*Microbiology* On 6/20/2019 student # 13 arrived at the ER with fever, minor jaundice, headache, and abdominal pain. Shortly after, several other individuals from the same educational institution were attended at other ER facilities, and clinics with similar signs and symptoms. Upon testing, it was determined the students had contracted hepatitis B. Health authorities were informed. The outbreak appeared among a group of students who met two months earlier for a weekend of wild partying. Hepatitis B, a disease transmitted by body fluids, is characterized by jaundice, weakness, abdominal pain, nausea, and fever. The County Health Department, and the local health facilities have stepped in to identify the possible source of the infection. The identification of the source of the outbreak is needed to prevent further spread. After extensive questioning of all the students involved, the following close contact incidents have been established between the exposed population. Each student has been assigned a number. The two numbers in the boxes showed the two students who had close contact. The order of the boxes recreates the sequential order of the close contact events that occurred within the two days of exposure.

Contact sequence	1st	2nd	3rd	4th	5th	6th	7th	8th
Students who had close contact	3 <-> 11	15 <-> 4	7 <-> 3	8 <-> 3	2 <-> 6	4 <-> 3	11 <-> 12	10 <-> 15

Contact sequence	9th	10th	11th	12th	13th	14th	15th
Students who had close contact	5<->1	9 <-> 8	13 <-> 8	14 <-> 7	2 <-> 15	13 <-> 12	10 <-> 7

Here is a list of the students who were infected, as evidenced by antigen and antibody testing.

3, 4, 7, 8, 9, 10, 13, 14, 12

Here is the list of uninfected students as evidenced by antigen and antibody testing.

1,2,5,6,11,15

(2 pts.) Which student appears to be the source of the outbreak?

5.- (2 pts.) Which student was the index case? What is the index case of an outbrake or epidemic?

6.- (2pts.) Create a flow chart that plots the spread of the outbreak, starting at the source. Account for each of the infected students, and when/by whom they were infected.