the most recent prior estimate, though it does not include undocumented immigrants who may account for as many as 109,000 additional cases. The state level results show that four states (California, Texas, Florida and New York) have over 10,000 cases and an additional seven states have over 5,000 cases. Moreover, since 2007, the AABB has reported 1,908 confirmed cases of T. cruzi infection identified through screening of blood donations. CONCLUSIONS: This study demonstrates a substantial burden of Chagas disease in the US, with state variation that reflects the distribution of at risk Latin American immigrant populations. The study lends important new insight into the distribution of this disease in the US and highlights the need for further research quantifying prevalence and incidence to guide interventions for control of Chagas disease across the US.

Estimating the age distribution of mosquito populations is crucial for assessing their capacity to transmit disease and for evaluating the efficacy of available vector control programs. This study reports on the capacity of the near-infrared spectroscopy (NIRS) technique to rapidly predict the ages of the principal dengue and Zika vector, Aedes aegypti. The age of wild-type males and females, and males and females infected with wMel and wMelPop strains of Wolbachia pipientis were characterized using this method. Calibrations were developed using spectra collected from their heads and thoraces using partial least squares (PLS) regression. A highly significant correlation was found between the true and predicted ages of mosquitoes. The coefficients of determination for wild-type females and males across all age groups were R2 = 0.84 and 0.78, respectively. The coefficients of determination for the age of wMel and wMelPop infected females were 0.71 and 0.80, respectively (P< 0.001 in both instances). The age of wild-type female Ae. aegypti could be identified as < or ≥ 8 days old with an accuracy of 91% (N = 501), whereas female Ae. aegypti infected with wMel and wMelPop were differentiated into the two age groups with an accuracy of 83% (N = 284) and 78% (N = 229), respectively. Our results also indicate NIRS can distinguish between young and old male wild-type, wMel and wMelPop infected Ae. aegypti with accuracies of 87% (N = 253), 83% (N = 277) and 78% (N = 234), respectively. We have demonstrated the potential of NIRS as a predictor of the age of female and male wild-type and Wolbachia infected Ae. aegypti mosquitoes under laboratory conditions. After field validation, the tool has the potential to offer a cheap and rapid alternative for surveillance of dengue and Zika vector control programs.

The release of Wolbachia infected mosquitoes is likely to form a key component of disease control strategies in the near future. We investigated the potential of using near-infrared spectroscopy (NIRS) to simultaneously detect and identify two strains of Wolbachia pipientis (wMelPop and wMel) in male and female laboratory-reared Aedes aegypti mosquitoes. Our aim is to find faster, cheaper alternatives for monitoring those releases than the molecular diagnostic techniques that are currently in use. Our findings indicate that NIRS can differentiate females and males infected with wMelPop from uninfected wild type samples with an accuracy of 96% (N = 299) and 87.5% (N = 377), respectively. Similarly, females and males infected with wMel were differentiated from uninfected wild type samples with accuracies of 92% (N = 352) and 89% (N = 444). NIRS could differentiate wMelPop and wMel transinfected females with an accuracy of 96.6% (N = 442) and males with an accuracy of 84.5% (N = 443). This non-destructive technique is faster than the standard polymerase chain reaction diagnostic techniques. After the purchase of a NIRS spectrometer, the technique requires little sample processing and does not consume any reagents.

BACKGROUND: With the emergence and spread of vector resistance to pyrethroids and DDT in Africa, several countries have recently switched or are considering switching to carbamates and/or organophosphates for indoor residual spraying (IRS). However, data collected on the residual life of bendiocarb used for IRS in some areas indicate shorter than expected bio-efficacy. This study evaluated the effect of pH and wall type on the residual life of the carbamates bendiocarb and propoxur as measured by the standard World Health Organization (WHO) cone bioassay test. METHODS: In phase I of this study, bendiocarb and propoxur were mixed with buffered low pH (pH 4.3) local water and non-buffered high pH (pH 8.0) local water and sprayed on two types of wall surface, mud and dung, in experimental huts. In the six month phase II study, the two insecticides were mixed with high pH local water and sprayed on four different surfaces: painted, dung, mud and mud pre-wetted with water. The residual bio-efficacy of the insecticides was assessed monthly using standard WHO cone bioassay tests. RESULTS: In phase I, bendiocarb mixed with high pH water killed more than 80 % of susceptible Anopheles arabiensis mosquitoes for two months on both dung and mud surfaces. On dung surfaces, the 80 % mortality threshold was achieved for three months when the bendiocarb was mixed with low pH water and four months when it was mixed with high pH water. Propoxur lasted longer than bendiocarb on dung surfaces, staying above the 80 % mortality threshold for four and five months when mixed with high and low pH water, respectively. Phase II results also showed that the type of surface sprayed has a significant impact on the bio-efficacy of bendiocarb. Keeping the spray water constant at the same high pH of 8.0, bendiocarb killed 100 % of exposed mosquitoes on impervious painted surfaces for the six months of the study period compared with less than one month on mud surfaces. CONCLUSIONS: Mixing the insecticides in alkaline water did not reduce the residual bio-efficacy of bendiocarb. However, bendiocarb performed much better on impervious (painted) surfaces than on porous dung or mud ones. Propoxur was less affected by wall type than was bendiocarb. Studies on the interaction between wall materials, soil, humidity, temperature and pH and the residual bio-efficacy of new and existing insecticides are recommended prior to their wide use in IRS.

Arthropod vectors transmit organisms that cause many emerging and reemerging diseases, and their control is reliant mainly on the use of chemical insecticides. Only a few classes of insecticides are available for public health use, and the increased spread of insecticide resistance is a major threat to sustainable disease control. The primary strategy for mitigating the detrimental effects of insecticide resistance is the development of an insecticide resistance management plan. However, few examples exist to show how to implement such plans programmatically. We describe the formulation and implementation of a resistance management plan for mosquito vectors of human disease in Zambia. We also discuss challenges, steps taken to address the challenges, and directions for the future.

BACKGROUND: A key goal of malaria control is to achieve universal access to, and use of, long-lasting insecticidal nets (LLINs) among people at risk for malaria. Quantifying the number of LLINs needed to achieve and maintain universal coverage requires knowing when nets need replacement. Longitudinal studies have observed physical deterioration in LLINs well before the assumed net lifespan of 3 years. The objective of this study was to describe attrition, physical integrity and insecticide persistence of LLINs over time to assist with better quantification of nets needing replacement. METHODS: 999 LLINs distributed in 2011 in two highly endemic provinces in Zambia were randomly selected, and were enrolled at 12 months old. LLINs were followed every 6 months up to 30 months of age. Holes were counted and measured (finger, fist, and head method) and a proportional hole index (pHI) was calculated. Households were surveyed about net care and repair and if applicable, reasons for attrition. Functional survival was defined as nets with a pHI <643 and present for follow-up. At 12 and 24 months of age, 74 LLINs were randomly selected for examination of insecticidal activity and content using bioassay and chemical analysis methods previously described by the World Health Organization (WHO). RESULTS: A total of 999 LLINs were enrolled; 505 deltamethrin-treated polyester nets and 494 permethrin-treated polyethylene nets. With 74 used to examine insecticide activity, 925 were available for full follow-up. At 30 months, 325 (33 %) LLINs remained. Net attrition was primarily due to disposal (29 %). Presence of repairs and use over a reed mat were significantly associated with larger pHIs. By 30 months, only 56 % of remaining nets met criteria for functional survival. A shorter functional survival was associated with having been washed. At 24 months, nets had reduced insecticidal activity (57 % met WHO minimal criteria) and content (5 % met WHO target insecticide content). CONCLUSIONS: The median functional survival time for LLINs observed the study was 2.5-3 years and insecticide activity and content were markedly decreased by 2 years. A better measure of net survival incorporating insecticidal field effectiveness, net physical integrity, and attrition is needed.

Emerging and re-emerging vector-borne diseases such as chikungunya and dengue and associated Aedes vectors are expanding their historical ranges; thus, there is a need for the development of novel insecticides for use in vector control programs. The mosquito toxicity of a novel insecticide and repellent consisting of medium-chain carbon fatty acids (C8910) was examined. Determination of LC50 and LC90 was made against colony-reared Aedes aegypti (L.) and Aedes albopictus (Skuse) using probit analysis on mortality data generated by Centers for Disease Control and Prevention bottle bioassays. Six different concentrations of C8910 + silicone oil yielded an LC50 of 160.3 microg a.i/bottle (147.6-182.7) and LC90 of 282.8 (233.2-394.2) in Ae. aegypti; five concentrations yielded an LC50 of 125.4 (116.1-137.6) and LC90 of 192.5 (165.0-278.9) in Ae. albopictus. Further development of C8910 and similar compounds could provide vector control specialists novel insecticides for controlling insect disease vectors.

Traditional sources of carbon dioxide (CO2), dry ice, and compressed gas, were tested against 3 combinations of food-grade reagents known to generate CO2 using a compact, lightweight generator delivery system with Centers for Disease Control and Prevention light traps. Three 6 x 6 Latin square trials were completed near the Florida Gulf Coast in the Lower Suwannee Wildlife Refuge during the summer of 2013, collecting a total of 31,632 female mosquitoes. Treatments included dry ice, compressed CO2 gas, a control trap (no CO2), citric acid + sodium bicarbonate, vinegar + sodium bicarbonate, and yeast + sugar. Decreasing order of trap collections (treatment mean number of mosquitoes per trap night +/- standard error) were dry ice 773.5 (+/-110.1) > compressed gas 440.7 (+/-42.3) > citric acid + sodium bicarbonate 197.6 (+/-30.4), yeast + sugar 153.6 (+/-27.4) > vinegar + sodium bicarbonate 109.6 (+/-16.2) > control 82.4 (+/-14.0). A 2-way Kruskal-Wallis analysis by treatment, site, and treatment x site interaction identified significant differences between all treatments. Although dry ice and compressed CO2 gas collected significantly more mosquitoes than other combinations (P < 0.05), use of citric acid and sodium bicarbonate or yeast and sugar greatly outperformed unbaited traps and offer a good alternative to dry ice and compressed gas in areas where these agents are not readily available or are difficult to obtain due to logistical constraints. An inexpensive, portable CO2 generator for use with food-grade reagents is described.

BACKGROUND: Long-lasting insecticidal nets (LLINs) are a mainstay of malaria prevention in Africa. More LLINs are available now than in any time previously due to increases in funding for malaria control. LLINs are expected to last three to five years before they need to be replaced. Reports of nets lasting less than three years are frequent in Zambia, which, if true, will increase the number of LLINs needed to maintain universal coverage. METHODS: This study collected nets distributed during mass distribution campaigns. One net was collected from each participating home in 12 districts in 2010 and all nets were examined for holes. One household member was surveyed about net use and care. RESULTS: The study collected 713 polyester nets with a median age of 31 months (range 27-44 months, interquartile (IQR) range: 29-36 months), median number of holes was 17 (IQR: 5-33), and median total hole size was 88.3 sq cm (IQR: 14.5-360.4). The median total number of holes did differ by age of the net, from 27-44 months, but not in a linear fashion. The difference in the number of holes in the newest and oldest nets was not statistically significant. The mean deltamethrin level for all nets was 23 mg/sq m (≥8 mg/sq m is considered effective). There was a larger total hole area in the lower half of the nets (repeat measures ANOVA, F = 228.43, df = 2, p < 0.0001) compared to the upper half and roof of the net. Only 8.7 % of nets had evidence of repairs. CONCLUSIONS: At 27 - 30 months, LLINs already had a large total hole surface area that was equivalent to the oldest nets observed. Nets were often tucked under reed mats which may explain the finding that the largest hole area was found in the lower half of the net. Studies need to be conducted prospectively to determine when physical deterioration occurs and why nets are discarded. Re-enforcing the lower half of the sides of LLINs may help decrease holes.

Interventions targeting adult mosquitoes are used to combat transmission of vector-borne diseases, including dengue. Without available vaccines, targeting the primary vector, Aedes aegypti, is essential to prevent transmission. Older mosquitoes (≥ 7 days) are of greatest epidemiological significance due to the 7-day extrinsic incubation period of the virus. Age-grading of female mosquitoes is necessary to identify post-intervention changes in mosquito population age structure. We developed models using near-infrared spectroscopy (NIRS) to age-grade adult female Ae. aegypti. To determine if diet affects the ability of NIRS models to predict age, two identical larval groups were fed either fish food or infant cereal. Adult females were separated and fed sugar water +/- blood, resulting in four experimental groups. Females were killed 1, 4, 7, 10, 13, or 16 days postemergence. The head/thorax of each mosquito was scanned using a near-infrared spectrometer. Scans from each group were analyzed, and multiple models were developed using partial least squares regression. The best model included all experimental groups, and positively predicted the age group (< or ≥ 7 days) of 90.2% mosquitoes. These results suggest both larval and adult diets can affect the ability of NIRS models to accurately assign age categories to female Ae. aegypti.

Sprayer comparisons and larval morality assays were conducted following SR450 backpack mist blower and Superhawk XP thermal fogger applications of VectobacReg. WDG Bacillus thuringiensis israelensis (Bti) against Culex quinquefasciatus. Bacillus thuringiensis israelensis was applied at maximum label rate in a 232.26-m2 field plot located in north-central Florida with containers placed at 2 heights (ground level and 1.52 m above ground) on stakes positioned 3.04, 6.09, 9.14, 12.19, and 15.24 m from the spray line. Results indicated that there was no significant (P>0.05) difference in 24- and 48-h larval mortality between the 2 sprayers or between the 2 heights. There was significant difference (P<0.05) among the 5 rows, with mortality continuously decreasing with increasing distance from sprayer. Both sprayers provided on average >70% larval mortality 3.04-9.14 m from the spray line, and <60% mortality at 12.19 and 15.24 m. The data suggest that the SR450 and Superhawk XP may be comparable sprayers for use with Bti to control mosquito larvae.

BACKGROUND: Injecting drug use is the primary mode of HIV transmission and acquisition in Afghanistan. People who inject drugs (PWID) in the country have been characterized by high risk injecting behavior and a high burden of HCV infection. We aimed to estimate the burden of HIV, HCV, and other infectious diseases and to identify the correlates of HIV and HCV infection among PWID living in three major Afghan cities in 2009. METHODS: Epidemiologic data was collected among PWID for the integrated biological and behavioral surveillance (IBBS) survey between May and August, 2009 in three Afghan cities. Data were collected using a structured questionnaire and biologic specimens to screen for HIV, HBV, HCV, syphilis, and HSV-2 using rapid testing kits. Multiple logistic regression models were constructed to identify correlates of infection. RESULTS: Among 548 participants, pooled HIV prevalence was 7.1% (Mazar-i-Sharif: 1.0%, Kabul: 3.1%, Herat: 18.4%) and HCV prevalence was 40.3%. Almost all participants with HIV infection were co-infected with HCV (94.9%). Pooled prevalence estimates for other diseases included 7.1% for HBV, 5.5% for syphilis; and 9.3% for HSV-2. Living in Herat, ever in prison and time injecting were independently associated with HIV infection. Living in Kabul, Herat and time injecting were independently associated with HCV infection. CONCLUSIONS: There is a high and heterogeneous burden of HIV and HCV among PWID in Afghan cities. Provision of comprehensive harm reduction services to PWID in Afghanistan is warranted to reduce exposures associated with HIV and HCV infection, especially in the city of Herat.

BACKGROUND: Mosquito age and species identification is a crucial determinant of the efficacy of vector control programmes. Near-infrared spectroscopy (NIRS) has previously been applied successfully to rapidly, non-destructively, and simultaneously determine the age and species of freshly anesthetized African malaria vectors from the Anopheles gambiae s.l. species complex: An. gambiae s. s. and Anopheles arabiensis. However, this has only been achieved on freshly-collected specimens and future applications will require samples to be preserved between field collections and scanning by NIRS. In this study, a sample preservation method (RNAlater(R)) was evaluated for mosquito age and species identification by NIRS against scans of fresh samples. METHODS: Two strains of An. gambiae s.s. (CDC and G3) and two strains of An. arabiensis (Dongola, KGB) were reared in the laboratory while the third strain of An. arabiensis (Ifakara) was reared in a semi-field system. All mosquitoes were scanned when fresh and rescanned after preservation in RNAlater(R) for several weeks. Age and species identification was determined using a cross-validation. RESULTS: The mean accuracy obtained for predicting the age of young (<7 days) or old (≥ 7 days) of all fresh (n = 633) and all preserved (n = 691) mosquito samples using the cross-validation technique was 83% and 90%, respectively. For species identification, accuracies were 82% for fresh against 80% for RNAlater(R) preserved. For both analyses, preserving mosquitoes in RNAlater(R) was associated with a highly significant reduction in the likelihood of a misclassification of mosquitoes as young or old using NIRS. Important to note is that the costs for preserving mosquito specimens with RNAlater(R) ranges from 3-13 cents per insect depending on the size of the tube used and the number of specimens pooled in one tube. CONCLUSION: RNAlater(R) can be used to preserve mosquitoes for subsequent scanning and analysis by NIRS to determine their age and species with minimal costs and with accuracy similar to that achieved from fresh insects. Cold storage availability allows samples to be stored longer than a week after field collection. Further study to develop robust calibrations applicable to other strains from diverse ecological settings is recommended.

Near-infrared spectroscopy (NIRS) was recently applied to age-grade and differentiate laboratory reared Anopheles gambiae sensu strico and Anopheles arabiensis sibling species of Anopheles gambiae sensu lato complex. In this study, we report further on the accuracy of this tool for simultaneously estimating the age class and differentiating the morphologically indistinguishable An. gambiae s.s. and An. arabiensis from semi-field releases and wild populations. Nine different ages (1, 3, 5, 7, 9, 11, 12, 14, 16 d) of An. arabiensis and eight different ages (1, 3, 5, 7, 9, 10, 11, 12 d) of An. gambiae s.s. maintained in 250 x 60 x 40 cm cages within a semi-field large-cage system and 105 wild-caught female An. gambiae s.l., were included in this study. NIRS classified female An. arabiensis and An. gambiae s.s. maintained in semi-field cages as <7 d old or ≥7 d old with 89% (n = 377) and 78% (n = 327) accuracy, respectively, and differentiated them with 89% (n = 704) accuracy. Wild caught An. gambiae s.l. were identified with 90% accuracy (n = 105) whereas their predicted ages were consistent with the expected mean chronological ages of the physiological age categories determined by dissections. These findings have importance for monitoring control programmes where reduction in the proportion of older mosquitoes that have the ability to transmit malaria is an important outcome.

Age-grading of insects is important in the control and monitoring of both insect populations and vector-borne diseases. Microscopy and morphological techniques exist to age-grade most blood-feeding flies, but these techniques are laborious, often destructive to the insects, and slow. Near-infrared spectroscopy (NIRS) can be automated and is a non-destructive technique for age-grading. We applied NIRS techniques to age-grade females of the biting midge, Culicoides sonorensis Wirth & Jones (Diptera: Ceratopogonidae), the vector of bluetongue and other arboviruses in North America. Female flies of five known age cohorts (1, 3, 6, 9 and 12 days post-emergence) from three laboratory colonies were used. The data indicate that NIRS can be used to differentiate age groups of C. sonorensis.