248 REPORT OF THE HARVARD AFRICAN EXPEDITION 
siderable numbers in the skin of infected cases and also in the lymphatic 
glands. | 
A number of observers have described lesions of the skin due, they believe, 
to the larval forms of Onchocerca, such as filarial itch or craw-craw, pseudo- 
ichthyosis, xeroderma and lichenization. Montpellier and Lacroix ' in the ex- 
amination of native troops in Africa suffering with a form of itch, or craw-craw, 
constantly found microfilariae in the dermal layer of the skin and independent 
of the vascular network. They conclude that the craw-craw described by O’Neil 
in 1875 is a form of filarial itch and a dermal manifestation of onchocerciasis. 
They also noted? a constantly high increase in the eosinophile cells in the 
blood, but the total number of leucocytes was not increased. The maximum 
eosinophilia, they said, seemed to occur at each discharge of microfilaria into the 
blood. 
Ouzilleau, Laigret, and Lefrou * report that subjects infected with Onchocerca 
volvulus also have microfilariae in the dermis. They believe that the micro- 
filariae create inflammatory reactions in the skin which manifest themselves by 
pseudo-ichthyosis, elephantiasis of the genitalia, and in other parts by achromia 
and cutaneous atrophy. They found an infiltration of the connective tissues 
with mononuclear cells in the dermis, with embryos of O. volvulus always present. 
In the places where pigment was lacking, dense connective tissue was found 
which contained neither vessels, glands nor microfilaria. In the epidermis, 
general hyperkeratosis was noticed, often with infiltration of leucocytes in the 
stratum germinativum and stratum filamentosum. In the lichenized zones, 
enlarged dome-like papillae were also found. In the regions of prurigo, similar 
lesions were encountered, sometimes with vesicles which had in places completely 
destroyed the epidermis. In some areas there was complete absence of pigment 
and the horny layers were much thinner than usual. In elephantiasis-like lesions, 
parakeratosis was present, the papillary vessels being much dilated. The seba- 
ceous glands were very few in number and the sweat glands had apparently 
disappeared. However, in their opinion, craw-craw is not connected with On- 
chocerca infection and they believe the cutaneous lesions are not caused through 
pruritis but that the embryos of O. volvulus themselves create the inflammatory 
reactions. Laigret * has more recently confirmed these observations upon the 
production of cutaneous lesions in onchocerciasis, characterized by xeroderma 
and advanced pseudo-ichthyosis due to constant passage of the embryos in 
the skin. : 
Macfie and Corson ’ who examined 290 prisoners on the Gold Coast, found 
that twenty-four had lichenification of the skin and in fifteen of these filariae 
were present. However, in a further study regarding lichenification and other 
skin conditions considered to be due to infection with Onchocerca, they note that 
they have observed these lesions in the skin in which no larvae were found and 
1 Montpellier, Degouillon, and Lacroix: Bull. Soc. Path. Exot. (1920), XIII, 305, 530. 
* Montpellier, Lacroix, and Boutin: Bull. Soc. Path. Exot. (1921), XIV, 653. 
> Ouzilleau, Laigret, and Lefrou: Bull. Soc. Path. Exot. (1921), XIV, 717. 
Laigret: Bull. Soc. Path. Exot. (1929), XXII, 499. 
® Macfie and Corson: Ann. Trop. Med. and Parasit. (1916), XXII, 465. 
