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Chikungunya virus (CHIKV) was isolated from humans in an outbreak of a febrile illness during July and August 2015 in the central valleys of Chiapas, Mexico. Sera obtained from 80 patients were tested for CHIKV RNA by reverse transcriptase polymerase chain reaction (RT-PCR) and for IgM and IgG antibodies by an enzyme linked immunoassay and a commercial indirect immunofluorescence test for CHIKV and dengue virus (DENV). Of the 80 patients, 67 were positive, including 50 for RNA and 17 for IgM. In addition, one patient was coinfected with CHIKV-DENV and 40 patients were positive for IgG antibody to DENV. The clinical manifestations included a high fever, polyarthralgia, headache, myalgia, rash, digestive disorders, conjunctivitis, and adenopathy associated with cervical and axillary inguinal regions. Complete nucleotide sequences of two of the CHIKV isolates showed that they belonged to the Asian lineage but did not group with other Mexican CHIKV isolates from the Chiapas coast. Our findings documented that different Asian lineage strains of CHIKV were circulating simultaneously during the 2015 outbreak in the Central Valley of Chiapas, Mexico. The 2024 cases suggest an explosive scenario of re-emergence of thousands of new Chikungunya and dengue fever (DENF) cases associated with deaths, and a dangerous increase of the four DENV serotypes throughout the Americas, especially in South American countries that have shown a high influx of human migration to southern Mexico. In Mexico, the state of Chiapas and other southern regions are the most vulnerable., Competing Interests: Conflicts of Interest The authors declare no conflict of interest.

We report the 1st records of Aedes tormentor and Culex panocossa throughout vector surveillance events carried out in putative foci of eastern equine encephalitis in Tamaulipas, Mexico. Formerly, Ae. tormentor had been reported in, at least, 2 Central American countries and Mexico. In Mexico, reports were from the states of Campeche, Chiapas, Quintana Roo, and Veracruz. Records of Ae. tormentor in these 4 Neotropical states were recently reviewed and eliminated; thus, the southernmost geographic distribution for this species is considered to be the state of Tamaulipas Mexico in its neotropical zone. Further, Cx. panocossa had been collected in Guerrero, Tabasco, and Veracruz. In Tamaulipas, there are 82 species of mosquitoes, being the 4th state accounting for the highest mosquito species diversity of 11 states in which comprehensive studies have been conducted on the subject of mosquito distribution., (Copyright © 2024 by The American Mosquito Control Association, Inc.)

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., (© 2024. The Author(s).)

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.

Aedes albopictus is a vector of several pathogens of significant public health concern. In this situation, gravid traps have become a common surveillance tool for Aedes spp., which commonly use hay infusions as an attractant. Diverse grass infusions have been assessed to enhance the attraction to this vector mosquito. However, these studies have focused on the oviposition effect, and the attraction potential to gravid Ae. albopictus females has not been evaluated yet. Here we report the attractiveness of infusions of 4 different botanical species (Cenchrus purpureus, Cyanodon dactylon, Megathyrus maximus, Pennisetum ciliare) as baits in sticky ovitraps and autocidal gravid ovitraps (AGOs) under laboratory, semifield, and field conditions. In the laboratory, Cynodon dactylon showed attractiveness, whereas in semifield conditions, both C. dactylon and Megathyrsus maximus were similarly attractive for gravid Ae. albopictus. None of the infusions conducted with AGOs were able to lure Ae. albopictus and other species of mosquitoes in a 14-wk field experiment. Our results demonstrate the feasibility of finding more attractive infusions for Ae. albopictus females to improve the efficacy of AGO traps, but further testing of infusions in AGOs in field settings is needed., (Copyright © 2024 by The American Mosquito Control Association, Inc.)

We found serologic evidence of spotted fever group Rickettsia in humans and dogs and typhus group Rickettsia in dogs in Reynosa, Mexico. Our investigation revealed serologic samples reactive to spotted fever group Rickettsia in 5 community members, which highlights a potential rickettsial transmission scenario in this region.

SARS-CoV-2 mainly affects humans; however, it is important to monitor the infection of companion and wild animals as possible reservoirs of this virus. In this sense, seroprevalence studies in companion animals, such as dogs and cats, provide important information about the epidemiology of SARS-CoV-2. This study aimed to evaluate the seroprevalence of neutralizing antibodies (nAbs) against the ancestral strain and the Omicron BA.1 subvariant in dogs and cats in Mexico. Six hundred and two samples were obtained from dogs (n = 574) and cats (n = 28). These samples were collected from the end of 2020 to December 2021 from different regions of Mexico. The presence of nAbs was evaluated using a plaque reduction neutralization test (PRNT) and microneutralization (MN) assays. The results showed that 14.2% of cats and 1.5% of dogs presented nAbs against the ancestral strain of SARS-CoV-2. The analysis of nAbs against Omicron BA.1 in cats showed the same percentage of positive animals but a reduced titer. In dogs, 1.2% showed nAbs against Omicron BA.1. These results indicate that nAbs were more frequent in cats than in dogs and that these nAbs have a lower capacity to neutralize the subvariant Omicron BA.1.

Here, we report three near-full-length genome sequences of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) obtained in Mexico City, Mexico, during the pandemic of coronavirus disease 19 (COVID-19) in 2020, representing a zooanthroponotic transmission event between humans and a dog. All three genomes belong to the B.1.189 lineage based on the pangolin classification.

Of the documented tick-borne diseases infecting humans in México, Rocky Mountain spotted fever (RMSF), caused by the Gram-negative bacterium Rickettsia rickettsii , is responsible for most fatalities. Given recent evidence of brown dog tick, Rhipicephalus sanguineus s.l., as an emerging vector of human RMSF, we aimed to evaluate dogs and their ticks for rickettsiae infections as an initial step in assessing the establishment of this pathosystem in a poorly studied region of northeastern México while evaluating the use of dogs as sentinels for transmission/human disease risk. We sampled owned dogs living in six disadvantaged neighborhoods of Reynosa, northeastern México to collect whole blood and ticks. Of 168 dogs assessed, tick infestation prevalence was 53%, composed of exclusively Rh. sanguineus s. l. ( n = 2170 ticks). Using PCR and sequencing, we identified an overall rickettsiae infection prevalence of 4.1% ( n = 12/292) in ticks, in which eight dogs harbored at least one infected tick. Rickettsiae infections included Rickettsia amblyommatis and Rickettsia parkeri , both of which are emerging human pathogens, as well as Candidatus Rickettsia andeanae. This is the first documentation of pathogenic Rickettsia species in Rh. sanguineus s.l. collected from dogs from northeastern México. Domestic dog infestation with Rickettsia -infected ticks indicates ongoing transmission; thus, humans are at risk for exposure, and this underscores the importance of public and veterinary health surveillance for these pathogens.

We tested 294 domestic pet dogs in Mexico for neutralizing antibodies for mosquito-borne flaviviruses. We found high (42.6%) exposure to West Nile virus in Reynosa (northern Mexico) and low (1.2%) exposure in Tuxtla Gutierrez (southern Mexico) but very limited exposure to Aedes-borne flaviviruses. Domestic dogs may be useful sentinels for West Nile virus.

Background: Aedes aegypti mosquito-borne viruses including Zika (ZIKV), dengue (DENV), yellow fever (YFV), and chikungunya (CHIKV) have emerged and re-emerged globally, resulting in an elevated burden of human disease. Aedes aegypti is found worldwide in tropical, sub-tropical, and temperate areas. The characterization of mosquito blood meals is essential to understand the transmission dynamics of mosquito-vectored pathogens., Methodology/principal Findings: Here, we report Ae. aegypti and Culex quinquefasciatus host feeding patterns and arbovirus transmission in Northern Mexico using a metabarcoding-like approach with next-generation deep sequencing technology. A total of 145 Ae. aegypti yielded a blood meal analysis result with 107 (73.8%) for a single vertebrate species and 38 (26.2%) for two or more. Among the single host blood meals for Ae. aegypti, 28.0% were from humans, 54.2% from dogs, 16.8% from cats, and 1.0% from tortoises. Among those with more than one species present, 65.9% were from humans and dogs. For Cx. quinquefasciatus, 388 individuals yielded information with 326 (84%) being from a single host and 63 (16.2%) being from two or more hosts. Of the single species blood meals, 77.9% were from dogs, 6.1% from chickens, 3.1% from house sparrows, 2.4% from humans, while the remaining 10.5% derived from other 12 host species. Among those which had fed on more than one species, 11% were from dogs and humans, and 89% of other host species combinations. Forage ratio analysis revealed dog as the most over-utilized host by Ae. aegypti (= 4.3) and Cx. quinquefasciatus (= 5.6) and the human blood index at 39% and 4%, respectively. A total of 2,941 host-seeking female Ae. aegypti and 3,536 Cx. quinquefasciatus mosquitoes were collected in the surveyed area. Of these, 118 Ae. aegypti pools and 37 Cx. quinquefasciatus pools were screened for seven arboviruses (ZIKV, DENV 1-4, CHIKV, and West Nile virus (WNV)) using qRT-PCR and none were positive (point prevalence = 0%). The 95%-exact upper limit confidence interval was 0.07% and 0.17% for Ae. aegypti and Cx. quinquefasciatus, respectively., Conclusions/significance: The low human blood feeding rate in Ae. aegypti, high rate of feeding on mammals by Cx. quinquefasciatus, and the potential risk to transmission dynamics of arboviruses in highly urbanized areas of Northern Mexico is discussed., Competing Interests: The authors have declared that no competing interests exist.

The ongoing Coronavirus Disease 2019 (COVID-19) pandemic threatens the health of humans and causes great economic losses. Predictive modeling and forecasting the epidemic trends are essential for developing countermeasures to mitigate this pandemic. We develop a network model, where each node represents an individual and the edges represent contacts between individuals where the infection can spread. The individuals are classified based on the number of contacts they have each day (their node degrees) and their infection status. The transmission network model was respectively fitted to the reported data for the COVID-19 epidemic in Wuhan (China), Toronto (Canada), and the Italian Republic using a Markov Chain Monte Carlo (MCMC) optimization algorithm. Our model fits all three regions well with narrow confidence intervals and could be adapted to simulate other megacities or regions. The model projections on the role of containment strategies can help inform public health authorities to plan control measures., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Inc. All rights reserved.)

During ecological investigations for arboviruses conducted in coastal Chiapas, Mexico, in 2007, isolate MP1078 was obtained from a pool of Psorophora varipes mosquitoes. Based on antigenic characterization, this isolate was classified as a strain of Patois virus (PATV) ( Orthobunyavirus genus, Peribunyaviridae family). Recently, we conducted nearly complete genome sequencing of this isolate to gain further insight into its genetic relationship with other members of the Patois serogroup. Based on the genetic characterization, we determined that MP1078 contains S, M, and L genome segments that are genetically distinct from other viruses within the Patois serogroup. Serological analyses confirmed the taxonomic classification of MP1078 as a new virus and species within the Patois serogroup, and we propose the name Barrita virus (BITV).

Mosquito-borne viruses are emerging or re-emerging globally, afflicting millions of people around the world. Aedes aegypti , the yellow fever mosquito, is the principal vector of dengue, Zika, and chikungunya viruses, and has well-established populations across tropical and subtropical urban areas of the Americas, including the southern United States. While intense arboviral epidemics have occurred in Mexico and further south in the Americas, local transmission in the United States has been minimal. Here, we study Ae. aegypti and Culex quinquefasciatus host feeding patterns and vertebrate host communities in residential environments of South Texas to identify host-utilization relative to availability. Only 31% of Ae. aegypti blood meals were derived from humans, while 50% were from dogs and 19% from other wild and domestic animals. In Cx. quinquefasciatus , 67% of blood meals were derived from chicken, 22% came from dogs, 9% from various wild avian species, and 2% from other mammals including one human, one cat, and one pig. We developed a model for the reproductive number, R 0 , for Zika virus (ZIKV) in South Texas relative to northern Mexico using human disease data from Tamaulipas, Mexico. We show that ZIKV R 0 in South Texas communities could be greater than one if the risk of human exposure to Ae. aegypti bites in these communities is at least 60% that of Northern Mexico communities. The high utilization of non-human vertebrates and low risk of human exposure in South Texas diminishes the outbreak potential for human-amplified urban arboviruses transmitted by Ae. aegypti .

Venezuelan equine encephalitis (VEE) complex alphaviruses are important re-emerging arboviruses that cause life-threatening disease in equids during epizootics as well as spillover human infections. We conducted a comprehensive analysis of VEE complex alphaviruses by sequencing the genomes of 94 strains and performing phylogenetic analyses of 130 isolates using complete open reading frames for the nonstructural and structural polyproteins. Our analyses confirmed purifying selection as a major mechanism influencing the evolution of these viruses as well as a confounding factor in molecular clock dating of ancestors. Times to most recent common ancestors (tMRCAs) could be robustly estimated only for the more recently diverged subtypes; the tMRCA of the ID/IAB/IC/II and IE clades of VEE virus (VEEV) were estimated at ca. 149-973 years ago. Evolution of the IE subtype has been characterized by a significant evolutionary shift from the rest of the VEEV complex, with an increase in structural protein substitutions that are unique to this group, possibly reflecting adaptation to its unique enzootic mosquito vector Culex (Melanoconion) taeniopus. Our inferred tree topologies suggest that VEEV is maintained primarily in situ, with only occasional spread to neighboring countries, probably reflecting the limited mobility of rodent hosts and mosquito vectors.

Chagas disease, caused by Trypanosoma cruzi, is endemic in southern parts of the American continent. Herein, we have tested the protective efficacy of a DNA-prime/T. rangeli-boost (TcVac4) vaccine in a dog (Canis familiaris) model. Dogs were immunized with two-doses of DNA vaccine (pcDNA3.1 encoding TcG1, TcG2, and TcG4 antigens plus IL-12- and GM-CSF-encoding plasmids) followed by two doses of glutaraldehyde-inactivated T. rangeli epimastigotes (TrIE); and challenged with highly pathogenic T. cruzi (SylvioX10/4) isolate. Dogs given TrIE or empty pcDNA3.1 were used as controls. We monitored post-vaccination and post-challenge infection antibody response by an ELISA, parasitemia by blood analysis and xenodiagnosis, and heart function by electrocardiography. Post-mortem anatomic and pathologic evaluation of the heart was conducted. TcVac4 induced a strong IgG response (IgG2>IgG1) that was significantly expanded post-infection, and moved to a nearly balanced IgG2/IgG1 response in chronic phase. In comparison, dogs given TrIE or empty plasmid DNA only developed high IgG titers with IgG2 predominance in response to T. cruzi infection. Blood parasitemia, tissue parasite foci, parasite transmission to triatomines, electrocardiographic abnormalities were significantly lower in TcVac4-vaccinated dogs than was observed in dogs given TrIE or empty plasmid DNA only. Macroscopic and microscopic alterations, the hallmarks of chronic Chagas disease, were significantly decreased in the myocardium of TcVac4-vaccinated dogs. We conclude that TcVac4 induced immunity was beneficial in providing resistance to T. cruzi infection, evidenced by control of chronic pathology of the heart and preservation of cardiac function in dogs. Additionally, TcVac4 vaccination decreased the transmission of parasites from vaccinated/infected animals to triatomines.