Murine typhus, caused by Rickettsia typhi, is re-emerging in many parts of the world. The disease is also called endemic typhus to differentiate from epidemic typhus (caused by Rickettsia prowazekii), and sometimes also named flea-borne typhus. Occasionally, literature sources will include Rickettsia felis as a causative agent of flea-borne typhus, but illnesses caused by R. felis are actually flea-borne spotted fever. Murine typhus occurs in warm, coastal areas worldwide. In the United States, most cases are reported from California, Texas, and Hawaii. Murine typhus is usually a self-limited febrile illness but about one-quarter of patients suffer organ complications. The disease is only infrequently fatal. Regarding disease ecology, the historical paradigm is that rats (Rattus rattus and R. norvegicus) are reservoirs of R. typhi worldwide, with rat fleas (Xenopsylla cheopis) as primary vectors. More recently, researchers have proposed an alternative suburban murine typhus transmission cycle involving opossums, cat fleas, cats, and dogs in Texas, California, and rural Mexico. Because cat fleas feed on a variety of mammals, there may be other avenues for R. typhi transmission, including stray or feral cats bringing cat fleas and other infected fleas into proximity with humans and possible aerosolization of infected flea feces. Additional fleas, ticks, lice, and mites may play a role in various areas throughout the world, but a striking lack of fundamental research on this topic makes drawing conclusions difficult. This review provides an overview of the history, epidemiology, diagnosis, and treatment of murine typhus, with special emphasis on its disease ecology.

Ticks and tick-borne diseases are of increasing concern in the United States, and understanding tick behavior could be crucial to limiting the exposure of humans and other animals to ticks. Here, we wanted to understand the drivers of questing and burrowing in Amblyomma americanum and A. maculatum. We used a factorial design to assess the effects of substrate (sand, soil, and rock), temperature (16° and 22° C), tick species (A. maculatum and A. americanum), and competition (homogenous or heterogenous mixture of ticks in the arena) on tick behavior in laboratory arenas. Questing varied significantly between tick species, with 61% of A. americanum questing compared to 35% of A. maculatum. Substrate similarly affected questing, with most ticks questing in the arenas with sand (83%) compared to arenas with rock (35%) or soil (25%). Burrowing behavior was also influenced by substrate; every tick in the arenas with rock (100%) and nearly all in the arenas with soil (98%) exhibited burrowing, whereas only 10% burrowed in sand. A. americanum traveled longer distances than A. maculatum (23 ± 2.8 cm vs 9.7 ± 2.3 cm). The disparity in laboratory behavior between sand and rock/soil substrates might warrant further consideration in a field setting, as understanding factors that inhibit host-seeking behaviors of ticks can inform management of public spaces and potentially help mitigate tick-exposure.

Musca domestica salivary gland hypertrophy virus (MdSGHV) affects house flies by enlarging salivary glands, impeding ovary development in females, and mating behavior in both males and females. It is not known if this virus impacts the quantity of saliva produced by house flies. This study aimed to establish baseline saliva quantities in healthy M. domestica across sexes and ages and examine how MdSGHV infection influences saliva output in 5-day-old males. Results reveal that healthy female Musca domestica produce more saliva on average than males and that saliva production among both sexes decreases with age. A comparison of infected, PBS-injected, and healthy flies shows significantly higher saliva quantities in infected individuals, suggesting MdSGHV enhances saliva production to improve transmission. These findings provide insights into MdSGHV transmission dynamics, which may provide for a better understanding of how other vector-borne diseases like Zika and Dengue virus interact in the infected salivary glands of the host vector.

Human cases of arboviral disease transmitted by Aedes mosquitoes are increasing worldwide and spreading to new areas of the United States. These diseases continue to re-emerge, likely due to changes in vector ecology, urbanization, human migration, and larger range of climatic suitability. Recent shifts in landscape and weather variables are predicted to impact the habitat patterns of urban mosquitoes such as Aedes aegypti and Aedes albopictus. Miami, FL is in the tropical zone, while Charleston, SC is in the humid subtropical zone, and both cities are established hotspots for arboviruses. We applied remote sensing with land-use cover and weather variation to identify mosquito infestation patterns. We detected statistically significant positive and negative associations between entomological indicators and most weather variables in combined data from both cities. For all entomological indices, weekly wind speed and relative humidity were significantly positively associated, while precipitation and maximum temperature were significantly negatively associated. Aedes egg abundance was significantly positively associated with open land in Charleston but was negatively associated with vegetation cover in combined data.

This study examined the presence and characteristics of microplastics (MPs) in water collected from potential mosquito oviposition habitats in Lubbock, TX. Water samples ranging from 10 to 1000 mL were collected from 36 suspected artificial and natural oviposition habitats, and sites were categorized as artificial containers, tires, or natural sites. Samples were filtered through a series of stainless-steel sieves and isopore membrane filters, and MPs were imaged and counted using a stereo microscope. MPs were classified by shape into fragments, fibers, films, spheres, and foams. Scanning Electron Microscopy (SEM), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA)were employed to characterize the size, morphology, and polymer type of MPs collected from a subset of oviposition habitats. Results suggest MPs are commonly found in artificial containers and tires, and at higher concentrations than natural sites. Furthermore, MPs found in all potential oviposition sites were predominantly fragments and fibers. SEM analysis revealed diverse morphologies and indicated potential microbial colonization on MP surfaces. Ultimately, this study provides insights into the distribution and characteristics of MPs in mosquito oviposition habitats, highlighting the potential impact of MP pollution and the potential effects on mosquito biology, and serves as a foundation for further research on the ecological implications of MPs in mosquito oviposition habitats.

We investigated the abundance and distribution of Aedes aegypti and Aedes albopictus mosquitoes in urban parks in the eastern zone of the city of São Paulo, where the highest number of autochthonous dengue cases during the major 2015-2016 epidemic was reported. The association of climatic and environmental factors with the spatiotemporal distribution of species in relation to vegetation cover and human proximity was examined. Twelve geo-referenced ovitraps were randomly installed in each park, covering areas with varying degrees of vegetation and human activity from September, 2018 to February, 2020, during three weeks each season. A total of 57,604 Aedes aegypti or Aedes albopictus eggs were collected, identifying 10,228 Ae. aegypti and 23,764 Ae. albopictus larvae. Seasonal variations showed distinct patterns with higher mosquito abundances during warmer and rainier seasons. The association between abundance and climatic factors was more evident at the level of the aedini assemblies than at the level of the local populations. Aedes aegypti was predominantly found in peripheral and transitional areas with higher human activity during rainy and warmer seasons. In contrast, Ae. albopictus thrived in inner park areas with greater vegetation cover and lower human activity during drier and milder seasons. The abundance of Ae. aegypti and Ae. albopictus was influenced by climatic factors and park-specific microhabitats. These findings underscore the importance of targeted vector control strategies in urban park settings during seasons favorable for mosquito reproduction. Understanding the interaction between ecological factors and these mosquitoes in urban environments is critical for effective public health interventions.

The CDC light trap with incandescent light is the most commonly used method for conducting sand fly surveillance. However, new trap models that use LED lights might provide a more cost-effective alternative. This study compared the efficacy of a modified commercial Katchy light trap with two CDC light trap models in capturing sand flies in the Amazonian rainforest of Peru. Using a 3 x 3 randomized Latin square design, the light traps were compared based on phlebotomine sand fly species total abundance, species richness, sex-specific collections, and efficiency in capturing potential vector species. A total of 1,184 sand flies were collected, representing nine genera and 25 species, including three species that had not been previously reported in the Cusco department. Significant differences in sand fly collections based on trap type were found, with the modified Katchy light trap capturing significantly higher total abundance and species richness compared to CDC light traps. This pattern held for both female and male sand flies, with the modified Katchy trap also collecting more potential vector species in terms of both abundance and species richness, although differences in potential vector species richness were only significant compared to the incandescent CDC light trap. These results suggest that the modified Katchy trap is a viable, cost-effective alternative for sand fly surveillance, offering potential improvements in leishmaniasis vector monitoring.

This field study describes the abundance of ticks and the prevalence of tick-borne pathogens in two hiking areas, Stebbins Cold Canyon (SCC) and Skyline Wilderness Park (SKY), in northern California. These areas have experienced extreme weather events, including wildfire, drought, and heavy rainfall, which have changed the environment. Questing ticks were collected over nine months, identified to species, and screened for tick-borne pathogens using qPCR. Four hundred and fifty-nine ticks were collected, including 54 adults from SCC and 405 from SKY, consisting of 279 (68.9%) larvae, 2 (0.5%) nymphs, and 124 (30.6%) adults. At SCC, Ixodes pacificus and Dermacentor occidentalis accounted for 92.6% (50/54) and 7.4% (4/54), respectively. At SKY, I. pacificus (16.8%, 68/405), D. occidentalis (12.3%, 50/405), D. similis (0.7%, 3/405), and D. albipictus (70.4%, 285/405) were collected. Overall, the prevalence of tick-borne pathogens was low in the collected ticks. Borrelia burgdorferi sl (0.8%, 1/121) and Rickettsia rhipicephali (1.7%, 2/121) were found at SKY. Rickettsia tillamookensis was identified at SCC and SKY with a prevalence of 3.7% (2/54) and 1.7% (2/121), respectively. Babesia duncani was identified in 3.7% (2/54) and 1.2% (5/405) of ticks at SCC and SKY, respectively. These findings suggest that multiple tick species can withstand extreme weather events, providing further data regarding the effects of weather extremes and climate change on tick populations and pathogen prevalence. This study is one of the first to report B. duncani in I. pacificus ticks in California, particularly in Solano County.