Leishmania major is a parasitic genus of parasitic parasites that are linked to the disease zoonotic cutaneous leishmaniasis. L. major is an intracellular pathogen that infects the immune system’s macrophages and dendritic cells. It is popularly referred to as oriental sore or kala-azar. After 2–4 weeks, an oriental sore or localised Cutaneous Leishmania occurs on the site of the sandfly bite or an insect bite. Let us explore more about oriental sore, their types of diagnosis, treatment and preventive methods.
Life Cycle of Leishmania
Leishmania is a genus of flagellate protists in the Kinetoplastida order that includes many species. These parasitic protists are transmitted to vertebrates by species of Phlebotomus, a genus of blood-sucking sand flies. The leishmanial parasites exist in two forms- a round or oval leishmanial stage that lives and multiplies in the vertebrate host, and a leptomonad, an elongate, motile, flagellated organism found in the sand fly’s alimentary tract. The species are taken in with the fly’s meal in their leishmanial stage, where they turn into leptomonads and multiply in the fly’s stomach. They finally migrate to the mouthparts of the fly, where the leptomonads enter the wound created during the next feeding, causing a new infection.
The trypanosomatid Leishmania major starts its life cycle in the midgut of the main vector, female sand flies, as an amastigote. The parasites transform from flagellated amastigotes to flagellated promastigotes in the gut of the sand fly for 1–2 weeks until they are fully grown, at which point they make their way to the proboscis.
Promastigotes are released into the bloodstream after biting a mammalian host, where they are engulfed by macrophages. Promastigotes differentiate into amastigotes after being engulfed. Amastigotes are oval or circular, with a diameter of 2 to 3 metres. They also have a big, eccentrically positioned nucleus as well as a kinetoplast that holds extracellular DNA.
The amastigotes reproduce by binary fission, a mechanism that allows them to survive the acidic environment within macrophage phagosomes. The amastigotes are then released into the body, where they can be consumed by female sand flies, completing the cycle. The sexual cycle of L. major includes a meiotic phase. The sand fly vector is the only species that mates, making it more harmful and dangerous with each multiplication.
The genus Leishmania contains three distinct species, each of which causes three distinct human diseases known as leishmaniasis. L. In Africa, Europe, and Asia, donovani causes kala-azar by attacking the liver, spleen, bone marrow, and other viscera. L. Oriental sore is caused by tropical diseases. On the skin of the hands, feet, legs, and face in Africa, Europe, and the East, lesions ranging from pimples to massive ulcers type. L. brasiliensis, which causes American leishmaniasis in Central and South America, cause similar skin lesions as well as deeper oral and nasal mucous membrane lesions.
Types of Oriental Sore or Leishmaniasis Infections
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Types |
Areas Infected |
Infection |
Symptoms |
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Cutaneous Leishmania |
The skin of the exposed areas like face, ears, arms, legs |
After being bitten by an infected sandfly, symptoms will appear weeks or months later. Affected people may develop one or more sores (skin lesions), particularly on exposed parts of their bodies and leaving noticeable scars. |
The bite site causes the lesions to grow. Papules (bumps) or nodules (solid, raised bumps), plaques (spread out and raised lesions), or ulcers (in open and eroded areas like craters) are examples of lesions. Skin lesions can shrink in size, but they often expand and do not heal. Sores may be wet and leak pus-like fluid or they can even be dry and crust over, and they are typically painless. Individuals can develop lesions that are confined to a single body part and heal on their own over 6 to 18 months. |
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Mucosal Leishmania |
Mucous membranes of Nose, Throat, Mouth |
Mucosal leishmaniasis patients usually have a skin lesion that heals on its own or with therapy, only to experience mucous membrane involvement several years or even decades later. Mucosal leishmaniasis can develop in people who have not been treated for cutaneous leishmaniasis or who have been treated ineffectively. Complications are difficult to handle and can get worse over time. |
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Visceral Leishmania |
Spleen Liver Bone Marrow |
Certain parasite species escape from the skin, invade the bloodstream, and hit internal organs, resulting in this type of leishmaniasis, which is normally the most extreme clinically. Asymptomatic infection to mild disease that resolves on its own to a serious, life-threatening infection is all possible clinical findings. It is normally fatal if symptoms occur and the full-blown disease is not treated. |
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Diagnosis
Characteristic symptoms and signs, a comprehensive case history, a thorough clinical examination, and a number of specialised tests are used to diagnose leishmaniasis. A thorough case history will reveal whether or not the patient has travelled to places where the disease is prevalent. A non-healing or progressive skin lesion in a person who has travelled to or resided in an area where leishmaniasis is found, for example, should always be considered cutaneous leishmaniasis.
Infected tissue samples are taken by doctors to be analysed. They can take a biopsy or scraping samples from skin lesions if cutaneous leishmaniasis is suspected, or from bone marrow if visceral leishmaniasis is suspected. The antibody test is only for the case of visceral leishmaniasis and not cutaneous or mucosal.
Treatment of Different Types of Leishmaniasis
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Cutaneous leishmaniasis can recover on its own, but it takes a long time and sometimes results in scarring. For small, uncomplicated lesions, treatment can involve applying heat or cold to the sores to kill the parasites or applying an antibiotic called paromomycin as an ointment directly to the sores.
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Treatment options for people with cutaneous leishmaniasis include liposomal amphotericin B, miltefosine, or sodium stibogluconate if they have many large skin lesions, a compromised immune system, or are infected with Leishmania species that may cause mucosal leishmaniasis.
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For mucosal leishmaniasis, the best treatment choice is unknown. Liposomal amphotericin B, miltefosine, and sodium stibogluconate have also been used to treat this disease. For people with serious complications of the mouth and nose mucous membranes, surgery may be needed (orofacial surgery).
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Treatment for HIV infection with antiretroviral therapy can improve the response to antileishmanial treatment, prevent or postpone leishmaniasis relapses, and improve overall survival in people with both leishmaniasis and HIV.
Prevention At Home
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Stay in places that are well-screened or air-conditioned.
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Be aware that Sandflies are much smaller than mosquitoes, so they can fit into smaller gaps to avoid even a tiny passage of entry.
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To kill insects, spray the living/sleeping areas with an insecticide.
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Use a bed net and tuck it under your mattress if you are not sleeping in a well-screened or air-conditioned area.
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Using a bed net that has been soaked in or sprayed with a pyrethroid-containing insecticide if at all necessary. Screens, curtains, and sheets should all be used in the same way, and clothes can retreat after five washes.
Conclusion
People of all ages are at risk of contracting leishmaniasis if they reside or work in areas where the disease is present. Leishmaniasis is more common in rural areas than in towns, but it can be found on the outskirts of some cities. Since sand flies are most active from dusk to dawn, the risk of transmission is greatest during this period. Adventure travellers, ecotourists, Peace Corps volunteers, missionaries, soldiers, ornithologists (people who specialise in the study of birds), and other people who do research (or are active) outdoors at night/twilight are examples of people who may be at an increased risk for infection (especially with the cutaneous form). Even though adventurous and outgoing people are at risk, care and prevention must be practised by everybody.