110
Table 3.6 (continued)
Causative agent
Mode of transmission
Symptoms
Major reservoir
Required
environmental
intervention
Trachoma
Microorganisms
Water, contact with
secretion of eyes/nose/
throat of infected people
Eye infection
Crowded
unhygienic
human habitat;
water pollution;
infected people
Proper sanitation
Schistosomiasis Microorganisms
Schistosomiasis is
caused by parasitic
worms; people are
infected due to contact
with infested water
during fishing/
recreational/agricultural
activity or other reasons
Contaminated
water; infected
people
Proper excreta
management; safe
agricultural
practices; safe
water supply
Chagas disease Microorganisms
Triatomine bug
Swelling at the infected
region, fatigue, rash, fever,
body aches, headache,
eyelid swelling, nausea,
diarrhea or vomiting, loss
of appetite, enlargement of
liver or spleen, and swollen
glands
Contaminated
water/soil;
infected people
Vector control
Lymphatic
filariasis
Filarial worms
Wide range of
mosquitoes
Most cases are
symptomless; the disease
causes long-term damage
to the lymphatic system
(system of thin tubes and
nodes
distributed
throughout the body)
Vector-breeding
places (stagnant
water); infected
people
Vector control
3 Fundamentals of Biology for Environmental and Medical Professionals