MEDICAL PARASITOLOGY & ENTOMOLOGY

1. MEDICAL PARASITOLOGY &ENTOMOLOGY LECTURER: SR. NORAZSIDA RAMLI

2. Intestinal Sporozoa Cryptosporidium parvum Isospora belli Cyclospora cayetanensis Sarcocytis species

3. General characteristics • Nonmotile • Obligate intracellular parasites • Having complex life cycle • With alternating sexual and asexual phases • Oocyst containing mature sporozoites • Sporocyst- a sac within certain oocysts containing sporozoites.

4. Cryptosporidium parvum • Oocyst: - round to slightly oval, 4-6µm, • mature oocyst: - contains 4 sporozoites surrounded by a thick double layered wall; no sporocyst are visible; dark staining granul are usually apoparent. • Schizont and gametocytes: small, 2-4µm, are produced during the life cycle, but rarely seen in human specimens. • Cause cryptosporidiosis, zoonotic transmission does occur.

6. Life cycle

7. Transmission • Occurs by ingestion of food or water contaminated with infective oocysts • Person to person contact • Distributed worldwide, in most untreated water supplies • Difficult to remove physically • Resistant to many chemicals including chlorine. • Reservoir host: cattle

8. Pathogenesis • Causes self-limited diarrhea in immunocompetent individuals • Incubation period: one to several weeks. • Symptoms: nausea, fever, vomiting, anorexia, abdominal cramps, watery diarrhea, constipation • Recovery- dependent on the immune status of the host. • Serious in infant- cause of morbidity and mortality • Immunocompromised individuals- often suffer severe, intractable diarrhea. • Patient with AIDS- becomes progressively worse, does not respond to treatmentmay cause death, respiratory tract may also be infected.

9. Laboratory diagnosis • Biopsy • Microscopic examination • Modified acid fast stain • Sheather’s sugar flotation method • Formalin fixed • Giemsa stained smears • Immunodiagnostic assay • Enzyme linked immunosorbent assay (ELISA) • Fluorescent antibody detection methods

10. Treatment • Highly active antiretroviral treatment (HAART) of HIV– for AIDS patient. • Nitazoxanide- non-immunocompromised individuals.

11. Prevention • Proper water treatment • Good sanitary practice • Treat water supplies with filtration technique, as well as chemicals • Zoonotic transmission may be prevented by reducing or eliminating contact especially of immunocompromised individuals, with animals.

12. Isospora belli • Oocyst: elliptical or oval, 25-30µm by 10-17µm • Immature oocyst: containing a single central mass. • Mature oocyst: develops 2 sporoblasts, which develop into 2 sporocysts, each containing 4 cigar-shaped sporozoites, surrounded by double layered wall.

15. Life cycle

16. Transmission • Occurs by ingestion of water or food containing infective oocysts. • Zoonotic transmission does not occur. • Unprotected sexual activities: – anal-oral sexual.

17. Pathogenesis • Infection is often asymptomatic and self-limited. • When present, symptoms include: -diarrhea -abdominal pain -Weight loss -anorexia • An increase of infection in AIDS patients has been reported in recent year.

18. Laboratory diagnosis • Similar to C. parvum.

19. Treatment • Asymptomatic individuals may not require treatment • Trimethoprim-sulfamethoxazole • Metronidazole • Tetracycline • Pyrimethamine-sulfadiazine

20. Prevention • Good personal hygiene • Good sanitary conditions • Protected homosexual contact

21. Cyclospora cayetanenis • Oocyst: spherical –similar like C. parvum but larger than – 8-10µm, contains 2 sporocysts, each containing 2 sporozoites.

24. Life cycle

25. Transmission • Occurs by ingestion of contaminated food or water.

26. Pathogenesis • Incubation period: 2 to 7 days • Clinical manifestation: • Diarrhea • Myalgia • Anorexia • Weight loss • Fatigue • Vomiting • “flu-like” symptoms

27. Laboratory diagnosis • Flotation • Microscopy examination – using phase contrast microscopy and electron microscope.

28. Treatment • Trimethoprim-sulfamethoxazole

29. Prevention • Good hygiene • Good sanitation practices • Adequate water treatment methods • Thorough washing of fruits and vegetables

30. Sarcocytis species • S. bovihominis- in cattle • S. suihominis- in pigs • Oocyst: oval, contains 2 sporocysts with 4 cigar-shaped sporozoites, 25-33µm, sporocyst is similar to C.parvum but larger, bout 9-16µm, surrounded by double-layered wall • Sarcocystis “lindemanni” is the term gien to those organisms that may potentially parasitize humans.

31. Life cycle

32. Transmisson • Occur by ingestion of improperly cooked meat (containing the sarcocyst form in muscle). • By ingestion of animal feces-contaminated food or water ( oocyst stage in stool).

33. Pathogenesis • Symptoms: -diarrhea -abdominal pain -weight loss -muscle pain may be associated with the presence of sarcocysts in human striated muscle • Most cases r asymptomatic

34. Laboratory diagnosis • Microscopy examination • Muscle biopsies  histological method

35. Treatment • No treatment for the muscle form of sarcocytis infection. • Trimethoprim – sulfamethoxazole • Pyrimethamine - sulfadiazine

36. Prevention • Adequate cooking of meat • Avoidance of contact with animal feces - Prevents infection of humans as intermediate hosts.