Bat-Borne and Rodent-Borne Viral Diseases

Question 1

Hantaviruses
(a) Family
(b) Order
(c) Genus
(d) Mode of transmission
(e) Basic structure and genome type

Answer 1

(a) Family: Hantaviridae
(b) Order: Bunyavirales
(c) Genus: Orthohantavirus
(d) Mode of transmission: contact with infected rodents and their excreta
(e) Basic structure and genome type: enveloped, three segments of negative-sense single stranded RNA viruses [Small (S) segment, Medium (M) segment, Large (L) segment]

[Diagram] [Diagram 2]

Question 2

Briefly state the role of each of the three segments of the Hantavirus genome.

Answer 2

🐀 Small (S) segment: Encodes the nucleocapsid protein (N protein), which is crucial for RNA encapsidation and protection.
🐀 Medium (M) segment: Encodes the glycoproteins (Gn and Gc), which are involved in virus attachment and entry into host cells.
🐀 Large (L) segment: Encodes the RNA-dependent RNA polymerase (RdRp), which is essential for viral RNA replication and transcription.
[Diagram 2]

Question 3

Name the two syndromes caused by Hantaviruses and state
(a) symptoms
(b) their respective regions of prevalence.

Answer 3

(1) Hantavirus Pulmonary Syndrome also calledHantavirus Cardiopulmonary Syndrome
Symptoms: fatigue, fever, muscle aches, coughing, shortness of breath, fluid build up in lungs, low blood pressure
Region of prevalence: Americas

(2) Hemorrhagic Fever with Renal Syndrome
Symptoms: intense headaches, back and abdominal pain, fever, chills, low blood pressure, acute shock, kidney failure
Region of prevalence: Europe, Asia

Question 4

Briefly discuss diagnosis and treatment of HPS and HFRS.

Answer 4

Hantavirus Pulmonary Syndrome
🐀 Diagnosis:
(1) Serology: Detection of hantavirus-specific IgM and IgG antibodies using enzyme-linked immunosorbent assay (ELISA).
(2) PCR: Polymerase chain reaction (PCR) to detect viral RNA in blood or tissue samples.
(3) Chest X-ray: To identify pulmonary edema and other lung abnormalities.

🐀 Treatment:
Treatment is supportive: oxygen therapy, mechanical ventilation, fluid management to prevent fluid overload and pulmonary edema.
[Some studies have explored the use of the antiviral drug ribavirin, but its effectiveness remains uncertain and it is not widely used.]

Hemorrhagic Fever with Renal Syndrome
🐀 Diagnosis:
(1) Serology: Detection of hantavirus-specific antibodies using ELISA.
(2) PCR: Detection of viral RNA in blood or tissue samples.
(3) Urinalysis and Blood Tests: To assess kidney function and detect signs of renal impairment.

🐀 Treatment is supportive: fluid management to maintain fluid and electrolyte balance, dialysis in case of acute kidney failure

Question 5

Briefly discuss prevention of Hantavirus infection.

Answer 5

🐀 Rodent control to reduce exposure to rodents and their excreta.
🐀 Encouraging proper hygiene practices, such as wearing gloves and masks when cleaning areas contaminated by rodents, can help prevent infection.

Question 6

List some bat-borne viruses.

Answer 6

Coronavirus, Rabies, Nipah, Ebola

Question 7

Ebola virus
(a) Family
(b) Genus
(c) Basic structure
(d) Genome type

Answer 7

(a) Family: Filoviridae
(b) Genus: Ebolavirus
(c) Basic structure: enveloped, helical
(d) Genome type: negative-sense, single-stranded RNA

[Diagram 1] [Diagram 2] [Diagram 3] [Image 1] [Image 2]

Question 8

Describe the pathogenesis of Ebola.

Answer 8

🛸 Transmission ⇒ Direct contact of mucosal membranes or broken skin with infected body fluids from animals/humans or infected fomites
🛸 Viral entry into mucosa or skin
🛸 The virus infects macrophages and dendritic cells, contributing to viremia ⇒ Systemic inflammation/infection ⇒ GI dysfunction and infection of endothelial cells/hepatocytes
🛸 DIC (Disseminated Intravascular Coagulation)/hemorrhage and hypotension ⇒ Shock and death
[7-minute video]: Ebola Virus (EVD) - Professor Dave Explains

Question 9

Briefly discuss the symptoms of Ebola Hemorrhagic Fever.

Answer 9

🩺 Early symptoms: Fever, fatigue, muscle pain, headache, and sore throat
🩺 Progressive symptoms: Vomiting, diarrhea, rash, and both internal and external bleeding

Question 10

List techniques used in the diagnosis of EVD.

Answer 10

(a) RT-PCR assay [preferably done within 48 hours of onset of symptoms]
(b) ELISA
(c) Antigen detection tests

Question 11

Briefly discuss prevention measures against Ebola Virus.

Answer 11

(1) Avoiding contact with infected individuals
(2) Wearing protective equipment when caring for patients or handling potentially contaminated materials.
(3) Hand hygiene
(4) Vaccination of contacts
(5) Safe burial practices
(6) Isolation and quarantine

Question 12

Besides Ebola, name one notable member of the genus Filoviridae that is known to cause hemorrhagic fever in humans.

Answer 12

Marburg virus

[Image 1] [Image 2] [Image 3] [Image 4] [Image 5]