large to jumbo chicken eggs from at-risk fowl. Epidemiology Ascaris eggs can remain infective for years in the soil, even in a temperate climate. The migration of A. suum larvae through the lungs may cause secondary bacterial infections and result in acute respiratory symptoms in pigs. Morphology Males are about long, and wide. The posterior end is curved toward the ventral side with a pointed tail. They have simple spicules that measure long. Females are larger than males, measuring long and in diameter. From the anterior end, the vulva occupies about one-third of the body length. In addition to their large size, these species also have the three prominent lips. Each lip contains a dentigerous ridge, and no interlabia or alae. Females can lay up to 200,000 eggs per day, and their uteri can contain up to 27 million eggs at a time. Fertilized eggs are ovoid, ranging from 45 to 75 µm length and 35 to 50 µm in diameter. The uterine wall contributes to the lumpy and thick outer layer of the egg. The mammillated layer is stained golden-brown by the host's bile when the eggs are passed in faeces. Females can also deposit unfertilized eggs that are narrower and longer than normal fertilized eggs, ranging from 88 to 94 µm in length, and 44 µm diameter. Only the proteinaceous layer can be seen in unfertilized eggs, because after fertilization, the vitelline, chitinous, and lipid layers form. Incidents and outbreaks In Canada in 1970, a postgraduate student tainted his roommates' food with A. suum. Four of the victims became seriously ill; two of these suffered acute respiratory failure. Genetics A 273-megabase draft genome for A. suum was published in 2011. References Ascaridida Parasitic nematodes of mammals Swine diseases Veterinary helminthology Nematodes described in 1782 Taxa named by Johann August Ephraim Goeze