Diagnostic value of glycoprotein band patterns of three serologic enzyme-linked immunoelectrotransfer blot assays for neurocysticercosis.

The enzyme-linked immunoelectrotransfer blot (EITB) assay to detect antibodies in serum is a complementary tool for the diagnosis of neurocysticercosis (NCC). Presence of at least one glycoprotein band corresponding to a Taenia solium (T. solium) antigen indicates a positive result; however, EITB assays have multiple glycoprotein bands, and previous work has suggested that band patterns may have additional diagnostic value. We included 58 participants with a definitive diagnosis of NCC who received care at the Instituto Nacional de Neurología y Neurocirugía in Mexico City. Three different EITB tests were applied to participants' serum samples (LDBio, France; US Centers for Disease Control and Prevention [CDC]; and Instituto de Diagnóstico y Referencia Epidemiológicos [InDRE]). There was substantial variability in specific glycoprotein band patterns among the three assays. However, in age- and sex-adjusted logistic regression models, the number of glycoprotein bands was positively associated with the presence of vesicular extraparenchymal cysts (InDRE adjusted odds ratio [aOR] 1.60 p < 0.001; CDC aOR 6.31 p < 0.001; LDBio aOR 2.45 p < 0.001) and negatively associated with the presence of calcified parenchymal cysts (InDRE aOR 0.63 p < 0.001; CDC aOR 0.25 p < 0.001; LDBio aOR 0.44 p < 0.001). In a sensitivity analysis also adjusting for cyst count, results were similar. In all three EITB serum antibody tests, the number of glycoprotein bands consistently predicted cyst stage and location, although magnitude of effect differed.

Statistical approach to Trichinella infection in horses handled by rural slaughterhouses across five distinctive socioeconomic regions in Mexico.

This work aimed to investigate the prevalence of Trichinella infection in horses (Equus ferus caballus) handled by rural slaughterhouses across five distinctive socioeconomic regions in Mexico. Serum samples were obtained by non-probabilistic convenience sampling in the Eastern, Southern Central and Western regions (100 samples of each). Additionally, muscle tissue samples were collected from the East (n=45), Southeastern (n=88), Southern Central (n=39) and Southwestern (n=11) regions. Antibodies were determined by Western blot and the muscle tissue was examined by artificial digestion. A global antibody prevalence of 2% was obtained. Regionally, a prevalence of 5% was observed in the East and 1% in the Southern Central region. No antibodies were detected in the West region and no larvae were found in the muscle tissue samples. These findings support the low presence of Trichinella in Mexican horses, which can positively impact the Mexican horse meat trade.

Immunodiagnosis of human neurocysticercosis: comparative performance of serum diagnostic tests in Mexico.

Immunodiagnosis has a supportive role in the diagnosis of neurocysticercosis (NCC). The aim of this study was to compare the validity of seven immunodiagnostic tests among serum samples from 58 patients with NCC, 26 patients with neurological diseases other than NCC, and 15 healthy controls. One test for viable parasite detection (HP10 antigen assay) and six for antibody detection were evaluated. For the entire sample, sensitivities ranged from 55.2% (NOVALISA) to 81.0% (enzyme-linked immunosorbent assay [ELISA] Taenia solium antibody), with the sensitivity of the latter test significantly higher than that of the in-house ELISA Taenia crassiceps, NOVALISA, enzyme-linked immunoelectrotransfer blot (EITB) CDC, and HP10. Overall, specificities were high, ranging from 85.4% (ELISA Ts) to 97.1% (NOVALISA), with no statistically significant differences. Detection of HP10 antigen was significantly associated with the presence of vesicular parasites. The simple and low-cost ELISA Taenia solium antibody Ab instead of EITB is recommended to support NCC diagnosis in both rural and hospital settings in Mexico.

Comparison of DOT-ELISA and Standard-ELISA for Detection of the Vibrio cholerae Toxin in Culture Supernatants of Bacteria Isolated from Human and Environmental Samples.

A comparison of DOT-ELISA and Standard-ELISA was made for detection of Vibrio cholerae toxin in culture supernatants of bacteria isolated from human and environmental samples. A total of 293 supernatants were tested in a double blind assay. A correlation of 100 % was obtained between both techniques. The cholera toxin was found in 20 Inaba and 3 Ogawa strains. Positive samples were from seafood (17 samples), potable water (1 sample) and sewage (5 samples). The DOT-ELISA was useful as the standard-ELISA to confirm the presence of cholera toxin in the environmental samples.

Influence of levamisole and Freund's adjuvant on mouse immunisation with antigens of adults of the liver fluke Fasciola hepatica Linnaeus, 1758.

We have studied the influence of both levamisole (AL) and Freund's adjuvant (AF) on the immunisation of mice with the secretory antigens of adults of the liver fluke Fasciola hepatica Linnaeus, 1758. Total IgG antibodies were detected in all groups where the F. hepatica antigen was administered, been levels of IgG1 increased respect to IgG2a antibodies. During immunisation, IL-4 and IFN-γ were only detected in AL and AF groups, but after infection, IL-4 boosted in all groups. IFN-γ increased two fold in AF and AL groups compared to the saline solution (AS) group. Worm recovering was of 32-35% in groups administered without antigen whereas in AS, AL and AF groups recovering was of 25%, 12% and 8%, respectively. Macroscopical lesions in the liver were scarce in AL and AF groups. Our data suggest that immunisation of mice with antigens of F. hepatica enhances the immune response avoiding both liver damage and worm establishment after challenge infection. The murine model of fasciolosis has appeared to be useful to elucidate the mechanism by which the parasite modulates immune responses toward a Th2 type but also the development of Th1 type-inducing vaccines.

Search for antibodies against Trichinella in two synanthropic Procyonidae species from southeast Mexico: white-nosed coatis (Nasua narica) and raccoons (Procyon lotor).

Trichinella is a nematode that are spread by the consumption of parasitized meat. Carnivora, a mammalian order, serve as key hosts for this parasite. However, evidence of Trichinella in wildlife from the Neotropics is extremely scarce, with reports documenting its presence only for five carnivore species: two Felidae, one Otariidae and two Mustelidae. Other widely distributed species that are consumed as bushmeat, such as Procyonidae, have not been studied in this context. A long-term study was performed for antibodies against Trichinella in coatis (Nasua narica) and common raccoons (Procyon lotor) in southeastern Mexico. Between the summer of 2009 to the winter 2013, a total of 291 coati samples and 125 raccoon samples were collected from a tropical green area located within an urban zone. An Enzyme-linked immunosorbent assay (ELISA) was used to detect antibodies against the excretory and secretory products of Trichinella spiralis muscle larva. ELISA-positive samples were further confirmed by Western Blot analysis. Results showed no evidence of antibodies during the first two years of study. However, in 2011, a sudden appearance of anti-Trichinella occurred. The seroprevalence reached its highest peak of 43% for coatis during winter 2013 and 53% for raccoons in summer 2013. This is the first study that provides evidence of Trichinella circulation within a neotropical procyonid community.

Serology survey of Ascaris suum and Trichinella spiralis in rural pigs in Southwestern Mexico.

BACKGROUND: Parasitic diseases of pigs are a public and veterinary health problem. Helminths influence pork production, whereas backyard pigs can transmit these parasites. OBJECTIVES: This work aimed to investigate the prevalence of antibodies against Ascaris suum and Trichinella spiralis in backyard pigs from Jamiltepec, Region de la Costa, Oaxaca, in Southwestern Mexico. METHODS: Six hundred sixty-four serum samples were obtained from backyard pigs from 23 rural villages distributed in 5 municipalities; samples were taken in a non-probabilistic manner with the owner's consent. The presence of serum antibodies against a total extract of A. suum adult worm was determined by ELISA. In contrast, antibodies to the excretion-secretion products of the T. spiralis muscle larva were determined by Western blot. RESULTS: The global seroprevalence for A. suum was 5.12% and 2.41% for T. spiralis; however, antibodies were only found in 8 villages and distributed in 3 municipalities. The highest frequency of positivity for Ascaris was found in the municipality of Santa Catarina Mechoacán (13.01%), whereas, in Santa María Huazalotitlán, the highest frequency of positivity for Trichinella was found (5.75%). In San Andrés, frequencies were 7.23% and 4.82%, respectively. No statistical differences were observed between populations. CONCLUSIONS: Our data suggest that helminth transmission is restricted by locality. However, further studies must be conducted to understand the factors limiting this transmission to promote pork meat production in parasite-free zones.

Isolation and identification of filamentous fungi and yeasts with zoonotic potential obtained from cattle egret (Bubulcus ibis) droppings.

The different microorganisms that make up the normal microbiota of birds can be present in different substrates such as the soil and other elements that make up the habitat. In the case of the cattle egret, the intestinal microbiota can change due to partially migratory habits. Thus, this study aimed to isolate and identified fungi and yeasts with zoonotic potential obtained from cattle egret (Bubulcus ibis) droppings settler in Tulancingo, Hidalgo, at Eastern economic zone of Mexico. Cattle egret droppings were collected for analysis, a total of 240 pool samples, which were spread on Sabouraud agar and incubated at 25.00 - 37.00 ˚C for 2 to 3 days. Filamentous fungi and yeast were identified by morphology and Lactophenol Blue staining or Chinese Ink stains. Filamentous fungi genera Mucor spp. (42.35%), Rhizopus spp. (26.71%); Penicillium spp. (13.35%); Paecilomyces spp. (11.40%); Scedosporium spp. (1.95%); and, from yeasts such as Cryptococcus spp. (2.29%); Rhodotorula spp. (1.95%) were identified. In this work, the presence of filamentous fungi genera and yeasts with zoonotic potential were isolated from droppings of cattle egret. The clinical presentation of fungal infections in humans can occur when immunosuppression is present or different predisposition factors are conjugated. The presence of birds and their dropping in anthropogenic activities is not a predisposing factor for the presentation of the disease in immunologically competent humans.

Taenia solium: Socioeconomic changes and prevalence evolution in four endemic communities in northwestern Mexico.

In Mexico, for the past 30 years, a continuous decrease in the incidence of clinical taeniosis/cysticercosis has been documented. This work aimed to determine the influence of improvement in socioeconomic conditions on the prevalence of Taenia solium in four endemic communities in northwestern Mexico. This study was carried out in two phases. First, documentary information (1989-2018) was collected about the prevalence of Theridion solium in the federal entity of Sinaloa State. Second, a pilot study was performed in four communities of Sinaloa, which had an endemic history of Taenia transmission. In each community, a risk factor questionnaire was applied, and serum and stool samples were collected for convenience in a non-probabilistic way. Anti-cysticercus antibodies and adult worm coproantigen were determined. The documentary analysis showed the incidence of taeniosis and cysticercosis to have decreased by 98 and 53%, respectively, while the human development index increased by 5% (1992-2017). Our data suggest that the risk of parasitic transmission is low, although female sex was a risk factor for reporting tremors or seizures (prevalence rate 2.1336, CI: 1.1821-3.8508) and background of tapeworm infection (prevalence rate 1.2893, CI: 0.9795-1.6972). No tapeworms or eggs were found while examining stool samples, but protozoa cysts were observed in four samples. Unexpectedly, only one of the 79 stool samples was positive for coproantigens. This positive result was confirmed in a second sample. However, the evaluation of a third sample was negative. No antibodies were found in human (n = 377) or pig (n = 69) samples. These data suggest parasite transmission has been interrupted and could be possibly associated with improving socioeconomic conditions. Further studies are needed to determine the real prevalence of zoonoses in Mexico.

Bullfrogs (Lithobates catesbeianus) as a Potential Source of Foodborne Disease.

In Mexico, bullfrogs (Lithobates catesbeianus) are produced as gourmet food. However, bullfrogs can be carriers of pathogens because the frogs' preferred living conditions occur in stagnant water. The present study aimed to identify bacteria that cause foodborne diseases or are associated with human diseases. For molecular identification, based on the sequential analysis by 16S rRNA or rpoD was conducted on all isolates obtained from bullfrog. A total of 91 bacterial isolates were obtained from bullfrogs; 14 genera and 23 species were identified, including Acinetobacter johnsonii 16.5%; Aeromonas media 14.3%; Aeromonas veronii 13.2%; Providencia rettgeri 7.7%; Citrobacter freundii 6.6%; Aeromonas caviae 4.4%; Aeromonas hydrophila and Elizabethkingia ursingii 3.3%; Pseudomonas stutzeri, Raoultella ornithinolytica, and Shewanella putrefaciens 2.2%; Acinetobacter guillouiae, Acinetobacter pseudolwoffii, Citrobacter portucalensis, Citrobacter werkmanii, Edwardsiella anguillarum, Klebsiella michiganensis, Kluyvera intermedia, Kocuria rosea, Myroides odoratimimus, Myroides odoratus, Proteus sp., and Proteus hauseri 1.1%. In this study, 49.4% of the isolates obtained cause foodborne disease, 19.8% are bacteria that play an important role in the spoilage of food, 5.5% of isolates have nosocomial significance, 13.2% of bacteria are considered to be pollutants of the ecosystem, and in the case of A. salmonicida and Edwardsiella anguillarum (12.1%) to have a negative impact on aquaculture. Acinetobacter pseudolwoffii and Citrobacter portucalensis have not been reported to cause disease. Lastly of these isolates, 97.8% (89/91) can cause disease by food consumption or by direct contact for immunocompromised persons. The presence of these bacteria in bullfrogs represents a significant problem for human health. There is evidence that these microorganisms are pathogenic and frogs may also be reservoirs.

Trichinella spiralis: monoclonal antibody against the muscular larvae for the detection of circulating and fecal antigens in experimentally infected rats.

In this work we search for antigens of Trichinella spiralis in sera and stool of rats experimentally infected. The kinetic of antibodies to excretory and secretory (ES) antigens of muscle larvae (ML) was also determined. Wistar rats were infected with 15 ML per gram of body weight and blood samples were collected weekly for 10 weeks. Antibodies were studied using an indirect ELISA. For detection of circulating antigens and coproantigens, a sandwich ELISA was developed with the use of polyclonal rabbit antibodies obtained against the total extract of ML and an IgM monoclonal antibody (Mab) against ES antigens of ML. No reactivity was observed between Mab and the total worm antigens of Angiostrongylus cantonensis, Ascaris suum, Echinococcus granulosus, Fasciola hepatica, Strongyloides stercoralis, Taenia solium, Toxocara canis and Trichuris trichiura. The IgM Mab recognized antigens of 45, 49, and 55 kDa in ES antigens and was unable to bind ES antigens deglycosylated with trifluoromethanesulphonic acid (TFMS) indicating that a glycan structure is present in the epitope recognized by this Mab. The sensitivity of sandwich ELISA was 1 ng/mL. Circulating antigens were detected in all infected rats between 3 and 8 weeks post infection and coproantigens were found during the first two days post infection. Antibodies were detected since the third week post infection through the end of experiment. These results suggested that antigen detection by our sandwich ELISA could be a useful complementary laboratory test for antibody detection.

Comparative effects of levamisole, Staphylococcus, and Freund's adjuvant on rat immunization with excretory and secretory antigens of Trichinella spiralis muscle larvae.

A comparison was made of the effects of levamisole, the bacterial fractions of Staphylococcus, and Freund's adjuvant on the immunization of rats with the excretory and secretory antigens of Trichinella spiralis muscle larvae. Wistar rats were immunized with the antigen and a saline solution, levamisole (LV), Staphylococcus (ST), or Freund's adjuvant (FA). After immunization, rats were infected, and the parasite burden at muscular phase was calculated for each group. Levels of IgG1 and IgG2 antibodies, as well as levels of two cytokines, IL-4 and IFN-γ, were evaluated during the immunization and postinfection periods. Differences were found in the kinetics of antibody production between groups (p < 0.01). In all cases, there was reactivity with the main 45-, 50-, and 55-kDa antigens of Trichinella muscle larvae. Immunization with FA and ST enhanced the production of IgG1, but only FA showed a significant increase in the production of IFN-γ (p < 0.01), resulting in 86% protection against the infection. In contrast, only 60-70% protection was attained in the ST and LV groups (p < 0.01). These data support the idea that levamisole and Staphylococcus can be used as adjuvant to enhance the humoral response and, at the same time, demonstrate that IFN-γ could be involved in protection against Trichinella.

Prevalence of Parasitic Infections with Zoonotic Potential in Tilapia: A Systematic Review and Meta-Analysis.

Tilapia has a high socioeconomic value in many countries worldwide. However, it has been identified as a zoonotic parasite reservoir. A systematic literature search and meta-analysis were carried out in order to estimate the global prevalence of zoonotic parasites that affect tilapia. The search was performed by three field experts to avoid reviewer bias. Polled prevalence was estimated using a logistic-normal random-effect regression model in the R software. We dealt with the heterogeneity among studies through subgroup analysis, taking into account the continent, country, genus of the host, parasite taxonomic group, sample origin, and type of diagnostic test as moderator variables. Fifty-two eligible articles were identified covering five tilapia genera with a pooled prevalence of 0.14 (95% CI: 0.10−0.20) showed significant heterogeneity (I2 = 98.4; p < 0.001). The subgroup analysis revealed that the most affected host was Sarotherodon, with a prevalence of 0.42 (95% CI: 0.22−0.65). Cestode was the taxonomic group with the largest prevalence (0.40; 95% CI:0.32−0.48), followed by amoeba (0.24; 95% CI: 0.16−0.35) and nematode (0.22; 95% CI: 0.11−0.38), among which, Schyzocotyle spp., Opistorchis spp., Gnathostoma spp. and Vermamoeba spp. have an impact on public health. Significant differences (p < 0.004) were found among continents and countries, with the highest value of prevalence detected in the African continent (0.28; 95% CI: 0.20−0.37), specifically in Tanzania (0.56; 95% CI: 0.22−0.87) and Egypt (0.43; 95% CI: 0.20−0.55). The origin of samples had a significant effect (p < 0.0001) on the detected prevalence, especially from those that showed the highest prevalence (0.24; 95% CI: 0.17−0.33). Finally, there were no differences in prevalence according to the diagnostic test (p = 0.97). Our results provide useful information on the development of epidemiological programs for the control of zoonoses associated with parasites in tilapia and in the design, planning, and implementation of future research.

Physicochemical Water Quality Influence on the Parasite Biodiversity in Juvenile Tilapia (Oreochromis spp.) Farmed at Valle Del Mezquital in the Central-Eastern Socioeconomic Region of Mexico.

Aquaculture parasite biodiversity dependents on multiple environmental characteristics, including water quality. The analysis of this relationship aims to support improvements in the production management of tilapia. For this purpose, a total of 100 juvenile fishes (Oreochromis spp.) and 30 water samples were collected at Valle del Mezquital in the Central-Eastern socioeconomical region of Mexico. A study of parasite biodiversity was carried out and water quality parameters were determined. Biodiversity in the habitat was measured using the Simpson diversity index, which considers the number of species present and the abundance of each one; we also calculate the Berger-Parker index to estimate the proportional importance of the most abundant species. In general, it was found that 86% of the examined specimens were parasitized. Parasite biodiversity was 11 genera (Simpson index = 0.55). Trichodina spp. (Ciliophora) was the dominant genus (Berger-Parker index = 0.51). The protozoa Apiosoma spp. was associated with the water hardness (Berger-Parker index = 0.57). Furthermore, the presence of monogeneans showed a positive correlation with the levels of nitrites and ammonium in the water (Berger-Parker index = 0.06-0.55). This characterization may represent a useful tool in the comprehensive management of parasites that affect the farmed tilapia. However, new data is necessary to expand the knowledge about the environment-host-parasite relationship.

FT-MIR and Raman spectroscopy coupled to multivariate analysis for the detection of clenbuterol in murine model.

A fast and simple screening method for the determination of clenbuterol at the ppb level in a murine model was demonstrated by Mid Infrared (MIR) and Raman spectroscopy in conjunction with multivariate analysis. In order to build the calibration models to quantify clenbuterol in rat meat, mixtures of rat meat and clenbuterol were prepared in a range of 5-10,000 ppb. Partial Least Square (PLS) analysis was used to build the calibration model. The results shown that Mid Infrared and Raman spectroscopy were efficient, but Mid Infrared (R(2) = 0.966 and SEC = 0.27) were superior to Raman (R(2) = 0.914 and SEC = 1.167). The SIMCA model developed showed 100% classification rate of rat meat samples with or without clenbuterol. The results were confirmed with contaminated meat samples from animals treated with clenbuterol. Chemometric models represent an attractive option for meat quality screening without sample pretreatments which can identify veterinary medicinal products at the ppb level.

Helminths of the Wild Boar (Sus scrofa) from Units of Conservation Management and Sustainable Use of Wildlife Installed in the Eastern Economic Region of Mexico.

Wild boars (Sus scrofa) were introduced in Mexico for sport hunting and meat trading for human consumption, but the available data regarding their role in pathogen transmission are limited. This research and field work aimed to identify the helminths of the wild boar produced in three units of conservation management and sustainable use of wildlife placed in the eastern economic region of Mexico. Samples of feces and serum were collected from 90 animals that came from three different ranches. Stool examination and antibody determination to Fasciola hepatica, Taenia crassciceps, Ascaris suum, Toxocara canis (ELISA), and Trichinella spiralis (Western blot) were performed. In addition, 30 diaphragm samples from one ranch were obtained for artificial digestion. Eggs of Strongyloides sp. (72.2%), Metastrongylus sp. (57.7%), Oesophagostomum sp. (53.3%), and Trichuris sp. (37.7%) were found in addition to oocysts of Eimeria sp. (75.6%). Antibodies to Fasciola (8.9%), Taenia (4.4%), Ascaris (32.2%), Toxocara (20%), and Trichinella (5.5%) were found. The eggs of Strongyloides and Oesophagostomum were associated to female hosts. One nematode larva was found by artificial digestion. This is the first report to identify helminths from wild boars in Mexico. In addition, this study identifies the potential risk of the wild boar as a transmission channel of parasites that can have an impact on public health.

Kinetics of Eosinophils during Development of the Cellular Infiltrate Surrounding the Nurse Cell of Trichinella spiralis in Experimentally Infected Mice.

We study the kinetics of eosinophils during the development of the cellular infiltrate surrounding the nurse cell of Trichinella spiralis (T. spiralis) in experimentally infected mice. Male CD1 mice were experimentally infected with 50 viable muscle larvae of the MSUS/MEX/91/CM-91 T. spiralis strain. Tongues and diaphragms were obtained daily from days 13 to 39 post infection. Diaphragms were compressed and subjected to Giemsa stain. Tongues were histologically sectioned and stained with erythrosine B or hematoxylin and eosin. The cellular infiltrate and the nurse cell-larva complex were detected by optical microscopy since day 16 post infection. The size of the larva increased exponentially during the course of the infection. The kinetics of eosinophils showed a multimodal trend, with a bimodal predominance. The maximum peaks were reached on days 21 and 27 post infection. The results of this study demonstrate that eosinophils occur abundantly in two transcendent moments of the T. spiralis life cycle: first, when the stage 1 larva invades the myocyte and second when the nurse cell-larva complex has been fully developed. These results help one to understand the immunobiology of T. spiralis, highlighting the importance of eosinophils in the survival of the larva in skeletal muscle. Further studies are needed to characterize the cell populations that comprise the cellular infiltrate during the development of the mother cell.

Comparative analysis of antibodies and lymphocytes in pulmonary tuberculosis patients with negative and positive cultures.

INTRODUCTION: The sputum smear or the culture are the definitive diagnosis of pulmonary tuberculosis. Only a fraction of clinical patients are culture-confirmed. METHODOLOGY: A total of 24 clinical cases (40 ± 14 years old) with positive smear and negative co-morbidity were studied. Cases were selected from 600 patients who attended the pneumology service over two years. A sputum sample was cultured in Löwenstein-Jensen medium with consequent amplification of the rrnA V2 promoter, the differentiation region 4, and the IS6110 insertion sequence of Mycobacterium tuberculosis. After the culture result, the patients were divided into negative (n = 14) or positive (n = 10) culture groups. In addition, 30 samples from healthy donors (45 ± 10 years) were studied. The numbers of CD4, CD8 and CD19 lymphocytes were determined by flow cytometry. Levels of IgA and IgG to M. tuberculosis were measured by ELISA. RESULTS: IgG and IgA levels were detected in patients with positive culture, while only IgA was found in patients with negative cultures. The lymphocyte populations in the two groups were similar.  The presence of a pleural apical cap was found more frequently in patients with negative- (57%) than with positive cultures (10%). CONCLUSIONS: The isotype profile in patients with positive cultures was both IgA and IgG positive, while in patients with negative culture, only IgA was found. The results will contribute to improve the diagnostic algorithm and appropriate treatment of patients with clinical tuberculosis. Further studies are needed to determine if this profile is predictive of the outcome of isolation.

Anthelmintic resistance in hair sheep farms in a sub-humid tropical climate, in the Huasteca Potosina, Mexico.

This is the first report about anthelmintic resistance (AR) in hair sheep farms determined in a sub-humid tropical climate, in an area known as Huasteca Potosina, Mexico. Faecal egg count reduction tests (FECRT) and egg hatch in vitro tests were conducted to identify the level of AR against benzimidazole (BZ) in parasitic gastrointestinal nematode (GIN) populations. An allele-specific polymerase chain reaction (AS-PCR) was performed to obtain a 250 bp band, indicating resistance, and a 550 bp band, indicating susceptibility to BZ. Macrocyclic lactones (ML) and imidazothiazole (IMZ) drugs were also tested with the FECRT. A PROBIT analysis was conducted using SAS to determine the 50% lethal doses (LD50) of the drugs according to the egg hatch in vitro test. Resistance to BZ and ML was found on all farms (0-70% effectiveness), whereas the susceptibility of nematodes to IMZ was detected with the FECRT (93-100% effectiveness). The LD50 was higher than the discriminating dose (0.1 µg ml-1) for BZ and confirmed AR to this anthelmintic; we also confirmed a high AR frequency with AS-PCR. Therefore, we suggest that strategic deworming should be performed to avoid the development of resistance to imidazothiazole.

Frequency of Helminth Eggs in Faeces of Puppies Living in Urban or Rural Environments of Mexico City.

BACKGROUND: The dog, Canis familiaris, a domestic animal that maintains close contact with humans and other animals, is considered as a potential source of zoonotic parasites. The current study aimed to determine the frequency of helminth eggs in feces of puppies of dog living in urban or rural environments of Mexico City between spring and summer of 2013. METHODS: Stool samples (n=180) were analyzed by sedimentation with formalin-ether. Samples were collected from puppies living in the urban zone (n=90; stray animals) or in the rural environment (n=90; stray animals, animals with owner and animals confined to a canine control center). RESULTS: Eggs of Toxocara canis (41%), Ancylostoma caninum (8%) and Dipylidium caninum (3%) were found in the rural environment but none in the urban zone. A frequency of 19% of Toxocara eggs was found in the canine control center, while, in stray puppies, the frequency was of 12% and 10% in animals with owner. Eggs of Toxocara were found in 33% samples of puppies with history of antiparasitic treatment. CONCLUSION: This study supports the observation of helminth population reduction in urban environments. Further studies are needed to identify the factors that affect the development and transmission of helminth eggs in urban environments.