Fewer mosquitoes could be flood's silver lining
Larvae washed away by water
While many are still counting their losses from the Flood of 2006, the region's top bug fighter is reporting one giant gain. The deluge apparently washed away much of the area's first batch of mosquitoes before they could sprout.
``These large wetlands areas with run off just spilled out everywhere and flushed out the mosquito larvae," said Walter Montgomery, superintendent of the Northeast Massachusetts Mosquito Control and Wetlands Management District. The agency tracks and kills mosquitoes in 29 area communities, including Haverhill and several others hardest hit by raging rivers and streams.
After last week's floods, teams were dispatched to assess the early mosquito population by skimming the surface of local ponds and marshes. They found far fewer larvae than would be expected in the midst of one of the rainiest Mays on record, according to Montgomery.
Officials in southern New Hampshire, which also bore the brunt of the flooding, are also not finding the expected level of larvae.
While extended periods of rain are often associated with a bumper crop of bugs, local mosquito specialists believe that so much rain fell that it has had the opposite effect in Northeastern Massachusetts -- at least for now.
The local findings appear to differ significantly from other areas of Massachusetts, where mosquito control officials have voiced concerns about a larger infestation following the rainfall. But not all regions are the same when it comes to bugs and breeding.
``The rainfall patterns were different throughout the state and there are differences in local habitats. They may have not gotten the same kind of flooding like we got up here," said Esteban Cuebas-Incle, an entomologist with the Northeast mosquito control district.
The spring began with an intense focus on beating back Eastern equine encephalitis, a mosquito-borne virus that killed two people in southern New Hampshire and two in Southeastern Massachusetts last summer. The district's spraying crews were sent out last month -- earlier than normal -- to target larvae in catch basins and storm drains in hopes of preventing more human infections.
Despite the early good news, officials remain on guard.
The greatest risk for human infections doesn't arrive until July or even later, when virus levels have built up in birds and mosquitoes. The disease is spread to humans when mosquitoes bite an infected bird, then bite a human.
The brood of bugs hatching now typically dies off before virus levels are worrisome, but not before they lay eggs that can help fuel mosquito populations later in the summer.
Weather conditions in coming weeks and months could also dramatically change the outlook. A prolonged period of dampness -- without raging flood waters -- could raise the alert levels again for Eastern equine encephalitis, also known as EEE.
However, the mosquitoes that typically carry West Nile virus, a less-lethal illness that travels between birds and humans, thrive after periods of drought.
EEE is fatal in roughly 30 percent of human cases, according to state health officials. Many who survive the disease have permanent disabilities. But EEE also is very rare, with just 83 cases recorded in Massachusetts since the virus was first detected in 1938.
While mosquito surveillance and control in Massachusetts is overseen by nine regional boards that cover more than half of the state's communities, the system across the border in New Hampshire is much more of a patchwork, with each community contracting for its own pest control and surveillance.
``That has been a challenge," said Jason Stull, New Hampshire's public health veterinarian.
Granite State officials went on the offensive last fall, in the wake of seven human cases of Eastern equine encephalitis, including the two deaths, and encouraged more communities to sign up for mosquito control, Stull said. Still, only 30 did, the majority in southern New Hampshire, which was a hot spot last year for encephalitis.
But right now, bug experts patrolling that turf are cautiously optimistic, Stull said.
``The entomologists I have spoken with believe a lot of the larvae and eggs were removed from the flooding, although it will create new habitats for the mosquitoes to survive, so it is difficult to predict," he said.
In Massachusetts, mosquito control crews are concerned about the North Shore's estimated 24,000 acres of area salt marshes, stretching from Salisbury through Essex, where the flood waters don't drain as quickly, allowing bugs to rapidly hatch in the shallow saltwater. Montgomery sent his teams out this week to spray the marshes with Bti, a bacterial spore that is designed to wipe out the larvae without harming other wildlife.
Kay Lazar can be reached at klazar@globe.com.
Northtalk
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