Parasitologia, Volume 2, Issue 4 (December 2022) – 8 articles

Acute Chagas disease (ACD) caused by Trypanosoma cruzi has emerged as a major food-borne disease in Brazilian Amazonia. For the first time, we characterized an outbreak of orally acquired ACD in Acre, in the forest community of Seringal Miraflores, affecting 13 individuals who shared the pulp of açai palm berries: 11 adults and two children (one newborn), all diagnosed by thick-drop blood smears. The fluorescent fragment length barcoding method, which simultaneously identifies species/genotypes of trypanosomes in blood samples, uncovered an unprecedented genetic diversity in patients from a single outbreak of ACD: T. cruzi TcI in all patients, mostly concomitantly with the non-pathogenic Trypanosoma rangeli of genotypes TrA or TrB, and TcI, TcIV, and TrB in the child. The patients presented persistent fever, asthenia, myalgia, edema of the face and lower limbs, hepatosplenomegaly and, rarely, cardiac arrhythmia. The clinical symptoms were not correlated to gender, age, or to trypanosome species and genotypes. The inferred SSU rRNA phylogenetic analyses of trypanosomes from humans, triatomines and sylvatic hosts included the first sequences of T. cruzi and T. rangeli from humans in southwestern (Acre and Rondônia) Amazonia, and the first TcI/TcIV sequences from Rhodnius spp. from Acre. The sylvatic transmission cycles of genetically different trypanosomes in landscapes changed by deforestation for human settlements and increasing açai production is a novel scenario favoring trypanosome transmission to humans in Acre. Full article

Full-length cDNAs encoding macrophage inhibitory factor-2 (MIF-2) were cloned from Teladorsagia circumcincta (TcMIF-2) and Haemonchus contortus (HcMIF-2). TcMIF-2 and HcMIF-2 cDNA (342 bp) encoded proteins of 114 amino acids, each of which was present as a single band of about 16 kDa on SDS-PAGE. Multiple alignments of the protein sequences showed homology of 84% between TcMIF-2 and HcMIF-2, 54–76% with MIF-2s of seven nematodes, but low homology with other MIF sequences. The predicted three-dimensional structures revealed an overall structural homology of TcMIF-2 and HcMIF-2, highly conserved binding and catalytic sites and minor differences in the tautomerase binding site residues in other nematode MIF-2 homologues. A phylogenetic tree was constructed using helminth and mammalian MIF-1 and MIF-2 sequences. Soluble C-terminal MIF-2 proteins were cloned in arabinose inducible promotor AY2.4, expressed in Escherichia coli strain AY2.4 and purified. Recombinant TcMIF-2 and HcMIF-2 had similar enzyme activities in a standard tautomerase assay. Recombinant HcMIF-2 activity was approximately halved by storage at 4 °C, −20 °C or −70 °C. Antibodies in serum and saliva from field-immune, but not nematode-naïve, sheep recognised recombinant HcMIF-2 and TcMIF-2 in enzyme-linked immunosorbent assays. Recognition of the recombinant proteins by antibodies generated by exposure of sheep to the native enzyme indicates similar antigenicity of the two proteins. Full article

Cystic echinococcosis (CE) is endemic in Argentina, and approximately 30% of the national territory has characteristics appropriate for the development of the zoonotic domestic cycle of this disease. This community-wide study was implemented in rural areas of Añatuya, Santiago del Estero (northern Argentina) to determine the presence of Echinococcus granulosus sensu lato in the definitive host (dogs) and the presence of CE in humans. Infection data from dogs were obtained through the collection and analysis of fecal samples; these were processed through sedimentation/flotation techniques and PCR. The presence in humans was determined by ultrasound (US) and serology (ELISA confirmed by Western Blot—WB) in the Miel de Palo settlement. A standardized questionnaire was used to investigate potential risk factors for CE; more than half of the studied population carried out activities that favor the maintenance of the cycle. The prevalence of E. granulosus s.l. in dogs from 10 rural settlements, confirmed by PCR, was 4.7% (32/678). The results of the US and serology screening showed a human prevalence of 0.55% (1/183) in Miel de Palo. This prevalence increased to 4.9% (9/183) if imaging-negative but serology-positive (ELISA+WB) individuals are included, as per national guidelines. One of the participants with CE, confirmed by US, was less than 15 years old, which evidences the presence of active transmission. A comprehensive multidisciplinary approach, taking into consideration social, behavioral, sanitary, and environmental aspects intimately tied to the parasite cycle, is needed. Full article

Hematophagous leeches express a broad variety of secretory factors in their salivary glands; among them are hirudins, inhibitors of blood coagulation, and decorsins/ornatins, inhibitors of platelet aggregation. Here, we describe the identification and molecular and functional characterization of putative hirudins and decorsins/ornatins in two leech species of American origin, Limnobdella mexicana and Haementeria vizottoi. The leech species represent two orders of leeches, the proboscis-bearing Rhynchobdellida and the non-proboscis-bearing Arhynchobdellida. Members of the hirudin superfamily, such as hirudins or decorsins/ornatins, are described for the first time in the genus Haementeria. Both species expressed very potent inhibitors of platelet aggregation, but only the putative hirudins of L. mexicana displayed high thrombin-inhibitory potency, whereas the putative hirudin of H. vizottoi turned out to be a hirudin-like factor. The results of our study provide new insights into the evolutionary background of the blood-sucking lifestyle in leeches. Full article

Japanese encephalitis virus (JEV) is a mosquito-borne virus primarily found in Asia and Australia and is one of the few with an associated human/animal vaccine. Swine are amplifying hosts and wading birds are reservoirs of JEV, while horses and humans are incidental hosts. The primary vector is Culex tritaeniorhynchus, a generalist blood feeder not found in the United States (US); secondary vectors (e.g., Cx. pipiens, Cx. quinquefasciatus, Aedes japonicus, Ae. vexans) are widespread in the US (including North Carolina [NC]). The risk of JEV to NC was investigated because of widespread swine production, human populations, bird hosts, and possible mosquito vectors; however, recommendations can also apply to other swine producing states and regions. A brief review was conducted to identify transmission competent arthropod vectors, vertebrate hosts, and vector-host interactions for JEV. NC and other areas may be at risk for JEV emergence because of factors such as active international trade, volume of swine production, permissive climate, and widespread occurrence of potential vector species. Improved knowledge of the spatial distribution of swine farms, tracking movement of live swine, assessment of vector competence/capacity and blood feeding habits of potential JEV vectors, investigation of a JEV sentinel surveillance system, and assessment of efficacy for current biosecurity and control measures is needed to protect public and veterinary health. Full article

Introduction: Blastocystis sp. is a unicellular obligate anaerobic protozoa found in the human intestinal tract. Its role in human health is widely discussed because of the high proportion of asymptomatic carriers. In sub-Saharan Africa, the prevalence of the disease is underestimated. This study was performed to describe the epidemiological, clinical, and parasitological aspects of Blastocystis sp. infection in patients attending to Fann University Hospital. Material and Methods: We carried out a retrospective and descriptive study among patients attending to the laboratory of Parasitology and Mycology of Fann University Hospital from January 2016 to December 2020. All stool samples collected were examined using direct examination, a formal ether concentration method, and a modified Zeilh–Nielsen staining method. A descriptive analysis was performed with Stata MP 16 software. The significance level was set at 5%. Results: Overall, 447 cases of Blastocystis sp. were reported in our study, representing a prevalence rate of 13.7% ((447/3264) (95% CI: 12.5–15.5)). The mean age of the patients was 26 ± 20.7 years. Subjects over 45 years of age were more affected, with a frequency of 14.7%. Blastocystis sp. carriage was more common in males, at 14.6%. The symptomatology was mainly represented by diarrhea, abdominal pain, and dyspeptic disorders. In asymptomatic patients, the frequency of Blastocystis sp. was 33.3%. Mono-infection was found in 78.6% of cases. In total, 96 patients were carriers of at least two parasites (21.5%). Blastocystis sp. was most associated with Entamoeba coli (8.1%) and Endolimax nanus (4.03%). The association with helminths was noted in 5 patients (3 Ascaris lumbricoides, Trichuris trichiura, and Taenia). Conclusion: These results show the frequency of Blastocystis sp. infection with a large proportion of asymptomatic carriers. The presence of the parasite in the stool, associated with digestive disorders or with the association of other intestinal parasites, could justify the initiation of an anti-parasitic treatment. Full article

The rapid growth in the human population has led to an increased requirement for readily available food sources. The aquaculture industry is a fundamental source for maintaining food supplies; however, it is subjected to mounting pressures to meet supply demands. Thus, limiting factors that negatively impact the cultivation of farmed aquatic organisms is essential. Gill disease is an increasing area of concern, resulting in substantial losses in farmed fish. Several microbial pathogens are known to cause gill disease and, in many instances, multiple pathogens or factors can be involved in the disease, resulting in complex gill disease (CGD). The role of mixed infections in gill disease is largely unknown, as such this review aims to examine data on previous infections and highlight the variety of microbes that might be involved in gill disease. The influence of climate change in the context of CGD is also discussed given the strong links between physicochemical extremes and numerous microbial gill pathogens. Understanding these factors will allow for improved diagnostic and therapeutic strategies to be implemented. Full article

Populations of Triatomas infestans with different susceptibility to pyrethroid insecticides were reported to have distinct evolutionary and epidemiological characteristics. We aimed at evaluating metacyclogenesis and parasite load as measures of vector competence and feeding/defecation patterns as vectorial capacity estimates of a group of resistant (“R”) and susceptible (“S”) T. infestans. Third instar nymphs of each group were fed on mice infected with Trypanosoma cruzi (Tulahuén strain, DTU VI). Parasite concentration in blood was quantified by real-time PCR (qPCR) for each mouse. The time at which feeding started, the span of feeding, the volume of blood consumed, and the time taken to defecate were measured. At 30 days post-feeding, feces were analyzed in parallel by optical microscopy (percentage of metacyclic trypomastigotes, % MT), and qPCR (total T. cruzi DNA). The ratio of parasites consumed/defecated by nymphs of each group was used to estimate the parasites’ survival and multiplication inside the triatomines’ gut. It was estimated that for each blood trypomastigote consumed, 6.6 parasites were obtained in the feces of “R” nymphs, and 7.9 in “S”. “R” nymphs consumed a higher volume of blood, had lower % MT in their feces (lower vectorial competence), and took longer to defecate (lower vectorial capacity) than “S”. Full article