Centers for Disease Control/Division of Parasitic Diseases and Malaria
EOL staff
Life cycle of the Human Pinworm (Enterobius vermicularis and V. gregorii)Human pinworm eggs are deposited on the human host's perianal folds (1). Self-infection occurs by transferring infective eggs to the mouth with hands that have scratched the perianal area (2). Person-to-person transmission can also occur through handling of contaminated clothes or bed linens. Enterobiasis (pinworm infection) may also be acquired from surfaces in the environment that are contaminated with pinworm eggs (e.g., curtains, carpeting). A small number of eggs may become airborne and inhaled. These would be swallowed and follow the same development as ingested eggs. Following ingestion of infective eggs, the larvae hatch in the small intestine (3) and the adults establish themselves in the colon (4). The time interval from ingestion of infective eggs to oviposition by the adult females is about one month. The life span of the adults is about two months. Gravid females migrate nocturnally outside the anus and oviposit while crawling on the skin of the perianal area (5). The larvae contained inside the eggs develop (and the eggs become infective) in 4 to 6 hours under optimal conditions (1). Retroinfection, or the migration of newly hatched larvae from the anal skin back into the rectum, may occur but the frequency with which this happens is unknown.From Centers for Disease Control Parasites and Health website.
Figure 1.Photomicrographs of Xiphinema elongatum and Xiphinema pachtaicum. A, C, D, H Body habitus, head region, entire female reproductive part, tail region of Xiphinema elongatum respectively B, E, F, G Body habitus, head region; female reproductive part and tail part of Xiphinema pachtaicum respectively. A = 250 µm; B = 100 µm; D, F = 50 µm; C, E, G, H = 25 µm
Genus Monhystera body is mostly tapering considerably posteriorly. Caudal sucker small, somewhat pointed. Setae very few. Pharyngeal cavity none. Oesophagus uniform. Spicules long and narrow. Ocellus single, often absent.
A. Steven Munson, USDA Forest Service, Bugwood.org
Wikimedia Commons
Summary[edit] Description: English: Bursaphelenchus xylophilus, pine wilt nematode, USA. Male with spicule visible. Date: 20 September 2013, 20:49:21. Source: : This image is Image Number 1470131 at Forestry Images, a source for forest health, natural resources and silviculture images operated by The Bugwood Network at the University of Georgia and the USDA Forest Service.. Author: A. Steven Munson, USDA Forest Service, Bugwood.org.
Summary[edit] Description: Polski: Mikrofilaria Loa loa. English: Loa loa - microfilaria. Date: 13 December 2011, 12:09:09. Source: Own work. Author: Stefan Walkowski.
Summary[edit] Description: English: Nematode pathogen transmitted by insect to domestic animals. Date: 2 September 2013, 14:40:17. Source: Own work. Author: Alan R Walker.
Summary[edit] Description: A feline roundworm (Toxocara cati) egg. Photo taken through a microscope at 400x. Date: 29 July 2006 (cropped on 2006-07-31). Source: Own work. Author: Joel Mills.
Summary[edit] Description: A canine roundworm (Toxascaris leonina) egg. Photo taken through a microscope at 400x. Date: 29 July 2006 (cropped on 2006-07-31). Source: Own work. Author: Joel Mills.
Summary[edit] Description: English: Dracunculus medinensis larvae. Parasite. Date: 1973. Source: : This media comes from the Centers for Disease Control and Prevention's Public Health Image Library (PHIL), with identification number #663. Note: Not all PHIL images are public domain; be sure to check copyright status and credit authors and content providers. العربية | Deutsch | English | македонски | slovenščina | +/−. Author: Photo Credit: Content Providers(s): CDC/Dr. Mae Melvin. Permission(Reusing this file): PD-USGov-HHS-CDC English: None - This image is in the public domain and thus free of any copyright restrictions. As a matter of courtesy we request that the content provider be credited and notified in any public or private usage of this image.