Intra-ocular gnathostomiasis.

INTRA-OCULAR helminthiasis is very rare in temperate regions (Ashton, 1960) and comparatively rare in the tropics. Invasion of the human eye by Gnathostoma spinigerum is rarer still, although many cases in remote and backward areas may have gone unreported. The most recent was that reported from Burma by Ko Gyi (1960). Gnathostoma spinigerum was first recovered from a gastric tumour in the tiger by Owen in 1836 (Craig and Faust, 1951), and was later seen in similar sites in the domestic cat, wild cat, leopard, and dog, in India, Thailand, Malaya, China, Japan and Australia. Levinsen (1890) obtained an immature female specimen from a breast abscess of a native woman in Thailand. In a second case from Thailand reported by Leiper (1909), an immature male specimen was found in a cutaneous nodule. A little over sixty cases of human infestation have been reported from Thailand, India, Japan, China, Malaya, and Viet-nam (Faust, 1949a). Domestic or wild mammals being the common reservoirs of infection and man a relatively incidental host, Gnathostoma is almost always found at an immature stage in subcutaneous tissues, but Chandler (1927, 1955) twice found eggs of G. spinigerum in stools, presumably human, from Burma and East Bengal. Thailand is regarded as the most heavily infested country, but it is the impression of the writer that the organism is equally prevalent in Burma, with its similar climatic, geographical, and social conditions. The life-cycle of G. spinigerum has only recently been elucidated. According to Prommas and Daengsvang (1933) and Yoshida (1935), eggs are evacuated in the faeces of the cat, the host in which the nematode may grow to maturity. The first-stage larva, which has a rotund cephalic bulb beset with spines, hatches in water in about a week. This larva survives free in water from only 2 or 3 days unless in the meantime it is ingested by various species of Cyclops. It then penetrates into the haemal cavity of the arthropod and in a week or two becomes a. second-stage larva, which has four distinct rows of spines on the cephalic bulb as well as a functional digestive tract and two pairs of cervical glands like the mature organism. Prommas and Daengsvang (1936, 1937) discovered that a second intermediate host is required; this may be a fresh-water fish, a frog, or a snake. The adolescent Gnathostoma encapsulates in the muscles or other tissues of the host; it differs from the adult in having only four instead of eight rows of cephalic hooklets, and in this resembles the larval forms obtained by Morishita and Faust (1925) from peripheral lesions in the human host. Chandler has suggested that the full complement of cephalic hooklets is attained only after a final moult (Faust, 1949b). The specimens obtained by Leiper (1909) and Tamura (1921) had eight rows of hooklets and were practically mature in both size and structure.