Interaction between bacterial microbiota and nematode parasite communities in sheep's gastrointestinal tract.

The economic impact of gastrointestinal (GI) nematode infections on livestock production is well documented worldwide. Increasing evidence supports the hypothesis that parasite colonization induces significant changes in the GI tract environment and, therefore, in the landscape where the microbiota and parasites occur. Understanding the interactions between bacterial and parasite populations in the digestive tract of livestock may be useful to design parasite control strategies based on microbiota modification. The aims of this work were to investigate the impact of the oxytetracycline-mediated manipulation of the gut microbial community on the composition of GI nematode populations in naturally infected sheep and to explore changes in the GI microbial communities after nematode population treatment with the anthelmintic compound monepantel. Extensive manipulation of the GI microbiota with a therapeutic dose of the long-acting oxytetracycline formulation did not induce significant changes in the GI nematode burden. The gut microbiota of treated animals returned to control levels 17 days after treatment, suggesting strong resilience of the sheep microbial community to antibiotic-mediated microbiota perturbation. A significant decrease of the bacterial Mycoplasmataceae family (Log2FC = -4, Padj = 0.001) and a marked increase of the Methanobacteriaceae family (Log2FC = 2.9, Padj = 0.018) were observed in the abomasum of sheep receiving the monepantel treatment. While a comprehensive evaluation of the interactions among GI mycoplasma, methanobacteria and nematode populations deserves further assessment, the bacteria-nematode population interactions should be included in future control programs in livestock production. Understanding how bacteria and parasites may influence each other in the GI tract environment may substantially contribute to the knowledge of the role of microbiota composition in nematode parasite establishment and the role of the parasites in the microbiota composition.

Computer vision syndrome and associated factors in university students and teachers in Nampula, Mozambique.

BACKGROUND: Computer Vision Syndrome (CVS) is a complex of eye and visual problems that arise while using a computer or other Video Display Terminal (DVT). With the advent of the COVID-19 pandemic, the use of these DVTs has become indispensable in the lives of students and teachers. This study aims to identify the prevalence of CVS and associated factors in students and teachers at Lúrio University, in Nampula, during the pandemic period. METHODS: This is a cross-sectional study, carried out between November 2020 and March 2021. The validated CVS questionnaire (CVS-Q) and another semi-structured questionnaire on ergonomic risk factors were applied. Odds ratios (OR) and adjusted odds ratios (aOR) were calculated to measure the association between CVS and computer use conditions. RESULTS: The prevalence of CVS was 76.6%, and the female gender, age ≤ 20 years, levels I, II, III of course, lack of knowledge about ergonomics, use the computer to study, use more than 6 hours daily, absence of anti-reflex treatment, use of other devices and sitting in an inappropriate chair were risk factors for the occurrence of CVS, while being a teacher was a protective factor. CONCLUSION: The prevalence of CVS found in this study was high, due to several factors, especially not using ergonomic principles when using computers and other DVTs. There is a need to adopt intervention strategies focused on the most vulnerable groups such as women, age group ≤20 years and students, especially at the first year level, right after entering the University.

Assessment of the distribution of human and material resources for eye health in the public sector in Nampula, Mozambique.

BACKGROUND: The unavailability of human and material resources can affect access to eye health services, constituting an obstacle in the fight against avoidable visual impairment. This study aimed to assess the availability and distribution of human and material resources for eye health in the public sector in Nampula province. METHODS: A mixed method approach was used, which included document reviews (to extract information regarding the number of professionals and inhabitants in each district) and application of a questionnaire to heads of the ophthalmology department in each health facility (to obtain the list of available equipment). The ratios of eye health professionals per population in Nampula province and each of its districts were calculated and evaluated taking into account the recommendations of the World Health Organization (WHO). Based on the level of care of each health facility, the availability of equipment was evaluated. RESULTS: Nampula Province has not reached the recommended ratio of eye health professionals per population in the different categories (ophthalmic technicians with 0.8 per 100 thousand inhabitants; optometrists and ophthalmologists with 0.4 and 0.2 per 250 thousand inhabitants, respectively). Most districts of Nampula did not reach the recommended ratio in the three categories of professionals, except Nampula City (provincial capital). However, there was a greater concentration of professionals and facilities with eye health services in the provincial capital. Primary and secondary level health facilities lacked some equipment to provide eye health services within their scope. CONCLUSIONS: There is an unequal distribution of the workforce in Nampula and the centralization of surgical services at the Central Hospital of Nampula level. Therefore, there is a need to review resource distribution strategies and decentralization policy of eye health services in Nampula.

Monepantel-based anthelmintic combinations to optimize parasite control in cattle.

Improvement in the use of existing anthelmintics is a high priority need for the pharmaco-parasitology research field, considering the magnitude and severity of anthelmintic resistance as an important issue in livestock production. In the work described here, monepantel (MNP) was given alone or co-administered with either macrocyclic lactone (ML) or benzimidazole (BZ) anthelmintics to calves naturally infected with ML- and BZ-resistant gastrointestinal (GI) nematodes on two different commercial cattle farms. Both pharmacokinetic (PK) and efficacy assessments were performed. On Farm A, male calves (n = 15 per group) were treated with either MNP orally (2.5 mg/kg), IVM s.c. (0.2 mg/kg), ricobendazole (RBZ) s.c. (3.75 mg/kg) or remained untreated. On Farm B, eight groups (n = 15) of male calves received treatment with either: MNP, abamectin (ABM, oral, 0.2 mg/kg), RBZ (s.c., 3.75 mg/kg), albendazole (ABZ, oral, 5 mg/kg), MNP+ABM, MNP+RBZ, MNP+ABZ (all at the above-mentioned routes and doses) or remained untreated. Seven animals from each treated group (Farm B) were randomly selected to perform the PK study. MNP and its metabolite monepantel sulphone (MNPSO2) were the main analytes recovered in plasma after HPLC analysis. The combined treatments resulted in decreased systemic exposures to MNP parent drug compared with that observed after treatment with MNP alone (P < 0.05). However, the systemic availability of the main MNP metabolite (MNPSO2) was unaffected by co-administration with either ABM, RBZ or ABZ. Efficacies of 98% (Farm A) and 99% (Farm B) demonstrated the high efficacy of MNP given alone (P < 0.05) against GI nematodes resistant to ML and BZ in cattle. While the ML (IVM, ABM) failed to control Haemonchus spp., Cooperia spp. and Ostertagia spp., MNP achieved 99% to 100% efficacy against those nematode species on both commercial farms. However, MNP alone failed to control Oesophagostomum spp. (60% efficacy) on Farm A. The co-administered treatments MNP+ABZ and MNP+RBZ reached a 100% reduction against all GI nematode genera. In conclusion, the oral treatment with MNP should be considered to deal with resistant nematode parasites in cattle. The use of MNP in combination with BZ compounds could be a valid strategy to extend its lifespan for use in cattle as well as to reverse its poor activity against Oesophagostomum spp.

Assessment of cataract surgery outcomes in Nampula (Mozambique): visual acuity, visual function and quality of life.

BACKGROUND: Despite advances in surgical techniques, cataract remains the leading cause of preventable blindness, and massive surgeries have been adopted as a strategy to change this situation. Monitoring the results of cataract surgeries has become imperative to ensure their quality. Therefore, this study aims to assess the cataract surgery outcomes performed at the Central Hospital of Nampula Mozambique. METHODS: This is a prospective and longitudinal study in which translation, cultural adaptation and validation of the visual function (VF) and quality of life (QoL) questionnaire were performed. The appearance, content, construct, criterion, internal consistency and responsiveness were validated using the most common methods and indicators. Visual acuity (VA), VF and QoL were evaluated on 447 patients before and after surgery by t-test and effect sizes. RESULTS: VF and QoL questionnaires showed one-dimension, good values of TLI (0.973, 0.951) and SRMR (0.057, 0.054), and for each item, weights > 0.7, H2 > 0.5, ranges > 5.8 and the RMSEA < 0.08. Correlations for criterion validity were high and for responsiveness were high for QoL and moderate for VF one and the ordinal Cronbach's alpha coefficients were greater than 0.97. Difference between VA, VF and QoL before and after surgery was statistically significant (p < 0.001). After surgery, 74.3% of patients had good, 23.5% had borderline and 2.2% had poor VA. CONCLUSIONS: The cataract surgery outcomes are outside the WHO recommendations regarding VA, but they have had a great impact on improving VF and QoL. The questionnaires showed excellent psychometric properties and should be used in daily clinical practice to evaluate the results of cataract surgeries.

ABC-transporter gene expression in ivermectin-susceptible and resistant Haemonchus contortus isolates.

Mammalian efflux transporters of the ATP-binding cassette (ABC) regulate cellular levels of endo- and xenobiotics by transporting molecules across cell membranes and are involved in diverse biological processes. Over-expression of these ABC transporters has been involved in macrocyclic lactone resistance. The main goal of this work was to compare the gene expression of the whole ABC-transporter superfamily in isolates of the sheep nematode Haemonchus contortus with different degrees of susceptibility to ivermectin (IVM). Additionally, the effects of in vivo IVM treatment were evaluated in the resistant isolates. Parasite-free Corriedale lambs were artificially infected with either IVM-susceptible or IVM-resistant H. contortus isolates. The differential expression of ABC transcripts in H. contortus female worms with differential susceptibility to IVM were assessed by RNA-seq. Additionally, the transcription levels of ABC-transporter genes in IVM-resistant adult worms recovered from treated sheep at 12 and 24 h after IVM administration were compared to those of IVM-R worms collected from untreated sheep. The comparative analysis of the ABC-transcripts revealed some minor differences in the expression levels of HCON_00042800 (pgp-3), HCON_00020200.mod (ced-7c), HCON_00085890 (abt-4), HCON_00063000 (pmp-5) and HCON_00116670 (wht-8), indicating that, at transcriptional level, these ABC-genes alone cannot explain resistance in H. contortus. HCON_00130060 (pgp-9.2) was highly differentially expressed in resistant isolates compared to susceptible ones, which agrees with previous reports suggesting that pgp-9 may be one of the most relevant candidates contributing to the multi-genic nature of the IVM resistance trait.

Pharmacokinetics and milk excretion pattern of eprinomectin at different dose rates in dairy cattle.

This study aimed at determining the plasma disposition kinetics of eprinomectin (EPM) and EPM excretion pattern through milk after topical administration to dairy cattle at the recommended dose of 0.5 mg/kg and at 1 and 1.5 mg/kg. A high variability in the plasma concentration profiles was observed among animals, particularly in the Cmax values, with a coefficient of variation between 39 and 53%. The Cmax and AUC values were significantly affected by the dose administered at 1.5 mg/kg. However, such differences did not seem to follow a linear pattern among treatments. These parameters did not differ among dose rates after dose normalization; nevertheless, the simulation of a linear kinetic disposition showed a mean plasma AUC value of 254 ng.d/ml instead of the observed value of 165 ng.d/ml. EPM concentration profiles in milk were significantly lower than those measured in plasma. The Cmax and AUC milk-to-plasma ratios ranged from 0.14 to 0.26 and 0.16 to 0.21, respectively (p>0.05). The low milk-to-plasma ratio of EPM accounted for a low percentage of the fraction of the administered dose excreted through milk, being significantly higher at a dose rate of 0.5 mg/kg (0.07%) of EPM than at 1.5 mg/kg (0.04%) (p<0.05). The topical administration of EPM to lactating dairy cows at higher doses than that recommended for gastrointestinal nematodes showed a milk excretion pattern with a zero milk withdrawal period. In conclusion, the administration of topical EPM formulation at 1 or 1.5 mg/kg may be a valuable tool to be used in regional strategic deworming programs aimed to control ectoparasite infections in dairy production systems.

Ivermectin Pharmacokinetics, Metabolism, and Tissue/Egg Residue Profiles in Laying Hens.

The goals were to determine the ivermectin (IVM) plasma pharmacokinetics, tissue and egg residue profiles, and in vitro metabolism in laying hens. Experiments conducted were (1) 8 hens were intravenously treated with IVM and blood samples taken; (2) 88 hens were treated with IVM administered daily in water (5 days) (40 were kept and their daily eggs collected; 48 were sacrificed in groups (n = 8) at different times and tissue samples taken and analyzed); (3) IVM biotransformation was studied in liver microsomes. Pharmacokinetic parameters were AUC = 85.1 ng·day/mL, Vdss = 4.43 L/kg, and T1/2el = 1.73 days. Low IVM tissue residues were quantified with the highest measured in liver and skin+fat. IVM residues were not found in egg white, but significant amounts were quantified in yolk. Residues measured in eggs were greater than some MRL values, suggesting that a withdrawal period would be necessary for eggs after IVM use in laying hens.

Integrated assessment of ivermectin pharmacokinetics, efficacy against resistant Haemonchus contortus and P-glycoprotein expression in lambs treated at three different dosage levels.

The main goals of the current work were: (a) to assess the ivermectin (IVM) systemic exposure and plasma disposition kinetics after its administration at the recommended dose, x5 and x10 doses to lambs, (b) to compare the clinical efficacy of the same IVM dosages in lambs infected with an IVM-resistant isolate of Haemonchus contortus, and (c) to assess the expression of the transporter protein P-glycoprotein (P-gp) in H. contortus recovered at 14 days after administration of the IVM dose regimens. There were two separated trials where IVM was administered either subcutaneously (SC, Experiment I) or intraruminally (IR, Experiment II). Each experiment involved twenty-four (24) lambs artificially infected with a highly resistant H. contortus isolate. Animals were allocated into 4 groups (n=6) and treated with IVM at either 0.2 (IVM x1), 1 (IVM x5) or 2mg/kg (IVM x10). Plasma samples were collected up to 12 days post-treatment and analysed by HPLC. An untreated-control Group was included to assess the comparative anthelmintic efficacy of the different treatments. The level of expression of Pgp in H. contortus specimens obtained from lambs both untreated and IR treated with the different IVM doses was quantified by real time PCR. Parametric and non-parametric tests were used to compare the statistical significance of the results (P<0.05). After the SC treatment, the IVM plasma area under the concentration-time curve (AUC0-LOQ) increased from 41.9 (IVM SCx1) up to 221 (IVM SCx5) and 287 (IVM SCx10)ng.day/mL and after the IR treatment from 20.8 (IVM IRx1) up to 121 (IVM IRx5) and 323 (IVM IRx10)ng.day/mL. Dose-adjusted AUC0-LOQ and Cmax were similar among doses, demonstrating dose proportionality for IVM after both SC and IR administration at the three different doses. The efficacies against resistant H. contortus after the SC treatment were 42% (IVM SC1), 75% (IVM SCx5) and 75% (IVM SCx10). However, the IR IVM treatment reached clinical efficacies ranging from 48% (IVM IRx1) up to 96% (IVM IRx5) and 98% (IVM IRx10). None of the IR IVM treatments increased the expression of P-gp in adult H. contortus at 14 days post-treatment compared to samples collected from the untreated control group. An enhanced parasite exposure of the drug at the abomasum may explain the improved efficacy against this recalcitrant H. contortus isolate observed only after the IR administration at 5- and 10-fold the IVM therapeutic dosage.

Comparative tissue pharmacokinetics and efficacy of moxidectin, abamectin and ivermectin in lambs infected with resistant nematodes: Impact of drug treatments on parasite P-glycoprotein expression.

The high level of resistance to the macrocyclic lactones has encouraged the search for strategies to optimize their potential as antiparasitic agents. There is a need for pharmaco-parasitological studies addressing the kinetic-dynamic differences between various macrocyclic lactones under standardized in vivo conditions. The current work evaluated the relationship among systemic drug exposure, target tissue availabilities and the pattern of drug accumulation within resistant Haemonchus contortus for moxidectin, abamectin and ivermectin. Drug concentrations in plasma, target tissues and parasites were measured by high performance liquid chromatography. Additionally, the efficacy of the three molecules was evaluated in lambs infected with resistant nematodes by classical parasitological methods. Furthermore, the comparative determination of the level of expression of P-glycoprotein (P-gp2) in H. contortus recovered from lambs treated with each drug was performed by real time PCR. A longer persistence of moxidectin (P < 0.05) concentrations in plasma was observed. The concentrations of the three compounds in the mucosal tissue and digestive contents were significant higher than those measured in plasma. Drug concentrations were in a range between 452 ng/g (0.5 day post-treatment) and 32 ng/g (2 days post-treatment) in the gastrointestinal (GI) contents (abomasal and intestinal). Concentrations of the three compounds in H. contortus were in a similar range to those observed in the abomasal contents (positive correlation P = 0.0002). Lower moxidectin concentrations were recovered within adult H. contortus compared to abamectin and ivermectin at day 2 post-treatment. However, the efficacy against H. contortus was 20.1% (ivermectin), 39.7% (abamectin) and 89.6% (moxidectin). Only the ivermectin treatment induced an enhancement on the expression of P-gp2 in the recovered adult H. contortus, reaching higher values at 12 and 24 h post-administration compared to control (untreated) worms. This comparative pharmacological evaluation of three of the most used macrocyclic lactones compounds provides new insights into the action of these drugs.

In vivo and ex vivo assessment of the interaction between ivermectin and danofloxacin in sheep.

The impact of an efflux pump-related interaction between ivermectin and danofloxacin on their intestinal transport (ex vivo) and disposition kinetics (in vivo) was assessed. Eighteen male Corriedale sheep were randomly assigned to one of three groups. Animals in Group A received 0.2mg/kg ivermectin by SC injection, those in Group B were given 6 mg/kg danofloxacin SC on two occasions 48 h apart and those in Group C were treated with both compounds at the same rates. Plasma concentrations of ivermectin and danofloxacin were measured by HPLC using fluorescence detection. Ex vivo intestinal drug transport activity was measured by the use of the Ussing chamber technique. Plasma concentrations of ivermectin in the first 6 days after injection tended to be higher in Group C than Group A. Contemporaneous treatment with ivermectin significantly increased systemic exposure to danofloxacin (AUC values were 32-35% higher) and prolonged the elimination half-life of danofloxacin (40-52% longer). Ex vivo, incubation with ivermectin significantly decreased the efflux transport of rhodamine 123, a P-glycoprotein substrate, in sheep intestine, but no significant effect of danofloxacin on transport activity was observed. Evaluation of the interaction of danofloxacin with the breast cancer resistance protein (BCRP) showed that pantoprazole and ivermectin significantly decreased danofloxacin secretion in the rat intestine. Thus, the ivermectin-induced reduction of danofloxacin efflux transport observed in this study may involve BCRP activity but the involvement of P-glycoprotein cannot be ruled out.

The complete mitochondrial DNA sequence of the guanaco (Lama guanicoe): comparative analysis with the vicuña (Vicugna vicugna) genome.

South American camelids comprise the guanaco (Lama guanicoe) and the vicuña (Vicugna vicugna), which are wild species, and the domestic llama (Lama glama) and alpaca (Lama pacos). This paper presents the first complete mitochondrial (mt) genome of the guanaco and the mt coding sequence of the vicuña. The guanaco mtDNA is 16,649 nt long and its composition and organization are similar to the mitochondrial genome of other mammals. Excluding the control region, comparison of the complete guanaco and vicuña mtDNA showed 4.4% sequence divergence. Nucleotide differences in peptide coding genes varied from 1.9% in ATP6 to 6.4% in Cyt b. These values are compatible with the close relatedness of both species identified by other authors. Based on the differences between the control region sequence here reported and that previously described, we also discuss the occurrence of NUMTs in the genome of South American camelids.

Hepatic and extra-hepatic metabolic pathways involved in flubendazole biotransformation in sheep.

Flubendazole (FLBZ) is a broad-spectrum benzimidazole anthelmintic compound used in pigs, poultry and humans. Its potential for parasite control in ruminant species is under investigation. The objective of the work described here was to identify the main enzymatic pathways involved in the hepatic and extra-hepatic biotransformation of FLBZ in sheep. Microsomal and cytosolic fractions obtained from sheep liver and duodenal mucosa metabolised FLBZ into a reduced FLBZ metabolite (red-FLBZ). The keto-reduction of FLBZ led to the prevalent (approximately 98%) stereospecific formation of one enantiomeric form of red-FLBZ. The amounts of red-FLBZ formed in liver subcellular fractions were 3-4-fold higher (P<0.05) compared to those observed in duodenal subcellular fractions. This observation correlates with the higher (P<0.05) carbonyl reductase (CBR) activities measured in the liver compared to the duodenal mucosa. No metabolic conversion was observed following FLBZ or red-FLBZ incubation with sheep ruminal fluid. Sheep liver microsomes failed to convert red-FLBZ into FLBZ. However, this metabolic reaction occurred in liver microsomes prepared from phenobarbital-induced rats, which may indicate a cytochrome P450-mediated oxidation of red-FLBZ. A NADPH-dependent CBR is proposed as the main enzymatic system involved in the keto-reduction of FLBZ in sheep. CBR substrates such as menadione and mebendazole (a non-fluoride analogue of FLBZ), inhibited this liver microsomal enzymatic reaction, which may confirm the involvement of a CBR enzyme in FLBZ metabolism in sheep. This research is a further contribution to the understanding of the metabolic fate of a promissory alternative compound for antiparasitic control in ruminant species.