BMS201 Plasmodium, Anopheles, Babesia, Hard Tick PDF Fall 2024

BMS201 Lecture No: 1 and 2 Title: Plasmodium spp. and Malaria, Anopheles vector Babesia spp. and Babesiosis, hard tick vector Prof. Khalifa E. Khalifa Medicine and Surgery Program Fall 2024 By th...

BMS201 Lecture No: 1 and 2 Title: Plasmodium spp. and Malaria, Anopheles vector Babesia spp. and Babesiosis, hard tick vector Prof. Khalifa E. Khalifa Medicine and Surgery Program Fall 2024 By the end of this lecture, you should be able to: 1. List the different Plasmodium spp. causing malaria 2. Locate the Geographical distribution of the different Plasmodium spp. 3. Describe life cycle in man and vector, infective stages, modes of infection, and diagnostic stages of Plasmodium spp. 4. Discuss the clinical manifestations of malaria and its complications. 5. Analyze and interpret the finding of case studies of malaria. 6. Outline the diagnostic methods of malaria and identify the different morphologic forms present in peripheral blood film. 7. Outline treatment and preventive measures of malaria including chemoprophylaxis. 8. Identify the Anopheline vector of malaria and differentiate it from the culicine vector of Wuchereria bancrofti from morphological character. 9. Outline the control measures of malaria vector Do You Remember: Study Objectives 1. Geographical distribution 2. Habitat 3. Morphology 3. DH, IH, RH 4. Life Cycle: Infective stage and Mode of infection 5. Pathogenesis and Clinical Manifestations 6. Diagnosis 7. Treatment 8. Prevention and Control Blood, Lymphatics and Macrophage Phagocytic system Parasites Class Parasite System Nematodes Wuchereria bancrofti Lymphatic system Brugia malayi Protozoa (Hemoflagellates) Leishmania donovani Macrophage Phagocytic system of blood and viscera Protozoa (Hemofalgellates) Trypanosoma brucei spp. Blood outside RBCs and Lymphatics Trypanosoma cruzi Blood outside RBCs and intracellularly in tissue of mesenchymal origin) Protozoa (Apicomplexa) Plasmodium spp. Blood inside RBCs Babesia spp. Protozoa (Apicomplexa) Toxoplasma gondii Macrophage Phagocytic system and any nucleated cell Plasmodium spp. “Malaria”  Plasmodium spp. Disease: Malaria 10/1/2023  Distribution: - Nearly half of the world’s population is at risk of malaria (e.g., parts of Africa, Asia, the Middle East, Central and South America). - In 2020, an estimated 241 million people contracted malaria (new cases) in 85 countries. The same year 627 000 died of the disease. Four species of Plasmodium infect man causing malaria: - P. vivax: causes benign tertian malaria, prevalent in Middle East, North Africa, South America and Indian subcontinent - P. falciparum: causes malignant tertian malaria, prevalent in tropics and subtropics - P. malariae: causes quartan malaria, prevalent in patchy areas tropics and subtropics - P. ovale: causes oval tertian malaria, restricted to localized areas of West Africa  Habitat: Exo-erythrocytic (Liver), erythrocytic (RBCs). Vector: Female Anopheles. IH: Man (in whom asexual cycle occurs) Life cycle: Heteroxenous, completed in two hosts man and female Anopheles IN MAN (IH) ASEXUAL CYCLE IN FEMALE ANOPHELES (SEXUAL CYCLE) Schizogony Gametogony Sporogony - Ends in formation of - Ends in formation of - Occurs in the Midgut of female schizonts male and female Anopheles - Occurs in liver gametocytes. - Fusion of male and female (exoerythrocytic) - Occurs inside RBCs after gametes to form zygote then In RBCs several cycles of - Ends in formation of the infective (erythrocytic) erythrocytic schizogony sporozoites Life Cycle of Plasmodium I- Development in Man Infective I- Liver 40 min sporozoites female phase Anopheles Liver merozoites P.vivax P.ovale hypnozoite Trophozoite Schizont Rupture II- Blood ♂ phase Blood merozoites P.v. 3rd d P.o. 3rd d ♀ P.m. 4th d haemozoin Ring Trophozoite Schizont Rupture P.f. irreg. gametocyte II- Development in Anopheles Mosquito gut Sporozoites ♂ and ♀ gametocytes in salivary Reduction division gland ♂ and ♀ gametes Sporogony Sporocyst Oocyst exflagellation Ookinete fusion Zygote  IH DH Sporogony Infective stage: Sporozoites (bite of Female Anopheles ), Exoerythrocytic Blood stages (blood schizogny transfusion) Mode of infection: Bite of infected female Anopheles, Blood transfusion, Congenital Gametogony Use of contaminated syringes Mode of transmission: Cyclopropagtaive Erythrocytic schizogny 10/1/2023 Important points in the life cycle of Plasmodium spp. The 4 Plasmodium spp. differ in the duration of the liver cycle (8-14 days) and the number of merozoites inside the liver schizont (8000-40000). The rate of development of sporozoites inside liver cells in P. vivax and P. ovale is not synchronized some develops immediately to schizonts, while others (hypnozoites) remain dormant may be for years to develop later to schizonts. This is responsible for relapse which occurs P. vivax and P. ovale but not in P. falciparum and P. malariae due to synchronized development. Merozoites released from liver and RBCs schizonts invade RBCs but never reinvade liver cells. There are 4 erythrocytic morphological forms: young trophozoite (ring form), old trophozoite, schizont and gametocyte. Only ring form and gametocyte are present in peripheral blood film in case of P. falciparum due to sequestration of other forms in small blood vessels. In all organs, especially brain, GIT, lung, placenta, suprarenal gland, kidney, eye, etc. Important points in the life cycle of Plasmodium spp. (cont.) P. falciparum invade all ages of RBCs while P. vivax invade young RBCs. Blood stages feed on hemoglobin resulting in formation of pigments inside the parasite and fine or coarse granulation inside RBCs (stippling). The latter are known as Schuffner’s dots in P. vivax and ovale, Maurer’s dots in P. falciparum and Ziemann’s dots in P. malariae. Blood stages of different plasmodium species differ in size, shape, number of merozoites inside schizonts and in the number of parasite inside RBCs, shape and texture of malarial pigments as well as in shape, size and stippling of the RBCs. The duration of erythrocytic schizogony, followed by rupture of RBCs and release of merozoites, pigments and toxins, is 48 hours in P. vivax and P. ovale (tertian malaria), 72 hours in P. malariae (quartan malaria) and every 36-48 hours (unsynchronized) in P. falciparum. Important points in the life cycle of Plasmodium spp. (cont.) The life cycle inside vector (sporogony) differs in duration from 2- 3weeks depending on the species of the environmental conditions. Hot weather accelerate development while cold weather delay development. Not all spp. of Anopheles are efficient in transmission of malaria as the life cycle is not completed or due to preference on feeding of animals (zoophilic). The most efficient Anopheles transmitting malaria is A. gambiae in which the life cycle is completed in almost 100 % of infection beside its anthropophilic feeding. Pathogenesis: Sporozoites and liver schizonts cause no pathology. Pathogenesis is mainly due to rupture of parasitized RBCs with release of merozoites, toxins and pigments. Destruction of RBCs causes anaemia. Toxins cause the paroxysmal attacks. In falciparum malaria sequestration leading to embolic obstruction of small blood vessels in brain, kidney, GIT and suprarenal gland. In falciparum malaria, severe intravascular hemolysis may occur due to autoimmune hemolysis of RBCs leading to acute tubular necrosis, hemoglobinuria and renal failure. Symptoms: 1. Incubation period: 1-5 weeks. 2. Prodromal symptoms: headache, anorexia, muscle pain. 3. Malarial paroxysmal attacks Occurs every 3rd day (tertian) in P. vivax and P. ovale; every 4th day (quartan) in P. malariae and irregular in P. falciparum. The attacks are due to rupture of RBCs with release of toxins and pyrogens. The attacks are characterized by:  Malarial paroxysmal attacks 1. Cold stage: (0.5-1 hour): Patients feel cold, shivering, cold pale skin, temperature 38 -39 ºC 2. Hot stage: (1-6 hours): Fever, hot dry skin, patients become irritable, temp. 40 - 41 ºC. 3. Sweating stage (1-2 hours): Profuse sweating, fever subsides, patients become exhausted. Splenomegaly, hepatomegaly and jaundice. The attacks usually subsides within 3-8 weeks. Relapse and recrudescence may occur for few years. Complications of falciparum (malignant ) malaria 1. Cerebral malaria; may be fatal 2. Severe anaemia 3. Renal disease, acute tubular necrosis, nephrotic syndrome and renal failure 4. Blackwater fever 5. Dysentery 6. Algid malaria (supra-renal hemorrhage) 7. Pulmonary edema and respiratory distress syndrome (RDS) 8. Tropical splenomegaly syndrome 9. Hypoglycemia 10. Metabolic acidosis 11. Hyperkalemia 12. Hyperparasitaemia ( more than 10% to 20 %) Relapse and Recrudescence Relapse: recurrence of malaria symptoms and reappearance of the parasite in peripheral blood film due to reactivation of dormant hypnozoites in the liver cells forming schizonts that release merozoites which invade RBCs. It occurs in P. vivax and p. ovale Recrudescence: recurrence of malaria symptoms and reappearance of the parasite in peripheral blood film due to reactivation blood stages surviving in RBCs after primary infection due to inadequate treatment. It occurs in all Plasmodium spp., but mainly in falciparum and malariae. Both relapse and recrudescence may occur several years after primary infection Reinfection with malaria may occur. Reinfection in endemic areas usually results in mild or no infection due to the development of concomitant immunity (Premunition) Diagnosis: Clinical: history of living or staying even for few hours in malaria endemic area. Laboratory: - Demonstration of the parasite in Giemsa or Leishman stained thin and thick blood film (Gold standard test). Samples are best taken just before the attack. - Quantitative Buffy Coat (QBC): detection of the parasite in the buffy coat after centrifugation of anticoagulated blood in fluorescein coated capillary tube. - Detection of antigen in blood by Immunochromatographic technique (ICT).Rapid malaria diagnostic test for detection of histidine rich protein-2 - Detection of antibodies in serum by IHA, IFAT and ELISA. Important for screening blood donors - Detection of parasites' DNA by PCR: more sensitive than blood film and important for diagnosis of infection with more than one Plasmodium spp. ICT QBC Screening of blood donors for ant- Plasmodium antibodies by ELISA Plasmodium vivax diagnostic stages Schizont stage Trophozoite stage Ring stage Gametocyte stage Plasmodium falciparum Diagnostic stages Ring stage Gametocyte stage Treatment: A. Anti-malarial drugs B. Supportive therapy ▪ Bed rest ▪ Cold sponging, antipyretics and sedatives for headache ▪ Regulation of fluid intake and salt balance.  Because of the development of drug resistance multiple drugs are to be used (either in single tablets or as separate tablets) as Fansidar (Pyrimethamine-Sulfadoxine), Fansimef (Pyr-Sulf-Mef) WHO recommends artemisinin-based combination therapy (ACT). Radical cure in case of P. falciparum and P. malariae can be achieved by the use of blood schizonticidal drugs , while in P. vivax and P. ovale, combined therapy with blood and tissue schizonticidal drugs should be used to get rid of dominant hypnozoites  Chemoprophylaxis Chemoprophylaxis is to give drugs to patients travelling to endemic areas Drugs are to be given 1 day before traveling to, during stay in and for 6 weeks after leaving malaria endemic areas: Prevention and Control 1.Treatment of patients. 2.Anti-mosquitoes measure. 3.Chemoprophylaxis for patient traveling to endemic areas. 4.Screening of blood donors in endemic areas. 5.RTS,s vaccine trial Mosquitoes (Culex and Anopheles spp.) Distribution: Worldwide, being more common in warm and temperate countries but can be found in cold countries, too. Morphology: Adult: 4-10 mm; body is formed of head, thorax and abdomen Head carries a pair compound eyes, 15 segmented antennae with dense hairs in male (plumose antenna) and few hairs in female (pilose antenna) adults, and 4-segmeted maxillary palps (Mx. P). Thorax is formed of 3 segments; prothorax, mesothorax and metathorax. Each segment carries a pair of legs. Mesothorax carries a pair of wings. Abdomen is 10 segments, the last 2 are modified into male (claspers) and female (cerci) Life Cycle: Complete metamorphosis (Egg----Larva----Pupa----Adult) Bionomics: Male is vegetarian, female is blood sucker. Male dies after copulation, female live for 6-8 weeks under suitable env. conditions. In winter they may undergo hibernation. Egg, larva and pupa are aquatic stages. Pupa is non-feeding Mosquitoes (Culex and Anopheles spp.) Bionomics: Some mosquitoes prefer animal blood (Zoophilic), while other prefer human blood (anthropophilic). Culex spp. have annoying hum while Anopheles spp. have silent have. Culex and Anopheles spp. are in- and outdoors feeders, they bite mostly at night. They breed in water pools, swamps, rice field, or on any collections of water containing inorganic matters. Important Egyptian mosquitoes include: Culex pipiens, A. pharoensis, A. sergenti, A. multicolor. Diseases: Culex are the vector of bancroftian filariasis, Rift valley fever, & viral encephalitis while Anopheles spp. are the vector of malaria and Malayan filariasis. Control: - Aquatic stages: Elimination of breeding places and use of insecticides. Pupa is non feeder; it is not killed by stomach poison insecticides as Paris green - Adult stages: Wire screening, bed nets, and light traps. Use of repellants and insecticides. Sterilization of males so females are not fertilized. Genetic control to breed infertile females. Adult Anopheles Wing (spotted) with air cells Anopheles Eggs Anopheles Larva No Siphon 35  Long maxillary palps Maxillary palps long with clubbing ends Antenna with Antenna with short & sporadic hair long & dense hair Mouth parts Female Mouth parts Male Anopheles Anopheles A case of cerebral malaria A 5-year-old Kenyan boy presented to the hospital with his mother with fever and 2 attacks of seizures over the last two days. On Examination the child was very ill, temperature was 39.5°C, pulse rate was 130, blood pressure was 70/50 mmHg. He was pale with mild tinge of jaundice. The child was drowsy, tachypneic and dehydrated. While in the emergency room he fell rapidly in coma. The child was admitted to the intensive care unit. Blood chemistry revealed increased bilirubin level and hypoglycaemia. Arterial blood gases examination (ABG) revealed hypoxia and metabolic acidosis. Fundoscopic examination revealed the signs of malaria retinopathy. CBC examination revealed anaemia, Hb was 7g/dl. Giemsa stained thick and thin blood film examination revealed ring form and gametocytes of Plasmodium falciparum with more than 10 % of erythrocytes are infected. MRI brain imaging revealed signs of increased intracranial tension and other radiological evidence of cerebral malaria. In spite of correction of hypovolemia, hypoglycaemia and metabolic acidosis and management of increased intracranial tension together with antimalarial IV Quinine therapy the child died after 2 days of admission. In class assessment A) Give Reason: 1. Anopheles gambiae is the most efficient anopheline spp. transmitting malaria. 2. Malaria relapse occurs in cases of P. vivax but not in cases of P. falciparum. B) What is etiology and clinical manifestations of malarial paroxysmal attacks? C) Discuss renal complications of malaria D) Enumerate complications of falciparum malaria Babesia spp. “Babesiosis” By the end of this lecture, you should be able to: 1. List the Babesia spp. causing human infections 2. Describe life cycle in man and vector, infective stages, modes of infection, and diagnostic stages of Babesia spp. infecting man. 3. Discuss the clinical manifestations of babesiosis its complications. 4. Outline the diagnostic methods of Babesia and identify the different morphologic forms present in peripheral blood film. 5. Outline treatment and preventive measures of Babesia spp. 6. Identify the hard tick vector of Babesia spp. 7. Outline the control measures of Babesia vector.  Distribution: Babesia is a blood parasite of many mammals as cattle, sheep and dogs. Man is accidentally infected with Babesia microti, transmitted from rodents, and Babesia divergens, transmitted from cattle. They are found in many parts of the world (USA, Europe) Habitat: RBCs (intraerythrocytic) DH and Vector: Hard Tick IH: Man RH: Rodents and Cattle Morphology: - Sporozoites occurs in salivary glands of ticks, they are pear shaped. - Intraerythrocytic stages: ring form with very thin cytoplasm and large chromatin, and merozoites (2-5 µm), pyriform spherical, or ovoid. May be single or pairs or tetrads (Maltese Cross)  Life Cycle: In human and mammals: asexual cycle occurs inside RBCs. No exoerythrocytic cycle in liver as malaria. Division inside RBCs by budding, no schizonts, no pigments, no stippling of RBCs. Multiple infection with 2, 4, and up to 12 merozoites inside RBC. Formation of gametocytes occurs only in animals not in man that is why ticks don’t transmit infection from man to man. Man to man transmission occurs only by blood transfusion. In hard ticks: sexual cycle occurs in gut where, gametes form zygotes. Infections is transmitted by transovarian route to larva then trans-staidly to nymph and new adults. Sporozoites pass with saliva of tick to infect animals or man. Infective stage: Sporozoites (bite of hard ticks, adults, larva, nymph), merozoites (blood transfusion) Mode of infection: Bite of infected hard tick (transmit infection from animals as rodents and cattle to man), blood transfusion, rarely congenitally. Mode of transmission: Trans-stadial transmission Life Cycle  Clinical Manifestations (Babesiosis): Due to destruction of RBCs as malaria. In Malaria endemic areas misdiagnosis may occur 1. Babesia microti: asymptomatic or mild self-limited symptoms with low grade fever and anemia. 2. Babesia divergens: severe disease may be fatal in immunosuppressed and splenectomized patients. Characterized by high grade fever (40°C), chills, jaundice, hepatomegaly and severe anemia. Severe intravascular hemolysis (Blackwater fever), respiratory distress syndrome may occur.  Diagnosis: - Clinical: persistent fever and hemolytic anemia in endemic areas - Laboratory: - Examination of thick and thin blood film stained with Giemsa to detect ring form and merozoites. Appearance of Maltese Cross is pathognomonic. No schizonts, pigments or stippling. - Detection of Parasite’s DNA by PCR - Serology to detect antibodies Treatment: Quinine + Clindamycin or Atovaquone + Azithromycin Supportive treatment, Blood transfusion and exchange transfusion Prevention and Control: TTT of patients, Tick control measures, screening of blood donors, and TTT and vaccination of animals Ring form Maltese Cross Tetrad of merozoites Merozoites Babesia Ring form and Merozoites A case of babesiosis A 66-year-old splenectomized Portuguese man, who used to travel to several countries visiting countryside, was admitted to hospital after one week of fever, chills, abdominal pain, anorexia and nausea. On examination the patient had a slight tinge of jaundice, No enlarged lymph node. Urine examination revealed haematuria and proteinuria. Malaria was suspected, Giemsa-stained blood film revealed a high parasitaemia (30%) of Babesia parasites. The patient was treated with quinine and clindamycin. PCR examination of blood sample followed by sequencing revealed Babesia divergens. While in the hospital the patient haemoglobin dropped from 14 g/dl to 8 g/dl due to severe haemolysis. Subsequently the patient developed upper gastrointestinal bleeding and required blood transfusions. Inspite of treatment, parasitaemia persisted and he developed severe respiratory distress syndrome for which he was ventilated. Exchange blood transfusion was done. Despite treatment the patient died several weeks later from renal failure. Hard Ticks Distribution: Worldwide Morphology: Body is globular, compressed dorsoventrally and composed of 2 regions: The anterior region carries the mouth parts called the capitulum covered by teeth arranged in several rows. The posterior region carries 4 pairs of legs that end in claws. The thorax and abdomen are not clearly differentiated. The body is covered completely (in males) or partially (in females) with a scutum. There are no antennae or wings. Life Cycle: Incomplete metamorphosis (Egg----Larva----Nymph---Adult) Bionomics: Ticks are ectoparasites, they parasitize humans and animals e.g., dogs, cats, rodents, birds, cattle, horses and wild animals. Humans are accidentally parasitized. Both sexes of the adult ticks, larvae, and nymphs feed on blood. Hard ticks Bionomics: Ticks feed by cutting the host epidermis with their teeth and inserting the hypostome into the cut, thereby attaching to the host. They live for several years in absence of blood. Adult, larva and nymph feed on different host. They are permanent ectoparasites. Female lay egg under stones. Ticks are efficient vector (WHY?) Diseases: - Tick Paralysis: due to injection of neurotoxins, usually occurs in children, death may occur. - Hard ticks transmits rickettsia (American typhus, Q fever), viral (viral encephalitis), bacterial (Lyme disease), and Protozoal (Babesia spp., transmitted by Ixodes spp. of Hard ticks) diseases. Control: - Use of repellants - Wearing high boots when walking in endemic areas - Control of ticks on domestic animals by dipping the animal in emulsion of insecticides - Spraying insecticides to hiding places of ticks Ixodes Hard Tick (vector of Babesia spp.) In class assessment A) Give Reason: 1. Paris green is non suitable insecticide for controlling pupa of mosquitoes 2. Hard tick is efficient vector for disease transmission. B) What are clinical manifestations of babesiosis? C) Outline the diagnostic methods of babesiosis? D) Outline the control measures of mosquitoes References: 1. Markell and Voge's Medical Parasitology: by John , Petri (Elsevier; 10th edition). 2. Diagnostic Medical Parasitology: by Garcia (American Society for Microbiology; 6th edition, 2016). 3. Textbook of Medical Parasitology: by CK Jayaram Paniker (Jaypee; 8th edition, 2017) 4. Human Parasites: Diagnosis, treatment, prevention: By Melhorn (Springer, 2016) 5. Laboratory for Identification of Parasites of Public Health Concern, Centers for Disease Control And Prevention (http://www. cdc.gove/dpdx/ THANK YOU