Mosquitoes and Ticks and Fleas, Oh My!

“Disease cases from mosquito, tick, and flea bites tripled in the US from 2004 to 2016,” according to the CDC, with over 640,000 cases reported. They are blunt in their assessment that the U.S. is currently ill prepared to deal with vector borne diseases. State and local health departments, which the CDC notes are critical in controlling these diseases, are chronically underfunded.

Dr. Lyle R. Petersen, the agency’s director of vector-borne diseases, says that “the numbers on some of these diseases have gone to astronomical levels,” and that “the real case numbers were undoubtedly far larger.” He explains there are several factors at play:

“Ticks thriving in regions previously too cold for them, and hot spells triggering outbreaks of mosquito-borne diseases. Other factors include expanded human travel, suburban reforestation and a dearth of new vaccines to stop outbreaks…A recent survey of mosquito control agencies found that 84 percent needed help with such basics as surveillance and testing for resistance to pesticides”

A handful of super fun tick-borne diseases: Lyme disease, Anaplasmosis, Babesiosis, Rocky Mountain Spotted Fever, Powassan virus, and Tularemia.

For the mosquito lovers, there’s Chikungunya, Dengue, Eastern equine encephalitis, West Nile virus, Yellow fever, Zika, and malaria.

As you should know from reading this blog, the best known disease caused by fleas: the Plague.

Dengue Vaccine Gone Wrong?

A Dengue vaccine program was recently suspended in the Philippines due to concerns that the “vaccine could worsen the potentially deadly disease in people not previously infected.” The vaccine, known as Dengvaxia, has been given to over 830,000 children. It’s the first-ever approved dengue vaccine, produced by the French pharmaceutical company Sanofi. While it appears to be effective in people who have already had the virus, given the results of the study, the vaccine program has been suspended pending a review.

Dengue is an infection caused by mosquitoes. It’s a flu like illness found in tropical and sub-tropical climates and can be deadly. It’s the leading cause of serious illness and death among children in these areas. Infection rates have grown globally in recent decades and half the worlds’ population is at risk. Early detection and access to proper medical care dramatically lowers fatality rate.

Did a researcher foresee this problem?

Four decades ago, Dr. Scott Halstead, a leading figure in dengue research, first proposed that antibodies from an initial exposure to one of four types of the disease could increase the risk of a potentially lethal complication called severe dengue when a person was infected a second time, a process know as antibody-dependent enhancement or ADE.

This phenomenon could make development of a dengue vaccine tricky.

Rather than being protective, a shot given to someone who had never had dengue could act like a first infection, increasing their risk of severe dengue when they were exposed a second time.