Viral Infections
Dengue Fever
Aedes-borne viral illness with fever, thrombocytopenia, plasma leakage
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Chikungunya
Acute febrile viral illness transmitted by Aedes mosquitoes, characterized by severe polyarthralgia.
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Varicella :: (Chickenpox)
Highly contagious primary infection caused by Varicella-Zoster Virus (VZV).
Characterized by successive crops of pruritic vesicles (“dew-drop on a rose petal”).
Transmitted by airborne droplets and direct contact; seasonal peaks in late winter–spring.
After primary infection, VZV becomes latent in dorsal root ganglia and can reactivate later as Herpes Zoster.
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Characterized by successive crops of pruritic vesicles (“dew-drop on a rose petal”).
Transmitted by airborne droplets and direct contact; seasonal peaks in late winter–spring.
After primary infection, VZV becomes latent in dorsal root ganglia and can reactivate later as Herpes Zoster.
Rubeola :: Measles
Measles (Rubeola) is a highly contagious acute febrile illness caused by the Measles virus (genus Morbillivirus, family Paramyxoviridae).
Transmission occurs via respiratory droplets and airborne spread, with a 90% infection rate among susceptible contacts.
It presents with fever, cough, coryza, conjunctivitis, followed by a maculopapular rash and is preventable by the MMR vaccine.
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Transmission occurs via respiratory droplets and airborne spread, with a 90% infection rate among susceptible contacts.
It presents with fever, cough, coryza, conjunctivitis, followed by a maculopapular rash and is preventable by the MMR vaccine.
Rubella ::German Measles
*Rubella is a mild viral exanthem caused by Rubella virus*
*Infection during pregnancy can cause severe congenital defects (CRS)*
Rubella is an acute, generally mild viral infection caused by a Togavirus (Rubella virus).
It presents with low-grade fever, tender postauricular and suboccipital lymphadenopathy, and a faint pink maculopapular rash lasting 1–3 days.
While illness is usually mild in children and adults, **maternal infection in early pregnancy can lead to congenital rubella syndrome (CRS)**, causing serious fetal abnormalities.
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*Infection during pregnancy can cause severe congenital defects (CRS)*
Rubella is an acute, generally mild viral infection caused by a Togavirus (Rubella virus).
It presents with low-grade fever, tender postauricular and suboccipital lymphadenopathy, and a faint pink maculopapular rash lasting 1–3 days.
While illness is usually mild in children and adults, **maternal infection in early pregnancy can lead to congenital rubella syndrome (CRS)**, causing serious fetal abnormalities.
Mumps
*Mumps is an acute viral illness caused by the mumps virus (a Paramyxovirus), primarily affecting the salivary glands — especially the parotid glands.*
It spreads via respiratory droplets and has a high attack rate in unvaccinated populations.
Complications include orchitis, meningitis, sensorineural hearing loss, and pancreatitis.
Widespread vaccination (MMR) has drastically reduced global incidence.
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It spreads via respiratory droplets and has a high attack rate in unvaccinated populations.
Complications include orchitis, meningitis, sensorineural hearing loss, and pancreatitis.
Widespread vaccination (MMR) has drastically reduced global incidence.
Herpes Zoster / Shingles
Herpes zoster (shingles) is a painful vesicular rash caused by reactivation of latent Varicella-Zoster Virus (VZV) residing in sensory dorsal root or cranial nerve ganglia.
It presents as a unilateral, dermatomal eruption preceded by burning or neuropathic pain.
The disease primarily affects older adults and immunocompromised individuals and can lead to post-herpetic neuralgia, a chronic pain syndrome.
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It presents as a unilateral, dermatomal eruption preceded by burning or neuropathic pain.
The disease primarily affects older adults and immunocompromised individuals and can lead to post-herpetic neuralgia, a chronic pain syndrome.
Influenza (A/B/C)
Acute contagious respiratory viral illness caused by Orthomyxoviridae (Influenza A, B, C).
Characterised by abrupt high fever, severe myalgia, headache, and cough.
Influenza A causes epidemics & pandemics; B causes outbreaks; C causes mild disease.
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Characterised by abrupt high fever, severe myalgia, headache, and cough.
Influenza A causes epidemics & pandemics; B causes outbreaks; C causes mild disease.
Zika Virus Infection
A mosquito-borne flavivirus infection characterized by mild fever, rash, arthralgia, and conjunctivitis.
While illness is usually mild in adults, Zika is strongly linked to congenital Zika syndrome, microcephaly, and other fetal abnormalities.
Transmission occurs via Aedes mosquitoes, sexual contact, blood transfusion, and vertical transmission.
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While illness is usually mild in adults, Zika is strongly linked to congenital Zika syndrome, microcephaly, and other fetal abnormalities.
Transmission occurs via Aedes mosquitoes, sexual contact, blood transfusion, and vertical transmission.
Respiratory Syncytial Virus
RSV (Respiratory Syncytial Virus) is a common contagious virus that causes lower-respiratory tract infections, especially in infants, young children, and older adults.
It is the leading cause of bronchiolitis and pneumonia in infants worldwide.
Most infections are mild, but severe disease occurs in premature infants, those with congenital heart/lung disease, immunocompromised adults, and the elderly.
Key features: seasonal outbreaks, high reinfection rates, and significant hospitalization burden in children <2 years.
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It is the leading cause of bronchiolitis and pneumonia in infants worldwide.
Most infections are mild, but severe disease occurs in premature infants, those with congenital heart/lung disease, immunocompromised adults, and the elderly.
Key features: seasonal outbreaks, high reinfection rates, and significant hospitalization burden in children <2 years.
Adenovirus Infection
Adenoviruses are non-enveloped double-stranded DNA viruses causing respiratory illness, conjunctivitis, gastroenteritis, and hemorrhagic cystitis.
Transmission occurs through respiratory droplets, fecal–oral spread, and contaminated surfaces/swimming pools.
Most infections are mild and self-limited but severe disease can occur in neonates and immunocompromised patients.
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Transmission occurs through respiratory droplets, fecal–oral spread, and contaminated surfaces/swimming pools.
Most infections are mild and self-limited but severe disease can occur in neonates and immunocompromised patients.
Erythema Infectiosum ("fifth disease")
*Parvovirus B19 causes erythema infectiosum (“fifth disease”), a common childhood exanthem.*
It primarily infects erythroid precursor cells → temporary suppression of red cell production.
Classic “slapped-cheek rash” appears after mild prodrome; disease is usually self-limited.
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It primarily infects erythroid precursor cells → temporary suppression of red cell production.
Classic “slapped-cheek rash” appears after mild prodrome; disease is usually self-limited.
COVID-19
19 identified in Wuhan, China (2019) as a cluster of viral pneumonia
Caused by a novel coronavirus later named SARS-CoV-2
Declared a global pandemic by WHO in March 2020
One of the most significant infectious disease events of modern medical history
Named as:
• CO = Corona
• VI = Virus
• D = Disease
• 19 = Year 2019
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Caused by a novel coronavirus later named SARS-CoV-2
Declared a global pandemic by WHO in March 2020
One of the most significant infectious disease events of modern medical history
Named as:
• CO = Corona
• VI = Virus
• D = Disease
• 19 = Year 2019
Parainfluenza
Parainfluenza virus infection is an acute respiratory illness caused by Human Parainfluenza Viruses (HPIV 1–4)
• Family: Paramyxoviridae
• Genus: Respirovirus / Rubulavirus (depending on type)
• RNA virus (enveloped, negative-sense ssRNA)
• Common in infants and young children
• Major cause of croup (laryngotracheobronchitis)
“Parainfluenza” means clinically similar to influenza but virologically different.
Unlike influenza (Orthomyxoviridae), parainfluenza belongs to Paramyxoviridae and does not undergo antigenic shift like influenza.
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• Family: Paramyxoviridae
• Genus: Respirovirus / Rubulavirus (depending on type)
• RNA virus (enveloped, negative-sense ssRNA)
• Common in infants and young children
• Major cause of croup (laryngotracheobronchitis)
“Parainfluenza” means clinically similar to influenza but virologically different.
Unlike influenza (Orthomyxoviridae), parainfluenza belongs to Paramyxoviridae and does not undergo antigenic shift like influenza.
Human Metapneomovirus
Name: Human metapneumovirus (hMPV)
Category: Infectious Diseases
Subcategory: Viral Infections → Respiratory viruses
About the name / discovery
• Identified in 2001 in the Netherlands.
• Belongs to Paramyxoviridae family, closely related to RSV.
• “Metapneumovirus” → indicates virus related to pneumoviruses but genetically distinct from classical RSV lineage.
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Category: Infectious Diseases
Subcategory: Viral Infections → Respiratory viruses
About the name / discovery
• Identified in 2001 in the Netherlands.
• Belongs to Paramyxoviridae family, closely related to RSV.
• “Metapneumovirus” → indicates virus related to pneumoviruses but genetically distinct from classical RSV lineage.