Scully calls Mulder, telling him that the contagion could spread into the population if the fugitives are not captured. The fugitives arrive at Elizabeth's house, where she tends to Steve in the late stages of his infection.
The passage describes a situation where Scully is concerned about the spread of a contagious disease and Mulder needs to be informed.  The fugitives are in danger and have reached Elizabeth's house where she is caring for Steve, who is suffering from an illness.