Question

Why in recent years has there been an increase in cases of Powassan transmission? What changes in the virus or vector have occurred? What are the symptoms of infection?

Answer 1

Answer:

The Powassan is a virus (flavivirus), transmitted by deer ticks. It does not require the tick to remain attached for very long for transmitting the infection (within an hour). Increase in cases may be due to the following :

a. Maybe it driven by increases in the virus population size, as it is well-documented expansion in the population of deer ticks that has occurred in recent decades, accordingly increased the population size, of their pathogens.

b. This recent increase maybe due to the people encroaching on natural environments and disrupting ecology (population dynamics).

Ticks rely upon one, two three-hosts to complete their lifecycle. There are two discrete lineages of POWV that have been found i.e. lineage I is the POWV and lineage II is the DTV. POWV is maintained in nature by ixodid ticks and mammalian hosts.The common tick causing Powassan disease goes through a three-host lifecycle. The first host of the vector during the larvae stage is rodent , then bird in the nymph stage. Final stage on a “larger herbivore, carnivore, or human.

Symptoms of infection are following:

1. Fever, fatigue, nausea and vomiting

2. Maculopapular rash on the chest

3. Blurry vision, diplopia, nystagmus and upward gaze

4. Hemiparesis and hemiplegia

5. Spastic and flaccid paralysis

6. Dizziness, confusion and depression