Emerging Parasitic Protozoa

A special issue of Pathogens (ISSN 2076-0817).

Deadline for manuscript submissions: closed (15 November 2019) | Viewed by 37041

Special Issue Editors

Departamento de Obstetricia, Ginecología, Pediatría, Medicina Preventiva y Salud Pública, Toxicología, Medicina Legal y Forense y Parasitología, Universidad de La Laguna (ULL), Avda. Astrofísico F. Sánchez, 2, 38206 La Laguna, Tenerife, Spain
Interests: free living amoebae; therapeutics; emerging parasitic protozoa; diagnosis; natural compounds; synthetic compounds
Special Issues, Collections and Topics in MDPI journals
Departamento de Obstetricia, Ginecología, Pediatría, Medicina Preventiva y Salud Pública, Toxicología, Medicina Legal y Forense y Parasitología, Instituto Universitario de Enfermedades Tropicales y Salud Pública de Canarias, Universidad de La Laguna, Avda. Astrofísico F. Sánchez s/n, 38206 La Laguna, Tenerife, Spain
Interests: Parasite; chemotherapy; Leishmania; Trypanosoma; Free living amoeba; water quality
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

The term emerging and re-emerging infectious diseases have been related to a group of diseases that have appeared in a population in the recent past or that have existed but are rapidly increasing in incidence or changing their geographic range. Among the causative agents, parasitic protozoa are emerging as a global health issue worldwide. This special issue is focused in all aspects of parasitic protozoa diseases from diagnostics to treatment and prevalence and will have a focalized part on Free Living Amoebae.

Free Living Amoebae (FLA) include members that are opportunistic parasitic protozoa and are able to cause infection in humans and other animals. Among these infections, Acanthamoeba keratitis and amoebic encephalitis are among the most reported ones.

Unfortunately, the lack of knowledge on the pathogenesis mechanisms of these protozoa as well as the existence of a highly resistant cyst stage makes the treatment of these amoebae a challenge.

The establishment of standardized diagnostic tools as well as novel fully effective therapeutics agents is among the key issues in this field. Moreover, FLA are gathering importance worldwide as carriers of other pathogenic microorganisms.

This Special Issue is dedicated to FLA and welcomes all researchers working in this field to participate in it.

Dr. Jacob Lorenzo-Morales
Dr. Jose E. Piñero
Guest Editors

Manuscript Submission Information

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Keywords

  • Acanthamoeba
  • Naegleria fowleri
  • Balamuthia mandrillaris
  • Therapy
  • Free living amoebae
  • Amoebae-resisting microorganisms
  • Parasitic Protozoa
  • Leishmania
  • Trypanosoma
  • Cryptosporidium
  • Microsporidia
  • Emerging Diseases

Published Papers (11 papers)

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Editorial

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2 pages, 172 KiB  
Editorial
Emerging Parasitic Protozoa
Pathogens 2020, 9(9), 704; https://doi.org/10.3390/pathogens9090704 - 27 Aug 2020
Viewed by 3137
Abstract
The terms emerging and re-emerging infectious diseases have been related to a group of diseases that have appeared in a population in the recent past or that have existed but are rapidly increasing in incidence or changing their geographic range [...] Full article
(This article belongs to the Special Issue Emerging Parasitic Protozoa)

Research

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13 pages, 2789 KiB  
Article
Isolation of Naegleria spp. from a Brazilian Water Source
Pathogens 2020, 9(2), 90; https://doi.org/10.3390/pathogens9020090 - 31 Jan 2020
Cited by 20 | Viewed by 4323
Abstract
The genus Naegleria, of the free-living amoeba (FLA) group, has been investigated mainly due to its human health impact, resulting in deadly infections and their worldwide distribution on freshwater systems. Naegleria fowleri, colloquially known as the “brain-eating amoeba,” is the most [...] Read more.
The genus Naegleria, of the free-living amoeba (FLA) group, has been investigated mainly due to its human health impact, resulting in deadly infections and their worldwide distribution on freshwater systems. Naegleria fowleri, colloquially known as the “brain-eating amoeba,” is the most studied Naegleria species because it causes primary amoebic meningoencephalitis (PAM) of high lethality. The assessment of FLA biodiversity is fundamental to evaluate the presence of pathogenic species and the possibility of human contamination. However, the knowledge of FLA distribution in Brazil is unknown, and to rectify this situation, we present research on identifying Naegleria spp. in the Monjolinho River as a model study. The river is a public Brazilian freshwater source that crosses the city of São Carlos, in São Paulo state, Brazil. Five distinct sampling sites were examined through limnological features, trophozoites culturing, and PCR against internal transcribed spacer (ITS) regions and 5.8S rRNA sequences. The results identified N. philippinensis, N. canariensisi, N. australiensis, N. gruberi, N. dobsoni sequences, as well as a Hartmannella sequence. The methodology delineated here represents the first Brazilian Naegleria spp. study on a freshwater system. Our results stress the urgency of a large scale evaluation of the presence of free-living amoebas in Brazil. Full article
(This article belongs to the Special Issue Emerging Parasitic Protozoa)
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14 pages, 6229 KiB  
Article
Effects of Shape and Size of Cobalt Phosphate Nanoparticles against Acanthamoeba castellanii
Pathogens 2019, 8(4), 260; https://doi.org/10.3390/pathogens8040260 - 22 Nov 2019
Cited by 20 | Viewed by 3207
Abstract
T4 genotype Acanthamoeba are opportunistic pathogens that cause two types of infections, including vision-threatening Acanthamoeba keratitis (AK) and a fatal brain infection known as granulomatous amoebic encephalitis (GAE). Due to the existence of ineffective treatments against Acanthamoeba, it has become a potential [...] Read more.
T4 genotype Acanthamoeba are opportunistic pathogens that cause two types of infections, including vision-threatening Acanthamoeba keratitis (AK) and a fatal brain infection known as granulomatous amoebic encephalitis (GAE). Due to the existence of ineffective treatments against Acanthamoeba, it has become a potential threat to all contact lens users and immunocompromised patients. Metal nanoparticles have been proven to have various antimicrobial properties against bacteria, fungi, and parasites. Previously, different types of cobalt nanoparticles showed some promise as anti-acanthamoebic agents. In this study, the objectives were to synthesize and characterize the size, morphology, and crystalline structure of cobalt phosphate nanoparticles, as well as to determine the effects of different sizes of cobalt metal-based nanoparticles against A. castellanii. Cobalt phosphate octahydrate (CHP), Co3(PO4)2•8H2O, was synthesized by ultrasonication using a horn sonicator, then three different sizes of cobalt phosphates Co3(PO4)2 were produced through calcination of Co3(PO4)2•8H2O at 200 °C, 400 °C and 600 °C (CP2, CP4, CP6). These three types of cobalt phosphate nanoparticles were characterized using a field emission scanning electron microscope (FESEM), energy dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD) analysis. Next, the synthesized nanoparticles were subjected to biological assays to investigate their amoebicidal, amoebistatic, anti-encystation, and anti-excystation effects against A. castellanii, as well as cell cytotoxicity. The overall results showed that 1.30 ± 0.70 µm of CHP microflakes demonstrated the best anti-acanthemoebic effects at 100 µg/mL, followed by 612.50 ± 165.94 nm large CP6 nanograins. However, amongst the three tested cobalt phosphates, Co3(PO4)2, the smaller nanoparticles had stronger antiamoebic effects against A. castellanii. During cell cytotoxicity analysis, CHP exhibited only 15% cytotoxicity against HeLa cells, whereas CP6 caused 46% (the highest) cell cytotoxicity at the highest concentration, respectively. Moreover, the composition and morphology of nanoparticles is suggested to be important in determining their anti-acathamoebic effects. However, the molecular mechanisms of cobalt phosphate nanoparticles are still unidentified. Nevertheless, the results suggested that cobalt phosphate nanoparticles hold potential for development of nanodrugs against Acanthamoeba. Full article
(This article belongs to the Special Issue Emerging Parasitic Protozoa)
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11 pages, 1155 KiB  
Article
Antioxidant and Leishmanicidal Evaluation of Pulicaria Inuloides Root Extracts: A Bioguided Fractionation
Pathogens 2019, 8(4), 201; https://doi.org/10.3390/pathogens8040201 - 23 Oct 2019
Cited by 8 | Viewed by 2563
Abstract
Leishmaniasis remains a major world health problem, and in particular, Algeria ranks second for the incidence of cutaneous leishmaniasis. Pulicaria inuloides is a well-known Arabian Peninsula medicinal plant. In the present study, the chloroform, ethyl acetate and n-butanol extracts from the roots [...] Read more.
Leishmaniasis remains a major world health problem, and in particular, Algeria ranks second for the incidence of cutaneous leishmaniasis. Pulicaria inuloides is a well-known Arabian Peninsula medicinal plant. In the present study, the chloroform, ethyl acetate and n-butanol extracts from the roots of Pulicaria inuloides were analyzed for antioxidant activity and its correlation with the total phenolic and flavonoid contents. The highest antioxidant activity using a DPPH assay was showed by the ethyl acetate extract (IC50 4.08 µg/mL), which also had the highest total phenolic content (307.12 µgAGE). Furthermore, P. inuloides root extracts were evaluated against Leishmania amazonensis and Leishmania donovani. The results highlighted the chloroform extract as the most active one against both tested Leishmania strains. A bioguided fractionation of the chloroform extract led to the isolation of (8R:8S)-(75:25 er)-10-isobutyryloxy-8,9-epoxy-thymol isobutyrate as the main bioactive component, showing a potent leishmanicidal activity on L. amazonensis promatigote and amastigote stages (IC50 5.03 and 2.87 µM, respectively) and a good selectivity index on murine macrophages (CC50 19.37 µM). This study provides the first report of the antioxidant and leishmanicidal activities of P. inuloides root extracts and the results point to this species as a source of potential bioactive agents. Full article
(This article belongs to the Special Issue Emerging Parasitic Protozoa)
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13 pages, 2267 KiB  
Article
Withanolides from Withania aristata as Antikinetoplastid Agents through Induction of Programmed Cell Death
Pathogens 2019, 8(4), 172; https://doi.org/10.3390/pathogens8040172 - 01 Oct 2019
Cited by 14 | Viewed by 2479
Abstract
Leishmaniasis and American trypanosomiasis are parasitic diseases that cause significant clinical, social and economic impact on the population of tropical and subtropical countries. Their current treatment is limited and presents multiple drawbacks, including high toxicity, high cost, lengthy treatment plans, as well as [...] Read more.
Leishmaniasis and American trypanosomiasis are parasitic diseases that cause significant clinical, social and economic impact on the population of tropical and subtropical countries. Their current treatment is limited and presents multiple drawbacks, including high toxicity, high cost, lengthy treatment plans, as well as the emergence of resistant species. Therefore, there is a need to find new lead compounds with high potency against parasites and low toxicity in patients. In the present work, the bioguided fractionation of an endemic plant from the Canary Islands, Withania aristata, led to the identification of withanolide-type metabolites (13) with leishmanicidal and trypanocidal activities. Compounds 1 and 3 showed a significant dose-dependent inhibition effect on the proliferation of L. amazonensis promastigotes and T. cruzi epimastigotes, higher than the reference drugs, miltefosine and benznidazole, respectively. Moreover, compounds 13 were more potent (IC50 0.055–0.663 µM) than the reference drug against the intracellular amastigote stage of L. amazonensis, with a high selectivity index on murine macrophage cells (SI 58.66–216.73). Studies on the mechanism of death showed that the compounds induced programmed cell death or that which was apoptosis-like. The present findings underline the potential of withanolides as novel therapeutic antikinetoplastid agents. Full article
(This article belongs to the Special Issue Emerging Parasitic Protozoa)
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13 pages, 1286 KiB  
Article
Predictors of Failure from Primary Therapy for Giardiasis in San Diego: A Single Institution Retrospective Review
Pathogens 2019, 8(4), 165; https://doi.org/10.3390/pathogens8040165 - 27 Sep 2019
Cited by 3 | Viewed by 2287
Abstract
This study aimed to determine the presence of giardiasis among HIV patients in San Diego, the rate of failure of metronidazole treatment, and factors associated with treatment failure. We used a 7 year retrospective single-center case series of HIV-infected individuals with giardiasis at [...] Read more.
This study aimed to determine the presence of giardiasis among HIV patients in San Diego, the rate of failure of metronidazole treatment, and factors associated with treatment failure. We used a 7 year retrospective single-center case series of HIV-infected individuals with giardiasis at University of California San Diego Medical Center. Data were analyzed for the changes in the hematological, biochemical, and immunologic results at pre- and at-diagnosis levels. We also compared the changes at the diagnosis level among patients who were treated successfully and those who experienced treatment failure as defined by retreatment with a second course of antibiotics. In 29 Giardia lamblia-infected HIV patients, following diagnosis of G. lamblia, there was a non-significant decrement in cluster of differentiation 4 (CD4), but a statistically significant increase in the number of white blood cell (WBC). Other indices did not differ between pre- and at-diagnosis levels. Twenty patients (69%) were treated with a single course of metronidazole or tinidazole and seven patients (24.1%) were treated with more than one course of metronidazole. These seven patients had statistically significant higher hemoglobin at the time of diagnosis, but further studies are required to confirm if this is a consistent finding and if this can predict failure from primary therapy. Full article
(This article belongs to the Special Issue Emerging Parasitic Protozoa)
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14 pages, 3802 KiB  
Article
Ursolic Acid Derivatives as Potential Agents Against Acanthamoeba Spp.
Pathogens 2019, 8(3), 130; https://doi.org/10.3390/pathogens8030130 - 23 Aug 2019
Cited by 17 | Viewed by 3613
Abstract
The current chemotherapy of Acanthamoeba keratitis relies on few drugs with low potential and limited efficacy, for all this there is an urgent need to identify new classes of anti-Acanthamoeba agents. In this regard, natural products play an important role in overcoming [...] Read more.
The current chemotherapy of Acanthamoeba keratitis relies on few drugs with low potential and limited efficacy, for all this there is an urgent need to identify new classes of anti-Acanthamoeba agents. In this regard, natural products play an important role in overcoming the current need and medicinal chemistry of natural products represents an attractive approach for the discovery and development of new agents. Ursolic acid, a natural pentacyclic triterpenoid compound, possesses a broad spectrum of activities including anti-Acanthamoeba. Herein, we report on the development by chemical transformation of an ursolic acid-based series of seven compounds (2–8), one of them reported for the first time. The structure-activity relationship (SAR) analysis of their anti-Acanthamoeba activity revealed that acylation/ether formation or oxidation enhances their biological profile, suggesting that the hydrophobic moiety contributes to activity, presumably by increasing the affinity and/or cell membrane permeability. These ursolic acid derivatives highlight the potential of this source as a good base for the development of novel therapeutic agents against Acanthamoeba infections. Full article
(This article belongs to the Special Issue Emerging Parasitic Protozoa)
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12 pages, 3535 KiB  
Article
Curcumin Attenuates the Pathogenicity of Entamoeba histolytica by Regulating the Expression of Virulence Factors in an Ex-Vivo Model Infection
Pathogens 2019, 8(3), 127; https://doi.org/10.3390/pathogens8030127 - 15 Aug 2019
Cited by 6 | Viewed by 4388
Abstract
Infection with the enteric protozoan Entamoeba histolytica is still a serious public health problem, especially in developing countries. Amoebic liver abscess (ALA) is the most common extraintestinal manifestation of the amoebiasis, and it can lead to serious and potentially life-threatening complications in some [...] Read more.
Infection with the enteric protozoan Entamoeba histolytica is still a serious public health problem, especially in developing countries. Amoebic liver abscess (ALA) is the most common extraintestinal manifestation of the amoebiasis, and it can lead to serious and potentially life-threatening complications in some people. ALA can be cured by metronidazole (MTZ); however, because it has poor activity against luminal trophozoites, 40–60% of treated patients get repeated episodes of invasive disease and require repeated treatments that can induce resistance to MTZ, this may emerge as an important public health problem. Anti-virulence strategies that impair the virulence of pathogens are one of the novel approaches to solving the problem. In this study, we found that low doses of curcumin (10 and 50 μM) attenuate the virulence of E. histolytica without affecting trophozoites growth or triggering liver injury. Curcumin (CUR) decreases the expression of genes associated with E. histolytica virulence (gal/galnac lectin, ehcp1, ehcp5, and amoebapore), and is correlated with significantly lower amoebic invasion. In addition, oxidative stress is critically involved in the etiopathology of amoebic liver abscess; our results show no changes in mRNA expression levels of superoxide dismutase (SOD) and catalase (CAT) after E. histolytica infection, with or without CUR. This study provides clear evidence that curcumin could be an anti-virulence agent against E. histolytica, and makes it an attractive potential starting point for effective treatments that reduce downstream amoebic liver abscess. Full article
(This article belongs to the Special Issue Emerging Parasitic Protozoa)
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11 pages, 6927 KiB  
Article
In Vitro Activity of Statins against Naegleria fowleri
Pathogens 2019, 8(3), 122; https://doi.org/10.3390/pathogens8030122 - 08 Aug 2019
Cited by 22 | Viewed by 4667
Abstract
Naegleria fowleri causes a deadly disease called primary amoebic meningoencephalitis (PAM). Even though PAM is still considered a rare disease, the number of reported cases worldwide has been increasing each year. Among the factors to be considered for this, awareness about this disease, [...] Read more.
Naegleria fowleri causes a deadly disease called primary amoebic meningoencephalitis (PAM). Even though PAM is still considered a rare disease, the number of reported cases worldwide has been increasing each year. Among the factors to be considered for this, awareness about this disease, and also global warming, as these amoebae thrive in warm water bodies, seem to be the key factors. Until present, no fully effective drugs have been developed to treat PAM, and the current options are amphotericin B and miltefosine, which present side effects such as liver and kidney toxicity. Statins are able to inhibit the 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase, which is a key enzyme for the synthesis of ergosterol of the cell membrane of these amoebae. Therefore, the in vitro activity of a group of statins was tested in this study against two types of strains of Naegleria fowleri. The obtained results showed that fluvastatin was the most effective statin tested in this study and was able to eliminate these amoebae at concentrations of 0.179 ± 0.078 to 1.682 ± 0.775 µM depending on the tested strain of N. fowleri. Therefore, fluvastatin could be a potential novel therapeutic agent against this emerging pathogen. Full article
(This article belongs to the Special Issue Emerging Parasitic Protozoa)
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10 pages, 1666 KiB  
Article
In Vitro Evaluation of Combined Commercialized Ophthalmic Solutions Against Acanthamoeba Strains
Pathogens 2019, 8(3), 109; https://doi.org/10.3390/pathogens8030109 - 25 Jul 2019
Cited by 3 | Viewed by 2346
Abstract
Acanthamoeba is a free-living amoebae genus which is present worldwide in natural and artificial environments. These amoebae are clinically important as causative agents of diseases in humans and other animals such as a fatal encephalitis or a sight threatening Acanthamoeba keratitis (AK). Lately; [...] Read more.
Acanthamoeba is a free-living amoebae genus which is present worldwide in natural and artificial environments. These amoebae are clinically important as causative agents of diseases in humans and other animals such as a fatal encephalitis or a sight threatening Acanthamoeba keratitis (AK). Lately; studies have focused on the search of novel therapeutic options for AK but also to prevent infections. Furthermore; the evaluation of commercialized products seems to be an option for this case since not clinical assays would be required. Thus; we aimed to test the amoebicidal activity of different mixtures of two commercial ophthalmic solutions: Systane® Ultra; which has already shown anti-Acanthamoeba properties; and Naviblef® Daily Care. In addition, we tested their cytotoxic effect against murine macrophages. At the individual level; Naviblef® Daily Care showed to be the most active product against Acanthamoeba spp. Nevertheless; the combinations of Systane® Ultra and Naviblef® Daily Care; showed an improvement in the activity against trophozoites and cysts of Acanthamoeba castellanii Neff. Moreover; the concentration necessary to generate cytotoxic effect against murine macrophages (J774.1) was much higher than the required for the amoebicidal and cysticidal effect achieved in the most effective mixtures. Full article
(This article belongs to the Special Issue Emerging Parasitic Protozoa)
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Other

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7 pages, 231 KiB  
Brief Report
Serological and Molecular Findings of Leishmania Infection in Healthy Donkeys (Equus asinus) from a Canine Leishmaniosis Endemic Focus in Tuscany, Italy: A Preliminary Report
Pathogens 2019, 8(3), 99; https://doi.org/10.3390/pathogens8030099 - 09 Jul 2019
Cited by 8 | Viewed by 2522
Abstract
Leishmania parasites are considered to be emergent zoonotic pathogens, which is a new concept regarding their epidemiology and the identification of novel animal hosts. The present study is the first in Italy to evaluate anti Leishmania seroprevalence, and the first in Europe to [...] Read more.
Leishmania parasites are considered to be emergent zoonotic pathogens, which is a new concept regarding their epidemiology and the identification of novel animal hosts. The present study is the first in Italy to evaluate anti Leishmania seroprevalence, and the first in Europe to detect parasite DNA in donkeys’ blood. The study was performed on jennies living in a Leishmania infantum endemic area of Central Italy. One hundred and ten blood samples were obtained from 67 healthy lactating Amiatina jennies that were semi-extensively reared in Tuscany. When possible, more than one sample was subsequently obtained from the same subject. All samples were processed by immunofluorescence antibody test (IFAT) and by polymerase chain reaction (PCR). For the results, 11 out of 30 animals (36.7%) showed positive scores under IFAT. In addition, 22 out of the other 37 jennies had positive scores, also. The animals showed titers ranging from 40 to 320. Furthermore, 2 subjects that were submitted for 2 and 3 blood samplings, both had more than one positive score. Moreover, 2 seropositive animals were positive for Leishmania DNA. Donkeys are considered to be a preferred source for a sandfly blood meal, even if clinical leishmaniosis has never been reported in Europe for this animal species. In the view of these facts, our preliminary findings would suggest the role of donkey as a potential reservoir for this protozoan agent. Additional studies would be welcome to elucidate the role of the donkey in Leishmania epidemiology of CanL endemic areas and to confirm the preliminary findings and the hypothesis proposed here. Full article
(This article belongs to the Special Issue Emerging Parasitic Protozoa)
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