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This paper aims to describe the natural infection with Dirofilaria immitis in Nasua narica (white-nosed coati) from Yucatán, Mexico. Two carcasses of N. narica were collected on a highway that crosses through a dense forest with patches used for agriculture and livestock activities. We performed necropsies, and two female adult nematode parasites from the heart of one specimen were collected and preserved for their molecular identification using a conventional PCR directed at a fragment of the small subunit (18S) ribosomal RNA (18S-rRNA) gene. Bioinformatic analysis showed a similarity of 99 % with three sequences from D. immitis (two from Japan). Additionally, we performed a phylogenetic tree with the recovered sequence. All these analyses showed that D. immitis is present in N. narica from Mexico. The transmission of D. immitis toward populations of Nasua sp. may be due to indirect and accidental contact with domestic dogs or wild canids that share the same environment. [ABSTRACT FROM AUTHOR]

A geochemical survey of the Las Tres Vírgenes geothermal field (LTVGF), Baja California Sur, Mexico, was carried out to determine the origin and evolution of its fluids, along with the influence of injection of local brines, and inhibitors intended to manage carbonate scaling issues. Major and minor cations, Cl, Br, Sr, O, H, and noble gas (He, Ne, Ar, Kr and Xe) isotopes were measured in fluids collected from four production wells, two injection wells, and one fumarole (El Azufre) in 2016 and 2018. Variations in the stable isotopes of water (δD and δ18O) and halogens (δ37Cl, δ81Br) over the years suggest that local brine reinjection might have started to modify the pristine chemistry of the fluids. However, relevant information on the original geothermal fluids has been preserved. The Na/Br and Cl/Br ratios suggest that LTVGF brines are seawater having leached evaporite deposits (halite). These deposits are absent in the area, but were likely present during the Miocene, prior to the breakup of the Gulf of California, suggesting that the saline fluid end-member at the LTVGF could be several million years old. Measured 3He/4He ratios (R) normalized to the atmospheric ratio Ra (= 1.384 × 10−6) plotted against the 4He/20Ne ratios suggest mixing between a mantle fluid with a R/Ra of 6.19, typical of the sub-continental lithospheric mantle and an atmospheric helium component. The R/Ra versus the 132Xe/36Ar ratio normalized to air suggests mixing between a mantle-rich pre-production fluid and air. The source of air appears to be linked to local gravity-controlled flow reinjection which causes the entrapment of air bubbles, leading to a fluid supersaturated in atmospheric noble gases. This pattern suggests that reinjection fluids are impacting the production area. • Las Tres Vírgenes is the smallest geothermal field in operation in Mexico. • Development is sought but require understanding the present evolution of fluids. • Noble gas isotopic and elemental ratios show air enrichments specific to each well. • These enrichments could indicate that injection is reaching the production zone. [ABSTRACT FROM AUTHOR]

Los Humeros Geothermal Field (LHGF) is one of four geothermal fields currently operating in Mexico, in exploitation since 1990. Located in a caldera complex filled with very low-permeability rhyolitic ignimbrites that are the reservoir cap-rock, recharge of the geothermal field is both limited and localized. Because of this, planning of any future geothermal exploitation must be based on a clear understanding of the fluid circulation. To this end, a first noble gas survey was carried out in which twenty-two production wells were sampled for He, Ne, Ar, Kr, and Xe isotope analysis. Air-corrected 3 He/ 4 He ratios (R c ) measured in the fluid, normalized to the helium atmospheric ratio (R a ; 1.384 × 10 − 6 ), are consistently high across the field, with an average value of 7.03 ± 0.40 R a . This value is close to that of the sub-continental upper mantle, indicating that LHGF mines heat from an active magmatic system. Freshwater recharge does not significantly affect He isotopic ratios, contributing 1–10% of the total fluid amount. The presence of radiogenic 40 Ar* in the fluid suggests a fossil fluid component that might have circulated within the metacarbonate basement with radiogenic argon produced from detrital dispersed illite. Solubility-driven elemental fractionation of Ne/Ar, Kr/Ar, and Xe/Ar confirm extreme boiling in the reservoir. However, a combined analysis of these ratios with 40 Ar/ 36 Ar reveals mixing with an air component, possibly introduced by re-injected geothermal fluids. [ABSTRACT FROM AUTHOR]

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The presence of endocrine disruptors bisphenol-A, bisphenol-A-dimethacrylate, bisphenol-A-diglycidyl-ether, phthalic-acid, dibutyl-phthalate, diethyl-phthalate and dioctyl-phthalate was determined in vegetable cans, baby bottles and microwaveable containers from the Mexican market. Gas-Chromatography-Mass-Spectrometry was used for the identification and High-Performance-Liquid-Chromatography with UV/Visible light and fluorescence detectors was used for the quantification. Endocrine disruptors were found in all samples. PA and DOP were the substances most commonly found, and maximum concentrations were 9.549 and 0.664 μg/kg, respectively from a jalapeno peppers can. Bisphenol A, phthalic-acid, bisphenol-A-dimethacrylate, bisphenol-A-diglycidyl-ether, dioctyl-phtalate and dibutyl-phthalate were found in baby bottles and microwaveable containers. [ABSTRACT FROM AUTHOR]

Concentrations of polychlorinated biphenyls (PCBs) as well as the expression patterns of cytochrome P450 (CYP) enzymes and glutathione- S-transferase (GST) activities were measured in livers of loggerhead ( Caretta caretta), green ( Chelonia mydas), and olive ridley ( Lepidocheyls olivacea) sea turtles from the Baja California peninsula of Mexico. The mean concentrations of total PCBs were 18.1, 10.5, and 15.2 ng/g wet weight (ww) respectively for the three species and PCB 153 was the dominant congener in all samples. Total PCB concentrations were dominated by penta- and hexa-chlorinated biphenyls. The mean estimated TEQs were 42.8, 22.9, and 10.4 pg/g (ww) for loggerhead, green, and olive ridley, respectively, and more than 70% was accounted for by non- ortho PCBs. Western blots revealed the presence of hepatic microsomal proteins that cross-reacted with anti-CYP2K1 and anti-CYP3A27 antibodies but not with anti-CYP1A antibody. There were no significant differences in GST activities between species. Grouping congeners based on structure–activity relationships for CYP isoenzymes suggested limited activity of CYP1A contribution to PCB biotransformation in sea turtles. These results suggest potential accumulation of PCBs that are CYP1A substrates and provide evidence for biotransformation capacity, which differs from known animal models, highlighting the need for further studies in reptiles, particularly those threatened with extinction. [ABSTRACT FROM AUTHOR]

Baja California represents the northernmost reproductive area forLepidochelys olivacea. This region is characterized by its high temperature and low humidity. Thus, nest site selection plays an important role in reproductive success. To evaluate the factors affecting site selection for oviposition Las Barracas Beach, located in the south of the peninsula, was visited, from August to November 2000, in weekly periods. A density of 2.55 nests ha-1 was estimated from a total of 55 nests counted. A hatching success of 73.7% was observed, with 23.7% mortality and 2.5% of eggs without apparent development (eggs counted=4,031). On the day of oviposition, the relative surface humidity (between 0.75% and 1.75%) and temperature (32°C) preferred by the females for nest construction was determined at the nest site, as well as the mean distance between the nests and the high tide line for that day (17.65 m). Hatching success was affected by humidity and distance. In addition, hatching success was higher between 10 and 30 m above the high tide line measured on the day of oviposition (surface humidity ca. 1%). A total of 874 hatchlings were measured, with an average of 42.1 mm straight carapace length. Larger sizes were found in October and smaller ones in November. Generally speaking, the sizes found here were larger than those obtained in other areas. This is probably due to two factors: (1) the nests in Las Barracas were kept in situ, whereas in other areas nests are sometimes incubated artificially and (2) the nesting population of southern Baja California is different from the eastern Pacific population. [ABSTRACT FROM AUTHOR]

• Chlorine and Br isotopic values were determined in geothermal fluids from Mexico. • Relation between δ37Cl, δ81Br and helium isotopic ratio 3He/4He was found. • Relation suggests heavier mantle Cl and Br (+1‰) compared to MORB values. • Heavier δ37Cl, δ81Br might suggest upper mantle chemical heterogeneity. • δ37Cl, δ81Br heavier than chondrites (0‰) might indicate kinetic fractionation during Moon-forming event. Chlorine (Cl) and bromine (Br) are rare elements when considering the whole Earth. However, being highly volatile elements, their delivery and retention processes during planetary accretion and chemical differentiation provide important clues about the formation of the Earth. Variations in Cl and Br isotopic systems (37Cl/35Cl or δ37Cl and 81Br/79Br or δ81Br) among terrestrial reservoirs could trace these processes. While the Br isotopic value of the mantle remains entirely unknown, the measurement of mantle Cl isotopic values is a controversial subject, with measured δ37Cl values ranging from −3 to 0‰ in mid-ocean-ridge basalts (MORBs) and from −2 to +3‰ in oceanic island basalts (OIBs). Here, we report newly-determined δ81Br and δ37Cl values, together with noble gas 3He/4He (R) ratios, measured in geothermal fluids from production wells of three Mexican fields: Cerro Prieto, Las Tres Vírgenes, and Los Azufres. Relationships between 3He/4He ratios and both δ37Cl and δ81Br suggest that geothermal fluid volatiles have three distinct sources: (1) a local crustal source, enriched in radiogenic 4He (R = 1.7–1.9Ra, where Ra is the atmospheric 3He/4He ratio), and halogens from brines with δ37Cl and δ81Br of +0.1 and +0.3‰ respectively; (2) the mantle wedge, with 3He/4He ratios of 6–6.5Ra, typical of arc volcanism, and δ37Cl and δ81Br of −0.4 and −1.0‰ respectively, typical (for Cl) of fluids derived from the dehydration of serpentinite in the subducting slab; and (3) a mantle source, with 3He/4He ratios of 7.7–8.2Ra, typical of MORBs, and δ37Cl and δ81Br of +0.9 and +0.7‰ respectively. These results suggest that the primitive mantle Cl isotopic composition was positive – possibly ≥+3‰, as measured in some OIBs – and inherited during the Moon forming impact. The progressive subduction of isotopically lighter halogens over the last 2–3 Ga could have progressively lowered this initial value to those currently measured in the depleted mantle beneath Mexico. It is speculated that the different isotopic values measured in mantle rocks and fluids could reflect the heterogeneous regassing of subducted halogens and the inefficient homogenization of recycled material in the MORB source, as suggested in other studies by the heterogeneous isotopic compositions of the heavier Ar and Xe of the convective mantle. [ABSTRACT FROM AUTHOR]

The Trans-Mexican Volcanic Belt (TMVB) and the Gulf Extensional Province (Baja California) are the regions in Mexico with the highest heat flow and where the main geothermal energy resources are currently exploited. Here, previously published and newly collected heat and volatile species (He, Ar and CO 2) data from 132 fluid samples of four geothermal areas belonging to TMVB (Los Azufres, Los Humeros, Acoculco and Cerritos Colorados) and two in Baja California (Cerro Prieto and Las Tres Vírgenes) were analyzed. The goal was to identify heat sources, understand how heat is transported into the geothermal reservoirs and how the multiple fluid sources (meteoric, magmatic and crustal) in the reservoir might impact the heat in each field. Distinct R/Ra ratios (where R is the measured 3He/4He ratio and Ra is the atmospheric ratio) are observed in the TMVB and Baja California geothermal fields, with those in the TMVB displaying significantly higher R/Ra values (7.14–7.27) than those in Baja California (1.21–6.62), indicating a higher contribution of mantle helium from possibly younger, active magmatic heat sources. Lower R/Ra values in Baja California might reflect local tectonic features, where reservoirs are primarily affected by crustal contributions from an old, subducted fossil slab related to the Farallon Plate. The analysis of heat to 3He ratios (or Q/3He) together with information provided by 4He/36Ar ratios suggest that heat and volatiles are transferred into the hydrothermal system by advection. The magma bodies beneath the geothermal areas of interest are sufficiently voluminous to provide aqueous fluids by exsolution to sustain this advective flow. The release of He and Ar from magma, during its degassing, appears to be controlled by their diffusivities, fractionating the pristine mantle 4He/36Ar ratio toward higher values, while advection transfers volatiles more rapidly than heat, fractionating the pristine mantle Q/3He ratios toward lower values. The Q/3He vs. 4He/3He relationship shows that boiling and dilution by meteoric water led to further fractionation of heat and volatiles, particularly in Los Azufres and Los Humeros fields, while Cerro Prieto has Q/3He ratios close to those at mid-ocean ridges or fractionated by circulation of low-heat, 4He-rich fossil waters. Distinct sources of heat and volatiles are also reflected in the CO 2 content, the major dry gas component in these geothermal fields. Main sources of CO 2 are mantle carbon (1%-51%) and limestone (34%–100%) from local sources and the subducting slab, although expected fractionation of the C isotopic composition and CO 2 /3He during magma ascent and degassing introduce uncertainties on the precise estimation of each source contributing C to the studied geothermal reservoirs. Yet, contribution of carbon from sediments might be minor (0%–35%), and mainly found in Cerro Prieto and Las Tres Virgenes fields located in Baja California, which are affected by the release of volatiles from the subducted Farallon plate and presence of connate waters in the reservoir of Cerro Prieto. • Heat and helium relationships are investigated in Mexican geothermal fields. • Magma degassing contributes to heat and volatiles in geothermal fluids. • Heat and volatiles are likely transported by advection into the hydrothermal system. • Heat/He ratios well discriminate fluid sources in the geothermal reservoirs. • Previously suggested connate waters in Cerro Prieto field are also evidenced by heat/He ratios. [ABSTRACT FROM AUTHOR]

Major and trace elements, noble gases, and stable (δD, δ 18 O) and cosmogenic ( 3 H, 14 C) isotopes were measured from geothermal fluids in two adjacent geothermal areas in NW-Mexico, Las Tres Vírgenes (LTV) and Cerro Prieto (CP). The goal is to trace the origin of reservoir fluids and to place paleoclimate and structural-volcanic constraints in the region. Measured 3 He/ 4 He (R) ratios normalized to the atmospheric value (R a = 1.386 × 10 −6 ) vary between 2.73 and 4.77 and are compatible with mixing between a mantle component varying between 42 and 77% of mantle helium and a crustal, radiogenic He component with contributions varying between 23% and 58%. Apparent U–Th/ 4 He ages for CP fluids (0.7–7 Ma) suggest the presence of a sustained 4 He flux from a granitic basement or from mixing with connate brines, deposited during the Colorado River delta formation (1.5–3 Ma). Radiogenic in situ 4 He production age modeling at LTV, combined with the presence of radiogenic carbon (1.89 ± 0.11 pmC – 35.61 ± 0.28 pmC) and the absence of tritium strongly suggest the Quaternary infiltration of meteoric water into the LTV geothermal reservoir, ranging between 4 and 31 ka BP. The present geochemical heterogeneity of LTV fluids can be reconstructed by mixing Late Pleistocene – Early Holocene meteoric water (58–75%) with a fossil seawater component (25–42%), as evidenced by Br/Cl and stable isotope trends. CP geothermal water is composed of infiltrated Colorado River water with a minor impact by halite dissolution, whereas a vapor-dominated sample is composed of Colorado River water and vapor from deeper levels. δD values for the LTV meteoric end-member, which are 20‰–44‰ depleted with respect to present-day precipitation, as well as calculated annual paleotemperatures 6.9–13.6 °C lower than present average temperatures in Baja California point to the presence of humid and cooler climatic conditions in the Baja California peninsula during the final stage of the Last Glacial Pluvial period. Quaternary recharge of the LTV geothermal reservoir is related to elevated precipitation rates during cooler-humid climate intervals in the Late Pleistocene and Early Holocene. The probable replacement of connate water or pore fluids by infiltrating surface water might have been triggered by enhanced fracture and fault permeability through contemporaneous tectonic–volcanic activity in the Las Tres Vírgenes region. Fast hydrothermal alteration processes caused a secondary, positive δ 18 O-shift from 4‰ to 6‰ for LTV and from 2‰ to 4‰ for CP geothermal fluids since the Late Glacial infiltration. [ABSTRACT FROM AUTHOR]

The monthly fluctuation of adult Ixodes keiransi in dogs from two cattle farms in southeastern Mexico was determined. In ranch 1 (R1), 6-7 mixed breed dogs from six months to five years of age; while in ranch 2 (R2), 7-8 mixed breed dogs from one to four years of age, were followed. All dogs were monthly inspected for tick infestation through one year. The abundance of dogs infested with ticks was estimated for each month. Tick specimens were taxonomically identified as I. keiransi using morphological features. In R1 the dogs were inspected 60 times and in R2 90 times. The overall proportion of dogs infested by ticks through the year was 75% (60/80) in R1 and 67% (67/90) in R2. The higher abundance of adult I. keiransi parasitizing dogs was from July to December with maximum peaks from September to November. In April, May and June, no ticks were observed on dogs from both ranches. Tick abundance fluctuation showed a concordant pattern with rainfall but with a delay because de maximum peak of I. keiransi abundance was almost two months after the greatest rainfall peak. It is concluded that, in some conditions, the adult I. keiransi in southeastern Mexico presents high-infested rates on dogs and a maximum abundance from September to November. The I. keiransi abundance fluctuation showed a concordant pattern with rainfall., Competing Interests: Declaration of competing interest The authors declare that there is no conflict of interest., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Bats are one of the groups of mammals with the highest number of associated Trypanosoma taxa. There are 50 Trypanosoma species and genotypes infecting more than 75 species of bats across five continents. However, in Mexico, the inventory of species of the genus Trypanosoma associated with bats is limited to only two species (Trypanosoma vespertilionis and Trypanosoma cruzi) even though 140 species of bats inhabit this country. Specifically, 91 bat species have been recorded in the state of Veracruz, but records of trypanosomatids associated with this mammalian group are absent. Due to the complex Trypanosoma-bat relationship, the high diversity of bat species in Veracruz, as well as the lack of records of trypanosomatids associated with bats for this state, the aim of this work was to analyze the diversity of species of the genus Trypanosoma and their presence from a bat community in the central area of the state of Veracruz, Mexico. During the period of January to August 2022 in the Tequecholapa Environmental Management Unit where bats were collected using mist nets and blood samples were obtained from their thumbs. We extracted genetic material and amplified a fragment of 800 bp of the 18S ribosomal gene of the genus Trypanosoma by conventional PCR. The positive amplicons were sequenced, and phylogenetic reconstruction was performed to identify the parasite species. A total of 285 bats (149♀, 136♂) belonging to 13 species from 10 genera and a single family (Phyllostomidae) were collected. Twenty-three specimens from six species tested positive for the presence of Trypanosoma dionisii, Trypanosoma sp. Neobat 4, and a potential novelty species provisionally named as Trypanosoma sp. Neobat 6. The results of the present work increase the number of species of the genus Trypanosoma infecting bats in Mexico and in the Neotropical region., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier B.V.)

This study aims to describe the natural Leptospira occurrence in small mammals from Yucatan, Mexico, and to explore the relation between the characteristics of the capture sites and the Leptospira occurrence. Bats and rodents were captured in five sites of Yucatan state, and from them, a kidney fragment was collected that was used in the genomic DNA extraction. Leptospira DNA was identified by PCR targeting the 16S-rRNA and LipL32 genes. Additionally, a bioinformatic analysis was carried out to know the Leptospira species and was corroborated with a phylogenetic tree. The assemblage of small mammals was compound of 82 (51.2 %) bats and 78 (48.8 %) rodents. A global frequency (bats plus rodents) of Leptospira occurrence of 21.2 % (34/160) was observed; in bats, it was 21.9 % (18/82), and in rodents, 20.5 % (16/78). The phylogenetic trees based on LipL32 gene showed that the recovered sequences most closely resemble the species L. borgpetersenii and L. noguchii. The ordination of the capture sites with tropical deciduous forests as original vegetation is more related to the abundance of Leptospira-infected rodents. The ordination of the capture sites with tropical sub-deciduous forests as original vegetation is more related to the diversity of Leptospira-infected bat species. The canonical ordering of the capture sites is by the original vegetation type and the diversity and abundance of Leptospira-infected bat and rodent species., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

In this survey, we inventoried the helminths of heteromyid and cricetid rodents captured in the Yucatan Peninsula from 2017 to 2019. Helminths were identified using morphological techniques (clearing, staining, and scanning electron microscopy). Also, the 28S rRNA gene of individuals from several helminth taxa was successfully amplified and sequenced. To confirm the identification at the generic level, and in some cases at the specific level, and the genealogical relationships of the parasites, phylogenetic analyses were performed with the new 28S sequences. We identified 22 species of helminths including three trematodes (Brachylaimidae, Dicrocoeliidae, and Microphallidae), five cestodes (Davaineidae, Hymenolepididae, and Taeniidae), and 14 nematodes (Trichuridae, Ancylostomatidae, Ornithostrongylidae, Heligmonellidae, and Oxyuridae) from Heteromys gaumeri (Heteromyidae), Ototylomys phyllotis, Oligoryzomys fulvescens, Peromyscus yucatanicus, Sigmodon toltecus, and Reithrodontomys gracilis (Cricetidae). The overall frequency of infection in small rodents was 84.1% (143/170); all specimens of H. gaumeri, S. toltecus and Ol. fulvescens were infected with helminths. In total, we provided 46 new sequences of the 28S gene from 17 species of helminths. Seven species are likely undescribed species, six are reported for the first time in rodents from Mexico, and 12 are new host records in the Americas. Before this study, 87 taxa of helminths had been reported from 35 cricetid and 12 heteromyid species in 21 Mexican states. Our findings increase to 93 the helminth taxa in these rodents, and to 36 the cricetid species parasitized by helminths. This large scale-survey is the first to use an integrative approach to inventory the helminths of wild small rodents in Mexico.

Trypanosoma cruzi, the causal agent of American trypanosomiasis, and Leishmania spp., the causal agents of Leishmaniasis, are prevalent in more than 20 American countries, including Mexico. Dogs have been reported as incidental hosts for both parasites and may be helpful as transmission sentinels. We surveyed the dog population in a rural locality of the Merida municipality in Yucatan, Mexico, to evaluate the seroreactivity against T. cruzi and Leishmania spp. using two antigens, parasite homogenate (H) and iron superoxide dismutase extract (FeSODe), with two serological techniques (ELISA and Western Blot). Our study found that 3.33% of the tested dogs were seroreactive to T. cruzi using ELISA-H, and 29.5% were seroreactive to FeSODe antigen, with a 94.4% consistency between the two tests. Similarly, for L. mexicana, 1.6% were seroreactive using ELISA-H, and 9.8% were seroreactive using ELISA-FeSODe, with an 83.3% consistency between tests. For L. braziliensis, no dogs were seroreactive using ELISA-H, but 16.4% were seroreactive using ELISA-FeSODe, with a 90% consistency between tests. Finally, for L. infantum, 4.9% were seropositive using ELISA-H, and 6.6% were seropositive using ELISA-FeSODe, with a 75% consistency between tests. These results show noticeable evidence of exposure of dogs to trypanosomatid parasites and highlight the potential disease risk for the people and their companion animals in the region., Competing Interests: Declaration of Competing Interest None., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Helminth species of Neotropical bats are poorly known. In Mexico, few studies have been conducted on helminths of bats, especially in regions such as the Yucatan Peninsula where Chiroptera is the mammalian order with the greatest number of species. In this study, we characterized morphologically and molecularly the helminth species of bats and explored their infection levels and parasite–host interactions in the Yucatan Peninsula, Mexico. One hundred and sixty-three bats (representing 21 species) were captured between 2017 and 2022 in 15 sites throughout the Yucatan Peninsula. Conventional morphological techniques and molecular tools were used with the 28S gene to identify the collected helminths. Host–parasite network analyses were carried out to explore interactions by focusing on the level of host species. Helminths were found in 44 (26.9%) bats of 12 species. Twenty helminth taxa were recorded (7 trematodes, 3 cestodes and 10 nematodes), including 4 new host records for the Americas. Prevalence and mean intensity of infection values ranged from 7.1 to 100% and from 1 to 56, respectively. Molecular analyses confirmed the identity of some helminths at species and genus levels; however, some sequences did not correspond to any of the species available on GenBank. The parasite–host network suggests that most of the helminths recorded in bats were host-specific. The highest helminth richness was found in insectivorous bats. This study increases our knowledge of helminths parasitizing Neotropical bats, adding new records and nucleotide sequences.

This review compiles the studies (2007-2021) regarding the occurrence of emerging organic contaminants (EOCs) and endocrine disruptors (EDs) in wastewater, surface water and groundwater in Mexico. A total of 174 compounds were detected, including pharmaceuticals, hormones, plasticizers, personal care products, sweeteners, drugs, and pesticides considered as EDs. The levels of EOCs and EDs varied from ng/L to 140 mg/L, depending on the compound, location, and compartment. Raw wastewater was the most studied matrix, showing a greater abundance and number of detected compounds. Nevertheless, surface waters showed high concentrations of bisphenol-A, butylbenzil-phthalate, triclosan, pentachlorophenol, and the hormones estrone, 17 α-ethinylestradiol, and 17 β-estradiol, which exceeded the thresholds set by international guidelines. Concentrations of 17 α-ethinylestradiol and triclosan exceeding the above-mentioned limits were reported in groundwater. Cropland irrigation with raw wastewater was the principal activity introducing EOCs and EDs into groundwater. The groundwater abundance of EOCs was considerably lesser than that of wastewater, highlighting the attenuation capacity of soils/aquifers during wastewater infiltration. However, carbamazepine and N,N-diethyl-meta-toluamide showed higher concentrations in groundwater than those in wastewater, suggesting their accumulation/concentration in soils/pore-waters. Although the contamination of water resources represents one of the most environmental concerns in Mexico, this review brings to light the lack of studies on the occurrence of EOCs in Mexican waters, which is important for public health policies and for developing legislations that incorporates EOCs as priority contaminants in national water quality guidelines. Consequently, the development of legislations will support regulatory compliance for wastewater and drinking water, reducing the human exposure., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Diabetic kidney disease (DKD) is one of the more limiting complications to the quality of life of diabetes mellitus patients. Studies including cultured cells, animal models, and case-control studies highlight the role of human β-defensin-1 (hBD-1) in diabetes.This study assessed the association of hBD-1 gene ( DEFB1 ) functional variations -52 G/A (rs1799946), -44 C/G (rs1800972) and -20 G/A (rs11362) with type 2 diabetes mellitus (T2DM) in order to investigate its effects on genetic susceptibility and progression to DKD in a Mexican population. A total of 214 T2DM patients with and without DKD (n = 102 and n = 112, respectively) and 117 healthy subjects participated in this case-control study. Genotyping was made by PCR-RFLPs. Clinical and biochemical parameters of all patients were measured. There was no statistically significant difference in genotype or allele frequencies between patients and healthy individuals. Nevertheless, compared with patients without DKD, DKD patients have a reduced prevalence of AA genotype of -52 G/A (OR = 0.307, 95% CI = 0.104-0.905, p = .026), as well as a higher frequency of GA genotype of -20 G/A variant (OR = 1.875, 95%CI = 1.031-3.409, p =  .038). Our results suggest that rs1799946 and rs11362 could be useful variants to stratify T2DM Mexican patients in order to prescribe closer follow-up to prevent or retard DKD. Further tests in different ethnic groups are encouraged.

Human tick-borne rickettsioses are caused by Rickettsia africae, Rickettsia massiliae, Rickettsia parkeri, Rickettsia philipi and Rickettsia rickettsii in the American continent. Rickettsia parkeri represents the second most important agent of eschar-associated spotted fever throughout the American continent. In Mexico, the presence of three strains of this bacterium (Black Gap, Maculatum and Atlantic Rainforest) has recently been reported in four species of ticks from five states (Baja California, Campeche, Sonora, Tabasco and Veracruz) and rickettsaemia was demonstrated in a dog from the state of Yucatán. We report two human cases of R. parkeri-rickettsiosis from Yucatan, Mexico. These findings have increased the interest in R. parkeri surveillance in the human population, due to the fluctuating regional Spotted Fever morbidity and mortality in the country., (© 2022 Wiley-VCH GmbH.)

Infections with viruses of the Flavivirus genus were explored in 22 bats (Artibeus jamaicensis) from Merida, Yucatan, Mexico. The detection of the viral genus was performed by RT-PCR, and infections with dengue (DENV 1-4), West Nile (WNV) and Zika (ZIKV) viruses were subsequently explored. Sequences from positive products were analysed using the BLAST algorithm to determine identity. In 7 (31.8%) and 2 (9.1%) bats, WNV and ZIKV were identified, respectively. The bioinformatic analysis showed 98%-100% coverage and identity for both viruses. Molecular evidence of WNV and ZIKV natural infection in bats from Yucatan, Mexico, is presented., (© 2021 Wiley-VCH GmbH.)

Introduction: Bats have been reported as hosts of the Trypanosoma cruzi protozoan, the etiologic agent of American trypanosomiasis, an endemic zoonotic disease in México., Objective: To describe T. cruzi infection in bats from the states of Campeche and Yucatán, México., Materials and Methods: Captures were made from March to November, 2017, at three sites in Yucatán and one in Campeche. Up to four mist nets on two consecutive nights were used for the capture. The bats' species were identified and euthanasia was performed to collect kidney and heart samples for total DNA extraction. Trypanosoma cruzi infection was detected by conventional PCR with the amplification of a fragment belonging to the T. cruzi DNA nuclear., Results: Eighty-six bats belonging to five families (Vespertilionidae, Noctilionidae, Mormoopidae, Phyllostomidae, and Molossidae) and 13 species (Rhogeessa aeneus, Noctilio leporinus, Pteronotus davyi, P. parnellii, Artibeus jamaicensis, A. lituratus, A. phaeotis, Glossophaga soricina, Carollia sowelli, Chiroderma villosum, Uroderma bilobatum, Sturnira parvidens, and Molossus rufus) were captured. Infection frequency by PCR was 30,2% (26/86) detected only in the renal tissue. The infected species were P. parnellii, G. soricina, A. lituratus, A. jamaicensis, S. parvidens, C. villosum, and R. aeneus., Conclusions: Our results confirmed the participation of several bat species as hosts in the T. cruzi transmission cycle in the region. Further studies are necessary to establish the importance of these animals in the zoonotic transmission of T. cruzi.

Introduction: The vector-borne diseases program in México has an established network of ovitraps for entomological surveillance of Aedes spp. In response to reports of Aedes albopictus in the periphery of Mérida, the state capital of Yucatán, the Ministry of Health increased the specificity of this surveillance. Objective: To describe the presence and distribution of Ae. albopictus in Mérida and its relative abundance compared to Aedes aegypti in ovitraps of the vector control program. Materials and methods: During October, 2019, 91 ovitraps were randomly selected from 31 neighborhoods of Mérida. Mosquitoes were reared at the insectary of the Collaborative Unit for Entomological Bioassays of the Autonomous University of Yucatán from eggs collected in the field. Relative abundance was determined for adult individuals of each identified species and neighborhood. Results: 32 % of the neighborhoods were positive for Ae. albopictus and 100 % for Ae. aegypti. A total of 28 adults of Ae. albopictus (10 females and 18 males) were obtained from ovitraps. No correlation was observed between the abundance of Ae. aegypti and Ae. albopictus for both adults and females (p>0.05) at the neighborhood level. Conclusions: The results confirm that Ae. albopictus coexisted with Ae. aegypti in Mérida at the time of the study. The low relative abundance suggests that Ae. albopictus was in the initial phase of invasion.

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., (Copyright © 2020 Elsevier GmbH. All rights reserved.)

Since the emergence of the COVID-19 pandemic, the most affected population group has been that of older people living in long-term care facilities (LTCFs), which has accumulated between 30 and 60 % of total number of deaths in the world. In Mexico, outbreaks have been reported in LTCFs of at least eight states. Various factors make this population group and LTCFs susceptible to COVID-1 outbreaks, mainly due to coexistence in common spaces, shared bedrooms and permanent physical contact with the personnel who work there, coupled with a lack of protocols and standards of care of mandatory observance, as well as personnel training limitations. There is evidence of the need to formally develop a National Care System that provides support to those in need of care and their families, and that includes LTCFs. In view of the challenges due to the lack of information and competencies in infection prevention and control at LTCFs, a group of experts, in collaboration with different public institutions, joined efforts with the purpose to update the guidelines in order to allow LTCFs face the pandemic and to contribute to the generation of said National Care System., (Copyright: © 2020 Permanyer.)

The aim of the study was to describe the epidemiological factors associated with the risks of recent Rickettsia exposure in inhabitants of a rural population from Yucatán, Mexico. The study included 130 inhabitants from Maxcanú, Yucatán. Blood samples were collected to detect IgM and IgG antibodies against Rickettsia typhi and Rickettsia rickettsii by an indirect immunofluorescence antibody test. Additionally, nested polymerase chain reaction was performed to amplify fragments of the 17kDa and sca5 genes. Previously, an epidemiological questionnaire was applied focused on collecting information on personal and housing exposure variables related to the recent infection with Rickettsia to determine epidemiological associations. Results that exhibited a p-value < .25 were included in a generalized multinomial logistic linear model to determine the variables involved with the risk of contact or Rickettsia infection. In all, 76% (99/130) of the participants presented with immunoglobulin titres against the Rickettsia species evaluated, while rickettsial DNA was detected in 35.4% (46/130) of the participants. The association analysis with the personal exposure variables showed that the productive age group (OR = 0.32; 95% CI = 0.10-1.03) and the elders group (OR = 0.12; 95% CI = 0.01-0.83) were protective factors for recent infection with R. typhi, taking as reference the school group. The presence of a family orchard in the home (OR = 7.56; 95% CI = 1.62-35.29) was a risk factor for recent infection with R. rickettsii. Presumably, the presence of ectoparasites (OR = 2.71; 95% CI = 0.90-8.09) at home was a risk factor for recent infection with both Rickettsia species. Recent infection was demonstrated in inhabitants from Maxcanú, Yucatán. A high seropositive frequency was obtained. The results highlight the importance of the family garden and the presence of ectoparasites in the home as risk factors associated with recent infection with Rickettsia in inhabitants from Maxcanú., (© 2020 Blackwell Verlag GmbH.)

Introduction: Trypanosoma cruzi is the causal agent of the American trypanosomiasis, an endemic disease in México. The commensal rodents Mus musculus and Rattus rattus are reservoirs of this parasite, which invades cardiac fibers and develops parasite nests causing various lesions. Histopathological studies in naturally infected rodents are scarce. Objective: To describe the types and frequencies of microscopic lesions in cardiac tissue of M. musculus and R. rattus infected with T. cruzi captured in Mérida, México. Materials and methods: The rodents were captured in suburban environments of Mérida. Cardiac tissue was extracted and processed by the paraffin inclusion technique and hematoxylin and eosin stained. The observation was made with a conventional microscope and all the lesions, as well as their degree, were identified. Results: Eight tissue samples of M. musculus and seven of R. rattus were studied. Parasite nests were found in 7/15, specifically 3/8 in M. musculus and 4/7 in R. rattus. The inflammatory infiltrate was the most frequent lesion. Other lesions were: Degeneration of cardiac fibers (8/15), congestion of blood vessels (6/15), and necrosis (5/15). Discussion: The lesions we observed have been described in experimental animal models and in humans with American trypanosomiasis. The inflammatory infiltrate has been identified as the most significant lesion in humans and reservoirs in the chronic stage of the disease. Conclusion: The lesions we described are associated with T. cruzi infection, which confirms that the rodents studied are reservoirs of this parasite.

Acanthamoeba keratitis (AK) is a sight-threatening corneal infection. The early symptoms include redness, pain, photophobia and intense tearing. Chronic infection usually progresses to stromal inflammation, ring ulcers, corneal opacification and hypopyon. Here we document an AK case in a high myopic 38-year-old woman from Mexico City, with a history of wearing contact lenses while swimming. Corneal scrapes cultures were positive only for amoebae, consequently a treatment including netilmicin 0.3% and oral itraconazole 100 mg/12 h was prescribed. The infection was resolved after 8 months, leaving a slight leucoma outside the visual axis, with a visual acuity of 20/150. In the laboratory, the amoebic isolate was axenized in PYG medium, with an optimal growth at 30 °C, and was identified morphologically as Acanthamoeba polyphaga according to the taxonomic criteria of Page (1988) and placed in the T4 group by genotyping. The virulence of this strain (40%) was determined by intranasal inoculation of 1 × 10 6 /20 μl trophozoites in BALB/c mice recovering from brain, proving their invasion ability and by the interaction with monolayers of epithelial cells of the established MDCK line of canine kidney origin (1:2 ratio of interaction), at 1, 3, 6, 8 and 24 h; trophozoites migrated to cell junctions inducing few lytic zones. In addition to the biological characterization, in vitro drug sensitivity tests were performed using chlorhexidine, itraconazole, netilmicin and voriconazole. Results revealed that voriconazole was the most effective compound. A. polyphaga remains as one of the most frequently isolated species producing AK. The treatment of AK case using netilmicin and oral itraconazole solved the disease, but the healing process was wide-ranging (8 months). The use of voriconazole and chlorhexidine may be an alternative treatment of future AK cases in Mexico., (Copyright © 2018. Published by Elsevier Inc.)

Introduction: Leptospirosis is a zoonotic disease caused by bacteria of the genus Leptospira, which is endemic in México and considered a public and veterinary health problem. Rodents are the most relevant reservoirs of Leptospira spp. because the bacteria establish and reproduce in its renal tissue and are excreted through the urine. Objective: To identify the presence of Leptospira spp. in renal tissue from rodents captured in Yucatán, México. Materials and methods: Synanthropic and wild rodents were captured in the rural municipality of Cenotillo, Yucatán, México. We collected one kidney from each rodent and extracted the total DNA. The identification of Leptospira spp. was done by detecting two fragments of the 16S rRNA gene using end-point polymerase chain reaction (PCR). We sequenced and analyzed positive products using alignment tools. Results: A total of 92 rodents belonging to seven different species were captured. The PCR yielded a global positivity of 5.4% (5/92). The alignment analysis of the sequenced products demonstrated a 100% of coverage and identity with Leptospira interrogans. This is the first molecular evidence of Leptospira spp. circulation in Heteromys gaumeri captured in Yucatán, México. Conclusion: Our results evidenced that rodents of Yucatán are reservoirs of Leptospira spp. and participate in the infection cycle of leptospirosis in the region.

The house mouse (Mus musculus) and the black rat (Rattus rattus) are reservoir hosts for zoonotic pathogens, several of which cause neglected tropical diseases (NTDs). Studies of the prevalence of these NTD-causing zoonotic pathogens, in house mice and black rats from tropical residential areas are scarce. Three hundred and two house mice and 161 black rats were trapped in 2013 from two urban neighbourhoods and a rural village in Yucatan, Mexico, and subsequently tested for Trypanosoma cruzi, Hymenolepis diminuta and Leptospira interrogans. Using the polymerase chain reaction we detected T. cruzi DNA in the hearts of 4·9% (8/165) and 6·2% (7/113) of house mice and black rats, respectively. We applied the sedimentation technique to detect eggs of H. diminuta in 0·5% (1/182) and 14·2% (15/106) of house mice and black rats, respectively. Through the immunofluorescent imprint method, L. interrogans was identified in 0·9% (1/106) of rat kidney impressions. Our results suggest that the black rat could be an important reservoir for T. cruzi and H. diminuta in the studied sites. Further studies examining seasonal and geographical patterns could increase our knowledge on the epidemiology of these pathogens in Mexico and the risk to public health posed by rodents.

Background: Previous healthy lifestyle interventions based on the Salud para Su Corazón curriculum for Latinos in the United States, and a pilot study in Guatemala, demonstrated improvements in patient knowledge, behavior, and clinical outcomes for adults with hypertension. This article describes the implementation of a healthy lifestyle group education intervention at the primary care health center level in the capital cities of Costa Rica and Chiapas, Mexico for patients with hypertension and/or type 2 diabetes and presents impact evaluation results., Methods: Six group education sessions were offered to participants at intervention health centers from November 2011 to December 2012 and participants were followed up for 8 months. The study used a prospective, longitudinal, nonequivalent pretest-posttest comparison group design, and was conducted in parallel in the two countries. Cognitive and behavioral outcome measures were knowledge, self-efficacy, stage-of-change, dietary behavior and physical activity. Clinical outcomes were: body mass index, systolic and diastolic blood pressure, and fasting blood glucose. Group by time differences were assessed using generalized estimating equation models, and a dose-response analysis was conducted for the intervention group., Results: The average number of group education sessions attended in Chiapas was 4 (SD: 2.2) and in Costa Rica, 1.8 (SD: 2.0). In both settings, participation in the study declined by 8-month follow-up. In Costa Rica, intervention group participants showed significant improvements in systolic and diastolic blood pressure and borderline significant improvement for fasting glucose, and significant improvement in the stages-of-change measure vs. the comparison group. In Chiapas, the intervention group showed significant improvement in the stages-of-change measure in relation to the comparison group. Significant improvements were not observed for knowledge, self-efficacy, dietary behavior or physical activity. In Chiapas only, a significant dose-response relationship was observed for systolic and diastolic blood pressure., Conclusion: Group education interventions at health centers have the potential to improve stage-of-change activation, and may also improve clinical outcomes. In the future, it will be essential to dedicate resources to understand ways to reach a representative group of the patient population, tailor the intervention so that patients are engaged to participate, and consider the broader family and community context that influences patients' capacity to manage their condition.

Background: Chagas disease is a parasitic disease caused by the protozoan parasite Trypanosoma cruzi. In Mexico, the burden of the disease is difficult to estimate and improving surveillance for Chagas disease is an important priority. We aimed here at determining the seroprevalence of T. cruzi infection in humans in a rural community in Veracruz., Methods: Serum samples (196) were analyzed for T. cruzi infection using five enzyme-linked immunosorbent assay (ELISA) tests: two in-house tests based on crude parasite extract and three commercial ELISA kits. Because of highly discordant results, we further explored the importance of parasite antigens and strains by western-blot analysis., Results: A total of 74 samples (37.7 %) were reactive with at least one ELISA, but discordance among tests was very high. The best agreement was between Chagatest recombinant and Chagatek ELISA (Kappa index = 0.798). The agreement between other combinations of tests ranged from 0.038 to 0.518. Discordant samples were confirmed by western-blot analysis using up to nine parasite strains, giving a seroprevalence of 33.7 %., Conclusions: Commercial tests had a very limited ability to detect T. cruzi infection in the study population. In-house tests based on crude parasite antigens showed a greater sensitivity but were still unable to detect all cases of T. cruzi infection, even when based on a local parasite strain. The high seroprevalence confirmed the hyper-endemicity of T. cruzi infection in the region. Reliable epidemiological surveillance of Chagas disease will require the development of improved diagnostic tests.

Chagas disease, or American trypanosomiasis, which is caused by the protozoan parasite Trypanosoma cruzi, is primarily a vector disease endemic in 21 Latin American countries, including Mexico. Although many vector control programs have been implemented, T. cruzi has not been eradicated. The development of an anti-T. cruzi vaccine for prophylactic and therapeutic purposes may significantly contribute to the transmission control of Chagas disease. Immune protection against experimental infection with T. cruzi has been studied since the second decade of the last century, and many types of immunogens have been used subsequently, such as killed or attenuated parasites and new DNA vaccines. This primary prevention strategy appears feasible, effective, safe, and inexpensive, although problems remain. The objective of this review is to summarize the research efforts about the development of vaccines against Chagas disease worldwide. A thorough literature review was conducted by searching PubMed with the terms "Chagas disease" and "American trypanosomiasis" together with "vaccines" or "immunization". In addition, reports and journals not cited in PubMed were identified. Publications in English, Spanish, and Portuguese were reviewed.

Objective: Galicia is the Spanish region in which most bovine spongiform encephalopathy cases have been registered. Meixoeiro Hospital is included in the Galician Health Service (SERGAS). The aim of the study was to analyze the clinical and epidemiological characteristics of Creutzfeldt-Jakob disease (CJD) in the health area of Meixoeiro Hospital and to identify possible specific risk factors to the general public., Methods: All incident cases of CJD were identified in the health area of Meixoeiro Hospital (187,877 inhabitants) over a 14-year period, 1997-2010, and classified according to WHO diagnostic criteria. We obtained clinical detail and epidemiological information on all cases. Crude and age-specific incidence rates were calculated. A review of surgical or invasive medical procedures was undertaken., Results: We diagnosed 12 patients with CJD, 10 sporadic CJD (sCJD), and two genetic CJD (gCJD). No iatrogenic or variant CJD was detected. According to Poisson distribution, 3.9 CJD cases would be expected for our area over the 14 years researched. The average yearly mortality rate from CJD was 4.6 cases per million (3.8 from sCJD and 0.8 from gCJD). Eight patients (67%) underwent at least one surgical or invasive medical procedure. Sixteen of twenty-seven (59%) of these procedures were undertaken in Meixoeiro Hospital., Conclusions: The incidence of CJD in the health area of Meixoeiro Hospital is three times higher than expected. The hypothesis that at least some cases of sCJD are apparently because of covert transmission or zoonosis events should not be formally refuted and might explain the high rate found., (© 2012 John Wiley & Sons A/S.)

This study gives the first record of Mugil hospes distributed in the Gulf of Mexico. This species previously has been confused with its congener Mugil curema and can be easily differentiated by the shape of the ctenii on their scales., (© 2011 The Authors. Journal of Fish Biology © 2011 The Fisheries Society of the British Isles.)

Introduction: Body weight is useful for many medical and nutritional procedures. When it is difficult or impossible to measure body weight in hospitalized/institutionalized elderly, it can be estimated through equations based on anthropometry generated in other countries, although their validity in other contexts has been poorly studied., Objectives: To create and validate an equation for estimating body weight for both, hospitalized and nursing home residents Mexican elderly women (institutionalized) using anthropometric measurements., Methods: A validation study was carried out in elderly women (> or = 60 years old), admitted to the Geriatrics Service of the Hospital Civil de Guadalajara "Fray Antonio Alcalde" during February-April 19th (n = 43) and April 20th-June 2005 (n = 29), and elderly women residing in three nursing homes in the Metropolitan Area of Guadalajara evaluated during June 2003-June 2004 (n = 23). Subjects were weighed using a scale which was adapted to their clinical situation and were anthropometrically assessed. In the first sample, we generated a new equation using multiple regression analyses. Then, the equation was validated in the other two samples. We also estimated weight using Chumlea's equations: in all samples, estimated and actual weights were compared between each other through a paired t-test. A p < 0.05 was considered as significant., Results: Mean ages in each sample were: 84.3 +/- 7.3, 84.4 +/- 9.1, and 84.2 +/- 8.5 years, respectively. Mean actual weights were: 48.2 +/- 13.5, 48.1 +/- 10.1, and 55.0 +/- 12.3 kg, respectively. The resulting equation was: estimated weight = (1.599* knee height) +(1.135* mid arm circumference) + (0.735*calf circumference) + (0.621* tricipital skinfold thickness)-83.123 (R2 = 0.896, p < 0.001). In hospitalized women, there were no significant differences between estimated and actual weight (sample 1:D-0.02 +/- 4.3 kg, p = 0.976; sample 2: D-0.7 +/- 4.2 kg, p = 0.352). In female nursing homes residents (institutionalized women) weight was significantly overestimated (1.9 +/- 3.2 kg p < 0.01), but the mean difference was smaller than the ones found using Chumlea's equations., Conclusions: The developed equation predicted accurately hospitalized elderly women's body weight in our context. In institutionalized elderly women, weight was significantly overestimated. It would be useful to derive equations for different settings.uals who present normal body weight.

Previous studies of the olive ridley Lepidochelys olivacea population structure in the tropical eastern Pacific have indicated the existence of a single panmictic population ranging from Costa Rica to Mexico. This information has been used to design specific management measures to conserve primary nesting beaches in Mexico. However, little is known about olive ridleys in the Baja California Peninsula, their northernmost reproductive limit, where recent observations have shown differences in nesting female behaviour and size of hatchlings relative to other continental rookeries. We used mtDNA control region sequences from 137 turtles from five continental and four peninsular nesting sites to determine whether such differences correspond to a genetic distinction of Baja California olive ridleys or to phenotypic plasticity associated with the extreme environmental nesting conditions of this region. We found that genetic diversity in peninsular turtles was significantly lower than in continental nesting colonies. Analysis of molecular variance revealed a significant population structure (Phi ST = 0.048, P = 0.006) with the inclusion of peninsular samples. Our results: (i) suggest that the observed phenotypic variation may be associated with genetic differentiation and reproductive isolation; (ii) support the recent colonization of the eastern Pacific by Lepidochelys; (iii) reveal genetic signatures of historical expansion and colonization events; and (iv) significantly challenge the notion of a single genetic and conservation unit of olive ridleys in the eastern Pacific. We conclude that conservation measures for olive ridleys in Mexico should be revised to grant peninsular beaches special attention.

To determine the effect of air pollution in Mexico City on respiratory health, patient visits for upper respiratory tract infections were monitored in five clinics. Levels of ozone, nitrogen dioxide, carbon monoxide, and sulfur dioxide, and climatological variables were collected. Correlations of filtered data revealed an association between NO2 and O3 with an increase in visits to clinics because of respiratory problems. Autoregressive analysis indicated that pollutant levels/respiratory visits associations remained significant even after simultaneous inclusion of temperature, suggesting that air pollution was associated with 10 to 16% of the clinic visits. The relative risk indicated that high levels of O3 and NO2 could increase the total number of clinic visits to between 19 and 43% above average. The other pollutants and the control group did not demonstrate significant associations.

In this intervention, participants design and implement an HIV/AIDS prevention project for Mexican homosexual men. The intervention is consistent with, and contributes to, empowerment theory because it enhances collective action, provides opportunities to develop knowledge and skills, creates needed resources, and includes shared control with professional and among participants. The intervention described provides an illustration of an empowering process and distinguishes itself from empowerment outcomes. An evaluation of the project is also described, but the outcomes were HIV/AIDS-related behaviors rather than psychological empowerment of the participants. The results suggest that the participants' HIV/AIDS knowledge and preventive behavior improved when compared to individuals who did not participate in the intervention. In addition, the intervention generated community change initiated by participants. Implications for designing interventions using an empowerment approach are discussed.

Little knowledge exists about AIDS and Human Immunodeficiency Virus (HIV) infection among Latin American gay males. In Latin America, sexual transmission from man to man is the leading cause of HIV infection. In Mexico, which ranks third in number of AIDS cases in the Americas, more than three-quarters of the cases are due to sexual transmission; among these cases, 35% and 23.7% are due to homosexual and bisexual male practices, respectively. A sample of 200 individuals from Juarez, Mexico, a city on the U.S. border, was interviewed. Information about their AIDS knowledge, sexual behavior, and condom use was obtained. Factory workers and individuals who meet sexual partners in the streets reported more sexual partners than workers in service or professional occupations and those who meet their partners in bars and discos. Number of sexual partners and respondents' age were inversely associated with condom use. Implications for HIV prevention are discussed.

The results of a survey based on a sample of 4,059 students attending intermediate and upper intermediate schools in Mexico City and its metropolitan area showed that the percentage of drug use "ever" by substance was the following: alcohol, 59; tobacco, 53.2; inhalants, 5.4; cannabis, 3.8; tranquilizers, 3.1; amphetamines, 2.7; sedatives, 1.3; opium, 0.91; LSD, 0.54; cocaine, 0.52; heroin, 0.29. Of the students reporting use "ever", the percentage reporting use of one of these substances "in the past months" ranged from 22.5 to 58.3. While there were more female students among the users of tranquilizers and stimulants, male students predominated among the users of other substances, with the difference being most pronounced among cannabis users. Older students were more involved with cannabis; in contrast, inhalants were more popular with younger students. The use of other substances varied little with age. Use of alcohol and cannabis was also most frequent among students of schools in middle, upper middle and upper class areas, whereas use of inhalants was most common among students attending schools in lower class areas.