The Most Common Parasitic Infections In Yemen. Medical Parasitology

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1 The Most Common Parasitic Infections In Yemen Medical Parasitology ﻓﺎﯾز اﻟﺧوﻻﻧﻲ / د

2 2

3 : is a vector-borne disease that transmitted by sandflies and caused by obligate intracellular protozoa of the genus Leishmania. About 21 of 30 species cause human infection. The different species are morphologically indistinguishable, but they can be differentiated by isoenzyme analysis, molecular methods, or monoclonal antibodies. The following table summarizes the clinical diseases caused by the most important Leishmania species. Leishmania species Disease Visceral L. donovani L. infantum L. chagasi L. tropica L. major L. aethiopica L. mexicana L. mazonensis leishmaniasis Cutaneous L. mexicana leishmaniasis Diffuse-cutaneous L. aethiopica leishmaniasis (DCL) Muco-cutaneous L. braziliensis L. panamensis leishmaniasis (MCL 3

4 Epidemiology and Distribution is endemic in 88 countries with an estimated 350 million people at risk of infection. The overall prevalence of the leishmaniasis estimated to be at 12 million cases with 0.5 million new visceral leishmaniasis cases per year and million new cutaneous leishmaniasis cases per year. More than 90% of visceral leishmaniasis occurs in Sudan, Bangladesh, Nepal, Brazil and India, and more than 90% of cutaneous leishmaniasis in Brazil, Peru, Afghanistan, Syria, Iran, Yemen and Saudi Arabia. In recent years, there have been major epidemics of visceral leishmaniasis in southern Sudan, eastern India, Bangladesh, and Brazil. Increased infections and the spread of leishmaniasis is related to environmental and behavioral changes and development, conflict and war, bringing non-immune people into closer contact with vectors and reservoir hosts. Transmission and life cycle Leishmania is mostly zoonotic (transmitted to humans from animals), and humans become infected only when accidentally exposed to the natural transmission cycle. However, humans are the sole reservoir hosts when the transmission occurs from human to human through the sand fly vector. 4

5 Leishmania species are transmitted by the bite of an infected female sandfly, belonging to the genus Phlebotomus in Africa, Asia and Europe, and the genus Lutzomyia in the Americas. About 30 species of sandflies act as vectors, infecting humans and animal reservoir hosts. Pattern of transmission Human-to-human transmission: man is the only source and reservoir of infection. Dog-to-human transmission: The infection source is domestic dogs and some rodents, which acts as a reservoir host. Classification of leishmaniasis according to the location NEW WORLD OLD WORLD (South America and Central (Africa, Asia, Europe) America) Leishmania species Leishmania species L. donovani L. chagasi Visceral leishmaniasis L. infantum Cutaneous leishmaniasis L. tropica L. major L. aethiopica L. guyanensis L. amazonensis L. Mexicana Diffuse cutaneous leishmaniasis L. aethiopica L. Mexicana L. amazonensis Mucocutaneous leishmaniasis L. braziliensis L. panamensis 5

6 Sandfly vectors The feeding, breeding and flight habits of sandflies are species specific. Most sandflies feed mainly on plant juices, but female flies also require blood meals for egg development. Most species feed at night, dusk or dawn. Morphology The parasite exists in two forms: 1. Amastigote 2. Promastigote Amastigote Amastigotes are round in man and other vertebrate hosts. Amastigotes live inside monocytes, polymorphonuclear leucocytes. They are small, round to oval bodies measuring μm in length (Fig below). They are stained well with Giemsa or Wright stain. In the stained preparation, the cytoplasm appears pale-blue and surrounded by a limiting membrane. The nucleus relatively is large and stained red. The kinetoplast lies at right angle to the nucleus. It is slender, rod-shaped and is stained deep red. Axoneme arises from the kinetoplast and extends to margin of the body. Vacuole, which is a clear unstained space, lies alongside the axoneme. 6

7 Leishmania. Amastigote Promastigote Promastigotes are excited in the digestive tract of sand fly (vector) and in the culture media. The fully developed promastigotes are long, slender and spindle-shaped. They measure 14.3 to 20 μm in length and 1.5to 1.8 μm in breadth. A single nucleus lies at the center. The kinetoplast lies transversely near the anterior end. The flagellum is single, delicate and measures15-28 um. With Leishman stain, cytoplasm appears blue, the nucleus pink and the kinetoplast blight red (Figure below). 7

8 Fig. ( ) Leishmania species Promastigote Life cycle in man The life cycle of Leishmania species is summarized in Fig below. It consists of two forms: amastigote, which presents in the human macrophages and promastigote, which presents in the sandfly and culture media. Life cycle of Leishmania species involves two hosts: human host (vertebrate host) and insect host (vector host, invertebrate host). Because it is not identified the sexual stages of the parasite, the definitive host is not recognized yet. The life cycle begins with injection the infective stage metacyclic promastigote into the human host at the time of taking blood meal by the female sandfly. The skin macrophages phagocytize the promastigotes by a process of phagocytosis then transform into intracellular forms called amastigotes. 8

9 Amstigotes multiply within skin macrophages (in case of cutaneous leishmaniasis), liberate from the macrophages, and infect new cells. In visceral leishmaniasis, the amastigotes multiply in the macrophages of the spleen, liver, bone marrow and lymph glands of the reticuloendothelial system. Blood monocytes are also infected. Life cycle in sandfly When intracellular and free amastigotes are ingested by a female sandfly the life cycle is continued After about 72 hours, the amastigotes become flagellated promastigotes in the midgut of the sandfly. They multiply and fill the lumen of the gut. After days (depending on species), the promastigotes move forward to the head and mouth-parts of the sandfly. Sandfly the leishmaniasis vector 9

10 Injection of metacyclic promastigote the infective stage into the human skin Life cycle of Leishmania 10

11 Symptoms of Visceral leishmaniasis (VL) This is the most severe form of leishmaniasis. It is caused by L. donovani and L. infantum in the old world and L. chagasi in the new world. In the endemic areas, the disease is more chronic with young adults and children being more commonly infected. In epidemics, all age groups are susceptible (except those with acquired immunity), and the disease is often acute. Without treatment, VL is usually fatal. Symptoms in acute VL, there is splenomegaly, high undulating fever with two peaks in the day, chills, profuse sweating, weight loss, fatigue, anaemia, and leucopenia. Symptoms in chronic VL include irregular fever, massive splenomegaly, hepatomegaly, and/or lymphadenopathy, marked loss of weight with wasting, diarrhea, low white cell and platelet counts, and anaemia. The local Indian name for VL, kala-azar (meaning black sickness or black fever) is a reference to the darken color of the infected patients. Malnutrition and other infections increase the risk of developing symptomatic VL. 11

Massive splenomegaly in VL Post kala-azar dermal leishmaniasis (PKDL) In India and occasionally in Africa, a cutaneous form of leishmaniasis can occur about 2

This is referred to as post kala-azar dermal leishmaniasis and affects about 20% of patients in India.

12 Massive splenomegaly in VL Post kala-azar dermal leishmaniasis (PKDL) In India and occasionally in Africa, a cutaneous form of leishmaniasis can occur about 2 years after treatment and recovery from visceral leishmaniasis. This is referred to as post kala-azar dermal leishmaniasis and affects about 20% of patients in India. Hypopigmented and raised erythematous patches appear on the face, trunk of the body, and limbs. These may develop into nodules and resemble those of lepromatous leprosy, fungal infections or other skin disorders. Occasionally there is ulceration of the lips and tongue. Amastigotes are present in the papules and nodules. 12

13 Figure ( ) PKDL in sudan Figure ( Figure ( Papular and nodular PKDL ) PKDL affecting the earlobe ) PKDL: macular lesions, some are confluent. 13

14 Immunity Absence of Gamma Interferon IFN ᵧ and Interleukin 2 during Active Visceral Inhibition of parasitic Ag presentation by the antigen presenting cells (APCs)-macrophage because lysis of intracellular amastigote is blocked. Leishmania proamastigote has surface inhibiter molecules called lipophosphoglycan (LPG) that inhibits the toxic effect of macrophage nitric oxide. Nitric oxide or nitrogen mediators are a potent toxic oxidant that destroys intracellular pathogens however, promastigote of leishmania parasite has the ability of inhibition the nitric oxide-dependent killing mechanism of the macrophage. Because the acidic ph is an environment suitable for living and multiplication of the amastigote, thus lysis of intra-phagosome amstigote does not achieved by the macrophage lysosomes. As a result, rupture of parasitized phagocyte occurs and releasing of amastigotes that in turn infects other macrophages. T lymphocytes are not activated unless recognizes the pathogen Ag which must be expressed on the surface macrophage. 14

Macrophages have the key role in an initiating the cell-mediated immune response, and one of some immune cells that act as an antigen presenting cells.

15 Macrophages have the key role in an initiating the cell-mediated immune response, and one of some immune cells that act as an antigen presenting cells. In normal phagocytosis, the phagocyte lysosomes destructs the intracellular pathogen into small peptides, these peptides are then expressed on the macrophage surface via the Major Histocompatibility molecules class 1(MHC molecules). After an antigen presenting, macrophage release a cytokines molecules called Il-2 and INF ᵧ, which activate T lymphocytes. The consequences of T lymphocytes activation is the direct killing of infected cells and controlling the disease prognosis. 15

16 Illustration of leishmania parasite during invasion of macrophage 16

17 Development of the immune response to protozoan and helminth infection 17

18 Cutaneous leishmaniasis (CL) Cutaneous leishmaniasis is a potentially severe and disfiguring disease in some people. The clinical forms of CL vary according to the species of parasite, region, and immune response of the patient. People with cutaneous leishmaniasis have one or several long-lasting lesions on the skin, usually without fever or general symptoms. New cases are emerging in areas previously free of the disease. Over new cases of cutaneous leishmaniasis are reported annually to WHO by countries in the Region, but the actual incidence is estimated to be three to five times higher since many patients never 18

seek medical attention and not all patients with a diagnosis of cutaneous leishmaniasis are reported to health authorities. Old world cutaneous leishmaniasis (CL) Cutaneous leishmaniasis caused by L.

19 seek medical attention and not all patients with a diagnosis of cutaneous leishmaniasis are reported to health authorities. Old world cutaneous leishmaniasis (CL) Cutaneous leishmaniasis caused by L. tropica Infection is often referred to as dry urban oriental sore. Dry painless ulcers mm in diameter are produced which are self-healing usually after 1 2 years but often leave disfiguring scars. The patient acquires immune to reinfection. Rarely, multiple unhealed lesions may develop, often on the face. It can last many years and is difficult to treat; this condition is known as leishmaniasis recidivans (LR). Untreated LR may leads to destruction and disfiguration of the infected parts. Initial brownish nodule of dry, urban type of cutaneous leishmaniasis 19

20 Plaque lesion of dry, urban type of cutaneous leishmaniasis Dry, urban and anthroponotic type of cutaneous leishmaniasis recidivans due to (L. tropica) from Morocco.Note the healed scar from which new lesions develop. 20

2014-2015 Chronic cutaneous leishmanaisis of face with areas of scarring and reactivation of disease ( recidivans) recidivans due to (L. tropica) from Afghanistan.

21 Chronic cutaneous leishmanaisis of face with areas of scarring and reactivation of disease ( recidivans) recidivans due to (L. tropica) from Afghanistan. Note the healed scars from which new lesions develop. Cutaneous leishmaniasis caused by L. major Infection is often referred to as wet oriental sore. The early papule is often inflamed and resembles a boil of 5 10 mm in diameter which rapidly develops into a large uneven ulcer which is self-healing in as little as 3 6 months. Multiple lesions may occur in non-immune persons. L. major infections show permanent immunity against reinfection. 21

2014-2015 Wet ulcer in CL Cutaneous leishmaniasis caused by L.

often associated with scaling. This form is known as diffuse cutaneous leishmaniasis.

22 Wet ulcer in CL Cutaneous leishmaniasis caused by L. aethiopica A cutaneous lesion that is similar to typical oriental sore with healing in 1 3 years. Localized cutaneous lesions may spread to involve large cutaneous area, forming a nodules often associated with scaling. This form is known as diffuse cutaneous leishmaniasis. The patients who have diffuse cutaneous leishmaniasis are more likely of little or no cell -mediated immunity against the parasite. Chronic localized cutaneous leishmanisis of face Non-healing chronic cutaneous leishmaniasis 22

2014-2015 Diffuse cutaneous leishmaniasis (DCL) Both L. aethiopica (Old World) and L. amazonensis (New World) are the causes of diffuse cutaneous leishmaniasis.

23 Diffuse cutaneous leishmaniasis (DCL) Both L. aethiopica (Old World) and L. amazonensis (New World) are the causes of diffuse cutaneous leishmaniasis. Skin lesions develop over a large area of the body. The lesions on the eyebrows, nose and ears resemble those of lepromatous leprosy. At first, the lesions are smooth, and firm. Later they become scaly and rough. The nodules contain large numbers of amastigotes. The lesions do not heal spontaneously and this is an incurable condition characterized by the formation of disfiguring nodules over the surface of the body. DCL caused by L. amazonensis is resistant to treatment. DCL caused by L. aethiopica, relapses occur after treatment. Diffuse cutaneous leishmaniasis- Venezuela 23

2014-2015 Diffuse Cutaneous (DCL) from Ethiopia. The patient originating from the Highlands where CL and not VL is endemic; there is no previous history of VL.

24 Diffuse Cutaneous (DCL) from Ethiopia. The patient originating from the Highlands where CL and not VL is endemic; there is no previous history of VL. Leishmania parasites were found in a skin scraping. Mucocutaneous leishmaniasis (MCL) In New World, both L. braziliensis and L. panamensis can cause Mucocutaneous leishmaniasis (MCL). In south America Mucocutaneous leishmaniasis (MCL) known as, espundia. Rarely MCL is caused by L. tropica and L. aethiopica in the old world. MCL is the most severe and destructive form of cutaneous leishmaniasis in South America. Lesions are similar in development to those of oriental sore and the resulting ulcers may become very large and long lasting. 24

2014-2015 Disfiguration is extreme with complete destruction of the infected part, such as nasal septum if the nose is the primary lesion and damage to the tissues of the lips and ear cartilage.

25 Disfiguration is extreme with complete destruction of the infected part, such as nasal septum if the nose is the primary lesion and damage to the tissues of the lips and ear cartilage. Mucosal lesions do not heal spontaneously and severe secondary bacterial infections can occur. A Sudanese form of MCL is referred to as oro-nasal leishmaniasis. Mucocutaneous leishmaniasis (MCL) Treatment of Most sores will heal spontaneously within one year. Treatment of cutaneous and muco-cutaneous leishmaniasis is the same while the latter needs more intensive treatment due to the more severe and destructive complications. 25

26 Pentavalent antimony: Pentostam Unfortunately, some cases of leishmaniasis may treated by topical steroid preparation. This changes the clinical picture, deteriorates the lesion, which becomes later more chronic and decreases its response to the specific medications. For adults, we give 6 cc of Pentostam I.M. daily for 10 days. This usually gives very good results, causing rapid healing of the ulcers. The dose is adjusted according to the age (20 mg/kg of body weight). Neostibosan Neostibosan (Bayer): is also an effective medication. The daily dose is 5mg/kg body weight. A dose of mg. can be given for older children and adults daily for 16 days is proved to be effective. Patients with diffuse cutaneous leishmaniasis require treatment for a longer time. Liposomal amphotericin-b (AmBisome ) Is the drug of choice for VL. It is given in a dose of 3 mg/kg per day on days 1-5, day 14 and day

27 Laboratory Diagnosis Diagnosis of visceral leishmaniasis The laboratory diagnosis of visceral leishmaniasis (VL) is by: Finding amastigotes in: o material aspirated from the spleen, bone marrow or an enlarged lymph node, nasal secretion. o peripheral blood monocytes and less commonly in neutrophils (buffy coat preparations). Culturing aspirates and peripheral blood and examining cultures for promastigotes. Other tests Formol gel (aldehyde) test. This is a non-specific screening test which detects marked increases in IgG. Large amounts of polyclonal nonspecific immunoglobulin are produced by patients with active VL. Haematological investigations including: o measurement of haemoglobin, o total and differential white cell (leukocyte) count, o platelet (thrombocyte) count. Detection of anti-leishmanial antibody In visceral leishmaniasis, specific antibody as well as non-specific polyclonal Ig G and Ig M are produced. 27

28 Several techniques have been developed to detect and measure specific anti-leishmanial antibodies in patients sera. Those being used in district laboratories and field surveys include: Direct agglutination test (DAT) or rk39 dipstick to detect anti-rk39 antibody. Diagnosis of cutaneous and mucocutaneous The laboratory diagnosis of CL and MCL is by: Detecting amastigotes in smears taken from infected ulcers or nodules. In MCL, the parasites are scanty and difficult to find in smears. Culturing ulcer material and examining cultures for promastigotes. Serological diagnosis of CL and MCL Because of the poor antibody response in CL, serological tests are of little value in diagnosis. Leishmanin skin test (Montenegro test) It is a delayed hypersensitivity skin test. In this test, 0.2ml of Leishmania antigen (containing 100,000,000 promastigotes of L. donovani in l ml of 0.5% phenol saline) is injected intradermally. The test is read after 48 to 72 hours. A positive test shows an area of erythema and induration of 5 mm in diameter or larger, which heals in days. 28

29 Positive reaction indicates prior exposure to leishmanial parasites. In kala-azar, the skin test becomes positive usually only 6 to 8 weeks after cure from the disease, it is negative in active cases. Culture of ulcer material Culture is of value when cutaneous leishmaniasis is suspected and parasites cannot be found in smears. Measures to prevent and control leishmaniasis Early detection and treatment of infected persons, especially in areas where humans are the only or important reservoirs of infection. Personal protection from sandfly bites by: Using insect repellants, although in hot and humid conditions they are of limited use due to profuse sweating. Avoiding endemic areas especially at times when sandflies are most active. Use of insecticide impregnated bed nets and curtains. Vector control by the use of light traps, sticky paper traps, or residual insecticide spraying of houses and farm buildings where this is practical, or alternatively using insecticide paints in a slow-release emulsifiable solution. Destruction of stray dogs and infected domestic dogs in areas where dogs are the main reservoir hosts. 29

30 Elimination and control of rodents in areas where these are sources of human infections. Leishmania amastigotes in Giemsa stained skin slit smear. Leishmania amastigotes in monocyte in a Giemsa stained blood film. Giemsa stained amastigotes of L.donovani. Right: As seen in bone marrow. Left: As seen in splenic aspirate. 30

31 Formol gel test showing positive (+ ) and negative ( - ) reactions. 31

HAEMOFLAGELLATES. Dr. Anuluck Junkum Department of Parasitology Faculty of Medicine

HAEMOFLAGELLATES. Dr. Anuluck Junkum Department of Parasitology Faculty of Medicine HAEMOFLAGELLATES Dr. Anuluck Junkum Department of Parasitology Faculty of Medicine Objective Can describe the morphology, life cycle, pathology, diagnosis and prevention of Leishmania spp. and Trypanosoma