Direct evidence of Rickettsia typhi infection in Rhipicephalus sanguineus ticks and their canine hosts

Murine typhus is a rickettsiosis caused by Rickettsia typhi, whose transmission is carried out by rat fleas in urban settlements as classically known, but it also has been related to cat fleas in a sub-urban alternative cycle that has been suggested by recent reports. These studies remarks that in addition to rats, other animals like cats, opossums and dogs could be implied in the transmission of Rickettsia typhi as infected fleas obtained from serologically positive animals have been detected in samples from endemic areas. In Mexico, the higher number of murine typhus cases have been detected in the Yucatan peninsula, which includes a great southeastern region of Mexico that shows ecologic characteristics similar to the sub-urban alternative cycle recently described in Texas and California at the United States. To find out which are the particular ecologic characteristics of murine typhus transmission in this region, we analyzed blood and Rhipicephalus sanguineus ticks obtained from domestic dogs by molecular approaches, demonstrating that both samples were infected by Rickettsia typhi. Following this, we obtained isolates that were analyzed by genetic sequencing to corroborate this infection in 100% of the analyzed samples. This evidence suggests for the first time that ticks and dogs could be actively participating in the transmission of murine typhus, in a role that requires further studies for its precise description.Keywords: Dogs, Murine typhus, Rhipicephalus sanguineus, Rickettsia typhi, Vecto

Perception of risk among children: Exploring the risk of TB-rickettsial disease based on the children’s drawing pictures in a Mayan community of Yucatan

Background: It is important to work on designs of health promotion strategies that involve educational interventions about the risk factors associated to TB-rickettsiosis (Tick-Borne rickettsiosis). Children’s drawings provide a window into their thoughts and feelings. The aim was to analyze children’s risk perceptions regarding by the presence of ticks in a rural community in southeast Mexico. Methods: The main framework used was a social cognitive perspective under the Health Belief Model. Study was carried out in rural elementary schools and included a drawing contest. A total of 224 children (8-12 years old) participated. Drawings were coded and classified; descriptive trend analysis was performed using counts and percentages. The qualitative data was analyzed by researcher experts in TB- rickettsiosis and using Atlas ti V.8. Results: Results are presented in seven categories that consider environmental elements, actors, and cognitive aspects. The environmental context, 99.1% of the drawings represent sites outside the home (92% include vegetation with the presence of ticks in their immediate external environment). In the actors’ category, 69.6% included people carrying out activities (prevention and risk). As for the cognitive aspects, 70% included domestic pets and 13.4% farmyards animals. Conclusion: The children expressed their ideas about risk factors and preventive measures against TB-rickettsiosis with a self-care approach. They acquired knowledge about preventive strategies and clinical symptoms. It is necessary to evaluate what happens after an intervention and how they implement in their lives what they have learned

Mecanismos de resistencia antifúngica de los azoles en Candida albicans. Una revisión

Candida albicans es una levadura comensal capaz de causar una infección oportunista en hospederos susceptibles denominada candidiasis. El tratamiento para combatir la candidiasis puede ser tópico o sistémico según el tipo de infección, los antifúngicos más utilizados son los derivados imidazólicos (fluconazol, itraconazol, ketoconazol, miconazol etc.), sin embargo en la actualidad se observa una disminución en la efectividad de estos medicamentos, es decir, un fenómeno de resistencia de parte del microorganismo a estos fármacos, esto debido principalmente, al surgimiento de levaduras resistentes, a la aparición de nuevas especies patógenas, a la prescripción irracional de antimicóticos como profilaxis y al aumento de las dosis terapéuticas. Existen dos mecanismos por los que Candida puede adquirir resistencia a un azol. El primero es por mutaciones moleculares de la enzima diana del antifúngico, como la alteración de las enzimas relacionadas en la síntesis del ergosterol y el segundo por la alteración en las bombas de expulsión: ATP-binding cassette (ABC) y facilitadores mayores (MF). En este trabajo se resumen los principales mecanismos de resistencia en Candida y la importancia de hacer pruebas de susceptibilidad con el fin de brindar un tratamiento adecuado para este tipo de infecciones oportunistas

Fatal Human Infection with Rickettsia rickettsii, Yucatán, Mexico

The first fatal Rickettsia rickettsii infection was diagnosed in the southwest of Mexico. The patient had fever, erythematous rash, abdominal pain, and severe central nervous system involvement with convulsive crisis. The diagnosis of R. rickettsii infection was established by immunohistochemistry and specific polymerase chain reaction

Rickettsia typhi en roedores de una comunidad con antecedentes de tifo murino, de Yucatán, México.

Objetivo. Determinar la presencia de Rickettsia typhi en roedores sinantrópicos capturados en la comunidad rural de Bolmay, Yucatán, México, con antecedentes de tifo murino en sus habitantes. Materiales y métodos. Se examinaron 37 roedores: 30 Mus musculus, 6 Rattus rattus y 1 Heteromys gaumeri. Se obtuvo ADN total del bazo de los roedores. La identificación de R. typhi se realizó a través de la amplificación de un fragmento del gen htrA (proteína 17-kDa) por PCR punto final. Los productos positivos fueron purificados y enviados a secuenciación para su análisis de alineamiento con la herramienta BLAST. Resultados. La identificación de ADN rickettsial se logró en un 27% (10/37) de los roedores: siete M. musculus y 3 R. rattus. El análisis de alineamiento obtuvo porcentajes de identidades y coberturas del 97 - 99% para R. typhi, respectivamente. Conclusiones. El presente estudio sugiere la participación de los roedores sinantrópicos en el ciclo de transmisión del tifo murino en la región. Se describe la primera evidencia molecular de R. typhi en M. musculus de Yucatán, México

FRECUENCIA DE LA INFECCIÓN POR VIRUS DE LA HEPATITIS C EN PACIENTES CON CIRROSIS HEPÁTICA EN YUCATÁN.

Introducción. La hepatitis C es causada por el virus de la hepatitis C (VHC), la Organización Mundial de la Salud estima 170 millones de personas se encuentran infectadas por el virus. El 80% de los infectados no elimina el virus de manera natural volviéndose crónico y llevando al desarrollo de cirrosis hepática en el 20% de los casos y carcinoma hepatocelular en el 10%. México se estima una seroprevalencia de 1.5% en la población general, y en Yucatán de 1.6%. En pacientes con cirrosis hepática se estima 32% en el Estado. Objetivo. Detectar la presencia de la infección activa de los VHC en los pacientes con cirrosis hepática que son atendidos en el Hospital General “Dr. Agustín O’Horán” de Mérida Yucatán. Metodología. Se tomaron 62 muestras séricas, se realizó la extracción de ARN total seguido de la síntesis de ADNc, la amplificación de la región 5' no codificante de los VHC con la técnica de reacción en cadena de la polimerasa, obteniendo un amplicon de 144 pares de bases. Resultado y Conclusión. 46.16% de las muestras séricas de los pacientes presentaron genoma viral circulante; hubo un aumento de la cirrosis causada por el VHC en un periodo de 10 años

Rickettsia typhi IN RODENTS AND R. felis IN FLEAS IN YUCATÁN AS A POSSIBLE CAUSAL AGENT OF UNDEFINED FEBRILE CASES

Rickettsia typhi is the causal agent of murine typhus; a worldwide zoonotic and vector-borne infectious disease, commonly associated with the presence of domestic and wild rodents. Human cases of murine typhus in the state of Yucatán are frequent. However, there is no evidence of the presence of Rickettsia typhi in mammals or vectors in Yucatán. The presence of Rickettsia in rodents and their ectoparasites was evaluated in a small municipality of Yucatán using the conventional polymerase chain reaction technique and sequencing. The study only identified the presence of Rickettsia typhi in blood samples obtained from Rattus rattus and it reported, for the first time, the presence of R. felis in the flea Polygenis odiosus collected from Ototylomys phyllotis rodent. Additionally, Rickettsia felis was detected in the ectoparasite Ctenocephalides felis fleas parasitizing the wild rodent Peromyscus yucatanicus. This study’s results contributed to a better knowledge of Rickettsia epidemiology in Yucatán

Design and evaluation of a mobile-based intervention for Maya adults during the COVID-19 pandemic

Introduction: The COVID-19 pandemic has had a direct impact on mental health. International organisations have emphasised the vulnerability of indigenous people. Digital Mental Health approaches deliver online therapy as an evidence-based, effective, and accessible treatment option for common mental health problems. However, the evidence regarding these approaches is limited in indigenous populations. The objective of this study is to describe the design, development, and evaluation of the efficacy of a self-applied online intervention regarding the psychological symptoms of depression, anxiety, and fear of COVID-19 in a sample of the Maya population. Method: A prospective longitudinal quantitative study was designed, where a single group was measured before and after receiving the online intervention. This study took place from April to September 2021 and consisted of six sessions delivered via WhatsApp in Spanish and Mayan. Results: The initial assessment was implemented with 82 participants who were evaluated using the Patient Health Questionnaire, Scale for Generalised Anxiety Disorder and the Fear of COVID-19 Scale; 18 participants remained in the intervention for the post-as-sessment. Statistical differences were observed in PRE and POST measures of depression and anxiety, but not in fear of COVID-19. Conclusions: This study produced positive results for the first online mental health intervention implemented in the Latin American indigenous population. Future studies might consider developing similar interventions for other indigenous communities in Latin America.</p

Rickettsia Vaccine Candidate pVAX1-OmpB24 Stimulates TCD4+INF-&gamma;+ and TCD8+INF-&gamma;+ Lymphocytes in Autologous Co-Culture of Human Cells

Background: In recent years, promising vaccination strategies against rickettsiosis have been described in experimental animal models and human cells. OmpB is considered an immunodominant antigen that is recognized by T and B cells. The aim of this study was to identify TCD4+INF-&gamma;+ and TCD8+INF-&gamma;+ lymphocytes in an autologous system with macrophages transfected with the vaccine candidate pVAX1-OmpB24. Lymphocytes and monocytes from 14 patients with Rickettsia were isolated from whole blood. Monocytes were differentiated into macrophages and transfected with the plasmid pVAX1-OmpB24 pVax1. Isolated lymphocytes were cultured with transfected macrophages. IFN-&gamma;-producing TCD4+ and TCD8+ lymphocyte subpopulations were identified by flow cytometry, as was the percentage of macrophages expressing CD40+, CD80+, HLA-I and HLA-II. Also, we analyzed the exhausted condition of the T lymphocyte subpopulation by PD1 expression. Macrophages transfected with pVAX1-OmpB24 stimulated TCD4+INF-&gamma;+ cells in healthy subjects and patients infected with R. typhi. Macrophages stimulated TCD8+INF-&gamma;+ cells in healthy subjects and patients infected with R. rickettsii and R. felis. Cells from healthy donors stimulated with OmpB-24 showed a higher percentage of TCD4+PD1+. Cells from patients infected with R. rickettsii had a higher percentage of TCD8+PD-1+, and for those infected with R. typhi the larger number of cells corresponded to TCD4+PD1+. Human macrophages transfected with pVAX1-OmpB24 activated TCD4+IFN-&gamma;+ and CD8+IFN-&gamma;+ in patients infected with different Rickettsia species. However, PD1 expression played an important role in the inhibition of T lymphocytes with R. felis

Rickettsia typhi IN RODENTS AND R. felis IN FLEAS IN YUCATÁN AS A POSSIBLE CAUSAL AGENT OF UNDEFINED FEBRILE CASES

Rickettsia typhi es el agente causal del tifo murino; una enfermedad zoonótica transmitida por vector mundialmente distribuida, comúnmente asociada con la presencia de roedores domésticos y silvestres. Los casos humanos de tifo murino en el Estado de Yucatán son frecuentes. Sin embargo, no existe evidencia de la presencia de Rickettsia typhi en mamíferos o vectores en Yucatán. En la búsqueda de vectores y reservorios de Rickettsia typhi, evaluamos la presencia de bacterias del género Rickettsia en roedores y sus ectoparásitos de un pequeño municipio del estado de Yucatán por medio de técnicas de PCR convencional y secuenciación de ADN. Se identificó la presencia de Rickettsia typhi en muestras de sangre obtenidas de Rattus rattus y reportamos por primera vez la presencia de Rickettsia felis en la pulga Polygenis odiosus colectado de Ototylomys phyllotis. Complementariamente, Rickettsia felis fue detectado en la pulga Ctenocephalides felis parasitando al roedor Peromyscus yucatanicus. No se identificó especie de Rickettsia en las muestras de sangre de O. phyllotis y P. yucatanicus analizados. Nuestros resultados contribuyen también en el conocimiento de ciclo de vida biológico del género Rickettsia.Rickettsia typhi is the causal agent of murine typhus; a worldwide zoonotic and vector-borne infectious disease, commonly associated with the presence of domestic and wild rodents. Human cases of murine typhus in the state of Yucatán are frequent. However, there is no evidence of the presence of Rickettsia typhi in mammals or vectors in Yucatán. The presence of Rickettsia in rodents and their ectoparasites was evaluated in a small municipality of Yucatán using the conventional polymerase chain reaction technique and sequencing. The study only identified the presence of Rickettsia typhi in blood samples obtained from Rattus rattus and it reported, for the first time, the presence of R. felis in the flea Polygenis odiosus collected from Ototylomys phyllotis rodent. Additionally, Rickettsia felis was detected in the ectoparasite Ctenocephalides felis fleas parasitizing the wild rodent Peromyscus yucatanicus. This study’s results contributed to a better knowledge of Rickettsia epidemiology in Yucatán