Electropenetrography with Alternating Current Reveals In Situ Changes of Aedes aegypti Probing Behaviors Associated with Dengue Virus Infection.

Human infection with dengue virus (DENV) results in significant morbidity and mortality around the world. Current methods to investigate virus-associated changes in insect feeding behaviors are largely restricted to video analysis of feeding events outside of the host or intravital microscopy. Electropenetrography, a method originally developed for plant-feeding insects, offers a promising alternative by allowing high-resolution recording of voltage changes across the insect bite interface. We compared recordings from DENV-infected Aedes aegypti mosquitoes feeding on uninfected mice and uninfected A. aegypti feeding on DENV-infected mice to controls of uninfected A. aegypti feeding on uninfected mice. We found significant mosquito behavioral changes in both DENV-infected groups compared with controls including longer feeding times and longer preingestion probing events for A. aegypti feeding on DENV-infected mice and a higher number of sequential probing events in DENV-infected A. aegypti feeding on uninfected mice. By recording mosquito feeding and probing events beneath the surface of the skin, we have been able to both confirm and add new dimensions to previous findings regarding DENV-associated behavior changes in A. aegypti. This provides a foundation for increasingly in-depth studies focusing on the transmission of the DENV between vectors and hosts.

Erratum: AC-DC Electropenetrography as a Tool to Quantify Probing and Ingestion Behaviors of the Yellow Fever Mosquito (Aedes aegypti) on Mice in Biocontainment.

This corrects the article DOI: 10.30802/AALAS-CM-23-000037
When the above article was first published in the Vol 3 No 6 (December 2023) issue of Comparative Medicine, figure images were incorrectly associated with the figure legends. The correct version of this article has been reprinted in full in volume 74, issue 1 of the February issue of Comparative Medicine.
The publisher apologizes for this error and any inconvenience caused.

Artificial Feeding Systems for Vector-Borne Disease Studies.

This review examines the advancements and methodologies of artificial feeding systems for the study of vector-borne diseases, offering a critical assessment of their development, advantages, and limitations relative to traditional live host models. It underscores the ethical considerations and practical benefits of such systems, including minimizing the use of live animals and enhancing experimental consistency. Various artificial feeding techniques are detailed, including membrane feeding, capillary feeding, and the utilization of engineered biocompatible materials, with their respective applications, efficacy, and the challenges encountered with their use also being outlined. This review also forecasts the integration of cutting-edge technologies like biomimicry, microfluidics, nanotechnology, and artificial intelligence to refine and expand the capabilities of artificial feeding systems. These innovations aim to more accurately simulate natural feeding conditions, thereby improving the reliability of studies on the transmission dynamics of vector-borne diseases. This comprehensive review serves as a foundational reference for researchers in the field, proposing a forward-looking perspective on the potential of artificial feeding systems to revolutionize vector-borne disease research.

An electropenetrography waveform library for the probing and ingestion behaviors of Culex tarsalis on human hands.

Culex tarsalis Coquillett (Diptera: Culicidae) mosquitoes are capable of vectoring numerous pathogens affecting public and animal health. Unfortunately, the probing behaviors of mosquitoes are poorly understood because they occur in opaque tissues. Electropenetrography (EPG) has the potential to elucidate these behaviors by recording the electrical signals generated during probing. We used an AC-DC EPG with variable input resistors (Ri levels) to construct a waveform library for Cx. tarsalis feeding on human hands. Biological events associated with mosquito probing were used to characterize waveforms at four Ri levels and with two electrical current types. The optimal settings for EPG recordings of Cx. tarsalis probing on human hands was an Ri level of 107 Ohms using an applied signal of 150 millivolts alternating current. Waveforms for Cx. tarsalis included those previously observed and associated with probing behaviors in Aedes aegypti L. (Diptera: Culicidae): waveform families J (surface salivation), K (stylet penetration through the skin), L (types 1 and 2, search for a blood vessel/ingestion site), M (types 1 and 2, ingestion), N (type 1, an unknown behavior which may be a resting and digestion phase), and W (withdrawal). However, we also observed variations in the waveforms not described in Ae. aegypti, which we named types L3, M3, M4, and N2. This investigation enhances our understanding of mosquito probing behaviors. It also provides a new tool for the automated calculation of peak frequency. This work will facilitate future pathogen acquisition and transmission studies and help identify new pest and disease management targets.

Development of an automated biomaterial platform to study mosquito feeding behavior.

Mosquitoes carry a number of deadly pathogens that are transmitted while feeding on blood through the skin, and studying mosquito feeding behavior could elucidate countermeasures to mitigate biting. Although this type of research has existed for decades, there has yet to be a compelling example of a controlled environment to test the impact of multiple variables on mosquito feeding behavior. In this study, we leveraged uniformly bioprinted vascularized skin mimics to create a mosquito feeding platform with independently tunable feeding sites. Our platform allows us to observe mosquito feeding behavior and collect video data for 30-45 min. We maximized throughput by developing a highly accurate computer vision model (mean average precision: 92.5%) that automatically processes videos and increases measurement objectivity. This model enables assessment of critical factors such as feeding and activity around feeding sites, and we used it to evaluate the repellent effect of DEET and oil of lemon eucalyptus-based repellents. We validated that both repellents effectively repel mosquitoes in laboratory settings (0% feeding in experimental groups, 13.8% feeding in control group, p < 0.0001), suggesting our platform's use as a repellent screening assay in the future. The platform is scalable, compact, and reduces dependence on vertebrate hosts in mosquito research.

Aedes aegypti and Aedes albopictus (Diptera: Culicidae) Oviposition Activity and the Associated Socio-environmental Factors in the New Orleans Area.

The transmission of Aedes-borne viruses is on the rise globally. Their mosquito vectors, Aedes aegypti (Linnaeus, Diptera: Culicidae) and Ae. albopictus (Skuse, Diptera: Culicidae), are focally abundant in the Southern United States. Mosquito surveillance is an important component of a mosquito control program. However, there is a lack of long-term surveillance data and an incomplete understanding of the factors influencing vector populations in the Southern United States. Our surveillance program monitored Ae. aegypti and Ae. albopictus oviposition intensity in the New Orleans area using ovicups in a total of 75 sites from 2009 to 2016. We found both Aedes spp. throughout the study period and sites. The average number of Ae. aegypti and Ae. albopictus hatched from collected eggs per site per week was 34.1 (SD = 57.7) and 29.0 (SD = 46.5), respectively. Based on current literature, we formed multiple hypotheses on how environmental variables influence Aedes oviposition intensity, and constructed Generalized Linear Mixed Effect models with a negative binomial distribution and an autocorrelation structure to test these hypotheses. We found significant associations between housing unit density and Ae. aegypti and Ae. albopictus oviposition intensity, and between median household income and Ae. albopictus oviposition intensity. Temperature, relative humidity, and accumulated rainfall had either a lagged or an immediate significant association with oviposition. This study provides the first long-term record of Aedes spp. distribution in the New Orleans area, and sheds light on factors associated with their oviposition activity. This information is vital for the control of potential Aedes-borne virus transmission in this area.

Clinical presentations of erosive esophagitis found at endoscopy in neurologically impaired children: a historical study.

BACKGROUND: Data is lacking as to the clinical presentation of erosive esophagitis (EE) in neurologically impaired children compared to non-neurologically impaired children (non-NIC). To determinate the clinical presentation, associations, management, and outcomes of EE in neurologically impaired children compared to children without neurologic impairment. METHODS: Retrospective chart review of all esophagogastroduodenoscopies performed in pediatric patients at the University of Mississippi Medical Center from 1998 to 2020 with the diagnosis of EE. Fisher's exact test was used to compare results from neurologically impaired children group and non-NIC. A probability <0.05 was considered statistically significant. RESULTS: Forty-seven patients were diagnosed with EE and met study criteria. Twenty-six patients were neurologically impaired children, and 21 were non-neurologically impaired children. No significant difference was seen between age at diagnosis, sex, or hematologic markers of anemia. The most common indication for esophagogastroduodenoscopies in neurologically impaired children was hematemesis (65.4%), whereas abdominal pain (33.3%) was the most common in non-NIC. Neurologically impaired children were more likely to be treated with acid-blockade. Nine neurologically impaired children had gastrostomy tubes prior to diagnosis as opposed to 0 non-neurologically impaired children. After diagnosis, 8 neurologically impaired children underwent gastrostomy tube placement compared to 0 non-neurologically impaired children, and fundoplication was performed in 11 neurologically impaired children as compared to 1 non-NIC. The sensitivity of fecal occult blood test for detecting EE was higher for neurologically impaired children (91.7%) than for non-NIC (33.3%). CONCLUSIONS: EE in neurologically impaired children presents differently than in non-neurologically impaired children with blood loss being the most common presentation in neurologically impaired children. Neurologically impaired children are more likely to be treated with acid-blockade prior to diagnosis, likely due to heightened risk for gastroesophageal reflux disease (GERD). Additionally, they are more likely to undergo surgical management of EE than non-neurologically impaired children.

An Electronic Pre-Exposure Prophylaxis Initiation and Maintenance Home Care System for Nonurban Young Men Who Have Sex With Men: Protocol for a Randomized Controlled Trial.

BACKGROUND: Pre-exposure prophylaxis (PrEP) is highly efficacious for preventing HIV but has not yet been brought to scale among at-risk persons. In several clinical trials in urban areas, technology-based interventions have shown a positive impact on PrEP adherence. In rural and small-town areas in the United States, which often do not have geographically proximal access to PrEP providers, additional support may be needed. This may be particularly true for younger persons who are more likely to face multiple barriers to accessing PrEP services. Home-based care, accomplished through a tailored mobile phone app, specimen self-collection (SSC), and interactive video consultations, could increase both PrEP initiation and persistence in care. OBJECTIVE: The goal of this study is to assess the initiation and persistence in PrEP care for those randomized to a home-care intervention (electronic PrEP, ePrEP) relative to those assigned to the standard of care (control) condition. We will conduct additional assessments, including quantitative and qualitative analyses, to contextualize trial results and facilitate scale-up. METHODS: This 2-arm, randomized controlled trial will enroll young men who have sex with men (YMSM) aged between 18 and 24 years from rural areas of Georgia, Mississippi, and North Carolina. The trial will seek to recruit a diverse sample, targeting 50% participation among highly impacted groups of black or Latino men who have sex with men. Intervention participants will receive a study app that incorporates a messaging platform, a scheduling and milestone-based tracking system for PrEP care progress, electronic behavioral surveys, and interactive video consultations with a clinician. Complemented by SSC kits mailed to laboratories for standard PrEP-related monitoring, the ePrEP system will allow participants to access PrEP care without leaving their homes. YMSM randomized to the control condition will receive a listing of nearest local PrEP providers to receive standard PrEP care. Both groups will complete quarterly electronic surveys. The primary outcome, assessed at 6 and 12 months after randomization, will be the difference in the proportion of intervention versus control participants that achieve protective levels of the active metabolite of oral PrEP (tenofovir diphosphate in dried blood spots). RESULTS: Enrollment will begin in May 2019, with study completion in 2022. CONCLUSIONS: This trial will determine whether home PrEP care provided through an app-based platform is an efficacious means of expanding access to PrEP care for a diverse group of YMSM in rural and small-town areas of the United States. TRIAL REGISTRATION: ClinicalTrials.gov NCT03729570; https://clinicaltrials.gov/ct2/show/NCT03729570 (Archived by WebCite at http://www.webcitation.org/78RE2Qizf). INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): PRR1-10.2196/13982.

Field Surveillance Methods for West Nile Virus.

Surveillance of West Nile virus (WNV) in populations of mosquitoes or sentinel animals is of primary importance when assessing the risks to human health posed by naturally circulating WNV. In this chapter we focus on methods for detection of both WNV and its enzootic transmission. Methods for virus detection include CDC mini light trap, CDC gravid trap, and dead bird surveillance. Methods for transmission detection include passive box traps, chicken-baited traps, and sentinel chickens.

Evidence of limited polyandry in a natural population of Aedes aegypti.

The mosquito Aedes aegypti is a vector of yellow fever, dengue, and chikungunya. Control of the insect is crucial to stop the spread of dengue and chikungunya, so it is critically important to understand its mating behavior. Primarily, based on laboratory behavior, it has long been assumed that Ae. aegypti females mate once in their lifetime. However, multiple inseminations have been observed in semi-field and laboratory settings, and in closely related species. Here, we report the first evidence of polyandry in a natural population of Ae. aegypti. Female Ae. aegypti were captured around the New Orleans, LA, metropolitan area. They were offered a blood meal and allowed to lay eggs, which were reared to the third-instar larval stage. A parentage analysis using four microsatellite loci was performed. Out of 48 families, 3 showed evidence of multiple paternity. An expanded analysis of these three families found that one family group included offspring contributed by three fathers, and the other two included offspring from two fathers. This result establishes that polyandry can occur in a small proportion of Ae. aegypti females in a natural setting. This could complicate future genetic control efforts and has implications for sampling for population genetics.

Genotype diversity of Trypanosoma cruzi in small rodents and Triatoma sanguisuga from a rural area in New Orleans, Louisiana.

BACKGROUND: Chagas disease is an anthropozoonosis caused by the protozoan parasite Trypanosoma cruzi that represents a major public health problem in Latin America. Although the United States is defined as non-endemic for Chagas disease due to the rarity of human cases, the presence of T. cruzi has now been amply demonstrated as enzootic in different regions of the south of the country from Georgia to California. In southeastern Louisiana, a high T. cruzi infection rate has been demonstrated in Triatoma sanguisuga, the local vector in this area. However, little is known about the role of small mammals in the wild and peridomestic transmission cycles. METHODS: This study focused on the molecular identification and genotyping of T. cruzi in both small rodents and T. sanguisuga from a rural area of New Orleans, Louisiana. DNA extractions were prepared from rodent heart, liver, spleen and skeletal muscle tissues and from cultures established from vector feces. T. cruzi infection was determined by standard PCR using primers specific for the minicircle variable region of the kinetoplastid DNA (kDNA) and the highly repetitive genomic satellite DNA (satDNA). Genotyping of discrete typing units (DTUs) was performed by amplification of mini-exon and 18S and 24Sα rRNA genes and subsequent sequence analysis. RESULTS: The DTUs TcI, TcIV and, for the first time, TcII, were identified in tissues of mice and rats naturally infected with T. cruzi captured in an area of New Orleans, close to the house where the first human case of Chagas disease was reported in Louisiana. The T. cruzi infection rate in 59 captured rodents was 76%. The frequencies of the detected DTUs in such mammals were TcI 82%, TcII 22% and TcIV 9%; 13% of all infections contained more than one DTU. CONCLUSIONS: Our results indicate a probable presence of a considerably greater diversity in T. cruzi DTUs circulating in the southeastern United States than previously reported. Understanding T. cruzi transmission dynamics in sylvatic and peridomestic cycles in mammals and insect vectors will be crucial to estimating the risk of local, vector-borne transmission of T. cruzi to humans in the United States.

Factors associated with peridomestic Triatoma sanguisuga (Hemiptera: Reduviidae) presence in southeastern Louisiana.

Although rare, there have been isolated reports of autochthonous transmission of Trypanosoma cruzi Chagas in the United States. In June 2006, a human case of domestically transmitted T. cruzi was identified in southern Louisiana. To examine the localized risk of human T. cruzi infection in the area surrounding the initial human case, environmental surveys of households in the area and a serological survey of the residents were performed between September 2008 and November 2009. Human T. cruzi infection was determined using a rapid antigen field test, followed by confirmatory enzyme-linked immunosorbent assay testing in the laboratory. A perimeter search of each participating residence for Triatoma sanguisuga (LeConte), the predominant local triatomine species, was also performed. No participating individuals were positive for antibodies against T. cruzi; however, high levels of T. cruzi infection (62.4%) were detected in collected T. sanguisuga. Households with T. sanguisuga presence were less likely to use air conditioning, and more likely to have either chickens or cats on the property. While the human risk for T cruzi infection in southeastern Louisiana is low, a high prevalence of infected T. sanguisuga does indicate a substantial latent risk for T. cruzi peridomestic transmission. Further examination of the behavior and ecology of T. sanguisuga in the region will assist in refining local T. cruzi risk associations.