Medical records concerning filarial diseases in Ceylon date from the account of Davy, though there are hints as to the more obvious manifestations in the old chronicles of the country, too. A first survey was conducted in 1912/1913 concentrating on urban areas, followed by a second survey in the 1930s with emphasis on the rural parts. The results displayed a remarkable distribution pattern: Wuchereria bancrofti, the so-called "urban type", concentrated in Galle and Matara towns, whereas Brugia malayi, the "rural type", widespread along the southwest coast from Matara to Negombo, plus isolated pockets in the northwest, central north, east and south. The survey of the 1930s lead to the supposition that the occurrence of B. malayi must have something to do with the distribution of certain water plants, a suspicion later on confirmed in that Pistia stratiotes in particular--but other water plants as well--are essential for the survival of the vector (Taeniorhynchus (Mansonia) uniformis) during its early (submersed) stages of development. A determined effort to remove the water plants from tanks etc. reduced the rural type with encouraging results. At the same time, a combination of factors, in particular the war-time sojourn of masses of troops from Africa, already infected by filarial diseases, in the southwestern coastal areas triggered off an unexpected spread of the urban type out of its early "bridge-heads" in Galle and Matara towns to invade the southwest coastal areas, and, later on, supported by increased population mobility, to advance further inland too. At present, there is no remedy within sight to give some hope to come to grips with this problem as the vector, Culex pipiens fatigans, is ubiquitous and finds suitable breeding grounds practically everywhere. Research into the history of filarial diseases in Ceylon points as far as B. malayi is concerned, to an invasion by a Malayan army under the Kalinga kings during the days of close relations between Ceylon and southeast Asia, i.e. during the 12th and 13th centuries, and as far as W. bancrofti is concerned, a Chinese army, invading the southern coast in the early 15th century, is made responsible. Filarial diseases in Ceylon present a particular interesting case of geomedical research; but inspite of encouraging results in fighting the rural type, i.e. B. malayi, the urban type, W. bancrofti, seems to remain a problem of public health in the island for the forseeable future.
Biomed Res Int,
Current technologies have become a source of omnipresent electromagnetic pollution from generated electromagnetic fields and resulting electromagnetic radiation. In many cases this pollution is much stronger than any natural sources of electromagnetic fields or radiation. The harm caused by this pollution is still open to question since there is no clear and definitive evidence of its negative influence on humans. This is despite the fact that extremely low frequency electromagnetic fields were classified as potentially carcinogenic. For these reasons, in recent decades a significant growth can be observed in scientific research in order to understand the influence of electromagnetic radiation on living organisms. However, for this type of research the appropriate selection of relevant model organisms is of great importance. It should be noted here that the great majority of scientific research papers published in this field concerned various tests performed on mammals, practically neglecting lower organisms. In that context the objective of this paper is to systematise our knowledge in this area, in which the influence of electromagnetic radiation on lower organisms was investigated, including bacteria, E. coli and B. subtilis, nematode, Caenorhabditis elegans, land snail, Helix pomatia, common fruit fly, Drosophila melanogaster, and clawed frog, Xenopus laevis.