Lei Sh Mania

Leishmania spp. ) )leishmaniasis Cutaneous form (Oriental sore):  L. tropica, L. major, L. mexicana,   Mucocutaneous form  L. braziliensis Visceral form (Kala azar):  L. donovani (India) L.Infantum (Mediterranean form of kala azar )

Leshmaniasis geographic distribution

2 million new cases/ year (2/3 CL; 1/3 VL)

Insect vector: SAND FLY Old World Phlebotomus sp. Sergentomya sp. New World Lutzomyia sp. Brumptomya sp.

sandfly

Leishmania morphology

amastigote

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Promastigote )leptomonad) seen in sand fly

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Amastigote )leishmania) seen in the mammalian host )LD body leishmanDonovan body)

Kinetoplast

The maxicircles contain the rRNA and structural genes like  cytochrome oxidase subunits I, II, and III, cytochrome b,  

amastigote

Promastigotes of Leishmania sp.  The promastigotes are approximately 25 µm in length.

A macrophage filled with Leishmania amastigotes.

Old World Cutaneous Leishmaniasis Self-healing skin lesions L. Major and L.tropica  causes a moist, cutaneous, ulcerlike lesion at the site of the bite; it starts as a papule that runs an acute course )1-3 weeks). Natural healing of the infection )2-12 months)

• Transmission via the sand fly: • Reservoirs )gerbil, rodents, dogs) to human • Human to human. • Direct transmission Human-Human ---Primitive form of vaccination

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New World Cutaneous Leishmaniasis

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Rural diseases that are more prevalent among males who work in the forests

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 L. mexicana . The ulcer usually heals spontaneously in a few months. When the bite occurs on the ear it results in chronic lesions known as chiclero's ulcer. Because the cartilage of the ear pinna is poorly vascularized the immune response is weak, and in 40% of cases the result is mutilation of the pinna. Found principally in Central America and Mexico where it occurs in the forest dwelling people who harvest latex from the chicle trees to be used in the manufacture of chewing gum.

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Cutaneous Leishmaniasis Diagnosis • Diagnosis is made by using scrapings from the edge of the ulcer smeared on a slide and stained and examined microscopically for amastigotes.

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Diagnosis Recently PCR amplification of parasite genes has been used for diagnosis. Tissue biopsies are touched to filters and the filters are hybridized with labeled probes against parasite genes.

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Treatment Pentavalent antimonials may be used: i.e. Stilbophen )first used in 1912), or Pentostam )first used in 1947), or Glucantime )first used in 1950), but ordinarily such treatments are not necessary. Local antibiotic to avoid secondary infection

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 Control 1. Cover sores 2. Remove reservoirs 3. Remove vectors near habitation using insecticides 4. Screen against sandflies and use repellents

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MUCOCUTANEOUS LEISHMANIASIS  )occurs only in the New World)

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Beginning like cutaneous leishmaniasis and the ulcer usually heals spontaneously within 6-15 months. However, there is metastatic spread of the promastigotes from the site of the bite via the lymphatics.

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L. braziliensis: Metastatic lesion involves the nasal and buccal mucosa causing destruction and malformations of the cartilage and soft tissues. Death may occur from secondary infections or respiratory complications.

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Reservoir: sloths and anteaters

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Diagnosis: Like cuteaneous leishmaniasis

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Treatment:Treatment is usually ineffective despite intramuscular or intravenous injections of pentavalent antimonials. Secondary bacterial infections are treated with antibiotics. Liposomal amphotericin B 3mg/kg. )ISP meeting 2006) 

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Mucocutaneous leishmaniasis

sloths

• VISCERAL LEISHMANIASIS (Kala Azar) • L. donovani is the classic type found in India. • This is a metastatic disease. • Rarely is a lesion seen at the site of bite and parasites are only occasionally seen in blood, but are present in the spleen and lymph nodes. • The incubation period is 1-4 months. • Disease is characterized by fever, anemia, splenomegaly, wasting, imbalance of serum proteins )A/G ratio is reversed) and hyperpigmentation of the skin. The death rate is very high if left untreated. • Reservoir: none

Visceral Leishmania

months: fever chills, 1-4 diarrhea, dysentery Progressive hepatosplenomegaly skin hyperpigmentation Death, if untreated

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• L. infantum • Mediterranean form of kala azar • Dogs, jackals and foxes as reservoirs. •

Humans are accidental hosts.

• Principally occurs in children, but no one knows why. • Vector: P. araiasi and P. major.

Dog infected with L. infantum

Am J Trop Med Hyg. 1998 Nov;59)5):722-5.

• Emergence of visceral leishmaniasis in  central Israel. Baneth G, Dank G, Keren-Kornblatt E, Sekeles E, Adini I,  Eisenberger CL, Schnur LF, King R, Jaffe CL.

Visceral Leishmaniasis treatment •

Sodium stibogluconate or Pentastam, a derivative of antimony

Severe reactions including death occur in 10% of those treated. It is very expensive, and the recommended one month treatment costs around $150. Drug resistance has also developed. Up to 70% of infected patients in India are resistant to this drug. Pentamidine isothionate has been used in antimony-resistant visceral leishmaniasis, but although the initial response is often good, the relapse rate is high and it is associated with serious side-effects. • • •

Recently a new drug was developed, miltefosine (Impavido®). This is a  membrane signaling pathway inhibitor.  This can be taken orally and is very effective against visceral  leishmaniasis. In clinical trials has a 95% cure rate!   Miltefosine was originally developed for breast cancer but was found  in a screen to be active against Leishmania parasites by Simon Croft  in 1987. It has recently been approved for use in India.

Virulence factors inLeishmania Life inside a macrophage 1- Resistance to superoxide anion )oxydative burst): Hydroperoxide+ Reduced gluthatione ROOH + 2GSH

 ROH + 2GSSG + H20

)Lipophosphoglycan )LPG In the insect vector: 2. LPG inhibits the release of midgut proteases in the fly  4. LPG mediates the attachment of promastigotes to the gut  wall  In the mammalian host: • A direct measurement of oxidative burst in stimulated  macrophages showed that LPG inhibited this activity.  •

LPG inhibits the induction of the burst.

Glycosylphosphatidylinositol )GPI)-anchored

gp63 Major surface glycoprotein of L. major promastigotes It is a GPI-anchored zinc metalloprotease of 63 kD. The gp63 protein appears to mimic fibronectin The gp63 protein can also degrade lysosomal enzymes

The A2 gene in L. donovani and L. major •The A2 gene family was first identified in L. donovani, which is specific to the amastigote stage. •L. major does contain A2 genes, but they are not expressed and lack the multiple repeats in the protein coding regions = pseudogenes. •A2 genes are tanden repeated with a distinct gene family termed the A2erl genes. A2rel is expressed at equal levels in the promastigote and amastigote. •L. donovani amastigotes deficient in A2 protein )asRNA, gene k.o.) are attenuated with respect to survival in visceral organs of infected mice. •L. major genetically engineered to express A2 produced higher infection levels in the spleen and liver, compared to control L. major.