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SCHISTOSOMIASIS, ONCHOCERCIASIS, LESHMANIASIS AND ACTINOMYCOSISBy

Dr. O.O. Olaofe(MBBS, MWACP, FMCPath)

• S.mansoni: geographical distribution. S.mansoni is endemic in 43 countries in Africa and occurs in the americas in Brazil, Suriname, Venezuela and in the Caribbean.• S.mansoni: intermediate host of S. mansoni are snails of the genus Biomphalaria. Releases ciliated miracidum larva• Slow moving water – slow flowing rivers, tropical lakes, irrigation ditches

Schistosoma spp.: cercariae are the infective forms.They measure about 500 micron. After encountering the skin,the cercariae penetrate and lose the tail transforming into schistosomulae.

SCHISTOSOMIASIS

• S.mansoni: adult schistosomes live in pairs in the portal system and in the mesenteric venules; males are shorter (7-12 mm in lenght and 2 mm wide) and have a ventral infolding from the ventral sucker to the posterior end forming the gynecophoric canal. Adult male with female in the copulatory groove.

• Acute schistosomiasis can be a severe febrile illness that peaks about 2 months after infection.• Chronic Schistosomiasis can manifest as severe hepatic fibrosis.• Immune response to S. mansoni and japonicum is responsible for the most important complications.

• White pinhead sized granulomas• Calcification• Infl cells• Darkened liver from regurgitated haem pigments –like malaria• Patches and pseudopolyps• Bumpy liver• Pipestem fibrosis – no regenerating nodules• Portal hypertension• Congestive splenomegaly• Oesophageal varices, Ascites• Granulomatous pulmonary arteritis, intimal hyperplasia, cor pulmonale• Membranous and mesangioproliferative GN

S haematobium• Inflammatory cystitis• Granulomas• Mucosal erosions• Haematuria• Calcify and sandy appearance• Ureteral obstruction – Obstructive uropathy• SCC

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• S.mansoni:– hepatosplenic schistosomiasisoccurs in S.mansoni and S.japonicum infections;– it results by eggs embolizationin hepatic venules with formation of granulomas and portal fibrosis. – hepatosplenomegaly, bleeding oesophageal varices and hepatic insufficiency are the more severe manifestations.

Onchcerciasis• Caused by a filarial nematode.• Leading cause of preventable blindness• Affects 18 million people in Africa, South America and Yemen.• Habitat – near fast moving water (River blindness)• Adult parasites mate in the dermis (Onchocercoma)

• O.volvulus: geographic distribution. onchocerciasis occurs especially in Tropical Africa, between the 15° north and the 13° south (high endemicity in B.Faso and Ghana). Foci are present in Southern Arabia, Yemen and in America (Mexico, Guatemala, Colombia, Ecuador, Brazil, Venezuela).The infection is transmitted by several speciesof black flies of the genus Simulium. Larva of Simulium

Pupae of Simulium(Section of an adult female). • O.volvulus: the larvae enter the host tissues, and develop to adults in subcutaneous nodules in about 1 year. Nodules are usually found in the upper part of the body in the americanonchocerchiasis and in the pelvic region in the african form.

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• Inseminated females produce microfilariae which can be disseminated to the eye• Leopard skin• Lizard skin• Elephant skin• Micro – foci of epidermal atrophy,elastic fibre breakdown, hyperkeratosis, hyperpigmentation, dermal atrophy, fibrosis, Subcutaneous Onchocercoma – Infl cellsEye lesions- Punctate keratitis, small fluffy opacities of the cornea, sclerosing keratitis, Anterior chamber- Iridocyclitis, glaucoma. Involvement of choroid and retina results in atrophy and loss of vision.

LEISHMANIASIS• It is a chronic inflammatory disease of the skin, mucous membranes, or viscera caused by obligate intracellular, kinetoplast-containing protozoan parasites transmitted through the bite of infected sandflies.• Promastigote – dev and lives extracellularly in vector• Amastigote – macrophages• Reserviors – Rodents, dogs and foxes

• Cutaneous disease– Old world – L major, L tropica– New world – L mexicana, L braziliensis

• Mucocutaneous disease (espundia)– New world – L braziliensis

• Visceral disease –Liver, spleen and bone marrow– Old world – L donovani L infantum– New world – L chagasi

• VISCERAL LEISHMANIASIS– Hepatosplenomegaly (spleen up to 3kg), – lymphadenopathy,– Pancytopenia, fever, weight loss– Fibrotic liver in late stages– Increased phagocytic cells in bone marrow, lungs, GIT, kidneys, pancreas and testes– Hyperpigmentation of skin (Kala azar)– Mesangioproliferative GN– Amyloid– Secondary bacterial infections –pneumonia, sepsis and TB– Haemorrhages due to thrombocytopaenia

CUTANEOUS LEISHMANIASIS– Relatively mild– Ulcers on exposed skin– Papule surrounded by induration --- shallow expanding ulcer – heals within 6 to 18 mthswithout Tx

• Micro –– granulomas, many giant cells, few parasites.

MUCOCUTANEOUS LEISHMANIASIS– Moist lesions (maybe ulcerating) in nasopharynx– May be destructive– Mixed infl cells – plasma, lymphocytes, parasite-filled macrophages

DIFFUSE CUTANEOUS LEISHMANIASIS– Rare, found in East Africa, Central and south America– Widespread skin nodules

Visceral leishmaniasis has a wide geographic distribution. North-Eastern China, India, Middle-East, Southern Europe (Mediterranean bassin), Northern Africa, Central-East Africa and, in foci, Central and South America (especially Brazil and Honduras).

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• The infection is transmitted by various species of Phlebotomus, the sand fly.

• Leishamnia spp. which affect humans can be differentiated by geographical distribution, clinical spectrum, immunological features, isoenzymes and Kinetoplast DNA (kDNA) characterization. (LEISHMANIA AMASTIGOTES, BONE MARROW ASPIRATE, GIEMSA STAIN).

• Visceral leishmaniasis (Kala-azar) is caused by parasites of the genus Leishmania, subgenus Leishmania, complex donovani(donovani, infantum, chagasi species). Viscerotropic strains of L.infantum and L.tropica have been described. (BONE MARROW ASPIRATE)

• Diagnosis of the infection depends on identification of amastigotes in tissues (bone marrow, spleen, liver, lymph nodes) or in blood. Other organs may be affected, expecially in HIV-1 positive patients (intestinal and respiratory tract). Amastigotes can be found inside and outside the reticuloendothelial cells. They measure 2-5 µm, are oval with a large nucleus (in red), a kinetoplast(usually perpendicular, in red to violet) and a pale blue cytoplasm. (Bone marrow aspirate).

• Visceral leishmaniasis: liver biopsy can demonstrate the Leishmania amastigotesinside the reticuloendothelial cells. The hepatic structure is preserved. • Visceral leishmaniasis: liver biopsy at higher magnification with intracellular amastigotes.

• Visceral leishmaniasis: spleen biopsy is a very high sensitive method of diagnosis but it is not widely used because of the risk of hemorrhage. Splenic tissue is rich in amastigotes allowing a rapid and sensitive diagnosis.

ACTINOMYCOSISNot very virulent (Opportunist)

– Component of Oral Flora• Periodontal pockets• Dental plaque• Tonsilar crypts

ACTINOMYCES• They are gram +ve rods.• Anaerobes• Branching and filamentous in morphology.Wrongly considered to be fungi because of:

– Morphology– Disease they cause

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Incidence:• Slight male preponderance.(1.5-1 to 3:1)• Usually 4th to 6th decade.• Three distinct forms

• A chronic suppurative and granulomatous disease of the cervico-facial, thoracic or abdominal areas • (Cervicofacial(50%),pulmonothoracic(30%) and abdominopelvic forms(20%).

• Form indurated masses with fibrous walls• Central loculations with pus

– Pus contains "Sulfur Granules"• Gritty, yellow white• Average diameter - 2mm• Composed of mineralized “mycelial”mass

CHRONIC INFECTION– Form burrowing sinus tracts to skin or mucusmembranes– This discharges purulent material

Actinomycosis - sulfur granuleCauses and risk factors.

. Five types have been described;A.Israeli, A.bovis, A.viscosus, A.naeslun-dii, A.odontolyticus.• Normally non pathogenic in the nose and throat.• It causes infection when introduced into the facial tissues by trauma, dental procedures etc.• May cause hard abscess and nodule formation; the lumpy jaw.• Except for bovis all are normal flora of the oral cavity.

Pulmonary Actinomycosis• Aspiration of organism from the oropaharynx• Poor hygiene, dental abscess, alcohol abuse

– may result in pulmonary actinomycosis.• Causes lung cavities ,nodules and pleural effusions.• 15% of cases• Slowly progressive process involving lung and pleura

– May be mistaken for malignancy• Chest pain, fever, wt loss and hemoptysis

The Cervicofacial type;Fever• Hard tender lumps with or without open sinuses mostly in and around the mandibular region• Sulfur granules in the abscess. • Wt. loss• Rarely with cervical lymphadenopathy..

Diagnosis:• Clinical findings.• Gram stain.• Culture. (poor growth in culture only in less than 50% of cases.) Sulphur granules (yellowish myecelialmasses)• Specimens – open biopsy, aspiration material• The discharge should mix with sterile saline in a universal bottle and allow to stand, particles will separate out.

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• Causes granulomatous inflammation, like chronic abscess of the neck, appendix• Yellow granules in the discharge

• Place between 2 slides• Crush and gram stain• Gram positive branching filaments

• Complications:• Osteomyelitis(although not common).• Otitis media.• Meningitis.• Lung infections.• Laryngeal infections

Thanks for Listening