Why is there an "El" in this sentence?
 

"El ébola no es cosa de risa"

That seems to say "The ebola is no laughing matter".

Why not "ébola no es cosa de risa"?

Thanks for any guidance...

A subject has an article in Spanish.

Don't translate the 'el' back into English where it is not required.

The article is not necessary in English when generalizing. Eg: Government, people...
In Spanish, instead, you do use articles in order to mention something general.

A pleasure.

The definite article 'el' identifies the noun ébola as 'unique' and it should be used.

Juguetes de niña ( girl's toy
Juguetes de la niña ( the toys of the girl) identifies the owner of the toy.

Juguetes de Juanita ( proper name, the article is dropped)

Just to drive home the point, the plural article 'los' should be added in front of the examples given in the previous post when the toys are the subject of the sentence.
Los juguetes de la niña ...

The term "proper name" is another way to say "proper noun." Proper nouns often have an article in front of them.

Saying that the article is not used with a person's name is generally true, but there are times when an article is needed to differentiate one 'Juan' from another. Here are just a few examples:
Existe un debate sobre si el Juan que escribió estas cartas es el mismo que redactó el Evangelio de Juan.
¡Aquel es! ¡Sí, estoy segura que es Juan! -¡Juan Sánchez! – gritó Araceli, pero el Juan que volteó resultó ser otro.
Volvía a ser el Juan que Victoria había conocido.

(By the way, I know of at least one country where they almost always use the feminine definite article in front of a woman's first name, when making a reference to her. A search on "vi a la Juanita" returns many hits, for example.)

Thank you for your response.

May I also ask...

Why is it "El" and not "Lo" or "Le" or "A"?

Ébola is feminine, but in Spanish when the first syllable is stressed or with 'tilde' we use 'El' el ëbola, el águila, etc.
We use lo to denote abstract names , lo bello, lo bueno, also as a direct object o complement, le indirect object or complement, an 'a' this preposition placed before a noun of .person, animal or personified object is a direct object.

That explains a lot! Thanks.

El ébola is a masculine noun and it takes a masculine article.

The rule you stated applies to feminine nouns that start with a stressed 'a' sound, like el agua, el águila and el hacha (but not la hache; the names of letters of the alphabet are always feminine and take the feminine article).
The plural form of these nouns take the regular plural article used with feminine nouns - las aguas, las águilas, las hachas y las haches.

El virus del Ébola.

Ébola is a name of a river en Zaire, I think the virus is masculine and Ébola the name of the river where it originated. But your statement is correct since the name of the virus is =virus del Ébola because of its origin.The name of the rivers are masculine, in Colombia, Río Cauca, Amazonas, Magdalena and río Ébola in Zaire.