Distinction between Mikrofilaria bancrofti AND Mikroloa loa.
| Dry Films, Hæmatoxylin Staining:— | ||
Mf. bancrofti. | Ml. loa. | |
| (1) In graceful curves (but only if quickly dried). | (1) Kinked. | |
| (2) Tip of tail free from nuclei. | (2) Nuclei extend to tip. | |
| (3) Column of nuclei separated by a space from the cuticle. | (3) Not so distinctly. | |
| Azur Staining:— | ||
| (4) G1 cell small, easily overlooked. | (4) G1 cell large, stains deep blue, cell protoplasm = twice width of larva, easily seen. | |
| (5) Excretory cell close to excretory pore, 2 per cent. of length. | (5) Excretory cell farther from pore, 4 per cent. of length. | |
| Vital Staining with Neutral Red:— | ||
| (6) Internal body or reserve material clearly shown. | (6) Not shown. | |
Life History.—In the stomach of the mosquito the larvæ cast their sheath in the thickened blood in one to two hours. In twenty-four hours the majority have reached the thoracic muscles, where development proceeds. They are at first immobile and of a “sausage” form (110µ by 13 µ), with a short spiky tail. In three to five days the œsophagus is formed, the larva now being 0·5 mm. long. The larva appears to moult at this time. After the gut is formed papillæ, three or four in number, appear at the tail end. In two to three weeks the larvæ are 1·5 mm. long. They now leave the thorax and reach the labium, but they may be found in various parts of the body, e.g., the legs. They bore through Dutton’s membrane and so arrive on the surface of the skin, which they rapidly enter. Their development in man is unknown, but it may be very long, as children are not infected till 4 to 5, or even 10 years old, but this may be due to unknown causes.
Development takes place in numerous mosquitoes. Anophelines: Myzomyia rossii, Pyretophorus costalis, Myzorhynchus sinensis, Myzorhynchus barbirostris, Myzorhynchus peditæniatus.
Culicines: Culex pipiens, Culex fatigans, Culex skusei, Culex gelidus, Culex sitiens, Culex albopictus, Stegomyia fasciata, Stegomyia pseudoscutellaris, Stegomyia gracilis, Stegomyia perplexa, Mansonioides uniformis, Mansonioides annulipes, Scutomyia albolineata, Tæniorhynchus domesticus.
Partial development takes place in other species.
Fig. 283.—Schematic drawings of the anatomy of Ml. loa and Mf. bancrofti combined from specimens stained in different ways. The position of the organs has not been based on the average values of a large series of specimens, but on that of a single specimen. G1, chief genital cell; G2–4, other genital cells; Ex.-C., excretory cell; Ex.-P., excretory pore; A-P., anal pore; N., nerve ring. Magnification circa 1,000. (After Fülleborn).
Pathology.—Among the conditions which Filaria bancrofti is believed to produce are lymphangitis, varicose glands, especially inguinal and epitrochlear, chyluria, chylocele, lymph scrotum, orchitis, abscess, and elephantiasis. The evidence that these so-called “filarial diseases” are produced by F. bancrofti is (1) geographical and statistical; (2) pathological. Bahr has contributed evidence of the former kind from his researches in Fiji, on which we may base the following statements:—