Manipulate[Module[{alpha = 1,

uv = 5*10^10, [Alpha] = 1, a = 1, gammay = 1,
ud = 1*10^6,
n = 3500,
s = 0,
[Beta] = 0.00341,
r = 0.385,
[Kappa] = 0.000001,
rho = 1,
sigmay = 0.9, eqns, sol, plot1},

eqns = {x'[t] ==
 r*x[t] - [Kappa]*((x[t]*z[t])/(
    x[t] + y[t] + z[t] + d[t])) - ([Beta]*v[t]*x[t])/(
  x[t] + y[t] + z[t] + d[t]),
y'[t] ==
 s*y[t] + ([Beta]*v[t]*x[t])/(x[t] + y[t] + z[t] + d[t]) -
  alpha*y[t] - [Kappa]*(y[t]*z[t])/(x[t] + y[t] + z[t] + d[t]),
v'[t] ==
 n*alpha*y[t] - deltav*v[t] + Piecewise[{{1*10^6, 3 <= t <= 5}}],
d'[t] ==
 sigmay*y[t] - deltad*d[t] + Piecewise[{{5*10^10, 0 <= t <= 2}}],
z'[t] == rho*d[t - [Tau]] - deltaz*z[t], x[0] == 200, y[0] == 0,
v[0] == 0, d[t /; t <= 0] == 1, z[0] == 0};
sol = Quiet@NDSolve[eqns, {x, y, v, d, z}, {t, [Tau], 50}];

plot1 =
ParametricPlot[
Evaluate[{x[t], y[t]} /. sol], {t, [Tau], 50}]], {{[Tau], 1}, 0,
2}]