https://apha.confex.com/apha/responses/129am/165.pdf

Effects of environmental change on emerging parasitic diseases.

Summary: Blastocystis is an unusual enteric protozoan parasite of humans and many animals. It has a worldwide distribution and is often the most commonly isolated organism in parasitological surveys. The parasite has been described since the early 1900s, but only in the last decade or so have there been significant advances in our understanding of Blastocystis biology. However, the pleomorphic nature of the parasite and the lack of standardization in techniques have led to confusion and, in some cases, misinterpretation of data. This has hindered laboratory diagnosis and efforts to understand its mode of reproduction, life cycle, prevalence, and pathogenesis. Accumulating epidemiological, in vivo, and in vitro data strongly suggest that Blastocystis is a pathogen. Many genotypes exist in nature, and recent observations indicate that humans are, in reality, hosts to numerous zoonotic genotypes. Such genetic diversity has led to a suggestion that previously conflicting observations on the pathogenesis of Blastocystis are due to pathogenic and nonpathogenic genotypes. Recent epidemiological, animal infection, and in vitro host-Blastocystis interaction studies suggest that this may indeed be the case. This review focuses on such recent advances and also provides updates on laboratory and clinical aspects of Blastocystis spp.

New insights on classification, identification, and clinical relevance of Blastocystis spp.

Background: The aim of this study is to describe the major evolutionary historical events among Leishmania, sandflies, and the associated animal reservoirs in detail, in accordance with the geographical evolution of the Earth, which has not been previously discussed on a large scale.
Methodology and Principal Findings
Leishmania and sandfly classification has always been a controversial matter, and the increasing number of species currently described further complicates this issue. Despite several hypotheses on the origin, evolution, and distribution of Leishmania and sandflies in the Old and New World, no consistent agreement exists regarding dissemination of the actors that play roles in leishmaniasis. For this purpose, we present here three centuries of research on sandflies and Leishmania descriptions, as well as a complete description of Leishmania and sandfly fossils and the emergence date of each Leishmania and sandfly group during different geographical periods, from 550 million years ago until now. We discuss critically the different approaches that were used for Leishmana and sandfly classification and their synonymies, proposing an updated classification for each species of Leishmania and sandfly. We update information on the current distribution and dispersion of different species of Leishmania (53), sandflies (more than 800 at genus or subgenus level), and animal reservoirs in each of the following geographical ecozones: Palearctic, Nearctic, Neotropic, Afrotropical, Oriental, Malagasy, and Australian. We propose an updated list of the potential and proven sandfly vectors for each Leishmania species in the Old and New World. Finally, we address a classical question about digenetic Leishmania evolution: which was the first host, a vertebrate or an invertebrate?
Conclusions and Significance: We propose an updated view of events that have played important roles in the geographical dispersion of sandflies, in relation to both the Leishmania species they transmit and the animal reservoirs of the parasites.

/pdf/a-historical-overview-of-the-classification-evolution-and-28b68wqwj0.pdf

A Historical Overview of the Classification, Evolution, and Dispersion of Leishmania Parasites and Sandflies

Phlebotomine sandflies transmit pathogens that affect humans and animals worldwide. We review the roles of phlebotomines in the spreading of leishmaniases, sandfly fever, summer meningitis, vesicular stomatitis, Chandipura virus encephalitis and Carrion's disease. Among over 800 species of sandfly recorded, 98 are proven or suspected vectors of human leishmaniases; these include 42 Phlebotomus species in the Old World and 56 Lutzomyia species in the New World (all: Diptera: Psychodidae). Based on incrimination criteria, we provide an updated list of proven or suspected vector species by endemic country where data are available. Increases in sandfly diffusion and density resulting from increases in breeding sites and blood sources, and the interruption of vector control activities contribute to the spreading of leishmaniasis in the settings of human migration, deforestation, urbanization and conflict. In addition, climatic changes can be expected to affect the density and dispersion of sandflies. Phlebovirus infections and diseases are present in large areas of the Old World, especially in the Mediterranean subregion, in which virus diversity has proven to be higher than initially suspected. Vesiculovirus diseases are important to livestock and humans in the southeastern U.S.A. and Latin America, and represent emerging human threats in parts of India. Carrion's disease, formerly restricted to regions of elevated altitude in Peru, Ecuador and Colombia, has shown recent expansion to non-endemic areas of the Amazon basin.

https://onlinelibrary.wiley.com/doi/epdf/10.1111/j.1365-2915.2012.01034.x

Phlebotomine sandflies and the spreading of leishmaniases and other diseases of public health concern

A polymerase chain reaction and single-strand conformation polymorphism determination (PCR-SSCP) was used to detect deoxyribonucleic acid sequence polymorphisms in the transcribed non-coding regions between the small and large sub-unit ribosomal ribonucleic acid (rRNA) genes in Leishmania donovani from 63 clinical samples collected in eastern Sudan, between April 1997 and October 1998. Specific Leishmania primers were used to amplify the internal transcribed spacer (ITS) regions of L. donovani isolates directly from clinical samples spotted on filter papers. Amplification products were subsequently analysed by SSCP. Eleven polymorphic patterns were detected in the first part of the spacer, the ITS1 region, and were sequenced. Most of the changes were due to deletions of adenine bases and AT pairs within the first 192 nucleotides of the ITS region. This is the first application of PCR-linked SSCP analysis for the detection of population variation with direct display of sequence variation in parasitologically positive clinical samples spotted on filter paper. Culturing the parasite is thus not required, which is beneficial particularly in epidemiological studies based on field work where obtaining cultures can be extremely difficult.

Genetic heterogeneity of ribosomal internal transcribed spacer in clinical samples of Leishmania donovani spotted on filter paper as revealed by single-strand conformation polymorphisms and sequencing.

OBJECTIVES To examine the presence of intestinal protozoan and helminth infections and their association with clinical signs and symptoms in children in Trujillo, Venezuela. METHODS Conventional microscopic methods (thick-smear, saline and iodine solutions) were used to identify parasites in stool samples of 301 children attending day care centres. A subgroup of 45 children was evaluated clinically and parasitologically five times during a 1-month period using conventional methods and the Kinyoun acid-fast stain for Cryptosporidium identification. RESULTS The point prevalence of protozoan infections was 21% for Giardia duodenalis, 1.0% for Entamoeba histolytica/dispar, 4% for Entamoeba coli, 16% for Blastocystis hominis, and 89% for Cryptosporidium parvum. Prevalence of helminth infection was 11% for Ascaris lumbricoides, 10% for Trichuris trichiura, 0.3% for Strongyloides stercoralis, and 1.3% for Hymenolepis nana. Over a 1-month time frame, new infections were observed at a rate of 11% for G. duodenalis, 4% for E. histolytica/dispar, 7% for A. lumbricoides, 11% for T. trichiura, 0% for S. stercoralis, and 2% for H. nana. Intestinal symptoms (diarrhoea, vomiting, gas, stomach pain, and loss of appetite) were associated with presence of one or more of C. parvum or B. hominis organisms in stool samples. CONCLUSIONS Intestinal parasitic infections contribute significantly to the enteric disease burden experienced by this group of children. The organisms most strongly implicated by this study are common and difficult-to-treat protozoan pathogens.

https://onlinelibrary.wiley.com/doi/pdf/10.1046/j.1365-3156.2003.01011.x

Intestinal parasitic infection and associated symptoms in children attending day care centres in Trujillo, Venezuela.

Identification of new world Leishmania using ribosomal gene spacer probes

By using a PCR assay specific for Leishmania braziliensis in blood samples, we detected this parasite in patients cured by immunotherapy or at different stages of treatment. We also found the parasite in subjects who had never suffered leishmaniasis but who had lived in endemic areas and migrated to nonendemic ones many years ago. These results suggest that L. braziliensis infections are difficult to eradicate and that a clinical cure but rarely a complete elimination of the parasite is generally accomplished.

Presence of Leishmania braziliensis in blood samples from cured patients or at different stages of immunotherapy.

We designed a PCR assay targeted on repeated elements of the ribosomal intergenic spacer which produces highly polymorphic DNA band patterns for different strains of Trypanosoma cruzi. By labeling the PCR products with digoxigenin and by chemiluminescence detection, we improved the assay sensitivity by three orders of magnitude to get T. cruzi strain fingerprints in feces of the trypanosome-infected triatomine bug vector. We also developed a capture assay for the digoxigenin-labeled PCR products that allowed us to detect T. cruzi in triatomine bug vector feces and in human serum samples with a solid support.

https://jcm.asm.org/content/jcm/32/1/153.full.pdf

Identification and detection of Trypanosoma cruzi by using a DNA amplification fingerprint obtained from the ribosomal intergenic spacer.

A new form of Leishmania is described from the Venezuelan Andes region. L. garnhami n.sp. is proposed for this parasite with amastigote stages showing a peculiar and unique organelle seen with light and electron microscope. It produces cutaneous lesions in people living at a height of between 800 and 1,800 m. in urban and rural areas; the disease is associated with Lutzomyia townsendi , the main anthropophilic sandfly in the region. The parasite is easily inoculable into hamsters and grows slowly in vitro in blood-agar media with glucose, but more prolifically without glucose.

José V. Scorza

Papers

Intestinal parasitic infection and associated symptoms in children attending day care centres in Trujillo, Venezuela.

Identification of new world Leishmania using ribosomal gene spacer probes

Presence of Leishmania braziliensis in blood samples from cured patients or at different stages of immunotherapy.

Identification and detection of Trypanosoma cruzi by using a DNA amplification fingerprint obtained from the ribosomal intergenic spacer.

A new species of Leishmania parasite from the Venezuelan Andes region.