this is power point presentation for ophthalmic assistant student regarding basic knowledge for ocular parasites like, LOA LOA, RIVER BLINDNESS , ONCHOCERCIASIS , TOXOPLASMOSIS & TOXOCARIASIS etc. which consist basic test , epidemiology, lab investigation, culture & management .

1. Ocular parasitology
Morphology & classification of parasites
O.A II nd year
Dr. VINIT KUMAR

3. Def :
• The branch of biology or medicine concerned with the study of parasitic
organisms.
• A parasite is an organism that lives on or in a host organism and gets its food
from or at the expense of its host.
• There are three main classes of parasites that can cause disease in humans:
protozoa, helminths, and ectoparasites.

4. • Entomology is the study of insects and their relationship to humans, the
environment, and other organisms .
• a host is an organism that harbours a parasitic
• Ectoparasite & endoparasite ( Types )

14. Cestodes, Nematodes & trematodes

16. Ocular involvement is preeminent clinical feature in certain
systemic parasitic infections like
• onchocerciasis (river blindness)
• loaiasis (eye worm), and
• toxoplasmosis (retinochoroiditis).

17. Other systemic parasitic infections involving ocular structures are:
• microsporidia
• protozoa
• nematodes
• cestodes
• trematodes
• Ectoparasites

18. Ocular pathology during systemic parasitic infections may be the result of:
• direct infection
• inflammation and necrosis
• space occupying lesions
• destruction secondary to migratory worms or larvae
• antiparasitic treatment

19. The epidemiology reflects:
• habitat of the causative parasites
• habits and health status of the patient.
Source of infection determined by:
• local sanitation
• presence of a vector for transmission
• intermitent and definitive hosts
• dietary history (food and water contamination)
• travel history to endemic areas

20. Classification:
I. SYSTEMIC MICROSPORIDIAL INFECTIONS:
Microsporidiosis
II.SYSTEMIC PROTOZOAL INFECTIONS:
1. Toxoplasmosis
2. Acanthamoebic infection
3. Malaria
4. Leishmaniasis
5. Giardiasis

21. III SYSTEMIC HELMINTHIC INFECTIONS:
A.Nematodes :
1. Onchocerciasis
2. Lymphatic Filariasis
3. Loa - loa
4. Toxocariasis

22. B. Cestodes:
1. Cysticercosis
2. Echinococcosis
C. Trematodes:
1. Schistosomiasis

23. • most common eye conditions like microsporidia & ocular
toxoplasmosis …
• Details .. Clinical features , signs & symptom
• Etiological agent :

24. Microsporidiosis
Causative agent: Encephalitozoon hellem and Nosema.
Various phases: growing–dividing (schizogenic) phase,
spore-forming (sporogenic) phase,
infectious spore phase
Mode of ocular infection: direct inoculation into eye structures
dissemination systemically (in AIDS patients).
Ocular findings: limited to the conjunctiva & cornea (epithelial surfaces)
Diagnosis: corneal scrapings or biopsy specimens (spores) & serology
Treatment: oral albendazole
Historically, severe, progressive cases of ocular microsporidiosis have resulted in enucleation.

26. Toxoplasmosis
Causative agent: Toxoplasma gondii
Lifecycle: cats (definitive host)
Mode of transmission: food or water contaminated with cat faeces, transplacentally or after
leukocyte transfusion & organ transplantation (Tachyzoites transported via lymphatics to eyes)
Most commonly affected age: childhood.
Ocular presentation: commonest cause of posterior uveitis worldwide.
During quiescent, asymptomatic stage: scarred, retinal lesions on fundoscopy
Most active cases are reactivation of congenital disease.
Active ocular toxoplasmosis in normal host: u/l painless DOV.

28. Ocular examination: u/l posterior uveitis - focal area of necrotizing chorioretinitis
hypopigmented ‘punched-out’scar
vitritis (headlight in the fog)
lesions recur at distant site from the old scar or in the other eye
retinal tears & RD & RH
secondary glaucoma
optic neuritis
spill over anterior uveitis
Congenital toxoplasmosis: b/l, more severe (macula), microphthalmia, vitritis, glaucoma,
nystagmus, strabismus, and ocular palsies
Immunocompromised: b/l, multifocal and severe. Leading cause of necrotizing retinitis in
AIDS
Space-occupying lesions of the CNS: ocular palsies, nystagmus, and visual-field defects

30. Common questions (Home work)
1. What is parasitology ? What is host ? What are the different types of Host ?
2. What is entomology ?
3. What are the different types of parasites ?
4. Enumarate common eye infections that are caused by parasites ?
5. What are the stages of ocular pathology during systemic parasitic infections ?
6. Classification in brief regarding ocular parasitology ?
7. What are the types of Host ?
8. What are the general types of parasites ?
9. What is the ecological relationship between parasite & host ?
10. What is difference between Cestodes, Nematodes & trematodes ? With example .