HAVERHILL — The city will spray this week for mosquitoes for the third time this month after an Essex County man in his 60s was diagnosed with the county’s first human case of West Nile virus this year.
The state Department of Public Health announced the human case Tuesday, but has declined to identify the man’s hometown. He was treated and released from a hospital and is expected to be OK, state health officials said.
The local human case of West Nile virus is the fourth reported case in Massachusetts this year.
“The epidemiological investigation conducted by DPH indicates that the patient was most likely exposed to infected mosquitoes in Essex County,” the public health agency said in a press release. “This area is already considered to be at moderate risk from West Nile virus and will remain at that level.”
As a result, Mayor James Fiorentini said he ordered mosquito control spraying this week in selected parts of the city. He said spraying will take place as soon the temperature goes over 50 degrees, because mosquito-killing chemicals are not effective in cool weather.
David Van Dam, the mayor’s aide, said tonight or Friday look to be the most likely days when spraying will take place, based on weather reports.
Haverhill last sprayed Sept. 19 and before that during the first week this month.
The mayor said residents will be notified when their neighborhood is about to be sprayed by the city’s emergency call system, Blackboard Connect.
The spraying will be take place from the back of spray trucks with “the standard Duet solution.” Fiorentini said the city is also continuing its ban on nighttime school and recreation activities.
The city’s Board of Health is recommending a number of precautionary measures, such as using insect repellent, wearing long sleeves and long pants, and avoiding outdoor activities from dusk to dawn.
The mayor said residents are urged to check their properties for unattended containers of standing water that might attract mosquitoes. The local Health Department along with the Northeast Mosquito Control Program will continue to monitor and test Haverhill for disease-carrying mosquitoes, Fiorentini said.
While West Nile virus can be fatal, the majority of people infected show no symptoms.
According to a Massachusetts Department of Public Health fact sheet, West Nile virus is a mosquito-carried virus that can cause illness ranging from a mild fever to more serious disease like encephalitis or meningitis. There is no specific treatment for the virus. People with mild infections usually recover on their own. People with severe infections almost always require hospitalization. Their symptoms may last several weeks and neurological effects may be permanent. About 10 percent of people who develop severe illness die from the infection.
This summer, mosquitoes from Groveland, Methuen, Haverhill and many other communities in the area have tested positive for West Nile virus or Eastern equine encephalitis.
Last year, 33 cases of West Nile virus were reported in Massachusetts residents, according to state officials. Essex County had two human cases of Eastern equine encephalitis, or EEE, last year, but no West Nile virus.
“This (Essex County) case underscores the fact that mosquito-borne illness remains a threat in Massachusetts and will continue to be until the first hard overnight frost,” the state press release said.
More information, including all Werst Nile virus and EEE positive results from 2013, can be found at www.mass.gov/dph/mosquito.
For more information about Northeast Mosquito Control and Wetlands Management District, visit www.northeastmassmosquito.com.