Lesson 11: The Multisystem Viruses

Byadmin

August 25, 2022

Multisystem viruses are those that can affect multiple organ systems within a host, often leading to widespread (generalized infections) and severe disease. These viruses can cause systemic infections, and their symptoms may vary widely depending on the organs or tissues they affect.

A. Veterinary Multisystem Viruses

1. Canine Parvovirus

  • Family: Parvoviridae
  • Genus: Parvovirus
  • Host: Dogs (especially puppies)
  • Transmission: Fecal-oral route, contaminated environments, direct contact with infected dogs.
  • Pathogenesis: Attacks rapidly dividing cells in the gastrointestinal tract, bone marrow, and lymphoid tissues, leading to severe enteritis and immunosuppression.
  • Clinical Signs: Vomiting, diarrhea (often bloody), lethargy, fever, dehydration.
  • Prevention: Vaccination, hygiene, and sanitation in kennels and homes.

2. Feline Panleukopenia Virus

  • Family: Parvoviridae
  • Genus: Parvovirus
  • Host: Cats (especially kittens)
  • Transmission: Fecal-oral route, contaminated surfaces, direct contact.
  • Pathogenesis: Similar to canine parvovirus; it targets rapidly dividing cells in the intestine and bone marrow, leading to severe leukopenia and enteritis.
  • Clinical Signs: Vomiting, diarrhea, lethargy, fever, inappetence, and sudden death in young kittens.
  • Prevention: Vaccination and maintaining a clean environment.

3. Bovine Viral Diarrhea Virus (BVDV)

  • Family: Flaviviridae
  • Genus: Pestivirus
  • Host: Cattle
  • Transmission: Direct contact with infected animals, contaminated feed, and environmental sources.
  • Pathogenesis: Causes immunosuppression, reproductive issues, and gastrointestinal disease; persistent infections may occur in utero.
  • Clinical Signs: Diarrhea, respiratory disease, reproductive failures, and immunosuppression.
  • Prevention: Vaccination, biosecurity measures, and culling of persistently infected animals.

4. Porcine Reproductive and Respiratory Syndrome Virus (PRRSV)

  • Family: Arteriviridae
  • Genus: Arterivirus
  • Host: Pigs
  • Transmission: Aerosols, direct contact, contaminated equipment, and fomites.
  • Pathogenesis: Affects the immune system, leading to respiratory illness and reproductive failure.
  • Clinical Signs: Respiratory distress, reproductive issues (abortions, stillbirths), lethargy.
  • Prevention: Biosecurity, vaccination, and management practices.

Medical Multisystem Viruses

1. Human Immunodeficiency Virus (HIV)

  • Family: Retroviridae
  • Genus: Lentivirus
  • Host: Humans
  • Transmission: Blood, sexual contact, and from mother to child during childbirth or breastfeeding.
  • Pathogenesis: Attacks CD4+ T cells, leading to immunosuppression and increased susceptibility to opportunistic infections and cancers.
  • Clinical Signs: Acute retroviral syndrome (fever, fatigue, swollen lymph nodes), followed by asymptomatic stage, leading to AIDS if untreated.
  • Prevention: Safe sex practices, needle exchange programs, pre-exposure prophylaxis (PrEP), and antiretroviral therapy (ART).

2. Dengue Virus

  • Family: Flaviviridae
  • Genus: Flavivirus
  • Disease: Dengue Fever, Dengue Hemorrhagic Fever
  • Host: Humans (also affects primates)
  • Transmission: Aedes mosquitoes (Aedes aegypti, Aedes albopictus).
  • Pathogenesis: Viral replication in endothelial cells leads to increased vascular permeability, hemorrhagic fever, and shock.
    • Systems Affected:
      • Immune system: Can lead to immune-mediated damage.
      • Vascular system: Causes increased vascular permeability, which can lead to hemorrhage.
      • Liver: Hepatic injury.
      • CNS: Rare cases involve encephalitis or other CNS complications
  • Clinical Signs: High fever, severe headache, retro-orbital pain, myalgia, rash, and in severe cases, dengue hemorrhagic fever or shock syndrome.
  • Prevention: Mosquito control measures, vaccines (Dengvaxia, but only for those previously infected), and personal protective measures (repellents, clothing).

3. Ebola Virus

  • Family: Filoviridae
  • Genus: Ebolavirus
  • Host: Humans and primates (e.g., monkeys, gorillas)
  • Disease: Ebola Virus Disease (EVD)
  • Transmission: Direct contact with infected bodily fluids, contaminated surfaces, and handling infected animals.
  • Pathogenesis: Infects endothelial cells, immune cells, and hepatocytes, causing severe hemorrhagic fever and multi-organ failure.
  • Systems Affected:
    • Immune system: Suppresses immune response.
    • Liver: Leads to liver damage.
    • Gastrointestinal system: Causes vomiting, diarrhea, abdominal pain.
    • Vascular system: Damages blood vessels, causing hemorrhage.
    • Central Nervous System (CNS): In some cases, leads to neurological complications.
  • Clinical Signs: Fever, severe headache, muscle pain, weakness, diarrhea, vomiting, and hemorrhagic symptoms in severe cases.
  • Prevention: Vaccination (rVSV-ZEBOV), strict hygiene, safe burial practices, and avoiding contact with infected individuals.

4. Zika Virus

  • Family: Flaviviridae
  • Genus: Flavivirus
  • Host: Humans (and other primates)
  • Transmission: Aedes mosquitoes, sexual transmission, and maternal-fetal transmission.
  • Pathogenesis: Virus targets neural progenitor cells during pregnancy, potentially leading to congenital Zika syndrome.
  • Clinical Signs: Mild fever, rash, conjunctivitis, joint pain; severe cases can lead to microcephaly in newborns.
  • Prevention: Mosquito control, avoiding mosquito bites, and safe sexual practices.

5. Hantavirus

  • Family: Hantaviridae
  • Disease: Hantavirus Pulmonary Syndrome (HPS), Hemorrhagic Fever with Renal Syndrome (HFRS)
  • Transmission: Aerosolized particles from rodent urine, droppings, or saliva.
  • Systems Affected:
    • Respiratory system: Causes pulmonary edema.
    • Renal system: Leads to kidney failure (in HFRS).
    • Vascular system: Increased vascular permeability, hemorrhage.
  • Symptoms: Fever, muscle aches, shortness of breath, renal failure.

6. Cytomegalovirus (CMV)

  • Family: Herpesviridae
  • Disease: CMV infection, congenital CMV
  • Transmission: Body fluids (saliva, blood, urine), vertical transmission.
  • Systems Affected:
    • Immune system: Particularly dangerous for immunocompromised individuals.
    • Liver: Can cause hepatitis.
    • CNS: Encephalitis in immunocompromised patients.
    • Eyes: Retinitis, especially in AIDS patients.
  • Symptoms: Fever, fatigue, in severe cases retinitis, encephalitis, pneumonia, and organ failure.

7. Yellow Fever Virus

  • Family: Flaviviridae
  • Disease: Yellow Fever
  • Transmission: Aedes mosquitoes.
  • Systems Affected:
    • Liver: Hepatitis and jaundice.
    • Kidneys: Renal failure.
    • Heart: Myocarditis.
    • Gastrointestinal system: Hemorrhage.
  • Symptoms: Fever, jaundice, hemorrhage, multi-organ failure.

8. Herpes Simplex Virus (HSV)

  • Family: Herpesviridae
  • Disease: Herpes Simplex Infections
  • Transmission: Direct contact with infected secretions.
  • Systems Affected:
    • Skin and mucous membranes: Oral and genital lesions.
    • CNS: Can cause encephalitis.
    • Liver: In neonatal infections, can cause hepatitis.
    • Eye: Can cause keratitis and lead to blindness.
  • Symptoms: Painful lesions, fever, in severe cases encephalitis and hepatitis.

9. SARS-CoV-2 (COVID-19)

  • Family: Coronaviridae
  • Disease: Coronavirus Disease 2019 (COVID-19)
  • Transmission: Respiratory droplets, contact with contaminated surfaces.
  • Systems Affected:
    • Respiratory system: Pneumonia, Acute Respiratory Distress Syndrome (ARDS).
    • Cardiovascular system: Myocarditis, thromboembolic events.
    • Renal system: Acute kidney injury.
    • CNS: Stroke, encephalitis, anosmia, dysgeusia.
    • Gastrointestinal system: Diarrhea, vomiting, liver damage.
  • Symptoms: Fever, cough, shortness of breath, in severe cases multi-organ failure.
  1. Measles Virus
  • Family: Paramyxoviridae
  • Disease: Measles
  • Transmission: Respiratory droplets.
  • Systems Affected:
    • Respiratory system: Pneumonia.
    • CNS: Can cause encephalitis and subacute sclerosing panencephalitis (SSPE).
    • Immune system: Temporary suppression of the immune system, leading to increased susceptibility to secondary infections.

Symptoms: Fever, cough, rash, in severe cases encephalitis


 

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