Slideshow Worlds worst parasitic worms

Hookworms, roundworms, and other species of parasitic worms known as helminths have thrived in mammals for millions of years. Despite modern strides in sanitation, helminth infections still have a devastating impact on human health and well-being, especially in developing regions. This week, Science features two research papers that explore how parasitic infections can compromise the immune system by reawakening latent viruses and impeding antiviral defenses.The worms in this slideshow are responsible for some of the nastiest helminth infections in the world and cause a global burden of disease that outweighs better-known infections such as malaria and tuberculosis. For more, see this week’s issue of Science.*Correction, 1 August, 11:58 a.m.: Due to a mislabeled image from the photo’s source, Taenia solium was originally misidentified as Taenia saginata. Additionally, the photo of a cat tapeworm misidentified as Ancylostoma braziliense has been removed. Dirofilaria immitis. The “heartworm” is a type of roundworm that spreads through mosquito bites. Heartworms primarily infect dogs, but can also parasitize other animals such as cats and ferrets. Heartworms rarely infect humans. Necator americanus. Often called the “New World” hookworm, Necator americanus attaches itself to the villi of the small intestine to feast on a host’s blood, causing abdominal pain, diarrhea, and weight loss. Toxocara canis. Called the “dog roundworm,” Toxocara canis primarily infects dogs and other canids. Fully grown, these worms measure anywhere from 9 to 18 cm. Tapeworms. Tapeworms use hooks and suckers at the tip of the head to anchor themselves to a host’s intestinal lining. Ascaris lumbricoides. The female Ascaris lumbricoides lays up to 200,000 eggs per day. CDC estimates 807 to 1221 million people are infected with Ascaris worldwide. ‹› David Mack/Science Source Eye of Science/Science Source David Scharf/Science Source David Scharf/Science Source Ron Boardman/Life Science Image/FLPA/ Science Source Eye of Science/Science Source Eye of Science/Science Source Slideshow: World’s worst parasitic worms David Scharf/Science Source Ascaris lumbricoides. The female Ascaris lumbricoides lays up to 200,000 eggs per day. CDC estimates 807 to 1221 million people are infected with Ascaris worldwide. Necator americanus. Often called the “New World” hookworm, Necator americanus attaches itself to the villi of the small intestine to feast on a host’s blood, causing abdominal pain, diarrhea, and weight loss. Taenia solium. The pork tapeworm. Though intestinal infection is generally asymptomatic, T. solium larvae can cause cysticercosis in the brain, muscles, and other body tissue. T. solium is a major cause of adult seizures in dev Schistosoma mansoni. The “blood fluke” causes schistosomiasis, the world’s second most devastating parasitic disease. Schistosomiasis does not exist in the United States, but is common in children in developing nations. By Hassan DuRantJul. 31, 2014 , 3:00 PM Eye of Science/Science Source read more