This study undertook the first investigation of malacosporean infections in Neotropical fish. We used polymerase chain reaction detection with a primer set generally targeting known malacosporeans to assay for infection in the kidney of 146 fish in 21 species belonging to 12 families collected from two areas in the Amazon Basin. Infections were found in 13 fish variously belonging to seven species in six families and included the first identification of a malacosporean infection in cartilaginous fish (a freshwater stingray). Based on ssrDNA, all infections represented a single Buddenbrockia species (Buddenbrockia sp. E) that demonstrates an exceptionally broad range of fish species infected, and countered our expectations of high Neotropical malacosporean diversity. Infections were characterized at varying and often high prevalences in fish species but sample sizes were small. Ascertaining whether highly divergent malacosporeans have not been detected by current primers, and more comprehensive sampling may reveal whether malacosporeans are truly as species poor in the Amazon Basin as present data suggest. Our results prompt speculations about evolutionary scenarios including introduction via marine incursions and patterns of host use over time.

Saccocoelioides is a genus of trematodes associated with fishes from the Americas. In the current research, morphologically distinct specimens of Saccocoelioides spp. were collected from six countries in Middle America. Specimens were sequenced using three molecular markers, the domains D1–D3 of the large subunit (LSU) from the nuclear rDNA, the cytochrome c oxidase subunit 1 (cox1) and nicotinamide adenine dinucleotide dehydrogenase subunit 1 (nad1) from mitochondrial DNA. A total of 74 new sequences were compared and aligned with other sequences available in GenBank. Maximum likelihood and Bayesian inference analyses were inferred from the LSU and cox1 datasets, revealing unequivocally that all the specimens correspond to S. lamothei. A haplotype network was built with 119 sequences of the nad1 gene. The network detected 57 distinct haplotypes divided into three haplogroups. To explore morphological differences among samples of S. lamothei, 17 morphological features were measured from 53 specimens from three fish families: Eleotridae, Mugilidae and Gobiidae. Principal component analysis yielded three main polygons that corresponded with each family analysed, suggesting host-induced phenotypic plasticity. The current evidence suggests that S. lamothei infects at least five fish families along the Pacific coasts of Mexico, Guatemala, El Salvador, Honduras, Nicaragua and Costa Rica.

Since the discovery of Perkinsus marinus as the cause of dermo disease in Crassostrea virginica, salinity and temperature have been identified as the main environmental drivers of parasite prevalence. However, little is known about how these variables affect the movement of the parasite from host to water column. In order to elucidate how environmental factors can influence the abundance of this parasite in the water column, we conducted a series of experiments testing the effects of time of day, temperature and salinity on the release of P. marinus cells from infected oysters. We found that P. marinus cells were released on a diurnal cycle, with most cells released during the hottest and brightest period of the day (12:00–18:00). Temperature also had a strong and immediate effect on the number of cells released, but salinity did not, only influencing the intensity of infection over the course of several months. Taken together, our results demonstrate that (1) the number of parasites in the water column fluctuates according to a diurnal cycle, (2) temperature and salinity act on different timescales to influence parasite abundance, and (3) live infected oysters may substantially contribute to the abundance of transmissive parasites in the water column under particular environmental conditions.

The soil-transmitted helminth Ascaris lumbricoides infects ~800 million people worldwide. Some people are heavily infected, harbouring many worms, whereas others are only lightly infected. The mechanisms behind this difference are unknown. We used a mouse model of hepatic resistance to Ascaris, with C57BL/6J mice as a model for heavy infection and CBA/Ca mice as a model for light infection. The mice were infected with the porcine ascarid, Ascaris suum or the human ascarid, A. lumbricoides and immune cells in their livers and spleens were enumerated using flow cytometry. Compared to uninfected C57BL/6J mice, uninfected CBA/Ca mice had higher splenic CD4+ and γδ T cell counts and lower hepatic eosinophil, Kupffer cell and B cell counts. Infection with A. suum led to expansions of eosinophils, Kupffer cells, monocytes and dendritic cells in the livers of both mouse strains and depletions of hepatic natural killer (NK) cells in CBA/Ca mice only. Infection with A. lumbricoides led to expansions of hepatic eosinophils, monocytes and dendritic cells and depletions of CD8+, αβ, NK and NK T cells in CBA/Ca mice, but not in C57BL/6J mice where only monocytes expanded. Thus, susceptibility and resistance to Ascaris infection are governed, in part, by the hepatic immune system.

This epidemiological study assesses the occurrence of enteric parasites in 4303 patients attended at two public hospitals in Ankara (Turkey) during 2018–2019. Microscopy was used as a screening test. Giardia duodenalis was also identified using a commercial ELISA for the detection of parasite-specific coproantigens. Giardia-positive samples by microscopy/ELISA were confirmed by real-time PCR and characterized using a multilocus genotyping scheme. Blastocystis sp. was genotyped in a sample subset. Blastocystis sp. (11.1%, 95% CI 11.4‒14.8%) and G. duodenalis (1.56%, 95% CI 1.22‒1.96) were the most prevalent pathogens found. Cryptosporidium spp., Entamoeba histolytica and intestinal helminths were only sporadically (<0.5%) found. For G. duodenalis, sequence (n = 30) analyses revealed the presence of sub-assemblages AII (23.3%), discordant AII/AIII (23.3%) and mixed AII + AIII (6.7%) within assemblage A, and BIII (10.0%), BIV (3.3%) and discordant BIII/BIV (23.3%) within assemblage B. Two additional sequences (6.7%) were assigned to the latter assemblage but sub-assemblage information was unknown. No associations between G. duodenalis assemblages/sub-assemblages and sociodemographic and clinical variables could be demonstrated. For Blastocystis sp., sequence (n = 6) analyses identified subtypes ST1, ST2 and ST3 at equal proportions. This is the first molecular characterization of G. duodenalis based on MLG conducted in Turkey to date.

In the endemic countries, human cystic echinococcosis (CE) poses a serious medical and social problem. Because it most often affects the liver and lungs we aimed to define the proportion of cases with different organ localization, the diagnostic and therapeutic approaches in such cases, and the outcome of them. For a period 2010–2019, a total of 2863 cases of CE were registered in Bulgaria, of which 148 (5.17%) with organ localization other than liver and/or lung. The majority of patients with extra-hepatopulmonary localization of CE were adults. The distribution by gender showed predominance of female patients (57.43%) over those of males and primary cases (85.14%) exceeded the cases of recurrence. According to our study most common is the spleen involvement, followed by involvement of the abdominal cavity, kidneys and muscle/subcutaneous tissue. Other extra-hepatopulmonary organ localizations are significantly less common. This study shows that the extra-hepatopulmonary localization of CE is not so rare, and in most cases it is a primary disease. In respect of this, clinicians should consider hydatidosis in the differential diagnosis when cystic formation(s) is found, regardless of the organ involved.

Chagas disease is a serious parasitic infection caused by Trypanosoma cruzi. Unfortunately, the current chemotherapeutic tools are not enough to combat the infection. The aim of this study was to evaluate the trypanocidal activity of benznidazole-loaded microparticles during the acute phase of Chagas infection in an experimental murine model. Microparticles were prepared by spray-drying using copolymers derived from esters of acrylic and methacrylic acids as carriers. Dissolution efficiency of the formulations was up to 3.80-fold greater than that of raw benznidazole. Stability assay showed no significant difference (P > 0.05) in the loading capacity of microparticles for 3 years. Cell cultures showed no visible morphological changes or destabilization of the cell membrane nor haemolysis was observed in defibrinated human blood after microparticles treatment. Mice with acute lethal infection survived 100% after 30 days of treatment with benznidazole microparticles (50 mg kg−1 day−1). Furthermore, no detectable parasite load measured by quantitative polymerase chain reaction and lower levels of T. cruzi-specific antibodies by enzyme-linked immunosorbent assay were found in those mice. A significant decrease in the inflammation of heart tissue after treatment with these microparticles was observed, in comparison with the inflammatory damage observed in both infected mice treated with raw benznidazole and untreated infected mice. Therefore, these polymeric formulations are an attractive approach to treat Chagas disease.

Cutaneous Leishmaniasis (CL) is considered a neglected tropical disease which in Pakistan can now be considered as a growing public health problem. The exact figures on the magnitude of the disease are lacking both at the national and regional level and only a few health centres are available for diagnosis of CL. The present study was designed to identify the epidemiology of CL infection from August 2018 to December 2019 and to assess clinical aspects of CL in Baluchistan Province of Pakistan. A total of 4072 clinically suspected CL cases were analysed statistically. The highest number of CL cases were reported in May, followed by April, January and then July, February and June and the lowest number of cases were observed in March and November. The highest prevalence rate was found in males where 38% of reported cases were aged 0–9 years. The majority (24.4%) of lesions were found on the hands followed by the face in which cheeks, ears and nose were the effected organs. About 50% of the participants have single lesion while 14% of the participants had two and nearly 3% of the participants have six lesions. The atypical clinical presentations were observed in Baluchistan and common unusual presentations were lupus erythematosus. The study findings suggest that more epidemiological studies and health education campaigns are needed for the population awareness regarding CL in Baluchistan. It is recommended that risk factors should be evaluated to establish control and management strategies to prevent disease at the individual and community level.

This work introduces new morphological and molecular information on the filaroid nematode Setaria cervi (Rudolphi, 1819) obtained from 13 infected game ungulates out of 96 dissected. The hosts comprised the following: a single moose (Alces alces), ten red deer (Cervus elaphus) and two sika deer (Cervus nippon) originating from the western and northern regions of the Czech Republic. Based on the complete sequences of the gene encoding mitochondrial cytochrome c oxidase subunit 1 (cox1), all 20 females and four males belonged to the species S. cervi. We detected three developmental female stages (adult fertile females, juvenile L5 females and L4 female larvae) differing in size and some morphological traits as the subtle structure of peribuccal crown and shape and features of tail knob. Such differences were described in detail for the first time. The phylogenetic relationships within the family Onchocercidae have been evaluated using new information on the cox1 sequence of S. cervi (maximum likelihood method, GTR + I + G model). In accordance with the latest phylogenetic studies, the present analysis confirmed the ancient separation of the subclass Setariinae from the remaining two onchocercid lineages Dirofilariinae and Onchocerinae.

The swimbladder functions as a hydrostatic organ in most bony fishes, including the European eel, Anguilla anguilla. Infection by the nematode Anguillicoloides crassus impairs swimbladder function, significantly compromising the success of the eel spawning migration. Swimbladders from 32 yellow eels taken from Lake Trasimeno (Central Italy) were analysed by histopathology- and electron microscopy-based techniques. Sixteen eels (50%) harboured A. crassus in their swimbladders and intensity of infection ranged from 2 to 17 adult nematodes per organ (6.9 ± 1.6, mean ± s.e.). Gross observations of heavily infected swimbladders showed opacity and histological analysis found a papillose aspect to the mucosa and hyperplasia of the lamina propria, muscularis mucosae and submucosa. Inflammation, haemorrhages, dilation of blood vessels and epithelial erosion were common in infected swimbladders. In the epithelium of parasitized swimbladders, many empty spaces and lack of apical junctional complexes were frequent among the gas gland cells. In heavily infected swimbladders, we observed hyperplasia, cellular swelling and abundant vacuolization in the apical portion of the gas gland cells. Numerous mast cells and several macrophage aggregates were noticed in the mucosal layer of infected swimbladders. We found more nervous and endocrine elements immunoreactive to a panel of six rabbit polyclonal antibodies in infected swimbladders compared to uninfected.

The present work aimed at studying the efficacy of mebendazole (MBZ) compared to artemisinin (ART) for the treatment of trichinellosis at various phases of infection. Seventy Swiss albino mice were orally infected by 300 Trichinella spiralis (T. spiralis) larvae. Mice were divided into infected untreated control group and infected groups treated with 50 mg kg−1 MBZ and 300 mg kg−1 ART for three and five consecutive days, respectively, at the enteral phase [2–4 days post infection (PI)], invasive phase (10–12 days PI) and encapsulated phase (28–30 days PI). All mice were sacrificed 35–42 days PI. MBZ and ART revealed a significant decrease in mean larval counts and increase of larval per cent reduction (LR %) when treatment was initiated during the enteral phase compared to the other phases. MBZ showed significantly higher LR % (99.7, 83.95 and 89.65%) than ART (80.58, 67.0 and 79.2%) when administered at the three infection phases. Histopathological study showed a decrease in the number of encysted larvae, their surrounding cellular infiltrates and increased regenerative muscles in all treated mice. In conclusion, ART possesses a substantial anthelmintic activity against T. spiralis infection in mice both at the enteral and encapsulated phases, yet, significantly lower than MBZ.