"Treat" a Bug with Toxic Blood
Most successful vaccines and drugs rely on protecting humans or animals by blocking certain bacteria from growing in their systems. But a new theory actually hopes to take stopping infectious diseases such as West Nile virus and Malaria to the next level by disabling insects from transmitting these viruses.
Researchers say that vaccines and drugs might be used to prematurely kill ticks, sand flies and mosquitoes, known as disease vectors. These are the insects responsible for most deaths world wide.
The idea is to make blood meals from humans lethal to mosquitoes so they die before they can transmit a disease. Called endectocides, these vaccines could be administered to mammals (including potentially, humans). When the pest feeds on the blood it dies. Endectocides are currently mass administered to human populations to control the worm parasites that cause river blindness and are widely used in animals for worm control.
Endectocides are already in use to control horn and face flies in cattle. Horn flies can suck enough blood to actually cause anemia in cows, while face flies irritate the mucus membranes resulting in pinkeye in the cattle. Sprays and rubs have been developed which contain both insecticides and endectocides to control this problem. Instead of thousands of flies bothering each animal, the number can be reduced to almost zero.
A vaccine against ticks is in early development for cattle, whose growth is greatly affected by tick-borne diseases. The University of Oklahoma is working on a vaccine to target tick-protective genes, so when ticks feed on immunized cattle, the vaccine antibodies interfere directly with the biology of the tick and its feeding pattern which results in reduced tick populations. The vaccine model being developed for cattle, which is called a dual target vaccine approach because both ticks and tick-borne pathogens are targeted, will likely be applicable to other ticks and the bacteria that they transmit.
Advantages are that these control measures are more targeted than environmental spraying of insecticides; proper application would kill older frequently-biting insects and interrupt disease transmission; resistance would be slower to develop; and there may be little cross-resistance from agricultural applications.
Research has not progressed to the point of experiments or trials on humans, but the methodology is promising for protection from diseases with an insect or arachnid disease vector. This includes such problematic illnesses as West Nile Virus, Lyme Disease and Malaria.