Nematode Parasites PDF

## Nematode Parasites ### Family | Genus | Species | Host | Habitat | Morphology | Eggs | Life Cycle | Pathogenesis | Diagnosis ------- | -------- | -------- | -------- | -------- | -------- | -------- | -------- | -------- | -------- Ascaridae | Ascaris | _A. suum_ | Pig | Small intestine | Large,...

## Nematode Parasites ### Family | Genus | Species | Host | Habitat | Morphology | Eggs | Life Cycle | Pathogenesis | Diagnosis ------- | -------- | -------- | -------- | -------- | -------- | -------- | -------- | -------- | -------- Ascaridae | Ascaris | _A. suum_ | Pig | Small intestine | Large, stout worms; males up to 25 cm with equal spicules, females up to 40 cm. Pinkish when fresh; mouth with 3 lips with club shaped esophagus. | Spherical, subspherical, or ovoid. 50-75 µm by 40-50 μm. Thick shell, dark greenish-brown. Outer albuminous layer mammillated (prominent projections). One-cell stage when fresh. | Direct life cycle. Eggs require 3-4 weeks to become infective. Hepato-pulmonary migration: L2 → liver → lungs → small intestine. Prepatent period: 6-8 weeks. | Larval migration causes "milk spots" in the liver and transient obstruction, pneumonia. Adults may cause malnutrition intestinal obstruction. | Fecal examination for eggs Ascaridae | Ascaris | _A. lumbricoides_ | Human | Small intestine | Similar to _A. suum_ but distinct species. No cross-infections between pigs and humans. | Almost spherical or subglobular. Up to 100 μm in diameter. Thick, coarsely pitted albuminous layer. | Direct life cycle. Eggs become infective in 10-14 days. Hepato-pulmonary migration. Prepatent period: 10-12 weeks. | Intestinal obstruction, colic, unthriftness, loss of weight, imbaction, perforation (may be fatal). Coughing with grayish nasal discharge. | Fecal examination for eggs Ascaridae | Parascaris | _P. equorum_ | Equine | Small intestine | Larger than Ascaris, rigid and has thick cuticle; males up to 28 cm, females up to 50 cm. Mouth with 3 lips and interlabia. | Subglobular to spherical. About 80 µm in size. Thick, deep brown, heavily pitted shell. | Complex life cycle: 4 modes of infection: 1. Ingestion of infective eggs (L2). 2. Prenatal infection (transplacental). 3. Transmammary infection (via milk). 4. Paratenic hosts (rodents, birds). Prepatent period: 3-5 weeks. | Larval migration causes pneumonia; adults cause enteritis, intestinal obstruction. Zoonotic: Visceral larva migrans in humans (e.g., ocular granuloma). | Fecal examination for eggs Ascaridae | Toxocara | _T. canis_ | Dog | Small intestine | Males up to 10 cm, females up to 18 cm. Cervical alae (lanceolate); tail of males has a finger-like process. | Subglobular. About 75 µm in size. Thick, pitted shell, almost colorless. | No prenatal infection. Transmammary and paratenic host infections occur. Prepatent period: 8 weeks. | Non-migratory; causes pot-belly, diarrhea. | Fecal examination for eggs Ascaridae | Toxocara | _T. cati_ | Cat | Small intestine | Similar to _T. canis_ but males up to 25 cm, females up to 40 cm. Thin, soft, transparent cuticle. | Subglobular. 75-95 µm by 60-75 μm. Thick, finely pitted albuminous layer. | Prenatal and transmammary infections are primary routes. Prepatent period: 3-4 weeks. | Emaciation, diarrhea, pneumonic signs in calves. | Fecal examination for eggs Ascaridae | Toxascaris | _T. vitulorum_ | Cattle | Small intestine | Stout, whitish worms; Similar to _T. canis_ but males up to 25 cm, females up to 40 cm. Thin, soft, transparent cuticle. Differentiated from Toxocara by absence of finger-like tail process in males. | Slightly ovoid. 85 µm by 75 µm. Smooth, thick shell. | Non-migratory; infection via eggs or paratenic hosts. Prepatent period: 11 weeks. | Less pathogenic than Toxocara. | Fecal examination for eggs Ascaridae | Toxascaris | _T. leonina_ | Dog & Cat | Small intestine | | | | | Ascaridae | Heterakis | _H. gallinarum_ | Poultry | Small intestine | Large, white worms; Mouth with 3 lips, esophagus without posterior bulb (club) with long cervical alae. Males up to 8 cm, equal or subequal spicules & narrow alae. Females up to 12 cm, vulva ant. to mid. Circular precoloacal sucker with thick rim. 10 pars of caudal papillae. | Distinctly oval unsegmented, Smooth & thick shell. One-cell stage when fresh. | Direct life cycle. Eggs become infective in 3 weeks, Non-migratory; develops in intestinal lumen. Prepatent: 5-8 weeks. | Catarrhal enteritis, intestinal obstruction. | Fecal examination for eggs Subuluridae | Subulura | _Subulura brumpti_ | Galliform birds | caeca | Small, whitish worms; Mouth with 3 lips; esophagus with posterior bulb & some distance cervical alae. males up to 1.3 cm, unequal spicules & wide alae. Females up to 1.6 cm, vulva behind mid. Large pedunculated precoloacal sucker. 12 pair. | Oval, Smooth shell. Difficult to distinguish from Ascaridia galli eggs. | Direct life cycle. Eggs or larvae in earthworms act as transport hosts, Non-migratory; develops in cecal lumen. Prepatent: 4 weeks. | Vector for Histomonas meleagridis (blackhead disease in turkeys). | Fecal examination for eggs Anisakidae | Anisakidae | _Anisakis, Porrocaecum, Contracaecum, Lagochilascaris_ | Marine mammals, birds, and accidentally humans | muscles | Small buccal capsule with three teeth & double bulb shaped esophagus. Males up to 1 cm, equal spicules & large alae. Females up to 1.4 cm, vulva ant. to mid. Eliliptical precoloacal sucker. 10 pairs. | Subglobular thin shelled larvated eggs (L1) 60-80 μm | Indirect. Eggs ingested by beetles/cockroaches, develop to L3, and infect birds when ingested | Inflammatory reactions in the caeca during heavy infections | Larvae in fish or crustaceans | Indirect. Humans infected by eating raw/undercooked fish | Clinical signs, serology, or endoscopy Oxyuroidea | Oxyuris | _Oxyuris equi_ | Horses, donkeys | Large intestine cecum | Pointed tails, ant. end has 3 lips & douple bulbed eosophagus. Females up to 10 cm males 1cm, caudal alae, pin like spicule. | Eggs oval (plano convex-D) with mucoid plug | Direct, non-migratory. Eggs containing L3 ingested. L4 feeds on mucosa, adults feed on intestinal content. | Anal pruritis (itching) due to egg-laying females, loss of hair. Intestinal erosions in heavy infections | Egg masses on perineal skin (scotch or adhesive tape teq.) adult worms in feces Oxyuroidea | Syphacia | _Syphacia muris, S. obvelata_ | Rodents (rats, mice) | Large intestine | Samller than _O. equi_ | Direct. Eggs ingested, have zoonotic importance | Mild intestinal irritation | Fecal examination for eggs Oxyuroidea | Skrjabinema | _Skrjabinema ovis_ | Sheep(rarely), goats | Large intestine | Up to 1 cm long | Direct. Eggs ingested | Rarely pathogenic | Necrospy findings Rhabditoidea | Strongyloides | _S. Westeri equines_ | Horses, donkeys | Small intestine (Avium caeca) | Very small hair-like worms with minute openings and twisted internal organs, only females are parasitic. Parasitic larvae and females has rhabditiform (4 molts) esophagus while dults have flariform one. | Eggs oval, thin, has L1 when laid (in herbivores) Hatching occurs in intestine (in carnivores). Can be parasitic (homogenic) or free-living (heterogenic), lung migration may occur. | L3 infects via skin penetration or ingestion (All), prenatal (pig). Transmamm. (pig, rum, equine). auto or hyper infection(man). Eggs can fertilize itself via (parthenogenesis) | Enteritis, diarrhea, erythrema, skin/lung reactions during larval migration and growth problems. | Fecal examination for eggs Rhabditoidea | Strongyloides | _S. Papillosus → rum S. Stercoralis → Man, dogs & cats. S. Ransomi → pig S. Avium → poultry_ | Ruminants | Small intestine (Avium caeca) | | | | | Rhabditoidea | Strongyloides | _S. Avium → poultry_ | Poultry | Small intestine (Avium caeca) | | | | | Spiruroidea | Spirocerca | _Spirocerca lupi_ | Dogs, occasionally cats | Upper digestive tract & eye | Pink, has two lips each is trilobed (M.O is hexagonal), coiled worms in esophageal nodules. Males up to 5.5 cm, prominent caudal alae, pre & post ananl paplillae, unequal spicules. females up to 8 cm, has blunt end, vulva located in esophageal region. | Thick shelled egg contaies larva. | Indirect. Eggs ingested by dung beetles (eaten by paratenic host), develop to L3, and infect dogs | Esophageal granulomas, aortic scarring, potential cancer | Fecal examination for larvae, duodenal aspirate. Spiruroidea | Habronema | _Habronema muscae, H. microstoma, H. megastoma_ | Horses, donkeys | Stomach | Small, slender worms. Males up to 2.2 cm (musca, micro) 1cm (mega), their tail has spiral coil. Females up to 3.5 cm (musca, micro) 1.3cm (mega), oviviviparous. | | Indirect: 1- Musca spp. → musca & mega 2- stomaxys calcitrans & lyperosia irritants → micro Eggs may hatch before being passed in feces, ingested by fly larvae, develop to L3, and infect horses | Gastric irritation, atrophy for glands, tumors, cutaneous "summer sores," conjunctivitis with nodular thickening, pulmonary habronemiasis. | Fecal examination for eggs, endoscopy, or radiography Spiruroidea | Parabronema | _Parabronema spp._ | Ruminants | abomasum | | | | | Thelazidae | Thelazia | _T. lacrymalis → equine T. Rhodesi → cattle T. Californiensis & callipaeda → dogs, cats, occasionally humans & sheep_ | Eye | Small, thin, white worms (1-2 cm)n cuticle has Resembles Haemonchus spp. But prominent striations at ant. end, No lips, male has 2 unequal spicules. | | Viviparous, indirect. L1 ingested by flies, develop to L3, and infect host via lachrymal secretions | Conjunctivitis, keratitis, corneal ulcers, corneal opacity in high manfestations. Rarely diagnosed | Observation of worms in conjunctival sac Filariidae | Parafilaria | _P. Bovicola → cattle P. Multipapillosa → equine_ | Under skin (intermuscular C.T) | Selender, white worms (3-6 cm), ant. end has many papillae & circular ridges. Male tail is short, blunt, has caudal alae, unequal dissimilar spicules & pre&post-coloacal papillae. Female tail is blunt, vulva is anteriorly near M.O | | Indirect: Musca spp. → bovicola Haematobia → multi - Eggs (ovoviviparous) or larvae (L1 microfilariae) ingested by flies from bleeding points, develop to L3, and infect host | Skin nodules, hemorrhagic exudates ("bleeding points") | Observation of hemorrhagic exudates or skin nodules Filariidae | Setaria | _Setaria equina, S. labiato-papillosa_ | Horses, cattle | Peritoneal cav., rarely in pleural cav. & erratic in CNS | Long, slender worms, has raised chitinous peri buccal ring & cephalic papillae. Males up to 8 cm, females up to 13 cm and has a screw like filamentous tail ended in a simple point (equina) or marked button (labiato-papillosa) | | Indirect. Mosquitoes as intermediate hosts, sheathed microfilaria develops to L3, injected to the animal via mosquito bite. Prepatent: 8-10m | Usually harmless, but may cause CNS migration in sheep/goats (lumbar paralysis) | Blood smears for microfilariae or spinal fluid examination Onchocercidae | Onchocerca | _O. reticulata (cervicalis) → equines ligaments O. Gibsoni & Gutturosa (lienalis) → cattle O. armillata → bovine aorta (unknown I.H)._ | Fibrous T, ligaments, intramuscular C.T | Slender worms (2-6 cm), coiled in tissue nodules | Indirect: Culicoides → riticulata & gibsoni Simulium → gutturosa Unshethed microfilariae in skin tissue spaces ingested by flies, develop to L3, and infect host | Subcutaneous nodules, "fistulous withers" in horses, aortic aneurism and often death | Skin biopsy for microfilariae Filariidae | Dirofilaria | _Dirofilaria immitis_ | Dogs, cats, rarely humans | Right heart side | Long, selender-like worms. Males up to 1.5cm, blunt spirally coiled post. End, lateral alae. Females up to 30cm with vulva located behind the end of the esophagus. | | Indirect. Mosquitoes as intermediate hosts (L3 I.S), microflariea is unsheathed with plunt ant. & tabered post. and tends to be periodical. | Canine heartworm disease, pulmonary hypertension, congestive heart failure and embolisms which lead to kidney & liver diseases. | Blood tests for microfilariae or antigen Trichuridae | Trichuris | _T. ovis → sheep & goat T. Globulosa → cattle T. Suis → pigs T. Vulpis → dog & fox T. Trichiura → man_ | Sheep, pigs, dogs, humans | Large intestine (cecum) | Whip-like, thick posterior, thin anterior has a spinen coloaca is terminal. Males are coiled and spiney up to 4 cm. Females up to 8 cm and slightly curved and digitiform, vulva is in the junction. The egg is characteristic lemon shaped with transparent mucoid plug at both ends, yellow or brown. | Direct. Eggs ingested, L1 penetrates cecal mucosa | Cecal inflammation, diarrhea in heavy infections, anemia, rectum prolapse in man. | Fecal examination for eggs Capillaridae | Capillaria (hair worm) | Wide range | Wide range | Large intestine (cecum) | Very thin, hair-like worms (1-5 cm), very long esophagus (cellular or trichoid) Males have long thin single spicule enclosed in a sheath resembles a bursa. Females contain eggs like trichus ones but colorless (65 by 35 micro) | Direct (egg containing L1 ingestion) or indirect (earthworms "containing L1" as intermediate hosts). In case of C. hepatica, eggs laid in liver and the infection occurs by predation. | Enteritis, respiratory issues, or liver damage, lowered growth, reduced egg production. | Fecal examination for eggs or necropsy findings Trichinellidae | Trichinella | _Trichinella spiralis_ | Pigs, humans, other mammals | Highly active muscles | Very small worms, adults have an anterior stylet the esophagus is nearly one third of its length. Males up to 1.5 mm, has No-spiculesn two lateral flaps around cloaca & Females up to 4 mm, viviparous, the uterus is located in the mid. and full of developing larvae | Indirect. Fertilized females burrow deeper between the intestinal villi, L1 migrates to lymphatic vessels, travelles via blood stream, then encapsulates in SK Mm, muscle ingestes by another host and the cycle is repeated. | Enteritis, myositis, systemic symptoms in humans, has zoonotic importance. | Muscle biopsy (trichinoscope) or serology ### Capillaria species of birds | Name | Habitat | Life cycle | |---|---|---| | _C. Contorta_ (syn. _C. annulata_) | Oesophagus and crop of chicken, turkeys, ducks and wild birds. | Indirect | | _C.obsignata_ (syn. _C. columbae_) | Upper small intestine of chicken, turkeys and pigeons. | Direct. | | _C. caudinflata_ | Small intestine of chickens and turkeys | Indirect | | _C. anatis_ (syn. _C. collaris_) | Cecum | Direct. | ### Capillaria species of mammals 1. _C. bovis_: S. intestine of cattle, sheep and goats. Direct life cycle. 2. _C. longipes_: Small intestine of sheep and goats. Direct life cycle. 3. _C.aerophila_: Trachea and bronchi of dogs, fox, cat and man. Direct life cycle. 4. _C. papillosa_: Urinary bladder of rat 5. _C.plica_: Urinary bladder and kidney of dogs, fox and rarely cat. Life cycle either direct or indirect. 6. _C. felis_: Urinary bladder of cat. 7. _C.hepatica_: Liver of mice, rat, rabbits rarely in dog, cat and man. This table describes various nematode species that have been identified as important parasites in different animal species. Note that information about the "Life Cycle" of several species is incomplete. This summary is generated using OCR technology and requires verification.