Spray living/sleeping areas with an insecticide to kill insects.If you are not sleeping in a well-screened or air-conditioned area, use a bed net and tuck it under your mattress. If possible, use a bed net that has been soaked in or sprayed with a pyrethroid-containing insecticide (permethrin or deltamethrin). The same treatment can be applied to screens, curtains, sheets, and clothing (clothing should be retreated after five washings).Source:http://www.cdc.gov/parasites/leishmaniasis/prevent.html
Learning Objectives1. Define and classify parasites.2. Explain the pathogenesis of parasite.3. Define leishmaniasis.4. Mention the types & causes, risk factors, signs & symptoms, diagnosis, complications, treatment & prevention.5. Explain the life cycle of Leishmania.
What is a parasite ?• A parasite is an organism that benefits from a close prolonged relationship with its host, which is harmed.• The parasite grows, feeds, or uses shelter of the host organism (including the host itself) contributing negatively to the relationship.• May be ectoparasites or endoparasites which can be intra- or extra- cellular
Parasitic pathogenesis• Given the wide diversity among human parasites, the pathogenesis is highly variable.• Although the human parasites exhibit direct pathogenic mechanisms, in most instances the organisms themselves are not highly virulent!
Parasitic pathogenesis Exposure and Entry Adherence and Replication Disruption, Evasion, and Inactivation of Host Defenses
1. Exposure and Entering Ingestion. Arthropod bite Trans-placental Direct penetration penetration Organism-directed penetration
2.a. AdherenceMediated byPhysical ChemicalMechanical or biting mouthparts. interaction between parasite surface glycoproteins (adhesins) and specific glycoprotein or glycolipid receptors.
2.b. Replication• Parasites replicate intracellularly or extracellularly in human• Helminthes generally do not replicate.• Temperature is important for the ability to infect and cause disease.
Disruption, Evasion, and Inactivation of Host Defenses • Like other organisms, parasites elicit humoral and cell-mediated immune responses. • parasites are particularly adept at interfering with or avoiding these defense mechanisms.Antigenic variation,Molecular mimicry & Intra-cellular location Immuno-suppression Masking
What is leishmaniasis ?• Leishmaniasis is an infectious disease• caused by parasites belonging to genus Leishmania• generally transmitted by the bite of infected female Phlebotomus sand fly.
Leishmaniasis types & causesCutaneous leishmaniasis (CL)• Caused by L. major, L. tropica & L. mexicana.• The most common form.• Days to few weeks.• on the extremities and face.
Leishmaniasis types & causesMucocutaneous leishmaniasis(ML)• Caused by L. braziliensis.• Not treated cutaneous lesion on the face spreads to the nose or mouth.• Months to years.• Lesions can be very disfiguring
Leishmaniasis types & causesVisceral leishmaniasis (VL)• Caused by L. donovani, L. infantum & L. chagasi.• Most severe form of the disease, fatal if untreated• Visceral disease from the Middle East is usually milder.
Cutaneous Mucocutaneous Visceralone lesion or initially a nodule at Sever weight lossmultiple lesions the bite of the sand flylarge scaly, nodules inside the Pancytopeniaulcerated plaques, nose, perforation ofor shallow ulcerated the nasal septum,nodules and enlargement of the nose or lipsexpanding and Change in voice Hepatosplenomegalyulcerating over timedry or weeping Intermittent feverpainful if secondarily Disfiguring scarring Hypergamma-infected and tissue globulinemia destructionSwollen lymph nodes Dark skinnear the sores.
Diagnosis• A physical exam may show an enlarged spleen, liver, and lymph nodes. The patient may have been bitten by sandflies, or was in an area known for leishmaniasis.
Differential diagnosis• Cutaneous leishmaniasis (CL) may look like other skin diseases, especially lepromatous leprosy, sarcoidosis, and skin cancer.• Visceral leishmaniasis (VL) may resemble malaria or haematological malignancies.• Mucocutaneous leishmaniasis (ML) may be similar to Tertiary syphilis.
Visceral Biopsy and culture of liver,spleen, bone marrow, or lymph nodesLeishmania-specific PCR test Indirect immuno-fluorescent antibody test Direct agglutination assay
Complication• Fatal infections - due to immune system damage• Bleeding (hemorrhage) VL• Facial disfigurement ML• ruptured spleen VL
TreatmentAntimony-containing Other drugs : Surgery compounds :• meglumine • Pentamidine: • Plastic surgery antimonate. CL (ML).• sodium • amphotericin • Splenectomy stibogluconate. in drug- resistant (VL).
PrognosisCutaneous Mucocutaneous VisceralLocalized cutaneous relatively resistant to Untreated visceralleishmaniasis lesions treatment. leishmaniasis has ausually heal 90% death rate, butthemselves completely. only a 10% death rateDiffuse cutaneous with treatment.leishmaniasis maysmolder on for yearswithout treatment
PreventionPreventing sand fly bites is the most immediateform of protection. You can prevent a bite by:• Putting fine mesh netting around the bed• Screening windows• Wearing insect repellent• Wearing protective clothing• Public health measures to reduce the sandfly population and animal reservoirs.• There are no vaccines or drugs that prevent leishmaniasis