Tuesday 4 May 2004
There are 5 principal species that infect man which can be classified by the appearance of the egg:
Eggs w/ terminal spine: Schistosoma haemotobium, Schistosoma intercalatum
Eggs w/ lateral spine: Schistosoma mansoni
Round/ovoid, minutely spined: Schistosoma japonicum, Schistosoma mekongi
They are members of the group of worms called flukes. However, the schistosomes have the following differences:
Sexes are separate
Cylindrical in shape
Male: short and stumpy with copulatory groove.
Female: long and slender
Only one intermediate host
There is not a vaccine or any other prophylaxis available for prevention of schistosomiasis. Prevention is by avoiding fresh water. According to the CDC, because there is no practical way for the traveler to distinguish infested from noninfested water, travelers should be advised to avoid wading, swimming or other contact with freshwater in disease-endemic countries.
Schistosoma sp. are infectious agents of schistosomiasis. Schistosomiasis is a complex of acute and chronic diseases caused by worms belonging to the genus Schistosoma, or blood flukes, which live in the blood vessels of humans and other animals.
It is the most important helminth infection on the globe infecting 200 million in approximately 75 countries, second only to malaria in terms of socioeconomic & public health importance
It is frequently a “man-made” disease as it is associated with the development of irrigation systems and hydroelectric dams in third world countries.
People become infected by exposure to contaminated fresh water. This water gets contaminated by infected people working in the rice field, fisherman in the lake or children playing who indiscriminately defecate or urinate in the water.
Hu W, Brindley PJ, McManus DP, Feng Z, Han ZG. Schistosome transcriptomes: new insights into the parasite and schistosomiasis. Trends Mol Med. 2004 May 1;10(5):217-225. PMID: 15121048
Ross AG, Bartley PB, Sleigh AC, Olds GR, Li Y, Williams GM, McManus DP. Schistosomiasis. N Engl J Med. 2002 Apr 18;346(16):1212-20. PMID: 11961151