An emerging pattern of public doubt in scientific and political authorities has been seen during the COVID-19 pandemic, where numerous alternatives to vaccinations have gone viral. Ivermectin's growth from a relatively known specialist drug to a political controversy is a striking example of the amplification that social media can provide. Doubt in the dangers of illness has occurred in regard to previous diseases with limited impact, including the Zika virus, Ebola, and H1N1. However, the COVID-19 pandemic's impact in the United States is a much larger example of the gaps in current risk assessments and methods of public health authorities. Publicly available Twitter data was mined to identify tweets discussing ivermectin and vaccination during the first year of COVID-19, before public discussion of ivermectin took off. Those tweets were coded using textual analysis and examined through the use of statistical tools. I examine existing sociological studies about trust in medical authority, vaccine rejection, diffusion of new information, and risk analysis to provide context for my results. Attitudes towards vaccination influenced attitudes towards ivermectin inversely. Negative attitudes towards COVID-19 vaccination were associated with more positive attitudes towards ivermectin. Mentions of pharmaceuticals, deaths during the vaccine wait, or a vaccine conspiracy were additionally significant, all of which led to more positive attitudes towards ivermectin.

Charles University Faculty of Pharmacy in Hradec Králové Department of Pharmacology and Toxicology Student: Dominika Sobotová Tutor: PharmDr. Ivan Vokřál, Ph.D. Title of diploma thesis: Pharmacokinetics of ivermectin in the sheep feces Key words: ivermectin, pharmacokinetics, sheep, anthelminthic Infection with internal parasites (endoparasites) is one of the most common diseases in sheep. Infection with these parasites mainly with the barber's pole worm (Haemonchus contortus) causes considerable economic losses and has a significant impact on sheep productivity. Anthelmintics, including ivermectin, are used for treatment. Ivermectin belongs to the class of macrocyclic lactones and is characterised by broad spectrum and low toxicity. On the other hand, it poses a risk to the environment in form of residues that are excreted in feces by treated individuals. The aim of this study was to determine the excretion profile of ivermectin in sheep subcutaneously administered in a standard dose 0,2 mg/kg of body weight. UHPLC/MS/MS method was used for the analysis of ivermectin fecal concentration. Based on the obtained results we determined basic pharmacokinetic parameters which includes time to achieve maximum concentration (tmax), maximum concentration (cmax), area under the curve (AUC) and mean residence...

The avermectins (ivermectin, doramectin etc) and milbemycins are effective anthelmintics used widely in animal and human medicine for the past twenty years. The actual site of action of the avermectins on the GluCl is unclear, but binding studies have concluded that it does not share a binding site with glutamate. The GluCl channels have been well characterised in Caenorhabditis elegans and are beginning to be characterised in parasitic nematode species such as Haemonchus contortus, Dirofilaria immitis and Cooperia oncophora. The aim of this project was to characterise the H. contortus GluClα3B subunit and its interactions with agonists, glutamate and ivermectin using electrophysiology to study Xenopus oocytes expressing GluClα3B homomeric channels and ligand binding studies on COS-7 cells expressing the subunits. Site–directed mutagenesis was used to introduce resistance associated candidate polymorphisms into the H. contortus GluClα3B subunit. The effects of these changes on the response to glutamate and ivermectin were assessed. One mutation found in IVR C. oncophora, L256F, confers a 3-fold loss of sensitivity to glutamate and a 6.5 fold loss of sensitivity to IVM. This mutation is found in the C-terminal area of the extracellular region of the channel and, from homology modelling, we know it lies in close proximity and possibly interferes with another candidate mutation V235A, and the Cysteine residue at position 192 which forms one side of the structurally significant disulphide bridge. Further introduction of different mutations at this position showed the larger the substituted amino acid, the greater the effect on IVM sensitivity. Another amino acid substitution (T300S) results in the prohibition of a functional channel. The protein is produced and is able to bind IVM with high affinity but does not create a functional channel. These data show that polymorphisms found in field isolates of parasites can have a significant effect on GluCl channels and may contribute to drug resistance.

The purpose of this project is to analyze and study the absorption of the substances ivermectin, spinosad and barettin to hydrophobic and hydrophilic surfaces, and to analyze and study if the barnacle larva are effected when they try to settle on the treated surface. Incubation tests with barnacle larva in Petri dishes were performed as well as absorption tests on hydrophobic and hydrophilic surfaces which were tested with ellipsometry. To determine the surface thickness. The barnacles were placed in hydrophobic as well as hydrophilic Petri dishes that had been incubated with ivermectin, spinosad or barettin. After four to six days the larva was counted to analyze the settling. From the results conclusions could be drawn about the adsorption abilities of the substances to the different surfaces. The barnacles were placed in hydrophobic as well as hydrophilic Petri dishes that had been incubated with ivermectin, spinosad or barettin. After four to six days the larva was counted to analyze the settling. From the results conclusions could be drawn about the adsorption abilities of the substances to the different surfaces. To analyze the adsorption abilities, pieces of silicon oxide were prepared with hydrophobic and hydrophilic poly dimethyl siloxan groups, and albumine. The pieces were then analyzed with ellipsometry. The larva's mortality was very high in the first tests. It can be explained with them being stored too cold the first days, which might have caused their death. It might also be because of contamination from the net used to move the larva, since it was in contact with all the substances concentrations. The standard deviations from the ellipsometry tests are very high, most likely due to uneven adsorption of the substances to the surface. With more tests and measurements, more accurate results could have been sustained The purpose of this project is to analyze and study the absorption of the substances ivermectin, spinosad and barettin to hydrophobic and hydrophilic surfaces, and to analyze and study if the barnacle larva are effected when they try to settle on the treated surface. Incubation tests with barnacle larva in Petri dishes were performed as well as absorption tests on hydrophobic and hydrophilic surfaces which were tested with ellipsometry. To determine the surface thickness. The barnacles were placed in hydrophobic as well as hydrophilic Petri dishes that had been incubated with ivermectin, spinosad or barettin. After four to six days the larva was counted to analyze the settling. From the results conclusions could be drawn about the adsorption abilities of the substances to the different surfaces. The barnacles were placed in hydrophobic as well as hydrophilic Petri dishes that had been incubated with ivermectin, spinosad or barettin. After four to six days the larva was counted to analyze the settling. From the results conclusions could be drawn about the adsorption abilities of the substances to the different surfaces. To analyze the adsorption abilities, pieces of silicon oxide were prepared with hydrophobic and hydrophilic poly dimethyl siloxan groups, and albumine. The pieces were then analyzed with ellipsometry. The larva's mortality was very high in the first tests. It can be explained with them being stored too cold the first days, which might have caused their death. It might also be because of contamination from the net used to move the larva, since it was in contact with all the substances concentrations. The standard deviations from the ellipsometry tests are very high, most likely due to uneven adsorption of the substances to the surface. With more tests and measurements, more accurate results could have been sustained

Resistance to ivermectin (IVM) in Haemonchus contortus has developed in many countries and its mechanism is still under investigation. P-glycoproteins (P-gp) are transmembrane proteins that can transport drugs out of cells. Researchers have found that there is polymorphism in a P-gp gene from H. contortus between IVM-selected and unselected worms. Three main P-gp polymorphs were identified, polymorph A was found to be related to IVM selection, while polymorphs B and X were associated with susceptibility. The purpose of this research is to investigate the genetic variations in P-glycoprotein that are associated with IVM selection or susceptibility in H. contortus. Total RNA and genomic DNA were extracted from individual male adult worms of IVM-selected and unselected strains of H. contortus. A fragment of the P-gp gene was amplified from the genomic DNA of individual worms and RFLP analysis was performed on the PCR product to genotype the corresponding worms. The homozygous worms that possessed polymorph A, B or X were identified.

Glutamate-gated chloride channels (GluCls) are the proposed site of action for macrocyclic lactone anthelminthics, such as IVM, and the milbemycins, such as MOX. The objective of this thesis was to determine whether Haemonchus contortus GluCls are important targets for these anthelminthics. To begin to address this we cloned a full length GluCl alpha-subunit cDNA from H. contortus (HcGluCla). This subunit shares a high homology with GluCl subunits from Caenhorhabditis elegans that have been shown to be important targets for IVM, suggesting that HcGluCla is also an IVM target. However, if HcGluCla is an IVM receptor then it should contain an IVM binding site. To investigate this, the HcGluCla gene was expressed in COS-7 cells. The resulting subunit bound [3H]IVM and [ 3H]MOX with affinities sufficiently high enough to explain their high in vivo potency. Interestingly, glutamate was an allosteric modulator of [ 3H]MOX and [3H]IVM binding where it increased the affinity of these drugs to HcGluCla. To gain further insight into the potentiation of IVM, various glutamatergic and non-glutamatergic ligands were screened for their ability to enhance [3H]IVM binding to HcGluCla. Of the ligands tested, only the GluCl agonists glutamate and ibotenate potentiated [3H]IVM binding. It is possible therefore that if IVM interacts with GluCls in vivo then IVM efficacy may be enhanced by GluCl agonists. To examine this, we tested whether ibotenate could enhance IVM efficacy in gerbils infected with H. contortus. In in vivo efficacy studies, ibotenate (at 1 mg/kg) increased IVM efficacy by 15% (p = 0.048). The enhancement of IVM efficacy in vivo by a GluCl agonist suggests that one of the IVM targets in H. contortus is the GluCl. Finally, to determine the potential physiological response from an interaction between IVM and H. contortus GluCls, we expressed HcGluCla in Xenopus oocytes. HcGluCla expressed in oocytes formed a homomeric channel that responded to

Glutamate binding studies on membrane preparations from unselected and ivermectin-selected strains of the parasitic nematode of ruminants, Haemonchus contortus, indicated a single class of saturable, high affinity binding sites which are sensitive to ivermectin and exhibit different pharmacological characteristics from any known mammalian glutamate receptor. These studies showed that H. contortus larvae possess substantially more glutamate binding sites with lower affinity than adults. Moreover, selection with ivermectin was associated with an increase in the number of glutamate binding sites in adults and an increase in the affinity for glutamate binding in larvae. When investigating the effects of ivermectin on glutamate binding kinetics, it was discovered that ivermectin decreased Bmax values in unselected, but not in ivermectin-selected, parasites. Inulin intake studies were performed in unselected and ivermectin-selected H. contortus worms to relate the glutamate binding results to the biological activity, pharyngeal pumping. These studies showed that glutamate, ivermectin and the structurally similar anthelmintic, moxidectin, inhibit pharyngeal pumping, and that glutamate influences the effects of ivermectin and of moxidectin, on pharyngeal pumping. Lastly, selection with ivermectin was associated with an alteration of the effects of ivermectin, but not moxidectin, on pharyngeal pumping. The results of this work suggest that a novel ivermectin-sensitive, glutamate receptor, which influences pharyngeal function, is involved in the development of ivermectin resistance in H. contortus.

No description available.

Ivermectin also called the wonder drug has been used over the years to control internal and external parasites in livestock. In humans it has been used for the control of several neglected tropical diseases. With regards to efforts to control malaria, mass drug administration (MDA) of ivermectin in humans and livestock has been considered as a potential tool. This is due to challenges in malaria preventive strategies such as insecticide resistance in mosquitoes, shift in their behaviors and residual transmission. Ivermectin reduces malaria transmission by targeting the mosquito nervous system resulting in their death. Ivermectin and its metabolites could have great impacts on the environment as well as human and health. In temperate settings, impacts of ivermectin in the environment were studied due to intense use of the drug in livestock. There is also a necessity to study effects of ivermectin in the tropics before MDA for malaria vector control. Despite its great potential, previous studies done recorded toxicity and sensitivity of the drug to most arthropods mainly dung organisms because ivermectin is released in dung at high concentrations for the case of livestock. With dung organism activity being affected the dung decomposition process is disrupted, cattle avoid these grazing areas leading to financial losses. In the tropics where there is a high number of malaria cases, there is no information on the impacts of the drug in the environment. We placed standardized dung pats from ivermectin-treated and control cattle to determine the effect of ivermectin on dung degradation and dung fauna in Tanzania. For the dung degradation study, at 15, 30 and 45 days post placement, we observed a total of 220 dung pats in the field. We measured termite colonization; wet weight of the entire pat; water content; dry weight of the 10 g subsamples and organic matter from subsamples and the whole pat. For the dung fauna study, we collected fresh dung 3, 10 and 29 days post treatment and put the pats out in the field to be colonized by insects before being transferred to emergence traps. We also did a semi field study where we collected dung pats 1,2,3 and 5 days post treatment to obtain larvae counts. We qualitatively assessed insect larvae activity in the field experiment and observed and counted larvae in the semi field study. We found that termites colonized pats from cattle treated with ivermectin more readily compared to controls (p < 0.001). Compared to control pats, the treated pats' wet weight decreased more slowly on day 15 (p < 0.001), day 30 (p < 0.001), and on day 45 (p = 0.037). Percent dry weight increased over time and similarly between the treatments as water content decreased. Organic matter of the 10g sub samples was similar between the treatments. Total organic matter in the whole pats showed significant differences on day 15 (p < 0.001), and day 30 (p = 0.003), but not on day 45 (p = 0.291). Qualitatively, we observed that pats from treated cattle had less insect larvae activity as compared to controls in the field study. In the semi field study, we counted less larvae in the pats from ivermectin-treated cattle than in the control pats (p < 0.001). Our results indicate that ivermectin and its residues affect dung degradation and dung fauna in tropical savanna settings, and the environmental safety may be at risk upon mass drug administration in livestock. / Master of Science in Life Sciences / Ivermectin is a drug commonly used in livestock and humans to control most parasitic infections. Malaria is a disease transmitted by female Anopheles mosquitoes and prevalent in tropical regions mostly the sub-Saharan Africa. There are efforts worldwide to reduce transmission of malaria such as the used of insecticide treated bed nets as well as use of repellents and spraying insecticides indoors. These efforts are challenged by insecticide resistance in mosquitoes, change in mosquito behavior as well as remaining malaria cases after such interventions are applied. With such challenges comes a need to use ivermectin which has the ability to kill mosquitoes. Despite its great potential, evidence from temperate regions record that ivermectin affects the environment by decreasing dung insect activity, affecting the developmental process and causing a delay in dung decomposition. These effects cause cattle to avoid such pasture areas, resulting in an increase in pest pressure and affecting the economy in general. In the tropics where malaria is prevalent and plans are in place to use ivermectin in mass drug administration for mosquito control, there is a need to look at the environmental impact of the drug. We placed 1 kg dung pats from ivermectin-treated and control cattle to determine the effect of ivermectin on dung degradation and dung fauna in Tanzania. For the dung degradation study; at 15, 30 and 45 days after pats were placed in the field, we observed a total of 220 dung pats. We measured termite colonization; wet weight of the entire pat; water content; dry weight of the 10 g subsamples and organic matter from subsamples and the whole pat. For the dung fauna study, we collected fresh dung 3,10 and 29 days post treatment and put the pats out in the field to be colonized by insects before being transferred to emergence traps. We also did a semi field study where pats were collected 1,2,3 and 5 days post treatment to obtain larvae counts. We qualitatively assessed insect larvae activity in the field experiment and observed and counted larvae in the semi field study. We found that termites colonized pats from cattle treated with ivermectin more readily compared to controls, and treated pats' wet weight decreased more slowly. Dry weight of dung increased as water content decreased with no differences between the treatments. Organic matter of the subsamples did not differ in the treatments but the average mass of organic matter of the individual dung pats decreased slower in ivermectin-treated pats. Qualitatively, we observed that pats from treated cattle had less insect larvae activity as compared to controls in the field study. In the semi field study, we counted more larvae in control pats than the ivermectin pats. Our results indicate that ivermectin and its residues affect dung degradation and dung fauna in tropical savanna settings, and the environmental safety may be at risk upon mass drug administration setting.

No description available.