Since 1996, the incidence of rickettsiosis has been increasing in Yucatán, Mexico, but recent prevalence data are lacking. This study aimed to determine exposure to the Spotted Fever Group (SFG) and Typhus Group (TG) in human serum samples suspected of tick-borne diseases (TBD) between 2015 and 2022. A total of 620 samples were analysed using indirect immunofluorescence assay (IFA) to detect IgG antibodies against SFG (Rickettsia rickettsii) and TG (Rickettsia typhi), considering a titer of ≥64 as positive. Results showed that 103 samples (17%) were positive for R. rickettsii and 145 (24%) for R. typhi, while 256 (41%) and 229 (37%) were negative, respectively. There was a cross-reaction in 244 samples (39%). Individuals with contact with vectors, such as ticks, showed significant exposure to fleas (p = 0.0010). The study suggests a high prevalence of rickettsiosis and recommends prospective studies to assess the disease burden and strengthen surveillance and prevention in Yucatán, considering factors like temperature and ecological changes.

Durante los últimos partidos de la Copa del Mundo FIFA 2022 celebrada en Qatar, Distintos medios informaron que algunos jugadores de la selección francesa presentaron síntomas de una infección viral respiratoria causada por un coronavirus (CoV) conocido desde 2012 con una mortalidad de 30%, el virus, denominado así por ser el agente etiológico del síndrome respiratorio del Oriente Medio (MERS-CoV)

Rickettsia parkeri belongs to the spotted fever group (SFG) of the Rickettsia genus. This bacterium causes mild rickettsiosis in humans and is mainly transmitted by Amblyomma ticks. Its medical importance is emerging in the Americas, including Mexico. Synanthropic rodents and domiciled dogs participate as accidental hosts in epidemiological cycles of Rickettsia of the SFG. The aim is to report the presence of R. parkeri in synanthropic rodents and domiciled dogs from a rural community of Yucatán, Mexico. Rodents were captured, and plasma samples were taken from dogs in 48 households from Ucú, Yucatán, Mexico. A spleen sample (rodents) and plasma (dogs) were used in the propagation of Rickettsia  on Vero cells. These infected cells were used in the extraction of genomic DNA. Rickettsia DNA was identified using a semi-nested PCR (snPCR); some products were sent for sequencing. The recovered sequences were analysed with bioinformatics programs, and a phylogenetic tree was built to determine the Rickettsia species. One hundred animals were sampled: 36 synanthropic rodents and 64 dogs. The snPCR evidenced the presence of Rickettsia DNA in 10 rodents (10/36, 27.8%) and 18 dogs (18/64, 28.1%), which represents a global frequency of 28% (28/100) in this study. The bioinformatics analysis yielded homology to R. parkeri and was demonstrated in the phylogenetic tree. The first evidence of the presence of R. parkeri in synanthropic rodents ( Mus musculus ) from Mexico is presented; likewise, the participation of domestic dogs in the transmission cycle of this bacterium with potential importance in public health is confirmed.

The aim is to describe the Typhus group (TG) Rickettsia infection in dogs and to identify factors associated with this infection. We collected blood samples and gathered exposure and clinical data of 142 dogs from a rural community of Yucatan. The Rickettsia group was determined by semi-nested PCR. Generalized linear models with binomial error distribution were used to model the associated factors from the dog sample for risk ratio (RR) estimation. Thirty-four dogs (23.9%) showed molecular evidence of TG Rickettsia DNA. The multivariate model showed that mixed-breed dogs (RR = 0.06) and dogs that had received antiparasitic treatment (RR = 0.049) had a lower risk of getting infected, taking as reference the purebred group and the non-treated dogs, respectively. Looking at variable interactions, adult dogs without outdoor activities had a lower infection risk than puppies (RR = 0.26). Among dogs with antiparasitic treatment, females had a higher infection risk than male dogs (RR = 26.2). The results showed enzootic TG Rickettsia circulation in dogs of a rural community. The factors outdoor activities, age and previous antiparasitic treatment, as well as the clinical variables signs of hemorrhages and epistaxis, were associated with a less chance of natural infection in the studied dogs. Prevention and control of the enzootic transmission risk of TG Rickettsia should help to reduce the potential zoonotic transmission of this pathogen.

Objetivo. Determinar la circulación del virus del Oeste del Nilo (VON) en caballos del oriente de Yucatán, México. Materiales y métodos. Por conveniencia se estudiaron 184 caballos localizados en 23 unidades de producción de los municipios de Tizimín y Panabá, Yucatán. De cada caballo se obtuvo una muestra de suero sanguíneo, la cual fue evaluada con un ensayo de inmunoabsorción enzimática de captura (MAC-ELISA) para detectar inmunoglobulinas de clase M (IgM) específicas contra VON. Adicionalmente, los sueros seroreactores y los sospechosos fueron analizados con una reacción en cadena de la polimerasa por retrotranscripción (RT-PCR) para detectar ARN viral. Resultados. Ocho caballos estudiados fueron seroreactores en la ELISA-MAC (4.3%, 8/184) y dos fueron sospechosos (1.1%, 2/184). Todos estos sueros fueron negativos a la RT-PCR. Conclusiones. La detección de IgM específicas contra VON en los caballos estudiados, demuestra infecciones recientes e indica la circulación del virus en el oriente de Yucatán.

Infections with viruses of the Flavivirus genus were explored in 22 bats (Artibeus jamaicensis) from Merida, Yucatan, Mexico. The detection of the viral genus was performed by RT-PCR, and infections with dengue (DENV 1-4), West Nile (WNV) and Zika (ZIKV) viruses were subsequently explored. Sequences from positive products were analysed using the BLAST algorithm to determine identity. In 7 (31.8%) and 2 (9.1%) bats, WNV and ZIKV were identified, respectively. The bioinformatic analysis showed 98%-100% coverage and identity for both viruses. Molecular evidence of WNV and ZIKV natural infection in bats from Yucatan, Mexico, is presented.

Objective. To determine the circulation of West Nile virus (WNV) in horses from the eastern Yucatan, Mexico. Materials and Methods. For convenience, 184 horses from 23 production units in the municipalities of Tizimin and Panaba, Yucatan, were studied. A blood serum sample was obtained from each studied horse and evaluated with an immunoglobulin M antibody-capture enzyme-linked immunosorbent assay (MAC-ELISA) to detect immunoglobulin M (IgM) against WNV. Additionally, positive reactor and suspect serum samples were analyzed by reverse transcription polymerase chain reaction (RT-PCR) to detect viral RNA. Results. Eight studied horses were seropositive (4.3%, 8/184) to WNV and two were suspects (1.1%, 2/184). All serum samples were negative by RT-PCR. Conclusions. The detection of IgM specific against WNV in the studied horses shows recent infections with the virus and indicates its circulation in eastern Yucatan, Mexico.

Cases of acute haemorrhagic conjunctivitis (AHC) caused by a coxsackie virus A24 variant (CV-A24v) in Mexico have been reported since 1987; however, no molecular data on the causative strains have been available. Here, we report the identification of the etiological agent responsible for the most recent AHC outbreak in southeastern Mexico (at the end of 2017) as well as the complete genome sequences of seven isolates, using next-generation sequencing (NGS). Phylogenomic analysis of the CV-A24v sequences reported here showed similarity to contemporary strains causing AHC outbreaks in French Guiana and Uganda, forming a novel clade related to genotype IV. Moreover, a specific mutational pattern in the non-structural proteins was identified in the 2017 isolates. This is the first report of genetic characterization of CV-A24v isolates obtained in Mexico.

Toxoplasma gondii is an obligate intracellular protozoan parasite, recognized as the etiologic agent of toxoplasmosis, a zoonotic endemic disease in several countries, including Mexico. In the Yucatan State of Mexico, Toxoplasma infection has a high impact in both human and domestic animal health. Wild animals can also host zoonotic pathogens such as Toxoplasma gondii. The presence of Toxoplasma gondii DNA in roadkill wild animals in Yucatan was detected using a nested Polymerase Chain Reaction. Toxoplasma gondii DNA was identified in several organs retrieved from a Yucatan squirrel (Sciurus yucatanensis), a coatimundi (Nasua narica), and a greater grison (Galictis vittata). The amplified fragments of Toxoplasma gondii DNA were purified, sequenced, and certified by BLAST analysis. Our results confirm that Toxoplasma gondii can infect wild mammals from Yucatan, which could act as intermediate hosts and contribute to the transmission of the disease to humans and domestic animals, as well as other wild animal species. We present the first molecular evidence of Toxoplasma gondii in a squirrel and a coatimundi from Yucatan, and quite possibly in a greater grison at a global level.Figure 1. Agarose gel presenting PCR amplicons (560 bp) positive to Toxoplasma gondii. 1) C+: positive control; A: Yucatan squirrel liver sample; B: great grison femoral muscle sample; C: coatimundi kidney sample; C-: negative control. 2) A: Yucatan squirrel brain sample; B: great grison lung sample; C-: negative control.

Introducción. La leptospirosis es una enfermedad zoonótica endémica en México, ocasionada por la bacteria del género Leptospira, la cual constituye un problema de salud pública y veterinaria. Los roedores son los reservorios más relevantes de Leptospira spp., debido a que la bacteria se establece y se reproduce en su tejido renal y es excretada por la orina.Objetivo. Identificar la presencia de Leptospira spp. en tejido renal de roedores capturados en Yucatán, México.Materiales y métodos. Se capturaron roedores sinantrópicos y silvestres en el municipio rural de Cenotillo, Yucatán, México. Se tomó un riñón de cada roedor y se extrajo el ADN total. La identificación de Leptospira spp. se hizo mediante la detección de dos fragmentos del gen 16S rRNA con una reacción en cadena de la polimerasa (PCR) de punto final. Los productos positivos se secuenciaron y se analizaron con herramientas de alineamiento.Resultados. Se capturaron 92 roedores pertenecientes a siete especies distintas. La PCR arrojó 5,4 % (5/92) de positividad global. El análisis del alineamiento de los aislamientos de los roedores infectados demostró 100 % de cobertura e identidad con la especie Leptospira interrogans. Esta es la primera evidencia molecular de la circulación de Leptospira spp. en Heteromys gaumeri capturados en Yucatán, México.Conclusión. Se evidenció que los roedores de Yucatán, México, son reservorios de Leptospira spp. y participan en el ciclo de infección de la leptospirosis en la región.

Leptospira spp. is a spirochete bacteria, causal agent of leptospirosis, zoonotic disease endemic in Mexico that represents a serious public health and veterinary problem. Rodents are recognised as the most important reservoirs of this bacteria, which is transmitted mainly through direct or indirect contact with the Leptospira spp. excreted in the urine of infected individuals. The aim of this study was to evaluate the circulation of Leptospira spp. in urine samples of wild and synanthropic rodents from Yucatan, Mexico. Eighty-four rodents were captured in the community of Cenotillo, Yucatan. Twenty-six urine samples were collected from the bladder and were used in the total DNA extraction. The identification of Leptospira spp. was intended through the polymerase chain reaction test in its endpoint variant. No evidence of Leptospira spp. was found in the urine samples. It is necessary to use other tissues for the identification of Leptospira spp., before concluding that the rodents used in the present study are not reservoirs of this bacteria.

El objetivo de la presente investigación fue estudiar la presencia de flavivirus en roedores de Yucatán, México, mediante una prueba de Reacción en Cadena de la Polimerasa (PCR), en su variante semi-anidada. Se capturaron 90 roedores (87 Rattus rattus, dos Heteromys gaumeri y un Mus musculus) y se les recolectó una muestra de sangre. Las 90 muestras de suero resultantes fueron agrupadas en 30 triadas (pooles). La PCR semianidada arrojó una frecuencia de positividad del 33.3% (10/30).

The majority of the Yucatan State, Mexico, presents subtropical climate that is suitable for many species of mosquitoes that are known to be vectors of diseases, including those from the genera Aedes and Culex. The objective of this study is to identify the geographic distribution of five species from these two genera and estimate the human population at risk of coming in contact with them. We compiled distributional data for Aedes aegypti (L.), Aedes (Howardina) cozumelensis (Diaz Najera), Culex coronator Dyar and Knab, Culex quinquefasciatus Say, and Culex thriambus Dyar from several entomological studies in Yucatan between March 2010 and September 2014. Based on these data, we constructed ecological niche models to predict the spatial distribution of each species using the MaxEnt algorithm. Our models identified areas with suitable environments for Ae. aegypti in most of Yucatan. A similar percentage of urban (97.1%) and rural (96.5%) populations were contained in areas of highest suitability for Ae. aegypti, and no spatial pattern was found (Moran's I = 0.33, P = 0.38); however, we found an association of abundance of immature forms of this species with annual mean temperature (r = 0.19, P <= 0.001) and annual precipitation (r = 0.21, P <= 0.001). Aedes cozumelensis is also distributed in most areas of the Yucatan State; Cx. quinquefasciatus, Cx. coronator, and Cx. thriambus are restricted to the northwest. The information generated in this study can inform decision-making to address control measures in priority areas with presence of these vectors.

Two ectoparasites, spiny rat mite, Echinolaelaps echidninus (Berlese) (n = 27), and spined rat louse, Polyplax spinulosa (Burmeister) (n = 2), were recorded for the first time in Yucatan State and documented with photographs. The ectoparasites were identified mostly on black rat, Rattus rattus (L.), with serological evidence of flavivirus infection. Adult female E. echidninus was most common and found on black rat with serological evidence of yellow fever, Modoc, and Apoi viruses. We also reported for the first time the cat flea, Ctenocephalides felis (Bouche), on R. rattus. We discussed the potential for the arthropods to bite and transmit pathogens to humans.