BLOOD, HEMATOPOIETIC, AND LYMPHATIC PARASITIC INFECTIONS.

1. BLOOD, HEMATOPOIETIC, AND LYMPHATIC PARASITIC INFECTIONS. Ira Blader Microbiology and Immunology iblader@oushc.edu

2. Plasmodium • Disease • Malaria (jungle fever) comes from latin “bad air” • 200 million infected/yr with > 1 million deaths • Epidemiology • Tropical and sub-tropical areas of Africa, Asia, and South America • 4 species of Plasmodium • Plasmodium malarie • Plasmodium vivax • Plasmodium ovale • Plasmodium falciparum - most severe form • In the US seen in travelers and immigrants Clinically and morphologically similar

3. Malaria Species Geographic Distribution • P. falciparum - Tropical and Subtropical areas of Central and South America, Africa, and Southeast Asia • P. malariae - Tropical and Subtropical areas of Central and South America, Africa, and Southeast Asia • P. ovale - Primarily in Sub-saharan Africa • P. vivax - Central and South America, India and Southeast Asia. Not found in West Africa because parasite invades the RBC via uses the Duffy blood group antigens, which is not present in West Africans.

4. Plasmodium • Transmission • Bite from the Anopheles mosquito that injects sporozoites into the blood stream. • Trans-placentally • IV drug use

5. Plasmodium Life Cycle

6. Symptoms • Incubation period • Vivax/Ovale = typically 10-17 days but could be longer due to latent exoerythrocytic liver stage “hypnozoites” • Malariae = 18-40 days • Falciparum = 8-11 days • Recurring cycle of fever, chills, and sweating due to cytokines induced by RBC waste products • Vivax/Ovale= benign tertian (48 hr) • Malariae = quartan (72 hr) • Falciparum=malignant tertian (no regular cycle)

7. Symptoms (con’t) • Cycle • Parasites lyse out of RBC’s releasing pyrogens • Chills, fever, nausea, vomiting • 20-60 min later burning fever and severe headaches lasting for several hours • Temperature drops and profuse sweating • Splenomegaly, hepatomegaly and anemia • Falciparum malaria (most severe) • Hemorrhage and necrosis in brain (cerebral malaria) and other organs • Hemoglobinuria (“blackwater fever”) • May be fatal if untreated (sub-Saharan Africa)

8. Symptoms (con’t) • It’s important to correctly diagnose the strain when prescribing chemotherapies. • Chloroquine was drug of choice to treat all strains but now this drug is useless against P. falciparum due to resistance.

9. Diagnosis • Finding infected erythrocytes on thick and thin Giemsa-stained blood smears • Identification is based on • shape and size of asexual parasites • shape and size of micro-and macrogametocytes • modifications of infected rbc’s • developmental stages in peripheral blood • presence of dots or clefts on rbc’s

10. Adapted from Principles and Practice of Infectious Diseases

11. Falciparum Malariae Ovale Vivax Early ring Late ring Early intermediate ring Late intermediate ring Presegmented Segmented • Rarely seen in blood smears • Form that infects the mosquito Macrogametocyte Microgametocyte

12. Ring stages of Plasmodium falciparum.  Note the high parasitemia and multiple infections of some cells.

13. Treatment • Vivax, Ovale, Malariae, and Choloroquine sensitive Falciparum (very rare) • Blood stages – Chloroquine • Liver stage (vivax and ovale) – Primaquine • Chloroquine Resistant Falciparum • Quinine + Doxycycline OR • Quinine + Pyrimethamine-sulfadoxine

14. Prevention • Prophylaxis • Mosquito netting or window screens • Insect repellent • Protective clothing

15. Prophylaxis for Travelers • Considerations: • Travel region • How long before trip? • Cost • Side effects, pregnancy, sensitivities CONSULT CDC GUIDE http://wwwnc.cdc.gov/travel/yellowbook/2012/chapter-3-infectious-diseases-related-to-travel/malaria.htm#1975

16. RESISTANCE TO MALARIA • IMMUNE-BASED (VACCINES) • Historically have been unsuccessful because of antigenic variation by blood stage parasites • More recent success suggest that vaccine may be possible.

17. MALARIA VACCINE Blocking the ability for sporozoites to develop into merozoites generates sterile immunity to subsequent infections All strains protect against themselves cross species protein in humans not tested

18. SO WHY ISN’T THERE A MALARIA VACCINE YET? • How does one attenuate a liver stage parasite? • Drugs • None have been identified • Would be difficult to prescribe because liver stage infections are asymptomatic. • Attenuated Vaccines • YES, irradiated sporozoites!!!! But, there is only one way to grow sporozoites for this.

19. HOW CAN ATTENUATED SPOROZOITES BE MADE Need to dissect lots and lots of mosquitoes http://www.medicaldaily.com Credit: B.Chan, The Read Group, Penn State University

20. RESISTANCE TO MALARIA • HOST GENETIC BASED RESISTANCE • Hemoglobinopathies • Sickle Cell, Thalassemia • Erythrocyte polymorphisms • Ovacytosis (elliptical RBCs), Duffy blood group • Enzymopathies • Glucose-6 phosphate dehydrogenase, pyruvate kinase • Immunogenetic • HLA, TNFa, Complement Receptor 1. RBC

21. Malaria and Sickle Cell Disease • Sickle Cell Anemia – presents in people who are homozygous for the mutated HbS Hemoglobin gene allele. Most commonly seen in Africa. Why? • Hb/HbS heterozygotes are more resistant to malaria. Thus, the mutant allele provides a fitness advantage to carriers. • HbS allele is prevalent in malaria endemic regions because it has been selected for due to its role in resistance to malaria. EVOLUTION • But sickle cell patients (HbS homozygotes) are more susceptible to malaria.

22. Babesia (spp). • Disease • Babesiosis • Epidemiology • Worldwide • Transmission • Tick bite most commonly by the deer tick Ixodesscapularis, which transmits Lyme Disease • Blood transfusion

23. Babesia Life Cycle

24. Symptoms and Pathology • Largely asymptomatic • Fever, chills, sweating, myalgias, fatigue, hepatosplenomegaly, and hemolytic anemia following incubation period of 1-4 weeks. • More severe in immunosuppressed, splenectomized, and/or elderly patients.

25. Diagnosis • Finding infected erythrocytes on thick and thin Giemsa-stained blood smears. • Intraerythrocytic Babesia are pleomorphic, non-pigmented, and can appear vacuolated. These differences are used to distinguish it from Plasmodium.

26. Babesia Babesia in a thin blood smear stained with Giemsa.  Note the intra-erythrocytic vacuolated forms (black arrows). From www.cdc.gov

27. Treatment and Prevention • Atovaquone plus azithromycin or Clindamycin plus quinine. The former is preferred due to fewer adverse side effects. • Prevention includes long clothing and covered shoes, avoiding ticks by frequently checking self and pets, use of repellent.

28. Trypanosoma brucei gambiense and rhodesiense • Disease • African sleeping sickness (African trypanosomiasis) • Epidemiology • Endemic in sub-Saharan Africa • Gambiense – West African • Rhodesiense – East African • Transmission • Bite of the tsetse fly (Glossina)

30. Parasitemia levels vary due to antigenic variation # of Parasites Time

31. Symptoms • Skin ulcer or chancre at site of bite • Intermittent fever and lymphadenopathy • Demyelinating encephalitis characterized by headache, insomnia and mood changes • Muscle tremors, slurred speech and apathy develop • Somnolence and coma followed by death due to pneumonia

32. African Sleeping Sickness

33. Diagnosis • Early during infection examine aspirates from chancre or lymph nodes for presence of parasites • Identification of trypomastigotes in blood smears. May need to examine samples from various days because of varying levels of parasitemia (antigenic variation).

35. Comparison of West African and East African Trypanosomiasis

36. Treament • Need to distinguish between presence or absence of CNS disease. • Pre CNS • Gambiense Pentamidine • Rhodesiense Suramin • Post CNS – Melarsoprol for both

37. Trypanosoma cruzi • Disease • Chagas Disease or American Trypanosomiasis • Epidemiology • Endemic to Central America and South America. Some evidence in southern USA. • Presents in USA in immigrants or blood transfusions • Transmission • Vector borne – bite of the triatome or “kissing” bug (also called reduviid bug) • Congenital • Transfusion of infected Blood

39. Symptoms • Initial bite cause small sore called Chagoma. If near eye results in swollen eyelid “Romana’s sign”. • Incubation period 4 – 20 d. Acute infection causes fevers and swollen lymph nodes • Can cause deadly encephalitis in children • Systemic infection spreads via the lymphatics and bloodstream can be accompanied by fever, lymphadenopathy and hepatosplenomegaly

40. Symptoms (con’t) • Long term chronic infection can appear to be symptomless but parasite continues to grow and infect tissues • Heart – Myocarditis (the most common complication of T. cruzi infections. • GI tract – Megacolon and megaesophagus; denervation and loss of tone of GI tract. • Long term infections with no apparent disease • Placental infections can lead to spontaneous abortions

41. Chagoma

42. Romana’s sign

43. Myocarditis

44. Megacolon and megaesophagus

45. Diagnosis • Acute Phase • Identify trypomastigote phase in blood smears • Serologies not useful • Chronic Phase • Detection of T. cruzi antibodies by complement fixation, indirect hemagglutination, immunfluoresence, and ELISA. Because of false positives, usually require 2 or 3 assays. • Identify amastigotes in tissue biopsies (not necessary for differential diagnosis) • Xenodiagnosis – microscopic or PCR examation of fecal material from triatomes fed to patient blood.

46. Trypamastigotes

47. Amastigotes

48. Treatment and Prevention • Treat acute phase with Benznidazole (only ~ 70% effective). • No treatment available for chronic phase • Prevention includes • Protection from the vector • Improved housing–Insect control, removal of thatched roofs and walls

49. Diphyllobothriumlatum(broadfish tapeworm) • Disease • Diphyllobothriasis • Epidemiology • Worldwide, endemic where raw fish are eaten • Common in cold clear lakes in Scandinavia, Russia, Japan, Canada, North Central US • Transmission • Ingestion of larvae in undercooked fish

50. Symptoms • Infection is normally asymptomatic but some may complain of weakness, nausea, diarrhea, salt craving, and abdominal cramps. • Prolonged or heavy infection may lead to megablastic anemia b/c of B12 deficiency due to parasite scavenging the vitamin.