Gerardo Álvarez-Hernández

Clinical profile and predictors of fatal Rocky Mountain spotted fever in children from Sonora, Mexico.

Background: Rocky Mountain spotted fever (RMSF) is an increasingly important cause of preventable mortality in children in Sonora, Mexico. Although early treatment with tetracycline has shown to prevent fatal outcome, the disease remains a life-threatening condition, particularly for children. This study describes the clinical factors associated with pediatric mortality due to RMSF in Sonora, in order to guide healthcare practices. Methods: This is a retrospective analysis of 104 children consecutively hospitalized at the major pediatric hospital of Sonora, diagnosed with RMSF between January 2004 and December 2013. Descriptive statistics and multiple logistic regression were used to identify risk factors for fatal outcome. Results: The case fatality ratio in this cohort was 20.2%. Children were hospitalized after a median of 6 days from onset of symptoms including fever (100%), rash involving palms and soles (88.5%) and headache (79.8%); 90.4% of fatal cases had low platelet counts (<50,000/&mgr;L) and 33.3% showed serum creatinine concentrations above the normal value. Acute kidney injury increased mortality, odds ratio (ORadj) = 4.84, 95% confidence interval (CI): 1.2–16.2, as well as delay in treatment (≥ 5th day from onset) with doxycycline, ORadj = 2.62, 95% CI: 1.24–5.52 and hemorrhage, ORadj = 6.11, 95% CI: 1.89–19.69. Conclusions: RMSF is a public health problem in Sonora. Clinically, fatal cases differ from non-fatal cases in renal function and hemorrhagic manifestations, although these findings may occur too late for a timely intervention. First-line providers must be educated to harbor a timely suspicion of RMSF, and should provide empiric treatment with doxycycline when febrile patients first present for care.

Rocky Mountain spotted fever in Mexico: past, present, and future

Rocky Mountain spotted fever, a tick-borne zoonosis caused by Rickettsia rickettsii, is among the most lethal of all infectious diseases in the Americas. In Mexico, the disease was first described during the early 1940s by scientists who carefully documented specific environmental determinants responsible for devastating outbreaks in several communities in the states of Sinaloa, Sonora, Durango, and Coahuila. These investigators also described the pivotal roles of domesticated dogs and Rhipicephalus sanguineus sensu lato (brown dog ticks) as drivers of epidemic levels of Rocky Mountain spotted fever. After several decades of quiescence, the disease re-emerged in Sonora and Baja California during the early 21st century, driven by the same environmental circumstances that perpetuated outbreaks in Mexico during the 1940s. This Review explores the history of Rocky Mountain spotted fever in Mexico, current epidemiology, and the multiple clinical, economic, and social challenges that must be considered in the control and prevention of this life-threatening illness.

Notes from the Field: Community-Based Prevention of Rocky Mountain Spotted Fever — Sonora, Mexico, 2016

Rocky Mountain spotted fever (RMSF), a life-threatening tickborne zoonosis caused by Rickettsia rickettsii, is a reemerging disease in Mexico (1,2). R. rickettsii is an intracellular bacterium that infects vascular endothelium and can cause multisystem organ failure and death in the absence of timely administration of a tetracycline-class antibiotic, typically doxycycline. Epidemic RMSF, as described in parts of Arizona and Mexico, is associated with massive local infestations of the brown dog tick (Rhiphicephalus sanguineus sensu lato) on domestic dogs and in peridomestic settings that result in high rates of human exposure; for example, during 2003-2012, in Arizona the incidence of RMSF in the three most highly affected communities was 150 times the U.S. national average (3,4). In 2015, the Mexico Ministry of Health (MOH) declared an epidemiologic emergency because of high and sustained rates of RMSF in several states in northern Mexico, including the state of Sonora. During 2004-2015, a total of 1,129 cases and 188 RMSF deaths were reported from Sonora (Sonora MOH, unpublished data, 2016). During 2009-2015, one impoverished community (community A) in Sonora reported 56 cases of RMSF involving children and adolescents, with a case-fatality rate of 40% (Sonora MOH, unpublished data, 2016). Poverty and lack of timely access to health services are risk factors for severe RMSF. Children are especially vulnerable to infection, because they might have increased contact with dogs and spend more time playing around spaces where ticks survive (5). In Sonora, case fatality rates for children aged <10 years can be as high as 30%, which is almost four times the aggregate case-fatality rate reported for the general population of the state (8%) (2), and 10-13 times higher than the case-fatality rate described for this age group in the United States (2.4%) (6).

Proposal of a Screening MIRU-VNTR Panel for the Preliminary Genotyping of Mycobacterium bovis in Mexico

Mycobacterium bovis is the major causative agent of bovine tuberculosis, one of the most relevant zoonoses in the world, and affects a wide range of wild and domesticated animals. Development of screening panels in mycobacterial genotyping, according to specific geographical regions, is strongly needed. The aim of this study is to select a panel, constituted by highly polymorphic MIRU-VNTR loci, to discriminate clinical isolates of M. bovis in Mexico. In this study, 65 isolates of M. bovis obtained from clinical bovine samples proceeding from different geographic regions of Mexico were identified by phenotypic and genotypic tests and subsequently genotyped by a 24-locus MIRU-VNTR panel. The most polymorphic loci were selected to build a panel with a high discriminatory power similar to the 24-locus panel results. A panel of seven elements (QUB 11a, MIRU 26, ETR-A, QUB 26, MIRU 16, MIRU 27, and MIRU 39) with the highest allelic diversity showed an appropriate differentiation. The selected MIRU-VNTR elements, according to the regional allelic variability, may be used in the preliminary genotyping of Mycobacterium bovis isolates in Mexico.

Neighborhood socio-environmental vulnerability and infant mortality in Hermosillo, Sonora

OBJECTIVE This paper explores the impact of contextual variables at the neighborhood level on a health marker in the city of Hermosillo, Mexico and discusses the importance of collaboration between planners and health professional to minimize the negative effect of contextual factors on urban health. MATERIALS AND METHODS Few studies in Mexico have assessed health outcomes at the intra-urban scale and their interaction with neighborhood-level contextual variables. Using spatial analysis and geographical information systems, the paper explores the association between infant mortality and an index of socio-environmental vulnerability used to measure urban contextual factors. RESULTS Two high infant mortality clusters were detected within neighborhoods characterized by relatively good environmental conditions and one in a neighborhood with a poor environment. CONCLUSIONS Our results show the clustering of high infant mortality areas and some association with built environment factors in Hermosillo. The results support the need to reconnect public health and urban planning as a way to create healthier environments in Mexican cities.

Effect of the Holiday Season on Weight Gain: A Narrative Review

Several studies suggest that the holiday season, starting from the last week of November to the first or second week of January, could be critical to gaining weight. This study aims to review the literature to determine the effects of the holidays on body weight. In studies of adults, a significant weight gain was consistently observed during this period (0.4 to 0.9 kg, p < 0.05). The only study in college students found an effect on body fat but not on weight (0.1 kg, p = 0.71). The only study found in children did not show an effect on BMI percentile (−0.4%, p > 0.05) during this period. Among individuals with obesity who attempt to lose weight, an increase in weight was observed (0.3 to 0.9 kg, significant in some but not in all studies), as well as increase in weight in motivated self-monitoring people (0.4 to 0.6%, p < 0.001). Programs focused on self-monitoring during the holidays (phone calls and daily mailing) appeared to prevent weight gain, but information is limited. The holiday season seems to increase body weight in adults, even in participants seeking to lose weight and in motivated self-monitoring people, whereas in children, adolescents, and college students, very few studies were found to make accurate conclusions.

Mutaciones asociadas con resistencia a rifampicina o isoniazida en aislamientos clínicos de M. tuberculosis de Sonora, México

OBJETIVO: Realizar el analisis de regiones especificas de genes asociados con resistencia a isoniazida o rifampicina. MATERIAL Y METODOS: Se estudiaron 22 cepas de M. tuberculosis, aisladas en Sonora, Mexico. Se utilizaron iniciadores para regiones especificas de los genes rpoB, katG e inhA y la region ahpC-oxyR. Los productos de PCR se secuenciaron y analizaron. RESULTADOS: Se identificaron mutaciones en la region promotora del gen inhA, region ahpC-oxyR, codon 315 del gen katG y codones 451 o 456 del gen rpoB. CONCLUSIONES: La identificacion de mutaciones no descritas previamente obliga a continuar el analisis genotipico de cepas aisladas en Sonora.

Medical knowledge related to Rocky Mountain spotted fever in Sonora, Mexico

Background Rocky Mountain spotted fever (RMSF) is a tick-borne disease with a high case-fatality rate unless diagnosed promptly and treated timely with doxycycline. Physician knowledge about presentation and treatment can improve outcomes of RMSF in endemic regions, such as Sonora in northern Mexico, where RMSF has caused 1348 non-fatal cases and 247 deaths from 2003 to 2016. Methods A cross-sectional study was conducted with 343 physicians working in medical facilities in Sonora, Mexico. A 25-item questionnaire explored physician knowledge of clinical, epidemiological and preventive aspects of RMSF. Results Only 62% of physicians agreed that doxycycline should be used as the first choice treatment for children under 8 years with suspected RMSF. Additionally, 40% of primary care physicians correctly identified the time to initiate doxycycline, and 32% correctly identified the case-fatality rate of untreated RMSF in all patients. Conclusions Inadequate medical knowledge may adversely affect how patients infected with Rickettsia rickettsii are diagnosed and treated. Educational programs that improve the risk perception and medical knowledge about RMSF should be targeted at physicians most likely to have initial contact with diseased patients.

Una serie de casos fatales de fiebre manchada de las Montañas Rocosas en Sonora, México

INTRODUCTION Rocky Mountain spotted fever is a highly lethal infectious disease, particularly if specific treatment with doxycycline is given belatedly. OBJECTIVE To describe the clinical profile of fatal Rocky Mountain spotted fever cases in hospitalized patients in the state of Sonora, México. MATERIALS AND METHODS We conducted a cross-sectional study on a series of 47 deaths caused by Rickettsia rickettsii from 2013 to 2016. The diagnosis of Rocky Mountain spotted fever was confirmed in a single blood sample by polymerase chain reaction (PCR) or by a four-fold increase in immunoglobulin G measured in paired samples analyzed by indirect immunofluorescence. Clinical and laboratory characteristics were compared stratifying subjects into two groups: pediatric and adult. RESULTS There were no differences in clinical characteristics between groups; petechial rash was the most frequent sign (96%), followed by headache (70%) and myalgia (67%). Although that doxycycline was administered before the fifth day from the onset of symptoms, death occurred in 55% of patients. In clinical laboratory, thrombocytopenia, and biomarkers of liver acute failure and acute kidney failure were the most frequent. CONCLUSION Rocky Mountain spotted fever remains as one of the most lethal infectious diseases, which may be related not only to the lack of diagnostic suspicion and delayed administration of doxycycline, but to genotypic characteristics of Rickettsia rickettsii that may play a role in the variability of the fatality rate that has been reported in other geographical regions where the disease is endemic.

Brote de Chikungunya en el estado de Sonora. El problema de las enfermedades febriles exantemáticas en regiones de clima seco

Sr. editor: La fiebre por Chikungunya (ChikF) es una enfermedad viral transmitida por mosquitos del genero Aedes que permanecio silente hasta el brote en 2005 en las islas del Oceano Indico y que fue reportada en el Continente Americano en 2013, con una rapida diseminacion a lo largo del mismo, incluyendo nuestro pais. Diversos factores se han vinculado con su dispersion; uno de ellos es el cambio climatico que origina la alternancia de lluvias abundantes con epocas de sequia. En ambos extremos, el mosco transmisor ha mostrado capacidad de vivir adecuadamente. Sonora es, en esencia, una region de clima seco y semiseco, a pesar de que 34% de su territorio es de clima muy seco y semicalido…