Infectious Diseases Causes And Symptoms
                     INFECTIOUS DISEASES: 
CAUSES AND SYMPTOMS
INTRODUCTION
• INFECTIOUS DISEASES ARE DISORDERS CAUSED BY ORGANISMS SUCH AS 
BACTERIA, VIRUSES, FUNGI OR PARASITES. 
• MANY ORGANISMS LIVE IN AND ON OUR BODIES. THEY'RE NORMALLY 
HARMLESS OR EVEN HELPFUL. BUT UNDER CERTAIN CONDITIONS, SOME 
ORGANISMS MAY CAUSE DISEASE.
Source: www.mayoclinic.org
EXPOSE TO INFECTIOUS DISEASES 
• SOME INFECTIOUS DISEASES CAN BE PASSED FROM PERSON TO PERSON. 
SOME ARE TRANSMITTED BY INSECTS OR OTHER ANIMALS. AND YOU MAY 
GET OTHERS BY CONSUMING CONTAMINATED FOOD OR WATER OR BEING 
EXPOSED TO ORGANISMS IN THE ENVIRONMENT.
Source: www.mayoclinic.org
SYMPTOMS
• EACH INFECTIOUS DISEASE HAS ITS OWN SPECIFIC SIGNS AND SYMPTOMS. 
GENERAL SIGNS AND SYMPTOMS COMMON TO SEVERAL INFECTIOUS 
DISEASES INCLUDE:
• FEVER
• DIARRHEA
• FATIGUE
• MUSCLE ACHES
• COUGHING
Source: www.mayoclinic.org
WHEN TO CONSULT A DOCTOR
• SEEK MEDICAL ATTENTION IF YOU:
• ARE HAVING TROUBLE BREATHING
• HAVE BEEN COUGHING FOR MORE THAN A WEEK
• HAVE SEVERE HEADACHE WITH FEVER
• HAVE UNEXPLAINED OR PROLONGED FEVER
• HAVE SUDDEN VISION PROBLEMS
Source: www.mayoclinic.org
CAUSES
• INFECTIOUS DISEASES CAN BE CAUSED BY:
• BACTERIA: THESE ONE-CELL ORGANISMS ARE RESPONSIBLE FOR 
ILLNESSES SUCH AS STREP THROAT, URINARY TRACT INFECTIONS AND 
TUBERCULOSIS.
• VIRUSES: EVEN SMALLER THAN BACTERIA, VIRUSES CAUSE A 
MULTITUDE OF DISEASES RANGING FROM THE COMMON COLD TO 
AIDS.
Source: www.mayoclinic.org
CAUSES CONT.
• INFECTIOUS DISEASES CAN BE CAUSED BY:
• FUNGI: MANY SKIN DISEASES, SUCH AS RINGWORM AND ATHLETE'S 
FOOT, ARE CAUSED BY FUNGI. OTHER TYPES OF FUNGI CAN INFECT 
YOUR LUNGS OR NERVOUS SYSTEM.
• PARASITES. MALARIA IS CAUSED BY A TINY PARASITE THAT IS 
TRANSMITTED BY A MOSQUITO BITE. OTHER PARASITES MAY BE 
TRANSMITTED TO HUMANS FROM ANIMAL FECES.
Source: www.mayoclinic.org
DIRECT CONTACT
• PERSON TO PERSON: INFECTIOUS DISEASES COMMONLY SPREAD 
THROUGH THE DIRECT TRANSFER OF BACTERIA, VIRUSES OR OTHER 
GERMS FROM ONE PERSON TO ANOTHER. 
• ANIMAL TO PERSON: BEING BITTEN OR SCRATCHED BY AN INFECTED 
ANIMAL EVEN A PET CAN MAKE YOU SICK AND, IN EXTREME 
CIRCUMSTANCES, CAN BE FATAL. 
Source: www.mayoclinic.org
INDIRECT CONTACT
• DISEASE-CAUSING ORGANISMS ALSO CAN BE PASSED BY INDIRECT 
CONTACT. MANY GERMS CAN LINGER ON AN INANIMATE OBJECT, SUCH AS 
A TABLETOP, DOORKNOB OR FAUCET HANDLE.
Source: www.mayoclinic.org
FOOD CONTAMINATION
• DISEASE-CAUSING GERMS CAN ALSO INFECT YOU THROUGH 
CONTAMINATED FOOD AND WATER. THIS MECHANISM OF TRANSMISSION 
ALLOWS GERMS TO BE SPREAD TO MANY PEOPLE THROUGH A SINGLE 
SOURCE. 
Source: www.mayoclinic.org
RISK FACTORS
• WHILE ANYONE CAN CATCH INFECTIOUS DISEASES, YOU MAY BE MORE 
LIKELY TO GET SICK IF YOUR IMMUNE SYSTEM ISN'T WORKING PROPERLY. 
THIS MAY OCCUR IF:
• YOU'RE TAKING STEROIDS OR OTHER MEDICATIONS THAT SUPPRESS 
YOUR IMMUNE SYSTEM, SUCH AS ANTI-REJECTION DRUGS FOR A 
TRANSPLANTED ORGAN
• YOU HAVE CERTAIN TYPES OF CANCER OR OTHER DISORDERS THAT 
AFFECT YOUR IMMUNE SYSTEM
Source: www.mayoclinic.org