Schistosomiasis vaccine
Encyclopedia
A Schistosomiasis vaccine is a vaccine against Schistosomiasis
Schistosomiasis
Schistosomiasis is a parasitic disease caused by several species of trematodes , a parasitic worm of the genus Schistosoma. Snails often act as an intermediary agent for the infectious diseases until a new human host is found...

 (also known as bilharzia, bilharziosis or snail fever), a parasitic disease
Parasitic disease
A parasitic disease is an infectious disease caused or transmitted by a parasite. Many parasites do not cause diseases. Parasitic diseases can affect practically all living organisms, including plants and mammals...

 caused by several species of fluke
Trematoda
Trematoda is a class within the phylum Platyhelminthes that contains two groups of parasitic flatworms, commonly referred to as "flukes".-Taxonomy and biodiversity:...

 of the genus Schistosoma
Schistosoma
A genus of trematodes, Schistosoma, commonly known as blood-flukes and bilharzia, includes flatworms which are responsible for a highly significant parasitic infection of humans by causing the disease schistosomiasis, and are considered by the World Health Organization as the second most...

. Schistosomiasis affects over 200 million people worldwide, mainly in rural agricultural and peri-urban areas of developing countries, and approximately 10% suffer severe health complications from the infection. While chemotherepeutic drugs, such as praziquantel
Praziquantel
Praziquantel is an anthelmintic effective against flatworms. Praziquantel is not licensed for use in humans in the UK; it is, however, available as a veterinary anthelmintic, and is available for use in humans on a named-patient basis....

, oxamniquine
Oxamniquine
Oxamniquine is an anthelmintic with schistosomicidal activity against Schistosoma mansoni, but not against other Schistosoma spp. Oxamniquine is a potent single-dose agent for treatment of S...

 and metrifonate
Metrifonate
Metrifonate or trichlorfon is an irreversible organophosphate acetylcholinesterase inhibitor.it is a prodrug which is activated non-enzymatically into 2,2-dichlorovinyl dimethyl phosphate ....

, are currently considered safe and effective for the treatment of schistosomiasis, reinfection occurs frequently following drug treatment, thus a vaccine is sought to provide long-term treatment. Several studies have determined that an age-dependent resistance to reinfection after cure of schistosomiasis through chemotherapeutic treatment occurs in some patients, suggesting that immunity
Immunity (medical)
Immunity is a biological term that describes a state of having sufficient biological defenses to avoid infection, disease, or other unwanted biological invasion. Immunity involves both specific and non-specific components. The non-specific components act either as barriers or as eliminators of wide...

 to Schistosoma
Schistosoma
A genus of trematodes, Schistosoma, commonly known as blood-flukes and bilharzia, includes flatworms which are responsible for a highly significant parasitic infection of humans by causing the disease schistosomiasis, and are considered by the World Health Organization as the second most...

infection can be acquired and vaccination may be an effective treatment option. Additionally, experimental vaccination efforts have been successful in animal model
Animal model
An animal model is a living, non-human animal used during the research and investigation of human disease, for the purpose of better understanding the disease without the added risk of causing harm to an actual human being during the process...

s of schistosomiasis.

Paramyosin has been proposed as a vaccine candidate.

Calpain
Calpain
A calpain is a protein belonging to the family of calcium-dependent, non-lysosomal cysteine proteases expressed ubiquitously in mammals and many other organisms. Calpains constitute the C2 family of protease clan CA in the MEROPS database...

 has been proposed in the past, but has been found to be less immunogenic.

Another target is Sm14.

Research support

Schistosomiasis has been considered a "neglected disease
Neglected Diseases
The neglected diseases are a group of tropical infections which are especially endemic in low-income populations in developing regions of Africa, Asia, and the Americas. Different organizations define the set of diseases differently...

" that disproportionately affects poorer localities and has received little attention from pharmaceutical companies. Support for current research efforts to develop hookworm vaccines has come from the Schistosomiasis Vaccine Initiative, a program of the Sabin Vaccine Institute
Sabin Vaccine Institute
The Sabin Vaccine Institute is a non-profit, 501 organization dedicated to reducing needless humansuffering from vaccine preventable and neglected tropical diseases through prevention and treatment...

 in collaboration with George Washington University
George Washington University
The George Washington University is a private, coeducational comprehensive university located in Washington, D.C. in the United States...

, the Oswaldo Cruz Foundation, the Chinese Institute of Parasitic Diseases, the Queensland Institute of Medical Research
Queensland Institute of Medical Research
The Queensland Institute of Medical Research is one of Australia’s largest medical research institutes, and is recognised worldwide for the quality of its research. QIMR was established in 1945 by an Act of the Government of Queensland. The original purpose of the Institute was to further the...

, and the London School of Hygiene and Tropical Medicine.

External links

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