Human infections with Social Stigma.... Plague, TB, Leprosy, etc discussed for NEET 2020

1. Diseases with Social stigma : Plague, MTB, Leprosy), , STDs esp Syphilis & HIV, COVID - 19
Epidemic diseases reportable to the WHO (Plague, cholera, yellow fever, Corona, Ebola).
Global Pandemiscs at Present : Corona, TB,
Pandemics of Past : Spanish flu (Corona) , SARS, Plague, Cholera
Large scale Endemic diseases in India : TB, Corona, Rota virus diarrhoea, Malaria, Ascariasis, Amoebiasis
Disease Plague / Black
Death
Tuberculosis / Phthisis /
Koch’s ds / Consumption
Leprosy / Hansen's
disease (HD)
Nature of
Disease
Epidemic , pandemic
, Zoonosis; higly fatal
disease
granulomatous disease (see below).
-affects the lungs, but sometimes
other parts
It is the second-most common cause of
death from infectious disease world wide
(after HIV/AIDS).
Very long-term andslowly
developinginfection ; but
crippling disease once
developed (peripheral
parts like ears, nose,
finger tips simply fall of
causing disfigurement of
face)
Causative
Organism
bacterium
Yersinia pestis.
Mycobacterium tuberculosis (MTB).
-aerobic, non-motile bacillus, Acid fast
bacillus with high lipid content
It divides extremely slow - every 16-20 hrs)
bacteria
Mycobacterium
leprae or
M. lepromatosis
Mode of
Transmission
Multiple vectors, esp
Oriental rat flea
(Xenopsylla cheopsis)
Man to Man -droplet,
coughing or sneezing
physical contact –
Contact with active pulmonary TB patients :
By cough, sneeze, spit, they expel infectious
aerosol
-MTB withstands many disinfectants and
survive in a dry state for weeks.
(Even 10 bacteria cause an infection)
spread between people.
cough or contact with
fluid from the nose of an
infected person
Contrary to popular
belief, it is not highly
contagious (only infects
close contacts)
Other host /
reservoir
rodents None . Human carriers are big reservoirs None
Epidemiology All continents except
Australia.
-It mainly infects the
fleas that infest rats
(the first victims).
-Few remote areas
today also
-One-third of the world's population
is infected with TB;
- 80% of population infected in developing
countries (5-10% in Developed countries)
-1.5 million deaths / yr.
( 95% in developing countries).
Very few active pockets
in the world (Leprosy
villages)
Pandemiology massive pandemics
in AD-541, 1347,
1894; Plague is
inactive from 1959
World is undergoing TB Pandemic, esp d/t
HIV/ AIDS
Not Applicable
Incubation
Period
Few Days Few weeks to years
-may remain inactive for life in people
with strong immunity
Slowest incubation period
- 5-20 yrs

2. Disease Plague / Black
Death
Tuberculosis / Phthisis /
Koch’s ds / Consumption
Leprosy / Hansen's
disease (HD)
Risk Factors
(who can get
disease)
People in ware
houses / in contact
with Rats / infected
patients (esp
pulmonary plague)
-Contacts of people with active TB :
- overcrowding and malnutrition, poverty.
-Smokers, alcoholics, HIV patients
-health-care providers
-Other Chronic lung disease
-diabetes mellitus, corticosteroid
Only Close contacts
(thro nasal discharge)
Carrier state No carrier state.
(Highly Symptomatic)
Latent tuberculosis
-90% infections are asymptomatic carriers
-Carriers / Latent TB patients do not spread
the disease (because they do not cough)
Very long: 5-20 ysr
Pathology
3 types
bubonic plague -
swollen inflamed
lymph node in armpit
or groin
septicemic plague –
spread in blood –
called Black Death -
most infectious is
pneumonic plague
Tuberculosis may infect any part of the
body, but most commonly occurs in the
lungs
(pulmonary tuberculosis).
Bacteria invade and replicate within
endosomes of alveolar macrophages. (dust
cells) ; then survive for ever due to thick,
waxy mycolic acid capsule of MTB
MTB can reproduce inside the macrophage
and will eventually it (when above risk
factors exist).
TB is a granulomatous disease (see below)
granulomas* of the
nerves, respiratory tract,
skin, and eyes
symptoms Symptoms only in Active TB (most common
is Pulmonary TB (only 10 % of patients)
Classic symptoms of active Pulmonary TB
-chronic cough with
-sputum with blood ,
fever (esp evening rise),
-night sweats, and weight loss, fatigue.
(consumption = weight loss).
Extrapulmonary TB
-occurs in few active cases,
-spreads via blood / lymph from lungs, esp
in immuno-suppressed persons & kids
(esp CNS, Meninges, Uterus, Intestine,
Bones)
Initially,no symptoms for
5 to 20 years
- - poorly pigmented,
numb skin patches
granulomas of the nerves
(Lepromata) respiratory
tract, skin, and eyes.
analgesia =inability to feel
pain,
loss of parts of
extremities
unnoticed wounds.
Prevention Control Rat
population and Large
scale sanitization of
godowns &
warehouses
-segregate and isolate active TB patients
- anti-TB drug regimens
(till active symptoms disappear).
-Avoid contact with Active TB Patients
(coughing)
-screening people who are at high risk
with Tuberculin / Mantoux skin tests
or interferon-gamma release assays
-Vaccines
Bacillus Calmette-Guérin (BCG)
Live Attenuated Vaccine given at Birth
curable with a treatment
known as multidrug
therapy

3. before leaving hospital.
Diagnosis Culture and
sensitivity of
organism from
patient
Diagnosis of Active tuberculosis
chest X-ray
-multiple sputum / pus cultures
Nucleic acid amplification tests (PCR)
Diagnosis of Latent tuberculosis
-Mantoux tuberculin skin test
acid-fast bacilli in a biopsy
of the skin or by detecting
the DNA by PCR
Treatment Antibiotics -combinations of several antibiotics
-Directly observed therapy, (DOT)
i.e., a primary health care provider watches
the person take their medications,
-multiple drug-resistant TB (MDR-TB) -
requires 4 different antibiotics
for 18 to 24 months
multidrug therapy.[3]
dapsone and rifampicin
Prognosis Bubonic plague -
50% die
Pulmonary /
Septicimic plague –
100% death rate
-if left untreated, kills atleast 50% of
infected patients (over few months / yrs).
(Progression from Dormant / Latent TB
infection to Active TB disease occurs when
the bacilli overcome the immune system
(immunosuppression, HIV., Steroid Rx or
superimposed on pnuempnia - Corona /
Measles / Influenza , etc
Granuloma
Macrophages,T lymphocytes, B lymphocytes, and fibroblasts aggregate to form granulomas, with lymphocytes
surrounding the infected macrophages.
When other macrophages attack the infected macrophage, they
fuse together to form a giant multinucleated cell in the alveolar lumen.
The granuloma prevents dissemination of the mycobacteria and provide a local environment for interaction of
cells of the immune system.
N.P. : Bacteria use the granulomas to avoid destruction by the host's immune system.
The WHO declared TB a "global health emergency" in 1993, & started Global Plan to Stop Tuberculosis
The World Health Organization, Bill and Melinda Gates Foundation, and US Govt