1. Field of the Invention
This invention relates to an apparatus for and a method of evaluating the movement of helminths in solution and for quantifying that movement.
2. Description of the Prior Art
The problem of infectious diseases caused by helminthic parasites is a major concern of Parasitologists, who are continually developing drugs to fight these diseases. The newly developed drugs must be tested for their effect on the helminthic parasites before the drugs can be marketed. Generally, the tests are performed on several animals having the disease, which can be a costly procedure. Sufficient amounts of the drug must be synthesized to perform these tests and, in addition, it is expensive to purchase and maintain the animals.
It is therefore desirous to perform a prescreening test of the drugs to see if they have any effect on the helminths before testing on the animals. This initial testing can be performed in vitro by removing the helminths from the host animal, such as a rat, and placing the helminths in a solution to which the drug is added. The movement of the helminths in the solution containing the drug can be observed, thereby indicating whether or not the drug has an effect on the helminthic parasites.
At present, the body movement or motility of the helminths is observed by eye. However, there are high numbers of drugs to be tested every day and visual inspection would not be practical to obtain meaningful quantitative data. Several devices are known for automatically measuring the movements of the helminths. In one such device, disclosed in The Journal of Pharmacology and Experimental Therapeutics, Vol. 185, No. 2, 177-184 and The American Journal of Tropical Medicine and Hygiene, Vol. 22, No. 6, 734-742 (1973), a light source passes light through a test cell having a solution containing the helminths and the drug to be tested. The bottom of the cell has several holes in which are connected fiber optic light guides that are also connected to photocells. The movement of the helminths will cause one or more of the fiber optic guides to be intermittently covered and uncovered thereby shutting off and turning on an amplifier connected to each photocell. The number of times the helminths cover and uncover the fiber optic guides is counted and quantified by appropriate computer interface equipment. The fiber optic device is limited since only whole worm movements can be detected and therefore cannot measure the activity of small parasitic helminths.
Another known device is disclosed in Medical and Biological Engineering and Computing, 408-418 (1978), wherein an ultrasonic Doppler effect is utilized to detect the movement of the worms. Frequency shifts caused by the moving worms are recorded and quantified. This ultrasonic measuring apparatus is an expensive, technologically complicated device making it unsuitable for widespread distribution.
The measurement of sperm motility is disclosed in U.S. Pat. No. 4,176,953 issued to Bartoov, et al. In U.S. Pat. No. 4,176,953, a light source and photoelectric cell are aligned on opposite sides of a transparent container containing the suspension of sperm cells. The variations of optical density caused by the collective motion of batches of the sperm cells is detected. The device does not sense individual sperm cells but rather examines a predetermined field of the cell suspension. Thus, the device would not be useful for obtaining an index of motility for small parasitic helminths.
Thus, there is a need for a simple, inexpensive device to obtain quantitative data of the movement of helminths to provide a motility index for studying the effect of newly developed drugs on the helminths.