Case Report: Exposure to Relapsing Fever Group Borreliae in Patients with Undifferentiated Febrile Illness in Mexico.

Relapsing fever (RF) borreliosis is a neglected disease in Mexico. A retrospective serological survey using diagnostic antigens GlpQ and BipA from Borrelia turicatae was performed to evaluate human exposure to RF borreliae. Seventy serum samples were used from a cohort of patients with undifferentiated febrile illness in Mexico. Four samples were positive to GlpQ and three to BipA. Results indicate that RF borreliae continue to circulate in regions of Mexico and pose a risk to human health.

Development and validation of a novel detection method for Rickettsia rickettsii using a loop-mediated isothermal amplification assay.

Introduction: Rickettsia rickettsii is an obligate, intracellular pathogen and the causative agent of Rocky Mountain spotted fever (RMSF). RMSF is an important zoonotic disease due to its high fatal outcome in humans. The difficulty of clinical diagnosis due to the low sensitivity and specificity of current diagnostic methods are a principal setback. We reported the development of a new method for the detection of R. rickettsii in human and tick DNA samples using loop-mediated isothermal amplification (LAMP), as well as the validation of the LAMP test for R. rickettsii in field samples of infected ticks and humans, determining the diagnostic sensitivity and specificity, as well as the reproducibility of the test. Methods: This technique uses hydroxy naphthol blue (HNB) as an indicator of the formation of magnesium pyrophosphate, a marker for the presence of DNA. Here, we used a putative R. rickettsii gene as a target for three pairs of primers that specifically amplify R. rickettsii DNA by hairpin-based isothermal amplification technique (LAMP). Results and discussion: The sensitivity of the assay was ~1.6-3 pg, which is 10 times more sensitive than PCR. To determine the diagnostics specificity and sensitivity, 103 human DNA samples and 30 tick DNA samples were evaluated. For the human samples, a sensitivity for HNB of 93%, a specificity of 70% and a k of 0.53 were obtained. For electrophoresis the sensitivity was 97% with a specificity of 58% and a k of 0.42. For tick samples, a sensitivity of 80% was obtained, a specificity of 93% for HNB and for electrophoresis the sensitivity and specificity were 87%. The k for both was 0.73. The degree of concordance between HNB and electrophoresis was 0.82 for humans and for ticks, it was 0.87. The result is obtained in shorter time, compared to a PCR protocol, and is visually interpreted by the color change. Therefore, this method could be a reliable tool for the early diagnosis of rickettsiosis.

Spotted Fever: An Undercover Cause of Hemophagocytic Lymphohistiocytosis in the Immediate Postpartum.

Hemophagocytic lymphohistiocytosis (HLH) is characterized by a dysregulated activation of the immune system that causes fever, cytopenias, organomegalies, and hemophagocytosis. There are infectious, neoplastic, rheumatologic, and miscellaneous causes. Rickettsioses are a neglected cause of HLH. We report a confirmed case of an immunocompetent woman in Mexico with postpartum HLH secondary to spotted fever. We did a review of the literature for search of similar cases. The association between these two diseases was found in postmortem studies, unrelated to postpartum. This diagnosis should be considered in all patients with HLH without an evident cause in areas of epidemiological risk.

Lyme Neuroborreliosis is a Severe and Frequent Neurological Disease in Mexico.

OBJECTIVE: To describe clinical cases with neurological manifestations associated with Borrelia burgdorferi infection in a large cohort of children and adults from Mexico. MATERIAL AND METHODS: Patients with neurological manifestation (cranial neuritis, radiculoneuritis, meningitis and encephalomyelitis) were recruited in one pediatric and two general hospitals, during January 2006-December 2015. Blood and cerebrospinal fluid (CSF) samples were drawn from each patient at inclusion. IgM and IgG antibodies against B. burgdorferi were detected using a commercial ELISA test, and confirmed by Western-Blot test (WB) using three different antigens from Borrelia burgdorferi complex. Following CDC criteria were considered true cases with both positive tests. RESULTS: Of 606 patients recruited, 403 (66.5%) were adults and 203 (33.4%) children, 50.5% were male. B. burgdorferi infection was diagnosed in 168 patients (27.7%), 97 adults, mean age 42 ± 14.7 years and 71 children, mean age 9.6 ± 5 years; early disseminated disease occurred in 130 cases (77.4 %) and chronic stage in 38 (22.6 %). A previous tick bite was reported by 21% cases, and 5% recalled an erythema migrans lesion. Polyradiculoneuropathy and encephalomyelitis were the most common manifestations, whereas 14.8% presented an initial Guillain-Barré Syndrome. B. burgdorferi sensu stricto was identified in 142 (84%) cases, B. garinii in 14 (8%), B. afzelii in three, and nine cases presented coinfection with two species. CONCLUSION: Lyme neuroborreliosis is a frequent condition in patients with neurological diseases in Mexico.

Serological Evidence of Borrelia Burgdorferi Infection in Mexican Patients with Facial Palsy.

BACKGROUND: Facial palsy is the most frequent manifestation of neuroborreliosis in the United States, Europe, and Asia, whereas in Mexico, its frequency is unknown. OBJECTIVE: We aimed to determine the frequency of Borrelia spp. infection in patients with acute facial palsy in Mexico. MATERIALS AND METHODS: In this cross-sectional, referral hospital-based survey, 191 patients with facial palsy were selected and clinical and epidemiologic data recorded. IgM and IgG serum antibodies to Borrelia burgdorferi were tested by enzyme-linked immunosorbent assay (ELISA) and confirmed by Western-Blot (WB). IgM and IgG antibodies against the herpes viruses HSV-1, HSV-2, cytomegalovirus, and Epstein-Barr virus were tested by ELISA. RESULTS: 71 patients (37%) tested positive by ELISA to either Borrelia spp. or the herpes viruses. Of 25 patients (13%) who tested positive for B. burgdorferi by ELISA, 23 (12%) were confirmed by WB; 14 had IgM and 9 had IgG antibodies. Among the 14 IgM-WB positive patients, two cases recognized antigens of B. burgdorferi sensu stricto (s.s.), 10 of Borrelia garinii and 2 of B. afzelii, whereas all 9 IgG-WB positive were reactive against B. burgdorferi s.s. 14 patients had facial palsy in addition to other clinical data compatible with Lyme borreliosis. Patients infected with B. burgdorferi s.s. had a longer recovery time and a significantly higher risk (odds ratio 4.4, 95% confidence interval 1.5-12.9) of recurrent facial palsy than patients infected with other Borrelia genospecies. CONCLUSIONS: Borrelia infection is frequent in facial palsy patients in Mexico, with B. burgdorferi s.s. and B. garinii being the most frequent causative species.

First phylogenetic analysis of Ehrlichia canis in dogs and ticks from Mexico. Preliminary study / Primer análisis filogenético de Ehrlichia canis en perros y garrapatas de México. Estudio preliminar

ABSTRACT Objective. Phylogenetic characterization of Ehrlichia canis in dogs naturally infected and ticks, diagnosed by PCR and sequencing of 16SrRNA gene; compare different isolates found in American countries. Materials and methods. Were collected Blood samples from 139 dogs with suggestive clinical manifestations of this disease and they were infested with ticks; part of 16SrRNA gene was sequenced and aligned, with 17 sequences reported in American countries. Two phylogenetic trees were constructed using the Maximum likelihood method, and Maximum parsimony. Results. They were positive to E. canis 25/139 (18.0%) dogs and 29/139 (20.9%) ticks. The clinical manifestations presented were fever, fatigue, depression and vomiting. Rhipicephalus sanguineus Dermacentor variabilis and Haemaphysalis leporis-palustris ticks were positive for E. canis. Phylogenetic analysis showed that the sequences of dogs and ticks in Mexico form a third group diverging of sequences from South America and USA. Conclusions. This is the first phylogenetic analysis of E. canis in Mexico. There are differences in the sequences of Mexico with those reported in South America and USA. This research lays the foundation for further study of genetic variability.

RESUMEN Objetivos. Caracterizar filogenéticamente Ehrlichia canis a partir de perros naturalmente infectados y sus garrapatas, mediante PCR y secuenciación del gene 16SrRNA para compararlos con diferentes aislados encontrados en el continente Americano. Material y métodos. Se colectaron muestras sanguíneas de 139 perros con manifestaciones clínicas sugestivas a Ehrlichiosis, y que estuvieran infestados con garrapatas; una parte del gene 16SrRNA, fue secuenciada y alineada junto con las 17 secuencias reportadas en los países de América. Se construyeron dos árboles filogenéticos utilizando el método de Máxima verosimilitud compuesta, y Máxima parsimonia. Resultados. Fueron positivos a E. canis 25/139 (18.0%) perros y 29/139 (20.9%) garrapatas colectadas sobre los perros. Las manifestaciones clínicas presentadas fueron fiebre, astenia, depresión y vómito. Las garrapatas Rhipicephalus sanguineus, Dermacentor variabilis y Haemaphysalis leporis-palustris fueron positivas para E. canis. El análisis filogenético mostró que las secuencias 16SrRNA de Ehrlichia canis aisladas de perros y garrapatas en este estudio forman un tercer grupo que diverge de las secuencias de Sudamérica y EUA. Conclusiones. Es el primer análisis filogenético de E. canis en México. Hay diferencias entre las secuencias de este estudio, con las reportadas en otros países de Sudamérica y en EUA. Esta investigación sienta las bases para profundizar en el estudio de la variabilidad genética.

Fatal Monocytic Ehrlichiosis in Woman, Mexico, 2013.

Human monocytic ehrlichiosis is a febrile illness caused by Ehrlichia chaffeensis, an intracellular bacterium transmitted by ticks. In Mexico, a case of E. chaffeensis infection in an immunocompetent 31-year-old woman without recognized tick bite was fatal. This diagnosis should be considered for patients with fever, leukopenia, thrombocytopenia, and elevated liver enzyme levels.

Tick-borne rickettsial pathogens in questing ticks, removed from humans and animals in Mexico.

Tick-borne rickettsial diseases (TBRD) are commonly encountered in medical and veterinary clinical settings. The control of these diseases is difficult, requiring disruption of a complex transmission chain involving a vertebrate host and ticks. The geographical distribution of the diseases is related to distribution of the vector, which is an indicator of risk for the population. A total of 1107 were collected by tick drag from forests, ecotourism parks and hosts at 101 sites in 22 of the 32 states of Mexico. Collected ticks were placed in 1.5 mL cryovials containing 70% ethanol and were identified to species. Ticks were pooled according to location/host of collection, date of collection, sex, and stage of development. A total of 51 ticks were assayed by polymerase chain reaction (PCR) to confirm species identification using morphological methods. A total of 477 pools of ticks were assayed using PCR techniques for selected tick-borne pathogens. Anaplasma phagocytophilum was the most commonly detected pathogen (45 pools), followed by, Ehrlichia (E.) canis (42), Rickettsia (R.) rickettsii (11), E. chaffeensis (8), and R. amblyommii (1). Rhipicephalus sanguineus was the tick most frequently positive for selected pathogens. Overall, our results indicate that potential tick vectors positive for rickettsial pathogens are distributed throughout the area surveyed in Mexico.

Prevalence of Borrelia burgdorferi-infected ticks from wildlife hosts, a response to Norris et al.

In a recent Letter to the Editor, Norris et al. questioned the validity of some of our data reported by Feria-Arroyo et al. The main issue investigated by us was the potential impact of climate change on the probable distribution of the tick vector Ixodes scapularis in the Texas-Mexico transboundary region. As an ancillary issue, an analysis of sequence data for the intergenic spacer of Borrelia burgdorferi was conducted. In the present letter, we provide further evidence supporting our original results, and advocate that extensive study of the population genetics of B. burgdorferi is needed in the Texas-Mexico transboundary region.

Pathogenic Landscape of Transboundary Zoonotic Diseases in the Mexico-US Border Along the Rio Grande.

Transboundary zoonotic diseases, several of which are vector borne, can maintain a dynamic focus and have pathogens circulating in geographic regions encircling multiple geopolitical boundaries. Global change is intensifying transboundary problems, including the spatial variation of the risk and incidence of zoonotic diseases. The complexity of these challenges can be greater in areas where rivers delineate international boundaries and encompass transitions between ecozones. The Rio Grande serves as a natural border between the US State of Texas and the Mexican States of Chihuahua, Coahuila, Nuevo León, and Tamaulipas. Not only do millions of people live in this transboundary region, but also a substantial amount of goods and people pass through it everyday. Moreover, it occurs over a region that functions as a corridor for animal migrations, and thus links the Neotropic and Nearctic biogeographic zones, with the latter being a known foci of zoonotic diseases. However, the pathogenic landscape of important zoonotic diseases in the south Texas-Mexico transboundary region remains to be fully understood. An international perspective on the interplay between disease systems, ecosystem processes, land use, and human behaviors is applied here to analyze landscape and spatial features of Venezuelan equine encephalitis, Hantavirus disease, Lyme Borreliosis, Leptospirosis, Bartonellosis, Chagas disease, human Babesiosis, and Leishmaniasis. Surveillance systems following the One Health approach with a regional perspective will help identifying opportunities to mitigate the health burden of those diseases on human and animal populations. It is proposed that the Mexico-US border along the Rio Grande region be viewed as a continuum landscape where zoonotic pathogens circulate regardless of national borders.

Implications of climate change on the distribution of the tick vector Ixodes scapularis and risk for Lyme disease in the Texas-Mexico transboundary region.

BACKGROUND: Disease risk maps are important tools that help ascertain the likelihood of exposure to specific infectious agents. Understanding how climate change may affect the suitability of habitats for ticks will improve the accuracy of risk maps of tick-borne pathogen transmission in humans and domestic animal populations. Lyme disease (LD) is the most prevalent arthropod borne disease in the US and Europe. The bacterium Borrelia burgdorferi causes LD and it is transmitted to humans and other mammalian hosts through the bite of infected Ixodes ticks. LD risk maps in the transboundary region between the U.S. and Mexico are lacking. Moreover, none of the published studies that evaluated the effect of climate change in the spatial and temporal distribution of I. scapularis have focused on this region. METHODS: The area of study included Texas and a portion of northeast Mexico. This area is referred herein as the Texas-Mexico transboundary region. Tick samples were obtained from various vertebrate hosts in the region under study. Ticks identified as I. scapularis were processed to obtain DNA and to determine if they were infected with B. burgdorferi using PCR. A maximum entropy approach (MAXENT) was used to forecast the present and future (2050) distribution of B. burgdorferi-infected I. scapularis in the Texas-Mexico transboundary region by correlating geographic data with climatic variables. RESULTS: Of the 1235 tick samples collected, 109 were identified as I. scapularis. Infection with B. burgdorferi was detected in 45% of the I. scapularis ticks collected. The model presented here indicates a wide distribution for I. scapularis, with higher probability of occurrence along the Gulf of Mexico coast. Results of the modeling approach applied predict that habitat suitable for the distribution of I. scapularis in the Texas-Mexico transboundary region will remain relatively stable until 2050. CONCLUSIONS: The Texas-Mexico transboundary region appears to be part of a continuum in the pathogenic landscape of LD. Forecasting based on climate trends provides a tool to adapt strategies in the near future to mitigate the impact of LD related to its distribution and risk for transmission to human populations in the Mexico-US transboundary region.

Species distribution models and ecological suitability analysis for potential tick vectors of lyme disease in Mexico.

Species distribution models were constructed for ten Ixodes species and Amblyomma cajennense for a region including Mexico and Texas. The model was based on a maximum entropy algorithm that used environmental layers to predict the relative probability of presence for each taxon. For Mexico, species geographic ranges were predicted by restricting the models to cells which have a higher probability than the lowest probability of the cells in which a presence record was located. There was spatial nonconcordance between the distributions of Amblyomma cajennense and the Ixodes group with the former restricted to lowlands and mainly the eastern coast of Mexico and the latter to montane regions with lower temperature. The risk of Lyme disease is, therefore, mainly present in the highlands where some Ixodes species are known vectors; if Amblyomma cajennense turns out to be a competent vector, the area of risk also extends to the lowlands and the east coast.

Borrelia burgdorferi infection and cutaneous Lyme disease, Mexico.

Four patients who had received tick bites while visiting forests in Mexico had skin lesions that met the case definition of erythema migrans, or borrelial lymphocytoma. Clinical diagnosis was supported with histologic, serologic, and molecular tests. This study suggests the Borrelia burgdorferi infection is in Mexico.

[Seroepidemiologic study of Lyme's borreliosis in Mexico City and the northeast of the Mexican Republic]. / Estudio seroepidemiológico de borreliosis de Lyme en la Ciudad de México y el noreste de la República Mexicana.

OBJECTIVE: To detect serological evidence of B burgdorferi infection in individuals from Mexico City and from the Northeast Region of the country. MATERIAL AND METHODS: A representative sample size of serum from Mexico City and the states of the Northeast of Mexico were taken from serum samples corresponding to the 1987-1988 national survey were obtained from the National Serum Bank. Antibodies against B burgdorferi were detected by ELISA and confirmed with Western blot (WB) assays. Data were analyzed using descriptive statistics. RESULTS: A total of 2,346 serum samples were tested; 297 (12.6%) were positive for ELISA, and 122 of 297 were confirmed by WB. Seroprevalence was 3.43% in Mexico City and 6.2% in the Northeast region of the country. Tamaulipas was the state with the highest seroprevalence. CONCLUSIONS: The prevalence of seropositive cases shows that borrelial infection is present in the northeast of Mexico and Mexico City. Identification of clinical cases and infected tick vectors is necessary to confirm the presence of Lyme disease in Mexico.

Estudio seroepidemiológico de borreliosis de Lyme en la Ciudad de México y el noreste de la República Mexicana / Seroepidemiologic survey of Lyme Borreliosis in Mexico City and the Northeast region of the country

OBJETIVO: Investigar mediante métodos serológicos la infección por B burgdorferi en individuos del Distrito Federal y la zona noreste de México. MATERIAL Y MÉTODOS: Se obtuvo una muestra representativa de sueros del Distrito Federal y la zona noreste de México, obtenidas en la Encuesta Seroepidemiológica Nacional de 1987-1988. Se detectaron anticuerpos IgG vs B burgdorferi por ELISA, confirmados con Western blot. En este trabajo se utilizó estadística descriptiva. RESULTADOS: Fueron estudiados 2 346 sueros; 297 (12.6 por ciento) fueron positivos por inmunoensayo enzimático, y 122/297 fueron confirmados por Western blot. La seroprevalencia fue de 3.43 por ciento en el Distrito Federal y 6.2 por ciento en la zona noreste del país. Tamaulipas fue el estado con la seroprevalencia más alta. CONCLUSIONES: La prevalencia de casos seropositivos sugieren que la infección por B burgdorferi ocurre en el noreste de México y el Distrito Federal. Es necesario identificar casos clínicos y buscar el vector infectado para confirmar la presencia de la enfermedad de Lyme en México