Vector-control programs that keep disease-spreading bugs at bay are suffering from the COVID-19 pandemic as resources are pulled from critical control programs and social distancing cuts down the reach of treatment areas, warned public health experts.
According to the World Health Organization, illness spread by vectors such as mosquitoes accounts for 17 percent of communicable disease in the world. Multiple major diseases are spread in this manner — including mosquitoes spreading malaria, dengue, yellow fever and Zika; flies spreading infection with Leishmania parasites, river blindness and sleeping sickness; ticks spreading Lyme disease; triatomine bugs spreading Chagas disease; and fleas spreading plague or typhus — accounting for 700,000 deaths annually worldwide.
Eighty percent of the world’s population is at risk from one or more vector-borne diseases, WHO says. The Centers for Disease Control and Prevention notes that North Americans are at risk of contracting Lyme, dengue fever, West Nile virus disease, Rocky Mountain spotted fever, plague, and tularemia, though pathogens not found in the United States such as chikungunya, Chagas disease, and Rift Valley fever are also threats as trade and travel occur and as climate change impacts vector populations and thus the geographical distribution of diseases.
A new report from the National Association of County and City Health Officials (NACCHO) says that while some programs have seen few adverse effects, the impact of the coronavirus has shut down some vector-control programs altogether heading into the summer or staff have been reassigned to confront the COVID-19 threat.
NACCHO compiled its findings on public-health departments’ current ability to address vector-borne threats during a time of “historically high vector-borne disease rates” after speaking with members of its Vector Control Collaborative and Vector Control Workgroup.
“As temperatures rise well above 50 degrees throughout much of the country, mosquito and tick populations increase, meaning many Americans are at a greater risk for vector-borne illness,” the report noted. “West Nile virus is the leading cause of domestically acquired mosquito-borne disease in the continental U.S. In 2018, 48 states and the District of Columbia (DC) reported 2,813 cases of domestic arboviral disease, including 2,647 (94%) West Nile virus disease cases. Other diseases, including eastern equine encephalitis, Jamestown Canyon, La Crosse, Powassan, and St. Louis encephalitis viruses, cause sporadic cases of disease and occasional outbreaks.”
“Shockingly, states that have experienced outbreaks in vector-borne disease in the past year have had their local vector programs deemed nonessential during the COVID-19 pandemic, halting surveillance and control activities that can detect or prevent vector-borne disease threats before they affect the community.”
NACCHO said vector-control programs they spoke with reported “varying levels of impact from COVID-19 to their routine operations, ranging from minimal impact to entire vector programs being deemed non-essential and shut down, or large portions of staff being realigned for COVID-19 response.”
The scaling back of programs or wholesale shutdowns have also impacted community outreach about preventing vector-borne illnesses and hampered the ability of departments to bring on temporary staff to confront seasonal threats.
The volume of COVID-19 cases and necessary testing is also taking lab capacity away from testing mosquito samples for potentially deadly pathogens, and the personal protective equipment vector-control personnel use — such as N-95 masks donned when spraying chemicals — are being used by personnel fighting COVID-19.
Social distancing is also eliminating face-to-face contact between public health officials and at-risk neighborhoods, leading departments to turn to mediums such as social media and radio to warn residents of vector-borne threats and mitigation strategies.
Departments are also having to decide where mosquito mapping is showing that they can likely do the most good with fewer resources, and focusing surveillance efforts on historically problematic areas.
“The COVID-19 response has taken time, attention, and personnel away from all other unrelated health priorities, as already underfunded and understaffed health departments respond to this pandemic,” said the NACCHO report. “In doing so, existing services are strained or paused, with health impacts that will ripple through communities.”