This study investigated relationships between organohalogen compound (OHC) exposure, feeding habits, and pathogen exposure in a recovering population of Atlantic walruses (Odobenus rosmarus rosmarus) from the Svalbard Archipelago, Norway. Various samples were collected from 39 free-living, apparently healthy, adult male walruses immobilised at three sampling locations during the summers of 2014 and 2015. Concentrations of lipophilic compounds (polychlorinated biphenyls, organochlorine pesticides and polybrominated diphenyl ethers) were analysed in blubber samples, and concentrations of perfluoroalkylated substances (PFASs) were determined in plasma samples. Stable isotopes of carbon and nitrogen were measured in seven tissue types and surveys for three infectious pathogens were conducted. Despite an overall decline in lipophilic compound concentrations since this population was last studied (2006), the contaminant pattern was similar, including extremely large inter-individual variation. Stable isotope ratios of carbon and nitrogen showed that the variation in OHC concentrations could not be explained by some walruses consuming higher trophic level diets, since all animals were found to feed at a similar trophic level. Antibodies against the bacteria Brucella spp. and the parasite Toxoplasma gondii were detected in 26% and 15% of the walruses, respectively. Given the absence of seal-predation, T. gondii exposure likely took place via the consumption of contaminated bivalves. The source of exposure to Brucella spp. in walruses is still unknown. Parapoxvirus DNA was detected in a single individual, representing the first documented evidence of parapoxvirus in wild walruses. Antibody prevalence was not related to contaminant exposure. Despite this, dynamic relationships between diet composition, contaminant bioaccumulation and pathogen exposure warrant continuing attention given the likelihood of climate change induced habitat and food web changes, and consequently OHC exposure, for Svalbard walruses in the coming decades.

A combination of idealised modelling and satellite imagery has been used to assess the dispersal of estuarine plume water and suspended material throughout the ecologically significant marine area off the west coast of the central North Island, New Zealand. The idealised modelling was used to elucidate the relative importance of oceanographic and meteorological conditions in controlling the horizontal structure of the estuary plumes, and then compared to plumes visible in satellite imagery and environmental monitoring data. Under low to average river flows the plumes can be categorised as either non-rotational or rotational. Rotational plumes are directed southwards under light (<5 m/s SW or <10 m/s E) winds and northwards under stronger (>5 m/s SW) winds. Non-rotational plumes remain close to the estuary mouth. The type, orientation and extent of the plumes have implications for estuarine flushing and for the dispersal of land-derived contaminants into the marine environment.

In order to establish seawater contamination by emerging protozoan parasites, we used qPCR to molecularly characterize and evaluate the parasitic burden of Giardia duodenalis, Cryptosporidium spp., Toxoplasma gondii, and Cyclospora cayetanensis in 1255 wild bivalve mollusks collected along the Tunisian coasts. T. gondii, G. duodenalis and C. cayetanensis were detected in 6.9% (99% CI=1.6–12.2%) pools of Ruditapes decussatus. None of the samples were found positive to Cryptosporidium spp.; 6.6% pools of R. decussatus were positive for T. gondii Type I, 1.6% for G. duodenalis assemblage A, and 1.6% for the association T. gondii Type I/C. cayetanensis/G. duodenalis assemblage A. R. decussatus harbored up to 77500 oocysts/sample of T. gondii, up to 395 cysts/sample of G. duodenalis, and 526 oocysts/sample of C. cayetanensis. These results provide the first evidence that the Tunisian coasts are contaminated by zoonotic protozoan parasites that can constitute a direct or indirect risk for human health.

The occurrence of the protozoan parasites Toxoplasma gondii and Cyclospora cayetanensis was molecularly investigated in the hemolymph, gills, stomach, hepatopancreas and gonads of the eleven invasive Atlantic blue crab Callinectes sapidus from the Lesina Lagoon (Mediterranean Sea). Out of 11 blue crabs, 6 (54.5%) and 4 (36.4%) were found positive to T. gondii and C. cayetanenis, respectively; parasites were found only in the six females analysed, while the remaining five males resulted negative. Moreover, out of 55 tissues samples, 7 (12.7%) and 8 (14.5%) were positive to T. gondii and C. cayetanensis, respectively with hemolymph and gills being the most infected tissues. This is the first report of the presence of protozoan pathogens in wild crab species collected from a Mediterranean lagoon. The present results may provide a baseline reference on microbial infection in the species for invaded Mediterranean waters, and on the potential health risks related with its consumption if eaten raw.

The present study aimed to evaluate the possible association between coronavirus disease 2019 (COVID-19) and latent Toxoplasma gondii infection in a group of patients and healthy individuals. Blood samples were obtained from 269 PCR-positive COVID-19 patients. The serum was separated and tested for the existence of anti-T. gondii antibodies (IgG) using a commercial enzyme-linked immunosorbent assay kit. The prevalence of latent toxoplasmosis between a subgroup of the patients (aged under 55 years old) and COVID-19 negative individuals was compared. Anti-T. gondii antibodies were found in 226/269 (84.0%) patients with COVID-19. Anti-Toxoplasma antibodies were detected in 72/91 (79.1%) cases and 96/123 (78.0%) COVID-19 negative individuals (odd ratio = 1.1; 95% confidence interval: 0.55–2.07, P = 0.85). The median and interquartile range (IQR) of the IgG titer were not statistically significant different between case (97.3 [31.0–133.5]) and control groups (34.4 [13.0–144.5]) (P = 0.10). These findings demonstrated that latent Toxoplasma infection is prevalent amongst the COVID-19 patients. It also did not find any significant association between chronic toxoplasmosis and COVID-19.

The parasites are repeatedly confronting their host to take advantage of nutrients for multiplication and survival. In this sense, a wide spectrum of molecules is released from both sides, with immune-regulatory activity, accompanying this biological battle. Such parasites and their valuable molecules can be directed toward microbial-based cancer therapy. Herein, we contrived a systematic review to gather information on the antitumor activity of parasite-derived compounds. Following systematic search in Web of Science, ScienceDirect, Scopus, PubMed, ProQuest and Embase until 31 December 2019, a total number of 51 articles (54 datasets) were finally included in this review. Thirteen parasitic agents were found to possess possible antitumor activity, comprising protozoan species Toxoplasma gondii, Trypanosoma cruzi, Trichomonas vaginalis, Acanthamoeba castellanii, Besnoitia jellisoni, Leishmania major, Plasmodium yoelii, and Plasmodium lophurae, as well as parasitic helminths Toxocara canis, Echinococcus granulosus, Taenia crassiceps, Trichinella spiralis, and Schistosoma mansoni. Most experiments were done based on antigenic preparations from T. gondii (16 studies), E. granulosus (10 studies), T. spiralis (8 studies), and T. cruzi (6 studies). Possible antitumor properties of the selected parasites were revealed in this review. However, precise molecular basis of anticancer activity for each parasite remains to be elucidated in the future.

Toxoplasmosis is a zoonotic disease caused by an obligatory intracellular parasite, Toxoplasma gondii. The congenital form of the disease is a significant health problem around the world. This study aimed to determine the incidence of congenital toxoplasmosis in the newborn of Shiraz, Southern Iran, between 2013 and 2018. A total of 2498 blood samples of neonates were randomly collected by a standard heel puncture technique and dried on Guthrie cards from Shiraz newborn screening center. We provided questionnaire forms for mothers according to their demographic characteristics, such as age, place of residence, history of having cats as pet, and literacy level. ELISA immunocapture and PCR assays were applied to detect anti-Toxoplasma IgM and the parasite DNA in dried blood spot samples. The anti-Toxoplasma IgM antibody was detected in two out of the 2498 infants. Moreover, borderline titers were observed in 3 samples, which were considered suspicious, so these were retested after 18 months to detect IgG against Toxoplasma. Positive IgG titer was observed in two infants who had a positive IgM level. The genome of Toxoplasma was detected in one sample out of 2498. No significant differences were seen between the epidemiological factors with congenital infection. The incidence of congenital toxoplasmosis is estimated at 0.08% of studied samples. It seems that this incidence could present to the health ministry as a logical research achievement for the national screening program of newborns in Iran.

Toxoplasma gondii, Cryptosporidium parvum, and Giardia duodenalis are human waterborne protozoa. These worldwide parasites had been detected in various watercourses as recreational, surface, drinking, river, and seawater. As of today, water protozoa detection was based on large water filtration and on sample concentration. Another tool like aquatic invertebrate parasitism could be used for sanitary and environmental biomonitoring. In fact, organisms like filter feeders could already filtrate and concentrate protozoa directly in their tissues in proportion to ambient concentration. So molluscan shellfish can be used as a bioindicator of protozoa contamination level in a site since they were sedentary. Nevertheless, only a few researches had focused on nonspecific parasitism like protozoa infection on aquatic invertebrates. Objectives of this review are twofold: Firstly, an overview of protozoa in worldwide water was presented. Secondly, current knowledge of protozoa parasitism on aquatic invertebrates was detailed and the lack of data of their biological impact was pointed out.

The ubiquitous protozoa Toxoplasma gondii is now the subject of renewed interest, due to the spread of oocysts via water causing waterborne outbreaks of toxoplasmosis in different parts of the world. This overview discusses the different methods for detection of Toxoplasma in drinking and environmental water. It includes a combination of conventional and molecular tools for effective oocyst recovery and detection in water sources as well as factors hindering the detection of this parasite and shedding light on a promising new molecular assay for the diagnosis of Toxoplasma in environmental samples. Hopefully, this attempt will facilitate future approaches for better recovery, concentration, and detection of Toxoplasma oocysts in environmental waters.

Water quality is a public health concern that calls for relevant biomonitoring programs. Molecular tools such as polymerase chain reaction (PCR) are progressively becoming more sensitive and more specific than conventional techniques to detect pathogens in environmental samples such as water and organisms. The zebra mussel (Dreissena polymorpha) has already been demonstrated to accumulate and concentrate various human waterborne pathogens. In this study, first, a spiking experiment to evaluate detection levels of Toxoplasma gondii DNA in zebra mussel organs using real-time PCR was conducted. Overall, lower DNA levels in the hemolymph, digestive gland, and remaining tissues (gonad and foot) were detected compared to mantle, muscle, and gills. Second, an in vivo experiment with 1000 T. gondii oocysts per mussel and per day for 21 consecutive days, followed by 14 days of depuration time in protozoa-free water was performed. T. gondii DNA was detected in all organs, but greatest concentrations were observed in hemolymph and mantle tissues compared to the others organs at the end of the depuration period. These results suggest that (i) the zebra mussel is a potential new tool for measuring T. gondii concentrations and (ii) real-time PCR is a suitable method for pathogen detection in complex matrices such as tissues.