Schistosomas are helminthic parasites more commonly known as blood flukes. At maturity they live in the intestinal blood vessels of humans, where copulation occurs with the female sitting in the groove of the male to receive sperm for fertilization. A gravid female then migrates to vessels of the rectum to lay her eggs, which are passed through the feces and into the external environment. The eggs hatch, and larva burrow into the tissue of their intermediate host: snails. They undergo successive generations of maturation, forming sporocysts in the snail, then become free swimming cercariae larva that penetrate the definitive host (humans) to reach sexual maturity and continue the cycle. These parasites are common in eastern Asia where rice is the dominate agricultural product. Rice farms are perfect environments for blood flukes because both definitive and intermediate hosts are present in the aquatic environment necessary for the developmental stages of the larva.
The world’s most detailed 3D model of the human papilloma virus (HPV) is the latest addition to Visual Science’s ongoing Viral Park project:
Papillomaviruses are a very diverse group of viruses that infect human skin and mucosal cells, which serve as a barrier between the environment and a human being. Most representatives of this group do not cause any symptoms, but [some strains can cause skin warts, and] highly pathogenic types may cause cancer.
A growing interest in HPV research can be partially — if not wholly — attributed to discovery of the relationship between HPV and cancer and the subsequent Nobel Prize in Physiology or Medicine (2008) awarded for this work. German scientist Harald zur Hausen has shown that nearly all cases of cervical cancer are the result of HPV infection. Vaccines against HPV are currently being actively developed and introduced, and the main targets for such vaccines include the most dangerous and common HPV types: HPV6, HPV11, HPV16, HPV18.
Credits: Ivan Konstantinov, Yury Stefanov, Alex Kovalevsky, Dmitry Shcherbinin, Anastasya Bakulina, Kirill Grishanin and Amy Gordon at the Visual Science company.
A breast cancer cell seen through an electron microscope (colorized)