Identify the odd one out
Nipah
Covid-19
Small Pox
Rabies
Smallpox is the odd one out among Nipah, COVID-19, Smallpox, and Rabies because it is the only disease officially eradicated worldwide by the WHO in 1980 through vaccination campaigns. The others remain active threats with ongoing cases and no eradication.
Disease Overviews
Nipah virus causes severe encephalitis and respiratory illness, transmitted mainly from fruit bats via contaminated food or date palm sap, with limited human-to-human spread through saliva. COVID-19, caused by SARS-CoV-2, spreads primarily through respiratory droplets and aerosols, leading to global pandemic with high transmissibility. Smallpox, from variola virus, spreads person-to-person via droplets or contact with lesions, producing characteristic rash and high fever. Rabies, caused by lyssavirus, transmits almost exclusively through animal bites via saliva, progressing to fatal encephalitis without prompt treatment.
Key Differences
| Disease | Causative Agent | Primary Transmission | Vaccine Status | Eradication Status |
|---|---|---|---|---|
| Nipah | Nipah virus (Paramyxoviridae) | Zoonotic (bats), limited human-to-human | In trials, none approved | Not eradicated |
| COVID-19 | SARS-CoV-2 (Coronaviridae) | Respiratory droplets/aerosols | Multiple approved worldwide | Not eradicated |
| Smallpox | Variola virus (Poxviridae) | Person-to-person droplets/contact | Available, key to eradication | Eradicated 1980 |
| Rabies | Rabies virus (Rhabdoviridae) | Animal bites/saliva | Approved for pre/post-exposure | Not eradicated |
Why Smallpox is Odd
Smallpox eradication succeeded due to its human-only host, effective vaccine, and global ring vaccination strategy that interrupted transmission. Nipah, COVID-19, and Rabies persist due to animal reservoirs (bats/dogs) enabling re-emergence, despite vaccine progress. This distinction highlights eradication feasibility in virology for exams like CSIR NET Life Sciences.
