In this thesis, two viral diseases are discussed in two separate parts, namely Zika and rabies virus. Both diseases are of military importance to prevent losing strength of manpower. As the title implies: Quis custodiet ipsos custodes? (Who guards the guardians?) , if we can protect our military personnel, then they will protect us. The general introduction starts with a history of military losses, 75% of which are caused by disease and non-battle injuries, where preventive measures can be applied to lower their number. In this thesis, for both diseases, measures are available to prevent contracting the disease. Apart from research on preventing infection by both viruses, clinical aspects are also topic of this thesis. So, we reviewed severe thrombocytopenia as a rare, but very serious complication of ZIKV infection, and, we reported two fatal cases of clinical rabies virus infected patients in our center, who deceased despite all treatment efforts, including the intravenous and intrathecal administration of monoclonal antibodies. A lot of attention is paid to preventive measures in military training and pre-deployment lessons. To avoid mosquito bites, the Ministry of Defense provides impregnated clothing, mosquito nets, and insect repellent. Military personnel are vaccinated against rabies before deployment in endemic areas, and known what actions to take after a bite. If we, medical doctors, take good care of our soldiers, they will take good care of us, as reflected in the title of this thesis: Quis costodiet ipsos custodes?, which can be freely translated from Latin into: “Who protects our protectors?�