Clinical Parasitology PDF - Parasitology, 1st Semester

PARA311: CLINICAL PARASITOLOGY TOPIC: SPOROZOA [Plasmodium spp. and Babesia spp.] 1ST SEMESTER | S.Y 2024-2025 LECTURER: Prof. Rose Dyane Hizola, RMT, MPH TOPIC - Babesi...

PARA311: CLINICAL PARASITOLOGY TOPIC: SPOROZOA [Plasmodium spp. and Babesia spp.] 1ST SEMESTER | S.Y 2024-2025 LECTURER: Prof. Rose Dyane Hizola, RMT, MPH TOPIC - Babesia spp. SUBTOPIC o Babesia microti SUB SUBTOPIC o Babesia divergens o Babesia bovis - Cryptosporidium hominis Protozoan parasites are characterized by the production - Cyclospora cayetanesis of spores like oocysts [spore-like oocysts] - Isospora belli Live intercellular during the part of their life cycle - Toxoplasma gondii - They need one organism to complete their life cycle Phylum Microspora They are also classified under Phylum apicomplexa - Enterocytozon bineusi because of their apical complex - There are certain structures needed for attachment - Encephalitozoon spp. or penetration to host cells - Vittaforma cornea - Pleistophora spp. CLASSIFICATION OF PROTOZOAN PARASITES - Brachila vesicularum - Microsporidium spp. MALARIA from Italian word “mal’aria” which means “bad air” - “mal” meaning bad - “aria” meaning air - Malaria: bad air During 18th century in Italy, it is believeed to be caused of foul emanation from the marshy soil - Galing sa mabahong odor na nanggaling sa lupa Considered to be the most important parasitic disease affecting man (Belizario, 2015) Phylum Apicomplexa Vector: female Anopheles mosquito - Plasmodium spp. o Plasmodium falciparum – responsible for 1 ̊ [Primary vector]: Anopheles minimus var. flavirostris 90% of the malarial cases Others: Anopheles litoralis, Anopheles maculates, o Plasmodium vivax – responsible for 90% of Anopheles mangyamus the malarial cases Final Host: Female Anopheles mosquito o Plasmodium malariae Intermediate Host: Man/Humans o Plasmodium ovale Infective stages: sporozoites (man); gametocytes o Plasmodium knowlesi – 5th human malarial (mosquito) parasite; not usually common in human - Sexual stage: happens in the mosquitoes [usually in monkeys, but in the Philippines, o Infective stage: gametocytes there has been a reported case of this - Asexual stage: happens in humans parasite (last 2006)] o Infective stage: sporozoites 1|Page J.M.J.R.  Malaria has been identified by the World Health SOURCES OF EXPOSURE TO INFECTION Organization as one of the three major infectious Vector-borne (Arthropod borne) disease threats, along with Human Immunodeficiency Other modes of transmission: Virus/Acquired Immune Deficiency Syndrome and 1. Imported malaria Tuberculosis o From other countries endemic with malaria - Increasing cases of malaria especially during the and transfer the disease with other people rainy season 2. Transfusion malaria Malaria mostly affects young children and pregnant o During blood donations women 3. Mainline malaria - Especially in endemic areas [prone na makagat ng o Sharing of needles (drug users) lamok] 4. Congenital malaria PERIODICITY/FEBRILE CYCLE o Vertical transmission via placenta [mother to fetus] Malarial diseases are referred to their outstanding Vector Biology: Anopheles flavirostris clinical features – fever or febrile cycle Aquatic Habitat: slow flowing streams; shaded streams - Interval of acquisition of fever - Also the habitat for dengue mosquitoes - Water sources that are not moving or slow moving Adult biting: Night biting (indoor and outdoor) Adult resting: inside walls THE MOSQUITO CYCLE Plasmodium knowlesi – Quotidian malaria [24 hrs; every 24 hrs, nagkakaroon ng fever] Tertian – 48 hours Subtertian – 36-48 hours Quartan – 72 hours Falciparum, vivax, ovale – fever appears every second day or alternate days Malariae – every 3rd day ang labas ng fever Life cycle of malarial parasites typically involves 2 hosts: Malaria – associated with P. falciparum human (intermediate host) and mosquito (definitive host) 2|Page J.M.J.R.  Sexual phase happens on female anopheles mosquito - Dito nangyayari ‘yung formation ng sporozoites [sporogony phase] - Maturation and fertilization takes place inside the body of the mosquito [Sexual Cycle or Sexual Multiplication] When a female mosquito bites and sucks the blood of the human host, it will go to the stomach and the blood may contain the female and male gametocyte In the mosquito, the male and female gametocyte will undergo maturation - microgametes/microgametocytes: male; - macrogametes/macrogametocytes: female o fertilization will happen = formation of zygote o when they form a zygote, it will become elongated and active o once in an active form, it will form ookinetes will penetrate the stomach wall of the mosquito and develops into an oocysts o oocysts will continue to grow and develop and may form a slender or thread-like form Exflagellating male gametocytes: the nuclear material that will be called as sporozoite and cytoplasm of the male gametocytes divides to o the oocysts will be ruptured [releasing produce 8 microgametes with long, actively motile, sporozoite]; released throughout the body whip-like filaments. of the mosquito The female gametocyte does not divide but undergoes a o those sporozoites will undergo a cycle process of maturation to become the female gamete or [mapupunta sa salivary glands ng mosquito; macrogamete. It is fertilized by one of the kaya kapag nakakagat, mappenetrate sa host or human] microgametes to produce the zygote. - there are sporozoites that will go to the salivary Ookinete: the zygote, which is initially a motionless, glands of mosquito, but there are also sporozoites round body, gradually elongates becomes a vermicular that will go to the liver of human [will be the cause motile (traveling vermicule) form with an apical of asexual multiplication or the pre-erythrocytic or complex anteriorly. exoerythrocytic cycle] Oocyst: rounded into a sphere with an elastic o salivary glands: cycle is called sporogonium membrane within which numerous sporozoites are o liver: cycle is called pre-erythrocytic or formed. exoerythrocytic Sporozoites: when the oocysts ruptures, the sporozoites - the sexual phase or the sporogony cycle or enter into the hemocele or body cavity, from where mosquito cycle does not only depend on the specie some find their way to the mosquito’s salivary glands. of plasmodium, but also to the mosquito host The mosquito is now infective and when it feeds on o may mga specie na mas mabilis ang humans, the sporozoites are injected into skin multiplication inside the mosquito capillaries to initiate human infection. [depending on the temperature of the environment] 3|Page J.M.J.R.  o example: Plasmodium vivax has the fastest o Important stage because in this stage sexual stage [8 days]; Plasmodium malariae parasites can invade the erythrocytes has 35 days of sexual stage In the erythrocytic cycle, the merozoites will invade the Red Blood Cells, but some of them like Plasmodium vivax and ovale will reinvade the liver cells - Once bumalik sila sa liver cells, there will be a dormant stage [sleeping stage or called as hipnozoites] - These parasites that invade the red blood cells in the bloodstream, they will undergo erythrocytic cycle that will last up to 44-72 hours. - For each infected red cell, the product will be 4-36 new parasites At the end of the schizogony cycle, the infected red cells will rupture, liberating all merozoites to infect new red cells - Ruptured red blood cells will liberate products of metabolism of parasites - Not all red blood cells will undergo metabolism [hemozoin: pigment of hemoglobin] - During the rupture of red blood cell, doon nangyayari ang fever or lagnat - From liver -> rupture liver cells -> infect red blood cells PRE-ERYTHROCYTIC (TISSUE) STAGE OR EXOERYTHROCYTIC STAGE [SCHIZOGONY OR ASEXUAL CYCLE] The hepatocyte is distended by the enlarging schizont Asexual multiplication is called as Schizogony stage or and the liver cell nucleus is pushed to the periphery Schizogony cycle These normally rupture in 6-15 days and release This happens in the liver thousands of merozoites into the blood stream - The sporozoites enter or infect the liver cells = Hypnozoites (hypnos: sleep): resting forms in schizonts [term used to call sporozoites that has Plasmodium vivax and Plasmodium ovale entered the liver] - The rupture of infected liver cells will release the merozoites into the circulation o Enter and infect the red blood cell [erythrocytic cycle] - Schizogony stage: malarial parasites multiplies by dividing or splitting the process designated to shizogoniae = to form schizonts o Occurs in two locations: liver Plasmodium falciparum and Plasmodium malariae – has [exoerythrocytic cycle] and in the red blood no sleeping stage; completely undergo the three cycles cell [erythrocytic cycle] in all of the 4 species, asexual multiplication takes place in the liver cells, but in the case of Plasmodium vivax 4|Page J.M.J.R.  and Plasmodium ovale, they will undergo dormant or The appearance of malaria pigments varies in different sleeping stage species as follows: - sporozoites will enter sleeping or dormant stage = - P vivax: numerous fine golden-brown dust-like hypnozoites particle - P. falciparum: few 1–3 solid blocks of black pigment ERYTHROCYTIC STAGE - P. malariae: numerous coarse dark brown particles The merozoites released by pre-erythrocytic schizonts - P ovale: numerous blackish brown particles. invade the red blood cell: Amoeboid form or late trophozoite form: as the ring - The receptor for merozoites is glycophorin, which is form develops, it enlarges in size becoming irregular in a major glycoprotein on the red cells. shape and shows amoeboid motility. - Merozoites are pear-shaped bodies, about 1.5 μm When the amoeboid form reaches a certain stage of in length, possessing an apical complex (rhoptery). development, its nucleus starts dividing by mitosis They attach to the erythrocytes by their apex. followed by a division of cytoplasm to become mature - Ring forms or young trophozoites: the merozoite schizonts or meronts. loses its internal organelles and appears as a The merozoites invade fresh erythrocytes within which rounded body having a vacuole in the center with they go through the same process of development. the cytoplasm pushed to the periphery and the The rupture of the mature schizont releases large nucleus at one pole. quantities of pyrogens. - Malaria pigment or haemozoin pigment: parasite This is responsible for the febrile paroxysms feeds on the hemoglobin of the erythrocyte but it characterizing malaria. does not metabolize hemoglobin completely and therefore, leaves behind a hematin-globin pigment as residue. P. vivax: signet ring appearance with schuffner’s dots [fine red granules] P. malariae: elongated band or stab, stretching to the entirety of red blood cells [the dots are called as Plasmodium vivax – described as the delicate ring Ziemann’s stippling] - Called as “vivax” because it means in latin is P. falciparum: compact with cytoplasmic vacuolation; vigorous [malilikot] almost ring-shaped, but with dark red or wedge-shaped Plasmodium malariae – compact ring dots [Maurer’s dots] Plasmodium falciparum – very delicate ring P. ovale: malarial’s stipplings are called Jame’s dots Plasmodium ovale – dense ring Accole forms: crescentic masses (moon-shaped; peripheral part of the red blood cells) - P. falciparum has accole forms 5|Page J.M.J.R.  Male gametocytes: blunted edges Female gametocytes: pointed edges P. malariae: flower-like appearance ; daisy-head - Average merozoites: 8 GAMETOGONY Development of gametocytes generally takes place within the internal organs and only the mature forms COMPONENTS OF THE MALARIA LIFE CYCLE appear in circulation. The mature gametocytes are round in shape, except in P. falciparum, in which they are crescent-shaped or sausage-shaped. In all species, the female gametocyte is larger (macrogametocyte) than the male gametocyte (microgametocyte). The gametocytes do not cause any clinical illness in the host, but are essential for transmission of the infection. A gametocyte concentration of 12 or more per cumm of blood in the human host is necessary for mosquitoes to become infected. 6|Page J.M.J.R.  INTERVALS MALIGNANT TERTIAN MALARIA The most serious and fatal type of malaria is malignant tertian malaria caused by P. falciparum. PERNICIOUS MALARIA Pernicious malaria has been applied to a complex of life-threatening complications that sometimes supervene in acute falciparum malaria. CEREBRAL MALARIA Incubation period: time between the sporozoite Cerebral Malaria: is the most common cause of death injection and appearance of clinical signs and symptoms in malignant malaria, capillary plugging of cerebral - Depends on the parasite strain, immune status of microvasculature, which results in anoxia, ischemia, human, and depending on the sporozoite entered and hemorrhage in brain. BLACKWATER FEVER CLINICAL FEATURE Blackwater fever: malarial hemoglobinuria, is sometimes seen in falciparum malaria. Clinical BENIGN MALARIA manifestation include bilious vomiting and The typical picture of malaria consists of periodic bouts prostration, with passage of dark red or blackish of fever with rigor, followed by anemia and urine (black water). splenomegaly. Severe headache, nausea, and vomiting There is a massive intravascular hemolysis caused by are common. anti-erythrocyte antibodies, leading to massive absorption of hemoglobin by the renal tubules CLASSICAL MALARIA PAROXYSMS (hemoglobinuric nephrosis) 1. COLD STAGE ALGID MALARIA - Starts with the sudden coldness and Algid Malaria: peripheral circulatory failure, rapid apprehension thready pulse with low blood pressure, and cold - mild shivering turns to teeth chattering and clammy skin. There may be severe abdominal pain, shaking of the whole body vomiting, diarrhea, and profound shock. - may last for 15 to 60 minutes SEPTICEMIC MALARIA 2. HOT STAGE/ FLUSH PHASE : BEST STAGE TO COLLECT Septicemic malaria: high continuous fever with BLOOD SAMPLE dissemination of the parasite to various organs, - high temperature (40-41 C ̊ ) [best time to collect leading to multiorgan failure. Death occurs in 80% of blood sample], headache, palpitations, epigastric the cases. discomfort, thirst, nausea and vomiting MEROZOITE-INDUCED MALARIA - patient is confused and delirious Injection of merozoites can lead to direct infection of - may last for 2 to 6 hours red cells and erythrocytic schizogony with clinical 3. SWEATING STAGE (DEFERVESCENCE OR illness. Such merozoite-induced malaria may occur in DIAPHORESIS) transfusion malaria, congenital malaria, renal - Defervescence: disappearance or lowering of transplantation and mainline malaria. fever TROPICAL SPLENOMEGALY SYNDROME - Diaphoresis: excessive sweating due to fever Also known as hyper-reactive malarial splenomegaly - profuse sweating, temperature lowers and (HMS) is a chronic benign condition seen in some symptoms diminishes adults in endemic areas, mainly tropical Africa, New - may last for 2 to 4 hours Guinea, and and Vietnam. Abnormal immunological response to malaria causing splenomegaly, high titers of circulating anti-malaria antibodies and absence of malaria parasites in peripheral blood smears, hypergammaglobulinemia 7|Page J.M.J.R.  (IgM), cryoglobulinemia reduced C3, and presence of rheumatoid factor without arthritis. Recrudescence: new malarial attacks that appear after a period of latency usually within 8 weeks after the primary attack and resulting from persistence of the erythrocytic cycle of the parasites. Relapse: common to P. vivax and P. ovale infections, as result from the reactivation of hypnozoite forms of the parasite in the liver. PATHOLOGICAL PROCESS OF THE RBC 1. Poikilocytosis and Anisocytosis 2. Altered RBC membrane transport 3. RBC stiffness and cytoplasmic viscosity IMMUNITY DUFFY NEGATIVE RBCs MORPHOLOGY It has been found that persons, who lack the Duffy blood group (Fya and Fyb alleles) antigen, are refractory to infection by P. vivax. These genetically determined blood group antigen appears to be the specific receptor for P. vivax. NATURE OF HEMOGLOBIN Hemoglobin E provides natural protection against P. vivax. P. falciparum does not multiply properly in sickled red cells containing HbS. Sickle cell anemia trait is very common in Africa, where falciparum malaria is hyperendemic and offers a survival advantage. HbF present in neonates protects them against all Plasmodium species. - If there’s a problem in the hemoglobin of red blood cells, it can’t be targeted by the malarial parasites 8|Page J.M.J.R.  G6PD DEFICIENCY Innate immunity to malaria has also been related to G6PD deficiency found in Mediterranean coast, TREATMENT Africa, Middle East, and India. PROTECTIVE - The red blood cells here are bite cells; resistant to Chemoprophylaxis: Objective is to prevent infections Plasmodium falciparum in non-immune person visiting endemic areas HLA-B53 (Mefloquine and Doxycycline) HLA-B53 is associated with protection from malaria. CURATIVE There is some evidence that severe malnutrition and Therapeutic: Objective is to eradicate the erythocytic iron deficiency may confer some protection against cycle and clinical cure. malaria. Radical cure: Objective is to eradicate the exoerythrocytic cycle in liver to prevent relapse. - Artemether-Lumefantrine (Coartem TM) – first DIAGNOSIS line drug for confirmed P. falciparum cases. Not MICROSCOPY (GOLD STANDARD) recommended in pregnancy, lactation and “THICK AND THIN BLOOD SMEAR” infants. stained with Giemsa or Wright’s stain - Quinine (plus Tetracycline or Doxycycline) – perform multiple sets of blood films (blood collected second line drug for confirmed P. falciparum every 6 to 12 hours for up to 48 hours) cases which AL fail or not available. MANNER OF REPORTING - Quinine IV drip – drug of choice for complicated A. QUALITATIVE or severe P. falciparum malaria. PREVENTIVE Gametocidal: Objective is to destroy gametocytes to prevent mosquito transmission and thereby reducing human reservoir. - In addition to AL and Q+T,D, Primaquine is given B. QUANTITATIVE on the 4th day as single dose to prevent transmission QUANTITATIVE BUFFY COAT (QBC) PREVENTION uses a special capillary tube with acridine orange (+) bright green and yellow under fluorescent 1. Use of mosquito repellant microscope 2. Use of insecticide treated nets (ITN) RAPID DIAGNOSTIC TEST (RDT) 3. Take prophylactic medication detects Plasmodium-specific antigens in finger prick 4. Wearing of light-colored clothing which cover most of sample the body A. Histidine-rich protein II (HRP II) – water soluble CONTROL CHON produced by trophozoites and young gametocytes (e.g., Paracheck Pf test, ParaHIT f 1. Environmental cleanliness test) - (stream cleaning to speed up water flow and B. Plasmodium LDH – produced by both sexual and exposing to sunlight) asexual stages and can distinguish between P. 2. Indoor residual sprayin falciparum and non-P. falciparum (DiaMed 3. Zooprophylaxis – use of carabao to deviate mosquitoes OptiMAL IT) 4. Use of biologic control methods SEROLOGIC TESTS a. Bacillus thuringiensis – larvicidal IHA, IFAT, ELISA b. Larviparous fishes (e.g., Oreochromis niloticus) MOLECULAR METHODS Through PCR (low cases and mixed infection) 9|Page J.M.J.R.  Plasmodium knowlesi A primate malarial parasite common in South East Asia Causes malaria in long tailed macaques (Macaca fascicularis) May also infect humans The appearance of P. knowlesi is similar to that of P. malariae. PCR assay and molecular characterization are the most reliable methods for detecting and diagnosing P. knowlesi infection However, P. vivax appears to interfere PCR testing (cross-reactivity) Babesia spp. (Babesia microti, Babesia divergens and Babesia bovis) First described to cause “Texas cattle fever or red water fever” Blood parasites that cause malaria-like infections “Babesiosis” – pathology due to Babesia spp. Life cycle of Babesia spp. undergo three stages: Parasites divide through binary fission or budding 1. Merogony in the red blood cells of tick vectors Cycle in the tick is still uncertain 2. Stage in the gut and epithelium Vector: Ticks (Ixodes scapularis) 3. Sporogony in humans c. Hard ticks Babesia infected tick once nakakagat, need magkroon d. Scapularis – capable of carrying Borrelia burgdorferi ng contact for 12 hours para magkaroon ng effective → CA of Lyme disease transmission Definitive Host: Ixodid ticks - That cycle will infect the red blood cells producing Intermediate Host: Man or other mammals merozoites and trophozoites, producing continuous Infective form: Sporozoites cycle, but the diagnostic characteristic is the Mode of Transmission: bite of the nymphal stage of maltese cross or tetrads formation Ixodid ticks - In humans, merozoites, from infected cells -> Other modes of transmission: infecting red blood cell e. Blood transfusion In mouse, merozoites will form gametes. Once gametes f. Organ transplantation are ingested by another tick, they will travel through the g. Transplacental route gut of the tick for fertilization to form zygote and Diagnostic stage: “Maltese cross” – arrangement of the transform intro ookinete to infect another host merozoites and ring-form trophozoite Sporogony happens resulting to numerous release of sporozoite. Once sporozoite is released, it will be transmitted to another host 10 | P a g e J.M.J.R.  PATHOLOGY Associated with excessive pro-inflammatory cytokines such as the tumor necrosis factor (TNF) Most cases are subclinical and may occur as self- limiting Headache, high-grade fever, chills, vomiting, myalgia, DIC, hypotension, respiratory distress and renal insufficiency. DIAGNOSIS 1. Microscopy of the Giemsa-stained peripheral blood smear A. Merozoites in Maltese cross arrangement B. Ring form → most frequent intraerthrocytic form found 2. PCR (gold standard) 3. Immunofluorescent assays (IFA) 4. Immunochromatographic test (ICT) 5. Hamster Intraperitoneal Inoculation TREATMENT Clindamycin – Drug of choice Drug combination: Clindamycin and Quinine or Azithromycin and Atovaquone Chloroquine – former drug of choice (it only improve the symptoms but not the degree of the parasitemia) In the Philippines: human babesiosis is not yet reported however, it could be present in dogs (Babesia canis). PREVENTION AND CONTROL avoidance of places where ticks are usually found wearing of light-colored pants tucked into one’s socks tick check (especially for children) rodent population should be controlled 11 | P a g e J.M.J.R.