SHIGELLA

Source: THEPRINT

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Context

• ICMR has partnered with an Indian vaccine manufacturer to co-develop and commercialize the vaccine.
• The vaccine candidate developed by ICMR's National Institute for Research in Bacterial Infections (NIRBI) has shown robust results in animal studies and is now progressing towards human trials.

Details

Background

• Shigella, a highly infectious bacterium causing shigellosis, remains a significant public health challenge globally, particularly in low and middle-income countries.
• Shigella causes severe diarrheal diseases, particularly in children under five years of age.
• Despite its significant impact, no approved vaccine currently exists.
• The development of a vaccine is complicated by Shigella's antigenic diversity, which includes multiple species, serotypes, and sub-serotypes.
• In 2019, ICMR licensed the technology for scaling up and commercializing its Shigella vaccine to MSD-Wellcome Trust Hilleman Laboratories.
• The deal fell through due to the COVID-19 pandemic and Hilleman Laboratories' relocation from India to Singapore.

Importance of the Vaccine

• Epidemiological Impact:
  • Shigella causes approximately 125 million diarrheal episodes and around 160,000 deaths annually, with a third of these deaths occurring in children under five.
  • In India, Shigella is endemic and has caused numerous outbreaks, highlighting the urgent need for an effective vaccine.
• Public Health Benefits:
  • A successful vaccine could significantly reduce morbidity and mortality associated with shigellosis.
  • It would provide targeted protection for high-risk groups, especially young children, and help interrupt transmission within communities.
• Economic and Healthcare Savings:
  • Investing in a Shigella vaccine could lead to long-term cost savings by reducing healthcare expenses related to treatment and preventing economic losses associated with illness.

Shigella

• Shigella is a genus of bacteria known to cause an infectious disease called shigellosis, which is characterized by diarrhea, fever, and stomach cramps.
• It primarily affects the intestines and is a significant public health concern worldwide.

Species

• Shigella dysenteriae
• Shigella flexneri
• Shigella boydii
• Shigella sonnei

Epidemiology

• Global Impact:Shigellosis is prevalent worldwide, with higher incidences in developing countries.
• Transmission:The primary mode of transmission is fecal-oral, often through contaminated food and water, and direct person-to-person contact.
• At-Risk Populations:Children under five, travelers to endemic regions, and individuals in institutional settings (like daycares and prisons) are particularly at risk.
• Invasion and Spread:Shigella invades the epithelial cells of the colon, causing cell death and inflammatory responses.
• Virulence Factors:Key virulence factors include Shiga toxin (produced by S. dysenteriae) and type III secretion systems that help the bacteria evade the host's immune response.

Symptoms

• Diarrhea (often bloody)
• Abdominal pain and cramps
• Fever
• Tenesmus (a feeling of incomplete defecation)
• Complications:Severe cases can lead to dehydration, hemolytic uremic syndrome (HUS), and reactive arthritis.

Indian Council of Medical Research

• The Indian Council of Medical Research (ICMR) is the apex body in India for the formulation, coordination, and promotion of biomedical research.
• It is one of the oldest and largest medical research bodies in the world, playing a pivotal role in the advancement of health research in India.

History and Evolution

• Establishment:ICMR was originally established in 1911 as the Indian Research Fund Association (IRFA) and was re-designated as ICMR in 1949.
• Initial Focus:The primary focus was on conducting research on communicable diseases prevalent in India.
• Expansion:Over the years, ICMR expanded its research scope to include non-communicable diseases, basic medical sciences, and advanced medical research.

Organizational Structure

• Governing Body:ICMR operates under the Department of Health Research, Ministry of Health and Family Welfare, Government of India.
• Headquarters:New Delhi.
• Key Leadership:
  • Director General: The current head of ICMR, responsible for overall administration and research direction.
  • Scientific Advisory Board: Comprises eminent scientists and experts who guide ICMR’s research agenda.
• Institutes and Centers:ICMR oversees a network of 27 national research institutes, each specializing in different health and medical research areas.

Mission and Objectives

• Mission:
  • To generate, manage, and disseminate knowledge through high-quality biomedical research.
  • To develop infrastructure and human resources for health research.
  • To translate research findings into health policy and practice.
• Objectives:
  • Conducting and supporting research in national health priorities.
  • Enhancing research capacity and infrastructure.
  • Promoting innovation and collaboration in health research.
  • Disseminating research findings to stakeholders and the public.

Key Programs and Initiatives

• National Tuberculosis Control Program (NTCP):Research and development to combat tuberculosis.
• National AIDS Control Program (NACP):Studies and interventions to control HIV/AIDS.
• Integrated Disease Surveillance Program (IDSP):Monitoring and surveillance of communicable diseases.
• Maternal and Child Health Programs:Research on maternal and child health to reduce mortality and morbidity.
• Non-Communicable Disease Control Programs:Initiatives targeting lifestyle diseases and promoting preventive health.

Summary of Unicellular organisms

Type	Classification	Characteristics	Examples	Habitats
Bacteria	Kingdom: Bacteria	Prokaryotic, no nucleus, single circular DNA, cell wall, diverse metabolic pathways	Escherichia coli, Streptococcus	Soil, water, human body, extreme environments
Archaea	Kingdom: Archaea	Prokaryotic, no nucleus, unique membrane lipids, extremophiles	Methanogens, Halophiles	Extreme environments (hot springs, salt lakes)
Protozoa	Kingdom: Protista	Eukaryotic, nucleus, heterotrophic, motile (cilia, flagella, pseudopodia)	Amoeba, Paramecium, Plasmodium	Freshwater, marine, soil, host organisms
Algae	Kingdom: Protista	Eukaryotic, nucleus, photosynthetic, diverse forms (unicellular to multicellular)	Chlamydomonas, Euglena, Chlorella	Freshwater, marine, moist environments
Fungi (Yeasts)	Kingdom: Fungi	Eukaryotic, nucleus, heterotrophic, cell wall made of chitin, reproduce by budding or fission	Saccharomyces cerevisiae, Candida	Soil, plant surfaces, human body
Cyanobacteria	Kingdom: Bacteria	Prokaryotic, photosynthetic, chlorophyll a, often form colonies, nitrogen fixation	Anabaena, Nostoc	Freshwater, marine, terrestrial environments
Diatoms	Kingdom: Protista	Eukaryotic, nucleus, photosynthetic, silica cell walls, diverse shapes and sizes	Navicula, Cyclotella	Freshwater, marine
Dinoflagellates	Kingdom: Protista	Eukaryotic, nucleus, photosynthetic or heterotrophic, two flagella, bioluminescent	Noctiluca, Ceratium	Marine, freshwater
Slime Molds	Kingdom: Protista	Eukaryotic, nucleus, amoeboid stage, spore-producing fruiting bodies	Physarum, Dictyostelium	Forests, decaying logs, soil
Radiolarians	Kingdom: Protista	Eukaryotic, nucleus, intricate silica skeletons, axopodia (stiff pseudopodia)	Acantharea, Polycystina	Marine
Foraminiferans	Kingdom: Protista	Eukaryotic, nucleus, calcium carbonate shells, reticulopodia (branching pseudopodia)	Globigerina, Elphidium	Marine, freshwater
Ciliates	Kingdom: Protista	Eukaryotic, nucleus, covered with cilia for movement and feeding, complex cells	Paramecium, Stentor	Freshwater, marine, soil

Sources:

THEPRINT

PRACTICE QUESTION Q: With reference to Shigella bacteria, consider the following statements: 1. Shigella is a genus of bacteria that causes dysentery in humans. 2.All species of Shigella are capable of producing Shiga toxin. 3.Shigella bacteria are motile and can move using flagella. Which of the statements given above is/are correct? (a) 1 and 2 only (b) 1 and 3 only (c) 2 and 3 only (d) 1 only Answer: (d)