Parasitologia

The common gull (Larus canus) and the black-headed gull (Larus ridibundus) are common waterbird species in Lithuania. Until now, the composition of Sarcocystis species in these birds was unknown. The current study aimed to identify Sarcocystis spp. by the morphological examination of sarcocysts found in the muscle tissues and by DNA sequence analysis. Between 2011 and 2019, the leg muscles of 42 common gulls and 63 black-headed gulls were tested for Sarcocystis spp. Based on the methylene blue staining of squashed muscle samples, sarcocysts were detected in six common gulls (14.3%) and in six black-headed gulls (9.5%). Under a light microscope, one type of microcyst was observed. Sarcocysts were thread-like (2860–8250 × 40–180 μm) and had a smooth and thin (0.8–1.4 μm) cyst wall, while bradyzoites were banana-shaped and 5.0–9.2 × 1.3–2.4 μm in size. The sequencing of complete ITS1 showed the presence of S. columbae, S. halieti and S. wobeseri in the common gull and S. columbae and S. halieti in the black-headed gull. The highest intraspecific genetic variability was established for S. halieti, which is characterized by a wide host range. This species is considered to be pathogenic, therefore further histopathological examination of the various organs of gulls is needed. Full article

Eosinophilia is common in low-resource countries and usually implies helminthiasis. Since helminthiasis is a common cause of eosinophilia and its diagnosis is cumbersome, we hypothesized that broad-spectrum anthelmintic therapy may decrease the eosinophil count and eventually cure helminthiasis, whether microbiologic diagnosis is established or not. We recruited patients with eosinophilia aged 5 years and older who presented to Dhulikhel hospital, Nepal. Patients were treated with albendazole and ivermectin. A stool sample for microscopy was obtained. Of a total of 113 patients, 106 had a follow-up visit and 56 were classified as responders to treatment (defined as a decrease in eosinophil count to below 500 cells/µL, or an absolute decrease of more than 1000 cells/µL). For all patients, we found an absolute decrease in the eosinophil count and for the responding group (more than 50% of the whole cohort), the eosinophil count decreased substantially. All stool samples were negative. The reason for a lack of response in the remaining patients is unclear. In order to ascertain whether eosinophilia should be an indication for anthelmintic treatment, a randomized controlled study of empirical treatment after a thorough microbiologic workup is needed. Full article

(1) Intestinal microbial parasites are major contributors to the global burden of gastrointestinal disease. Such infections are mainly caused by Cryptosporidium, Giardia duodenalis, and Entamoeba histolytica. These parasites are transmitted either directly or indirectly through oral–fecal routes. Previous reports suggested that camels could play a role in the zoonotic transmission of various clinically and veterinary important intestinal parasites, however, limited data are available on intestinal infections of camels, particularly on a molecular level. We aimed to explore the occurrence of these three parasites in camels (Camelus dromedarius) in Algeria. (2) A total of 68 samples—63 stool samples from camels and five from the environment—were collected from two desert regions in Algeria and analyzed using PCR and qPCR methods. (3) Overall, 7% of the camels tested positive for zoonotic subtypes of Cryptosporidium spp., while 16% of the camels tested positive for G. duodenalis. Two environmental samples also tested positive for G. duodenalis. None of the samples were positive for Entamoeba histolytica. (4) Our results provide one of the first molecular-based identification of these gut parasites in dromedary camels in Algeria. The presence of G. duodenalis in the host and the environment unveils, in part, the circulation route of this parasite. Our results will spearhead further investigations into the prevalence and epidemiology of gut parasites in hoofed animals and raise questions concerning their role in health and disease in the area. Full article

Toxoplasmosis in immunocompromised patients results in either reactivation of latent toxoplasmosis or acute infection. In the framework of the kidney transplantation program in Senegal, the serological screening of potential pre-transplant and transplanted patients can prevent the disease. This study aimed to assess the seroprevalence of toxoplasmosis in a cohort of hemodialysis patients, candidates for kidney transplantation. To this end, a multicentre cross-sectional study was conducted in 2020 in six dialysis units from five regions. Blood samples and sociodemographic data were collected from each patient. IgG and IgM against T. gondii antibodies were assessed by a chemiluminescent method using Architect ci4100, and statistical analysis was performed using R software. Overall, 211 hemodialysis patients aged from 18 to 77 years were enrolled. The mean age was 42.62 years ± 13.6, and the sex ratio M/F was 1.24. The overall seroprevalence of T. gondii was 41.7%, with the highest value being recorded in the region of Kaolack (44.4%). Patients aged over 60 years were more typically infected, at a proportion of 56.0%. Regarding sex, males elicited a higher prevalence (44.4.%) than females did. Patients of an upper socioeconomic status were less affected, and contact with cats was not associated with toxoplasmosis. By education level, the illiterate group was most affected one. Overall, this first study of toxoplasmosis among Senegalese hemodialysis patients indicates high seroprevalence. Full article

Many new marine parasite species are added every year. Still, in some places, mainly tropical regions, marine parasites have been little studied. An exhaustive review of the indexed publications where species of parasites are reported in the marine environments of Costa Rica was carried out. The history of research on marine parasites in this region is also reviewed. A total of 147 species of marine parasites have been reported in Costa Rica as parasites of 61 different species of hosts. Most of these parasites correspond to trematodes and cestodes, found mainly in the digestive tract of their vertebrate hosts. In Costa Rica, marine parasites have been studied mainly in sea turtles, elasmobranchs, fish, and dolphins. Most marine parasites have been reported based on morphological identifications of adult stages, and most of the work done so far consists of taxonomic identifications (species reports), with little contribution to the pathology and other aspects of the parasites–hosts interactions. The technical difficulties for research in marine parasitology, the lack of sampling in certain groups of hosts, and the lack of a consolidated research group in marine wildlife parasitology in Costa Rica are factors that have prevented a greater and faster advance in the knowledge of the biodiversity of marine parasites in this country. Full article

Considering that health professionals at Brazil had doubts about the entomoepidemiological issues of Chagas disease (CD), and that many of them highlighted not feeling totally safe for clinical care, the knowledge of 281 Brazilian medical students was evaluated through a cross-sectional, descriptive, prospective, and quantitative research. Most students demonstrated that they knew about the etiological agent of CD (Trypanosoma cruzi), since 279 students answered the questionnaire correctly. Furthermore, the medical students demonstrated knowledge of the main form of transmission of the parasite, as 278 students associated CD transmission with triatomines. On the other hand, approximately 25 students did not associate CD transmission with triatomine feces. Besides that, these future health professionals had difficulties in relation to the treatment of CD, as more than half of the students (176) wrongly answered that CD “is not curable” or “is curable in the chronic phase”. Based on the results obtained that point out the difficulties medical students have with CD, there is a need for undergraduate medical courses to address the neglected diseases holistically because the National Curriculum Guidelines for the medical course require the training of competent health professionals capable of integrating the biological, psychological, social, and environmental dimensions. Full article

This study assessed the efficiency of a new in vitro tick feeding system for the adult Rhipicephalus appendiculatus tick and compared the impact of different blood anticoagulating factors on their feeding process. A total of 10 feeders were each seeded with 30 or 60 R. appendiculatus adults. Bovine blood was added into each unit and changed every 12 h for 4 to 10 days during which tick attachment and engorgement was assessed. The tick attachment observed 4 days after feeding was 80.0% (48/60), 75.8% (182/240), and 70.8% (170/240) for lithium heparin, citrate phosphate dextrose, and defibrinated blood, respectively, with no significant difference (p > 0.05) between the anticoagulants used. However, the ticks fed on heparinized and defibrinated blood reached repletion status. The in vitro tick feeding system was successfully used to feed adult R. appendiculatus ticks until repletion. This system could be used to facilitate studies on tick-pathogen interactions, such as those involved in the East Coast fever disease. Full article

Yellow fever (YF) is an emerging and re-emerging arboviral disease transmitted through the bites of infected Aedes mosquitoes, primarily in the genus Aedes. Several outbreaks of yellow fever have been documented in southern Ethiopia. Four outbreaks have been documented since 2012, suggesting that southern Ethiopia is prone to YF outbreaks. Understanding the transmission cycle is pivotal to managing arboviral disease outbreaks, and the aims of the present study were to investigate the mosquito species that most likely contributed to the recent YF outbreaks and to study their behaviors. Therefore, the present study aimed to evaluate which species of Aedes mosquitoes contribute to the YF virus transmission, the outbreaks that have occurred and their behaviors (biting and resting) in the region. Two districts were selected on the basis of recent YF outbreak history. A longitudinal entomological survey was conducted to collect adult mosquitoes by using human landing catches (HLC), mechanical mouth aspirators and pyrethrum sprays. Collections were conducted twice a month for six months, from February 2019 to July 2020. The mosquitoes were identified by species by using morphological keys and molecular techniques. A total of 1689 mosquitoes were collected, of which 93.7% (1582/1689) were members of the genus Aedes and 6.3% (107/1689) of the genus Culex. A total of 58.7% (991/1689) of the mosquitoes were captured in the Ofa District and 41.3% (698/1689) from the Boko Dawula District. The largest number of mosquitoes, 97.9% (1653/1689), were collected during the wet season. A total of 1582 members of the Aedes simpsoni complex were collected, where 57.7% (913/1582) were from the Ofa District and 42.3% (669/1582) were from the Boko Dawula District. Molecular identification showed that members of the Aedes simpsoni complex accounted for 99.5% (404/406), while Aedes aegypti, detected only in the Ofa District, accounted for only 0.5% (2/406). The mosquitoes were pooled and tested for YFV, dengue virus (DENV, serotype 1–4) and chikungunya virus (CHKV) by using qPCR. None of the 934 Aedes simpsoni tested were positive for any arboviruses. The human-biting activities of Ae. simpsoni complex were peaked between 8:00–9:00 and 16:00–17:00, mostly outdoors, both within the villages and the forests. The largest numbers of Aedes simpsoni complex resting mosquitoes were collected from the leaves of the Abyssinian banana, Ensete ventricosum, suggesting that they are the preferred resting places. Although the tested Ae. simpsoni complex was negative for arboviruses; the morning and afternoon activities of the species complex coincide with peak human outdoor activities in these areas and may therefore pose the highest risk of transmitting YFV to humans. The extremely low abundance of Aedes aegypti suggests a minor role in arbovirus transmission in southern Ethiopia. It is of great importance that expanded surveillance activities of arboviruses to include reservoir hosts and sylvatic vectors to the chances of devising and implementing effective control measures. Full article

Since the mid-1990s, male-only heartworm infections have been considered undetectable using antigen tests based on experimental studies. Results from those studies are in contrast to reports in the decade prior showing variable male heartworm antigen detection using naturally infected animals and antigen tests using chemical and/or heat immune complex dissociating steps. Several recent studies utilizing heat treatment for immune complex dissociation (Heat ICD) demonstrated increased antigen sensitivity for necropsy verified male-only infections and a higher-than-expected frequency of this type of infection. This study utilized archived canine serum with verified male-only heartworm infections to evaluate detection of the heartworm antigen using the DiroCHEK^® (Zoetis LLC, Parsippany, NJ, USA), Witness^® (Zoetis LLC, Parsippany, NJ, USA), and SNAP^® Heartworm RT (IDEXX Laboratories, Inc., Westbrook, ME, USA) antigen tests. Results showed significant increases in sensitivity for the heartworm antigen following heat treatment for DiroCHEK^® (+42.1%, p < 0.0001) and Witness^® (+26.3%, p = 0.0020), but not the SNAP^® Heartworm RT (+10.5%, p = 0.1250). Prior to heat treatment, false negative results were obtained in 76.3–83.0% of mature infections. Infections with only immature male worms were never detected using any heartworm test used. Heat treatment of serum allows improved detection of mature male-only heartworm infections, which may occur more frequently than previously recognized, and like all heartworm infections pose a risk of chronic and cumulative pathology as well as thromboembolic disease regardless of infection intensity. Full article

The Acanthamoeba genus comprises the free-living amoebae that are ubiquitously present as opportunistic pathogens. They cause serious human diseases—for instance, Acanthamoeba keratitis (AK), granulomatous amoebic encephalitis (GAE), cutaneous acanthamoebiasis and disseminated infections. The traditional method for classifying Acanthamoeba was based on the morphological examination of cysts. However, this method was less consistent as the morphology of cysts changes with the culture conditions. After the advent of molecular techniques, genotyping is considered an essential tool in accurately identifying Acanthamoeba at the species level and is further helpful in classification up to the sub-genotype level. The most recommended and currently used methods for Acanthamoeba genotyping are 18S and 16S rDNA gene sequencing. Based on these two genes, Acanthamoeba is classified into 23 genotypes. Out of these, it is the T4 genotype that is most commonly associated with clinical disease and isolation from environmental samples. The T4 genotype contains more than ten species within it. Differences in geographical distribution, virulence, pathogenesis and drug susceptibility profile have been observed among different genotypes. However, whether such differences exist within sub-genotypes/species under T4 is yet unknown. In the present study, 11 Acanthamoeba isolates, which were already characterized as the T4 genotype by the hypervariable region of diagnostic fragment 3 (DF3) of the 18S rDNA, were sub-genotyped using the 16S rDNA mitochondrial sequence. Nine of these were isolated from patients with AK and two from water samples. Phylogenetic analysis of these isolates attributed them to four sub-genotypes (T4a (n = 6), T4b (n = 1), T4_Neff (n = 2) and T4d (n = 2)). The study highlights the potential use of 16S in the sub-genotyping of Acanthamoeba T4. The 16S rDNA sequences of two isolates, one from an Acanthamoebic keratitis (AK) patient and one environmental, were found to group with A. mauritaniensis (T4d). This group was believed to be a non-pathogenic environmental Acanthamoeba and the identification of the AK isolate may be confirmed by whole-genome sequencing. Full article

Babesia vulpes is a small Babesia prevalent in foxes in Europe and mainly clinically affects dogs in north-western Spain. A dog imported from this region that had been living in Germany for three years developed splenic torsion. After splenectomy, the dog underwent immunosuppressive therapy because of autoimmune disease due to haemotrophic Mycoplasma sp. infection. As clinical signs worsened, small Babesia were detected in a blood smear and identified as B. vulpes by molecular analysis. Anaemia, thrombocytosis, elevated liver enzymes, and renal parameters were the most significant findings in blood analysis. The dog was treated with a combination of atovaquone (20 mg/kg BW, BID), proguanil hydrochloride (8 mg/kg BW, BID) and azithromycin (10 mg/kg BW, SID), which led to an increase in the cycle threshold in real-time PCR and the absence of B. vulpes in the blood smear. However, after clinical signs deteriorated, the dog was euthanised. This case report supports the recommendation to screen imported dogs for pathogens and highlights the impact of splenectomy on the course of infection. Full article

Due to frequent variations in environmental conditions, free-living amoebae adapt through differentiation into different states. Hence, favorable conditions enable the formation of a feeding and proliferative form named “Trophozoïte” whereas unfavorable situations drive differentiation into resting and resistant single forms such as cysts, spores, or multicellular structures. Transformation into cyst, named “encystment” or “encystation”, is a common feature found in testate, naked, or flagellated free-living amoebae. Although much effort has been made to understand encystment, several blind spots are still present. This short opinion paper highlights some difficulties impeding a better understanding of encystment. Full article

A 44-year-old human immunodeficiency virus-infected (HIV+) female with severe immunodeficiency Category 3 (C3) diagnosed in 2010 was admitted to hospital with acute diarrhoea. She was non-adherent to antiretroviral therapy (ART) and had a previous suspicion of respiratory symptoms with a cough that had been persisting for 15 days. Clinical examination revealed severe immune deterioration (viral load: 109,655 copies/mL; CD4+ count: 14 cells/mm3), respiratory symptoms (negative sputum Gram stain and tuberculosis culture), and neurological deterioration (serological assays negative for Cryptococcus spp. and Toxoplasma gondii). A coproculture was negative for Campylobacter spp., Salmonella spp., and Shigella spp. Ziehl–Neelsen staining of faecal smears revealed the presence of Cryptosporidium spp. oocysts. PCR testing and sequencing confirmed a concomitant infection with C. meleagridis and Enterocytozoon bieneusi. The patient was treated with metronidazole (500 mg every 8 h for 5 days) and nitazoxanide (500 mg every 12 h for 14 days). After requesting voluntary discharge and abandoning ART and parasiticidal treatments, she experienced a dramatic deterioration of her state of health and contact with her was lost. Our results have demonstrated that molecular-based testing improves the detection of opportunistic pathogens that are difficult to detect by routine microscopy, allows for transmission dynamics investigations, and assists in choosing the best chemotherapeutical option. Full article

Helminth parasites secrete several types of biomolecules to ensure their entry and survival in their hosts. The proteins secreted to the extracellular environment participate in the pathogenesis and anthelmintic immune responses. The aim of this work was to identify and functionally annotate the excretory/secretory (ES) proteins of the monogenean ectoparasite Rhabdosynochus viridisi through bioinformatic approaches. A total of 1655 putative ES proteins were identified, 513 (31%) were annotated in the UniProtKB/Swiss-Prot database, and 269 (16%) were mapped to 212 known protein domains and 710 GO terms. We identified six putative multifunctional proteins. A total of 556 ES proteins were mapped to 179 KEGG pathways and 136 KO. ECPred predicted 223 enzymes (13.5%) and 1315 non-enzyme proteins (79.5%) from the secretome of R. viridisi. A total of 1045 (63%) proteins were predicted as antigen with a threshold 0.5. We also identified six venom allergen-like proteins. Our results suggest that ES proteins from R. viridisi are involved in immune evasion strategies and some may contribute to immunogenicity. Full article

The Iberian Peninsula is one of the most humanized areas in Europe, yet humans may cohabit with large predators, such as the Iberian wolf (Canis lupus signatus), at the expense of many contributions to its conservation. The limited wolves’ territory leads to a close relationship between this wild species, humans, and other animals, which may promote the spillover of pathogens, such as gastrointestinal parasites. This review intends to provide an update concerning gastrointestinal parasite findings performed using coprological methods on fecal samples from Iberian wolves. Studies conducted in Portugal and Spain through coprology presented a prevalence of gastrointestinal parasites of 57.0–100% in Spain and 21.5–68.3% in Portugal. Parasites belonging to Protozoa, Trematoda, Cestoda, and Nematoda were specified, alongside thirteen genera and twenty species of gastrointestinal parasites. In this study, 76.9% (10/13) of genera and 65.0% (13/20) of species of gastrointestinal parasites were identified as having zoonotic potential. These results highlight that further studies are needed to better understand the parasitic agents circulating in the wild in humanized areas, such as the Iberian Peninsula. Full article

Infectious parasites, especially the intestinal protozoan parasites, continue to be a major public health problem in Africa, where many of the same factors contribute to the transmission of these parasites. This study was conducted to investigate the parasites causing intestinal protozoal infections diagnosed in Aristide Le Dantec hospital (Senegal). Direct examination and the Ritchie technique were used. Among the 3407 stool samples studied, 645 demonstrated the presence of intestinal protozoa in single parasitism, biparasitism, or polyparasitism, representing a prevalence of 18.93%. Out of a total of 645 protozoa, 579 (16.99%) were identified in monoparasitism in the following order: Entamoeba coli (6.87%) and Blastocystis hominis (5.69%) for low pathogenic species, and Entamoeba histolytica/dispar (2.31%) and Giardia intestinalis (1.32%) for pathogenic species. The rates of biparasitism and polyparasitism were 1.88% and 0.06%, respectively. The highest rate of parasites was 24.83% between the ages of 0–15 years. A logistical regression model indicated that intestinal protozoan infections were not associated with age groups. There was an association between age groups and Giardia intestinalis and Blastocystis hominis (p < 0.05). These results demonstrated the frequency of intestinal protozoa in Senegal. There is a need to implement treatment, prevention, and control measures to limit the circulation of these protozoan infections. Full article

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