Diphtheria is more of a personal contact disease, though.
However, factors such as inadequate healthcare delivery systems, poverty and other social factors have led to diphtheria being an endemic/epidemic in many regions of the world e.g. the former USSR, the Indian subcontinent, South East Asia and South America. Diphtheria therefore, continues to be a serious health problem within these countries and presents potential health risks to other countries (Warton et al. 2000, Journal of Infectious Diseases 2000;181:S1; Dittmann, S. et al. 2000, Journal of Infectious Diseases 2000;181:S10-S22).
The microbe
Diphtheria is caused by exotoxin-producing strains of Corynebacterium diphtheriae. The microbe is a gram-positive, club-shaped rod that appears in clusters of cells lying next to one another in X and Y shapes. The bacteria contain inclusions of phosphate that appear red when stained with methylene blue, and this property can be useful for its identification. C. diphtheriae is closely related to other corynebacteria that are part of the normal flora of humans with the major difference being the ability to produce exotoxin. All virulent strains of C. diphtheriae are lysogenized by a bacteriophage that carries the diphtheria toxin gene. In the absence of the bacteriophage, the microbe is unable to cause serious disease. Expression of the toxin gene in a patient depends on the blood iron concentration dropping to a critically low level for reasons described below. Humans are the only natural hosts for the organism.
Exotoxins suck

However you can take proper precautions
Prevention
Maintain good personal and environmental hygiene.
Maintain good indoor ventilation.
Keep hands clean and wash hands properly.
Wash hands when they are dirtied by respiratory secretions e.g. after sneezing.
Cover nose and mouth while sneezing or coughing and dispose of nasal and mouth discharge properly.
Cleanse used toys and furniture properly.
Disinfect soiled articles properly.
Here's what these little chopfcuks look like