> coxph <- coxph(Surv(Time, Event) ~ Treatment + Parasite, data=data)
> summary(coxph)
Call:
coxph(formula = Surv(Time, Event) ~ Treatment + Parasite, data = data)

  n= 500, number of events= 317

             coef exp(coef) se(coef)      z Pr(>|z|)
Treatment 1.03502   2.81516  0.09443 10.961  < 2e-16 ***
Parasite  0.51782   1.67836  0.11337  4.567 4.94e-06 ***
---
Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1

          exp(coef) exp(-coef) lower .95 upper .95
Treatment     2.815     0.3552     2.340     3.388
Parasite      1.678     0.5958     1.344     2.096

Concordance= 0.691  (se = 0.019 )
Rsquare= 0.227   (max possible= 0.999 )
Likelihood ratio test= 128.6  on 2 df,   p=0
Wald test            = 139.1  on 2 df,   p=0
Score (logrank) test = 151.4  on 2 df,   p=0

> cox.zph(coxph)
             rho chisq        p
Treatment  0.211 13.80 2.04e-04
Parasite  -0.124  4.75 2.93e-02
GLOBAL        NA 18.86 8.02e-05