Genetic variation of FTO: rs1421085 T>C, rs8057044 G>A, rs9939609 T>A, and copy number (CNV) in Mexican Mayan school-aged children with obesity/overweight and with normal weight.

OBJECTIVES: Genetic variation of the fat mass and obesity associated gene (FTO) has been identified as a risk factor for obesity and obesity traits. Distribution of FTO single nutleotide polymorphisms (SNPs) rs1421085T>C, rs9939609T>A, rs8057044G>A and copy number variation (CNV) was evaluated in association with childhood obesity or overweight status in children with Mayan ethnicity. METHODS: We included 318 school-aged children with obesity or overweight status (body mass index [BMI]: >85th percentile) and 303 children with normal weight (BMI: 15th-85th percentile). Genotyping was performed using real-time polymerase chain reaction (RT-PCR) with TaqMan probes. The cross-sectional study was carried out using univariate and multivariate logistic regression models adjusted for gender. RESULTS: FTO-SNP rs1421085 showed significant differences between children with obesity and children with normal weight for the heterozygous genotype (P = 0.003) and for allele frequencies (P = 0.023). Adjusting by gender, significant differences were found in frequencies of the hetezygous genotype of SNPs rs9939609 (P = 0.023) and rs1421085 (P = 0.003) as well as in allele frequencies (P = 0.042 and P = 0.013, respectively) between girls with obesity and girls without obesity. In contrast, SNP rs8057044 was significantly different only between heterozygous overweight versus normal weight boys (P = 0.035) and for the allele frequency of rs8057044 (P = 0.021). The mean relative CNV was significantly higher in male overweight children than in boys with normal weight (P = 0.000). CONCLUSIONS: The FTO SNP rs1421085 is a genetic factor associated with obesity in Mayan school-aged children. FTO SNPs rs1421085 and rs9939609 affect genetic susceptibility for obesity only in girls, whereas, SNP rs8057044 and CNV are associated with overweight status only in boys.

Immunogenicity of OmpA and OmpB antigens from Rickettsia rickettsii on mononuclear cells from Rickettsia positive Mexican patients.

Background & objectives: The nature of the rickettsial antigens and the immune response generated by them, have been the subject of exhaustive research so that a suitable vaccine can be developed. Till date evaluations of Rickettsia rickettsii antigens that induce both humoral and cellular responses in animal models have only shown partial protection and short-term immunological memory. This study was aimed to evaluate the immune response induced by DNA plasmids generated from the OmpA and OmpB genes of R. rickettsii in peripheral blood mononuclear cells of rickettsial (sensitized) patients compared to healthy subjects. Methods: Plasmids OmpA-49, OmpB-15 and OmpB-24 were generated in the pVAX vector. Macrophages derived from the THP-1 cell line were transfected in vitro with the plasmids and were co-cultured with T-lymphocytes from sensitized subjects and healthy subjects to evaluate cell proliferation and cytokine production. Results: The OmpB-24 plasmid induced proliferative response in human lymphocytes, with production of IL-2, IFN-γ, IL-12p70, IL-6 and TNF-α, likely due to the presence of conserved epitopes among R. rickettsii, R. typhi and R. felis (differing from 1 to 3 amino acids) during the construction of the plasmids. Interpretation & conclusion: DNA sequences of rickettsial epitopes can be cloned into the pVAX vector. Constructed plasmids can generate a proliferative response and produce cytokines in vitro, in co-culture of transfected macrophages with sensitized human lymphocytes. Plasmid OmpB-24 proved to be the most immunogenic with respect to plasmids OmpA-49 and OmpB-15.

[Knowledge of vector-borne diseases (dengue, rickettsiosis and Chagas disease) in physicians]. / Conocimiento de enfermedades transmitidas por vectores (dengue, rickettsiosis y enfermedad de Chagas) en médicos.

BACKGROUND: The ecological conditions of Yucatan made it a suitable region for the acquisition of vector-borne diseases such as dengue, rickettsiosis, and Chagas disease. As the epidemiological burden of these diseases shows an alarming increase of severe cases, the early establishment of diagnosis and therapeutics by first-contact physicians is a critical step that is not being fulfilled due to several reasons, including poor knowledge. OBJECTIVE: To determine the level of knowledge related to dengue, Chagas disease, and rickettsiosis among rural first-contact physicians of Yucatan. METHODS: A survey was applied to 90 first-contact physicians from rural clinics of Yucatan, which included 32 items related to the diagnosis, treatment, and prevention of dengue, rickettsiosis, and Chagas disease. Answers were analyzed by central tendency statistics. RESULTS: Differences were observed among every category, however; diagnosis and therapeutics showed the lower values. Globally, 62.5% of respondents showed moderate knowledge, 37.5% poor knowledge, and 0% adequate knowledge. DISCUSSION: Results suggest that a strong campaign for a continuous diffusion of knowledge regarding these diseases is needed. In regions with high prevalence of these kinds of diseases, like Yucatan, the impact of these results on the epidemiological burden of these diseases must be evaluated.

ETHNICITY AND INCOME IMPACT ON BMI AND STATURE OF SCHOOL CHILDREN LIVING IN URBAN SOUTHERN MEXICO.

Obesity affects quality of life and increases the risk of morbidity and mortality. Mexico, a middle-income country, has a high prevalence of overweight and obesity among urban children. Merida is the most populated and growing city in southern Mexico with a mixed Mayan and non-Maya population. Local urbanization and access to industrialized foods have impacted the eating habits and physical activity of children, increasing the risk of overweight and obesity. This study aimed to contribute to the existing literature on the global prevalence of overweight and obesity and examined the association of parental income, ethnicity and nutritional status with body mass index (BMI) and height in primary school children in Merida. The heights and weights of 3243 children aged 6-12 from sixteen randomly selected schools in the city were collected between April and December 2012. Multinomial logistic regression models were used to examine differences in the prevalence of BMI and height categories (based on WHO reference values) by ethnicity and income levels. Of the total students, 1648 (50.9%) were overweight or obese. Stunting was found in 227 children (7%), while 755 (23.3%) were defined as having short stature. Combined stunting and overweight/obesity was found in 301 students (9.3%) and twelve (0.4%) were classified as stunted and of low weight. Having two Mayan surnames was inversely associated with having adequate height (OR=0.69, p<0.05) and the presence of two Maya surnames in children increased the odds of short stature and stunting. Children from lower income families had twice the odds of being stunted and obese. Overweight, obesity and short stature were frequent among the studied children. A significant proportion of Meridan children could face an increased risk of developing cardiovascular disease and its associated negative economic and social outcomes unless healthier habits are adopted. Action is needed to reduce the prevalence of obesity among southern Mexican families of all ethnic groups, particularly those of lower income.

[Latinamerican guidelines of RIICER for diagnosis of tick-borne rickettsioses]. / Guías Latinoamericanas de la RIICER para el diagnóstico de las rickettsiosis transmitidas por garrapatas.

Tick-borne rickettsioses are worldwide infectious diseases that are considered emerging and re-emerging. Until recently the only tick-borne rickettsiosis present in Latin America was Rickettsia rickettsii infection, but to date, with the incorporation of new tools as PCR and sequencing and the quick cellular close tube cultures (Shell-vial), new species has been involved as human pathogens. In these guidelines, we offer an update of the microbiological assays for diagnosing rickettsioses. Besides we have included a section in which the most important hard ticks involved in human rickettsioses in Latinoamerica are detailed.

The genus Rickettsia in Mexico: Current knowledge and perspectives.

The genus Rickettsia encompasses 35 valid species of intracellular, coccobacilli bacteria that can infect several eukaryotic taxa, causing multiple emerging and re-emerging diseases worldwide. This work aimed to gather and summarise the current knowledge about the genus Rickettsia in Mexico, updating the taxonomy of the bacteria and their hosts by including all the records available until 2020, to elucidate host-parasite relationships and determine the geographical distribution of each Rickettsia species present in the country. Until now, 14 species of Rickettsia belonging to four groups have been recorded in Mexico. These species have been associated with 26 arthropod species (14 hard ticks, three soft ticks, two sucking lice, and seven fleas) and 17 mammal species distributed over 30 states in Mexico. This work highlights the high biological inventory of rickettsias for Mexico and reinforces the need to approach the study of this group from a One Health perspective.

Murine typhus in child, Yucatan, Mexico.

A case of murine typhus in Yucatan was diagnosed in a child with nonspecific signs and symptoms. The finding of Rickettsia typhi increases the number of Rickettsia species identified in Yucatan and shows that studies are needed to determine the prevalence and incidence of rickettsioses in Mexico.

Human rickettsialpox, southeastern Mexico.

The detection of Rickettsia akari in 2 human patients increased the diversity of rickettsioses affecting the public health in the southeast of Mexico. Rickettsialpox should be considered in the differential diagnosis with other febrile illnesses for the correct diagnosis and accurate treatment of this potential threat to human health.

Severe human infection with Rickettsia felis associated with hepatitis in Yucatan, Mexico.

Rickettsia felis infection usually is a mild-to-moderate illness characterized by general signs and symptoms. Generally, patients do not require hospitalization. However, we detected 2 severe infections with R. felis. Our findings support the importance of R. felis infection as a potentially severe illness in humans.

Rickettsia felis as emergent global threat for humans.

Rickettsia felis is an emergent pathogen belonging to transitional group rickettsiae. First described in 1990, R. felis infections have been reported to occur worldwide in fleas, mammals, and humans. Because clinical signs of the illness are similar to those of murine typhus and other febrile illnesses such as dengue, the infection in humans is likely underestimated. R. felis has been found throughout the world in several types of ectoparasites; cat fleas appear to be the most common vectors. R. felis infection should be considered an emergent threat to human health.

Epidemiologic profile and clinical course of four confirmed rickettsiosis cases in Southern Mexico during 2016.

Domestic animals can carry ticks or fleas, which constitute common vectors of rickettsial infections. The contact with them should be considered as suggestive of rickettsial infections in symptomatic patients. Misdiagnosis might occur in regions where other vector-borne diseases are endemic. Anamnesis is essential for an accurate clinical diagnosis.

Attitudes and Practices from People of a Mayan Community of Mexico, Related to Tick-Borne Diseases: Implications for the Design of Prevention Programs.

BACKGROUND: Tick-borne diseases are caused by several pathogens whose transmission could be associated to the life conditions of communities settled in endemic areas. We aimed to determine the knowledge, attitudes, and practices related to the exposition and prevention of tick-borne diseases among people living in a typical Mayan community of Yucatan, Mexico between Dec 2012 and May 2013. METHODS: A directed survey was applied to 212 (100%) householders (women and men) from Teabo, Yucatan, Mexico. Answers and field notes were recorded and analyzed with central statistics. RESULTS: People have been bitten at least once in the community, but the majority of them consider those bites innocuous. In addition, people do not consider prevention measures, and only a few mentioned the use of some chemicals on their backyards. CONCLUSION: This study found little awareness among the participants regarding the importance and the transmission of these diseases even though they possess a vast knowledge regarding ticks. Therefore, educational strategies and prevention programs that include these habits for its modification are required to minimize the exposition to the vectors.

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.

[Fatal case of rickettsiosis in a toddler from southeastern Mexico]. / Caso fulminante de rickettsiosis (Rickettsia rickettsii) en una lactante del sureste de México.

Rocky Mountain spotted fever is a disease caused by Rickettsia rickettsii, a bacteria transmitted by infected ticks. It is characterized by fever, exanthema, arthralgias and myalgias; but sometimes its clinical presentation is non specific. Due to its similarities with other exanthematic diseases like dengue or chikungunya, Rocky Mountain spotted fever is not a first line diagnosis, even though countries like Mexico show the ecologic and socioeconomic characteristics that favor its transmission, with a 30% mortality rate among pediatric patients. This mortality rate has been associated to a delayed diagnosis and therapy, due to a poor knowledge among physicians regarding this disease; this favors the occurrence of atypical and fulminant cases. The objective of this work is to describe a fulminant case of Rocky Mountain spotted fever, expecting that this disease could be later considered among the differential diagnosis which could directly impact its mortality rate.

La fiebre manchada de las Montañas Rocosas es una enfermedad ocasionada por Rickettsia rickettsii, una bacteria transmitida por garrapatas infectadas, y que se caracteriza por fiebre, exantema, artralgias y mialgias, aunque, ocasionalmente, su presentación es inespecífica. Debido a que su evolución asemeja otras enfermedades exantemáticas, como dengue o chikungunya, su diagnóstico no es de primera intención, a pesar de que países como México tienen las características ecológicas y socioeconómicas propicias para su transmisión, con índices de mortalidad hasta de 30% en pacientes pediátricos. Esta elevada mortalidad se asocia a diagnósticos y terapia retrasados debido al desconocimiento médico acerca de la enfermedad, lo que propicia la aparición de formas atípicas y fulminantes de fiebre manchada de las Montañas Rocosas. El objetivo del presente trabajo es describir un caso clínico fulminante de fiebre manchada de las Montañas Rocosas para que sea considerada en el diagnóstico diferencial, lo cual impactaría directamente en los índices de mortalidad

Rickettsia felis, the agent of an emerging infectious disease: Report of a new case in Mexico.

The fourth case of human infection with Rickettsia felis in Yucatán, Mexico was documented by serologic testing and polymerase chain reaction (PCR). The role of R. felis in human disease has been demonstrated by molecular methods in a few patients from the U.S., Yucatán, Brazil and Germany. Apparently, there is a wide spectrum in the clinical presentation of the worldwide reported cases.

INFECTION BY Rickettsia felis IN OPOSSUMS (Didelphis sp.) FROM YUCATAN, MEXICO.

Rickettsia felis is an emergent pathogen and the causative agent of a typhus-like rickettsiosis in the Americas. Its transmission cycle involves fleas as biological vectors (mainly Ctenocephalides felis) and multiple domestic and synanthropic mammal hosts. Nonetheless, the role of mammals in the cycle of R. felis is not well understood and many efforts are ongoing in different countries of America to clarify it. The present study describes for the first time in Mexico the infection of two species of opossum (Didelphis virginiana and D. marsupialis) by R. felis. A diagnosis was carried out from blood samples by molecular methods through the gltA and 17 kDa genes and sequence determination. Eighty-seven opossum samples were analyzed and 28 were found to be infected (32.1%) from five out of the six studied localities of Yucatan. These findings enable recognition of the potential epidemiological implications for public health of the presence of infected synanthropic Didelphis in households.

[Current review of the epidemiology of leptospirosis]. / Revisión actual de la epidemiología de la leptospirosis.

Spirochete bacteria Leptospira spp. is the causative agent of leptospirosis, antropozoonotic endemic disease in many parts of the world, mainly in underdeveloped countries with high levels of poverty. Its incidence and prevalence rates are higher and important in human populations living in tropical and subtropical climates. Leptospira spp., is capable of infecting more than 160 species of domestic and wild mammals, including human beings, causing various and nonspecific clinical manifestations that make the diagnosis of the disease rarely accurate. In Mexico, the first reports of leptospirosis dating from 1920 and is now considered a matter of public and animal health, mainly for the economic losses it generates. The aim of this paper is to present a review in Spanish, containing the most important aspects in the epidemiology of leptospirosis, to serve as a starting point for students and researchers who are interested about this endemic disease in Mexico.

La bacteria espiroqueta Leptospira spp. es el agente causal de la leptospirosis, enfermedad antropozoonótica endémica en varias regiones del mundo, principalmente en países poco desarrollados y con altos niveles de pobreza. Sus tasas de incidencia y prevalencia son más altas e importantes en poblaciones humanas que habitan en climas tropicales y subtropicales. Leptospira spp., además de afectar al ser humano, es capaz de infectar a más de 160 especies de mamíferos domésticos y silvestres, ocasionando diversas e inespecíficas manifestaciones clínicas que evitan que el diagnóstico de la enfermedad sea certero. En México, los primeros reportes de leptospirosis datan de 1920 y actualmente se le considera un problema de salud pública y pecuaria, principalmente por las pérdidas económicas que genera. El objetivo de este trabajo es presentar una revisión en idioma español, que contenga los aspectos más relevantes en la epidemiología de la leptospirosis, para que sirva de punto de partida a estudiantes e investigadores que tienen interés sobre esta enfermedad endémica en México.

First histopathological study in kidneys of rodents naturally infected with Leptospira pathogenic species from Yucatan, Mexico.

OBJECTIVE: To report the renal histological lesions in synanthropic rodents, Mus musculus and Rattus rattus, naturally infected with Leptospira spp., captured in a rural community in Yucatan, Mexico. METHODS: Kidney samples of synanthropic rodents were collected from a rural community in Yucatan, Mexico. Polymerase chain reaction was used to detect Leptospira spp. infection. Tissue kidney was fixed in 10% buffered formalin, processed according to the usual techniques for paraffin inclusion, cut and stained with hematoxylin and eosin, and examined using a conventional electronic microscope. RESULTS: A total of 187 rodents were captured. Nine individuals (4.8%) were positive for Leptospira spp. in the molecular analysis. All renal lesions observed in the histopathological study had been reported previously for Leptospira spp. infection. CONCLUSIONS: The histopathological lesions are present in the kidneys, plus the results of the polymerase chain reaction confirm that these rodents are true carriers of Leptospira spp.