Effect of Environmental Temperature and Humidity on Permethrin Biomarkers of Exposure in U.S. Soldiers Wearing Permethrin-Treated Uniforms

Reduced effectiveness of permethrin-treated military uniforms after prolonged wear measured by contact irritancy and toxicity bioassays with Ixodes scapularis (Acari: Ixodidae) nymphs

Factory-treated permethrin uniforms are the primary method used by the US Army to prevent arthropod bites and transmission of arthropod-borne diseases. In this study previously worn uniforms were collected from cadets at the United States Military Academy in West Point, NY to determine the amount of permethrin remaining after prolonged wear and subsequent effects on ticks. Six trousers were collected from cadets in the sophomore, junior, and senior classes. A new, unwashed uniform served as a positive control and an untreated maternity uniform served as a negative control. Fabric samples were removed from each trouser and used in bioassays with laboratory-reared Ixodes scapularis Say nymphs. Contact irritancy bioassays measured the nymphs' ability to remain in contact with fabric for a period of 5 min. Toxicity bioassays measured tick survival at 1 and 24 h after contacting uniform samples. liquid chromatography-mass spectrometry was used to quantify the permethrin content (mg/cm2) in each uniform after the bioassays were complete. The results showed significant amounts of permethrin were lost after extended wear and it was related to the cadet year group. The contact irritancy assays found uniforms with less permethrin did not irritate ticks and cause them to dislodge. Mortality was also affected by permethrin levels, with less ticks dying at 24 h on older uniforms. The results from this study show older uniforms lose most of their permethrin and no longer provide the same levels of protection.

Improving care for veterans' environmental exposure concerns: applications of the consolidated framework for implementation research in program evaluation

BACKGROUND

Healthcare systems, like the US Department of Veterans Affairs (VA), need policies and procedures for delivering care to special populations including those with environmental exposure concerns. Despite being common and pervasive, especially among Veterans, environmental exposures are largely overlooked by healthcare providers. To successfully implement care for Veterans with military environmental exposure concerns, an understanding of contextual factors impeding care on the provider (e.g., knowledge and beliefs) and organizational (e.g., leadership's priorities) level is needed. Our goal was to conduct an operational needs assessment of providers to examine provider educational needs regarding Veterans' military environmental exposure concerns.

METHODS

In 2020, we surveyed 2,775 VA medical and behavioral health providers. Our cross-sectional assessment was informed by the Consolidated Framework for Implementation Research (CFIR) and assessed barriers and facilitators to the uptake and application of knowledge regarding interdisciplinary care for environmental exposure concerns. The web-based survey was emailed to providers across the United States representing a variety of disciplines and practice settings to reflect the interdisciplinary approach to care for environmental exposures. We used bivariate statistics to investigate the intervention setting, inner setting, and individual characteristics of providers regarding care for environmental exposure concerns.

RESULTS

Approximately one-third of VA medical and behavioral health clinicians report low to no knowledge of environmental exposure concerns. We find 88% of medical and 91% of behavioral health providers report they are ready to learn more about environmental exposures. Half of medical and behavioral health providers report they have access to information on environmental exposures and less than half report care for environmental exposures is a priority where they practice.

CONCLUSIONS

Our findings suggest interdisciplinary providers' knowledge of and discussion with Veterans about environmental exposures may be influenced by contextual factors at the organizational level. Considering individual-level factors and organizational culture is important to consider when supporting care for environmental exposures. Since this needs assessment, VA established targeted programs to improve care related to military environmental exposures in response to legislation; future exploration of these same variables or contextual factors is warranted.

Individual-level permethrin exposure biomarkers in U.S. army soldiers: comparison of two treatment formulations for military uniforms

BACKGROUND

Evidence suggests that wearing permethrin-treated military uniforms is not associated with current adverse health conditions. However, exposure through this route results in permethrin biomarker concentrations considerably higher than those in the U.S.

POPULATION

The U.S. Army is exploring different methods of uniform treatment that reduce exposure while maintaining effective protection from insect vector-borne diseases.

OBJECTIVE

To compare permethrin exposure when wearing two types of permethrin-treated military uniforms.

METHODS

Eight male soldiers participated in a 32-day crossover design study to compare permethrin exposure when wearing the current Army uniform (CurrU) and a uniform with a new applied fabric treatment (NewU). Each soldier wore the uniforms for designated 8 h/day time periods over 3 consecutive days separated by a 'wash-out' week of no exposure. Permethrin exposure was assessed from the urinary concentrations of 3-phenoxybenzoic acid (3-PBA) and of the sum of cis- and trans-3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane-1-carboxylic acid (∑DCCA). Estimated dose was determined based on ∑DCCA concentrations.

RESULTS

Permethrin exposure biomarkers were 21% (3-PBA, p = 0.025) and 35% (∑DCCA, p < 0.001) lower when wearing the NewU compared to the CurrU; the dose was 33% lower (p = 0.05).

SIGNIFICANCE

Findings suggest the new treatment reduces human permethrin exposure biomarkers resulting from wearing-treated military uniforms.

A Survey Among Cadets at the United States Military Academy on Knowledge and Wearing of Permethrin-Treated Uniforms and the Risk of Tick-Borne Diseases

INTRODUCTION

The Army uses permethrin-treated uniforms as the primary method to protect soldiers from tick-borne diseases. Permethrin binds strongly to fabric and provides long-term protection against many blood-feeding arthropods. However, protection decreases if the uniforms are not washed and cared for according to label instructions. This study was conducted among cadets at the United States Military Academy (USMA) at West Point, NY, to determine what the cadets know about permethrin and how they care for and wear their uniforms. West Point is in an area with high rates of tick-borne disease transmission. A survey was developed to determine what cadets know about the threat of tick-borne diseases and if they wear and maintain their uniforms in a manner that effectively maintains permethrin levels.

MATERIALS AND METHODS

A 16-question survey was developed and submitted to the local review board for approval. The study was classified as human subjects research according to 32CFR219 and met the requirements for exempt status under 32CFR219.104(d)(2)(i). After receiving approval, a hard copy survey was distributed among cadets with efforts to sample at least 50 members from each cadet class.

RESULTS

A total of 319 cadets provided responses to the survey questions, representing more than 7% of the cadet population at the USMA. The results showed most cadets knew their uniforms were treated with permethrin, but less than half knew there are specific instructions attached to their uniforms describing how the uniforms should be laundered. From the cadets who knew there were instructions, most admittedly did not follow the instructions. Sixteen percent of cadets said they had dry-cleaned their uniforms. This is a process known to remove most of the permethrin. The majority of cadets viewed the risk of tick-borne disease at West Point to be moderate or lower.

CONCLUSIONS

This study provides a basic understanding of the wear patterns of permethrin-treated uniforms among cadets at the USMA. It is also one of the few studies to measure knowledge and uniform-wearing behavior among service members since the Army switched to factory-treated uniforms in 2013. The results indicate that compliance with uniform laundry and care instructions is low. This information is useful to develop training plans and educate cadets how they can wear and take care of their permethrin-treated uniforms to better protect themselves from tick-borne diseases.

Assessing Durability and Safety of Permethrin Impregnated Uniforms Used by Outdoor Workers to Prevent Tick Bites after One Year of Use

Long lasting permethrin-impregnated (LLPI) clothing can retain permethrin and repel ticks for up to three months and without exceeding EPA-approved safe levels; however, little is known about longer term effects of wearing LLPI clothing. Here, permethrin content was measured in new forester pants soon after initial impregnation (Insect Shield) and again one year later after being repeatedly worn by foresters in the field. Urine samples were collected from foresters for biomonitoring of permethrin metabolites at multiple time intervals (pre-use, one-month, three-to-four-months, and one-year post-use). Lethality against nymphal Ixodes scapularis Say was measured in clothing after one year of wear by foresters. Furthermore, to test potential variability in permethrin impregnation of different batches of clothing, separate sets of clothing were anonymously sent to Insect Shield for permethrin treatment over a period of three months and permethrin was quantified. Results demonstrated 33% of participants' pants had no measurable permethrin after one year of wear and permethrin content and tick mortality varied significantly between clothing. Only two of the participants' clothing resulted in ≥ 30% tick mortality after one year of wear. Significant differences were observed in 3-PBA and trans-DCCA, but not cis-DCCA metabolites in participants over the four measured time points and were higher than general United States population levels. This study provides practical information on the safety (measured by urinary metabolites) over time of LLPI clothing. It also provides snapshots (pre-washing and after one year of wear) of effectiveness of LLPI clothing as personal protective equipment against ticks for outdoor workers.

Risk factor of plasmodium knowlesi infection in Sabah Borneo Malaysia, 2020: A population-based case-control study

BACKGROUND

In the Malaysian state of Sabah, P. knowlesi notifications increased from 2% (59/2,741) of total malaria notifications in 2004 to 98% (2030/2,078) in 2017. There was a gap regarding P. knowlesi acquisition risk factors related to practice specifically in working age group. The main objective of this study was to identify the risk factors for acquiring P. knowlesi infection in Sabah among the working age group.

METHODS AND METHODS

This retrospective population-based case-control study was conducted in Ranau district to assess sociodemographic, behavioural and medical history risk factors using a pretested questionnaire. The data were entered and analyzed using IBM SPSS version 23. Bivariate analysis was conducted using binary logistic regression whereas multivariate analysis was conducted using multivariable logistic regression. We set a statistical significance at p-value less than or equal to 0.05.

RESULTS

A total of 266 cases and 532 controls were included in the study. Male gender (AOR = 2.71; 95% CI: 1.63-4.50), spending overnight in forest (AOR = 1.92; 95% CI: 1.20-3.06), not using mosquito repellent (AOR = 2.49; 95% CI: 1.36-4.56) and history of previous malaria infection (AOR = 49.34; 95% CI: 39.09-78.32) were found to be independent predictors of P. knowlesi infection.

CONCLUSIONS

This study showed the need to strengthen the strategies in preventing and controlling P. knowlesi infection specifically in changing the practice of spending overnight in forest and increasing the usage of personal mosquito repellent.

Proposed Integrated Control of Zoonotic Plasmodium knowlesi in Southeast Asia Using Themes of One Health

Zoonotic malaria, Plasmodium knowlesi, threatens the global progression of malaria elimination. Southeast Asian regions are fronting increased zoonotic malaria rates despite the control measures currently implemented-conventional measures to control human-malaria neglect P. knowlesi's residual transmission between the natural macaque host and vector. Initiatives to control P. knowlesi should adopt themes of the One Health approach, which details that the management of an infectious disease agent should be scrutinized at the human-animal-ecosystem interface. This review describes factors that have conceivably permitted the emergence and increased transmission rates of P. knowlesi to humans, from the understanding of genetic exchange events between subpopulations of P. knowlesi to the downstream effects of environmental disruption and simian and vector behavioral adaptations. These factors are considered to advise an integrative control strategy that aligns with the One Health approach. It is proposed that surveillance systems address the geographical distribution and transmission clusters of P. knowlesi and enforce ecological regulations that limit forest conversion and promote ecosystem regeneration. Furthermore, combining individual protective measures, mosquito-based feeding trapping tools and biocontrol strategies in synergy with current control methods may reduce mosquito population density or transmission capacity.

The Effect of Body Composition and Energy Expenditure on Permethrin Biomarker Concentrations Among US Army National Guard Members

OBJECTIVE

To examine relationships between percent body fat (%BF) and total energy expenditure (TEE) on permethrin exposure among Army National Guard (ARNG) Soldiers wearing permethrin-treated uniforms.

METHODS

ARNG members (n = 47) participated in a 9-day study. Repeated body composition (height, weight, %BF) measurements and daily urine samples, analyzed for permethrin and N,N-diethyl-meta-toluamide (DEET) metabolites, were collected. TEE was determined via doubly labeled water protocol. Linear mixed and regression models were used for analyses.

RESULTS

Neither %BF nor TEE were significantly associated with permethrin or DEET biomarkers. However, a significant interaction effect (F = 10.76; P = 0.0027) between laundering history and %BF was observed; 10% higher %BF was significantly associated with 25% higher permethrin biomarker concentrations among those wearing uniforms washed less than or equal to 25 (compared with more than 25) times.

CONCLUSIONS

Uniform laundering history significantly affects the association between %BF and permethrin-treated uniform exposure.