Parasitology-Lec 7 Lung Flukes

PARASITOLOGY LECTURE 7 – Flukes (Lungs and Intestines) Notes from Belizario,V.Y, Malte,B.I., Tiu,W.U. USTMED ’07 Sec C – AsM

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Miracidium develops from eggs w/in 2 to 7 weeks it pushes the operculum and swims in search of an appropriate snail host - 1st intermediate host: Antemelania asperata and Antemelania dactylus

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Sporocyst and Redia inside the snail the miracidium passes through one sporocyst and 2 redial stages

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Cercaria - cercariae emerge from the snail to seek a 2nd intermediate host - 2nd intermediate host: mountain crab (Sundathelphusa philippina)

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Metacercaria The cercaria penetrates the soft parts of the crustacean and encysts as a metacercaria in the gills, body muscles and viscera or legs crab may also be infected by eating infected snails - Infective stage: metacercaria - Definitive host: Man Adolescent worm following ingestion, the metacercaria excysts in the duodenum it traverses the intestinal wall, into the peritoneal cavity where it wanders and embeds itself in the abdominal wall for several days - parasite returns to the coelom, migrates throught the diaphragm to the pleural cavity where it penetrates the lungs and develops into adulthood

PARAGONIMUS WESTERMANI (Oriental Lung Fluke)

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main species that causes human paragonimiasis in the Philippines (P.philippinenesis and P.siamensis [cats] also cause this disease) patients often complain of cough and hemoptysis, clinical manifestation consistent with pulmonary tuberculosis (PTB); patients with this parasitic infection are often misdiagnosed with PTB

DISEASE

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Paragonimiasis (lung fluke disease, or pulmonary distomiasis or endemic hemoptysis or parasitic hemoptysis)

MORPHOLOGY

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Adult Color: reddish brown - Dimensions: 7-12mm x 4-6mm x 3.5-5mm (lwt) Shape: resembles coffee bean; round anteriorly, tapers posteriorly Integument: covered with single spaced spines Reproductive organs: o 2 lobed testes opposite each other midway between ventral sucker and posterior border o ovary anterior to testes and posterior to ventral sucker; w/ six unbranched lobes other: vitellaria extensively branched Cercaria covered with spines has ellipsoidal body and a small tail stylet present at dorsal side of oral sucker Metacercaria round measures 381-457 um. Egg Color: yellowish-brown Shell: thick Shape: oval Operculum: flattened but prominent operculum Aboperculum: thickened Unembryonated at oviposition Dimensions: 80-118um x 48-60 um

LIFE CYCLE

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Adult worms Found in pairs or in threes in fibrotic capsules or

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completion of development in the definitive host is 65 to 90 days worms persist for as long as 20 years

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Reservoir hosts: dogs, cats, field rats, rodents

PATHOGENESIS AND CLINICAL MANIFESTATIONS

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in the lungs, worms provoke a granulomatous reaction that proceeds to the development of fibrotic encapsulation within the cyst is a blood-tinged purulent material containing eggs early stages of infection are asymptomatic in heavy infections, patient may suffer from dry cough and later produce bloodstained or rust-colored sputum with foul fish odor (pronounced in the morning) Symptoms: chest pains, dyspnea, hemoptysis, low-grade fever, fatigue, myalgia often misdiagnosed for PTB symptoms less severe after five to six years complications: lodge in abdominal wall, abdominal cavity, mesenteric lymph nodes, omentum, pericardium, myocardium and intestinal wall causing erratic paragonimiasis cerebral involvement most serious and may cause: o Jacksonian epilepsy o Cerebral hemorrhage o Edema o Visual disturbances o Meningitis prognosis with light infection is good and chemotherapy has a high cure rate

DIAGNOSIS

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cysts in lungs of the host Capsules have openings that allow eggs to escape into the respiratory tract where they are moved up and out by ciliary epithelium along with lung exudates In the pharynx, are either coughed out or swallowed into the alimentary canal and passed out with feces

Eggs immature egg embryonates in water, moist soil or

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based on detection of characteristic eggs in sputum, stool, or less frequently, aspirated material from abscesses or pleural effusions serology helpful; standard test is complement fixation (CF) – has advantage to detect rapid decline in antibody levels EIA and Immunoblot (IB)

TREATMENT

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*Praziquantel; higher doses paragonimiasis Bithionol (alternative) Triclabendazole also effective

EPIDEMIOLOGY

required

in

ectopic

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global distribution in freshwater crabs major endemic areas: Asia (Japan, South Korea, Thailand, Taiwan, China and Phil.)

PREVENTION AND CONTROL

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Proper food preparation; the usual….

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a digenetic trematode that parasitizes intestines of humans and pigs mode of transmission is by ingestion of encysted metacercariae on aquatic plants or when the hull or skin of the fruits of these plants is peeled off between the teeth (?)

FASCIOLOPSIS BUSKI (intestines)

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Sporocyst and Redia miracidium transforms into sporocyst, which subsequently produces mother rediae, daughter redia and finally cercaria

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Cercaria leave daughter redia and undergo development in the snail tissues cercaria emerge 7 weeks after initial infection attach themselves on surfaces of seed pods, bulbs, stems or roots of various aquatic plants - 2nd intermediate host: water caltrop (Trapa bicornisI), water chestnut (Eliocharis tuberose), water morning glory (Ipomea obscura), and lotus (Nymphaea lotus)

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Metacercaria encyst on the surface of water plants excysts in the duodenum and attaches to the intestinal wall where it becomes sexually mature in 3 months - Infective stage: metacercaria - Definitive host: Pigs and humans

DISEASE

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Fasciolopsiasis

MORPHOLOGY

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Adult Dimensions: 20-75mm x 8-20mm (lw) Shape: elongated, oval Reproductive organs: o 2 testes are dendritic and arranged in tandem in the posterior half o branched ovary lies to the right of the midline other: o vitellaria (fine) o does not have a cephalic cone and intestinal ceca are unbranched and reach up to posterior end (as compared to F.hepatica and F.gigantica) Egg - Indistinguishable from eggs of F.hepatica and F.gigantica Large and operculated Unembryonated at oviposition Dimensions: 130-140um x 80-85um

LIFE CYCLE

PATHOGENESIS AND CLINICAL MANIFESTION

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in heavy infections, worms may be found throughout the intestinal tract and cause obstruction pathological changes caused by worms are traumatic, obstructive and toxic inflammation and ulceration occur at site of worm attachement, produces an increase in mucus secretion and minimal bleeding gland abscesses are occasionally formed intoxication results from absorption of worm metabolites by host patient experiences generalized toxic and allergic symptoms such as edema of face, abdominal wall and lower limbs profound intoxication can cause death

DIAGNOSIS • detection of parasite eggs in stool TREATMENT

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Praziquantel

EPIDEMIOLOGY

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Adult lives in the duodenum, attached to the intestinal mucosa by its suckers

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Egg immature eggs are released together with feces into the water embryonates in the water and gives rise to miracidium in three to seven weeks

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Miracidium - seeks out 1st intermediate host - 1st intermediate host: snail (genus Segmentina or Hippeutis)

endemic in countries of SEA, China, Korea and India not endemic in the Philippines (yet)

PREVENTION AND CONTROL

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metacercaria are very sensitive to dryness, soaking of aquatic plants in water should be avoided (eh? …so hindi na siya aquatic…)

time between harvest and consumption could also be prolonged to prevent infection washing of plants to remove metacercaria or boiling them can also prevent infection

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HETEROPHYID FLUKES (intestines)

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heterophyids live in the intestines of fish-eating hosts

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major species are Heterophyes heterophyes, Metagonimus yokogawai, Haplorchis taichui and Haplorchis yokogawai

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Sporocyst and Redia sporocyst develops into one or two generations of redia that give rise to cercaria

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Cercaria liberated form the snail and encyst as metacercaria on or under the scales in the muscles, fins, tails or gills of fish

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Metacercaria often found in the muscles at the base of the fin reaches duodenum and excysts liberating a young larva that attaches to intestinal wall - 2nd intermediate hosts: In the Philippines there are 30 species of fish harboring metacercaria

DISEASE

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mode of transmission is via ingestion of metacercariae encysted in fish intestinal heterophyidiasis

MORPHOLOGY

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Adult Shape: elongated, oval or pyriform Dimensions: 2mm in length Integument: fine, scale-like spines Some species have gonotyl or a genital sucker that is located near the left posterior border of the ventral sucker Reproductive organs: o testes – variously arranged; in the posterior part of body o ovary – globular or slightly lobed; located submedian, pre- or post-testicular

Metagonimus yokogawai adult

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eggs are ingested by 1st intermediate host 1st intermediate host: snails (freshwater, brackish water or marine) Miracidium hatches from the egg inside the snail transforms into a sporocyst

life cycle of Metagonimus yokogawai

Heterophyes heterophyes adult

Miracidium fully developed, symmetrical miracidium is already present w/in the egg when it is deposited by the adult worm Egg color: light brown shape: ovoid operculated; operculum fits into eggshell smoothly does not have abopercular protuberance dimensions: 20-30 um x 15-17 um

PATHOGENESIS AND CLINICAL MANIFESTATION

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Metagoniums yokogawai egg Heterophyes heterophyes egg LIFE CYCLE

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inflammation at the sites where the worm is attached to or burrowed in the mucosa excessive mucus production and sloughing off of the superficial layers may occur most common manifestions were consistent with peptic ulcer disease (PUD) or acid peptic disease (APD) symptoms: upper abdominal discomfort/pain gurgling abdomen colicky abdominal pain mucoid diarrhea In Africa, worms were shown to burrow deep into the intestinal walls and eventually die o Eggs of degenerating worms may be filtered through the intestinal lymphatics and blood vessels and deposited in various tissues o Eggs and adults of heterophyids have been observed in the heart and brain of Filipino patients who died of heart failure and intracerebral hemorrhage o Eggs can be lodged in the spinal cord and may result in sensory and motor losses

DIAGNOSIS

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• life cycle of eterophyes heterophyes

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Adult larva develops into a sexually mature adult that has a typically short life span of less than one year adult worm inhabits the small intestines of the definitive host Eggs large numbers of eggs are produced and passed out with the feces

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it is important to consider intestinal fluke infection when dealing with bowel disturbance and a history of consumption of raw fish in cases with same presentation as APD definitive diagnosis: detection of eggs in stool using the Kato-Katz method hard to distinguish between eggs of heterophyid species

TREATMENT

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Praziquantel

EPIDEMIOLOGY

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Egypt, Greece, Israel, western India, Central and South China, Japan, Korea, Taiwan and the Philippines worldwide distribution due to the fact that they have adapted to snails belonging to various families and are not very specific with respect to 2nd intermediate hosts both intermediate hosts may be found in different

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habitats (fresh, brackish and salt waters) and climates Reservor hosts: dogs, cats and birds

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PREVENTION AND CONTROL

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avoid ingestion of raw or improperly cooked fish

ECHINOSTOMA ILOCANUM (intestines)

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echinostomids are digenetic trematodes characterized by a collar of spines around their oral suckers several species infect humans (2 in the Philippines E.ilocanum and Artyfechinostomum malayanum)

Metacercaria - Cercaria develops into metacercaria in 2nd intermediate host - 2nd intermediate host: snail (Pila luzonica “kuhol” and Vivipara angularis “susong pampang”) once ingested, metacercaria excyst and juvenile flukes attach themselves to the wall of the small intestine

DISEASE

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mode of transmission is ingestion of metacercariae encysted in snails

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MORPHOLOGY

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Adults

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Color: reddish-gray Dimensions: 2.5-6.6mm x 1-1.35mm (lw) Shape: resembles coffee bean; round anteriorly, tapers posteriorly Integument: covered with single spaced spines Reproductive organs: o 2 lobed testes arranged in tandem at the third quarter of the body o ovary anterior to testes and posterior to ventral sucker; w/ six long unbranched lobes o other:  vitellaria are follicular and located in the posterior half of the body  tapered at posterior end and has 4951 collar spines  oral sucker lies in center of circumoral disk  ventral sucker situated at the anterior fifth  uterine coils found between the ovary and ventral sucker Color: straw-colored Shape: ovoid Operculated Dimensions: 83-116um x 58-69um

PATHOGENESIS AND CLINICAL MANIFESTATION

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DIAGNOSIS

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Miracidium hatches from the egg after 6-15 days infects snail - 1st intermediate host: Snail (Gyralus convexiusculus and Hippeutis umbilicalis)

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Redia No sporocyst stage develops from the miracidium inside the snail mother redia produce daughter redia and cercaria after 42-50 days

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Cercaria escapes from the snail and swims in water - seeks 2nd intermediate host

Praziquantel

EPIDEMIOLOGY

Adults once attached to the wall of the S.I., they mature sexually into adult worms live in the intestines of definitive hosts Devinitive host: Man, dogs, cats, rats, pigs Eggs released by adult worms and transported to the environment through the feces matures in water

detection of eggs in the stool echinostomes, fasciola and buski eggs look very much alike

TREATMENT

LIFE CYCLE

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heavy infections – inflammation develops at site of attachment ulceration and consequently diarrhea (sometimes bloody) and abdominal pain may develop general intoxication after absorption of metabolites of worms

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endemic in Northern Luzon, Leyte, Samar and provinces of Mindanao also in SEA and East Asian countries endemicity is related to eating habits of population 2nd intermediate host are abundant in rice fields especially during the wet months Reservoir host : rat

PREVENTION AND CONTROL

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avoiding ingestion of improperly cooked 2nd intermediate hosts

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