**Core Concept**
The World Health Organization (WHO) maintains a list of diseases under international surveillance, which are considered to be of public health concern due to their potential to cause significant morbidity, mortality, or economic burden. These diseases are monitored globally to facilitate early detection, prompt reporting, and coordinated response to outbreaks.

**Why the Correct Answer is Right**
Diseases under international surveillance include conditions such as poliomyelitis, measles, rubella, and yellow fever. These diseases are prioritized for surveillance due to their potential to spread rapidly across borders, particularly in areas with limited healthcare infrastructure. The WHO's International Health Regulations (IHR) require countries to report suspected cases of these diseases to the global health authority, enabling timely response and control measures.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect as it does not specify a disease under international surveillance. While some diseases may be subject to national surveillance, they may not be globally monitored.

**Option B:** This option is incorrect as it is a general term rather than a specific disease. While certain viral hemorrhagic fevers are considered public health threats, they are not necessarily under international surveillance.

**Option C:** This option is incorrect as it is a vaccine-preventable disease, but it is not among the priority diseases under international surveillance.

**Clinical Pearl / High-Yield Fact**
It is essential for healthcare providers to be aware of the diseases under international surveillance, as reporting suspected cases is crucial for preventing the spread of these conditions. Familiarity with the WHO's IHR and the list of prioritized diseases can help clinicians respond promptly and effectively to outbreaks.

**Correct Answer: D. Diseases such as poliomyelitis, measles, rubella, and yellow fever are under international surveillance.**