Dog ectoparasites as sentinels for pathogenic Rickettsia and Bartonella in rural Guatemala.

Fleas and ticks serve as vectors of multiple pathogens in the genera Rickettsia and Bartonella that cause diseases in humans and other animals. Although human rickettsiosis and bartonellosis have been reported in all countries in Central America, limited research has been conducted to investigate the natural cycles of flea- and tick-borne rickettsiosis and bartonellosis, especially in Guatemala. We evaluated dog parasites as sentinels for zoonotic disease risk in rural Guatemala by sampling ticks and fleas from dogs, which were then identified and individually screened for Rickettsia and Bartonella. A total of 77 households were surveyed and 80.5 % of them had dogs. Overall, 133 dogs were examined for fleas and ticks, of which 68.4 % had fleas and 35.3 % had ticks. A total of 433 fleas and 181 ticks were collected from the infested dogs, with an additional 33 ticks collected from house walls. Three flea species were identified: Ctenocephalides felis (70.0 %), Echidnophaga gallinacea (11.8 %), and Pulex sp. (17.8 %). Among the collected ticks, 97 % were identified as Rhipicephalus sanguineus sensu lato with the rest being Amblyomma cajennense, A. auricularium, and A. ovale. Rickettsia felis were detected in six C. felis, in one Pulex sp., and in two R. sanguineus sensu lato, while Candidatus R. senegalensis was detected in one C. felis. Bartonella was detected only in fleas, including three Pulex sp. infected with B. vinsonii subsp. berkhoffii, B. henselae, and Bartonella sp., respectively, and 11 C. felis infected with B. henselae. This study reports Candidatus R. senegalensis and B. vinsonii subsp. berkhoffii in Guatemala for the first time, and indicates the potential risk of human and dog exposure to Rickettsia and Bartonella species. These results show that dogs provide critical information relevant to managing human potential exposure to flea- and tick-borne pathogens in rural Guatemala. This approach can potentially be expanded to other regions in Central America where domestic dogs are abundant and suffer from ectoparasite infestation.

Climate change and Trypanosoma cruzi transmission in North and central America.

Trypanosoma cruzi is a protozoan parasite that causes Chagas disease in humans. Transmission of T cruzi by triatomine vectors is dependent on diverse environmental and socioeconomic factors. Climate change, which is disrupting patterns of human habitation and land use, can affect the epidemiology of Chagas disease by influencing the distribution of vector and host species. We conducted a review using triatomine distribution as a proxy for T cruzi transmission in North America (Canada, Mexico, and the USA) and central America (Belize, Costa Rica, El Salvador, Guatemala, Honduras, Nicaragua, and Panama) and investigated the association of T cruzi transmission with climate change, identifying 12 relevant studies. Most studies (n=9) modelled the effect of the scenario of climate change on the distribution of relevant vector species and found that global warming could sometimes favour and sometimes hinder triatomine distribution. There is a need for more research in parasite biology and social sciences to further understand how climate change and socioeconomic factors can affect the epidemiology of this neglected tropical disease.

On-host flea phenology and flea-borne pathogen surveillance among mammalian wildlife of the pineywoods of East Texas.

Flea-borne diseases are endemic in Texas, U.S.A., with an increasing incidence of flea-borne typhus and cat scratch disease. Knowledge of flea natural history could provide information to protect public health, yet many knowledge gaps remain outside of plague-endemic regions. Our objective was to characterize seasonal activity patterns of fleas on common mammalian wildlife species and test fleas and wildlife for Rickettsia and Bartonella pathogens. We performed one year of monthly trapping for rodents and medium-sized mammals in a national forest with high recreational use and urban encroachment in East Texas. From 90 mammal captures representing seven species, 101 fleas were collected representing Polygenis spp., Ctenocephalides felis, and Orchopeas species. Virginia opossums (Didelphis virginianus) hosted 99% of the collected fleas (100 fleas) and a single flea was on an eastern woodrat (Neotoma floridana). Flea infestation prevalence of opossums was 79% (23/29). Mean flea abundance was 4.39 fleas, with intensity peaking in spring. One cat flea removed from an opossum was positive for Bartonella henselae. Furthermore, we identified tissue or blood of four raccoons (Procyon lotor) and one golden mouse (Ochrotomys nuttalli) positive for Rickettsia amblyommatis. These findings provide an ecological basis for the maintenance of vectors and pathogens from sylvatic settings.

Dog ectoparasites as sentinels for pathogenic Rickettsia and Bartonella in rural Guatemala.

Background: Fleas and ticks serve as vectors of multiple pathogens in the genera Rickettsia and Bartonellathat cause diseases in humans and other animals. Although human rickettsiosis and bartonellosis have been reported in all countries in Central America, limited research has been conducted to investigate the natural cycles of flea- and tick-borne rickettsiosis and bartonellosis, especially in Guatemala. Methods: We evaluated dog parasites as sentinels for zoonotic disease risk in rural Guatemala by sampling ticks and fleas from dogs, which were then identified and individually screened for Rickettsia and Bartonella. Results: A total of 77 households were surveyed and 80.52% of them had dogs. Overall, 133 dogs were examined for fleas and ticks, of which 68.42% had fleas and 35.34% had ticks. A total of 433 fleas and 181 ticks were collected from the infested dogs, with an additional 33 ticks collected from house walls. Three flea species were identified: Ctenocephalides felis (70%), Echidnophaga gallinacea(11.8%), and Pulex sp. (17.8%). Among the collected ticks, 97% were Rhipicephalus sanguineus with the rest being Amyblyomma cajennense, A. auricularium, and A. ovale. Rickettsia felis were detected in six C. felis, in one Pulex sp., and in two R. sanguineus, while Candidatus R. senegalensis was detected in one C. felis. Bartonella was detected only in fleas, including three Pulexsp. infected with B. vinsonii subsp. Berkhoffii, B. henselae, and Bartonella sp., respectively, and 11 C. felis infected with B. henselae. Conclusions: This study reports Candidatus R. senegalensis and B. vinsonii subsp. Berkhoffiiin Guatemala for the first time, and indicates the potential risk of human and dog exposure to Rickettsia and Bartonella species. These results show that dogs provide critical information relevant to managing human potential exposure to flea- and tick-borne pathogens in rural Guatemala.

Effectiveness of mass trapping interventions using autocidal gravid ovitraps (AGO) for the control of the dengue vector, Aedes (Stegomyia) aegypti, in Northern Mexico.

BACKGROUND: Mosquito-borne diseases, such as malaria, dengue, Zika and chikungunya, pose significant public health threats in tropical and subtropical regions worldwide. To mitigate the impact of these diseases on human health, effective vector surveillance and control strategies are necessary. Traditional vector control methods, which rely on chemical agents such as insecticides and larvicides, face challenges such as resistance and environmental concerns. Consequently, there has been a push to explore novel surveillance and control tools. Mass trapping interventions have emerged as a promising and environmentally friendly approach to reducing the burden of mosquito-borne diseases. This study assessed mass-trapping interventions using autocidal gravid ovitraps (AGOs) on Aedes aegypti populations in Reynosa, Tamaulipas, Mexico. METHODS: Four neighborhoods were selected to evaluate the effects of three treatments: AGO mass-trapping, integrated vector control (IVC), which included source reduction and the application of chemical larvicide and adulticide, and AGO + IVC on Ae. aegypti populations. A control area with no interventions was also included. The effectiveness of the interventions was evaluated by comparing Ae. aegypti abundance between the pre-treatment period (9 weeks) and the post-treatment period (11 weeks) for each treatment. RESULTS: Only treatment using AGO mass trapping with an 84% coverage significantly reduced Ae. aegypti female populations by 47%, from 3.75 ± 0.32 to 1.96 ± 0.15 females/trap/week. As expected, the abundance of Ae. aegypti in the control area did not differ from the pre- and post-treatment period (range of 4.97 ± 0.59 to 5.78 ± 0.53); Ae. aegypti abundance in the IVC treatment was 3.47 ± 0.30 before and 4.13 ± 0.35 after, which was not significantly different. However, Ae. aegypti abundance in the AGO + IVC treatment increased from 1.43 ± 0.21 before to 2.11 ± 0.20 after interventions; this increase may be explained in part by the low AGO (56%) coverage. CONCLUSIONS: This is the first report to our knowledge on the effectiveness of mass-trapping interventions with AGOs in Mexico, establishing AGOs as a potential tool for controlling Ae. aegypti in Northeastern Mexico when deployed with sufficient coverage.

Development of an operational trap for collection, killing, and preservation of triatomines (Hemiptera: Reduviidae): the kissing bug kill trap.

Surveillance of triatomines or kissing bugs (Hemiptera: Reduviidae: Triatominae), the insect vectors of Trypanosoma cruzi, a Chagas disease agent, is hindered by the lack of an effective trap. To develop a kissing bug trap, we made iterative improvements over 3 years on a basic design resulting in 7 trap prototypes deployed across field sites in Texas, United States and Northern Mexico, yielding the capture of 325 triatomines of 4 species (Triatoma gerstaeckeri [Stål], T. sanguisuga [LeConte], T. neotomae [Neiva], and T. rubida [Uhler]). We began in 2019 with vertical transparent tarpaulin panel traps illuminated with artificial light powered by AC current, which were successful in autonomous trapping of flying triatomines, but were expensive, labor-intensive, and fragile. In 2020, we switched to white LED lights powered by a solar cell. We tested a scaled-down version of the vertical panel traps, a commercial cross-vane trap, and a multiple-funnel trap. The multiple-funnel traps captured 2.6× more kissing bugs per trap-day than cross-vane traps and approached the performance of the vertical panel traps in number of triatomines captured, number of triatomines per trap-day and triatomines per arthropod bycatch. Multiple-funnel traps required the least labor, were more durable, and had the highest triatomines per day per cost. Propylene glycol in the collection cups effectively preserved captured triatomines allowing for molecular detection of T. cruzi. The trapping experiments established dispersal patterns for the captured species. We conclude that multiple-funnel traps with solar-powered LED lights should be considered for adoption as surveillance and potentially mass-trapping management tools for triatomines.

Domestic Dog Infection with Trypanosoma cruzi from Northern and Southern Regions of Mexico.

Background: Chagas disease or American trypanosomiasis, caused by Trypanosoma cruzi and vectored by triatomines, affects millions of people worldwide. In endemic countries including Mexico, infections in domestic animals, such as dogs, may affect the risk of human disease when they serve as a source of infection to vectors that subsequently infect humans. Materials and Methods: We conducted a cross-sectional study of 296 dogs from two cities near the northern and southern borders of Mexico: Reynosa, Tamaulipas, and Tuxtla Gutierrez, Chiapas. Infection was measured based on testing of blood using T. cruzi quantitative PCR (qPCR) and up to three antibody detection assays. The StatPak immunochromatographic assay was used to screen samples and the indirect fluorescent antibody (IFA) and multiplex microsphere immunoassay (MIA) tests were used as secondary tests on all samples that screened positive and a subset of negatives. Serologic positivity was defined based on reactivity on at least two independent tests. Results: Of the 280 samples tested for parasite DNA, two (0.7%) were positive, one of which (0.4%) was confirmed as T. cruzi discrete typing unit TcIV. Overall, 72 (24.3%) samples were reactive for T. cruzi antibodies via StatPak of which 8 were also positive using MIA and 2 were also positive using IFA (including one of the PCR-positive dogs). Overall, nine dogs (3.4%) met study criteria of positivity based on either/both serology or PCR tests. Positive dogs were found in both regions of Mexico; five (2.7%) from Reynosa and four (3.6%) from Tuxtla Gutierrez. We found no association between infection status and state of origin, sex, age group, breed group, neighborhood, and whether other pets lived in the home. Conclusion: Our results re-emphasize dogs' utility as sentinels for T. cruzi in Mexico and underscore the need for improved veterinary diagnostic tests and parasite surveillance at the household level in endemic countries.

Trapped between food, heat, and insects: Movement of moose (Alces alces) and exposure to flies in the boreal forest of Alaska.

Moose (Alces alces) in the boreal forest habitats of Alaska are unlike other northern ungulates because they tolerate high densities of flies (Diptera) even though flies cause wounds and infections during the warm summer months. Moose move to find food and to find relief from overheating (hyperthermia) but do they avoid flies? We used GPS collars to measure the rate of movement (m⋅h-1) and the time spent (min⋅day-1) by enclosed moose in four habitats: wetlands, black spruce, early seral boreal forest, and late seral boreal forest. Fly traps were used in each habitat to quantify spatio-temporal abundance. Average daily air temperatures increased into July when peak biomass of forage for moose was greatest in early seral boreal forest habitats (424.46 vs. 25.15 kg⋅ha-1 on average in the other habitats). Average daily air temperatures were 1.7°C cooler in black spruce than other habitats, but fly abundance was greatest in black spruce (approximately 4-fold greater on average than the other habitats). Moose increased their movement rate with counts of biting flies (mosquitoes, black flies, horse and deer flies), but not non-biting flies (coprophagous flies). However, as air temperature increased (above 14.7°C) moose spent more time in fly-abundant black spruce, than early seral boreal forest, showing great tolerance for mosquitoes. Warm summer temperatures appear to cause moose to trade-off foraging in fly-sparse habitats for resting and dissipating heat in shady, wet habitats with abundant flies that adversely affect the fitness of moose.

Uncertainties Surrounding Madariaga Virus, a Member of the Eastern Equine Encephalitis Virus Complex.

Background: Madariaga virus (MADV), a member of the eastern equine encephalitis virus (EEEV) complex, circulates in Latin America and exhibits distinct evolutionary and ecological features compared to the North American EEEV. While published data have shed light on MADV ecology, several key aspects remain unknown. Methods: In this study, we compiled data on virus isolation, vector competence, and animal serology collected over six decades in Latin America to identify critical knowledge gaps on MADV transmission and ecology. Results: Specific vertebrate animals serving as amplifying hosts and the mosquito species acting as enzootic and epizootic vectors have not yet been identified. Other aspects that remain unclear are the virus current geographic distribution, the role of equines as hosts in epizootic cycles, and the full impact of MADV on human health in endemic regions. Conclusions: The numerous knowledge gaps surrounding MADV, its widespread distribution in Latin America, and its potential to cause severe disease in animals and humans emphasize the urgent need for increased research efforts, heightened awareness, and intensified surveillance towards this potential emerging threat.

A pilot community science program in Mexico for passive triatomine surveillance and increase Chagas disease awareness / Programa piloto de ciencia ciudadana en México para vigilancia pasiva de triatominos y concientizar sobre la enfermedad de Chagas

Objective. To generate data about Chagas disease vectors through passive surveillance and inform the public using social media and community science. Materials and methods. We used social media to inform, raise awareness and to promote the public to report their triatomine encounters. We received pictures and specimens collected to be tested for Trypanosoma cruzi and to identify recent bloodmeal source through PCR. Results. Community scientists reported 44 triatomines from 15 states in Mexico and one triatomine from Nicaragua, including 9 species with Triatoma dimidiata sensu lato and T. gerstaeckeri being the most common. We received 12 collected specimens and T. cruzi was detected in 8 (67%) of the discrete typing unit TcI. We identified recent bloodmeal source in 6 triatomines including: human (Homo sapiens), dog (Canis lupus familiaris), wood rat (Neotoma sp.), dove (Columbidae) and amphibius (Bufonidae). Conclusion. The use of community science can be a complementary method to generate information about the ecology and epidemiology of Chagas disease vectors.

Objetivo. Generar datos sobre vectores de la enfermedad de Chagas (EC) mediante vigilancia pasiva e informar a la población mediante redes sociales y ciencia ciudadana. Material y métodos. Utilizando redes sociales informamos, concientizamos y alentamos al público a reportarnos sus encuentros con triatominos. Recibimos reportes fotográficos y especímenes colectados a los que analizamos para detectar infección por Trypanosoma cruzi e identificar la fuente reciente de alimentación mediante PCR. Resultados. Nos reportaron 44 triatominos de 15 estados en México y uno de Nicaragua, incluyendo 9 especies siendo Triatoma dimidiata sensu lato y T. gerstaeckeri las más comunes. Recibimos 12 especímenes colectados y encontramos T. cruzi en 8 (67%) de la unidad taxonómica discreta TcI. Identificamos fuente reciente de alimentación en 6 triatominos incluyendo: humano (Homo sapiens), perro (Canis lupus familiaris), rata de campo (Neotoma sp.), paloma (Columbidae) y anfibio (Bufonidae). Conclusión. Ciencia ciudadana puede ser un método complementario para generar información sobre ecología y epidemiología de EC.