More Reasons Why Smart People Don’t Build Near Wetlands: Mosquitoes and Disease

[7/26/07 clarification:

In the article below, we don’t mean to imply
that dengue/malaria/yellow fever are currently in Northampton. However, they
serve to illustrate that mosquitoes are associated with disease in general (such as West Nile Virus and Eastern Equine Encephalitis), and
that excessively exposing people to mosquitoes is risky.

As the New
England climate has been getting warmer in recent decades (for whatever
reason), it is conceivable that problems associated with more tropical zones will become more common here. For example, last month the Boston Globe reported
how the woolly adelgid has been steadily advancing
north and killing trees since New England winters have become less cold. Since
we’re talking about long-term issues like where to site houses, we believe that
taking the long view is appropriate.

For over 350 years, Northampton builders have chosen to avoid the wetlands and buffer areas that Kohl Construction is proposing to encroach upon. We believe their wisdom should not be casually tossed aside in the name of today’s hot planning craze, namely infill.]

So far we have emphasized environmental concerns and flood mitigation as reasons why it’s unwise to build within 100 feet of wetlands. There’s another major reason–health–as America’s earliest settlers quickly discovered:

Perhaps the first Virginians to succumb to the ravages
of infectious disease were the settlers at Jamestown.
Mosquito-borne yellow fever and malaria took its toll
on the colony’s first generation. Eighty percent
of the 6,000 settlers sent to Jamestown between 1607
and 1625 died from disease, starvation, Indian attack
or other causes…

The spread of epidemic diseases in Virginia and the
rest of the nation was closely related to social,
economic and geographical conditions, reports The
Reader’s Companion to American History
… Jamestown’s
location on low, mosquito-ridden land was a breeding
ground for disease…

Anyone who has walked around the wetlands between North Street and the bike trail can attest to its large numbers of mosquitoes in the warmer months. Kohl Construction proposes to locate 31 condo units bordering these wetlands. The American Mosquito Control Association notes the dangers of bringing people and animals into close contact with large numbers of mosquitoes.

Mosquitoes cause more human suffering than any other organism — over
one million people die from mosquito-borne diseases every year. Not
only can mosquitoes carry diseases that afflict humans, they also
transmit several diseases and parasites that dogs and horses are very
susceptible to. These include dog heartworm, West Nile virus (WNV) and
Eastern equine encephalitis (EEE). In addition, mosquito bites can
cause severe skin irritation through an allergic reaction to the
mosquito’s saliva – this is what causes the red bump and itching.
Mosquito vectored diseases include protozoan diseases, i.e., malaria, filarial diseases such as dog heartworm, and viruses such as dengue, encephalitis and yellow fever.

Environmental Health Perspectives observes that forest clearance and wetlands drainage can have complex effects on mosquito populations. Siting homes and their associated paraphernalia next to mosquito breeding areas, however, is clearly unwise. Kohl’s five planned detention pools are particularly troubling as potential breeding sites.

Human activities are also crucial to transmission [of disease]. Forest clearance
eliminates species that breed in water in tree holes (e.g., the forest Aedes species
that transmit yellow fever) but provides favorable conditions for those
that prefer temporary ground pools exposed to full sunlight (e.g., many
of the Anopheles species that transmit malaria). Drainage of
wetlands eliminates the marshy pools exploited by many species but can
provide the open channels preferred by others (e.g., some important
European vectors of malaria, and Culex tarsalis, a vector of
St. Louis encephalitis). Agricultural fertilizers can promote the
growth of algae and other larval nutrients, whereas herbicides may
eliminate them altogether. Cisterns, pit latrines, sewage-polluted
ditches, storm drains, and blocked gutters can support large
populations of Cx. quinquefasciatus, an important vector of
Bancroftian filariasis. Wells are often a significant source of malaria
vectors. Water-storage jars and drums, cemetery urns, discarded rubber
tires, buckets, pots, and other man-made containers can be prolific
sources of Ae. aegypti, an important peridomestic vector of yellow fever and dengue and other species that originally bred in tree holes.

Additional factors arise from behavior and cultural traits. Daily
activity patterns–work, rest, and recreation–the location of homes in
relation to mosquito breeding sites, the design of buildings, the
materials used to build them, the use of screens and bed nets, and many
other factors can be significant…

Forest clearance. Many important malaria vectors breed in
open sunlit pools. Forest clearance provides abundant new habitat for
these species and is a classic cause of the emergence of malaria
problems (110)…

Urbanization. In rapidly expanding urban areas, extensive water
storage and inadequate water disposal can lead to disastrously high
mosquito populations. The absence of cattle can promote stable
transmission by forcing zoophilic species to feed on people.

Many tropical cities are surrounded by large satellite settlements that
retain rural characteristics. Their dense populations promote
conditions that are ideal for transmission. Infection rates in these
semirural habitats are often higher than in the cities themselves…

Factors that Influence Yellow Fever Transmission

Urbanization. The rapid growth of densely populated towns and
cities throughout the tropics provides an increasingly favorable
environment for epidemic transmission. Even when piped water is
available, the supply is often intermittent, so reserves of water are
stored in containers that are a source of Ae. aegypti. Other
artifacts–buckets, flowerpots, bottles, cans, defunct household
appliances, discarded tires, and many other items–can also serve as
breeding sites if they accumulate rainwater…

Dengue [this discussion underscores that increasing urban density carries risks]

…Layout of cities. The layout of modern U.S. cities is based on
the automobile. Population density is relatively low. Housing areas are
often discrete, interspersed with shopping precincts, industrial parks,
and other nonresidential land. Much space is devoted to wide roads,
parking lots, and other open areas. Plot sizes are large, and the
spacing between houses is often greater than in many tropical cities.
The number of persons per house is smaller because couples have fewer
children, and the extended family is less prevalent. All these factors
limit the number of humans that are accessible to mosquitoes, thereby
reducing the likelihood of epidemic transmission…

Kohl Construction condo proposal showing detention pools and proximity to wetlands:

See also:

Gazette: “West Nile buzzing in the city: Mosquito tests positive for virus in Northampton” (8/21/08)
…The DPH announced Wednesday afternoon that a mosquito trapped in Northampton on Sunday, Aug. 17, has tested positive for West Nile. The test comes on the heels of a host of positive West Nile tests in mosquitoes and crows in several communities throughout the month of July and August…

…for the first time this week the state has confirmed a positive mosquito sample of eastern equine encephalitis in the town of Carver…

[West Nile] can be fatal to humans – some 124 people in the United States died from it last year, according to the National Institutes of Health…

Aedes vexans [emphasis added]
Aedes vexans can be found in many different
habitats. Among these are: open rain pools, tire ruts, stormwater
management facilities (this includes detention, retention and
infiltration basins)
, dredge spoil sites, salt marsh impoundments,
ditches, areas in which streams or creeks have flooded over their
banks, flooded woodlands, around the edges of semi-permanent swamps
and bogs that are subject to some drying down, and woodland pools
or any type of temporary rain pool. Larvae do not seem to exhibit
a marked preference for either sunlight or shade within these
habitats. Ae. vexans is a serious nuisance pest. Females will
feed in shady places during the day; however, they are very active [at] dusk and vigorously seek blood meals at this time…

“House Mosquito”

Culex quinquefasciatus mosquitoes are
common in urban and suburban communities as well as on rural premises.
They readily breed in storm sewer catch basins, clean and polluted
ground pools, ditches, animal waste lagoons, effluent from sewage
treatment plants and other sites that are slightly to very eutrophic
or polluted with organic wastes. Development from egg to adult
is temperature dependent; requiring 8 to 12 days in summer. After
blood-feeding, females may return to the same or nearby larval
habitats to oviposit and are often considered non-migratory mosquitoes.
However, females may travel considerable distances from resting
sites to search for blood hosts, and marked females have been
shown to travel up to one half mile in a single night.

EPA: Do Stormwater Retention Ponds Contribute to Mosquito Problems? [emphasis added]
…Reducing our reliance on stormwater ponds for runoff control is
another way to reduce potential mosquito breeding habitat.
More people
are turning to alternative non-structural techniques, such as rain
gardens, bioinfiltration, infiltration, and vegetative swales, that
slow down water and help it infiltrate without extended periods of
ponding. These techniques are successfully minimizing or eliminating
the need for stormwater ponds or significantly reducing the pond size
requirements. Care must be taken to ensure that these alternative
controls drain all standing water as designed over the years.

Similarly, efforts to reduce the amount of impervious surface
in communities can reduce the need for stormwater ponds.
streets, sidewalk-less communities, and elimination of cul-de-sacs are
just a few of the ways that communities are now reducing the need for
stormwater controls. That is not to imply that stormwater ponds can be
eliminated easily. Retention/detention ponds use less space than many
other types of stormwater controls and are often found to be the best
and cheapest way to control runoff–especially when flooding is a

Mosquito proliferation in stormwater ponds is a concern,
especially when so many wet and dry ponds are in place and continue to
be installed across the country. Many ponds are not properly
maintained, particularly in cases where they are installed in
subdivisions and other developments where the entity responsible for
long-term maintenance is not clearly defined once the construction is