Why smallpox to eradicate easier than measles?

Smallpox has been eradicated easier than measles due to several factors:

1. Disease characteristics: Smallpox is a highly contagious disease, but it is not as easily transmitted as measles. Measles is an extremely contagious disease that is spread through respiratory droplets, making it more challenging to control.

2. Vaccination: The development of an effective vaccine played a crucial role in eradicating smallpox. The smallpox vaccine was widely used and provided strong immunity, leading to a significant decrease in the number of cases. Conversely, the measles vaccine, while effective, has faced challenges related to vaccine hesitancy and lower vaccination rates in certain populations.

3. Transmission dynamics: Smallpox has a longer incubation period compared to measles. This longer period allows for more effective isolation of infected individuals, preventing further transmission. In contrast, measles has a shorter incubation period and can spread rapidly before symptoms appear.

4. Surveillance and containment: The eradication of smallpox was achieved through a comprehensive global effort, with strong surveillance systems in place. This enabled the quick identification and containment of outbreaks, including ring vaccination campaigns to prevent the spread of the disease. Measles eradication has been more challenging due to the lack of global coordination and challenges in maintaining high vaccination coverage in all regions.

5. Natural immunity: Smallpox infection provides long-lasting immunity, preventing re-infection. As a result, once vaccinated individuals develop immunity, they are less likely to spread the disease, reducing the pool of susceptible individuals. In the case of measles, while the vaccine provides immunity, there have been documented cases of breakthrough infections, where vaccinated individuals can still contract and transmit the disease.

6. Lack of animal reservoirs: Smallpox is a human-only disease, meaning that it does not have any animal reservoirs. This simplifies eradication efforts as the virus transmission is limited to human populations. In contrast, measles can infect both humans and certain animal species, making eradication more challenging.

In summary, the combination of factors such as vaccination effectiveness, disease characteristics, transmission dynamics, surveillance and containment, and lack of animal reservoirs made it easier to eradicate smallpox compared to measles.