Sokani Sánchez-Montes

First report of “Candidatus Rickettsia amblyommii” in west coast of Mexico

We report the first case of Candidatus Rickettsia amblyommii detected in Amblyomma mixtum ticks on humans on the west coast of Mexico. This is the most western record of Ca. R. amblyommii in the Western Hemisphere, representing the first record for the western coast of the Americas. Even if the record is far from the previously known locations for the species it does not represent a new record regarding temperature, precipitation and topographic parameters. Since Ca. R. amblyommii antibodies have been detected in patients suspected of Rocky Mountain spotted fever, and the tick A. mixtum has been associated with humans, it is important to consider Ca. R. amblyommii as a potential risk for the human population that has not been considered at risk before.

Leptospirosis in Mexico: Epidemiology and Potential Distribution of Human Cases

Background Leptospirosis is widespread in Mexico, yet the potential distribution and risk of the disease remain unknown. Methodology/Principal Findings We analysed morbidity and mortality according to age and gender based on three sources of data reported by the Ministry of Health and the National Institute of Geography and Statics of Mexico, for the decade 2000–2010. A total of 1,547 cases were reported in 27 states, the majority of which were registered during the rainy season, and the most affected age group was 25–44 years old. Although leptospirosis has been reported as an occupational disease of males, analysis of morbidity in Mexico showed no male preference. A total number of 198 deaths were registered in 21 states, mainly in urban settings. Mortality was higher in males (61.1%) as compared to females (38.9%), and the case fatality ratio was also increased in males. The overall case fatality ratio in Mexico was elevated (12.8%), as compared to other countries. We additionally determined the potential disease distribution by examining the spatial epidemiology combined with spatial modeling using ecological niche modeling techniques. We identified regions where leptospirosis could be present and created a potential distribution map using bioclimatic variables derived from temperature and precipitation. Our data show that the distribution of the cases was more related to temperature (75%) than to precipitation variables. Ecological niche modeling showed predictive areas that were widely distributed in central and southern Mexico, excluding areas characterized by extreme climates. Conclusions/Significance In conclusion, an epidemiological surveillance of leptospirosis is recommended in Mexico, since 55.7% of the country has environmental conditions fulfilling the criteria that favor the presence of the disease.

Rickettsia lusitaniae associated with Ornithodoros yumatensis (Acari: Argasidae) from two caves in Yucatan, Mexico

The genus Rickettsia includes obligate intracellular bacteria transmitted by several hematophagous arthropods such as ticks, fleas and sucking lice. In particular hard ticks (Ixodidae) have been cited as the main vectors of pathogenic rickettsiae in Mexico. However, there have been only two records of a single Rickettsia species associated with Mexican soft ticks (Argasidae). In this study, we searched for rickettsial DNA in argasid ticks (13 adults and eight nymphs of Ornithodoros yumatensis) from two bat caves in the state of Yucatan, Mexico. Additionally one larva collected in a cave from Chiapas, Mexico, and associated with Desmodus rotundus was used to corroborate the tick taxonomic determination. Of these, nine ticks (43%) yielded expected PCR products for the rickettsial gltA gene. These PCR-positive ticks were tested with additional PCR protocols targeting the rickettsial genes gltA, ompA and ompB. DNA partial sequences from these genes showed 99-100% identities with Rickettsia lusitaniae, an agent isolated from O. erraticus in Portugal, and closely related to R. felis and R. hoogstraalii. Based on the results from this study, the inventory of rickettsiae distributed in Mexico increases from six to seven species.

Genetic Diversity and Prevalence of Leishmania mexicana in Bichromomyia olmeca olmeca 1 in an Endemic Area of Mexico

Abstract. n Leishmaniases are endemic in southwestern Mexico, and different sand fly species are infected with Leishmania mexicana Biagi. One of the most abundant vectors and dominant species is Bichromomyia olmeca olmeca (Vargas and Díaz-Nájera). We analyzed the genetic variability of Bichromomyia olmeca olmeca and the prevalence of Leishmania mexicana infections with an endemic focus: “the Ejido 20 de Junio” (Mancolona), Campeche, Mexico, where patients with leishmaniases are reported throughout the year. Genetic diversity analysis of 102 sequences of a 270-bp fragment of the 3´ end of mitochondrial cytochrome b (cyt b) gene of Bichromomyia olmeca olmeca revealed 17 haplotypes. The nucleotide diversity and nucleotide polymorphism index were low. The neutrality test and Mismatch test showed population expansion. Prevalence of Leishmania mexicana was 24.5% in 102 females analyzed. This is the first study showing the genetic diversity of Bichromomyia olmeca olmeca sand flies in the Campeche region of Mexico, and also provides novel information on the high infection rate of Bichromomyia olmeca olmeca by Leishmania mexicana. Our finding of high sand fly infection rates during the end of the dry and hot weather of July enriches the literature because high infection rates had been reported only during the rainy season (November) in the region.

Chewing lice (Insecta: Phthiraptera) associated with vertebrates in Mexico

The chewing lice (Insecta: Phthiraptera: Amblycera and Ischnocera) of Mexico have been little studied and many publications include isolated records. This paper summarizes current knowledge of chewing lice recorded from Mexico resulting from an exhaustive search of the literature published from 1866 to 2017. We found 342 louse species associated with 206 bird and 28 mammal species. As a result, we provide a checklist of the chewing lice recorded from Mexico, including a host-parasite list and their geographical distribution within the country.

Detection of pathogenic Leptospira species associated with phyllostomid bats (Mammalia: Chiroptera) from Veracruz, Mexico

The genus Leptospira encompass 22 species of spirochaetes, with ten pathogenic species that have been recorded in more than 160 mammals worldwide. In the last two decades, the numbers of records of these agents associated with bats have increased exponentially, particularly in America. Although order Chiroptera represents the second most diverse order of mammals in Mexico, and leptospirosis represents a human and veterinary problem in the country, few studies have been conducted to identify potential wildlife reservoirs. The aim of this study was to detect the presence and diversity of Leptospira sp. in communities of bats in an endemic state of leptospirosis in Mexico. During January to September 2016, 81 bats of ten species from three localities of Veracruz, Mexico, were collected with mist nets. Kidney samples were obtained from all specimens. For the detection of Leptospira sp., we amplified several genes using specific primers. Amplicons of the expected size were submitted to sequencing, and sequences recovered were compared with those of reference deposited in GenBank using the BLAST tool. To identify their phylogenetic position, we realized a reconstruction using maximum-likelihood (ML) method. Twenty-five samples from three bat species (Artibeus lituratus, Choeroniscus godmani and Desmodus rotundus) showed the presence of Leptospira DNA. Sequences recovered were close to Leptospira noguchii, Leptospira weilii and Leptospira interrogans. Our results include the first record of Leptospira in bats from Mexico and exhibit a high diversity of these pathogens circulating in the state. Due to the finding of a large number of positive wild animals, it is necessary to implement a surveillance system in populations of the positive bats as well as in related species, in order to understand their role as carriers of this bacterial genus.

Redescription of Ornithodoros dyeri (Ixodida: Argasidae) based on morphologic and molecular data

Larvae, nymphs and adults of the cave dwelling tick Ornithodoros dyeri, collected in 3 Mexican states, were studied using morphological and molecular methods. The adults and nymphs were characterized by an elongated body in proportion to the width and a dorsum bounded by two contiguous ridges and one third ridge (inner) that was incomplete on each side. The larvae of this species have 14 pairs of dorsal setae, a venter body with nine pairs of setae plus a posteromedian; a moderately large, dorsal plate and piriform, a hypostome arising from a relatively short, subtriangular median extension of the basis capituli, and a capsule of Halleŕs organ with reticulations. Based on a maximum likelihood analysis of the sequences of a fragment of approximately 414bp of the mitochondrial 16S rRNA gene, we showed that O. dyeri represents an independent lineage within neotropical species of the Argasidae. The bat species Mimon cozumelae and Peropteryx macrotis represents a new host record for this argasid.

Molecular detection of Mycoplasma ovis in an outbreak of hemolytic anemia in sheep from Veracruz, Mexico

Mycoplasma ovis is a small, pleiotropic bacterium, which parasitizes the external surface of erythrocytes of several species of artiodactyl mammals, especially sheep and goats. We here report an outbreak of ovine mycoplasmosis in a sheep flock of a private ranch (Universidad Veracruzana) in Veracruz, Mexico. For the identification of Mycoplasma and other hemoparasitic bacterial agents, we stained blood smears with the DiffQuick® technique and additionally amplified several fragments of 16S rDNA gene. We detected the presence of morulas in erythrocytes from 30 sick female adult sheep, and found Mycoplasma ovis DNA in all of them. Furthermore, three of these animals also tested positive for Anaplasma ovis. Our findings represent the first record of M. ovis and A. ovis in an outbreak of hemolytic anemia in a sheep flock, leading to severe livestock loss in a ranch of Mexico. This study highlights the importance of establishing an active surveillance of both pathogens in the country.

Genetic structure analysis of Amblyomma mixtum populations in Veracruz State, Mexico

Amblyomma mixtum Koch, 1844 parasitizes livestock, humans, and wildlife in Mexico. However, information on population genetics for this tick species in the country is missing. Tick samples were collected from livestock in ten regions across the state of Veracruz (22°28N, 17°09S, 93°36E, 98°39W) to analyze the genetic structure of u2009u2009A. mixtum populations. Ticks were morphologically identified using taxonomic keys. In order to test the intra-specific variability of A. mixtum fragments of the mitochondrial gene 16S-rRNA and cytochrome oxidase subunit 1 (COI) were amplified. Ninety-six sequences were amplified from the 50 specimens analyzed (96% amplification success). Eleven haplotypes were detected in 16S-rRNA gene and 10 more for COI. Neutrality tests showed negative results in most of the locations analyzed, which is indicative of an excess of recently derived haplotypes. However, these results were not statistically significant. Minimal union network analysis revealed that there is no separation of populations by geography, and that there is an overlap of several haplotypes among diverse populations. Significant genetic differentiation was not detected in the A. mixtum populations sampled in the state of Veracruz, Mexico, this may be due to the frequent movement of livestock hosts. This is the first report on the genetic structure of A. mixtum populations in Mexico.

Occurrence of Amblyomma mixtum on the water buffalo (Bubalus bubalis) in Mexico

The water buffalo (Bubalus bubalis) is an Asian species of bovine that was introduced in Mexico in 1992 as an alternative for milk and meat production. To date, no surveys have been conducted to identify ticks acquired by water buffaloes since their arrival in the country. Here we report, for the first time, the presence of Amblyomma mixtum, a neotropical tick in the Amblyomma cajennense complex, found on water buffaloes from Mexico and discuss its possible implications in veterinary public health for the region.