in this topic, we are going to discuss what is Communicable disease and their different types.

1. COMMUNICABLE DISEASES
LEC 2

2. INTESTINAL INFECTIONS
DIARRHEA
• Acute diarrhea is passage of loose stools with recent change in consistency and
frequency usually > 3 per day.
• Persistent diarrhea is that which lasts for 2 weeks.
• Dysentery is diarrhea with blood.
• Host
• Diarrhea affects predominantly children of 6 months – 2 years, especially those
who are malnourished.
• Like most water borne infection, diarrhea flares up in warm and rainy seasons.
• Faulty breastfeeding and insanitary complementary feeding are mostly
responsible for such seasonal outbreak.

3. Control
• Controlling the reservoir
• Usually cases are the only reservoirs. Appropriate case management (early diagnosis,
notification, isolation and treatment) should follow quickly. Three principles of diarrheal
management are,
1. Oral rehydration therapy
2. Correct feeding practice during illness
3. Avoid unnecessary antimicrobial drugs.
• Break the chain of transmission
Establishing a sanitation barrier between feces and water.
• Protect the host
• Health promotion. Better mother and child care in the form of
1. Improved nutrition during prenatal and postnatal period
2. Exclusive breastfeeding
3. Appropriate complementary feeding
4. Supplementary nutrition.

4. Plan A: oral rehydration with home available fluids
• Plan A was devised to treat diarrhea with no dehydration totally at
home.
• PREVENT DEHYDRATION. If child vomits, gives small sips frequently.
• PREVENT MALNUTRITION. Give plenty of food. Continue
breastfeeding wherever applies. If the child is taking solid food, give
cereals, pulses, vegetable, and bananas (for K+ ions).
• PREVENT PROGRESSION: Watch for signs of some or severe
dehydration and give ORS if it develops.

5. Plan B: ORS
• Plan B applies for patients with some dehydration. They should ideally be treated
in Diarrhea Treatment and Training Centers (DTTC) where they are temporarily
admitted, treated for the duration of their illness and discharged quickly.
• CORRECT DEHYDRATION. Intensely feeding ORS in 1st 4 hours; amount of ORS in
ml patient’s weight in grams x 0.075.
• After 4 hours, assess again and recategorize.
• If the condition remains same after 4 hours of ORS → continue for another 4
hours
• → if it improves, continue ORS at maintenance dose (plan A) after each stool;
• If it shows no improvement however, switch to plan C.

6. Plan C: IV rehydration
• Indications
• Severe dehydration
• Shock
• Plan B failure
• Vomiting continuing > 3 hours
• Failure to drink ORS
• EMERGENCY REHYDRATION with 100ml/kg fluid is the rule.
• Use either,
1. Ringer lactate (the lactate yields bicarbonate which corrects
acidosis)
2. Normal saline.

7. Cholera
• Cholera is the prototype of diarrheal diseases, and often the two terms
are used as synonyms.
• Although manageable to very simple treatment, cholera has caused
seven pandemics,
• However, in the developed world, due to nearly universal advanced
water treatment and sanitation practices, cholera is no longer a major
health threat.
• The last major outbreak of cholera in the United States occurred in
1910–1911

8. • Agent
• Vibrios bacteria are a group of comma shaped Gram negative,
• Most enterobacteria (including vibrios) have two common antigens
their fl agella (H antigen).
• a phospholipid-protein-polysaccharide complex which forms the
endotoxin (O antigen).
Cases
• Most infections in cholera are mild or asymptomatic, and often get
missed.
• Incubation period
• Few hours ↔ 5 days

9. Enteric fever
• Typhoid fever, also known as enteric fever, or commonly just typhoid is an illness
caused by the bacterium Salmonella enterica serovar Typhi.
• Typhoid fever is characterized by a sustained fever as high as 40°C (104°F),
profuse sweating, gastroenteritis, and non-bloody diarrhea.
Agent
• Salmonella typhi, Salmonella para typhi (A,B);
• the bacilli survive in polluted water and soil;
• they are readily destroyed by heating at 60°C for 15 minutes, or by
pasteurization.
• Host
• 1. Age—Most cases occur during adolescence (5–19 years) due their food habits.
• People over 60 have greater chance to become carriers.

10. • Peak of cases occur during monsoon (July-September); unhygienic
milk, and contamination of water
• Incubation period 10–14 days.
• Diagnostics
• Blood culture
• Widal test
This is a serological test to detect H and O antibody developed in
patients of S. typhi and S. paratyphi infection
• Breaking the chain
• Water sanitation, cover food and water from flies, use of sanitary
latrines.

11. Acute bacterial gastroenteritis
• Food poisoning is an acute gastroenteritis caused by many bacteria/
toxins/ chemicals (fertilizers/ pesticides, Hg)/ vegetable or animal
poisons in contaminated food or drink.
• Agent
• Staphylococcus aureus (enterotoxin), Bacillus cereus (spores),
Salmonellae (typhimurium, choleraesuis), Clostridium botulinum (
botulinum toxin).
• Host
• Everyone is susceptible. People attending a mass feast falling ill are
prime suspects.
• Environment
• Breakage of hygiene in processing/cooking of food is the root of food
poisoning.

12. Poliomyelitis
• Persistent pockets of polio transmission in northern India, northern Nigeria
and the border between Afghanistan and Pakistan are the current focus of
the polio eradication initiative.
• As long as a single child remains infected, children in all countries are at
risk of contracting polio. Between 2003 and 2005, 25 previously polio-free
countries were reinfected due to imports of the virus.
• Agent
• Poliovirus Types I, II, III;
• Poliovirus Type III is the now the prevalent cause of paralytic poliomyelitis.
• The last case of Type II poliomyelitis occurred in India in 1999, and it is on
its way to be the first to be eradicated among the three.
• Type I polio still occurs but with decreasing frequency.

13. Host
• Under five children, especially those between 6 m – 3 y.
• In immune individuals, IgA antibodies against poliovirus are present in
the tonsils and gastrointestinal tract and are able to block virus
replication;
• IgG and IgM antibodies against PV can prevent the spread of the virus
to motor neurons of the central nervous system.
• Pregnancy seems to be a risk factor.

14. • Incubation period = 7–14 days.
• Non specific respiratory (fever, sore throat) and gastrointestinal (nausea,
vomiting, abdominal pain) symptoms.
• Acute flaccid paralysis (AFP) = sudden onset weakness and floppiness in,
1. Any part of the body of a child < 15 years
2. A person of any age in whom poliomyelitis is suspected Include all
cases with
1. Current flaccid paralysis (occurring within 5 weeks)
2. Past flaccid paralysis

15. • Prevention
• Personal hygiene, water sanitation, proper excreta disposal, good housing,
Vaccination
• Treatment. Paralytic polio has no treatment.
• Control
• Controlling the reservoir
• Isolate cases of poliomyelitis and dispose their excreta safely.
• Water sanitation, safe excreta disposal.
• Protecting the host

16. • Protecting the host
• Inactivated polio vaccine (IPV)
• The first inactivated virus vaccine was developed in 1952 by Jonas Salk, and
announced to the world on April 12, 1955.
• Oral poliomyelitis vaccine
• The OPV was introduced by Albert Sabin in 1957, produced by the repeated
passage of the virus through nonhuman cells at sub physiological
temperatures.
• It is a trivalent vaccine, i.e. bears all three types of virus grown in primary
monkey kidney/human diploid cells.
• Dosage. 2 drops oral at birth, 6, 10, 14 weeks. It is important to be completed
within 6 months. A booster may be given between 16–24 months.
• Method. Tilt the head of the child, open its mouth by pinching the cheeks and
drop the vaccine directly into tongue.

17. Hepatitis A
Agent
• Enterovirus or HAV, family Picornaviridae. It survives almost 10 weeks in water, and
resistant to heat, acid and usual levels of chlorination.
• NaOCl has been recommended as a disinfectant for fomites of hepatitis A patients.
Host
• Children have mostly mild or subclinical infections, but adults show severe disease.
Immunity may be natural or vaccine induced, both long lasting (due to persistent
IgG antibody).
Environment
• Poor water sanitation, overcrowding helps the spread of this feco-oral infection.
Mode
• Feco-oral (through food, fingers or water) parenteral (rare),
• Incubation period = 15–45 days depending on infective dose. Nonspecific symptoms
like malaise, vomiting, anorexia are much common than jaundice.

18. • Confirmation of hepatitis A
• Acute onset fever and jaundice (fever preceding jaundice), malaise, anorexia,
hepatomegaly, SGPT > 8 times of normal and serum bilirubin > 2 mg%. Serology
gives more important evidence.
• Lab
• 1. LFT to show bilirubin > 2 mg % and rise of SGPT
• 2. Demonstration of HAV particles or antigen in feces
• 3. Serology.
• Protecting the host
• AntiHAV immunoglobulin is given to
1. Travelers to endemic area
2. Close personal contacts of cases in households, day care centers,
epidemics
3. To control outbreaks in institutes
• A killed vaccine has been devised to be given IM twice at 6–18 months interval, in
children more than 1 year of age