Division of Public Health Services  Disease Handbook for Childcare Providers 
Bureau of Infectious Disease Control   REVISED –January 2018 
GIARDIASIS 
 
Giardiasis is an intestinal illness caused by 
Giardia lamblia, a microscopic parasite.  The 
infectious form of the parasite is passed in the 
stool of an infected individual. 
 
Who gets this disease? 
Anyone can get Giardiasis.  It is very commo n in 
childcare centers; especially those that have 
children under age three.  It spreads easily among 
these children to their caretakers and families. 
 
How is it spread? 
The most common way a person becomes 
infected with giardia in the childcare setting is  by 
the fecal -oral route.  Eating food contaminated 
with the parasite may also infect a person.  Food 
may become contaminated when the person 
preparing the food has giardiasis and has some 
infected stool on his/her hands because of poor 
hand washing habits. 
 
Additionally, a person may become infected by 
drinking water that is contaminated with the 
parasite.  Streams, ponds and springs in New 
Hampshire are frequently contaminated with 
giardiasis parasites.  Water can also be 
contaminated with giardia when sewage enters the 
drinking water supply. 
 
What are the symptoms? 
The most common symptoms of a giardia 
infection are diarrhea, abdominal pain, cramping, 
decreased appetite and excess gas.  There is 
usually no fever or vomiting.  The diarrhea may 
last up to several months and can cause significant 
weight loss. 
 
How soon do the symptoms appear? 
The symptoms appear within 5- 25 days or longer.  
The average incubation period is 1-3 weeks. 
Can a person have this disease without 
knowing it? 
Yes.  Some people may ha ve very mild infections 
that are not serious enough to cause them to go to 
a doctor.  They may not feel sick at all.  In some 
cases of giardia infection, parasites can be found 
in the stool from several days to several months 
after the symptoms have stopped. 
 
What is the treatment? 
Several drugs are effective in killing the giardia 
parasite.  Treatment is usually necessary for 
persons with diarrhea. 
 
How can the spread of this disease be 
prevented? 
1. Wash hands thoroughly after using the 
toilet and diapering a child. 
2. Wash hands thoroughly before preparing 
food. 
3. Keep children who have diarrhea at home. 
4. Staff with stool positive for giardia should 
not prepare food or feed children. 
 
Who should be excluded? 
Any person with diarrhea shall be excluded from 
food handling, from childcare agencies and from 
direct care of hospitalized or institutionalized 
patients until 48 hours after resolution of 
symptoms  
Reportable? 
Yes, giardiasis is reportable by New Hampshire 
law to the Division of Public Health Services, 
Bureau of Infectious Disease Control  at (603) 
271-4496.