Typhoid Fever Outbreak
(this case is fictitious)
A. What disease does she have? What are the typical clinical features and course of this disease?
She is suffering from Typhoid Fever. Typical clinical features include: Incubation time of roughly two weeks; Initial signs and symptoms include high fever (usually 40 C), continued headache, and rose colored spot (usually) around stomach. Initially there is constipation but after third week of illness diarrhea may occur.
We believe that the girl has typhoid fever which is a disease caused by Salmonella typhi which was isolated from her blood sample.
Typical signs and symptoms of this disease are: chills, high fever, headache, rose-colored spots, abdominal pain, weakness, hypotension and possible cough, vomiting and diarrhea. Some clinical diagnostic features of this bacterium include: growth of black-centered colonies on HE agar, negative urease test, no gas produced in a TSI test as well as a red slant and yellow butt in the TSI test.
The course of the disease begins with infection typically from a contaminated water or food source. The incubation period can be anywhere from one to three weeks. The bacterium collects in the small intestine and it is here that it enters the bloodstream causing the mentioned signs and symptoms. The disease usually subsides within several weeks with proper treatment and recovery is high. However, if left untreated there is a higher risk of complications. In fact, 20% of all untreated cases of typhoid fever ended up with the patient either contracting pneumonia or developing intestinal hemorrhaging that cause death in some cases.
Typhoid fever is generally treated with the antibiotic chloramphenicol. If there are no results and the bacterium is resistant towards this treatment, ampicillin can be used.
Microsoft Encarta Encyclopedia 2000 Cd-Rom
B. Describe the epidemiology of this disease. How is the disease spread? Where does it come from?
Typhoid fever is spread through the fecal-oral route both by patients with the disease and by asymptomatic carriers. It can also be shed in the urine. There are no animal reservoirs for this bacterium, meaning that only humans can transmit it among other humans. Sources of the disease include contaminated food and water supply. Most often food handlers who are asymptomatic carriers transmit it. This disease is more common in third world countries, and this is a frequent method of patient contamination. Once the person contracts the bacterium, he or she will then begin shedding it, and anyone in contact with contaminated food or water risks infection.
C. How is the disease treated? What are the prospects for recovery?
· Antibiotic treatment: ampicillin, trimethoprim-sulfamethoxazole, ciprofloxacin
· Patients usually begin to feel better after 2-3 days of beginning antibiotic treatment
· Deaths rarely occur
· Without treatment 20% die from complications due to the infection
· Typhoid fever’s danger doesn’t end when symptoms disappear: Even if symptoms seem to go away, patient (“carrier”) might still be carrying S. typhi and continue to shed it in feces
D. Our evidence suggests that the patient might have acquired this disease in the Wissahickon Creek. Assuming that this is the case, how might the etiologic agent have gotten there? Offer several reasonable hypotheses. Be specific.
There are several different hypotheses that we come up with based on the evidence gathered from the creek and the textbook. Salmonella typhi is transmitted through human feces, urine or blood. This proves that it was not from the local wildlife in the reason.
The first hypothesis is that there is a leak in a septic tank in a home in the area. This may be the sources because the septic tank carries human waste and a leak could seep through the ground and reach the creek especially with a good rain shower.
The next hypothesis is that someone who is a carrier may have urinated in the creek in the vicinity of the biostation.
A third hypothesis is based on the Mary Malone case in New York. She passed Salmonella typhi from herself to others from unclean hands. This may be the case in the class. Someone who is a carrier may have gone to the bathroom and not washed his or her hands. That student could have gone on the field trip and transmitted the bacteria to others by touching the ball during the experiment.
The fourth hypothesis is that there is a leak in the plant but the current of the creek around that area flows more than there area near the biostation where the water is more stagnant. Bacteria tend to grow in more stagnant water. Therefore the bacteria may float down stream from the effluent to the biostation where it has a better chance to grow.
The fifth hypothesis is that an old effluent may be leaking into the creek and what is leaking contains chlorine. This chlorine may wear off further down the stream therefore not many coliforms were present by the new effluent but were present further down the stream. This may show that there is a leak from the plant but growth near the plant may be slightly inhibited but growth near the biostation is more optimal.
A sixth hypothesis is that someone may have dumped a dirty diaper into the creek and the baby could be infected or a carrier of the bacteria and it was transferred into the creek.
E. Since several of her classmates have acquired the same disease, county health officials will consider an appropriate community response to halt the spread of this disease. What response would be appropriate for the communities along the Wissahickon Creek?
The first course of action would be to alert the community of the situation via all forms of mass communication. In particular, the news should be circulated on television and radio programs, and in the newspapers. In addition, flyers or emails could be distributed to warn the community of the emerging epidemic. If necessary, volunteer callers could notify the community via the telephone. The community at risk should be advised to stay out of the Wissahickon Creek.
Secondly, all of the doctors in the area should be notified so that they can look for the symptoms of typhoid fever in their patients. In addition, anyone who feels that he/she may have been in contact with the contaminated water, or feels he/she may be infected, should be tested immediately. The presence of Salmonella typhi can easily be detected through stool or blood cultures. People should be aware that they could be asymptomatic carriers. Those who believe they have the symptoms of typhoid fever should refrain from handling food.
The public should also be advised to receive a typhoid fever vaccine or booster shot. Although the vaccine is not completely effective and takes a week to work, it is best to take every precaution. It would be extremely beneficial to educate the public about the symptoms of typhoid fever. These include: high fever (103-104o F), weakness, stomach pains, headaches, loss of appetite, and a characteristic rash of flat, rose colored spots on the abdomen. Most importantly, inform the community to wash their hands frequently!