Introduction to Microbiology and Common Microorganisms
By Arvind Sharma, B.Pharm, M.Pharm, Assistant Professor, MUIT
Introduction to Microbiology and Common Microorganisms
1.1 What is Microbiology?
Microbiology is the branch of science that studies microscopic living organisms (microorganisms) — those too small to be seen with the naked eye.
Think of it as 'the study of the tiny world that affects our health every day.'
Simple Definition: Micro = small | Bio = life | Logy = study → Study of small life forms
1.2 Types of Microorganisms
MNEMONIC: "BPFVAP"
- B – Bacteria (e.g., TB, cholera, typhoid)
- P – Protozoa (e.g., malaria, amoeba)
- F – Fungi (e.g., ringworm, candida)
- V – Viruses (e.g., COVID-19, HIV, measles)
- A – Algae (mostly harmless, rarely cause disease)
- P – Parasites/Helminths (e.g., roundworm, tapeworm)
| Microorganism | Cell Type | Example | Disease Caused |
|---|---|---|---|
| Bacteria | Prokaryote | Mycobacterium tuberculosis | Tuberculosis (TB) |
| Virus | Non-cellular (acellular) | SARS-CoV-2 | COVID-19 |
| Fungi | Eukaryote | Candida albicans | Oral thrush |
| Protozoa | Eukaryote | Plasmodium falciparum | Malaria |
| Helminths | Eukaryote (multicellular) | Ascaris lumbricoides | Ascariasis (worm) |
1.3 Beneficial vs Harmful Microorganisms
Not all microorganisms are harmful! Many are essential for life.
- Beneficial: Lactobacillus (in yogurt/gut), Nitrogen-fixing bacteria (soil), Yeast (bread/beer)
- Harmful (Pathogens): Cause infections, diseases, and epidemics
Pharmacist Connection: Pharmacists must understand microorganisms to counsel on antibiotics, vaccines, hygiene, and infection prevention.
1.4 Bacterial Structure (Easy Overview)
- Cell wall – gives shape and is the target of antibiotics like Penicillin
- Cell membrane – controls what enters/exits the cell
- DNA – genetic material (no nucleus in bacteria)
- Flagella – helps bacteria move
- Pili – helps bacteria attach to surfaces (important in infection)
MNEMONIC: "CWMDP = Can We Make Delicious Pastry?"
C – Cell wall
W – Wall membrane
M – Material (DNA)
D – Displace by Flagella (movement)
P – Pili (attachment)
1.5 Virus Structure (Key Points)
- Viruses are NOT cells — they are simpler than bacteria
- They have: Genetic material (DNA or RNA) + Protein coat (Capsid)
- Some have an outer lipid envelope (e.g., HIV, Influenza, COVID-19)
- Viruses can only reproduce INSIDE a host cell
Why important?: Soap destroys lipid envelopes of viruses like COVID-19. That's the science behind handwashing!
1.6 Normal Flora of Human Body
Our body has millions of bacteria that live on us normally and protect us — called Normal Flora.
- Skin: Staphylococcus epidermidis
- Gut: E. coli, Lactobacillus
- Mouth: Streptococcus viridans
Tip: When antibiotics kill normal flora, harmful organisms like Candida can overgrow — causing 'superinfection.'
Epidemiology: Introduction and Key Terms
2.1 What is Epidemiology?
Epidemiology is the study of how diseases spread in populations — who gets them, when, where, and why — so we can prevent and control them.
Simple analogy: If a disease is a fire, epidemiology is the investigation that finds the source, tracks where it spread, and puts it out.
2.2 Key Epidemiological Terms (Must Know!)
These terms are very important for exams and clinical understanding:
| Term | Simple Definition | Example |
|---|---|---|
| Epidemic | Sudden increase of a disease in a specific area/population beyond normal expected levels | COVID-19 in Wuhan city (2019) |
| Pandemic | Epidemic that spreads worldwide across countries and continents | COVID-19 (declared pandemic March 2020) |
| Endemic | Disease that is constantly present at a normal/expected level in a specific area | Malaria in parts of Africa, India |
| Outbreak | Sudden occurrence of a disease in a specific small community/area (smaller than epidemic) | Food poisoning at a school canteen |
| Quarantine | Restricting movement of people EXPOSED to a disease (but not yet sick) | Keeping COVID contacts at home for 14 days |
| Isolation | Separating people who ARE ALREADY SICK from others | COVID-positive patient in hospital room |
| Incubation Period | Time between exposure to pathogen and appearance of first symptoms | COVID-19: 2–14 days |
| Contact Tracing | Finding people who came in contact with an infected person to monitor/test them | Tracing COVID close contacts |
| Morbidity | The rate of people who become ILL due to a disease in a population | Morbidity rate of dengue in Kerala 2023 |
| Mortality | The rate of DEATHS caused by a disease in a population | COVID-19 mortality rate: ~2% |
MNEMONIC: "EE POQi ICM = 'Every Epidemic Produces Questions: Isolation Controls More'"
E – Epidemic
E – Endemic
P – Pandemic
O – Outbreak
Q – Quarantine
i – Isolation
I – Incubation period
C – Contact tracing
M – Morbidity & Mortality
2.3 Applications of Epidemiology
- Identify causes (etiology) of disease outbreaks
- Measure the magnitude of disease in population
- Plan and evaluate health programs and interventions
- Identify risk factors for diseases
- Guide vaccination and preventive strategies
- Monitor disease trends and emerging infections
Pharmacist Role in Epidemiology: Pharmacists report adverse drug reactions, unusual prescription patterns, and support surveillance. They are frontline workers during outbreaks.
2.4 Mode of Transmission
How does disease spread from one person/source to another?
Direct Transmission
- Person to person contact (touching, kissing, sexual contact)
- Droplet spread (sneezing, coughing within 1 meter)
- Direct contact with soil (tetanus)
Indirect Transmission
- Vehicle-borne: contaminated food, water (cholera, typhoid)
- Vector-borne: through insects (mosquitoes – malaria, dengue)
- Air-borne: droplet nuclei suspended in air (TB, COVID-19)
- Fomite-borne: contaminated objects like doorknobs, utensils
MNEMONIC: "DVAFo = 'Diseases Visit After Flying over'"
D – Direct contact
V – Vehicle-borne (food/water)
A – Airborne
F – Fomite-borne
o – (Vector-borne) Organism/insect
Communicable Diseases – Respiratory Infections
3.1 Introduction
Respiratory infections spread mainly through droplets (sneezing, coughing) or airborne particles. They are among the most common causes of illness worldwide.
Chickenpox (Varicella)
- Causative Agent: Varicella-Zoster Virus (VZV)
- Mode of Transmission: Droplet spread; direct contact with rash/blisters (highly contagious)
- Incubation Period: 14–21 days
- Clinical Features: Fever, then itchy blister-like rash (starts on chest/back, spreads to face and limbs). Crops of blisters at different stages.
- Prevention: Varicella vaccine (2 doses); avoid contact with infected persons; keep child home until all blisters have crusted
Pharmacist Role: Counsel parents to vaccinate children; advise calamine lotion for itching; warn not to use aspirin (risk of Reye's syndrome); educate on when to return to school
Measles (Rubeola)
- Causative Agent: Measles Virus (Paramyxovirus family)
- Mode of Transmission: Highly airborne — can linger in air for 2 hours after infected person leaves room
- Incubation Period: 10–14 days
- Clinical Features: 3 Cs: Cough, Coryza (runny nose), Conjunctivitis (red eyes). Then high fever and red rash spreading from face downward. Koplik spots (white spots inside mouth) — pathognomonic.
- Prevention: MMR vaccine at 9 months and 15 months (India schedule); vitamin A supplementation
Pharmacist Role: Counsel on MMR vaccination; explain Koplik spots for early identification; promote vitamin A for children in deficiency areas
MNEMONIC: "3 Cs of Measles = 'Can Cats Run?'"
C – Cough
C – Coryza (runny nose)
C – Conjunctivitis (red eyes)
Rubella (German Measles)
- Causative Agent: Rubella Virus (Togavirus family)
- Mode of Transmission: Droplet spread; direct contact
- Incubation Period: 14–21 days
- Clinical Features: Mild fever, swollen lymph nodes (especially behind ears), pink-red rash starting on face. VERY DANGEROUS in pregnancy — causes Congenital Rubella Syndrome (CRS): deafness, blindness, heart defects in baby.
- Prevention: MMR vaccine; women should be vaccinated before pregnancy
🔑 Pharmacist Role: Critical: Educate pregnant women and women of childbearing age to get vaccinated BEFORE pregnancy. Counsel that vaccination is safe pre-pregnancy but NOT during pregnancy.
Mumps
- Causative Agent: Mumps Virus (Paramyxovirus)
- Mode of Transmission: Droplet spread; direct contact
- Incubation Period: 16–18 days
- Clinical Features: Fever, headache, then painful swelling of parotid (salivary) glands — 'chipmunk cheeks.' Can cause orchitis (testicular swelling) in males — may lead to infertility.
- Prevention: MMR vaccine
Pharmacist Role: Advise MMR vaccination; counsel parents that orchitis (in adolescent males) is a complication that needs immediate medical attention
Influenza (Flu)
- Causative Agent: Influenza Virus (Types A, B, C) — Type A most severe
- Mode of Transmission: Droplet spread; airborne; contaminated surfaces
- Incubation Period: 1–4 days
- Clinical Features: Sudden onset: high fever, severe body aches, headache, dry cough, sore throat. Different from common cold — much more sudden and severe.
- Prevention: Annual flu vaccine (virus mutates yearly); hand hygiene; masks; avoid crowded places during flu season
Pharmacist Role: Promote annual flu vaccination (especially elderly, pregnant women, healthcare workers); dispense antiviral oseltamivir (Tamiflu) within 48 hours of symptoms; educate on flu vs cold differences
Special Influenza Variants
| Disease | Pathogen | Key Feature | Pharmacist Tip |
|---|---|---|---|
| Avian Flu (H5N1) | Influenza A H5N1 | Spread from birds to humans. High mortality (~60%). No easy human-to-human spread. | Advise avoiding contact with sick birds; report unusual deaths in poultry |
| Swine Flu (H1N1) | Influenza A H1N1 | 2009 pandemic. Spread human-to-human. Pregnant women at high risk. | Oseltamivir is drug of choice; vaccinate high-risk groups |
| SARS | SARS-CoV-1 (Coronavirus) | 2002–2003 outbreak. Severe pneumonia; 10% mortality. Spread by droplets. | Advise isolation; no specific antiviral; supportive care |
| MERS | MERS-CoV (Coronavirus) | Middle East Respiratory Syndrome. Spread from camels to humans. ~35% mortality. | Advise against contact with camels in affected areas |
| COVID-19 | SARS-CoV-2 | 2020 pandemic. Droplet + airborne spread. Variants (Delta, Omicron). Range from asymptomatic to death. | Vaccination (primary + booster); masks; handwashing; dispense antivirals per guidelines |
Diphtheria
- Causative Agent: Corynebacterium diphtheriae (bacterium)
- Mode of Transmission: Droplet spread; direct contact with discharge
- Incubation Period: 2–5 days
- Clinical Features: Sore throat, fever, and formation of a GREY PSEUDOMEMBRANE on the tonsils/throat that can block airway (life-threatening). Also produces toxin affecting heart and nerves.
- Prevention: DPT vaccine (Diphtheria, Pertussis, Tetanus); treatment with antitoxin + antibiotics (penicillin/erythromycin)
Pharmacist Role: Emphasize DPT vaccination in children; recognize pseudomembrane as emergency; counsel complete antibiotic course
Whooping Cough (Pertussis)
- Causative Agent: Bordetella pertussis (bacterium)
- Mode of Transmission: Highly contagious via droplets
- Incubation Period: 6–21 days
- Clinical Features: Three stages: (1) Catarrhal: runny nose, mild cough (2) Paroxysmal: severe coughing fits ending with a 'whoop' sound + vomiting (3) Convalescent: gradual recovery. Dangerous in infants — can be fatal.
- Prevention: DPT vaccine; antibiotics (azithromycin) early in disease; Tdap booster for adults
Pharmacist Role: Counsel parents on DPT schedule; advise that cough can last weeks; warn about risk to unvaccinated infants from infected adults
MNEMONIC: "3 Stages of Pertussis = 'Can People Cough?'"
C – Catarrhal stage (runny nose, mild cough)
P – Paroxysmal stage (severe whoop cough)
C – Convalescent stage (recovery)
Meningococcal Meningitis
- Causative Agent: Neisseria meningitidis (bacterium)
- Mode of Transmission: Droplet spread; close contact (overcrowded settings like hostels, military barracks)
- Incubation Period: 2–10 days
- Clinical Features: Sudden severe headache, high fever, stiff neck, sensitivity to light (photophobia), vomiting. Petechial rash (non-blanching red/purple spots) — medical emergency. Can cause death within 24 hours.
- Prevention: Meningococcal vaccine; chemoprophylaxis with rifampicin for close contacts
Pharmacist Role: Advise vaccination for high-risk groups (students, pilgrims to Mecca); recognize the non-blanching rash as emergency; provide rifampicin prophylaxis to contacts per prescription
Tuberculosis (TB)
- Causative Agent: Mycobacterium tuberculosis (bacterium)
- Mode of Transmission: Airborne — droplet nuclei that can stay suspended for hours
- Incubation Period: 2–12 weeks (for primary infection; reactivation can occur years later)
- Clinical Features: Persistent cough (>2 weeks), blood-tinged sputum (hemoptysis), weight loss, night sweats, low-grade fever, fatigue. Mainly lungs (pulmonary TB) but can affect any organ.
- Prevention: BCG vaccine at birth; DOTS (Directly Observed Treatment Short-course) — RNTCP/PMTB in India; complete 6-month regimen: HRZE (Isoniazid, Rifampicin, Pyrazinamide, Ethambutol)
Pharmacist Role: CRITICAL ROLE: Counsel on DOTS compliance; check drug interactions (rifampicin induces liver enzymes); advise on alcohol avoidance; monitor for side effects (isoniazid → peripheral neuropathy; give pyridoxine B6); report TB to health authorities (notifiable disease)
MNEMONIC: "TB Treatment Drugs = 'Her Recipe Produces Energy'"
H – Isoniazid (H)
R – Rifampicin (R)
P – Pyrazinamide (Z — but P for Pyrazinamide)
E – Ethambutol (E)
Ebola
- Causative Agent: Ebola Virus (Filovirus family) — multiple species
- Mode of Transmission: Direct contact with blood, secretions, organs, or bodily fluids of infected person or dead bodies. NOT airborne.
- Incubation Period: 2–21 days
- Clinical Features: Sudden fever, fatigue, muscle pain, headache → vomiting, diarrhea, rash → in severe cases: hemorrhage (bleeding from eyes, ears, mouth) — Ebola Hemorrhagic Fever. Very high mortality (25–90%).
- Prevention: No approved vaccine widely available (experimental vaccines exist); strict isolation; full PPE for healthcare workers; safe burial practices
Pharmacist Role: Educate public to avoid contact with dead bodies; promote reporting; explain use of PPE; counsel travelers to affected areas (West/Central Africa)
Communicable Diseases – Intestinal Infections
4.1 Introduction
Intestinal infections mainly spread through the FECO-ORAL route — contaminated food and water. Good sanitation and hygiene are the key to prevention.
MNEMONIC: "4 Fs of Feco-Oral Route = 'Flies Feed Filth Fast'"
F – Flies (vectors carrying pathogens from feces to food)
F – Food (contaminated food)
F – Fluid/Water (contaminated water)
F – Fingers (unwashed hands)
Poliomyelitis (Polio)
- Causative Agent: Poliovirus (Enterovirus — 3 types: 1, 2, 3)
- Mode of Transmission: Feco-oral route mainly; also droplet spread
- Incubation Period: 3–35 days
- Clinical Features: Most infections (>95%) are asymptomatic. Some: fever, headache, nausea. Paralytic polio: flaccid (floppy) paralysis — asymmetric, mainly legs. Can cause permanent disability or death (if respiratory muscles affected).
- Prevention: OPV (Oral Polio Vaccine — Sabin) given at birth, 6, 10, 14 weeks + IPV; India declared polio-free in 2014
Pharmacist Role: Promote Pulse Polio immunization; explain difference between OPV and IPV; counsel parents of children with sudden limb weakness to seek immediate care
Viral Hepatitis
- Causative Agent: Hepatitis Viruses (A, B, C, D, E)
- Mode of Transmission: Hep A & E: Feco-oral (contaminated food/water) | Hep B, C, D: Blood, sexual contact, mother to child
- Incubation Period: Varies: Hep A: 15–50 days; Hep B: 45–180 days
- Clinical Features: Jaundice (yellow eyes/skin), dark urine, pale stools, fatigue, nausea, abdominal pain. Hep B & C can become chronic → liver cirrhosis → liver cancer.
- Prevention: Hep A: Hepatitis A vaccine, safe water, hygiene | Hep B: HBV vaccine (at birth + 3 doses); avoid sharing needles; safe sex
Pharmacist Role: Dispense antivirals (tenofovir, entecavir for Hep B; sofosbuvir for Hep C); counsel on alcohol avoidance; explain jaundice vs normal tiredness; promote vaccination; check drug interactions in cirrhosis patients
| Type | Spread | Acute/Chronic | Vaccine |
|---|---|---|---|
| Hep A | Feco-oral | Acute only | Yes |
| Hep B | Blood/sexual/vertical | Can be chronic | Yes (3 doses) |
| Hep C | Blood mainly | Often chronic | No |
| Hep D | Blood (only with Hep B) | Chronic | Hep B vaccine prevents it |
| Hep E | Feco-oral (especially water) | Acute (severe in pregnancy) | Available (some countries) |
Cholera
- Causative Agent: Vibrio cholerae (bacterium) — produces cholera toxin
- Mode of Transmission: Contaminated water and food (feco-oral); no direct person-to-person
- Incubation Period: Few hours to 5 days
- Clinical Features: 'Rice-water stools' — profuse, watery diarrhea without pain. Rapid dehydration → can cause death within hours if untreated. Vomiting. No fever initially.
- Prevention: Safe water (boiling/chlorination); ORS (Oral Rehydration Solution); oral cholera vaccine; proper sewage disposal
Pharmacist Role: MOST IMPORTANT: Prepare and dispense ORS; educate on correct ORS preparation (1 liter water + WHO ORS packet); promote clean water; report to health authorities (notifiable disease)
Typhoid Fever
- Causative Agent: Salmonella typhi (bacterium)
- Mode of Transmission: Feco-oral — contaminated food and water; carriers are important source
- Incubation Period: 7–21 days
- Clinical Features: Step-ladder pattern of fever (increases each day), headache, coated tongue, rose spots on abdomen, bradycardia (slow heart rate relative to fever), constipation early → diarrhea later. Complications: intestinal perforation, hemorrhage.
- Prevention: Typhoid vaccine (Vi-CPS or Ty21a); safe water; food hygiene; identify and treat carriers
Pharmacist Role: Counsel on typhoid vaccine; dispense antibiotics (ciprofloxacin, azithromycin, ceftriaxone); warn about drug resistance patterns; educate on safe food and water practices
Amebiasis
- Causative Agent: Entamoeba histolytica (protozoan)
- Mode of Transmission: Feco-oral — contaminated food/water/hands
- Incubation Period: 2–4 weeks
- Clinical Features: Amebic dysentery: frequent loose stools with mucus and blood, abdominal cramps. Can spread to liver → Amebic Liver Abscess (right upper abdomen pain, fever).
- Prevention: Safe water and food; hand hygiene; identify and treat cyst passers (carriers)
Pharmacist Role: Dispense metronidazole (luminal + tissue amoeba); counsel to complete course; educate on hygiene; distinguish amebic vs bacillary dysentery
Acute Diarrheal Diseases
- Causative Agent: Multiple: Rotavirus, E. coli, Shigella, Salmonella, Campylobacter, etc.
- Mode of Transmission: Feco-oral — contaminated food, water, unwashed hands
- Incubation Period: Hours to days
- Clinical Features: Frequent loose watery stools, vomiting, fever (sometimes), abdominal cramps. Dehydration is the main danger — especially in children under 5.
- Prevention: ORS; Rotavirus vaccine; breastfeeding; zinc supplementation in children; safe water and hygiene
Pharmacist Role: Prepare and counsel on ORS; zinc dispensing; explain danger signs (sunken eyes, dry mouth, no urine for 8 hours → hospital); advise against unnecessary antibiotics for viral diarrhea
Worm Infestations (Helminthiasis)
- Causative Agent: Various: Roundworm (Ascaris), Tapeworm (Taenia), Pinworm (Enterobius), Hookworm (Ancylostoma)
- Mode of Transmission: Ingestion of worm eggs in contaminated food/water/soil; hookworm via skin penetration
- Incubation Period: Varies by worm type
- Clinical Features: Abdominal pain, nausea, nutritional deficiency (especially iron-deficiency anemia from hookworm), weight loss, rectal itching (pinworm). Children most affected.
- Prevention: Deworming programs (albendazole/mebendazole every 6 months for school children); proper sanitation; washing hands; wearing shoes
Pharmacist Role: Dispense albendazole 400mg (single dose) or mebendazole; counsel on national deworming day (India — February and August); educate on shoe-wearing to prevent hookworm
Food Poisoning
- Causative Agent: Bacterial toxins: Staphylococcus aureus, Clostridium botulinum, Bacillus cereus, Salmonella
- Mode of Transmission: Ingestion of contaminated food (improperly stored, cooked, or handled)
- Incubation Period: 30 minutes to 6 hours (S. aureus toxin); 12–72 hours (Salmonella)
- Clinical Features: Sudden onset of nausea, vomiting, diarrhea, abdominal cramps. Fever may be present. Usually self-limiting in 24–48 hours. Botulism — very serious: paralysis.
- Prevention: Proper food storage (refrigeration at <5°C), cooking temperatures (>70°C), personal hygiene in food handlers; avoid raw/undercooked foods
Pharmacist Role: Counsel on ORS and hydration; educate on safe food handling; report outbreaks; advise on danger signs requiring hospitalization
Communicable Diseases – Arthropod-Borne Infections
5.1 Introduction
Arthropod-borne infections (also called vector-borne diseases) are spread through the bites of insects like mosquitoes, flies, and ticks.
Key Vector: MOSQUITO is the most important vector — responsible for malaria, dengue, filariasis, and chikungunya.
MNEMONIC: "'MDFC' = 'Mosquitoes Destroy Four Cities'"
M – Malaria (Anopheles mosquito)
D – Dengue (Aedes aegypti mosquito)
F – Filariasis (Culex mosquito)
C – Chikungunya (Aedes mosquito)
Dengue Fever
- Causative Agent: Dengue Virus (Flavivirus — 4 serotypes: DENV 1,2,3,4)
- Mode of Transmission: Aedes aegypti mosquito bite (bites during daytime — dawn and dusk)
- Incubation Period: 4–10 days
- Clinical Features: High fever, severe headache, pain behind eyes, severe joint and muscle pain ('breakbone fever'), skin rash. Severe form: Dengue Hemorrhagic Fever (DHF) → platelet drop, bleeding, shock → fatal.
- Prevention: No approved vaccine widely available; vector control: eliminating stagnant water (coolers, tires, flower pots); repellents; full-sleeved clothing
Pharmacist Role: Monitor platelet count; advise PARACETAMOL only (NEVER ASPIRIN or IBUPROFEN — worsen bleeding); educate on warning signs (bleeding from gums, persistent vomiting, abdominal pain → emergency); promote dengue awareness campaigns
Malaria
- Causative Agent: Plasmodium species: P. falciparum (most dangerous), P. vivax, P. malariae, P. ovale
- Mode of Transmission: Female Anopheles mosquito bite (bites at night)
- Incubation Period: 7–30 days
- Clinical Features: Classic malaria triad: Fever (spiking, cyclical) + Chills + Sweating. Headache, body ache, anemia. P. falciparum: cerebral malaria, black-water fever — can be fatal within hours.
- Prevention: Insecticide-treated bed nets (ITNs); indoor residual spraying (IRS); anti-malarial drugs (prophylaxis for travelers); larval control; no vaccine widely deployed in India yet
Pharmacist Role: Dispense anti-malarials (chloroquine for P. vivax; artemisinin-based combination therapy — ACT for P. falciparum); counsel on complete course; educate on bed net use; check G6PD status before primaquine
MNEMONIC: "Malaria Triad = 'Fear Cold Sweat'"
F – Fever (high spiking)
C – Chills (rigors)
S – Sweating (drenching sweat)
Filariasis (Lymphatic Filariasis)
- Causative Agent: Wuchereria bancrofti (nematode/roundworm) — transmitted by Culex mosquito
- Mode of Transmission: Culex mosquito bite (bites at night)
- Incubation Period: Months to years (long incubation)
- Clinical Features: Acute: fever, painful lymph nodes. Chronic: ELEPHANTIASIS — massive swelling of legs, genitals due to blocked lymph vessels. Also hydrocoele in males.
- Prevention: Mass Drug Administration (MDA) — India gives DEC + Albendazole annually; mosquito control; protective clothing
Pharmacist Role: Participate in MDA programs; counsel communities on mass drug administration; dispense DEC (Diethylcarbamazine); educate on limb care in elephantiasis patients
Chikungunya
- Causative Agent: Chikungunya Virus (Alphavirus — Togaviridae family)
- Mode of Transmission: Aedes aegypti and Aedes albopictus mosquito bite (bites during day)
- Incubation Period: 2–12 days
- Clinical Features: High fever, severe joint pain (polyarthralgia — can be debilitating for months), rash, headache, muscle pain. The word 'Chikungunya' means 'that which bends up' in Makonde language — due to stooped posture from joint pain.
- Prevention: No specific vaccine or antiviral; vector control (eliminate stagnant water); repellents; full clothing
Pharmacist Role: Advise paracetamol and NSAIDs for joint pain; counsel that joint pain may last months; educate on mosquito control; differentiate from dengue (joint pain more prominent in chikungunya)
Communicable Diseases – Surface Infections
6.1 Introduction
Surface infections affect the skin, eyes, and superficial tissues. They spread through direct contact, contaminated objects, or vectors.
Trachoma
- Causative Agent: Chlamydia trachomatis (bacterium — obligate intracellular)
- Mode of Transmission: Direct contact with eye discharge; flies that land on eyes; sharing towels/cloths
- Incubation Period: 5–12 days
- Clinical Features: Repeated eye infections → scarring of eyelids → trichiasis (eyelashes turn inward and scratch cornea) → corneal opacification → BLINDNESS. Trachoma is the leading infectious cause of preventable blindness worldwide.
- Prevention: SAFE strategy: Surgery (trichiasis), Antibiotics (azithromycin), Face washing, Environmental improvement (sanitation, water)
Pharmacist Role: Dispense azithromycin (single dose); promote face washing campaigns; educate communities on the SAFE strategy; identify trichiasis cases for surgical referral
MNEMONIC: "Trachoma Prevention = 'SAFE'"
S – Surgery (for trichiasis)
A – Antibiotics (azithromycin)
F – Face washing
E – Environmental improvement
Tetanus
- Causative Agent: Clostridium tetani (bacterium) — produces tetanospasmin toxin
- Mode of Transmission: NOT person-to-person. Spores enter body through wounds (puncture wounds, dirty wounds, post-delivery — neonatal tetanus from unclean cord cutting)
- Incubation Period: 3–21 days
- Clinical Features: Muscle stiffness and spasms: trismus (lockjaw — unable to open mouth), risus sardonicus (fixed grin), opisthotonus (arched back), spasm of respiratory muscles → asphyxia → death. Any external stimulus (noise, touch) triggers painful spasms.
- Prevention: TT (Tetanus Toxoid) vaccine: 5-dose schedule in childhood; Td booster every 10 years; TT for pregnant women (2 doses); proper wound care; tetanus immunoglobulin for unvaccinated wounded patients
Pharmacist Role: Counsel on wound care and TT vaccination; dispense/advise tetanus immunoglobulin for unvaccinated; educate mothers on clean delivery practices; promote Td boosters for adults
Leprosy (Hansen's Disease)
- Causative Agent: Mycobacterium leprae (bacterium — grows very slowly)
- Mode of Transmission: Prolonged close contact with untreated leprosy patient; droplet/nasal discharge; NOT very contagious
- Incubation Period: Very long: 2–12 years!
- Clinical Features: Affects skin and peripheral nerves: skin patches (hypopigmented or reddish — loss of sensation), nerve thickening, loss of sensation in hands/feet (leading to injuries without pain), muscle weakness, deformities (claw hand, foot drop, facial changes). NOT a disease of 'rotting flesh' — that is a myth!
- Prevention: MDT (Multi-Drug Therapy): Dapsone + Rifampicin + Clofazimine for 6–12 months; early detection; no isolation needed (MDT renders patient non-infectious quickly)
Pharmacist Role: Dispense MDT correctly; fight stigma — educate that leprosy is curable and patients on MDT are not contagious; promote self-care for anesthetic limbs; encourage early reporting
Leprosy Myth Buster: Leprosy is NOT highly contagious. You CANNOT get it from a brief handshake. India is leprosy-eliminated (prevalence <1/10,000), but cases still occur. Fight stigma!
STDs, HIV/AIDS
7.1 Sexually Transmitted Diseases (STDs) — Overview
Also called Sexually Transmitted Infections (STIs) or Venereal Diseases (VDs). They spread primarily through unprotected sexual contact, but also through blood and from mother to child.
| STD | Causative Agent | Key Features | Treatment |
|---|---|---|---|
| Gonorrhea | Neisseria gonorrhoeae (bacteria) | Burning urination, pus discharge. Can cause pelvic inflammatory disease (PID) in women, infertility | Ceftriaxone + Azithromycin |
| Syphilis | Treponema pallidum (bacteria) | Painless ulcer (chancre) → rash → latent → tertiary: heart/brain damage | Benzathine Penicillin G |
| Chlamydia | Chlamydia trachomatis (bacteria) | Often asymptomatic. Can cause infertility, ectopic pregnancy in women | Doxycycline or Azithromycin |
| Herpes | Herpes Simplex Virus 2 (HSV-2) | Painful genital blisters/sores; recurrent episodes; no cure but antivirals control symptoms | Acyclovir (suppressive therapy) |
| Genital Warts | Human Papillomavirus (HPV) | Cauliflower-like warts; some strains cause cervical cancer | HPV vaccine; cryotherapy |
7.2 HIV/AIDS
What is HIV?
HIV = Human Immunodeficiency Virus. It attacks CD4+ T cells (helper T cells) — the 'generals' of the immune system. Without these, the body cannot fight infections.
AIDS = Acquired Immunodeficiency Syndrome = the final stage of HIV infection, when CD4 count falls below 200 cells/μL and the body is vulnerable to opportunistic infections.
HIV vs AIDS: HIV is the virus. AIDS is the condition (syndrome) caused by advanced HIV infection. Not everyone with HIV has AIDS.
Modes of Transmission (HIV)
- Unprotected sexual contact (most common route globally)
- Sharing needles/syringes (IV drug users)
- Blood transfusion with infected blood
- Mother to child (MTCT): during pregnancy, childbirth, or breastfeeding
MNEMONIC: "HIV Transmission = 'Sex, Needles, Blood, Babies'"
S – Sexual contact (unprotected)
N – Needles (shared IV drug use)
B – Blood transfusion
B – Babies (mother-to-child transmission)
HIV Does NOT Spread Through
- Hugging, handshakes, sharing utensils
- Mosquito bites or other insects
- Swimming pools, toilets
- Air or casual contact
Fight Stigma: HIV cannot spread through normal daily contact. People living with HIV deserve respect and support.
Clinical Stages of HIV
| Stage | Description | CD4 Count |
|---|---|---|
| Stage 1 (Acute HIV) | Flu-like illness (fever, swollen glands, rash) 2–4 weeks after infection. Person is highly infectious. | >500 cells/μL |
| Stage 2 (Asymptomatic / Latent) | No symptoms. Can last years. Person still infectious. CD4 count slowly falling. | 200–500 cells/μL |
| Stage 3 (Symptomatic HIV) | Weight loss, chronic diarrhea, fever, oral thrush, herpes zoster (shingles) | 200–500 cells/μL |
| Stage 4 (AIDS) | Opportunistic infections: TB, PCP (pneumocystis pneumonia), CMV, Cryptococcal meningitis, Kaposi's sarcoma | <200 cells/μL |
HIV Diagnosis
- ELISA test (screening) — detects antibodies; takes 6–12 weeks after infection (window period)
- Western Blot (confirmatory)
- Rapid HIV tests — fingerprick, results in 20 minutes
- CD4 count and Viral Load — to monitor disease progression and treatment
HIV Treatment — Antiretroviral Therapy (ART)
ART does not cure HIV but suppresses the virus to undetectable levels — allowing a near-normal lifespan.
- ART = combination of 3 drugs from at least 2 drug classes (HAART — Highly Active ART)
- Common classes: NRTIs (Tenofovir, Lamivudine), NNRTIs (Efavirenz, Nevirapine), PIs, Integrase inhibitors
- First-line in India (NACO guidelines): Tenofovir + Lamivudine + Efavirenz (TLE)
- U=U: Undetectable = Untransmittable — if viral load is undetectable on ART, cannot sexually transmit HIV
Prevention of HIV
- ABC strategy: Abstinence, Be faithful, Condom use
- PrEP (Pre-Exposure Prophylaxis): Tenofovir-based daily pill for high-risk individuals
- PEP (Post-Exposure Prophylaxis): 28-day ART course within 72 hours after exposure
- PPTCT (Prevention of Parent-to-Child Transmission): ART for HIV+ pregnant women
- Safe blood supply: Screening of donated blood
- Harm reduction: Needle exchange programs for IV drug users
- Voluntary Counseling and Testing (VCT) at ICTC centers
Role of Pharmacist in HIV/AIDS
- Counsel on ART adherence (>95% adherence needed to prevent resistance)
- Check drug interactions (rifampicin for TB vs ART — important!)
- Dispense ART from ART centers; maintain confidentiality
- Educate on side effects (efavirenz: vivid dreams, dizziness; tenofovir: renal monitoring)
- Fight stigma and discrimination — counsel families and communities
- Refer for ICTC testing and VCT
- Counsel on PEP for needle-stick injuries in healthcare workers
NACO: India's National AIDS Control Organization (NACO) runs the ART program providing FREE ART to all HIV+ individuals through government ART centers. Pharmacists at these centers play a crucial dispensing and counseling role.
QUICK REVISION — Master Summary Table
All Diseases at a Glance
| Disease | Agent | Vector/Route | Vaccine | Key Drug/Treatment |
|---|---|---|---|---|
| Chickenpox | VZV (virus) | Droplet/contact | Yes (Varicella) | Acyclovir; calamine |
| Measles | Measles virus | Airborne | Yes (MMR) | Supportive + Vit A |
| Rubella | Rubella virus | Droplet | Yes (MMR) | Supportive |
| Mumps | Mumps virus | Droplet | Yes (MMR) | Supportive |
| Influenza | Influenza virus | Droplet/airborne | Yes (annual) | Oseltamivir |
| COVID-19 | SARS-CoV-2 | Droplet/airborne | Yes (multiple) | Per protocol |
| Diphtheria | C. diphtheriae | Droplet | Yes (DPT) | Antitoxin + Penicillin |
| Whooping cough | B. pertussis | Droplet | Yes (DPT) | Azithromycin |
| Meningitis | N. meningitidis | Droplet | Yes | Penicillin/Ceftriaxone |
| TB | M. tuberculosis | Airborne | BCG | HRZE (6 months) |
| Ebola | Ebola virus | Direct contact bodily fluids | Experimental | Supportive + isolation |
| Polio | Poliovirus | Feco-oral | OPV/IPV | Supportive (no cure) |
| Hepatitis A | HAV | Feco-oral | Yes | Supportive |
| Hepatitis B | HBV | Blood/sexual | Yes (3 doses) | Tenofovir/Entecavir |
| Hepatitis C | HCV | Blood | No | Sofosbuvir |
| Cholera | V. cholerae | Contaminated water | Yes (oral) | ORS + Doxycycline |
| Typhoid | S. typhi | Feco-oral | Yes | Ciprofloxacin/Azithromycin |
| Amebiasis | E. histolytica | Feco-oral | No | Metronidazole |
| Worm infestations | Various helminths | Feco-oral/skin | No | Albendazole |
| Dengue | Dengue virus | Aedes mosquito | Limited | Paracetamol ONLY |
| Malaria | Plasmodium spp. | Anopheles mosquito | No (in India) | ACT/Chloroquine |
| Filariasis | W. bancrofti | Culex mosquito | No | DEC + Albendazole |
| Chikungunya | CHIKV | Aedes mosquito | No | Paracetamol + NSAIDs |
| Trachoma | C. trachomatis | Flies/direct contact | No | Azithromycin |
| Tetanus | C. tetani | Wound (spores) | Yes (TT) | TIG + Penicillin + TT |
| Leprosy | M. leprae | Prolonged contact | No | MDT (Dapsone+Rifam+Clofa) |
| HIV/AIDS | HIV (retrovirus) | Sexual/blood/MTCT | No | ART (TLE regimen) |
| Syphilis | T. pallidum | Sexual/blood | No | Benzathine Penicillin G |
| Gonorrhea | N. gonorrhoeae | Sexual | No | Ceftriaxone |
Best of Luck for Your Exams!
Remember: A Pharmacist is a Public Health Educator. Your role goes beyond dispensing — you can save lives through counseling and community education.