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6. Parasitic diseases
Nodulectomy (surgical removal of onchocercomas)
N od ules are benig n, often d eep, and th eir ablation d oes not treat onch ocerciasis. T h us,
nod ulectom y is reserv ed for cranial nod ules (th eir proxim ity to th e eye is a risk factor
for v isual com prom ise) or nod ules w h ich are cosm etically unacceptable. I n oth er cases,
refrain from nod ulectom y. N od ulectom y is perform ed und er local anaesth esia, in an
appropriately equipped facility.
Loiasis
T h e d istribution of loiasis is linked to th at of its v ector (Chrysops) in forests or sav annah
w ith g allery forests in W est or C entral A frica (lim its W est: B enin; E ast: U g and a;
N orth :
Sud an and South : A ng ola).
Clinical features
– T h e subconjunctiv al m ig ration of an ad ult w orm is path og nom onic of Loa loa
infection.
– L ocalised subcutaneous sw elling s, allerg ic in orig in, transient (sev eral h ours or d ays), 6
painless, non- pitting , appearing anyw h ere on th e bod y, frequently th e upper
extrem ities and face, often associated w ith localised or g eneralised pruritus
(«C alabar sw elling s »).
– O nset of pruritus, in th e absence of oth er sig ns.
– Sleusbiocnu,tasnineuoouussm, adigv raantcioingof(a1ncamd u/lthwouor)m, d :isparpuprietiac,ripnaglpraabpliedrlyedw ciothrd -nloikteralicneear. Such
4
m ig ration g enerally arises follow ing treatm ent w ith d ieth ylcarbam azine, rarely
spontaneously.
Laboratory
– D etection of m icrofilariae in th e periph eral blood (th ick film , stained w ith G iem sa).
B lood specim ens sh ould b e collected b etw een 1 0 am and 5 pm . Q uantify
m icrofilaraem ia ev en if th e d iag nosis is certain, since treatm ent is d eterm ined by th e
intensity of th e parasite load .
– If th e th ick film is positiv e, look for onch ocerciasis in reg ions w h ere onch ocerciasis is
co-end em ic (m ainly in C entral A frica).
Treatment
Antiparasitic treatment
– D ieth ylcarbam azine ( D E C ) is th e only m acrofilaricid e av ailable but is contra-
ind icated in:
• P atients w ith m icrofilaraem ia > 2 0 0 0 m f/ m l (risk of sev ere enceph alopath y,
w ith
poor prog nosis).
• P atients co-infected w ith O. volvulus (risk of sev ere eye lesions).
• P reg nant w om en, infants, and patients in poor g eneral cond ition.
4 For differential diagnosis, see cutaneous larva migrans, page 155.
159
Nodulectomy (surgical removal of onchocercomas)
N od ules are benig n, often d eep, and th eir ablation d oes not treat onch ocerciasis. T h us,
nod ulectom y is reserv ed for cranial nod ules (th eir proxim ity to th e eye is a risk factor
for v isual com prom ise) or nod ules w h ich are cosm etically unacceptable. I n oth er cases,
refrain from nod ulectom y. N od ulectom y is perform ed und er local anaesth esia, in an
appropriately equipped facility.
Loiasis
T h e d istribution of loiasis is linked to th at of its v ector (Chrysops) in forests or sav annah
w ith g allery forests in W est or C entral A frica (lim its W est: B enin; E ast: U g and a;
N orth :
Sud an and South : A ng ola).
Clinical features
– T h e subconjunctiv al m ig ration of an ad ult w orm is path og nom onic of Loa loa
infection.
– L ocalised subcutaneous sw elling s, allerg ic in orig in, transient (sev eral h ours or d ays), 6
painless, non- pitting , appearing anyw h ere on th e bod y, frequently th e upper
extrem ities and face, often associated w ith localised or g eneralised pruritus
(«C alabar sw elling s »).
– O nset of pruritus, in th e absence of oth er sig ns.
– Sleusbiocnu,tasnineuoouussm, adigv raantcioingof(a1ncamd u/lthwouor)m, d :isparpuprietiac,ripnaglpraabpliedrlyedw ciothrd -nloikteralicneear. Such
4
m ig ration g enerally arises follow ing treatm ent w ith d ieth ylcarbam azine, rarely
spontaneously.
Laboratory
– D etection of m icrofilariae in th e periph eral blood (th ick film , stained w ith G iem sa).
B lood specim ens sh ould b e collected b etw een 1 0 am and 5 pm . Q uantify
m icrofilaraem ia ev en if th e d iag nosis is certain, since treatm ent is d eterm ined by th e
intensity of th e parasite load .
– If th e th ick film is positiv e, look for onch ocerciasis in reg ions w h ere onch ocerciasis is
co-end em ic (m ainly in C entral A frica).
Treatment
Antiparasitic treatment
– D ieth ylcarbam azine ( D E C ) is th e only m acrofilaricid e av ailable but is contra-
ind icated in:
• P atients w ith m icrofilaraem ia > 2 0 0 0 m f/ m l (risk of sev ere enceph alopath y,
w ith
poor prog nosis).
• P atients co-infected w ith O. volvulus (risk of sev ere eye lesions).
• P reg nant w om en, infants, and patients in poor g eneral cond ition.
4 For differential diagnosis, see cutaneous larva migrans, page 155.
159
