Question

Discuss the role of Ixodes scapularis and Ixodes pacificus in Lyme disease.

Answer 1

Lyme disease is caused by a spirochete namely Borrelia burgdorferi. Now, Ixodes scapularis and Ixodes pacificus serves are the hard shelled ticks which serves as the vectors for this disease. Ixodes scapularis occurs in the midwestern parts of the United States while Ixodes pacificus occurs along the western regions of the United States. The transmission of this disease occurs via the injection of the tick saliva.

The disease is classified as zoonisis; since it is transmitted from small mammals to humans. The outer surface protein of Borrelia binds to the tick receptor within the midgut of the tick. When the tick feeds , the bacteria up regulates a surface protein called OspC. Following migration to salivary glands, OspC binds with Salp15, which has immunosuppressive effects that cause infection. Neutrophils fail to develop in the human body which allows the bacteria to spread via bloodstream to joints,nervous system, where symptoms begin to occur. Tryptophan is reduced in the central nervous system, which causes various neuro disorders.

The life cycle of the ticks comprises of three stages namely larvae, nymph and adult. Larvae is hatched from the fertilised eggs followed by transformation into nymphs by spring. Humans acquire this disease from infected nymphs. Following infection, they hatch into adults which then migrate into the bloodstream. The early localised infection would be a circular outwardly expanding rash which occurs after 32 days of tick bite. Adult ticks helps in the propagation of Borrelia bacteria through the bloodstream, which results in meningitis, stiffness of the neck to inflammation of the nerve roots of the spinal cord. The later symptoms are chronic and devastating such as panic attcks, somatoform delusions etc.