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Introduction: Common  Intestinal infection caused by adult nematode Ascaris lumbricoides (Roundworm) Occurrence/Distribution: ·   Cosmopolitan (worldwide), More prevalent in Nepal, India China, Korea, Philippines and South Pacific Islands. ·  It is very common in Nepal, especially in those persons with poor hygienic habits. ·   Children are more susceptible to ascariasis because they play in the contaminated soil and likely to have it without washing their hands. ·  It is the most common worm in Hostel students and children. ·   1/6th of the total population is estimated to be infected with Ascariasis. Causative organism: ·  Ascaris lumbricoides, show sexual dimorphism. ·  Male size: up to 20 cm (length), 2-4 mm (diameter), curved tail, shorter. ·  Female size: 20-40 cm (length), 4-6 mm (diameter), straight tail, longer. ·   Helminth parasite Ascaris lumbricoides that lives in the jejunum of the small intestine. ·  After copul...

· Endoparasite of the large intestine (ileocaecal region), caecum, colon, and vermiform appendix, especially in children (only in humans). Adhering to the mucosa, the worms feed on bacteria and epithelial cells. · Sexes are separate with distinct sexual dimorphism . Single penial seta is present in males. · Simple and monogenetic life cycle, females migrate out through the colon and rectum and deposit an enormous number of eggs in the skin folds of the anus and cause intense itching. When skin about the anus is scratched, eggs are picked upon fingers and under nails from where they find their way to food and are swallowed. They hatch in  the  stomach and the juveniles migrate to the colon and develop into adult worms. The life cycle completes in 2-4 weeks. · Infection occurs through contaminated food and water. Auto infection occurs by scratching (itching), Retroinfection (entry of larva or adult to the rectum or anti direction  of the digestive tr...

· Most dangerous roundworm as maximum people is infected by Ancylostoma. · Sexes are separate. · No secondary host, humans are the hosts. · They differ from roundworms like Ascaris having copulatory bursa. · Monogenetic, found in the small intestine of the human and feed upon tissues and blood (Sanguivorous) · The anterior end is curved. Its tip has a large buccal capsule with two pairs of sharp lancets for tearing intestinal mucosa in order to feed over it. The posterior end of the female is tapering and contains a caudal spine. In males, it is straight, broad, and bears a copulatory bursa. · Adults mate in the host’s intestine. Fertilized eggs pass out with the host’s faeces. Under favourable environmental conditions, the embryo of hookworm develops into the 1st stage juvenile or rhabditiform larva which hatches out within 1 or 2 days. It moults twice to form a 3rd stage filariform larva. It infects man by chan...

· Wucherer (1866 AD) reported larva of Wuchereria (microfilaria) in urine and Bancroft discovered adult females in 1876 AD. ·   Manson discovered that Wuchereria bancrofti requires transmission through the skin by a blood-sucking intermediate host. · Endoparasite living in  blood and lymph of man · Digenetic parasite , primary (final) host-man , secondary (intermediate) host and vector- mosquito (female Culex pipiens ) · Adult worms live coiled up in lymph vessels and lymph glands of man where they often block the flow of lymph. · Sexual dimorphism , female is larger and ovoviviparous or viviparous. It produces microfilariae. During the night, the microfilariae migrate to peripheral blood vessels. From here they are picked up by mosquitoes and spread to other humans. In humans, the adult parasite causes blocking of lymph glands and vessels resulting in Lymphoedema. This leads to enlargement of affected organs like leg, scrotum, mamm...

  · Intestinal endoparasite of man in the small intestine (especially in the jejunum) and some other vertebrates like pigs, cattle, etc, more prevalent in children than in adults as they are more susceptible to infection. · Body is cylindrical, unsegmented, elongated with tapering ends, anterior end is more slender than the posterior end. · Distinct sexual dimorphism i.e. sexes are separate. · Sanguivorous (Bloodsucking) · The worm is ammonotelic and ureotelic. Male size- up to 20 cm (length), 2-4 mm (diameter), smaller, curved tail, a pair of penial setae Female size - 20-40 cm (length), 4-6 mm (diameter), longer, straight tail, anus and gonopore · In males, Fifty pairs of pre-anal papillae are present in front of the cloaca and Five pairs of post-anal papillae behind the cloaca · Mouth is bounded by three broad lips (triradiate). One dorsal and two ventral-laterals. The dorsal lip bears two double papillae, one on each side. Each latero-ventral lip bears one double papilla and ...

Gegenbaur (1859 A.D.) created Nemathelminthes and Grobben (1910 A.D.) introduced aschelminthes . It includes about 15,000 species. VVI Examples of Phylum Nemathelminthes for Entrance Exams:- Ascaris lumbricoides (Roundworm) Ancyclostoma duodenale (Old World Hookworm) Necator americana (New World Hookworm) Loa loa ( Eye worm) Trichuris (Whipworm) Enterobius vermicularis  (Pin Worm or Threadworm or Churna) Wuchereria bancrofti (Filarial worm) Dracunculus (Guinea worm) Trichinella General characters of Nemathelminthes 1. Pseudocoelomate (Blastocoelomate) i.e. the body cavity is not lined by embryonic mesoderm and false coelom derived from embryonic Blastocoel. 2. Cylindrical and Bilaterally symmetrical i.e. body can be equally divided into two parts, has the syncytial epidermis . Epidermal cells lack cilia. The body is circular in cross-sections so-called roundworms. 3. Triploblastic i.e. three germ layers; ectoderm, mesoderm, and endoderm. 4. ...