MICROBIAL DISEASES

Tuberculosis

• TB is an airborne disease caused by the bacterium Mycobacterium tuberculosis (M. tuberculosis)

• Over 9 million new cases and 2 million deaths per year worldwide

• 1/3rd of the world’s population is infected with M. tuberculosis

Transmission of TB• TB is spread from person to person through the air. The dots in

the air represent droplet nuclei containing tubercle bacilli.

Causes• Mycobacterium tuberculosis

– Highly aerobic– Infects lungs– Divides every 15-20 hours – Unable to be digested by microphages– Very resistant to many disinfectants, acid, alkali, drying, etc.

• Contagious, spread through air by inhalation of airborne bacteria from infected

• Easier to contract with weak immune system

Symptoms

• Cough (with bloody sputum), loss of appetite, fever, loss of energy/weight, night sweats,

• Could spread to other parts of the body causing other symptoms

Diagnosed

• Skin test• Chest X-rays• Analysis of sputum

Treatment/Prevention

• Positive Skin Test, Negative X-Ray:– Antibiotic:• Isoniazid

• Positive Skin Test, Positive X-Ray:– Antibiotics• Isoniazid, Rifampin, Ethambutol, Pyrazinamide

• Prevention: BCG Vaccine

Before and After

Prevention• Tuberculosis prevention and control

efforts primarily rely on the vaccination of infants and the detection and appropriate treatment of active cases.

• The World Health Organization has achieved some success with improved treatment regimens, and a small decrease in case numbers

Vaccines• The only available vaccine as of 2015 is Bacillus

Calmette-Guérin (BCG).

• In children it decreases the risk of getting the infection by 20% and the risk of infection turning into disease by nearly 60%.

• It is the most widely used vaccine worldwide, with more than 90% of all children being vaccinated The immunity it induces decreases after about ten

Epidemiology• Tuberculosis is the second-most common cause of death from

infectious disease (after those due to HIV/AIDS)

• The total number of tuberculosis cases has been decreasing since 2005, while new cases have decreased since 2002.

• China has achieved particularly dramatic progress, with about an 80% reduction in its TB mortality rate between 1990 and 2010. The number of new cases has declined by 17% between 2004–2014.

• Tuberculosis is more common in developing countries; about 80% of the population in many Asian and African countries test positive in tuberculin tests

1. What is HIV?Human Immunodeficiency Virus

an RNA based virus that causes AIDS 1. Attacks the Immune System

2. Destroys the body’s defenses against diseases

3. Body becomes vulnerable to infections & cancers that don’t normally develop in healthy people

What does HIV look like?

HIV Capsule HIV

Structural Biology of HIV

• Diameter of 100-120 nm with a spherical morphology

• Cone-shaped core surrounded by lipid matrix containing key surface antigens and glycoproteins

• Viral core contains 2 copies of genomic RNA, reverse transcriptase, integrase and protease

1. T4 or CD4 Cell 2. Antibodies

2. Two Key Parts of the Immune System

HIV

Healthy T Cell & Infected T Cell

HIV Particles(yellow)

T4 cell are particularly important in the adaptive immune system. These cells help suppress or regulate immune responses

HIV Transmission

Requires:

1. Infected body fluid

AND

2. Entry into body

3. Infected body fluids

Four Fluids, if infected, can transmit HIV

a. Blood

b. Semen

c. Vaginal Secretions

d. Breast Milk

If these enter the body

4. Which Fluids are safe? Four Fluids that can’t transmit HIV

a. Spit/saliva

b. Pee/Urine

c. Sweat

d. Tears

5. HIV TransmissionThree Most frequent ways to get infected

1. Unprotected sexual intercourse

2. Injected Drug Use

3. From an infected mother to her infant.

Other, much more rare, ways to get infected

a. Blood Transfusions / Organ Transplant (1:600,000)

b. Health Care Setting

Diagnosis

• Diagnosis is done by testing a person’s blood for the presence of antibodies to HIV.

• Antibodies are generally not detectable until 3 to 6 months following infection.

• ELISA and Western Blots are generally used to test of HIV antibodies.

Polymerase Chain Reaction (PCR)

• Looks for HIV DNA in the WBCs of a person.• PCR amplifies tiny quantities of the HIV DNA present, each

cycle of PCR results in doubling of the DNA sequences present.

• The DNA is detected by using radioactive or biotinylated probes.

• Once DNA is amplified it is placed on nitrocellulose paper and allowed to react with a radiolabeled probe, a single stranded DNA fragment unique to HIV, which will hybridize with the patient’s HIV DNA if present.

• Radioactivity is determined.

MALARIA

Introduction• Malaria is probably one of the oldest diseases known to

mankind that has had profound impact on our history.

• It is a huge social, economical and health problem, particularly in the tropical countries.

• Malaria is a vector-borne infectious disease caused by single-celled protozoan parasites of the genus Plasmodium.

• Malaria is transmitted from person to person by the bite of female mosquitoes.

Female Anopheles Mosquitos transmit Malaria

What causes Malaria

• Malaria is caused by a parasite called Plasmodium, which is transmitted via the bites of infected mosquitoes. In the human body, the parasites multiply in the liver, and then infect red blood cells.

• Transmission of Malaria do not occur <160c and >330c

Malaria Kills more people than AIDS

• Malaria kills in one year what AIDS kills in 15 years. For every death due to HIV/AIDS there are about 50 deaths due to malaria. To add to the problem is the increasing drug resistance to the established drug.

Broad clinical manifestations of Malaria

• Fever • Sweating • Anemia • Splenomagaly (enlarged spleen) • Irratability • Coma, Retinal Hemorrages • Respiratory distress syndrome

Laboratory Diagnosis

• Laboratory diagnosis of malaria can be made through microscopic examination of thick and thin blood smears. Thick blood smears are more sensitive in detecting malaria parasites because the blood is more concentrated allowing for a greater volume of blood to be examined; however, thick smears are more difficult to read

Blood collected with sterile technique

Making of Thick smear

How a thick smear looks

Appearance of Thick and Thin Smears

Microscopy• Malaria parasites can be identified by

examining under the microscope a drop of the patient's blood, spread out as a "blood smear" on a microscope slide. Prior to examination, the specimen is stained (most often with the Giemsa stain) to give to the parasites a distinctive appearance. This technique remains the gold standard for laboratory confirmation of malaria

Microscopic demonstration still the Gold standard in Diagnosis

Blood smear stained with

Giemsa’s stain

Epidemiology• Malaria continues to be one of the most

important and devastating infectious diseases in developing areas of the world. Worldwide, over 40% of the population lives in areas where malaria transmission occurs (i.e., parts of Africa, Asia, the Middle East, Central and South America, Hispaniola, and Oceania)

Control of Malaria

• Elimination of Mosquito breeding places,• National improvements on health and

Hygiene.• Use of Mosquito nets, treated with Pyrithrin• Clothing with sleeves, and long trousers • Use of Mosquito repellents