I was actually replying to Shenya's post because she was comparing the trop med MPH at Tulane to the Epi one at UT Houston. If you are interested in infectious diseases, an MPH in Epi also works. Its just that with Trop Med you will be focused on tropical diseases specifically (which is more relevant to global research) and will be taking more science-based classes, which would be beneficial if you have any interest in working in a lab (lab work is becoming an important part of public health especially for outbreak investigations- and people that have a science + public health background are in demand). With the epi degree you would focus more on how to research diseases among populations (such as risk factors for disease) so you will learn some applied biostats, as well as research design and methods. It just depends what aspect of infectious disease interests you and what your career goals are, but I am sure they would let you take electives in another department like Trop Med or Global Community Health.
I applied to both UT-Houston and Tulane for my PhD with the intent of focusing on infectious disease research, Actually, neither schools focus on ID, but both programs had faculty doing HIV, STIs, and Hep C research and that's why I applied. I can tell you a little bit about Tulane based on my own research and because I have friends who are currently in or alumni with MPHs. In terms of coursework in infectious disease, the Tulane Epi department has a class on outbreak investigations (this would focus more on identifying patterns among people with the disease) as well as a course onSTIs/HIV. There are very few (there are 3 I think) and they all do work in HIV research. The department specializes more in cardiovascular disease, cancer, perinatal/reproductive epi, and it seems to me that they are trying to increase their focus on genetics.
I don't know as much about Houston's program. I have a friend who got her MPH there and left for her PhD because they had only one faculty member doing ID research (that faculty members happens to be in my area of interest and that's why I applied). Their focus is more on genetics and cancer from what I hear.
Both schools have good reputations in Public Health- so I am sure you will be fine wherever you go. 🙂