- Bacterial

- Viral

- Fungal

- Spirochetal

- Protozoal

- Helminth

 - Nematode (round worm)- 2mm-35cm round and slender nonsegmented body with collagenous epicuticle surrounding a coelomique cavity containing sexually reproductive organs and digestive tract.
 -- zoonotic north american Brugia
 -- enterobius vermicularis
 -- onchocerciasis
 -- lymphatic filariasis (Wuchereria bancorfti, Brugia malayi..)
 -- dirofilariasia conjunctivae infection
 -- dracontiasis
 -- cutaneous larva migrans (Ankylostoma caninum)

 - Cestode (tape worm)- cystic larva with noncollagenous absorptive tegument with brush border (gastrodermis). Scolices disposed as sucker plates.
 --Cysticercus

 - Trematode (fluke)- leafshaped nonsegmented worms with noncollagenous syncytial tegument showing specialisations(spines or tubercules, ventral sucker plates, primitive gut..)
 --Schistosoma
 --Fasciola

- Arthropod induced
 - arachnids
 - insects