Which disease is primarily found in children under 10 years old and can be fatal?

La Crosse encephalitis is primarily associated with children under 10 years old and can lead to serious, and potentially fatal, complications. The disease is transmitted by mosquito bites, particularly from the Aedes triseriatus mosquito, which is more common in certain geographical areas.

One of the distinguishing features of La Crosse encephalitis is its significant impact on pediatric populations, as children are more susceptible to the virus than adults. Symptoms in infected children can include fever, headache, vomiting, and more severe neurological symptoms that may advance to encephalitis, resulting in long-term health issues or death.

In the context of the other diseases listed, while West Nile Virus and St. Louis encephalitis can affect individuals of all ages, they do not exhibit the same specific vulnerability in children under 10. Dog heartworm is a condition that primarily affects dogs, and while it can have serious consequences, it does not directly impact human health in the same way. Therefore, La Crosse encephalitis stands out for its specific association with younger children and the heightened risks it poses to this age group.