From Ebola containment to terror prevention


I read this news item and I presume that it is quite legal according to international law:-
Kenya is closing its borders to travellers from Guinea, Liberia and Sierra Leone, the three countries worst hit by the Ebola outbreak, the government has announced.  Kenya Airways also announced that it would suspend its flights to Freetown and Monrovia when the government travel ban on passengers comes into effect on Wednesday.
Several European carriers have already suspended services to the Sierra Leonean and Liberian capitals, where states of emergency have been declared to try to slow the spread of the disease.
Kenyan Health Minister James Macharia said the measure was also aimed at travellers who have passed through the affected countries.  "In the interest of public health the government has decided to temporarily suspend entry into Kenya of passengers travelling from or through the three West African countries affected by Ebola, namely Sierra Leone, Guinea and Liberia," he said.
And these measures -  Quarantine, Isolation and Interment - also seem to be legal.
Of course, there are those who, despite health threats, still demand open borders and do not accept the "disease argument".  Nevertheless, the principle seems to be:
Applied to transnational infectious disease threats, the fairness of the law as an ‘‘intermediate public good’’ must be measured by an effective delivery of radically reduced disease morbidity and mortality burdens across societies in a globalized world. These dividends are the fundamentals of global health security.
If health concerns are legitimate, if the exposure of a population to a potential danger is cause enough to prevent border crossing as well as incarceration in a form of quarantine, then surely the threat from terror attacks that have a higher possibility of killing civilians is justification for what Israel deems necessary for public security vis a vis Gaza:-
Prime Minister Benjamin Netanyahu said on Sunday any deal on Gaza''s future had to meet Israel''s security needs...Netanyahu, in public remarks to his cabinet, said Hamas should not underestimate Israel''s resolve to battle on.
"Only if there is a clear response to our security needs will we agree to reach understandings," he said.
"If Hamas thinks that through continued intermittent firing it will cause us to make concessions, it is mistaken. For as long as quiet does not return, Hamas will continue to absorb very harsh strikes."
If Ebola can be dealt with as is happening in Africa, Israel''s policies to prevent the spread of terror outside of Gaza is surely properly lawful.
Any attempt to imply, and thereby impugn me, that I am suggesting
that Arabs of Gaza are either diseased or carriers of a disease
is purposely misreading this post.  
I am comparing the cases of a state''s legal right to defend itself
through the facility of closed borders.