Search Results (365)

Insecticide resistance monitoring is essential for effective mosquito control. This study compared CDC Bottle Bioassays (BBAs) using technical and formulated insecticides (deltamethrin/Deltagard and malathion/Fyfanon EW) against the Culex pipiens complex (Fogg Rd) and Culex tarsalis Coquillett (Vic Fazio). BBAs indicated resistance to deltamethrin and emerging resistance to malathion in Fogg Rd, as well as resistance to both in Vic Fazio. Field trials, however, showed high efficacy: Deltagard caused 97.7% mortality in Fogg Rd and 99.4% in Vic Fazio. Fyfanon EW produced 100% mortality in Fogg Rd but only 47% in Vic Fazio. Extended BBA endpoints at 120 and 180 min aligned better with field outcomes. Deltagard achieved 100% mortality at 120 min in both populations; technical deltamethrin reached 85.7% (Fogg Rd) and 83.5% (Vic Fazio) at 180 min. Fyfanon EW and malathion showed similar performance: 100% mortality was achieved in Fogg Rd by 120 min but was lower in Vic Fazio; malathion reached 55%; and Fyfanon EW reached 58.6% by 180 min. Statistical analysis confirmed that BBAs using formulated products better reflected field performance, particularly when proprietary ingredients were involved. These findings support the use of formulated products and extended observation times in BBAs to improve operational relevance and resistance interpretation in addition to detecting levels of insecticide resistance. Full article

Arboviruses are a growing concern in many nations. Several reports of arboviral outbreaks have been recorded globally in the past decade alone. Repeated arboviral outbreaks in developing countries have consistently highlighted vulnerabilities in disease surveillance and response systems, exposing critical gaps in early detection, contact tracing, and resource allocation. The 2024 Dengue fever outbreak in Ghana, which recorded 205 confirmed cases out of 1410 suspected cases, underscored the urgent need to evaluate the country’s preparedness for arboviral outbreaks, given the detection of competent vectors in the country. A retrospective analysis of Ghana’s 2009–2013 pandemic influenza response plan revealed significant deficiencies in emergency preparedness, raising concerns about the country’s ability to manage emerging arboviral threats. This review assessed Ghana’s current arboviral outbreak response and preparedness by examining (a) the effectiveness of vector control measures, (b) the role of early warning systems in mitigating outbreaks, (c) laboratory support and diagnostic capabilities, and (d) community engagement strategies. It highlights the successes made in previous outbreaks and sheds light on several gaps in Ghana’s outbreak response efforts. This review also provides recommendations that can be implemented in many countries across Africa as they brace themselves for any arboviral outbreak. Full article

We report the case of a 5-year-old boy from a Sri Lankan migrant family in Catania, Italy, diagnosed with a Dirofilaria repens infection in the spermatic cord. The child presented with pain and swelling in the left inguinal area. Initial evaluation suggested orchiepididymitis, which was treated unsuccessfully with amoxicillin/clavulanate and NSAIDs. As symptoms worsened, torsion of the Morgagni hydatid was considered. An exploratory surgery revealed a firm mass in the left spermatic cord. Histopathological examination of the excised lesion showed fragments of a helminth within a granulomatous inflammatory reaction. Subsequent PCR analysis detected D. repens DNA. The patient fully recovered after surgical excision of the mass. Given the increasing incidence of human dirofilariasis, D. repens should be considered in the differential diagnosis of unexplained subcutaneous or inguinal nodules, especially in patients with a relevant travel history. This case highlights the importance of accurate diagnosis to avoid unnecessary invasive procedures or prolonged antimicrobial therapies. It represents one of the youngest pediatric cases with genital involvement reported in Italy, a country that accounts for half of the cases in Europe. Full article

Human granulocytic anaplasmosis (HGA) is an emerging zoonosis in Europe, with limited data available from Spain. This study aimed to quantify HGA cases in the Spanish National Health System over the last 26 years, assess its evolution, and evaluate the impact in terms of hospital stay and cost. A retrospective observational case series was conducted using the Minimal Basic Data Set (MBDS, CMBD in Spanish). Hospitalized patients with ICD-9-CM and ICD-10 codes for anaplasmosis from 1997 to 2022 were included. Ten HGA cases were reported. The incidence remained stable at one case per year [IR = 0.021 cases/million person-years], except in 2018 [IR = 0.048]. Six patients (60%) were men, with a mean age of 49 years (±20.9). Hospital stays ranged from 3 to 13 days. The total cost was EUR 45,540.57, with an average cost of EUR 4554.06 (±1032.16) per case. All patients had favorable outcomes. HGA has a low incidence in Spain, with moderate associated costs. Despite its emergence, its economic and health impact remains manageable, underscoring the effectiveness of Spain’s healthcare system. Continued surveillance and prevention are essential to address evolving vector-borne diseases. Full article

Triatoma dimidiata is a widely distributed vector of Trypanosoma cruzi in Mexico and Central America, found across a range of habitats from sylvatic to domestic. Vector control has relied heavily on indoor residual spraying with pyrethroids; however, reinfestation and emerging resistance have limited its long-term effectiveness. In this study, we analyzed the genetic diversity and population structure of T. dimidiata from Veracruz, Oaxaca, and Yucatan using mitochondrial markers (cyt b and ND4) and screened for knockdown resistance (kdr)-type mutations in the voltage-gated sodium channel (VGSC) gene. High haplotype diversity and regional differentiation were observed, with most genetic variation occurring between populations. The ND4 marker provided greater resolution than cyt b, revealing ten haplotypes and supporting evidence of recent population expansion. Haplotype networks showed clear geographic segregation, particularly between populations east and west of the Isthmus of Tehuantepec. The L925I mutation, highly associated with pyrethroid resistance, was detected for the first time in Mexican populations of T. dimidiata, albeit at low frequencies. These findings highlight the importance of integrating population genetic data and resistance surveillance into regionally adapted vector control strategies for Chagas disease. Full article

The private sector in Tanzania has played an essential role in improving coverage and access to mosquito nets. This follow-up study assessed the overall market share for untreated and insecticide-treated nets (ITNs) and misleading or counterfeit ITN products in commercial markets. This study was conducted from March to April 2024 in ten regions in Tanzania. The study used mixed methods: (1) a quantitative survey among sampled outlets supported by photographic documentation of all net products and (2) key informant interviews of retailers and wholesalers. We assessed the relationship between market share and population access using ANOVA and Pearson correlation. No counterfeit or misleading nets were found, consistent with results from 2017, 2021, and 2022 surveys. Untreated nets dominated all markets, comprising 99% of all products observed and 99% of estimated net sales 3 months before the survey. Legitimate ITNs were crowded out from the studied markets. Leaked nets from free distributions were present but extremely limited (1%) and at their lowest level of the survey rounds. Untreated nets were more expensive than leaked ITNs for both regular- and queen-size nets. Despite ongoing efforts, increasing the share of legitimate ITNs remains a significant challenge in a context of large-scale public sector distributions. Full article

Democratic Republic of the Congo (DRC) is among the countries that have a high malaria incidence. In an effort to combat this public health challenge, innovative tools and strategies are being developed and evaluated. Among the new generation of nets with improved effectiveness of insecticides, those treated with a combination of piperonyl butoxide (PBO) and pyrethroids appear to be a promising malaria control tool. This study evaluated the effectiveness of this combination under community conditions of use in the DRC. A quasi-experimental study was carried out from January to December 2018, in Kisantu Health Zone. Thirty villages were randomly allocated as clusters (1:1) to receive one of two types of long-lasting insecticidal nets (LLIN) treated with deltamethrin alone, or PBO with deltamethrin. After the intervention, the assessments were conducted monthly, quarterly, and every six months for malaria infection, mosquito density, and LLIN durability, respectively. Comparison of changes in different indices between the two groups was made using generalized linear models to correct for non-linear effects. A total of 1790 children were included. There was a significant non-linear effect of time (months) on the malaria infection incidence. The malaria infection incidence was higher in January–March, May–June, and November. It remained higher in the control group compared to the intervention group over time. Similarly, there was a significant non-linear effect of time on the density of both Anopheles funestus s.l. and Anopheles gambiae s.l. These densities decreased after the first month following the intervention and increased after 6 months. Twelve months later, a cohort follow-up showed that the bio-efficacy of LLINs was better in the intervention group. The nets treated with the combination of PBO and deltamethrin appear to be more effective for malaria control under community conditions in the DRC, but a loss of chemical durability is noted after the first year of use. Full article

The rapid global expansion of Aedes aegypti-borne diseases such as dengue, chikungunya, and Zika has positioned this mosquito as a key target for vector control programs. These programs rely heavily on insecticide use, leading to the widespread emergence of insecticide resistance. Understanding the molecular basis of resistance is essential for developing effective management strategies. In this study, we employed a whole-transcriptome (RNA-seq) approach to analyze gene expression in three Ae. aegypti populations from Mexico that underwent four generations of laboratory selection with deltamethrin. Several cytochrome P450 genes (CYP6AG4, CYP6M5, CYP307A1) and a chitin-binding peritrophin-like gene (Ae-Aper50) were significantly overexpressed following selection, supporting roles for both detoxification and midgut protection. We also observed a consistent downregulation of cuticular protein genes in deltamethrin-selected groups relative to the baseline populations, suggesting their involvement in baseline tolerance rather than induced resistance. Additionally, the overexpression of immune- and stress-related genes, including the RNA helicase MOV-10, indicates that insecticide selection may trigger broader physiological responses. These findings highlight complex, multi-pathway transcriptomic changes associated with resistance development in Ae. aegypti. Full article

Aedes aegypti, the main urban vector of dengue fever, represents a growing public health problem in Nouakchott, the capital of Mauritania. Identifying the factors influencing the distribution and productivity of its breeding sites is essential for the development of effective control strategies. From May 2023 to April 2024, physico-chemical characteristics were recorded and mosquito larvae were collected, using a standard dipping method, from 60 water collections each month during the dry season and twice a month during the rainy season, totaling 294 observations. The larval positivity of water collections and larval abundance of breeding sites over the time were modeled using a random-effect logistic regression model and a negative binomial regression model, respectively. The depth, distance from habitat, type of water collection and exposure to sunlight were statistically significant and independently associated with water collection positivity for Ae. aegypti larvae (aOR = 5.18, 95%CI [1.66–16.18], p-value = 0.005; aOR = 0.00, 95%CI [0.00–0.02], p-value < 0.001; aOR = 252.88, 95%CI [4.05–15,786.84], p-value = 0.009 and aOR = 0.04, 95%CI [0.01–0.26], p-value < 0.001, respectively). Aedes aegypti larval habitats were mainly artificial (90%), temporary (n = 217 observations), close to dwellings (n = 114) and shaded (n = 96). Plastic water tanks (n = 17, 48.6%), wells (n = 6, 17.1%) and barrels (n = 4, 11.4%) were the most common breeding sites. Larval abundance was negatively associated with containers of increasing pH and surface area (aOR = 0.50, 95%CI [0.33–0.75] p-value = 0.001 and aOR = 0.48, 95%CI [0.27–0.87], p-value = 0.016, respectively). As Ae. aegypti mosquitoes are multi-resistant to adult insecticides and dengue has become endemo-epidemic since 2014, vector control should give the priority to the physical removal or treatment of shaded, peridomestic containers—particularly plastic water tanks and barrels—and consider the use of biological larvicides to target breeding sites with low pH and small surface areas. Full article

Background: Recent setbacks in malaria control in Comoros demand a reassessment of its evolving epidemiology. Methods: Using the Global Burden of Disease (GBD) Study 2021 data, we analyzed malaria trends from 2010 to 2021, stratified by sex. We quantified the contributions of demographic and epidemiological factors to these trends and identified risk factors for malaria-related disability-adjusted life years (DALYs). Results: From 2010 to 2021, malaria cases, deaths, and DALYs in Comoros fell by −90.22%, −94.44%, and −94.88%; and the corresponding age-standardized rates declined with EAPCs of −18.70% (95% CI: −33.77 to −0.20), −23.89% (95% CI: −36.58 to −8.66), and −24.49% (95% CI: −36.88 to −9.66), with steeper declines in males. Nevertheless, all indicators increased in 2018 and again in 2021. In sub-Saharan Africa, only cases increased, while other metrics declined slightly. In Comoros, incidence shifted mainly to adults ≥25 years, unlike sub-Saharan Africa, where children < 5 years were most affected. Population growth drove increases in cases, deaths and DALYs, whereas epidemiological shifts had the opposite effect. Child underweight was the leading risk factor for malaria DALYs. Conclusions: Existing interventions can achieve malaria control in Comoros; however, rebounds in 2018 and 2021 highlight the need to identify and address drivers of resurgence. Full article

Altered lipid profiles have been observed in acute malaria, though mechanisms remain unclear. The impact of asymptomatic submicroscopic malaria infection (AMI) on lipids is unexploredAn observational, comparative, retrospective study was conducted of 1278 asymptomatic Sub-Saharan African migrants (ASSAMs) screened for malaria and lipid profiles during health exams (2010–2022). A systematic screening protocol for infectious disease was performed, including screening for Plasmodium spp. infection by polymerase chain reaction (PCR).Among 800 ASSAMs screened for malaria, 104 (13%) were PCR-positive: P. falciparum (68.72%), P. malariae (18.27%), P. ovale (9.62%), and mixed infections (3.8%). Participants with AMIs exhibited lower baseline lipid levels: total cholesterol (146 vs. 163 mg/dL; p < 0.001), HDL (43 vs. 47 mg/dL; p < 0.001), and LDL (87.5 vs. 98 mg/dL; p < 0.001), with no differences in triglycerides. After treatment, lipid levels partially equalized: total cholesterol (156 vs. 166; p = 0.01), HDL (44 vs. 47.5; p = 0.05), LDL (102 vs. 108.5; p = 0.31), with no changes in triglycerides. Patients with AMI showed higher rates of co-infections (Strongyloides 20.61% vs. 14.35%; p < 0.001; filariae 7.69% vs. 1.91%; p = 0.02) and lower mean corpuscular volume (87.2 vs. 85; p < 0.001). Conclusions: These findings suggest that cholesterol reductions in AMI are not solely due to acute inflammation but may reflect chronic inflammatory processes triggered by asymptomatic malaria. This supports a potential link between AMI and lipid profile changes, underscoring its role in subclinical chronic inflammation. Full article

Leishmaniasis is a complex neglected tropical disease that impacts public health, particularly in resource-limited populations where access to accurate and timely diagnosis is often limited. Current diagnostic methods, primarily relying on microscopy, suffer from low sensitivity and specificity, hindering effective case management and disease control. The objective of this study was to validate a novel real-time PCR assay targeting the conserved Hsp20 gene for the detection of Leishmania spp. We evaluated the performance of the method using two distinct detection systems, such as SYBR Green and TaqMan probes, against a diverse panel of 225 clinical samples confirmed to have the disease. The real-time PCR targeting Hsp20 using SYBR Green demonstrated a sensitivity of 88% (95% CI: 83.53–92.47) and 100% specificity. Meanwhile, the TaqMan probe demonstrated a lower sensitivity of 47% (95% CI: 29.53–64.92). The high sensitivity and robust performance of the real-time PCR using SYBR Green establish its potential as a valuable diagnostic tool, particularly useful in endemic regions where rapid and accurate diagnosis is critical for timely treatment and effective disease control. Full article

New intervention methods and product formulations are needed to better control pyrethroid-resistant Aedes aegypti populations and mitigate the risk of mosquito-borne disease. ReMoa Tri is a novel adulticidal space spray that utilizes a different mode of action than the commonly used adulticides: pyrethroids and organophosphates. As a triple-action space spray, ReMoa Tri combines three components: Fenpropathrin, a mixed-type I/II pyrethroid; abamectin, a macrocyclic lactone; and C8910, a patented fatty acid chain. Prior studies performed by Collier Mosquito Control District showed that ReMoa Tri is effective at controlling type I pyrethroid-resistant Ae. aegypti mosquitoes. To further validate these results and the performance of ReMoa Tri, we conducted a semi-field evaluation using ground and aerial ULV (ultra-low volume) applications with field-caught deltamethrin-resistant Ae. aegypti and a susceptible Ae. aegypti laboratory strain. Ground evaluations tested ReMoa Tri and a type II pyrethroid-based product, DeltaGard. While ReMoa Tri was equally effective against Collier’s deltamethrin-resistant Ae. aegypti and the susceptible laboratory strain, DeltaGard was effective against both strains, with reduced efficacy at farther distances. Similarly, aerial evaluations also showed that ReMoa Tri was equally effective against Collier’s deltamethrin-resistant Ae. aegypti strain and susceptible laboratory strain. This study further confirms ReMoa Tri’s potential as an effective alternative to pyrethroid-based adulticides, both in ground and aerial applications, for managing pyrethroid-resistant Ae. aegypti. Full article

This study examines the desiccation tolerance of Aedes aegypti and Aedes albopictus eggs, two major arbovirus vectors, in a subtropical region of Argentina to understand their survival under varying relative humidity (RH) conditions (35%, 68%, and 82%). Laboratory experiments revealed that Ae. aegypti eggs exhibited significantly higher survival rates across all RH levels and exposure times compared to Ae. albopictus. After 1 month, Ae. aegypti eggs maintained 88% survival at 35% RH, while Ae. albopictus survival dropped to 38%. This disparity was more pronounced at low RH, where Ae. albopictus eggs experienced a rapid decline in survival over time. The results highlight the importance of RH as a key factor influencing the persistence of both species in the environment. The coexistence of Ae. aegypti and Ae. albopictus in Puerto Iguazú suggests that microhabitats with distinct humidity conditions may favor one species over the other. These findings provide crucial insights for predicting mosquito population dynamics under changing climate conditions and developing more effective vector control strategies to reduce arbovirus transmission in subtropical regions. Full article

Chagas disease is a neglected disease caused by the parasite Trypanosoma cruzi, a public health problem in both endemic and non-endemic countries. In Mexico, the southern region is considered endemic, and cases are frequently reported; however, in the northwestern region, only a few cases are confirmed annually. This study describes, for the first time, the Discrete Typing Unit (DTU) of Trypanosoma cruzi in a volunteer blood donor rejected for being reactive in the northwestern region of Mexico. Seroreactivity was confirmed using “in-house” ELISAs which employed three different antigens: total extract from Trypanosoma cruzi isolated from a vector (Triatoma rubida) from Sonora (strain T1), strain H1 and CL-Brener. The molecular characterization of Trypanosoma cruzi was conducted by amplifying satellite DNA by qPCR and posterior sequencing of the mini-exon gene, using Next Generation Sequencing (NGS) to enhance the accuracy of genetic characterization. The results show that the reactive status of this blood donor was confirmed using our in-house ELISAs, and the presence of Trypanosoma cruzi by detecting TcI DTU confirmed the infection status. Full article