Hematodinium perezi infections in adult arid juvenile blue crabs Callinectes sapidus from coastal bays of Maryland and Virginia, USA (original) (raw)
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Diseases of aquatic organisms, 2016
The dinoflagellate Hematodinium perezi is a prolific pathogen of the blue crab Callinectes sapidus along the Atlantic and Gulf of Mexico coasts of North America. High prevalence, sometimes approaching 100%, and outbreaks with high mortality are associated with higher salinities. H. perezi has not been reported previously in blue crabs from Louisiana, USA, where salinities in coastal habitats are generally below the parasite's favorable range. However, the possibility that H. perezi infects blue crabs in higher salinity habitats offshore has not been investigated. A PCR-based test for H. perezi was used to screen blue crabs collected from both high and low salinity areas. These included juvenile and adult crabs from inshore marshes where salinities are relatively low and from higher salinity offshore shoals that are spawning sites for females. H. perezi was detected in blue crabs from offshore shoals (prevalence = 5.6%) but not in juvenile or adult crabs from inshore habitats. Me...
2012
Hematodinium sp. infections are relatively common in some American blue crab (Callinectes sapidus) populations in estuaries of the western Atlantic Ocean. Outbreaks of disease caused by Hematodinium sp. can be extensive and can cause substantial mortalities in blue crab populations in high salinities. We examined several species of crustaceans to determine if the same species of Hematodinium that infects C. sapidus is found in other crustaceans from the same localities. Over a 2-yr period, 1,829 crustaceans were collected from the Delmarva Peninsula, Virginia, examined for the presence of infections. A portion of the first internal transcribed spacer (ITS1) region of the ribosomal RNA (rRNA) gene complex from Hematodinium sp. was amplified and sequences were compared among 35 individual crustaceans putatively infected with the parasite, as determined by microscopic examination, and 4 crustaceans putatively infected based only on PCR analysis. Of the 18 crustacean species examined, 5 were infected with Hematodinium sp. after microscopic examination and PCR analysis, including 3 new host records, and an additional species was positive only via PCR analysis. The ITS1 rRNA sequences of Hematodinium sp. from the infected crustaceans were highly similar to each other and to that reported from C. sapidus (.98%). The similarity among these ITS1 sequences and similarities in the histopathology of infected hosts is evidence that the same species of Hematodinium found in C. sapidus infects a broad range of crustaceans along the Delmarva Peninsula. Our data indicate that the species of Hematodinium found in blue crabs from estuaries along the east coast of North America is a host generalist, capable of infecting hosts in different families within the Order Decapoda. Additionally, evidence indicates that it may be capable of infecting crustaceans within the Order Amphipoda.
Diseases of Aquatic Organisms, 2009
Infection with the parasitic dinoflagellate Hematodinium sp. can be devastating to blue crab Callinectes sapidus populations. Morbidity and mortality appear to depend on the burden of parasitic organisms. Heavily infected crabs become lethargic and, if not preyed upon, succumb to overwhelming infection. We report on the transmission of Hematodinium sp. into blue crabs that were fed pieces of infected tissues and examined for evidence of infection at time periods from 1 to 48 h and for the general state of their health after 4 d. During the first 16 h after feeding, Hematodinium sp. was found in the gut, followed by large increases in hemolymph hemocytes and the appearance of hemocytic nodules in tissues. By 16 h, the hemocytic nodules appeared poorly circumscribed and disorganized. No nodules were seen in a heavily infected crab after 24 h. By the end of the 48 h after feeding, 73% (11 of 15) of the crabs had shown evidence of infection with Hematodinium sp. Those crabs with infection intensities (Hematodinium sp. as percent of cells in hemolymph) higher than 20% were dead within 4 d.
Evidence for a free-living life stage of the blue crab parasitic dinoflagelate, Hematodinium sp
Harmful Algae, 2006
Hematodinium sp. is a parasitic dinoflagellate reported to cause disease and death in a variety of crustacean species including the blue crab (Callinectes sapidus). However, because of difficulties in the culture of Hematodinium sp. associated with blue crabs, little is known about its life cycle or mode of transmission. Here, we report the first detection of this organism outside of a metazoan host and provide evidence that this life stage can act as an infective agent. Observations of dinospores in crab hemolymph samples suggest that dinospores may be responsible for waterborne disease transmission. Additionally, we developed and validated a quantitative Real Time PCR assay for the detection of Hematodinium sp. inside and outside of a host organism that will be useful for future investigations of Hematodinium biology and Hematodinium sp.-infection etiology. Based on the observations of a free-living form of Hematodinium sp. and the association of this parasite with a widespread epizootic in blue crab populations, we propose that Hematodinium sp. be considered a Harmful Algal Bloom species. # 2005 Published by Elsevier B.V.
Parasitology, 2014
SUMMARY This study reports on the prevalence and severity of infections caused by the parasitic dinoflagellate, Hematodinium in juvenile edible crabs (Cancer pagurus) found in 2 intertidal survey sites (Mumbles Head and Oxwich Bay) in the Bristol Channel, UK. Crabs were assessed for the presence and severity of Hematodinium infections by the histological examination of infected tissues. Such infections were found to exhibit a seasonal trend in the 2 study areas with high numbers of animals (ca. 30%) infected in the spring to summer but with low severity. Conversely, in November only ca. 10% of crabs were infected but these animals had large numbers of parasites in their haemolymph and other tissues. At this time, the carapace and underlying tissues of infected crabs had the chalky, pinkish-orange appearance that is characteristic of this disease. Hematodinium-infected crabs ranged in size from 12 to 74 mm carapace width. Overall, it is concluded that the high prevalence of infection...
PloS one, 2018
In the blue crab, Callinectes sapidus, early studies suggested a relationship between smaller crabs, which molt more frequently, and higher rates of infection by the dinoflagellate parasite, Hematodinium perezi. In order to better explore the influence of size and molting on infections, blue crabs were collected from the Maryland coastal bays and screened for the presence of H. perezi in hemolymph samples using a quantitative PCR assay. Molt stage was determined by a radioimmunoassay which measured ecdysteroid concentrations in blue crab hemolymph. Differences were seen in infection prevalence between size classes, with the medium size class (crabs 61 to 90 mm carapace width) and juvenile crabs (≤ 30 mm carapace width) having the highest infection prevalence at 47.2% and 46.7%, respectively. All size classes were susceptible to infection, although fall months favored disease acquisition by juveniles, whereas mid-sized animals (31-90 mm carapace width) acquired infection predominantl...
This study reports on an emerging fungal disease of the edible 21 crab, Cancer pagurus. Juvenile (pre-recruit) crabs were found to be subject to 22 this disease condition during the months of May to September at two intertidal 23 sites in South Wales, U.K. Histopathology revealed that the fungi overwhelm 24 the host response in the tissues, leading to progressive septicaemia. The 25 causative agent of this infection was isolated and grown in pure culture and 26 was identified as a member of the Ophiocordyceps clade by sequencing of the 27 small subunit of the fungal rDNA. Of the crabs naturally infected with the 28 fungus, 94% had a co-infection with the parasitic dinoflagellate, 29 Hematodinium. To determine if there was any interaction between the two 30 disease-causing agents, apparently fungus-free crabs, both with and without 31 natural Hematodinium infections, were challenged with the fungal isolate. The 32 presence of Hematodinium caused a significant reduction in fungal 33 multiplication in the hemocoel of the crabs in comparison to Hematodinium-34 free individuals. Histopathology of co-infected crabs showed a systemic 35 multiplication of Hematodinium within host tissues, leading to a rapid death; 36 whilst Hematodinium-free crabs experimentally infected with the fungal 37 isolate, died due to fungal sepsis (septicemia) with the same characteristic 38 pathology as seen in natural infections.