Typhoid fever is most common in non-industrialized countries. Travelers to Asia, Africa, Eastern Europe, and Latin America are especially at risk. Salmonella typhi bacteria are shed in the urine or stool of infected persons, including chronic carriers. There are no known animal reservoirs for typhoid fever.
Answer:
1.
3.
4.
Explanation:
In trial A, people have no immunity so there are more chances of infection and in trial C, only 50% of people have immunity so chances of infection are less, so infection will spread faster in trial A than trial C.
If compared, trial C will have less infected people than trial A because people in trial A has no immunity and people in trial C have 50% of immunity, so only fewer people will get infected even after six point of contact.
As percentage of immune people (trial C) is 50, so there are equal chances of immunity and non-immunity. there are three reasons of infection that include source, susceptible person and transmission. source and susceptible person can be the reason of infection in some non-immune people but the transmission reason can vary. s<em>o, there is probability that three nonimmune people lie under transmission reason and are not coming in contact with infected people, medical equipment or environment, that causes infection and those three people are not getting infected.</em>
<em>Hence, the correct options are 1, 3 and 4.</em>
