A study on cercarial dermatitis in Khuzestan province, south western Iran

BACKGROUND: Cercarial dermatitis' or swimmer's itch' is an itchy inflammatory response to the penetration of the skin by non-human schistosome parasites. In the hot season, (May to September) in Khuzestan province in the south west of Iran, swimming in canals and agriculture activities in swampy areas are common. This survey was made on people from villages north of Ahwaz city in south west Iran, to estimate cercarial dermatitis in this region. METHODS: 2000 people were observed for clinical signs of cercarial dermatitis. Also 2000 Lymnaea gedrosiana snails were collected from agriculture canals and examined for animal schistosome cercariae during 1998–2000. RESULTS: From this survey 1.1% of people had pruritic maculopapular rash on their feet, hands or other parts of body. From the total of examined snails, 2.4% were found to be infected with bird schistosome cercariae including Trichobilharzia species. CONCLUSION: Cercarial dermatitis could be a health problem in this area. This is the first report of cercarial dermatitis from this region of Iran

Proteomic analysis of skin invasion by blood fluke larvae.

BackgroundDuring invasion of human skin by schistosome blood fluke larvae (cercariae), a multicellular organism breaches the epidermis, basement membrane, and dermal barriers of skin. To better understand the pathobiology of this initial event in schistosome infection, a proteome analysis of human skin was carried out following invasion by cercariae of Schistosoma mansoni.Methodology and resultsHuman skin samples were exposed to cercariae for one-half hour to two hours. Controls were exposed to water used to collect cercariae in an identical manner, and punctured to simulate cercarial tunnels. Fluid from both control and experimental samples was analyzed by LC/MS/MS using a linear ion trap in "triple play" mode. The coexistence of proteins released by cercariae and host skin proteins from epidermis and basement membrane confirmed that cercarial tunnels in skin were sampled. Among the abundant proteins secreted by cercariae was the cercarial protease that has been implicated in degradation of host proteins, secreted proteins proposed to mediate immune invasion by larvae, and proteins implicated in protection of parasites against oxidative stress. Components of the schistosome surface tegument, previously identified with immune serum, were also released. Both lysis and apoptosis of epidermal cells took place during cercarial invasion of the epidermis. Components of lysed epidermal cells, including desmosome proteins which link cells in the stratum granulosum and stratum spinosum, were identified. While macrophage-derived proteins were present, no mast cell or lymphocyte cytokines were identified. There were, however, abundant immunoglobulins, complement factors, and serine protease inhibitors in skin. Control skin samples incubated with water for the same period as experimental samples ensured that invasion-related proteins and host protein fragments were not due to nonspecific degeneration of the skin samples.ConclusionsThis analysis identified secreted proteins from invasive larvae that are released during invasion of human skin. Analysis of specific host proteins in skin invaded by cercariae served to highlight both the histolytic events facilitating cercarial invasion, and the host defenses that attempt to arrest or retard invasion. Proteins abundant in psoriatic skin or UV and heat-stressed skin were not abundant in skin invaded by cercariae, suggesting that results did not reflect general stress in the surgically removed skin specimen. Abundant immunoglobulins, complement factors, and serine protease inhibitors in skin form a biochemical barrier that complements the structural barrier of the epidermis, basement membrane, and dermis. The fragmentation of some of these host proteins suggests that breaching of host defenses by cercariae includes specific degradation of immunoglobulins and complement, and either degradation of, or overwhelming the host protease inhibitor repertoire

Human Schistosome Infection and Allergic Sensitisation

Several field studies have reported an inverse relationship between the prevalence of helminth infections and that of allergic sensitisation/atopy. Recent studies show that immune responses induced by helminth parasites are, to an extent, comparable to allergic sensitisation. However, helminth products induce regulatory responses capable of inhibiting not only antiparasite immune responses, but also allergic sensitisation. The relative effects of this immunomodulation on the development of protective schistosome-specific responses in humans has yet to be demonstrated at population level, and the clinical significance of immunomodulation of allergic disease is still controversial. Nonetheless, similarities in immune responses against helminths and allergens pose interesting mechanistic and evolutionary questions. This paper examines the epidemiology, biology and immunology of allergic sensitisation/atopy, and schistosome infection in human populations

Schistosome Dermatitis at Basswood Lake, Minnesota

During the summer of 1965 cases of schistosome dermatitis were reported at the Associated Colleges of the Midwest Wilderness Field, Station on Basswood Lake, Minnesota. Collection and isolation of gastropods from the lake revealed an extremely high incidence of Trichobilharzia ocellata infections in Lymnaea stagnalis. A flock of semi-domestic mallard ducks first introduced al the lake in 1963 are believed to be the principal definitive hosts contributing to the epidemiology of the parasite in the area

Cercarial Dermatitis Transmitted by Exotic Marine Snail

TOC summary: Introduction of exotic hosts can support unexpected emergence of unknown parasites

Indian Schistosomes: A Need for Further Investigations

India is uniquely positioned with regard to schistosomes and schistosomiasis—discovering seven new mammalian species with the existence of three more schistosome species: Orientobilharzia turkestanicum, O. harinasutai, and Schistosoma haematobium(?). An endemic focus of urinary schistosomiasis was reported from Gimvi village of Ratnagiri, Maharashtra with infrequent occurrence of schistosome eggs in human stools. Cercarial dermatitis has been reported to be more abundant in rural population using ponds, tanks, and so forth, for their domestic purposes. Few dermatitis cases were tested positive by CHR. Schistosome antigen was also detected in urine of five cases suggesting existence of active schistosomiasis in India. Nevertheless, human kind does not appear to be the usual host for Indian schistosomes in contrast to S. haematobium, S. mansoni, or S. japonicum. Various reasons for this phenomenon are discussed including evolution of Indian schistosomes, immune mechanisms, and environmental conditions. These and other aspects such as seasonal effect on the prevalence, snail infectivity, heterologous mating, existence of hybrids, and number of schistosomes in heterologous infections need further investigations with application of molecular techniques. Joint efforts by the national as well as international scientific community would be much more rewarding for better understanding of the parasite and the infection

Studies on Schistosome Dermatitis (\u27Swimmer\u27s Itch ) in Minnesota

A preliminary study was conducted to determine the causative agents of schistosome dermatitis ( swimmer\u27s itch ) in Minnesota and to determine the incidence schistosome infection in vector snails. A total of 1180 snails were collected from ten different localities, eight of which were sites of known schistosome activity . The incidence of schistosome infection in snails from individual areas was always less than 10 percent. Cercariae of Trichobilharzia ocellata from Lymnaea stagnalis were the most frequently-found schistosomes in our study

Reconnaissance of the Distribution and Abundance of Schistosomatium Douthitti, a Possible Human Disease Agent in Surface Waters in Alaska

Studies during the summer and early fall of 1967 show that Schistosomatium douthitti, a blood fluke which may pose a health hazard to man, is well established in the surface waters and surrounding terrestrial environments in the Fairbanks area. It is almost certain that this situation exists throughout Interior Alaska. Ecologically and geologically, the lakes and ponds in which it has been found are the most abundant types in the Interior and both the specific lakes and the types which they represent are abundantly used by man. The life cycle of the worm in this area is probably sustained mostly in small mammals, especially in Microtus pennsvlvanicus but also in Clethrionomys rutilus. The infection certainly over-winters in the mammal host but probably also survives in the snail host under the ice. Although the fluke was only found in two of the nine mammalian species examined, it is probable that it occurs in other than Microtus pennsvlvanicus and Clethrionomys rutilus.The work upon which this report is based was supported in part by funds provided by the U. S. Department of the Interior, Office of Water Resources Research, as authorized under the Water Resources Research Act of 1964. Project Number: A-O20- ALAS Agreement Number: 14-01-0001-89

Effect of Feedlots on Water Quality

The effect of feedlot runoff on water quality was examined. Samples were collected from river feedlots and offshore from lake feedlots and compared with samples from appropriate control sites. Bacterial contamination, as measured by the total coliform test over two successive summers, exhibited significant variation between feedlot and control sites. Coliform levels at lake sites adjacent to feedlots were double the levels at control sites; while in river systems average coliform levels downstream from feedlots were approximately 17 times the upstream controls