Microbiology 10 - Blood Flagellates PDF

Microbiology Parasitology Blood Flagellates (Hemoflagellates) Microbiology| Blood flagellates Contents : Blood flagellates 3 Old world leishmaniasis 14 New world leishmaniasis 23 Microbiology| Blood flagellates Blood and tissue flagellates has : a single nucleus. a single kinetoplast. a single flage...

Microbiology Parasitology Blood Flagellates (Hemoflagellates) Microbiology| Blood flagellates Contents : Blood flagellates 3 Old world leishmaniasis 14 New world leishmaniasis 23 Microbiology| Blood flagellates Blood and tissue flagellates has : a single nucleus. a single kinetoplast. a single flagellum. The kinetoplast consists of parabasal body and an adjacent dotlike blepharoplast. Microbiology| Blood flagellates Family Trypanosomatidae : consists of six genera, of which Leishmania and Trypanosoma are pathogenic to man. Species of this family may exist in two or more forms. Microbiology| Blood flagellates Leishmania spp. : caused Leishmaniasis (zoonosis) or (human-vector-human transmission). spread by the bite of certain types of sandflies. 1. Old world: leishmaniasis caused by L. donovani, L. infantum, L. tropica, L. major, L. aethiopica are transmitted by the sandflies genus Phlebotomus. 2. New world: leishmaniasis caused by L. mexicana, L. braziliensis and etc... are transmitted by the sandflies genus Lutzomyia. Microbiology| Blood flagellates Risk factors include : poverty malnutrition deforestation lack of sanitation urbanization Microbiology| Blood flagellates Morphology and Life cycle : Need two hosts, humans and sandflies. Natural reservoir hosts: humans, dogs and wild rodents. Occur in amastigote which is spherical or subspherical. promastigote which is pyriform or spindle shape with flagellum. Microbiology| Blood flagellates Morphology : Promastigote Insect Motile Midgut Amastigote Mammalian stage Non-motile Intracellular Microbiology| Blood flagellates When the fly bites a reservoir host or infected person with Leishmania, the pathogen reaches the stomach of the sand fly. amastigotes quickly transform into elongated and motile forms called the promastigotes (found extracellularly in the alimentary canal). Promastigotes reproducing asexually, then migrate to the proximal end of the gut. As the fly bites, the promastigotes are released from the proboscis and introduced locally at the bite site. Microbiology| Blood flagellates Once inside the human host, promastigotes invade macrophages. Inside the cells they transform back into the smaller amastigote form. The amastigotes replicate in the macrophage cell. After repeated multiplication, they break down their host cell by complete pressure of mass. New protozoans then migrate to fresh cells (Cutaneous or mucocutaneous leishmaniasis) Microbiology| Blood flagellates or through the bloodstream (visceral leishmaniasis) to find new hosts. In this way the infection is progressive, spreading to the host's mononuclear phagocyte system, particularly the spleen and liver. The free amastigotes in peripheral tissues are then ingested by sand fly to enter another cycle. Microbiology| Blood flagellates Old world leishmaniasis Microbiology| Old world leishmaniasis Cutaneous leishmaniasis (oriental sore) : caused by L. tropica, L. major, L. aethiopica. found in 88 tropical and subtropical countries. causes an open sore at the bite sites. heals in a few months to a year, leaving an unpleasant-looking scar. Diffuse cutaneous leishmaniasis produces widespread skin lesions which resemble leprosy, and may not heal on its own. Microbiology| Old world leishmaniasis Pathogenesis : Leishmania invades human macrophages and replicates. intracellularly. A raised, red lesion develops at the site of the bite (often weeks or sometimes years afterwards). The lesion secondarily infected with bacteria. Microbiology| Old world leishmaniasis Diagnosis : A skin scraping with microscopic analysis using Wright or Giemsa stain is the best test. Needle aspiration of tissue fluid from the margin of a lesion can yield fluid for culture to isolate the organism and identify the species. DNA testing (PCR). Leishmanin skin test (Montenegro test) delayed-type hypersensitivity reaction. Microbiology| Old world leishmaniasis Visceral leishmaniasis (kala-azar) : Also known as black fever, and Dumdum fever. most severe form of leishmaniasis. associated with high fatality. Caused by obligate intracellular parasite Leishmania donovani, L. infantum (infantile visceral leishmaniasis). Microbiology| Old world leishmaniasis Habitat : reticuloendothelial cells (liver, spleen, bone marrow and lymph nodes) of man and dogs. Pathogenesis : The parasite spreads from the site of inoculation to multiply in reticuloendothelial cells, especially in the liver, spleen, bone marrow and lymph nodes. This leads to progressive enlargement of these organs. Microbiology| Old world leishmaniasis Symptoms : fever enlargement of the spleen, liver and lymph nodes anemia Leucopenia skin changes Death is due to secondary infections Microbiology| Old world leishmaniasis Sometime after successful treatment—generally a few months with African kalaazar, or as much as several years with the Indian strain—a secondary form of the disease may set in, called post kala-azar dermal leishmaniasis, or PKDL. caused by the reversal of L. donovani from viscerotropic to dermatotropic. manifests first as small, measle-like skin lesions on the face, which gradually increase in size and spread over the body. Microbiology| Old world leishmaniasis Diagnosis : Non specific tests: blood count, hemoglobin and serum protein estimation. Parasitological diagnosis: blood film stained with Leishman or Giemsa stain. culture in specific media, visualization of the amastigotes in splenic or bone marrow aspirate. PCR (polymerase chain reaction) tests for the detection of Leishmania DNA. Immunological tests: Serological testing is much more frequently used in areas where leishmaniasis is endemic. New world leishmaniasis Microbiology| New world leishmaniasis Mucocutaneous leishmaniasis (espundia) : It causes both skin and mucosal ulcers damage nose and mouth. disfiguring if not treated. Caused by L. mexicana, L. braziliensis, found in certain South American nations. Severe cases can diminish the ability to eat and can be fatal. Microbiology| New world leishmaniasis Pathogenesis : Leishmania invades human macrophages and replicates intracellularly. A raised, red lesion develops at the site of the bite. The lesion may spontaneously heal with scarring, but then reappear elsewhere (especially as destructive mucocutaneous lesions). Diagnosis: as in cutaneous leishmaniasis. Microbiology| New world leishmaniasis Treatments : The treatment needed is determined by where the disease is acquired, the species of Leishmania, and the type of infection. visceral disease: liposomal amphotericin B, a combination of pentavalent antimonials and paromomycin, and miltefosine. cutaneous disease: paromomycin, fluconazole, or pentamidine may be effective. Microbiology| New world leishmaniasis Prevention : Leishmaniasis can be partly prevented by: sleeping under nets treated with insecticide. spraying insecticides to kill sandflies. treating people with the disease early to prevent further spread. reservoir control programs. Vaccination: leishmania is an intracellular pathogen since it requires strong cell mediated immunity to be controlled. However most of vaccines trials provide humoral response.