cestodes and trematodes infestation of the lung

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clinical aspects of Parasitic flat worm infestations of the lungs


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PARASITIC LUNG DISEASES : CESTODES & TREMATODES By Dr. Mahmoud Alsalahy Assist prof of Chest Medicine Banha University, Egypt

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ECHINOCOCCOSIS: Caused by Echinococcus granulosus (dog tapeworm) and multilocularis (fox tapeworm) Cause hydatid disease (cystic & alveolar) The definitive host is canines esp. dogs & foxes Intermediate host: sheep, goats, kangaroo and other herbivores Worldwide distribution but most common in Mediterranean, south and central america , Russia, China & sub-Saharan Africa E. multilocularis is endemic in northern hemisphere E.granulosus is more common but E.multilocularis is more pathogenetic CESTODES

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Pathogenesis and pathology: Cysts enlarge very slowly: 1cm/ yr in liver and 5cm/ yr in lung May take decades before symptomatizing Cyst has 3 layers: Pericyst: fibrous layer by the host tissue Exocyst : carbohydrate rich, parasite derived, laminated layer Endocyst : germinal layer, produce protoscolices, cyst fluid Symptoms develop due to complications: ▪ Compression ▪ Rupture ▪ Infection In E. multilocularis, pericyst is poor → tumor like behavior Liver affected in 60%, lung in 20-30%, 10% other sites In lungs: More on right (65% vs. 35%) More in lower lobes (65% vs. 35%) Solitary cyst in 80% Associated liver disease in 10-40%

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Clinically: Latent period of 5-15 yr , so common after age of 20 Asymptomatic for decades Pulmonary symptoms in 70-90% : cough, fever, chest pain, sometimes hemoptysis Bilioptysis and pneumothorax and pleuritis are rare Cyst rupture (30%): expectoration of watery fluid with salty and peppery taste, may be parts of the cyst Anaphylaxis with respiratory failure may occure with rupture Rarely a cyst ruptures in pleura, pericardium or mediastinum Infected cyst (30%): picture of lung abscess Vascular: Pulmonary embolism if rupture in hepatic veins or PA Aortic pseudo aneurysm

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Diagnosis: Suspected if relation to dogs was positive in a clinically and radiologically compatible picture X-ray: A homogenous round or oval shadow Air crescent sign if pericyst rupture Water Lilly sign if endocyst rupture A cavity with air fluid level Pleural effusion Cyst wall may calcify CT: changes in X-ray are better seen in CT MRI: Cyst and daughter cysts are well seen on T1 while capsule is well seen on T2 Bronchoscopy is not recommended unless malignancy is possible Immunodiagnosis: Serodiagnosis: is 96% sensitive and specific Echinococcin test: intra dermal injection of echinococcus protein s NB. Aspiration of cysts must be avoided if hydatid disease is suspected

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Treatment: Surgical removal is the best for resectable cysts Peri -operative albendazol in 10-15 mg/kg/day in 2 doses at least 4 days before resection and continued for at least 1 month after surgery For E. multilocularis a safety margin must be resected with cysts Addition of praziquantel 25mg/kg/day for 1 month before surgery is more effective Non surgical candidates are treated by Albendazol for prolonged time and for life in E. multilocularis Medical treatment offers cure in 50% Puncture, Aspiration, Injection, reaspiration (PAIR) hepatic cysts Prevention: Dog deworming Dog vaccination Sanitation

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TREMATODES PARAGONIMIASIS: (PULMONARY DISTOMATOSIS, ENDEMIC HEMOPTYSIS) Caused by Paragonimus species 43 species, 12 infect humans, P. Westermani (lung fluke) is the most important Most endemic in Southeastern Asia, central and south America, west of Africa Infection is by eating under cooked crustaceans esp. crabs and crayfish or from contaminated utensils Definitive host: crustaceans eating mammals like dogs, cats, bears Man is accidental definitive host 2 intermediate hosts, snails (1 st ) and crustaceans (2 nd ) Adult worms live in small peribronchial cysts

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Pathogenesis and pathology: Passage of cercariae through the pleura cause eosinophilic effusion Passage through the lungs cause hemorrhagic eosinophilic pneumonitis Near the bronchioles worms settle, become walled off by fibrous wall making small cysts that communicate with bronchial lumen and pass eggs In 1-24% of patients, CNS is involved with hemorrhagic encephalitis Characteristically serum, BAL, and pleural fluid contain high levels of IL-5

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Clinically: Symptoms develop 6-27 months after infection Pleurisy, effusion and pneumothorax can occur during passage through pleura In brain: cause headache, dizziness and visual troubles, epilepsy and mental impairment Pulmonary symptoms: Cough: 60-100% Hemoptysis: 60-95% of chocolate rusty sputum, fresh blood is unusual Chest pain: 40-95%, pleuritic Disease is debilitating and may be mistaken for TB Physical examination is usually normal: signs of effusion, pneumothorax, crepitations

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Diagnosis: Suspected in those eating undercooked crabs Golden brown operculated eggs in sputum samples is the gold standard but need repeated testing X-ray: most lesions are midzonal 10-20% free Effusion: most common 50-60% Consolidation is next most common Nodules, interstitial, bronchiectasis like cysts, pneumothorax CT: changes in X-ray are better seen in CT Bronchoscopy: To investigate hemoptysis Bronchial washings and biopsies show eggs Immunodiagnosis: Serodiagnosis: is 96% sensitive and specific Paragonimus extract skin test: intra dermal injection of parasite proteins

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Treatment: Praziquantel : 25mg/kg/day divided in 3 doses for 2 days Triclabendazol : 20 mg/kg in two equal doses Corticosteroids : if cerebral disease is present Prevention: Treat patients Good hygiene Well cooking of crustaceans

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SCHISTOSOMIASIS: Caused by Schistosoma species 5 species infect humans one of them is zoonotic: S. Mansoni : in Africa, Middle East, south America and Caribbean S. Hematobium: in Africa , Middle East, south America and parts of India S. Japonicum: in South-East of Asia (zoonosis from cows) S. Intercalatum : in central Africa S. Mekongi : in Cambodia and Laos 200 millions are infected, 20 millions with severe disease, 650 millions at risk worldwide Peak severity in 15-20 yrs , repeated infection is common Infection starts by skin penetration by cercariae from fresh water snails (intermediate host)

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Schistosoma mansoni geographical distribution

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Pathogenesis and pathology: Passage of cercariae through the skin cause local reaction and itch Passage through blood cause Katayama fever, a serum sickness like syndrome while in lungs cause eosinophilic pneumonia Acute response is down regulated and parasites settle and mature in abdominal venous plexuses and mate to lie eggs Eggs penetrate mucosa to pass out with stool or urine causing GIT or urinary symptoms Many eggs are retained in tissues causing granulomas, many get embolized in portal venules in the liver causing fibrosis and portal hypertension When porto -pulmonary shunts develop, eggs embolize to pulmonary arterioles causing inflammation, obstruction and pulmonary hypertension PH occurs in 7-23% and cor pulmonale in 5% of patients with hepatosplenomegally S. mansoni is the main pathogenic type to the lung

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Clinically: Swimmer ´s itch on infection Katayama fever occurs 3-8 wks after infection GIT symptoms: pains, flatulence, dysentery, bleeding per rectum (10-12 wks later) Urinary symptoms: burning micturition, terminal hematuria (10-12 wks later) Pulmonary symptoms: Katayama fever: Cough: 5 0-80% Dyspnea: 50% Chest pain: 40% May be fatal in S. japonicum With pulmonary H++: Same as other etiologies Physical examination is usually normal in Katayama fever but later signs are those of PH ++

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Diagnosis: Swimmer itch must be suspected in endemic areas Katayama fever: serology IgM anti-worm antibodies (20-30 days post infection) Eggs in stool, urine or mucosal samples are the gold standard: mean egg count is of prognostic value GIT and Urinary investigations for evidence of disease Bilharzial egg antigen and antibodies: settled after 1-6 months X-ray: May be free Nodules with ill-defined borders, beeded linear shadows, interstitial pattern Consolidation may be seen in acute stage Of PH++ CT: changes in X-ray are better seen in CT

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Treatment: Praziquantel : kills adult worms and eggs only 40mg/kg divided in 2 doses 12 hrs apart for S. mansoni and hematobium gives 75-100% cure rate 60 mg/kg over 24 hrs in 3 doses for S japonicum In acute stage can worsen clinical picture Steroids may be needed but reduce efficacy Non viable eggs can be shed for long time after treatment which must be considered in follow up Prevention: Treat patients: national campaigns Covered irrigation systems Molluscicides for fresh water snails Education: how to prevent infection

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1. Protozoan infections of the lung include all of the followings except: Pneumocystis carinii Plasmodium vivax Toxoplasma gondii Entameba histolytica Trypanosoma cruzi 2. As regards pulmonary entamoeba infection: Is a zoonotic disease Mainly reach the lung by lymphatics Only one route of infection All of the above Non of the above

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3 . In amoebic lung abscess: Patient general condition is usually good Always occur in lower lobe on the right side Best treatment is by metronidazol 200 mg t.d.s /1 week Cure is possible Non of the above 4 . As regards pulmonary malaria infection: A zoonotic disease Lung commonly involved in falciparum disease Always severe disease occur with ARDS All of the above Non of the above

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5 . A patient had fever for few days after a month abroad in South Africa, he got black urine followed by severe dyspnea and cyanosis: The patient must receive 100% high flow oxygen Chloroquine phosphate should be included in his therapy The patient will not require assisted ventilation All of the above Non of the above 6 . As regards pulmonary toxoplasmosis: A zoonotic disease Infection is usually asymptomatic X ray findings are non specific All of the above Non of the above

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7 . All the followings are risk factors for amebic lung abscess except: Poor hygiene Crowded population Mentally retarded Homosexuals House hold pets 8 . As regards pulmonary toxoplasmosis all are false except: Lung is the only involved organ Airways are never affected No treatment is required Immune suppression has no role Radiological changes are non specific

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9 . Ascaris worms can cause all the following except: High IgE Upper airways obstruction Simple pulmonary eosinophilia Loffler pneumonia Tropical pulmonary eosinophilia 10. For nematode associated lung disease: Dirofilariasis is a common disease Trichnellosis cause lung abscess All are non zoonotic in origin All of the above Non of the above

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11. Regarding TPE all the following are wrong except: Caused by dirofilaria Eosinophilia occurs in 20-50% Prevalent in tropics and subtropics Best treatment is triclabendazole The commonest radiological pattern is lung collapse 12. Pulmonary visceral larva migrans means: Ascaris lumbricoides larvae migrating to the lung Migration of filaria larvae through the lung A zoonotic disease from canines All of the above Non of the above

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13. For pulmonary distomatosis, all the following are wrong except: Caused by schistosoma intercalatum Commonest complaint is chest pain Man is the definitive host Best treatment is co- trimoxazole The commonest radiological pattern is ring shadows and cysts in a background of consolidation 14. Pulmonary paragonimiasis : Caused by paragonimus westermani Endemic disease in SE Asia Best treatment is praziquantel All of the above Non of the above

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15. In pulmonary bilharziasis, all the following are true except: Mainly caused by schistosoma mansoni Very common in middle east and Africa Man is the definitive host for all species Best treatment is praziquntel Late stages are not curable 14. All are wrong for Katayama fever except: Caused by fungal spore inhalation Lasts only few days after infection Steroids are useless in its management Is a synonym to swimmer itch Eosinophilic pneumonitis may be of its components

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16. The parasitic disease that may mimic pulmonary TB is: Visceral larva migrans Lung bilharziasis Pulmonary distomatosis All of the above Non of the above 17. Radiological findings in pulmonary hydatidosis can include: No abnormality Unilateral opacification of a hemithorax A lung abscess or abscesses Lung collapse All of the above Non of the above

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18. A 40 yr old farmer presented to outpatient chest clinic by heaviness in Rt. Hemithorax . X-ray revealed a subpleural large well defined, oval shaped homogenous opacity with possible calcification in the wall. Further evaluation of this case may include all of the following except: Serology Trial of Aspiration CT chest and upper abdomen Bronchoscopy A skin test 19. The best treatment of the above patient could be: Surgery Treatment of the causative agent by drugs Leave undisturbed with follow up PAIR Marsupialization

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