HIV/AIDS, TB, & MALARIA

HIV (Human Immunodeficiency Virus)

The retrovirus that targets and destroys CD4+ T-lymphocytes.

AIDS (Acquired Immunodeficiency Syndrome)

The late stage of HIV with CD4+ count below 200 cells/uL or specific opportunistic infections.

HIV Transmission Modes

Unprotected sexual contact, contaminated blood products/shared needles, and vertical transmission.

Factors Raising HIV Transmission

High viral load, co-existing STIs, needle sharing, and lack of access to testing/treatment.

HIV Mitigation: Health Education

Condom distribution and harm reduction programs.

U=U (Undetectable = Untransmittable)

ART suppressing viral load to undetectable levels prevents sexual transmission.

PrEP (Pre-Exposure Prophylaxis)

Daily prophylactic medication taken by high-risk individuals to prevent HIV infection.

PMTCT

Prevention of Mother-to-Child Transmission using ART during pregnancy and infant prophylaxis.

HIV Life Cycle: Binding & Fusion

Virus attaches to CD4 and co-receptors (CCR5/CXCR4) and fuses with host cell membrane.

HIV Life Cycle: Reverse Transcription

Viral reverse transcriptase converts viral RNA into single/double-stranded DNA.

HIV Life Cycle: Integration

Viral integrase enzyme inserts HIV DNA into host genomic DNA.

HIV Life Cycle: Replication & Assembly

Host machinery transcribes viral RNA and synthesizes viral polyproteins.

HIV Life Cycle: Budding & Maturation

New viral particles bud off; HIV protease cleaves polyproteins to form mature infectious virions.

Most Common Opportunistic Infection (Resource-Limited)

Tuberculosis (TB).

Social Determinants of HIV

Stigma, discrimination, lower socioeconomic status, lack of healthcare access, and gender inequalities.

Latent TB

M. tuberculosis contained by immune system; asymptomatic, non-contagious, with normal chest X-rays.

Active TB

Immune system fails to contain bacteria; individual is symptomatic, has abnormal tests, and is infectious.

TB/HIV Coinfection (Double Trouble)

HIV weakens cell-mediated immunity, accelerating latent to active TB progression, and vice versa.

Public Health Implications of TB

Requires massive investments, expanded DOTS, rapid diagnostics, and MDR-TB regimens.

Malaria Transmission

Vector-borne transmission via the bite of an infected female Anopheles mosquito.

Malaria Parasite and Vector

Parasite: Plasmodium species (most severe: P. falciparum); Vector: Female Anopheles mosquito.

Malaria Life Cycle: Sporozoite Stage

Mosquito injects sporozoites into host, infecting liver cells and maturing into schizonts releasing merozoites.

Malaria Life Cycle: Erythrocytic Stage

Merozoites infect red blood cells, replicating and bursting synchronously to cause fever spikes.

Malaria Life Cycle: Gametocyte Stage

Merozoites differentiate into gametocytes, ingested by a feeding mosquito to complete sexual reproduction.

Environmental Factors for Malaria Prevalence

Tropical/subtropical warm climates, high humidity, standing water, and lack of housing infrastructure.

Malaria Prevention: Agent Strategies

Antimalarial therapies and artemisinin-based combination therapies (ACTs).

Malaria Prevention: Vector Strategies

Insecticide-treated bed nets (ITNs), indoor residual spraying (IRS), and larval control.

Malaria Prevention: Host/Environment Strategies

Malaria vaccines (RTS,S/R21), clearing standing water, and personal protective gear.