The island has a bad reputation for malaria, due to the fact that it offers a considerable quantity of breeding places for the Anopheles claviger, the mosquito whose bite conveys the infection.
In 1557, however, a great flood caused the Tiber to change its course, so that it no longer flowed under the walls of the castle, but some half a mile farther west; and its old bed (Fiume Morto) has ever since then served as a breeding ground for the malarial mosquito (Anopheles claviger).
Here Drs Lowe and Sambon made the decisive experiments which proved that the propagation of malaria was due to the mosquito Anopheles claviger.
Immitis, which is spread by means of the mosquito Anopheles (Centrbl.
Besides Anopheles, two species of Culex, C. penicillaris and C. pipiens, are also accused of transmitting the larvae.
Anopheles clavigerwas discovered.
He further found that only mosquitoes of the genus Anopheles had these cells, and that they did not get them when fed on healthy blood.
In 1898 it was conclusively shown in Italy that if a mosquito E of the Anopheles variety bites a person suffering from malaria, and is kept long enough for the parasite to develop in the salivary gland, and is then allowed to bite a healthy person, the latter will in due time develop malaria.
These mosquitoes or gnats - the terms are synonymous - belong to the family Culicidae and the genus Anopheles, which was first classified by Meigen in 1818.
In colour Anopheles is usually brownish or slaty, but sometimes buff, and the thorax frequently has a dark stripe on each side.
The genus with which Anopheles is most likely to be confounded is Culex, which is the commonest of all mosquitoes, has a world-wide distribution, and is generally a greedy blood-sucker.
A distinctive feature is the position assumed in resting; Culex has a humpbacked attitude, while in Anopheles the proboscis, head and body are in a straight line, and in many species inclined at an angle to the wall, the tail sticking outwards.
In the female of Culex the palpi are much shorter than the proboscis; in Anopheles they are of the same length.
Anopheles is also a more slender insect, with a smaller head, narrower body and thinner legs.
The ova of Anopheles are tiny black rodshaped objects, which are deposited on the water of natural puddles, ponds, or slowly moving streams, by preference those which are well supplied with vegetation; they float, singly or attached to other objects or clustered together in patterns.
Some observers maintain that Anopheles does not "sing," like the common mosquito, and its bite is much less irritating.
Anopheles rarely bites by day, and then only in dark places.
The most effective step would obviously be the extermination of the Anopheles mosquito.
An encouraging example is afforded by the remarkable fact that malaria, which was once rife in certain districts of England, has now died out, although the Anopheles maculipennis mosquito still exists there.
Other flies act as diseasecarriers, including the mosquitoes (Anopheles), which not only carry malarial germs, but also form a secondary host for these parasites.
The old genus Anopheles (characterized by the palpi being long in both sexes) is now divided into a number of genera according to the character and shape of the scales on the different regions of the body and on the wings.
Some species of mosquitoes, such Female Anopheles costalis, Loew.
Leger, " Sur un flagelle parasite de l' Anopheles maculipennis," C. r.
The summer is propagated by the mosquito (Anopheles claviger) marks a new epoch; the most diverse theories as to its origin had hitherto been propounded, but it is now possible to combat it on a definite plan, by draining the marshes, protecting the houses by fine mosquito-proof wire netting (for Anopheles is not active by day), improving the water supply, &c., while for those who have fever, quinine (now sold cheaply by the state) is a great specific. A great improvement is already apparent; and a law carried in 1903 for the Bonifica dell' Agro Romano compels the proprietors within a radius of some 6 m.