Reference no: EM132352739

The Case of the Hurricane Health Hazard. Part 3.

Three weeks after the storm, power was fully restored, and water treatment facilities were operational. Looking at the planning map, Lisa noted that most alpha-quadrant gastrointestinal disease cases self resolved within a week. Many of the patients that Keyon collected samples from tested positive for norovirus, but the four most severe cases were negative for the virus. Rapid testing suggested these four patients had developed Vibrio cholerae infections; this was confirmed by culturing patient samples and isolating the pathogen on thiosulfate-citrate-bile salts agar (TCBS). Because the causative cholera strain was non-toxigenic, the patients recovered within a few days and only needed rehydration therapy and supportive care.

Meanwhile, Keyon had transferred from his alpha-quadrant post to nursing duty on Voyager, a mobile medical bus. During the past week he was seeing new cases of gastrointestinal illness in the delta quadrant, an area with only mild storm damage. Patients from this quadrant were experiencing signs and symptoms similar to the Vibrio and norovirus patients Keyon had treated several weeks ago, yet the boiled drinking-water order had been rescinded for more than a week. Keyon and his colleagues on Voyager collected stool samples from every patient that came to the unit complaining of GI distress.

Bacterial cultures for Vibrio and PCR assays for norovirus all came back negative. Fecal immunoassays were also performed, with many showing positive results for the protozoan parasite Giardia lamblia. Microscopic analysis revealed both cysts and trophozoites in the stool samples from some patients. Because cysts are difficult to find, patients would have to give samples on at least three different occasions to "catch" the cysts for an accurate test result. Patients were given supportive therapy, and some with more severe infections received the drug metronidazole, which is also called Flagyl. It would be a long time before the city was back to normal, but the threat of major disease outbreaks was finally overcome.

The incidence of cholera in the city has been recorded for the past decade and is shown in the graph below. (Note, more cases were eventually identified than were originally discovered in the case.) The 10-year average is indicated by the dashed red line. Using the incidence data, select the epidemiology terms that accurately describe this year's outbreak. (NCLEX-HESI-TEAS style)

• Chronic
• Epidemic
• Pandemic
• Endemic

As a means to confirm diagnosis, TCBS agar (Thiosulfate-citrate-bile salts-sucrose agar) is used to grow Vibrio cholerae from patient samples The recipe for this growth media is shown below. Based on this information, which of the following statements accurately describe this media? Select all that apply. (NCLEX-HESI-TEAS style)

• This media is considered a complex agar.
• This agar is selective.
• Bromothymol blue and thymol blue contribute to this agar's use as a differential media.
• Prior to inoculation, the agar is likely yellow.

Giardia undergoes a process called encystation that requires a large energy investment. Cysts are considered the parasite's infective stage. What advantages does encystation provide for the microbe? Select all that apply.

• Cysts can resist pharmacological therapies.
• Cysts have a survival advantage in the environment.
• Cysts resist water chlorination and ultraviolet treatment.
• Cysts can tolerate low pH.