Blood And Tissue Parasites

BABESIA SPECIES • ZOONOSIS • Vector-IXODID tick • Resorvoir host-mice,voles and other rodents • Babesia microti-common cause of babesiosis in US

Life cycle

• Infective stage-pyriform bodies • Diagnostic stage-trophozoite • In RBC-trophozoites by binary fission

forms tetrad-lyse erythrocytes-release merozoites-reinfect • Infected cells-ingested by tickstransovarian transmission

Clinical features • Incubation period-1-4 weeks • Malaise,fever,chills,headache,fatigue • No periodicity • Progresses to develop hemolytic anemia • Splenomegaly,hepatomegaly,renal failure

Lab diagnosis • Microscopic examination of blood

smears • Resemble the ring forms of Plasmodium species • But no pigment or other stages of growth as in plasmodium

Treatment and control • DOC-Clindamycin+quinine • Exchange blood transfusion in pts

who had splenenctomy and severe infections • Protective clothing,insect repellents

TOXOPLASMA GONDII • Coccidian parasite • Reservoir host-house cat • Infective stage-sporulated oocyst • Diagnostic stage-immature oocyst in feces

• Some trophozoite forms-crescentic

tachyzoites-responsible for initial infection • Slow growing shorter formsbradyzoites-cysts in chronic infection • More severe CNS disease in immunocompromised individuals

Clinical features • Mostly-benign and asymptomatic •-

headche,myalgia,fatigue,lymphadeniti s • c/clymphadenitis,rash,hepatitis,encephal opathy,myelitis,myocarditis,chorioreti nitis-blindness

• Congenital infection• 1st trimester-spontaneous

abortion,stillbirth • Afterwardsepilepsy,encephalitis,microcephaly,intr acranial calcifications,hydrocephalus,mental retardations,blindness,anemia,jaundice ,rash,pneumonia,diarrhoea

• In immunocompromised pts-

neurological • More than one lesion in the brain • Hemiparesis,seizures,visual impairment,confusioon,lethargy

Lab diagnosis • Serological testing-increasing

antibody titre • ELISA for IgM Ab • Demonstrating trophozoites and cysts in tissue and body fluids– defenitive method • Biopsy specimens

• Monoclonal antibody based staining • Culture methods

Treatment • Pyrimethamine+sulfadiazine high

dose,then continued in lower dose indefenitely • Trimethoprim-sulfamethoxazole is another option • Steroids-if cerebral oedema develops

• Prophylaxis-

sulfamethoxazole+trimethoprim • Avoid contact with undercooked meat

FREE LIVING AMOEBA • Naegleria • Acanthamoeba • Balamuthia • Common route-Inhalation of cysts

Clinical features • Naegleria fowleri- primary

meningoencephalitis • Frontal headache,sore throat,fever,blocked nose,positive Kernigs sign • Naegleria trophozoites - in brain on postmortem

• Acanthameoba and balamuthia-

granulomatous amoebic encephalitis and brain abscess in immunocompromised individuals • Acanthamoeba-keratitis(contact with contact lens,soil,dust) • Cutaneous infection

Lab Diagnosis • Specimens-Nasal

discharge,CSF,corneal scrapings • Saline wet preparation and iodine stained smears • Naegleria-only amoeboid trophozoite;other 2-cyst and trophozoite • Can be cultured on agar plates

Treatment, prevention and control • Naegleria-amphotercin B

+miconazole and rifampin • Acanthamoebapentamidine,ketoconazole,flucytosine • Balamuthiaclarithromycin,fluconazole,sulfadiazin e,flucytosine

• Amoebic keratitis-corneal

transplantation • Cutaneous infections-topical miconazole,chlorhexidine gluconate

LEISHMANIA • Hemoflagellate • Vector-sandfly-phlebotomus

• 3 speciesLeishmania donovani -visceral

leishmaniasis(kala-azar,dum dum fever) L.Tropica -cutaneous leishmaniasis(oriental sore,Delhi boil) L.braziliensis -mucocutaneous leishmaniasis(american leishmaniasis,espundia,chiclero ulcer)

Leishmania donovani

Sandfly Transmission • transmitted via mouthparts • promastigotes regurgitated from anterior gut • factors in saliva enhance infectivity

1) promastigotes 2) phagocytosis by macrophage → amastigote 3) replication within macrophage 4) release and phagocytosis of amastigotes

4) phagocytosis of amastigotes, or ingestion by vector 5) promastigotes • replication • attachment to epithelium

6) promastigotes

• Infective stage-promastigote • Diagnostic stage-amastigote • Resorvoir host-dogs,foxes,jackals

Clinical features • Gradual onset with fever,diarrhoea,

anemia • Progresses to enlargement of organs,weight loss • Post kala azar dermal leishmaniasis in persistent cases

Visceral Leishmaniasis • 3 possibly related species • L. donovani (Asia, Africa) • India (kala azar)

• reticuloendothelial system affected • spleen, liver, bone marrow, lymph nodes

• onset is generally insidious • progressive disease • 75-95% mortality if untreated • death generally within 2 years

Clinical Presentation • incubation period • generally 2-6 months • can range 10 days to years • fever, malaise, weakness • wasting despite good appetite • spleno- and hepatomegaly, enlarged lymph nodes • depressed hematopoiesis • severe anemia • leucopenia • thrombopenia → petechial hemorrhages in mucosa

Post Kala Azar Dermal Leishmaniasis • due to inadequate treatment • nodular lesions • easily cured with treatment (in contrast to DCL)

Lab diagnosis • Amastigote stage in tissue biopsy, bone marrow examination, lymph node aspiration • Serology • Culture of blood, bone marrow demonstrates the promastigote

Treatment • 1st drug of choice-oral miltefosine • Parenteral stibogluconate • Control of resorvoir hosts,protection from sandfly bite

L.tropica • Incubation period-2 weeks-2 months • 1 st sign –red papule at the site of bite • Intense itching-enlarges and ulcerates • Exudes a serous material-secondary bacterial infection

Cutaneous Leishmaniasis • incubation period: 2 weeks to several months • chronic ulcerated, papular, or nodular lesion • lesion is painless, nontender, non-pruritic and usually clean • occasionally satellite lesions and/or palpable lymph nodes

Diffuse Cutaneous Leishmaniasis • scaly, not ulcerated, nodules • chronic and painless • numerous parasites in lesions • seldom heal despite treatment L. mexicana

Lab diagnosis • Demonstration of amastigotes in stained smears • Serology • DNA probes

Treatment • DOC-stibogluconate • Application of heat to the lesion • Protection from bites

L.braziliensis • Clinical features similar to tropica • Involvement of mucus membranes and related tissue structures • Diagnosis and treatment-same as tropica

Mucocutaneous Leishmaniasis • primarily L. braziliensis (espudia) • two stages • simple skin lesion • 2o mucosal involvement • can occur long after primary lesion (up to 16 years) • frequently in nasopharyngeal mucosae • metastasis via blood or lymphatic systems • variable types and sizes of lesions • chronic and painless

TRYPANOSOMES • T.gambiense-african

trypanosomiasis(sleeping sickness) Vector-tsetse fly • T.cruzi-chagas disease(american trypanosomiasis) Vector-reduvids

T.gambiense

• Infective stage-metacyclic

trypomastigote • Diagnostic stage-blood stream trypomastigote

Clinical features • Earliest-an ulcer at the site of bite • Followed by

lymphadenopathy,fever,myalgia,arth ralgia • Posterior cervical lymphadenopathycharacteristic-WINTERBOTTOM SIGN • c/c-CNS involvement->death

• Winterbottom's sign is the swelling of

lymph nodes (lymphadenopathy) along the back of the neck, in the posterior cervical chain of lymph nodes, as trypanosomes travel in the lymphatic fluid and cause inflammation. • It may be suggestive of cerebral infection.

Lab diagnosis • Thick and thin blood films • aspirations from lymph node,

concentrated spinal fluid • Serology,immunoflurescence,ELISA,a gglutination methods

Treatment • -Suramin is the DOC • -melarsoprol is the DOC • Control breeding sites of the vector • Protective clothing

T.Cruzi

Clinical features • Earliest-development of a

chagoma(erythematous and indurated area) • Followed by a rash and edema around eyes and face • Fever, chills and rigor • CNS involvement

• c/c-

hepatosplenomegaly,myocarditis,enl argement of oesophagus and colon • Sudden death-heart block and brain damage

Lab diagnosis • Thick and thin films • Biopsy specimens from lymph nodes, liver spleen shows the Amastigote stage. • Serology • Xenodiagnosis • PCR

Treatment • DOC-NIFURTIMOX • Also allopurinol • Bug control, eradication of nests