Disease cases in the US from mosquito, tick, and flea bites, 2004-2016. Disease cases from mosquito, tick, and flea bites tripled in the US from 2004 to 2016. Graphic: Rosenberg, et al., 2018 / CDC Vital Signs

1 May 2018 (E360 Digest) – The number of people in the United States infected by mosquito, tick, and flea-transmitted diseases have tripled, increasing from 27,388 cases in 2004 to 96,075 in 2016, according to a new report from the Centers for Disease Control. Since 2004, nine insect-borne diseases have also been discovered or introduced into the U.S., seven of which are carried by ticks.

In total, more than 640,000 cases of mosquito, tick, and flea-borne diseases were reported to the CDC between 2004 and 2016. Infections spiked in 2016, increasing 73 percent from 2015, due to the Zika epidemic. Cases of Lyme disease doubled from 2004, with 36,429 reported cases in 2016. Lyle R. Petersen, the CDC’s director of vector-borne diseases, however, told The New York Times the numbers for Lyme are likely far larger. The CDC estimates 300,000 Americans that get Lyme disease every year, nearly 10 times the number of diagnoses reported.

The new report does not mention climate change or global warming, but Petersen told Reuters that warmer, shorter winters have helped boost the populations of ticks, mosquitos, and other disease-carrying insects in recent years. “It enables these ticks to expand to new areas. Where there are ticks, there comes diseases,” he said. In addition, increasing summer temperatures and heavy rain events that leave behind standing pools of water encourage mosquito breeding. Other factors include increases in the number of people traveling internationally, suburban reforestation, and a lack of new vaccines being developed.

U.S. Infections from Tick, Fleas, and Mosquito Bites Have Tripled

Disease cases in the U.S. from ticks, 2004-2016. Graphic: Rosenberg, et al., 2018 / CDC Vital Signs

By Donald G. McNeil Jr.
1 May 2018

(MSN) – The number of people who get diseases transmitted by mosquito, tick, and flea bites has more than tripled in the United States in recent years, federal health officials reported Tuesday. Since 2004, at least nine such diseases have been newly discovered or introduced into the United States.

Warmer weather is an important cause of the surge in cases reported to the Centers for Disease Control and Prevention, according to the lead author of a study in the agency’s Morbidity and Mortality Weekly Report.

But the author, Dr. Lyle R. Petersen, the agency’s director of vector-borne diseases, repeatedly declined to connect the increase to the politically fraught issue of climate change, and the report does not mention either climate change or global warming.

Many other factors are at work, he emphasized, while noting that “the numbers on some of these diseases have gone to astronomical levels.”

CDC officials called for more support for state and local health departments. Local agencies “are our first line of defense,” said Dr. Robert Redfield, the CDC’s new director. “We must enhance our investment in their ability to fight these diseases.”

Although state and local health departments get brief infusions of cash during scares like the 2016 Zika epidemic, they are chronically underfunded. A recent survey of mosquito control agencies found that 84 percent needed help with basics like surveillance and pesticide-resistance testing, Petersen said.

While the CDC did not suggest that Americans drop plans for playing outdoors or resting in hammocks this summer, Redfield emphasized that everyone — especially children — needed to protect themselves against tick and mosquito bites.

Between 2004 and 2016, about 643,000 cases of 16 insect-borne illnesses were reported to the CDC — 27,000 a year in 2004, rising to 96,000 by 2016. (The year 2004 was chosen as a baseline because the agency began requiring more detailed reporting then.)

The real case numbers were undoubtedly far larger, Petersen said. For example, the CDC estimates that about 300,000 Americans get Lyme disease each year, but only about 35,000 diagnoses are reported.

The study did not delve into the reasons for the increase, but Petersen said it was probably caused by many factors, including two related to weather: Ticks thriving in regions previously too cold for them, and hot spells triggering outbreaks of mosquito-borne diseases. Other factors, he said, include expanded human travel, suburban reforestation and a dearth of new vaccines to stop outbreaks.

In an interview, Petersen said he was “not under any pressure to say anything or not say anything” about climate change and that he had not been asked to keep mentions of it out of the study. [more]

Tick and mosquito infections are spreading rapidly, CDC finds

ABSTRACT: Vectorborne diseases are major causes of death and illness worldwide. In the United States, the most common vectorborne pathogens are transmitted by ticks or mosquitoes, including those causing Lyme disease; Rocky Mountain spotted fever; and West Nile, dengue, and Zika virus diseases. This report examines trends in occurrence of nationally reportable vectorborne diseases during 2004–2016.

Methods: Data reported to the National Notifiable Diseases Surveillance System for 16 notifiable vectorborne diseases during 2004–2016 were analyzed; findings were tabulated by disease, vector type, location, and year.

Results: A total 642,602 cases were reported. The number of annual reports of tickborne bacterial and protozoan diseases more than doubled during this period, from >22,000 in 2004 to >48,000 in 2016. Lyme disease accounted for 82% of all tickborne disease reports during 2004–2016. The occurrence of mosquitoborne diseases was marked by virus epidemics. Transmission in Puerto Rico, the U.S. Virgin Islands, and American Samoa accounted for most reports of dengue, chikungunya, and Zika virus diseases; West Nile virus was endemic, and periodically epidemic, in the continental United States.

Conclusions and Implications for Public Health Practice: Vectorborne diseases are a large and growing public health problem in the United States, characterized by geographic specificity and frequent pathogen emergence and introduction. Differences in distribution and transmission dynamics of tickborne and mosquitoborne diseases are often rooted in biologic differences of the vectors. To effectively reduce transmission and respond to outbreaks will require major national improvement of surveillance, diagnostics, reporting, and vector control, as well as new tools, including vaccines.

Trends in Reported Vectorborne Disease Cases — United States and Territories, 2004–2016


  1. Dennis Mitchell said...

    More scary stuff.  


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