Symptoms occur between one to three years after initial
infection. Early indications of onchocerciasis include fever, joint pain and
skin welts (hives). Nearly 10% of infected individuals are asymptomatic.
The skin is the principal site
of infection. Intense irritation and itching of skin occurs as the body
responds to O. volvulus antigens. This inflammation eventually
leads to the thickening and cracking of skin. Loss of elasticity occurs
due to the thickening of skinand eventually atrophy of skin and wrinkling
occurs. More severe reactions occur as infections persist.
Subcutaneous nodules (onchocercomas)
are a significant indicator of infection and appear in 30% of all cases. Nodules
develop over a 18-month span and vary in size and number. Nodule location
depends on the location of the black fly bite. In Africa the nodules are mainly
found on the lower trunk and pelvic region while in the Americas the head
and neck are the most affected regions.
Many more types of cutaneous lesions occur
regionally. Some examples of these are:
Sowda is a severe cutaneous reaction in which skin
gets dark, thick, itchy and covered with scaly papules. It was originally
seen in Yemen but can now be found in Central America, West Africa,
and the Sudan.
Man demonstrating the difference in color and appearance
of his hands due to sowda. One hand is significantly darker and thicker.
Photo courtesty of WHO/TDR/Crump
de la costa
Macular rash with edema of the face, typically on one side of the
face. Acute lesion that is found in Latin America
Reddish-blue discoloration on trunk and arms. Another acute cutaneous
lesion found in Latin America. [I]
Women with erisipela-swollen cheek and rash .
Photo courtesy of MediUAQ.
Standardized system of symptom
The following classifications of onchocerciasis symptoms were created to ensure
uniformity for data collection and studies.
Papular onchodermatitis (APOD)
Solid or speckled papular rash
with the possibility of vesicles.
Child who has the early stage skin infection.
Photo courtesy of WHO/TDR/Crump
papular onchodermatitis (CPOD)
Scattered, hyperpigmented, flat-topped
papular rash with larger diameter papules than APOD.
Women with advanced dermatitis.
Photo courtesy of WHO/APOD/TDR/Crump
Raised, hyperpigmented plaques that appear with lymphadenopathy.
with rash and spots of depigmentation.
Photo courtesy of WHO/TDR/Smyth
Wrinkling and dryness of skin. particularly noticeable in younger individuals.
Wrinkled and dry skin.
Photo courtesy of WHO/TDR/Baldry
Partial loss of pigment around hair follicles. Leopard skin is
the complete loss of pigment around the hair follicle and is usually
found on the shins. Elderly individuals are especially susceptible
to leopard skin.
Severe depigmentation of shins characteristic of leopard skin.
Photo courtesy of WHO/TDR/Ngoumou
Inflammation of the lymph nodes that results in swelling. In African
cases of onchocerciasis the affected sites are the femoral and inguinal
nodes (groin area) while in the Americas the lymph nodes of the head
and neck are affected.
Female with lymphadenitis and the beginnings of hangin groin.
Photo Courtesy of WHO/TDR/Murdoch
Skin in groin area is atrophied and inelastic,
resulting in sagginess. Possible enlarged lymph nodes. [II]
Male with hanging groin and some dermatitis.
Photo courtesy of WHO/TDR
Eye involvement occurs
during chronic onchocerciasis because of the migration and death of
microfilariae in the eye tissues. 5% of all onchocerciasis cases
result in ocular lesions. Conjuctivitis often is the first reaction
to the microfilariae. Dead microfilariae also cause corneal infections
that can result in scelerosing keratitis and vascularization. Sclerosing
keratitis is the main cause of blindness in onchocerciasis cases.
Other effects of microfilariae migration include glaucoma, iritis, iridocyclitis,
optic neuritis, and papillitis. 500,000 people are blind or have impaired
vision and 270,000 have irreversible blindness because of onchocerciasis.
An eye blinded by microfilariae.
Photo courtesy of WHO/TDR