Congenital Viral Infections

Congenital, Perinatal, and Neonatal Viral Infections

Intrauterine• Rubella• CMV• HSV• VZV• HIV• HTLV-1• Hepatitis B • Hepatitis C• Parvovirus B19• Lassa Fever• Japanese Encephalitis

Perinatal and Neonatal• HSV• VZV• HIV• HTLV-1• Hepatitis B• Hepatitis C

Arthropod-borne Viruses (Arboviruses)

Are viruses that can be transmitted to man by arthropod vectors

Arthropod Vectors

MosquitoesDengue, yellow fever

TicksCrimean-Congo haemorrhagic fever

SandfliesRift valley fever

Examples of Arthropod Vectors

Phlebotmine SandflyCulex Mosquito

Assorted TicksAedes Aegypti

Dengue Fever

• The biggest arbovirus problem in the world today with over 2 million cases per year

• Dengue is found in SE Asia, Africa and S America.

• Transmitted by Aedes mosquitoes residing in water-filled containers.

• Transmission cycle: human-mosquitoe-human

Distribution of Dengue

• High fever, lymphadenopathy, myalgia, bone and joint pains, headache, and a maculopapular rash.

• Severe cases may present with haemorrhagic fever and shock with a mortality of 5-10%. (Dengue haemorrhagic fever or Dengue shock syndrome)

Dengue Fever

Dengue Haemorrhagic Fever

Dengue Fever

• Diagnosis : by serology.• Treatment: no specific antiviral therapy.• Prevention

Mosquito eradication. Removal of all containers from premises which

may serve as vessels for egg deposition. A live attenuated vaccine is being tried in

Thailand with encouraging results.

Viral Zoonosis

Rabies Virus

Structure of rabies virus

(CDC)

• Characteristic bullet-shaped appearance

• ssRNA enveloped virus

Epidemiology

• Rabies is a zoonosis which is prevalent in wildlife. • The animals involved differ from continent to continent.• Wide range of hosts: fox, bats wolf dog

Rabies: Pathogenesis

Rabid animals become aggressive

and harbor the virus in saliva

Rabies: Clinical Features

• Incubation Period depends on: Infective dose Site of animal bite

• Prodromal Period (up to two weeks) Pain or itching at the site of the wound, Fever & headache.

• CNS infection (Neurological phase) Hydrophobia in half of the patients. Seizures and hallucinations. Paralysis leading to respiratory failure Coma & death

Laboratory Diagnosis

Histopathology (Negri Bodies)• Are pathognomonic of rabies • Are intracytoplasmic inclusions

formed by aggregates of nucleocapsids in neurons of about 90% of infected humans

Negri Body in neuron cell (CDC)

Rapid virus antigen detection

Positive DFA test (CDC

Laboratory Diagnosis

Virus Cultivation

Serology

Management and PreventionPre-exposure Prophylaxis • Inactivated rabies vaccine to high risk persons like vets,

animal handlers, laboratory workers etc.

Post-exposure Prophylaxis • In cases of animal bites, dogs and cats in a rabies endemic

area should be held for 10 days for observation. If signs develop, they should be killed and their tissue examined.

• Local treatment of wounds• Passive immunization - human rabies immunoglobulin • Active immunization - the human diploid cell vaccine is

usually administered into the deltoid region, and 5 doses are usually given.

Established Rabies• Nothing much can be done except

intensive supportive care.

• To date, only 2 persons with proven rabies have survived.

Management and Prevention

Control of Rabies

• Urban - canine rabies: 99% of all human rabies. – Dog control– Vaccination of dogs – Quarantine of imported animals

• Wildlife - much more difficult to control.

• G Protein (Surface glycoprotein) – Binds to cellular receptors and is the target of

neutralizing antibodies• M (matrix) protein.

– This is a peripheral membrane protein may act as a bridge between the membrane or G protein and the nucleocapsid.

• N (Nucleoprotein) protein– This is the major structural protein that covers

the RNA genome and protects it from nucleases. • L (Large) protein

– Its gene takes up 60% of the genome• P (phospho)) protein

Rabies Virus Proteins