Leishmaniasis is a zoonotic disease that affects animals and is transmitted to humans. We should rather speak of leishmaniasis because this disease of parasitic origin groups three families very different in terms of symptoms and their location. We distinguish:
- Cutaneous Leishmaniasis, also known as the “Oriental Button”
- Visceral leishmaniasis, called “kala-azar”
- Mucosal leishmaniasis, where the involvement of the mucous membranes occurs in 1-3% of cases after several months of evolution of a badly or untreated cutaneous form.
In all three cases, it is a parasitosis, disease due to the contamination of the body by a parasite, the “leishmania” of which there are several families that will determine the type of attack: Leishmania donovani and infantum for the visceral form, Leishmania tropica especially for the cutaneous form, and Leishmania braziliensis for the mucous form. The parasite elects home in some white blood cells of their host, macrophages, cells responsible for cell destruction (phagocytosis).
Mode of transmission:
This parasite is transmitted to humans by an insect, a kind of mosquito called sand fly, or sand fly. Only the female feeds on blood (it is said that she is a hematophagus). She gives herself the blood of the individuals she stings at dusk, and if she is infected, she also transmits the parasite that will invade their blood.
The natural reservoir of the parasite Leishmania infantum is the dog (as well as the wild canids: foxes, jackals …), and also the cat or the hare. In other words, the sandfly is infected by pricking an infected animal, and then transmits the disease to humans.
Affected bitches can transmit the parasite to their litters.
For Leishmania donovani and Leishmania tropica, the natural reservoir is man. An infected human, if bitten by a phlebotome mosquito, can transmit the parasite to other people.
And since the immunodeficiency of HIV / AIDS increases the risk of leishmaniasis by 100, people living with HIV / AIDS are important reservoirs of parasites.
Direct human transmission can be done only through blood, for example through the exchange of syringes among drug addicts.
Sexual transmission is possible.
Incubation, ie the time between the first contact with the parasite and the appearance of the first signs of leishmaniasis, varies greatly depending on the form:
- From several weeks to several months for the cutaneous form
- 1 to 6 months at least for the visceral form
- From a few months to several years (up to 40 years!) For the mucous form
- Cutaneous form: easy to detect since it reaches the skin, especially when it concerns the face, the cutaneous form does not go unnoticed. A cut in the cutaneous lesion highlights the presence of the parasite. It is also possible to detect the parasite indirectly by performing an intradermal reaction with leishmanine (IDR), (same type of examination as the intradermoreaction for the research of tuberculosis). This involves injecting a leishmania extract under the skin and then observing that there is a cutaneous hypersensitivity reaction at the site of the injection.
- Visceral form: in addition to the signs of the pathology, the diagnosis can be made by a direct examination, of the bone marrow (myelogram), a ganglion, the blood or other fluids which finds the parasite, as well as the serology, in other words, the discovery in the blood of antibodies directed against the parasite. Be careful, the serology can be negative in case of immuno-depression, the patient being no longer able to manufacture antibodies. Finally, a blood test may show indirect signs of infection, with an intense inflammatory syndrome (high sedimentation rate), a drop in red, white blood cells and platelets. Note also the existence of a rapid test for the detection of leishmaniasis using
- Mucous form: Like the cutaneous form, it is possible to find the parasite in the oral lesions.
Prevalence of leishmaniasis
Leishmaniasis occurs in tropical and subtropical areas, encompassing 98 countries, most of which are in development. An estimated 350 million people are exposed. There are 12 million cases worldwide, for 30,000 deaths (visceral form especially). Each year, there is 1.5 to 2 million new cases. The HIV / AIDS epidemic is contributing to the increase in the number of annual cases.
Whatever the form, children, the immunocompromised (especially HIV) are particularly vulnerable.
- Cutaneous form: Leishmaniasis is common around the Mediterranean, as well as in Asia and Africa.
- Visceral form: Visceral leishmaniasis is present in China, Central Asia, India, in the Mediterranean basin.
- Mucous form: Mucosal leishmaniasis is present in Latin America especially.
|As a result of global warming, the incidence of visceral leishmaniasis is increasing in France, with an upsurge in the early days. 14 departments are at risk: Alpes-de-Haute-Provence, Alpes-Maritimes, Ardeche, Aude, Aveyron, Bouches-du-Rhone, Corsica, Drome, Gard, Herault, Lozere, Pyrenees-Orientales, Var, and Vaucluse.|
- Cutaneous form: the cutaneous form can be complicated by superinfections. Skin lesions give way to unsightly indelible scars.
- Visceral form: when it affects an immunocompromised person (HIV), leishmaniasis can be accompanied by febrile diarrhea, skin lesions that are teeming with parasites. Death is possible. In the absence of immunodepression, healing without sequelae is the rule when the treatment is set up early.
The symptoms of leishmaniasis
The symptoms depend on the form of leishmaniasis. Often, the sting goes unnoticed.
- Cutaneous leishmaniasis : the cutaneous form is manifested by one or more painless red papules (small pimples), embedded in the skin, then ulcerating and then covering with a crust, leaving after months of evolution a scar indelible. If the face is the first touched (hence the name “Oriental Button”), the cutaneous form can affect all other areas of skin discovered.
- Visceral leishmaniasisIf the cutaneous form is easily identifiable; it is not always the same for the visceral form which may go unnoticed. So-called “asymptomatic” carriers (without observable sign) are therefore frequent. When it occurs, the visceral form is first manifested by a fever at 37.8-38.5 for two to three weeks, by an alteration of the general state, a pallor, a slimming and a fatigue, an oscillating fever, difficulty breathing (for lack of red blood cells), disorders of character, nausea and vomiting, diarrhea, as well as an increase in the size of the liver (hepatomegaly) and spleen (splenomegaly), hence the name of visceral leishmaniasis. The attentive palpation found small disseminated lymph nodes (adenopathies). Finally,
- Leishmaniasis mucosa: leishmaniasis is manifested by nasal and oral lesions (infiltrated lesions, perforation of the nasal septum …), progressively destructive with a vital risk in the absence of management.
Risk factors for leishmaniasis
The risk is not the same depending on the region concerned (the disease also concerns travelers), the time of year and even during the day:
- Depending on the region concerned: the Mediterranean area concerns cutaneous and visceral forms. France seems more concerned with the visceral form due to Leishmania Infantum (Alpes-de-Haute-Provence, Alpes-Maritimes, Ardeche, Aude, Aveyron, Bouches-du-Rhone, Corsica, Drome, Gard, Herault, Lozere, Pyrenees- Orientals, Var, and Vaucluse). India and China exhibit visceral forms. East Africa concentrates cutaneous and visceral forms. In the United States, leishmaniasis can be cutaneous, visceral or mucocutaneous. In South America, leishmaniasis is mostly mucocutaneous.
- Depending on the time of year: female sandflies bite all year round in the tropics and summer in the temperate zones (France).
- The time of day: the sand fly in the first part of the night, from dusk.
Another major risk factor for visceral leishmaniasis is immuno-depression (HIV, transplants, haemopathies …). In an HIV-positive person, leishmaniasis can be considered an opportunistic disease.
Prevention of leishmaniasis
At present, there is no prophylactic (preventive) treatment and human vaccination is being studied.
The prevention of leishmaniasis includes:
- Wearing clothing covering areas at risk.
- The fight against sandflies and the destruction of parasite reservoirs.
- The use of repellents (mosquito repellent) inside and around houses (stone walls, hutches, henhouses, garbage room …).
- The use of mosquito nets impregnated with repellent. Be careful, some mosquito nets may be ineffective because the sandfly, which is small in size, can get through the mesh.
- The drying up of wetlands, like other pathologies transmitted by mosquitoes (malaria, chikungunya …).
- Vaccination in dogs (” Canileish “, Virbac laboratories).
- The treatment of the dog’s habitat (niche) by repellents and the wearing of a collar “Scalibor ” type impregnated with a powerful insecticide also has a repellent effect.
Medical treatments for leishmaniasis
- Hospitalization is essential if it is a visceral form. In fact, without treatment, the visceral form proves fatal in a few months. The drug treatment includes antiparasitic drugs derived from antimony such as Glucantime (N-methylglucamine) or Pentostam (stibiogluconate), intramuscular injection (painful).
- The treatment depends on the form of leishmaniasis (cutaneous, mucous or visceral), the extent of the lesions and the parasite species involved.
- The route of administration of the drug depends on the form: locally and generally for the cutaneous form, generally for the visceral and mucosal form.
The drug treatment includes antiparasitic drugs derived from antimony such as Glucantime (N-methyl-glucamine) or Pentostam (stibiogluconate), intramuscular injection (painful). Pentacarinat (pentamidine isethionate), certain antifungals (against fungi) such as fluconazole, ketoconazole or amphotericin B, and Impavido (miltefosine) are also used. Finally, interferon-gamma treatment with an antimony derivative appears to be effective in some forms of leishmaniasis.