If you have trouble finding a proper themed romper suit for an infant to wear, don't just give up on the idea because there are always workarounds. You don't need to buy a specific Halloween item at all (though it is nice) but can get creative in searching for an outfit that features this animal or it's tan color sandy brown print. I've shown a couple of alternative solutions to the left of the page.
I just love that really cute Carter's 2 piece, green and brown bodysuit with spotty lime green pants and a sweet design on top. You can make or buy pretend giraffe ears and a tail which will highlight the zoo animal theme even more. A very young infant is going to be much more comfortable in a purpose romper suit than a thick costume, look out for a sweet and charming stripy, baby suit which is simply gorgeous. Add a cute little head band with pretend soft ears made from no-sew felt - and you're good to go.
Here are some other ideas that you can buy. Also check your local auction site out because you could get a fantastic deal on a design which is either new or nearly new - especially out of the actual season. It's definitely worth a look. I hope you find just the thing!