[An update on amebiasis]. / Amebiasis: aspectos clínicos, terapéuticos y de diagnóstico de la infección.

The description of Entamoeba dispar, and the recovery of Entamoeba moshkovskii from humans had a major impact in the epidemiology and clinical management of amebiasis. Infections range from asymptomatic colonization to hemorrhagic colitis and extra-intestinal diseases. Only a minority of amebiasis patients progress to the development of disease. Recent studies suggest that susceptibility to infection, and its outcome is influenced by the host, parasite genotype, and environment. The identification of Entamoeba histolytica is based on the detection of specific antigens by ELISA and DNA in stool and other clinical samples. Several diagnostic tests have been developed, including polymerase chain reaction, the technique of choice, for the detection and differentiation of E. histolytica, E. dispar, and E. moshkovskii. Combination of serologic tests with detection of the parasite DNA by PCR or antigen by ELISA offers the best approach to diagnosis. However, these techniques are impractical for clinical laboratories of developing countries. Clinicians must follow the guidelines of the World Health Organization to avoid unnecessary treatments. This review describes and discusses recent advances in amebiasis with emphasis in the clinical aspects and management of infection.

[Intestinal parasitic diseases as a global health problem]. / Las enfermedades parasitarias intestinales como un problema de salud global.

In today's world, parasitic disease agents are not restricted by geography or economy, and have become a significant global threat. The increasing globalization of the fresh produce market and greater international trade and travels, have contributed to the spread of these organisms in the industrialized world. Parasitic protozoa cause waterborne and foodborne outbreaks of diarrhea. The unprecedented flow of people introduces cultural and behavior patterns around the world; the increasing tendency to eat raw or undercooked meat and seafood, favors the dissemination of several parasitic pathogens. Climate changes are predicted to cause a global increase in soil-transmitted helminthiases. The multidisciplinary study of these agents, and the interaction among scientists, global health organizations and governments are imperative to reduce the burden of these diseases and improve the life of a large segment of the world population.

Cyclospora cayetanensis Infection in Developed Countries: Potential Endemic Foci?

Cyclospora cayetanensis infection has emerged as a significant public health concern worldwide. Developed countries are generally considered non-endemic for infection. However, sporadic cases and non-travel-related outbreaks of C. cayetanensis infections associated with domestically grown produce are becoming more common in developed countries. Cyclospora cayetanensis has been detected in fresh produce, surface water, wastewater, irrigation water, and soil in these countries, suggesting that the parasite may be more common in areas with advanced sanitation than previously thought and illustrating the potential risk for exposure and indigenous/autochthonous infections. The evidence suggests the possibility of foci of endemicity in developed countries, particularly in communities where sanitary conditions are compromised, and raises transmission issues that require further research to better define the risks for infection, how widespread C. cayetanensis may be in these areas, and to guide interventions against this infection. The main purpose of the present opinion was to evaluate the presence of cyclosporiasis in developed countries, which is a very important and ongoing issue in food safety.

Factors associated with Cyclospora infection in a Venezuelan community: extreme poverty and soil transmission relate to cyclosporiasis.

BACKGROUND: Transmission dynamics of Cyclospora cayetanensis in endemic areas and the factors associated with soil contamination remain unclear. The effects of environmental factors on Cyclospora have been insufficiently studied, particularly in South America, thus a Venezuelan community was studied to profile risk factors for infection. METHODS: A cross-sectional stool survey of 732 individuals was conducted. For Cyclospora screening, an acid-fast-stained smear of formalin-ethyl acetate concentrate and ultraviolet (UV) epifluorescence examination of a wet mount were used. Water (n=14), soil (n=50) and produce (n=77) samples were collected, processed and examined by UV epifluorescence. Data were analysed using multivariate logistic regression. RESULTS: Cyclospora infections were identified in 73 (9.9%) subjects. Variables associated with the infection were age ≤10 y (odds ratio [OR] 14), hut living (OR 5), well water use (OR 18.5), drinking untreated water (OR 7.6), toilet absence (OR 8), having contact with faeces-contaminated soil (OR 4) and poultry exposure (OR 3). Infections (63%) were clustered in 25 huts. Oocysts were identified in 28.6%, 18% and 3.9% of the water, soil and produce samples, respectively. CONCLUSIONS: There was an explicit association of Cyclospora infection with extreme poverty and soil transmission reflecting the household socio-economic correlate of cyclosporiasis in this community.

Cyclospora cayetanensis: A Perspective (2020-2023) with Emphasis on Epidemiology and Detection Methods.

Cyclospora cayetanensis infections are prevalent worldwide, and the parasite has become a major public health and food safety concern. Although important efforts have been dedicated to advance toward preventing and reducing incidences of cyclosporiasis, there are still several knowledge gaps that hamper the implementation of effective measures to prevent the contamination of produce and water with Cyclospora oocysts. Some of these data gaps can be attributed to the fact that access to oocysts is a limiting factor in C. cayetanensis research. There are no animal models or in vivo or in vitro culture systems to propagate the oocysts needed to facilitate C. cayetanensis research. Thus, researchers must rely upon limited supplies of oocysts obtained from naturally infected human patients considerably restricting what can be learnt about this parasite. Despite the limited supply of C. cayetanensis oocysts, several important advances have happened in the past 3 years. Great progress has been made in the Cyclospora field in the areas of molecular characterization of strains and species, generation of genomes, and development of novel detection methods. This comprehensive perspective summarizes research published from 2020 to 2023 and evaluates what we have learnt and identifies those aspects in which further research is needed.

[H-index: a new bibliometric indicator of the academic activity]. / Indice h: nuevo indicador bibliométrico de la actividad académica.

The number of h papers with at least h citations (h-index) has been proposed to evaluate individual scientific research production. This new indicator of academic impact has raised a widespread interest and is growing in popularity. The advantage of this factor is that it combines an assessment of both quantity and quality of the h papers. However, it has limitations and it is not completely suitable to evaluate the research quality of professionals. To avoid these disadvantages, some indicators have been proposed. The authors emphasize the need for combining several indicators in the evaluation process.

[Current pharmacotherapy of amebiasis, advances in new drugs, and design of a vaccine]. / Farmacoterapia actual de la amibiasis, avances en nuevas drogas y diseño de una vacuna.

Although many drugs destroy Entamoeba histolytica within the colonic lumen, the number of tissue amebicides used to treat invasive amebiasis is still relatively limited. Metronidazole (MTZ), which is the drug of choice for invasive amebiasis, and other nitroimidazoles have greatly simplified the chemotherapy of this disease. However, eradication of E. histolytica infection after completion of MTZ therapy requires additional treatment with luminal amebicides, such as paramomycin. After decades of the introduction of MTZ and other nitroimidazoles in the therapy of amebiasis, there have been few innovations in treating amebic infections. Meanwhile, amebiasis remains among the leading causes of morbidity and mortality in the contemporary world. The toxic effects of MTZ and recent failures in the treatment of several intestinal protozoan parasites, has led to a search for other amebicidal drugs. A recent advance is the demonstration of the effect of nitazoxanide, which has broad spectrum of antiparasitic activity, against E. histolytica. This compound could be the key in the therapy of amebiasis by its action against both luminal and invasive parasite forms. However, the design of an effective vaccine against the infection is still being desirable. Work is underway to develop a vaccine and recent experimental studies are promising. The aim of this review is to examine and discuss the most important aspects of current antiamebic pharmacotherapy and the prospects for development of new drugs and a vaccine.

[Microscopic diagnosis of amebiasis: an obsolete method but necessary in the developing world]. / Diagnóstico microscópico de amibiasis: método obsoleto pero necesario en el mundo en desarrollo.

Molecular biology-based diagnosis offers the best approach to detect amebiasis, but remains impractical in the clinical laboratories from the developing world. In these areas, the microscopic diagnosis remains the routine method. It is imperative that a series of fresh stool specimens be examined. The use of a concentration method should become a routine procedure. Permanent stained smears is the most critical and reliable diagnostic method for the microscopic detection of intestinal protozoa. If the direct or concentrate wet mounts were considered as a preliminary examination; and the use of iron-hematoxylin stained smears become a routine procedure, many of the misdiagnosis that frequently occur could be avoided. The iron-hematoxylin stained preparation is the method of choice for the microscopic detection of E. histolytica/E. dispar and other intestinal protozoa.

[Importance of contact with soil in the transmission of cyclosporosis]. / Importancia del contacto con la tierra en la transmisión de la ciclosporosis.

Cyclospora cayetanensis is an emergent pathogen that causes endemic and epidemic diarrhea worldwide. The epidemiology of the infection is not well known. Transmission of the parasite occurs through an environmental vehicle. In industrialized countries, cyclosporosis has been most often associated with either food-borne outbreaks or traveller's diarrhea. In developing countries, infection has been linked with contaminated water or food, contact with animals or soils, and variables related with socioeconomic status. In a Venezuelan community, a strong correlation between environments conducive to fecal contamination and infection was observed, suggesting that direct contact with contaminated soil may be an important route of transmission in areas with substandard housing developments, and poverty a predisposing factor for cyclosporosis.

[Amebiasis: implications of the recognition of Entamoeba dispar and the identification of Entamoeba moshkovskii in humans]. / Amibiasis: implicaciones del reconocimiento de Entamoeba dispar e identificación de Entamoeba moshkovskii en humanos.

The history of Entamoeba histolytica is very confuse and shows several wrong concepts about the parasite and its relationship with the host. The poor correlation between the prevalence of asymptomatic and symptomatic amebiasis originated the proposal of three explicative hypothesis, among them was the concept of Brumpt that E. histolytica comprised two morphologically identical species, E. dysenteriae and E. dispar. The application of modern molecular techniques irrefutably proved that E. histolytica was really a complex of two species, confirming the concept of Brumpt almost 7 decades later. Recent studies have identified in humans E. moshkovskii, morphologically indistinguishable from E. histolytica and E. dispar, a great genetic diversity within each of these species, and heterogeneity in virulence among E. histolytica strains. The redescription of E. dispar, and the recovery of E. moshkovskii from humans have had a major impact in our understanding of E. histolytica and amebiasis with important clinical and epidemiologic implications. This has led to the need of a reevaluation of the infection in terms of prevalence and morbidity in the global population and to study the geographic distribution, prevalence, and transmission pattern of E. histolytica strains in order to detect those with epidemiologic relevance and predict the risk of amebic disease in a population.

Antagonistic effect of luzindole in mice treated with melatonin during the infection with the venezuelan equine encephalomyelitis virus.

The effect of Luzindole (LZ) in mice treated with melatonin (MEL) during the infection with the Venezuelan equine encephalomyelitis (VEE) virus was examined. Melatonin (500 microg/Kg b.w.) was administered daily 3 days before and 5 days after the infection. Luzindole (5 mg/Kg b.w.) was injected intraperitoneally 3 days before (pre-infection) or 5 days after (post-infection) the infection. Mortality rates in the infected mice treated both with MEL and LZ were higher than in those treated with MEL alone in which the lowest brain and serum viral titers were detected. On the third post-infection day, viral titers of the MEL + VEE + LZ (pre-infection) group were higher than those of the remainder groups. On the fifth day, viral titers in infected mice were similar to those of the MEL + VEE + LZ (pre-infection) group, but higher than those detected in the MEL + VEE + LZ (post-infection). In conclusion, the protective effect of MEL in mice infected with VEE virus was inhibited by LZ suggesting that this protection is mediated by MEL receptors.

[Relevance of helminths in the prevention and healing of immune diseases]. / Relevancia de los helmintos en la prevención y curación de las enfermedades inmunes.

The incidence of immune diseases has had a steady significant increase in the industrialized countries since the end of the last century. Epidemiological data suggest that prevention of exposure to helminths may be one of the factors promoting the rise in these diseases. Animal models of immune diseases support this concept by showing that these parasites can prevent and reverse developed diseases. Helminths strongly modulate the host's immune system inducing regulatory immune cells and pathways that afford protection from these illnesses. Helminthic therapy has emerged as a promising treatment for several immune diseases; the potential benefits are startling and new therapeutic strategies for the control of these conditions may result.

Transmission of Cyclospora cayetanensis infection: a review focusing on soil-borne cyclosporiasis.

In industrialised regions, cyclosporiasis has been most often linked with either food-borne outbreaks or foreign travel. In endemic areas, risk factors associated with the infection include contaminated water or food, contact with animals, type of sanitation and contact with soil. In a community from Venezuela, a strong association was observed between environmental contact with faecal-contaminated soil and cyclosporiasis, suggesting that contact with soil may be an important mode of transmission. This paper reviews the transmission of cyclosporiasis, focusing on soil-related infection.

Epidemiology of Cyclospora cayetanensis infection in San Carlos Island, Venezuela: strong association between socio-economic status and infection.

The epidemiology of Cyclospora cayetanensis is not well understood. Few community-based studies have addressed this issue. A study was conducted to determine the prevalence and risk factors for cyclosporiasis in San Carlos Island, Venezuela. A sample of 515 subjects (mean+/-SD: 21.4+/-17.8 years) was surveyed. For identification of the parasite, stools were examined with modified Ziehl-Neelsen carbolfuchsin staining of formalin-ether concentrates. Infections with Cyclospora (43 of 515, 8.3%) were common. There were differences in prevalence of the parasite among sectors of the community: 30 out of 43 (69.8%) cases of cyclosporiasis clustered in two sectors with extreme poverty. Living in these sectors versus the remainder, living in a hut or small residence versus a concrete or larger house, using an area of backyard rather than a toilet or latrine for defecation, and having contact with soil contaminated with human feces were factors strongly associated with the infection (P<0.01). Contact with soil contaminated with human feces might be an important mode of transmission, and poverty a predisposing factor, for the infection.

[Cryptosporidium: phylogeny and taxonomy]. / Cryptosporidium: filogenia y taxonomía.

Members of the genus Cryptosporidium in the phylum Apicomplexa were long thought to be closely related to the coccidia. However, despite strong morphological similarities to these organisms, Cryptosporidium has notable differences with them and similarities with the gregarine protozoa. On the basis of phylogenetic analysis of molecular data, some authors place Cryptosporidium at the basis of the phylum Apicomplexa, others consider species of this genus to be phylogenetically too distant from the coccidia and do not include them in this group of protozoa, and others think that Cryptosporidium is closely related to gregarines. The taxonomy of this genus and the naming of species are undergoing rapid change due to the new and increasing molecular information. Molecular characterization of oocysts using polymerase chain reaction based procedures has not only a major impact on resolving the taxonomy of Cryptosporidium at the species level but also on the molecular epidemiology of cryptosporidiosis. Today, it is recognized that this genus is a phenotypically and genotypically heterogeneous assemblage of largely morphologically identical species and genotypes. Fourteen Cryptosporidium species and 21 C. parvum genotypes are currently recognized. Phylogenetic analyses have shown that genetically related hosts often have related forms of Cryptosporidium. Application of molecular techniques to taxonomy and epidemiology is helping to characterize new and existing species and determine the sources of the parasites that will facilitate the identification of sources of water-borne cryptosporidiosis.

Microsporidiosis in Venezuela: prevalence of intestinal microsporidiosis and its contribution to diarrhea in a group of human immunodeficiency virus-infected patients from Zulia State.

Microsporidia are recognized as a cause of morbidity among patients infected with the human immunodeficiency virus (HIV). Infection rates for intestinal microsporidiosis in HIV-infected patients from Venezuela are unknown. To determine the prevalence and pathogenic role of microsporidia in these patients in northwestern Venezuela, a case control study was conducted in 103 outpatients (mean +/- SD age = 37.3 +/- 5.6 years). Microsporidia were detected using unconcentrated formalin-fixed stools examined by Weber's chromotrope-based staining method. For identification of coccidia, modified Ziehl-Neelsen carbolfuchsin staining of formalin-ether concentrates were used, and for other pathogenic parasites, iron hematoxylin-stained smears and formalin-ether concentrates were examined. Microsporidial infections were detected in 14 (13.6%) of 103 patients and 39 (37.9%) had other parasitic pathogens. No significant difference was noted in the occurrence of the infection in patients with diarrhea (13 of 74, 17.6%) and controls (1 of 29, 3.4%) (P = 0.118). Nevertheless, this result may be due to the small sample size (n = 14) of infected individuals. The proportions of other pathogens in patients with or without diarrhea were not significantly different (P = 0.828). Microsporidiosis is common among the HIV-infected population in northwestern Venezuela. However, its pathogenic role in these patients is uncertain and warrants further investigation.

Prevalence and pathogenic role of Cyclospora cayetanensis in a Venezuelan community.

The prevalence and pathogenic role of Cyclospora cayetanensis among 212 subjects (age range = two months to 70 years) in an impoverished community in Venezuela were assessed retrospectively. For identification of the coccidium, modified Ziehl-Neelsen carbolfuchsin staining of formalin-ether concentrates was used. For other pathogenic parasites, iron-hematoxylin-stained smears and formalin-ether concentrates were examined. Cyclospora infections were identified in 13 (6.1%) subjects with a high percentage of asymptomatic carriers (11 of 13, 84.6%). Only two (15.4%) infants had diarrhea and the coccidium as the single detectable pathogenic parasite. The findings suggest that Cyclospora infections are relatively common and often asymptomatic in this region.