Blood Flukes and Lung Flukes

• Blood Flukes ❖Schistosoma ― Schistosoma haematobium Schistosoma mansoni ― Schistosoma japonicum ― • Lung Flukes – Paragonimus westermani -Life Cycle -Clinical manifestations & pathogenesis -Diagnosis -Treatment -Epidemiology -Prevention & control Blood Flukes Schistosoma haematobium Schistosoma mansoni Schistosoma japonicum Schistosomes ➢Schistosomes are the Vascular parasites of many of warm-blooded and vertebrate animals. ➢Schistosomes are the most important parasitic worms. ➢Disease: schistosomiasis ➢The second most devastating parasitic disease (after malaria), with hundreds of millions infected worldwide. ➢At least 7 species are parasites of humans. ➢It has been estimated that about 220 million people are infected in the world in 74 countries, with 600 million at risk. ➢Schistosomiasis is distributed in parts of the tropics. Shistosoma Schistosomiasisis caused by blood trematodes. The three main species infecting humans are Schistosoma haematobium Schistosoma mansoni Schistosoma japonicum Two other species, more localized geographically, are Schistosoma intercalatum Schistosoma mekongi Other species of schistosomes, which parasitize birds and mammals, can cause Cercarial dermatitis in humans. 5 Schistosoma haematobium ➢ Humans are the only definitive host of S. haematobium. ➢Adults are found in the venous plexuses around the urinary bladder (Vesical veins). ▪ Urinary schistosomiasis. ➢Geographical Distribution: ✓ Africa: distributed throughout Africa ✓ Middle East: foumd in most countries. Iraq, Saudi Arabia, Yemen ✓ small foci in India: around Bombay & In Madras State. 6 Schistosoma mansoni ➢S. mansoni is the smallest human Schistosoma. ➢Adults are found in the inferior mesenteric veins draining the large intestine. ▪ Intestinal schistosomiasis ➢S. mansoni is the parasite of Humans & other primates (baboons, monkeys) ➢Geographical Distribution: ✓ Africa: distributed throughout Africa ✓ Middle East: Lebanon, Oman, Saudi Arabia, Somalia, Yemen. ✓ South America: including Brazil, Suriname, Venezuela. 7 Schistosoma japonicum ➢S. japonicum has a very wide host range, infecting many species of wild mammals (true zoonosis). ➢Adults are found in the superior mesenteric veins draining the small intestine. ▪ Intestinal schistosomiasis ➢Geographical Distribution: is limited to some region in Southeast Asia. ✓ Oriental blood fluke ✓ parts of China, Indonesia, Philippines & Thailand 8 Schistosoma intercalatum ➢Humans are the only definitive host of S. intercalatum. ➢Adults are found in the mesenteric veins. ▪ Intestinal schistosomiasis ➢Geographical Distribution: There are limited foci in parts of Central and West Africa 9 Schistosoma mekongi ➢S. mekongi is the parasite of Humans & Dogs. ➢Adults are found in the mesenteric veins. ▪ Intestinal schistosomiasis ➢Geographical Distribution: There are limited foci in Cambodia and Laos. 10 Life cycle of Schistosoma sp Vesical or mesenteric veins Embryonated egg Sporocysts II Sporocysts I cercariae 11 12 Schistosoma sp Adult worms of each species can live for as long as 25 years in people (3–10 years). lung Schistosomula 10 minutes portal vessels one month 5 Minutes 13 Clinical manifestations of Schistosoma I. Invasive phase II. acute phase Cercariae penetrate the skin may develop a rash or itchy skin, which is temporary III. chronic phase and will be resolved after one hour. penetration by cercariae of non-human species of schistosomes birds and mammals Cercarial dermatitis / Swimmers' itch ▪ ▪ ▪ ▪ ▪ Symptoms of swimmer's itch may include: tingling, burning, or itching of the skin small reddish pimples small blisters Scratching the areas may result in secondary bacterial infections. Itching may last up to a week or more, but will gradually go away. 14 Clinical manifestations of Schistosoma I. Invasive phase II. acute phase the immature schistosomes (schistosomula) grow into adult III. chronic phase no symptoms fever, chills cough muscle aches Katayama disease Eosinophilia up to 50% ( Early phase of S. japonicum ) ▪Allergic manifestations: fever, headache, edema, cough, dysenteric symptoms, pruritus and urticaria, occur 3–8 weeks after infection with S. japonicum. ▪Katayama syndrome may be accompanied by tenderness in the liver region, mild abdominal pain, lymphadenopathy and splenomegaly, with an accompanying eosinophilia. ▪This is possibly caused by a form of ‘serum sickness’ (acute immune complex disease) resulting from an excess of antigen when eggs are first produced. 15 16 Clinical manifestations of Schistosoma I. Invasive phase II. acute phase III. chronic phase ➢Without treatment, schistosomiasis can persist for years. ➢The majority of signs and symptoms related to the chronic phase of schistosomiasis. ➢The symptoms of chronic phase is divided into two categories: eggs and adult worms. 1) The symptoms of adult worms: comprising 20% of chronic phases symptoms. ❑ anemia ❑ Thrombosis: local coagulation or clotting of the blood in a part of the circulatory system ❑ Pigmentation , especially in liver and spleen. 17 Clinical manifestations of Schistosoma I. Invasive phase II. acute phase III. chronic phase ➢The symptoms of chronic phase is divided into two categories: eggs and adult worms. 1) The symptoms of adult worms: comprising 20% of chronic phases symptoms. 2) The symptoms of eggs: ❑ the body's reaction to the worms’ eggs is the main cause of symptoms of schistosomiasis (80%). ❑ The majority of eggs pass through the bladder or intestine but about 40% are trapped in the bladder wall or mucosa and submucosa of intestine, and eventually die and calcify and form larger granulomatous reactions. 18 intestinal Granuloma S. mansoni infestation S. japonicum Eggs within the intestinal mucosa Liver granulomata S. japonicum infestation Clinical manifestations of Schistosoma haematobium Urinary schistosomiasis Granulomata in the bladder wall ▪ Thickness of the bladder wall ▪ reduced bladder capacity increased frequency of urination ▪ Sandy patches (nests of calcified ova) ▪ Severe hematuria Anemia ▪ Stone of bladder ▪ ureteric obstruction ▪ hydronephrosis ▪ hyperplasia of the epithelium of the bladder wall ▪ Cancer of the bladder 20 Clinical manifestations of S. mansoni, S. japonicum, S. mekongi, S. intercalatum Granulomata in the intestine wall thickened mucosa megacolon abdominal pain and bloody diarrhoea papillomas Colitis S. mansoni Liver granulomata Symmers’ pipe stem periportal fibrosis 21 Intestinal schistosomiasis S. japonicum Symmer’s pipe stem fibrosis (Symmers fibrosis/ Symmer's Clay Fibrosis) The reaction to the eggs in the liver may eventually cause the periportal fibrotic reaction termed ‘Symmer’s clay pipestem’ fibrosis. 22 Clinical manifestations of S. mansoni, S. japonicum, S. mekongi, S. intercalatum Granulomata in the intestine wall thickened mucosa megacolon Intestinal schistosomiasis S. japonicum abdominal pain and bloody diarrhoea papillomas Colitis S. mansoni Liver granulomata Symmers’ pipe stem periportal fibrosis portal hypertention Ascites: the accumulation of fluid in the peritoneal cavity, causing abdominal swelling. Hepatomegaly Hepatosplenomegaly 23 Hepatosplenic abdominal distension schistosomiasis secondary to chronic S. japonicum infection CT scan of the brain demonstrates a right cerebral hemisphere lesion due to S. japonicum. The patient presented with focal motor seizures. Rarely, eggs are found in the brain or spinal cord and can cause seizures, paralysis, or spinal cord inflammation. The more severe pathology thought to be produced by infection with S. japonicum is usually explained by the greater egg production, the spherical shape of the egg lacking a large spine resulting in more eggs being distributed throughout the body, and the greater longevity of the adult worms. 24 granuloma that forms around the egg Schistosoma ova in intestinal cross-section Eggs of Schistosoma haematobium detected in the bladder Schistosoma japonicum ova in intestinal villi 25 S. japonicum creating lesions in this liver section Schistosoma mansoni female inside the gynecophoral groove of the male crosssection in liver tissue 26 Diagnosis Clinical In the field, haematuria can provide a quick and inexpensive indicator of urinary Schistosomiasis. Ultrasound can be used for diagnosis of the degree of pathology, particularly in the liver or bladder. Parasitological The microscopic identification of eggs in the stool or urine. Immunological ELISA Dipstick-ELISA Treatment  Praziquantel is the drug of choice. 27 Epidemiology ▪Human contact with water is thus necessary for infection by schistosomes. ▪Schistosomiasis is an important cause of disease in many parts of the world, most commonly in places with poor sanitation. ▪In endemic areas, school-age children are often most at risk because they tend to spend time swimming or bathing in water containing infectious cercariae. Prevention and Control ❑ Personal prevention is by avoidance of water sources containing cercariae. ❑ There are four principal methods of control: ❑ mass chemotherapy ❑ destruction of snails ❑ environmental sanitation ❑ prevention of water contact 28 Lung Flukes Paragonimus westermani 29 Paragonimus westermani ➢Paragonimus is a lung fluke. ➢P. westermani is a natural parasite of carnivores, especially in the members of the cat family, such as the tiger, leopard and domestic cat. ➢Geographical distribution: P. westermani is widely distributed. ➢Human infection reported from Far East. ➢The adults are typically found in pulmonary cysts, usually in pairs. 30 Life cycle of Paragonimus westermani The adult worms can live for 20 years but usually die after about 6 years. adult worms in lungs Fresh water crab or crayfish Miracidium rediae sporocysts Fresh water snail 31 Clinical manifestations of Paragonimus westermani ❑light infections no symptoms ❑heavy infections ▪the migratory phases no symptoms ❑ in lung ▪Fever with a dry cough ▪bloodstained sputum containing eggs after rupture of the cysts ▪Eosinophilia up to 40-50% ▪Chest pain, dyspnea and bronchitis ▪Many patients with hemoptysis are diagnosed as pulmonary tuberculosis. Cerebral paragonimiasis may result in epileptic seizures, as well as headaches, visual disturbances and symptoms of meningitis. Diagnosis Clinical A cough with brown sputum Characteristic nodular or ring shadows apparent on X-ray or Computer assisted tomography (CT) scan can be recognized by an expert, but the disease is often mistaken for tuberculosis. Parasitological the microscopic identification of eggs in sputum or the stool. Immunological ELISA Treatment  Praziquantel is the drug of choice. 33 Epidemiology ▪Paragonimiasis can be contracted from both raw and pickled crabs and crayfish. ▪Specialty dishes in which shellfish are consumed raw or prepared only in vinegar, brine, or wine without cooking play a key role in the transmission of paragonimiasis. ▪Raw crabs or crayfish are also used in traditional medicine practices in Korea, Japan, and some parts of Africa. Prevention and Control ❑ Personal prevention is by avoidance of eat raw freshwater crabs or crayfish. ❑ Cook crabs and crayfish for to at least in water at 55°C for 5 min. 34 Cercaria liberated from snail Encystment to give metacercaria, which is ingested by definitive host Active penetration of skin of definitive host Schistosoma Encystment on vegetation 2nd intermediate host required Fasciola Fasciolopsis Fish crab or crayfish Ant Clonorchis Opisthorchis Heterophyes Metagonimus Paragonimus Dicrocoelium