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 . what is loa loa. loa loa is eradicated mostly from from Asian country like India, Nepal, China etc. , the presentation is for 2nd year O.A students & EHW. which shows basic....knowledge

1. EPIDEMIOLOGY OF LOA LOA
DR. VINIT KUMAR

2. EPIDEMIOLOGY OF LOA LOA

3. • Epidemiological studies have been emphasized in the western part of Africa. In
this area, the disease is considered endemic. A study conducted by the Research
Foundation in Tropical Diseases and Environment in 2002 had a sample of 1458
persons, spanning 16 different villages, and found Loa loa presence in these
villages ranging from 2.22 to 19.23% of the population. The disease was found to
be slightly more prevalent in men.

4. Onchocerciasis:
Causative agent: Onchocerca volvulus River blindness
Mode of transmission: bite of blackfly (genus Simulium), rivers and streams
Ocular findings: Microfilariae migrates: conjunctiva, cornea, anterior chamber, vitreal
humor, retina, choroid, and optic nerve
.
u/l marked inflammation  dead or dying microfilariae
anterior segment (Punctate keratitis, fluffy ‘snowflake’ corneal opacities and iritis)
posterior segment (chorioretinitis, papillitis, and optic atrophy)
granulomas
cataracts
secondary glaucoma
sclerosing keratitis (chronic, recurrent)
blindness

6. Diagnosis: clinical
analysis of skin snips
identification of the adult worm after surgical nodulectomy
serology
PCR
eosinophilia
On slit-lamp and fundoscopic examination: living microfilariae are transparent, coiled &
motileanterior chamber
dead microfilariae are opacified and straight
Inconclusive cases: evaluated by Mazzotti test: pruritus and inflammation develop in patients with
microfilariae after oral administration of a small dose of DEC.
Treatment: Ivermectin, single oral dose and repeated once or twice a year
Vector eradication & nodulectomy  prevention & treatment.
A large international program to limit onchocerciasis is currently under way in WestAfrica and is using bothvector
eradication and mass chemotherapy.

7. Loaiasis:
Causative agent: Loa loa
Mode of transmission: large, day-feeding red fly Chrysops
Ocular findings: subconjunctival migration is most common (worms move -1cm/min foreign
body sensation)
mild conjunctival injection
transient visual disturbances
periorbital swelling & pruritus
adult worms in eyelid, anterior chamber, vitreous, or retina
calabar swelling of the eyelid
uveitis
Diagnosis: clinical
blood drawn btn 10.00 a.m. & 2.00 p.m  microfilariae
serology
eosinophilia
Treatment: albendazole,ivermectin,DCE,steroids,surgical removal or cryoprobes

10. RIVER BLINDNESS
• Loa loa is the filarial nematode (roundworm) species that causes Loa loa
filariasis.
• Loa loa is commonly known as the "eye worm", as it localizes to the conjunctiva
of the eye. Loa loa is commonly found in Africa.
• It mainly inhabits rain forests in West Africa and has native origins in Ethiopia.
The disease caused by Loa loa is called loiasis and belongs to the so-called
neglected diseases.
• Oncocerca volvulus causes subcutaneous filariasis & eye worm (loa loa)

11. • Maturing larvae & adults of the "eye worm" occupy the subcutaneous layer of
the skin – the fat layer – of humans, causing disease. The L. loa adult worm which
travels under the skin can survive up to 10–15 years, causing inflammations
known as Calabar swellings. The adult worm travels under the skin, where the
female deposits the microfilariae which can develop in the host’s blood within 5
to 6 months and can survive up to 17 years.

12. • The young larvae, or microfilariae, develop in horseflies of the genus Chrysops
(deer flies, yellow flies), including the species Chrysops, which infect humans by
biting them.
• After bites from these infected flies, the microfilariae are unique in that they
travel in the peripheral blood during the day and migrate into the lungs at night.

14. Morphology
• L. loa worms have a simple body consisting of a head that lacks lips, a body, and a
blunt tail.
• Male adults range from 20 to 34 mm long and 350 to 430 μm wide.
• Female adults range from 20 to 70 mm long and can be about 425 μm wide.
• They vary in color.

15. life cycle of microfilaria / loa loa
• The human is the definitive host, in which the parasitic worms attain sexual
maturity, mate, and produce microfilariae.
• The flies serve as intermediate hosts in which the microfilariae undergo part of
their morphological development, and then are borne to the next definitive host

16. • Usually, about 5 months are needed for larvae (transferred from a fly) to
mature into adult worms, which they can only do inside the human body.
The most common display of infection is the localized allergic
inflammations called Calabar swellings that signify the migration of the
adult worm in the tissues away from the injection site by the vector. The
migration does not cause significant damage to the host and is referred to
as benign. However, these swellings can be painful, as they are mostly
found near the joints .

17. • The symptoms can appear as early as 4 months after a bite.
• These parasites have a diurnal periodicity in which they circulate in the peripheral
blood during the daytime, but migrate to vascular parts of the lungs during the
night.
• Therefore, the appearing and disappearing characteristics of this parasite can
cause recurrent swelling that can cause painful enlargements of cysts in the
connective tissue surrounding tendons.

18. RISK FACTOR
• people at the highest risk for acquiring loiasis are those who live in the rainforests
of West or Central Africa. The flies are also attracted to smoke from wood fires.
• Travelers can be infected in less than 30 days after arriving in an affected area,
although they are more likely to be infected whilst being bitten by multiple flies
over the course of many months.
• Men are more susceptible than women due to their increased exposure to the
vectors during activities such as farming, hunting, and fishing

19. DIAGNOSIS
• The main methods of diagnosis include the presence of microfilariae in the blood,
the presence of a worm in the eye, and the presence of skin swellings.
• Complete blood count can be done.
• Patients with infections have a higher number of blood cells, namely eosinophils,
as well as high IgE levels that indicate an active infection with helminth parasites.
• Due to the migration of microfilariae during the day, the accuracy of a blood test
can be increased when samples are taken between 10 am and 2 pm.
• A Giemsa stain is the most commonly used diagnostic test that uses a thick blood
smear to count the microfilariae.
• Other than blood, microfilariae can also be observed in urine & saliva samples.

22. • Adult worms found in the eye can be surgically removed with forceps after being
paralyzed with a topical anesthesia.]
• Ivermectin has become the most common antiparasitic agent used worldwide,
but can lead to residual microfilarial load when given in the management of
loiasis. Treatment with ivermectin has shown to produce severe adverse
neurological consequences in some cases.
• DEC / diethyl carbais chosen over Ivermectin because evidence supports its
ability to kill both thmazine adult worms and the microfilariae,

23. common questions
1. Define epidemiology ?
2. Explain in brief life cycle of loa loa / onchocerca ?
3. What are clinical signs & symptoms of loa loa ?
4. Explain in short laboratory diagnosis of river blindness / loa loa & management
?
5. What is toxocariasis ? Life cycle ?
6. Common parasitic eye conditions . Name only ?
7. What is toxoplasmosis ? Explain in brief life cycle ? Clinical sings & symptoms ?
Management ?