• An engineering college has 5 hostels, each having a separate mess.

• On a particular day between 1 am & 5 am, few students who ate from one mess were admitted in the casualty with complaints of vomiting & a few of them also developed diarrhoea.

• On enquiry, it was learnt that some of the students who ate from the same mess did not suffer.

• The food items that were served for dinner were chapathi, chicken curry, fish fry, peas paneer & coffee/tea

1. What is the probable diagnosis?

Probable diagnosis is food poisoning

Probable organism is staphylococcus aureus (short incubation period, sudden onset vomiting, diarrhoea)

2. How do you proceed to find out the incriminated food?

a)Secure complete list of people involved & their history –

questionnaire concerning the food eaten during the previous 2 days

place of consumption

time of onset of symptoms

symptoms of illness in order of occurrence

personal data & any other helpful information.

b) Information collected from all those involved is summarized as follows

c) Attack rates are calculated from the collected information

• The food item likely to be responsible for outbreak is the one, consumption of which is associated with highest attack rate

d). Laboratory investigation: to incriminate the causative agent from stool, vomit,

or remnants of food by inoculating into appropriate media

to determine the total number of bacteria

to determine the relative number of each kind of organism involved

stool samples of kitchen employees & food handlers should also be investigated

Phage typing of the organisms should be done to complete the lab investigation

Blood for antibodies: • is useful for retrospective diagnosis

e)Environmental study:

• includes inspection of the eating places, kitchens & questioning of food handlers regarding food preparation

f) Data analysis: • the data should be analysed according to descriptive

methods of time, place & person distribution

• Food specific attack rates should be calculated.

3.Why was it that some students were spared to from disease?

Some of the students may not have been affected because:

They did not eat the incriminated food, or they may have

eaten so little of it that it was insufficient to cause illness

Individual resistance also plays a role

A . Food sanitation

Meat inspection Personal hygiene Food handlers – medical

inspection Food handling techniques Sanitary improvements Health education

B. Refrigeration

Proper temperature control

Foods not eaten immediately should be kept in cold storage

Cook & eat the same day is a golden rule

C. Surveillance

4.What are the preventive measures that could be undertaken to prevent such a problem in the community