Diversity of midgut microbiota in ticks collected from white-tailed deer (Odocoileus virginianus) from northern Mexico

Ticks host different pathogens as endosymbiont and nonpathogenic microorganisms and play an important role in reproductive fitness and nutrient provision. However, the bacterial microbiomes of white-tailed deer ticks have received minimal attention. This study aimed to examine the bacterial microbiome of ticks collected from Odocoileus virginianus on the Mexico-United States border to assess differences in microbiome diversity in ticks of different species, sexes, and localities. Five different tick species were collected: Rhipicephalus microplus, Dermacentor nitens, Otobius megnini, Amblyomma cajennense, and A. maculatum. The tick microbiomes were analyzed using next-generation sequencing. Among all tick species, the most predominant phylum was Proteobacteria, followed by Actinobacteria and Firmicutes. The ticks from Tamaulipas and Nuevo León presented the highest bacterial species diversity. Acinetobacter johnsonii and A. lwoffii were the common bacterial species in the microbiome of all ticks, Coxiella were present in R. microplus, and Dermacentor nitens also exhibited a Francisella-like endosymbiont. The microbiome of most females in D. nitens was less diverse than that of males, whereas R. microplus occurs in females, suggesting that microbiome diversity is influenced by sex. In the bacterial communities of A. maculatum and O. megnini, Candidatus Midichloria massiliensis, and Candidatus Endoecteinascidia fumentensis were the most predominant endosymbionts. These results constitute the initial report on these bacteria, and this is also the first study to characterize the microbiome of O. megnini.

In vitro anti-Trypanosoma cruzi activity of methanolic extract of Bidens pilosa and identification of active compounds by gas chromatography-mass spectrometry analysis

Chagas disease, caused by Trypanosoma cruzi parasite, is a significant but neglected tropical public health issue in Latin America due to the diversity of its genotypes and pathogenic profiles. This complexity is compounded by the adverse effects of current treatments, underscoring the need for new therapeutic options that employ medicinal plant extracts without negative side effects. Our research aimed to evaluate the trypanocidal activity of Bidens pilosa fractions against epimastigote and trypomastigote stages of T. cruzi, specifically targeting the Brener and Nuevo León strains-the latter isolated from Triatoma gerstaeckeri in General Terán, Nuevo León, México. We processed the plant's aerial parts (stems, leaves, and flowers) to obtain a methanolic extract (Bp-mOH) and fractions with varying solvent polarities. These preparations inhibited more than 90% of growth at concentrations as low as 800 μg/ml for both parasite stages. The median lethal concentration (LC50) values for the Bp-mOH extract and its fractions were below 500 μg/ml. Tests for cytotoxicity using Artemia salina and Vero cells and hemolytic activity assays for the extract and its fractions yielded negative results. The methanol fraction (BPFC3MOH1) exhibited superior inhibitory activity. Its functional groups, identified as phenols, enols, alkaloids, carbohydrates, and proteins, include compounds such as 2-hydroxy-3-methylbenzaldehyde (50.9%), pentadecyl prop-2-enoate (22.1%), and linalool (15.4%). Eight compounds were identified, with a match confirmed by the National Institute of Standards and Technology (NIST-MS) software through mass spectrometry analysis.

Impact of home improvements and health education on the transmission of Trypanosoma cruzi Chagas in a rural area of western Mexico

Chagas disease is one of the most important vector-borne diseases in Latin America. Instituting home improvement preventive measures and increasing health education contribute to successful control of the triatomine insect vector. The impact of home and road improvements and health education upon the inhabitants of 37 human dwellings in three small towns in western Mexico were studied. Initially, few house roofs were made of concrete and few walls were cement-lined. Almost all houses initially lacked metal window screens and none used barbed wire fences. One year after the intervention, all of these measures were more common, and almost 100% of houses continued to use window screens and barbed wire fences ten years post-intervention. By ten years post-intervention, >75% of houses had cement-lined walls. Initially, 24.3% of human dwellings were infested with Triatoma longipennis Usinger; at one and ten years post-intervention, only 2.7% of dwellings were infested. The abundance of peridomestic opossums decreased after intervention and remained low ten years later. Approximately 10% of dogs were infected in both surveys. Human infections decreased from 2.98% to zero by 13 years post-intervention. Implementation of these intervention measures led to the successful control of Trypanosoma cruzi Chagas transmission in these towns.

Draft genome sequences of Bacillus pumilus 36R ATNSAL and B. safensis 13L LOBSAL, two potential candidate probiotic strains for shrimp aquaculture

OBJECTIVES

This work aimed to isolate bacterial strains with antagonist activity against Vibrio parahaemolyticus, the causative agent of acute hepatopancreatic necrosis disease (VP_AHPND) that was isolated from outbreaks in Mexico. Here, we report the draft genome sequences of two antagonistic strains, isolated from saline sediment in Sonora, Mexico.

METHODS

Cross-streak and well diffusion tests were employed to find the bacterial strains with higher inhibitory activity against VP_AHPND. The whole genomes of B. pumilus 36R ATNSAL and B. safensis 13L LOBSAL were sequenced using Ion Torrent^TM (PGM) and Illumina Miseq^TM platforms, respectively. Annotation was performed using the RAST server, and the genes involved in the biosynthesis of bacterial secondary metabolites were predicted using antiSMASH.

RESULTS

Two bacterial isolates, B. safensis 13L LOBSAL and B. pumilus 36R ATNSAL, were chosen based on their strong antagonistic profiles. The genome of 36R ATNSAL was 3.94 Mbp in length and contained 3824 genes and a total of 4116 coding sequences (CDSs); the genome of 13L LOBSAL was 3.68 Mbp and contained 3619 genes and 3688 CDSs. Twenty-eight and 32 biosynthetic gene clusters responsible for putative antimicrobial metabolite production were identified in 36R ATNSAL and 13L LOBSAL, respectively.

CONCLUSIONS

The two strains 13L LOBSAL and 36R ATNSAL showed excellent probiotic profiles in vitro. The genome sequences will help with the mining and reconstruction of metabolic pathways in Bacillus strains. Genome sequence-guided strain improvement could augment the probiotic potential of Bacillus strains for applications in shrimp aquaculture.

[Anti-Trypanosoma cruzi antibodies in Latin American migrants in transit through the México- USA border]

INTRODUCTION

In recent years, American trypanosomiasis has become an emergent public health problem in countries receiving migrant populations such as México, USA, Canada or those in Europe.

OBJECTIVE

To analyze the prevalence of anti-Trypanosoma cruzi antibodies in Latin American migrants on their way to USA and Canada by means of serological techniques.

MATERIAL AND METHODS

ELISA and IHA were performed to detect anti-T. cruzi antibodies. Also, each participant filled out a socioeconomic questionnaire to determine the associated factors with seropositive cases, which could facilitate the transmission in the migrants' country of origin.

RESULTS

Total seroprevalence among the studied population was 20% (24/120). The highest prevalence was found in migrants from Guatemala with 37.5% (6/16), followed by Honduras (22.6%; 12/53), El Salvador (16%; 4/25), and México (8.7%, 3/23). From the total 120 surveyed migrants, 105 (87.5%) recognized the vector of Chagas' disease, and 62 (59%) assured having been bitten by it. Highly significant statistical associations were found between infection and the construction materials for walls and the presence of pets (dogs) inside houses (p≤0.01), as well as with the building materials for backyards, inadequate basic services, and animal breeding inside corrals built around dwellings (p≤0.05).

CONCLUSION

Non-endemic countries receiving migrants from endemic areas should enhance or develop better health policies to prevent transfusion-transmitted Chagas or congenital parasite transmission.

Prevalence of Trypanosoma cruzi infection in dogs and small mammals in Nuevo León, Mexico

Chagas disease, caused by the protozoan Trypanosoma cruzi, is an important public health concern in areas extending from South America northward into the southern United States of America. Although this hemoflagellate has many wild and domestic mammalians reported as reservoir hosts, studies on this subject are scarce in Nuevo León state, a region located in northeastern Mexico. This cross-sectional study showed that the general prevalence of T. cruzi infection in Nuevo León state was 14.5% (35/241), this percentage matching the ones determined by PCR and traditional diagnostics. Localities and infected mammals did not significantly differ (χ²=6.098, p=0.192); however the number of infected animals was highly correlated with mammalian species (p=0.009). Striped skunks (Mephitis mephitis) were found to be the most infected overall (11/34, 32.3%), while dogs (Canis familiaris) had the lowest prevalence. In conclusion, although the prevalence of T. cruzi infection in small mammals was lower in Nuevo León than in other states of Mexico, our results provide new locality records, including striped skunks, opossums (Didelphis marsupialis) and dogs, and extend the recorded area to woodrats (Neotoma micropus).

Trypanosoma cruzi seroprevalence in pregnant women and screening by PCR and microhaematocrit in newborns from Guanajuato, Mexico

Chagas disease is caused by an infection with the protozoan hemoflagellate Trypanosoma cruzi, and it is a major endemic health problem in Latin America. The congenital route is one of the main non-vectorial pathways of transmission, which can arise either in the chronic or acute phase of maternal infection. Serological screening of T. cruzi infection was performed in 520 pregnant women and newborns at the Hospital General Regional de León, Guanajuato, Mexico, between 2014 and 2015. Anti-T. cruzi antibodies were detected in 20 mothers (4%) by ELISA and HIA with four PCR-positive newborn cases. Risk factors were identified according to an epidemiological survey, and the most significant (P<0.050) factors associated with T. cruzi infection were the building materials of dwellings, the presence of pets and dwellings located in rural areas. This study constitutes the first systematic study on congenital Chagas disease and the epidemiological risk factors in Guanajuato. Our results represent the probability of an incidence of 770 cases per 100,000 births during a period of 12 months, with a vertical transmission rate by 0.8%, which highlights the necessity to establish reliable serological and PCR tests in pregnant women to prevent vertical transmission. However, it is also important to follow-up the newborns from seropositive mothers for one year, which is necessary, as many children yielded negative results.

Association of Trypanosoma cruzi infection with risk factors and electrocardiographic abnormalities in northeast Mexico

BACKGROUND

American trypanosomiasis is a major disease and public health issue, caused by the protozoan parasite Trypanosoma cruzi. The prevalence of T. cruzi has not been fully documented, and there are few reports of this issue in Nuevo Leon. The aim of this study was to update the seroprevalence rate of T. cruzi infection, including an epidemiological analysis of the risk factors associated with this infection and an electrocardiographic (ECG) evaluation of those infected.

METHODS

Sera from 2,688 individuals from 10 municipalities in the state of Nuevo Leon, Mexico, were evaluated using an enzyme-linked immunosorbent assay and an indirect hemagglutination assay. An ECG case-control study was performed in subjects seropositive for T. cruzi and the results were matched by sex and age to seronegative residents of the same localities. A univariate analysis with χ2 and Fisher's exact tests was used to determine the association between seropositivity and age (years), sex, and ECG changes. A multivariate analysis was then performed to calculate the odd ratios between T. cruzi seropositivity and the risk factors.

RESULTS

The seropositive rate was 1.93% (52/2,688). In the ECG study, 22.85% (8/35) of the infected individuals exhibited ECG abnormalities. Triatoma gerstaeckeri was the only vector reported. The main risk factors were ceiling construction material (P ≤ 0.0024), domestic animals (P ≤ 0.0001), and living in rural municipalities (P ≤ 0.0025).

CONCLUSIONS

These findings demonstrate a 10-fold higher prevalence of Chagas disease than previously reported (0.2%), which implies a serious public health threat in northeastern Mexico. The epidemiological profile established in this study differs from that found in the rest of Mexico, where human populations live in close proximity to domiciliary triatomines.

Distribution of ixodid ticks on dogs in Nuevo León, Mexico, and their association with Borrelia burgdorferi sensu lato

This study aimed to document the geographic distribution of Ixodes tick species in dogs and the prevalence of Borrelia burgdorferi s.l. in adult ticks and blood samples by amplification of the ospA region of the B. burgdorferi genome. The study area included nine localities in Nuevo León state. DNA amplification was performed on pools of ticks to calculate the maximum likelihood estimation (MLE), and the community composition (prevalence, abundance, and intensity of infestation) was recorded. A total of 2,543 adult ticks, representing four species, Rhipicephalus sanguineus, Dermacentor variabilis, Rhipicephalus (Boophilus) annulatus, and Amblyomma cajennense, were recorded from 338 infested dogs. Statistically significant correlations were observed between female dogs and infestation (P = 0.0003) and between R. sanguineus and locality (P = 0.0001). Dogs sampled in Guadalupe and Estanzuela were positive by PCR (0.9 %) for B. burgdorferi. Rhipicephalus sanguineus had the highest abundance, intensity, and prevalence (10.57, 7.12 and 94.6, respectively). PCR results from 256 pools showed that four pools were positive for D. variabilis (1.6 %), with an MLE of 9.2 %; nevertheless, it is important to consider that in the area under examination probably other reservoir hosts for D. variabilis and B. burgdorferi are present that, very likely, play a much more important role in the ecology of Lyme borreliosis than dogs, which could be considered in future studies.

Nucleotide sequence variations of the major structural proteins (VP15, VP19, VP26 and VP28) of white spot syndrome virus (WSSV), a pathogen of cultured Litopenaeus vannamei in Mexico

White spot syndrome virus (WSSV) was first reported in farmed Litopenaeus vannamei stocks in Sinaloa and Sonora, Mexico during 1999 and continues to cause severe shrimp losses. WSSV genes encoding nucleocapsid (VP26 and VP15) and envelope proteins (VP19 and VP28) of a Mexican isolate were cloned in the pMosBlue vector. The nucleotide sequences of these genes were compared with WSSV isolates in GenBank. VP15 is highly conserved, and VP26 showed 99% homology to a Chinese isolate. The VP28 fragment demonstrated 100% homology to the majority of the isolates analysed (UniProt accession no. Q91CB7), differing from two Indian WSSV and one Chinese WSSV isolates by two non-conserved and one conserved replacements, respectively. Because of their highly conserved nature, these three structural proteins are good candidates for the development of antibody-based WSSV diagnostic tools or for the production of recombinant protein vaccines to stimulate the quasi-immune response of shrimp. In contrast, VP19 of the Mexican isolate was distinguishable from almost all isolates tested, including an American strain of WSSV (US98/South Carolina, GenBank accession no. AAP14086). Although homology was found with isolates from Taiwan (GenBank accession no. AAL89341) and India (GenBank accession no. AAW67477), VP19 may have application as a genetic marker.

[Trypanosoma cruzi in triatomines from Nuevo Leon, Mexico]

OBJECTIVE

To determine the prevalence of Trypanosoma cruzi in triatomines from Nuevo León using the standardization of an improved enzyme-linked immunosorbent assay test.

MATERIALS AND METHODS

From July to September 2005, 52 triatomines were captured in General Terán, a municipality located in Nuevo León. They were analyzed using optical microscopy (OM) and a polymerase chain reaction (PCR), as standards of reference, to develop a technique for detecting the parasite using enzyme-linked immunosorbent assay (ELISA).

RESULTS

Using OM and PCR, 31 triatomines were found to be positive and 21 negative. Using ELISA, 27 samples were identified as positive and 25 negative (specificity 100%, sensitivity 87%, negative predictive value 84%, and positive predictive value 100%). The prevalence of infected triatomines was 59.61% with OM and PCR, and 51.92% with ELISA. Our data confirm that the ELISA assay in triatomines is a fast, reliable and useful tool.

CONCLUSIONS

Since it was possible to simultaneously analyze a large number of samples with high sensibility and specificity values, the ELISA test proves to be useful for new epidemiologic studies having a high number of vectors. It is also less expensive than PCR. It is therefore recommended for epidemiological and preventive surveillance programs as a first screening test before conducting a confirmatory test using PCR.