[begin Rod Sterling narrative]
It was a typical summer morning for new high school graduate Mary Doe. She donned a robe from her closet and went down the hall to fix breakfast. Little did she suspect what would follow her out of that closet.
It followed her into the kitchen, with only one thing in mind. Her blood. Mary Doe was about to be the subject of a vicious attack. It wanted blood, her blood, to make its babies.
The babies would spread, throughout the house, the neighborhood and the city. Mary Doe’s blood would not be the first to be taken by these monsters.
[end Rod Sterling narrative]
If mosquito bites were a movie, that is how the movie would begin. Nearly everyone has experienced a mosquito bite, the raised bump, the unbearable itching. The story of mosquitoes and man is a complex tale of adaptation, co-existence and far too often, a deadly illness.
The United States, and upstate New York, are very familiar with both mosquitoes and the illnesses they may carry. The ease with which the world interconnects at this time is bringing some strangers to America, new breeds of mosquito and new illnesses.
Not all mosquitoes bite humans. Some bite both animals and humans. Some only bite humans. All biting mosquitoes have one thing in common, they’re female. The blood they draw when they bite allows them to reproduce. The illnesses, viral, bacterial and parasitic, that they ingest from sick people and carry to other people, are just incidentals to their main purpose. They want to make babies and they need our blood to do it.
WEST NILE VIRUS
Rochester and Upstate New York residents are familiar with the West Nile virus. It arrived in the United States about 1999, and was first discovered in New York City. While most people infected with the virus show no symptoms, those with symptoms suffer a flu-like illness for days or weeks. In less than one percent of those infected, life threatening forms of West Nile called West Nile encephalitis, West Nile meningitis or West Nile meningoencephalitis can develop.
This map reflects surveillance findings occurring between January 1, 2009 through December 31, 2009 as reported to CDC's ArboNET system for public distribution by state and local health departments.
West Nile is spread by various members of the Culex family of mosquitoes with Cx. Pipiens being the primary carrier in New York. It is also called the Northern House Mosquito.
Cx. Pipiens loves the filthy water around people. It breeds in storm drains and sewers, even raw sewage and at sewage treatment plants.
It feeds on birds, some mammals and on humans.
New York has not seen a local outbreak of yellow fever since about 1870. Before then, the illness was a regular visitor to New York City, Albany and other parts of the state.
The following partial list of outbreaks in New York State is from the World Health Organization publication Yellow Fever, published in 1998.
1694 in Boston, New York and Philadelphia
1702 in New York
1734 in New York, Boston, Charleston, Philadelphia and Albany,
1743 in New York and Virginia
1745 in New York and Charleston
1751 in New York and Philadelphia
1791 in New York and Philadelphia
New York in 1801, 1819, 1821, 1822, 1870
1870 New York The last recorded outbreak of yellow fever in New York
Aedes aegypti is the usual mosquito carrier of this illness. Currently it is found much farther south than New York, though its range varies with the weather.
Aedes aegypti has re-emerged in the Americas following a successful hemispheric eradication campaign during the 1950s and 1960s. CDC map
A. aegypti is very adapted to living around humans. It has regulated its wing speed to reduce the buzz or hum that humans identify with mosquitoes. It is a day feeder, choosing the early morning or late evening to feed. During the heat of the day these mosquitoes seek out dark hiding places where there is little air circulation, like closets or under tables. Most bites from A. aegypti are to the lower leg.
A. aegypti is the opposite of the Culex mosquitoes when it comes to breeding sites. It seeks clean water, rain gutters, clear pools and containers that have collected rain.
Malaria may be one of the earliest illnesses to be described. It is a deadly illness, killing about a million people worldwide every year. It was considered eliminated in the United States by 1951.
In New York, the malaria risk was along the waterways, New York City, up the Hudson River to Albany, along the Mohawk River west, the Lake Ontario and Lake Erie shorelines.
Distribution of Malaria in the United States and Canada in 1882 Reiter, Paul: Environmental Health Perspectives: Vol. 109 -suppl. 1-: Figure 4, Pg 149, March 2001.
Malaria is a parasite carried and transmitted to humans by mosquitoes in the genus Anopheles. An. quadrimaculatus is the variety common to the New York area.
Despite the eradication of malaria in the United States, cases are discovered every year. Most are acquired by travelers in regions of the world where malaria is prevalent. There are occasional outbreaks, such as this one in New Jersey in 1991, that appear to be native. It is almost certain, however, that the initial host was a traveler who did not know they were sick and was bitten by mosquitoes. This is a common source of outbreaks of mosquito borne illnesses not native to the United States.
An. quadrimaculatus inhabits the eastern United States, east of the Mississippi. They prefer freshwater pods, steams and lakes with vegetation. The mosquito prefers to take blood from animals. They are night feeders.
Dengue fever has hit the headlines after an outbreak or series of outbreaks of this tropical illness in Key West, Florida. The last outbreak of this illness native to the United States was in 1945, so its reemergence in 2009 was startling.
There have been dengue fever cases and outbreaks traced to travelers, including cases in Florida at this time. One traces to Puerto Rico, another to Haiti, both areas where dengue is endemic.
Dengue is carries by A. aegypti. This should mean that the outbreak can only move as far north as this mosquito can survive, perhaps into the Carolinas. However, a recent illegal immigrant to the United States may change that assumption.
Ae. albopictus, the Asian Tiger mosquito, was accidentally brought in to the United States in the 1980′s. This map shows its range in 2000, and it most certainly has spread in the decade since the map was created.
USDA map of the distribution of the Asian Tiger mosquito in the United States in 2000
Ae. albopictus is known to spread dengue fever, as well as eastern equine encephalomyelitis and the Cache Valley virus. It is also reported to be able to carry West Nile.
The Aedes genera of mosquitoes are highly adapted to living near humans. they have also demonstrated a high degree of adaptation to changing habitat. Their eggs may survive for several months in a dried out area and revive when water returns to the area.
In an interview this week, Dr. Roxanne Connelly, who is Associate Professor and Extension State Specialist of Medical Entomology at the University of Florida, talked about mosquitoes with me. Mosquitoes vary by genera and species and can vary within the species with regional differences. That may include the ability to act as a good carrier of disease microbes. The existence of a particular type of mosquito in a region does not necessarily mean that an outbreak of illness is possible.
Dr. Connelly told me that the primary mosquito borne illness to be aware of in Western New York would be West Nile. She did suggest that a local outbreak of any tropical illness can occur if a sick traveler is bitten enough to create a pool of infection in the local mosquito population.
In an e-mail, Dr. Laura Harrington, Associate Professor, Department of Entomology at Cornell University, talked about the Asian Tiger mosquito, Ae. albopictus. She has found these mosquitoes in New York and New York City but they are not yet able to survive year round. This summer, she is working with others to identify the adaptations made by those Ae. albopictus that are now year round in New Jersey. She believes that any migration into New York by this mosquito would most likely come from the variety now living in New Jersey.
Dr. Harrington closed her e-mail with the suggestion that Rift Valley Fever could have a great impact on both humans and animals in New York should it be introduced. She states that we now have more than one mosquito capable of transmitting that illness.