This document provides an overview of onchocerciasis (river blindness). It discusses the epidemiology, etiology, life cycle, pathogenesis, clinical features, diagnosis and treatment of the disease. Onchocerciasis is caused by the filarial nematode Onchocerca volvulus, which is transmitted by blackflies. The parasite causes skin disease and visual impairment, including blindness. It remains an important public health problem in parts of Africa and Central/South America.

1. By  EdomMuluberhan
-> May , 2017
 Black lion
onchocerciasis

2. Contents
 Introduction
 Epidemiology
 Etiology
 Life cycle of onchocerca volvulus
 Pathogenesis
 Clinical features
 Complications
 Differential diagnosis
 Diagnosis
 Teatment and Prevention

3. introduction
 Helminthes that produce cutaneous signs belong to three groups:
 nematodes (round worms)
 trematodes (flukes)
 cestodes (tapeworms)

4. nematodes
 Round worms
 No eggs they give birth larvae nematodes
Ascaridiodea Rhaditoidea Filarioida
wuchereria bugari onchocerca loa Others
strongloidea others

5. Filariasis
 The filariases are an important aspect of dermatologic medicine
 Result from infection with insect-vector-borne tissue-dwelling nematodes
 This group of nematodes is characterized by having a microfilaria stage of development,
which live in the blood stream or skin
 Depending on the species, adult filariae may live in the lymphatics, blood vessels, skin,
connective tissues, or serous membranes

6. filariasis
• W. bancrofti
• B.malayi
• B.timori
Lymphatic filariasis is mainly
caused by
• Mansonella perstanse/steptocerca
• Loa loa,
• Onchocerca volvulus
Cutaneous Filariases is mainly
caused by
• Mansonella ozzardi
Body cavity infection is mainly
by

7. Onchocerciasis
Synonyms
 Blinding filariasis
 River blindness
 Swoda- Arabic for “black” to notify LOD
 Craw-craw- west Africa
 Erysipela de la costa-in central America
 Mal morado-(Zaeir and C. America)

8. Introduction
 Onchocerciasis is a filarial disease caused by a filarial nematode Onchocerca volvulus predominantly
affecting cutaneous and ocular tissues
 It is transmitted to humans through exposure to repeated bites of infected blackflies of the genus
Similium
 Symptoms include severe itching, disfiguring skin conditions and visual impairment, including
permanent blindness
 It is the second cause of blindness due to infection, and the fourth cause of preventable blindness
 It is a major public health problem and serious obstacle to socio-economic development

9. Historical background
 In 1875, John O’Neill in Ghana first reported the presence of O. volvulus microfilariae in a case of
“craw-craw,”
 In 1890- Patrick Manson observed and identified adult worms
 In 1893- Zoologist Rudolf Leukart first describes the morphology of adult worms in subcutaneous
nodules
 In 1904- Emile Brumpt recognizes that the microfilaria come from adult worms in subcutaneous
nodules and that infection occurs near river banks
 In 1917 – Rudolf Robles published “New disease” from Guatemala associated with subcutaneous
nodules, anterior ocular (eye) lesions and dermatitis,
 In 1926- Breadablane blacklock established that O.volvulus is transmitted by flies

10. Epidemiology
 The number of infected people worldwide was
estimated in 2006 to be 37 million and more than 99%
of cases occur in 31 countries in sub Saharan Africa
 In Africa, overall,120 million people live at risk of
infection in endemic countries
 Of those infected, about 270,000 are blind and an
additional 500,000 have severe visual impairment .
 Onchocerciasis affects certain areas(~31 countries) in
tropical sub-saharan Africa,
 To a lesser extent Central and Southern America, Yemen
and Saud Arabia
 The incidence of onchocerciasis has been significantly
reduced worldwide after the launching of OCP
 OCP decrease the infected people to 15.5 million in
2015

11. cont’d
 Race:- No racial predilection, but genetic variation in the host may
explain the geographic specificity
 Socioeconomic differences :-occupation as related to exposure to black
fly bites
 Sex:- No sex predilection but men may be afflicted more often because
of farm and field occupation.
 Age;
 Children born to infected mothers may be immunotolerant
 Transplacental transmission of microfilariae may occur
 Increased age results in cumulative exposure

12. Cont’d
Mortality/Morbidity;
 Second leading infectious cause of blindness, the blindness alone reduces life expectancy
by 4-10 yrs.
Socioeconomic impact
 The socioeconomic impact of skin disease, when measured in terms of
disability-adjusted life years, is as great as the burden of blindness
 High rates of celibacy, widowhood, and divorce
 disability, and diminished agricultural productivity
 School dropout
 It is estimated that 40% of the disability-adjusted life years (DALYS) lost from
onchocerciasis occur as a result of blindness; 60% of DALYS lost occur as a
result of skin disease

13. Symptoms vary with geographic location manifesting
in two major forms;
In Savanna In rainforest;
High prevalence of blindness Cutaneous symptoms are more prevalent
Affects the anterior segment of the eye,
though the posterior eye segment can also
be affected
Ocular lesions, when present, usually involve
the posterior eye segment
Severe skin atrophy Lymphadenopathy is more common
High microfilarial load Moderate microfilarial load

14. cont’d
 This is mainly due to
 Variability in parasite strains(2 strains of O.vovulus) and their pathogenicity
 Differences of vectors and their biting proclivities
 Altered host factors associated with genetic susceptibility or host immunity
 History of co-infection by other parasites
 higher quantities of Wolbachia DNA by PCR

15. Ethiopia
 Although Comprehensive epidemiological
surveys are lacking, it is estimated that 7.3
million or 17.4% of the population of
Ethiopia are at risk of infection ,1.38 million
people affected by the disease
 Studies in different areas show that
Onchocerciasis is hypoendemic
 In the last fifty years onchocerciasis has
been spreading to previously nonendemic
regions
 In view of agricultural development projects
and resettlement from the highlands into
endemic areas in southern and north-
western parts, further spread of
onchocerciasis is expected.

16. Cont’d
 Mainly the western parts i.e from the Takazi valley in the
northwest, to the Omo valley in the southwest are affected
 Endemicity is variable ranging from 17-84%
 The main endemic focal areas are;
 Kefa-Sheka and Bench Maji zone in south west
 Pawi –Metema in North West
 The prevailing clinical picture has varying degree of skin
changes

17. Etiology
 Onchocerciasis is caused by a filarial parasite Onchocerca volvulus of the familly filaridiea
 humans are the only known reservoir although there are a number of other onchocercal
species that infect animals in the Crimean region, Illinois and Switzerland
 Black flies are the only vectors
 Has adult male and female
 Male 20-45mm
 Female 230-700mm
 They are longer than any other insect-borne filariae
 Their progeny are sheathless microfilariae occurring in two sizes, approximately200 μm and
300 μm long

18. v

19. cont’d
 Wolbachia are an endosymbiotic bacteria found in O. volvulus adults and
microfilariae that are essential for the filarial worm’s fertility and survival
 They belong to the order of Richettsials
 Depletion of Wolbachia results in disruption of embryogenesis in the
worm

20.  The disease is transmitted by black flies of the
genus Simulium
 Small(2-6mm) fly with characteristic humped
thorax and short broad wings.
 Feed by rasping or abrading the surface of skin
until pool of blood forms which they lap up..
 Their larvae and pupae develop in rapidly
flowing and well oxygenated streams and rivers

21. Cont’d

22. The most important vectors are;
 Africa and the Middle east
 S.damnosum
 Ethiopia in parts of east Africa
 Simulium damnosum, S.neavei and Simulium kaffaense
 Gilgel Ghibe area
 Principal vector is Simulium damnosum
 Simulium ethiopiense seems to have declined drastically
 Americas
 S. ochraceum, S. metallicum, S. oyapockense, S. guianense, and S. exiguum
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23. Life cycle
 Onchocerciasis is transmitted by the bite of an infected black fly
 Female black flies require a blood meal for ovulation
 Bite occur usually outdoors and during the day time
 Attracted to the host by heat and smell
 They abrade the surface of the skin until a pool of blood forms, which they lap up
 Microfilariae previously residing in the dermis are present in this blood and they penetrate the gut wall of the
insect
 Then they migrate to its thoracic muscles, where they develop into larvae
 The larvae then migrate to the proboscis
 In human host larvae enter the subcutaneous tissue through a bite wound
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24. Cont’d
 The black fly deposits infective third stage larvae into the human skin,
 adult parasites (macrofilariae) over the next 6 to 12 months
 The females live in subcutaneous or deeper intramuscular tissues
 They are encapsulated within fibrous tissue and reside in nodules close to the surface of the
skin or near joints, range from 1-60
 Adult parasites can survive for up to 15 years, and each female can produce 1000 to 3000
microfilariae(unsheathed) per day.
 Then they migrate to different parts of the body through subcutaneous, dermal and ocular
tissues, and the lymph system.

27. Pathogenesis
 Cutaneous lesions
 It is the microfilariae that cause most of the serious clinical features of onchocerciasis
 survive in humans for up to 2–3 years, and adult worms for 10–15 years
 The incubation period is usually b/n 9 months–2 years(prepatent phase)
 Mature worms are found in granulomatous nodules, deep in the dermis or subcutaneous tissues
 Microfilariae
 Microfilarial load in highly infected subjects is >100 million
 They provoke a minimal immune response while alive; when they die, they incite a clinical
inflammatory response
 Mortality is significantly associated with increasing microfilarial load

28.  Breed in fast flowing streams and rivers
 Highly oxygenated water required for maturation
of the larvae
 They tends to stay within 2 km of its breeding site
 Parous flies concentrated more by the river side, while
nulliparous flies dispersed further away from the river
side
 Wolbachia helps in transmission and infection of
mammalian host by manipulating mast cell- mediated
vasodilation
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29. Cont’d
 There is a spectrum of immune response to infection
 An immunogenetic basis for this clinical spectrum has been proposed and differing isotypic
antibody responses may play a role.
 Host immunity to microfilarial stage and wolbachia as a cause of pathology for onchocercial
keratitis and dermatitis
 The magnitude of the immune system and the clinical presentation is thought to be
influenced by the hosts genetic factors

30.  Studies on human onchocerciasis tend to classify patients into three groups.
 Generalized onchocerciasis (GEO)
 Characterized by having weak or no skin inflammation despite high parasite burdens
 Severe chronic dermatitis (sowda)
 From severe symptoms and low microfilaria and adult worm burdens
 Endemic normals (EN) or “putatively immune”
 People living in areas of endemicity do not acquire detectable patent infection despite
exposure to infective vector bites
30

31. Cont’d
 Individuals with sever onchodermatitis;-
 Cellular immune responses are stronger,Microfillarial load is minimal
 T-helper (Th) 2-type responses to O. volvulus antigen
 Increased levels of IL-5 and IL-13
 high levels of anti O. volvulus immunoglobulin G1 (IgG1) and IgG3 (isotypes involved in EN
resistance to infection).
 High Ig-E levels, pronounced eosinophila
 increased delayed-type hypersensitivity.
 Eosinophils are effector cells involved in microfilaial deaths

32.  The pathogenesis of sowda and GEO might not lie on a continuum,
 sowda being the result of a hyperreactive Th2 immune reaction to microfilaria
 Both arms(Th1 and Th2)of the immune response are restored after antimicrofilarial.
 Various mechanisms appear to be involved in the immune downregulation.
32

33.  GEO is characterized by
 weak proliferative responses to filarial antigens
 low levels of gamma interferon (IFN-)
 and increasing generalized Th2 responses with increasing severity of
pathology
 IgG4 and IgE are the prominent antibody responses
 Vital non-degenerating microfilariae are not attacked by effector cells
(granulocytes and mast cells) except after death either through natural
attrition or following microfilaricidal treatment
33

34.  Antigen-specific regulatory T cells (tr1 )
 Inducing peripheral tolerance by production of IL-10 and TGF- beta and are thought to counteract
Th2-driven effect or inflammatory responses in such individuals
 Expression of T cell-inhibiting receptor (cytotoxic t-lymphocyte associated protein 4 (CTLA-4)).
 Induce b cells to secrete IgG4
 Elevated IgG4 acts as blocking antibody to inhibit degranulation of effector cells.
 Macrophages-immune modulation
 Impaired antigen-presenting functions of dendritic.
34

35.  A state of hyporesponsiveness or partial tolerance of cell-mediated responses exists in
asymptomatic persons with high microfilarial loads
 Defects in T cell responses in human filarial infections - expression of the T cell-inhibiting
receptor, CTLA-4
 Downregulation of host immunity may be induced by O. volvulus surface molecules and
by excretory-secretory products
 omega-class glutathione transferase 3 from O. volvulus (OvGST3);-has protective role against
intracellular and enviromental reactive oxygen species

36. molecules secreted by the parasitès attributed in immune
modulation of onchocerciasis
 antioxidants
 proteases
 cytokine homologues (TGF)
 glycoproteins (ES-62),
 lipid mediators (prostaglandin E2)
36

37. Cont’d
 Free microfilariae also penetrate superficial lymphatic vessels
 It may be found in
 the urine
 tears
 sputum
 Cerebrospinal fluid (CSF)
 vaginal smears

38. Ocular lesions
 Release of Wolbachia-derived antigens from dying parasites can activate innate and adaptive TH1
immunity immune responses
 The immune activation also plays an essential role in the development of anterior segment onchocercal
eye disease in an experimental murine model
 Wolbachia bacteria mediate corneal pathology by activating Toll-like receptors on mammalian cells, which
in turn stimulate recruitment and activation of neutrophils and macrophages
 Corneal inflammation appears to occur in response to both Wolbachia and Onchocerca antigens
 Dermatologic manifestations appear to occur in response to Onchocerca antigens alone
 Though the role of Wolbachia antigens has not been definitively excluded

39. Cont’d
 The most common ocular pathology involves the cornea
 Chorioretinal disease continues to progress despite elimination of the parasite from the
eye(autoimmune phenomenon)
 Cross-reactivity has been found between O. volvulus antigen Ov39 and the antigen hr44 found in the
retinal pigment epithelium,In the optic nerve and other ocular tissues
 Transfer of Ov39-derived T cell lines have been shown to induce inflammation of the limbus, iris, and
choroid in naive rats

40. Clinical presentation
 The clincal manifestations depends on
 the chronicity of the infection
 Age of the patient
 Geographic area in which it was acquired
 The location of the infection on the skin surface
 Relative immune responsiveness(immunogenetic basis) has been proposed
 Transplacental microfillaria transmission is possible
 The disease may be detectable as early as 6 months of age

41. Clinical presentation
 Historically
 Generalized pruritis
 Papular rash
 Skin color changes
 Itchy eyes,redness or photophobia
 Weight loss
 Generalized myalgia

42. Physical examination
 In children and in the earliest cases in endemic areas, the skin has an infiltrated
appearance
 The early rash is usually seen on exposed sites, such as the shoulders and around the
pelvis
 Six different patterns of skin changes have been described in onchocerciasis
 Acute papular onchodermatitis
 Chronic papular onchodermatitis
 Lichenified onchodermatitis
 Atrophy
 Depigmentation
 Onchocercal nodules(onchocercomata)

43. Acute papular onchodermatits
 Involves the face, extrimities and trunk
 Widespread small(1-3mm) pruritic papules, vesicles and pustules lesions may present sometimes with
associated erythema and edema
 It is common in children and young adults
 Typical presentation for short term visitors
 Demonstrate immune hyperresponsiveness despite low levels of parasites

45.  In central America, young patients who are heavily infected may
develop erythema of the face or upper trunk (erisipela de la
costa)
 Older patients may have violaceous papules or plaques (mal
morado) which can lead to leonine facies
 Travelers back from West and Central Africa may have acute
pruritic and erythematous swelling of a limb known as gros bras
camerounais or onchocerciasis-associated limb swelling
 In Europeans, Zaire and central America, an acute urticarial
eruption are common early signs
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46. Chronic popular onchodermatitis
 Comprises larger(3-9mm) lichenoid
papules
 Are often symmetrically distributed
over buttocks, waist, and shoulders
 are often with post- inflammatory
hyperpigmentation & some
lichenification

47. Cont’d

48. Lichenified onchodermatitis(sowda)
 Mainly seen in teenagers and young adults
 hyperkeratotic and hyperpigmented confluent
plaques
 pruritus is severe and often asymmetrical.
 When fully developed, the lichenified itchy rash
confined to one limb or contiguous area
commonly the leg
 Gross enlargement of the regional lymph nodes is
an important feature.
 Interestingly, it is found mainly in East Africa
(Sudan, Ethiopia) and Yemen.
 associated with very low microfilarial loads; it may
also improve symptomatically over time with loss
of itching and lichenification, but increasing
microfilarial loads.

49. Skin atrophy
 In adults
 Loss of skin elasticity(from loss of dermal
elastic fibres)
 The skin becomes dry and shiny with
excessive wrinkling and has the appearance of
tissue paper
 Buttocks, waist, shoulders and upper thighs
are commonly affected
 An extreme form is known as lizard skin or
elephant skin
 May be a consequence of long-standing
onchocerciasis, not usually itchy
 It may develop after any of the patterns described
previously, or arise from apparently normal but
infected skin sites.
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50. Hanging groin
 `“Hanging groin” describes the loose, atrophic skin
sack that contains large inguinal nodes
 Seen in late-stage
 it is found mainly in East Africa (Sudan, Ethiopia) and
Yemen
 Firm, nontender lymphadenopathy is a common
finding in chronically infected onchocerciasis patients
 Then as the nodes shrink and become fibrotic, leaving
redundant folds of loose skin

51. Chronic lymphatic obstruction of the inguinal lymph may lead to elephantiasis of the genitalia

52. Depigmentation
 Patches of complete pigment loss are seen with peri-
follicular "spots" or islands of normally pigmented skin
are seen giving rise to the so-called "leopard skin"
appearance
 Not itchy
 Typically occurs on the anterior shins of elderly people
bilaterally
 inguinal regions , bony prominences the shoulders and
external genitalia may also be affected
 leopard skin is used as an indicator of the prevalence
of onchocerciasis

53. Onchocercal nodules("onchocercomata")
 Subcutaneous nodules- 0.5 to 3 cm in diameter, consist of an
outer layer of fibroblasts, which contains the parasites in an
organized, fibrinous exudate
 Asymptomatic and fixed nodules involving the deep dermis
and subcutaneous tissue
 The majority of nodules are deep (not palpable)
 They occur in crops
 They usually contain1-2 adult male and 2-3 adult female
worms
 Infections acquired in Africa tend to cause nodules over the iliac
crests and around the pelvic girdle
 Also occur on the trunk, axillae, groin, and perineum
 Infections acquired in Latin America are more commonly
associated with nodules on the head, neck, and upper
extremities
 In central and south America the scalp, is the usual site of
involvement

54. Cont’d

55.  Systemic manifestations
 Generalized musculoskeletal complaints (backache, joint pains),
 weight loss,
 Insomnia, fatigue & low self esteem
 Inguinal and femoral herniae
 Secondary bacterial infections
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56. Ocular manifestations
 Onchocerciasis may result in blindness endemic communities with rates of 5–10%
 The first ocular sign of infection is the presence of microfilariae in the eye (slit-lamp examination)
 From conjunctivae microfilariae move through the cornea into the anterior and posterior chambers of the
eye
 Other manifestations include
 Punctate keratits-common acute, transient finding, reversible. Due to dead microfilarea in the cornea
cornea
 Sclerosing keratitis- chronic full thickness fibrovascular change of the cornea
 Uveatis-flare in the absence of an accompanying cell infiltrate
 Optic atrophy-optic disc pallor can occur following an episode of optic neuritis
 Onchocoreoretinitis

57. Cont’d

58. Travelers
 A minimum stay of 12 months in endemic areas is necessary to
acquire infection
 Patients manifest with itching and/or a subtle itchy papular rash, which is often
concentrated on one limb
 There may be accompanying limb edema and swelling may also occur without any rash
 Other early manifestations include transient urticaria, arthralgia, and fever
 Chronic skin changes and eye changes are typically absent
 Symptoms develop in a median period of 18 months from the time of exposure(3 months
to 3 yrs)

59. Complications
 The major complication is visual impairment and blindness
 Nodding disease
 An unusual form of epidemic epilepsy associated with onchocerciasis
 A systematic review and meta-analysis of eight studies noted that onchocerciasis is associated with
epilepsy, with an average increase in epilepsy prevalence by 0.4 percent for each 10 percent increase in
onchocerciasis prevalence
 However study in Tanzania revealed no difference in microfilarial density(PCR) between individuals with
or without epilepsy
 Evidence indicates that Onchocerciasis is a risk factor hyposexual dwarfism

60. Cont’d
 There is little evidence that the presence of onchocerciasis affects the clinical appearances
of other diseases
 Lepromatous leprosy and widespread tinea corporis are commoner in certain patients with
onchocerciasis
 HIV co-infection;
 may affect the clinical presentation of onchocerciasis, as well as the immune response
to infection
 No effect on prevalence and on Rx
 HIV infected individuals are not at greater risk of onchocerciasis
 The burden of the skin disease is higher
 Patients should be included in mass campaign Rx

61. Differential diagnosis
Depigmentation
• Post
inflamatory
changes
• Vitiligo
• Leprsoy
Nodules
• Epidermal
inclusion cysts
APOD
• Milaria
• Insect bites
• Scabies
• Eczema
CPOD
• AD
• eczema
LOD
• Lichenified
eczema
• Lichenification
2o to chronic
scabies
Atrophy
• Senile atrophy

62. Diagnosis
 Clinical in endemic areas
 skin snip
 Ultrasound
 Serology
 Slit-lamp examination
 Mazzotii patch test
 Antigen testing

63. Skinsnip
 Gold standard
 Site for a specimen
 In early and localized light infections, the site in which the dermatitis is most marked
 Generally scapular area is the favorite site
 Central America, the best site is over the scapula or iliac crest
 Africa, shins,the pelvic girdle, buttocks, and external thigh
 Yemen, the lower calf
 A minimum of two snips should be taken
 For returned traveler, often a set of six snips are taken one from over each scapula, each iliac crest,
and each calf .
 The sensitivity of the test increases if more snips are taken
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64. • Skin snips for active microfilariae
are taken with the corneoscleral
punch or by raising a little ‘tent’ of
skin with a needle then clipping
off a small, superficial portion of
the skin with a sharp knife or
scissors
• , placed in normal saline in a
microtitre well covered with
transparent adhesive tape, or
placed under a cover slip
• Examined microscopically 1–4 h
later
• Hematoxylin and eosin staining
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65. Limitations
 It takes approximately 9 to 15 months for the worm to mature and release enough microfilariae to be
detectable by skin snip
 Skin snips are inadequate for detecting
 Early or light infection
 Expatriates and in patients with sowda
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66. ultrasonography
 Ultrasonography of subcutaneous nodules
may be used for identification of adult
worms
 Detect nonpalpable nodules
 To monitor adult worm viability after
macrofilaricidal therapy
 Onchocerciasis can also be diagnosed by
the identification of the adult worm in an
excised nodule

67. Serology
 Current serology tests use blots of finger- prick blood collected on filter
paper
 standard anti-filaria enzyme-linked immunosorbent assays (ELISA)
 Have significant cross-reactivity between filarial parasites
 Some recombinant purified antigens and Western blot techniques with
 Sensitivity of >95% and specificity of >95% but they are not routinely
available for clinical use
 Ov-16 card test
 Sensitivity of 80% specificty of 100%
 Does not distinguish b/n active and past infection
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68. Slit-lamp examination
 Prior to the examination, patients should be asked to sit forward (with the head between the
knees) for at least two minutes to improve the likelihood of visualization
 Look for wriggling microfilariae within the anterior chamber of the eye
 Punctate keratitis "snowflake opacities," is easier to see than live organisms
 Punctate keratitis represents dead microfilariae surrounded by an inflammatory infiltrate;
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69. pathology
 Histologically, onchocercal dermatitis
is characterized by a mixed
inflammatory infiltrate with a large
number of eosinophils
 Microfilariae are present within slits
between collagen bundles in the
upper dermis
 In older lesions, areas of fibrosis and
calcification may predominate
 At its severest, this is accompanied by
marked acanthosis and hyperkeratosis

70. The Mazzotti test
 Not used routinely
 It may be considered
 If onchocerciasis is suspected in the absence of findings on skin snip or slit-lamp evaluation
 It is contraindicated
 Heavily infected individuals (who will have positive skin snips) and individuals with optic nerve
disease
 The reaction may be related to Wolbachia organisms within the worms
 50 mg of diethylcarbamazine is administered orally, and a reaction consisting of edema, itching,
fever, cough, arthralgias, and mild and transient pruritic rash develops within 15 minutes
 Symptoms generally reach a peak at about 24 hours and then subside over the next 48 to 72 hours
 In some cases, severe systemic reactions can develop, including pulmonary edema, visual loss,
collapse, and death
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71. Mazzoti patch test
 topical application of 10% or 20% diethylcarbamazine to a small area of the
skin to assess for local skin reaction
 It is a delayed type hypersensitivity rxn to the dead and dying
microfilariea
 It is non-invasive, inexpensive, and more sensitive than skin snipping
 Unable to identify individuals with light infestation
 Hampered by varying degrees of sensitivity in different geographic areas
 Enzyme-linked immunosorbent assay (ELISA) is positive in 60–90% of cases

72. Antigen testing
 positive only in individuals with active infection
 Useful for the diagnosis of individual infections and for monitoring
the success of therapy
 Better than serology
 Done by dipstick test for urine or tears
 Have high sensitivity(100%)and specificity level (92%) in Cameroon

73. Treatment
 Ivermectin
 the mainstay of therapy for onchocerciasis
 is effective at killing microfilariae and in preventing their escape from gravid females
 selectively binds to glutamate-gated chloride channels and causes cell death in invertebrate
nerve and muscle cells
 must be given at regular intervals to maintain low microfilarial levels and to prevent progression
of the disease
 Tx with two doses of ivermectin, six months apart, repeated every three years
 Given orally in a single dose of 150 μg/kg (100–200 μg/kg)
 Within one week following a single dose it reduce skin microfilarial counts by 90%
 Microfilarial counts remain very low for 6 months, then rise slowly but do not reach pretreatment
levels within 1 year

74.  in mass drug administration (MDA) programmes, WHO
recommends treating onchocerciasis with ivermectin at least
once yearly for about 10 to 15 years
 The drug is well tolerated and side effects are seldom severe,and
includes;
 Pruritis
 Skin edema
 Arthralgia
 Malaise
 Fever
 Its safety in pregnancy has not been established and it is
excreted in breast milk
 Caution must also be taken when using ivermectin in regions
endemic for Loa loa , as severe central nervous system
dysfunction may arise in patients

75.  In patients with low parasite loads about 30% will not relapse after
each treatment
 If there is eye involvement, prednisone 1 mg/kg should be started
several days before treatment with ivermectin
 has no effect on adult female worm, which can survive 14 years or
longer.
 Thus, for optimal benefit, ivermectin must be given repeatedly
throughout the life span of the parasite or be combined with
doxycycline.

76. Diethylcarbamazine (DEC)
 kills the microfilariae
 It is given as follows:
 First 3 days 1 mg/kg/day
 Second 4 days 2 mg/kg/day
 Second week 4 mg/kg , three times a day
 Third week 4 mg/kg, three times a day
 Now rarely used due to mazzoti reactions
 may cause severe exacerbation of skin and eye disease, even blindness
 Collapse and death have occurred in heavily infected patients during treatment
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77. Doxycycline
 is used to kill the Wolbachia bacteria that live in adult worms
 has been shown to significantly lower microfilarial loads in the host
 be effective in sterilizing the female worms and reducing their numbers over a period of four to
six weeks
 200 mg/day for 6 weeks
 cannot be used for treatment in areas of ongoing transmission
 Patients treated with ivermectin alone have a reappearence of dermal microfilariae only 4
months after therapy
 When combined with doxycycline,leads to absence of microfilaria that lasts for 18 months
 Antibiotics such as rifampicin and azithromycin, has shown to be effective in animal models at
reducing Wolbachia both as an alternative and as an adjunct to doxycycline
 Rifampicin may prove to be an alternative to children

78. Nodulectomy
 Surgical removal of the adult worms
 lower the numbers of microfilariae entering the eye
 Ocular reactions need treatment with corticosteroid eye
drops and mydriatics
 It may reduce the burden of eye disease but it does not cure
the disease, nor reduce transmission.

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Individuals in endemic areas with high levels of ongoing transmission
• Ivermectin 150 mcg/kg orally (single dose); repeat every 3 to 6 months until
asymptomatic
Individuals outside endemic areas or in areas with low transmission
• Doxycycline 200 mg orally once daily for 6 weeks, PLUS
• Ivermectin 150 mcg/kg orally (single dose) 4 to 6 months following end of
doxycycline therapy

80. Additional treatment
 Control itching with antihistamines
 Keratolytic preparations to resolve lichenfication
 Emollients to prevent dryness of skin
 Antibiotics for secondary bacterial infection
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81. Prevention
 No vaccine to prevent onchocerciasis infection in humans is available
 The primary means of preventing onchocerciasis is through
 vector control ; larvicides at breeding sites
 Cardiocladius oliffi, a blackfly predator potential biological control agent
 mass treatment with ivermectin of the population in endemic areas.
 Ivermectin has become the mainstay of population-based programmes for the control
& elimination of onchocerciasis with striking effect
 Annual/semi annual Rx has demonstrated to prevent progression of eye disease &
improve severe skin involvement

82.  The first widespread public health initiative to control the disease was the
 Onchocerciasis Control Programme (OCP), launched in 1974, in 11 countries.
 Through the use of larvicide spraying and ivermectin(1988), the OCP eliminated onchocerciasis as a public
health problem, then ended in 2002
 OCP relieved 40 million people from infection, prevented 600,000 people from blindness
 In 1995 the African programme for onchocerciasis control (APOC) was launched
 19 countries(including Ethiopia
 Its strategy was the use of community directed treatment with ivermectine and vector control
 In 2015 more than 114 million people were treated
 closed at the end of 2015 and a new strategy was launched the elimination of neglected tropical disease in
Africa in may 2016

83.  In 1992, the Onchocerciasis Elimination Programme for the Americas,
which also relies on ivermectin, was launched
 Colombia and Ecuador were able to stop transmission in 2007 and
2009 respectively
 Pan-American health assosciation declared in july 29, 2013,
Colombia became the first country to eliminate onchocerciasis,
Ecuador in September 2014, Mexico in July 2015, Guatemala in July
2016

84. In Ethiopia
 In 1997-2001 rapid epidemiological mapping of onchocerciasis was carried out in the western part
of the country and 78 woredas were found to be endemic in SNNPR, Benshangul gumez, and
Amhara.
 Taking the total to over 16.3 million people confirmed at risk for onchocerciasis in 181 woredas
provided by FMOH and APOC
 the national onchocerciasis programme started with a community-based free distribution of
ivermectin was first launched in Sheka Zone, Southwestern Ethiopia in 2001
 The fifth annual meeting of national onchocerciasis task force was held in addis ababa, from july 1-
5,2008 and started funding from carter center, APOC, and the lions club
 Until 2013 Ethiopia onchocerciasis programme only supported MDA in meso and hyper epidemic
areas with the treatment threshold at 20%
 Addressed over 12.3 million people and 75% of the woredas endemic for onchocerciasis

86.  North gonder CDTI project was evaluated in 2011-2013 in 40 villages and no onchocerciasis infection
was found
 In 2013, Policy shift done by FMOH from onchocerciasis control to elimination
 The country is now implementing elimination strategies targeting the elimination of onchocerciasis
in all endemic woredas by 2020
 National onchoccerciasis elimination guidelines
 Providing technical guidance and mapping and impact survey protocols
 The move from annual to biannual treatments with ivermectin for all endemic communities
 Carter center, FMOH, the Ethiopian public health institute has created laboratories with PCR
analysis and microscopy

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