This is what the Foreign & Commonwealth Office say:
"We strongly recommend that you obtain comprehensive travel and medical insurance before travelling.
Guatemalan hospitals are reluctant to give medical treatment unless they can be satisfied that the patient has medical insurance. It is therefore essential that you carry evidence of your insurance cover at all times. State-funded hospitals are on the whole under-staffed, under-funded, ill equipped, and are often unhygienic. We advise the use of private clinics where possible.
Malaria is prevalent in the low-lying areas outside Guatemala City. Anti-malarial medication is recommended.
Dengue fever is endemic in Guatemala. Affected areas include Escuintla, the Pacific Coast towns, Zacapa, and Peten. Although there is no preventive medication, mosquito repellent and clothing which covers as much skin as possible should help.
For further information on health, check the Department of Health�s website at www.dh.gov.uk"
For more info, go to:
http://www.fco.gov.uk/servlet/Front?pagename=OpenMarket%2FXc elerate%2FShowPage&c=Page&cid=1007029390590&a=KCountryAdvice &aid=1013618385965