The ætiology of the disease syndrome in wuchereria bancrofti infections

The claims of certain investigators that the presence of bacteria is necessary to the occurrence of most of the pathological changes and all the inflammatory attacks associated with filariasis are called into question on the following grounds: — 1. 1. A striking correlation has been found to exist between the presence of the insect vector of Wuchereria bancrofti and the incidence of filariasis. 2. 2. There is a close relationship between the number of persons in a community with microfilariae in the blood and the amount of clinical filariasis present. 3. 3. In parasitic infections other than filariasis extensive pathological changes occur in the tissues without apparent intervention of bacteria. 4. 4. The changes produced in lymphatic leucaemia, Hodgkin's disease, and other diseases of the lymphatic system create conditions favourable to the growth of pyogenic bacteria, yet the phenomena characteristic of filariasis do not occur in these diseases. 5. 5. There has been no consistency in bacteriological findings in filarial infection. No bacterium has been found directly associated with a series of filarial conditions which is as specific in type as are those caused by the organism of pneumonia or typhoid fever. 6. 6. Positive bacteriological findings in the majority of filarial cases have been made only in purulent material from abscesses either developed or in the process of formation. 7. 7. There is evidence that bacterial infection in filariasis, such as abscess, commonly occurs as the result of direct inoculation of the inflamed area by the finger nails of the patient. 8. 8. The pathological conditions present in filariasis indicate that the filarial worms are responsible for the disease syndrome. It is probable that the dead worms undergoing disintegration and absorption liberate or produce toxic substances which give rise to acute inflammatory changes. The reaction which they cause is believed to be allergic in character. 9. 9. The existence of hyperfilariation, on which the theory of parasite responsibility for filarial symptoms depends, has been demonstrated. 10. 10. With the existence of hyperfilariation, with worms either living or degenerated and with fibrotic changes produced by adults or their microfilariae, the obstructive phenomena of filariasis are readily explicable as due to mechanical blockage. 11. 11. Studies of a few apparently normal persons from endemic areas of filariasis suggest that in hyperendemic areas of filariasis from 90 to 100 per cent. of the people are infected with W. bancrofti.