West Nile Virus in North American Bird Populations

The Spread of West Nile virus

Prior to 1999, you had probably never heard of West Nile virus, and in fact, until then it was virtually unknown in the US. However, that year 62 human cases, 25 horse cases, and countless bird diagnoses were reported in New York state. Since that time the virus quickly spread throughout the country and has been documented in all of the lower 48 states, affecting more than 40,000 people.

While the effects of West Nile virus on human populations have been studied in great detail, and we have a fairly good understanding of its impact on human health, we are only recently starting to understand how it can make changes to bird populations and the larger ecosystem.

Like many mosquito-borne pathogens, West Nile virus has a complicated life cycle requiring amplification in birds and mosquitoes before being transmitted to people. For a person to become infected, they must be bitten by a mosquito that has previously fed upon an infected bird. It is also important to note that not all mosquito species are capable of carrying the virus, although documented in greater than 150 species.

The majority (80%) of people infected with West Nile virus will experience no symptoms, but it is possible for this disease to be debilitating and even deadly. Approximately 20% of people affected by the virus will experience flu-like symptoms including fever, headache, nausea, muscle pain, and swollen lymph glands. An even smaller proportion of people (1 in 150) will develop West Nile Encephalitis or Meningitis, which can be life-changing and lead to disorientation, coma, tremors, convulsions paralysis, and even death.

While the majority of funding for West Nile mosquito surveillance and control targets protecting human health, it is important to note that humans are not the only animals infected. A recent study by researchers at Colorado State University indicates that bird populations are, and continue to be, hit heavily by the disease, and the consequences of this can have a significant impact on the ecosystem at large.

When a new disease enters an area, disease ecologists expect to see major die-offs in the first year. However, over time, the impact of the disease is expected to decrease as the host population experiences increased immunity and can recover. Using data collected from over a quarter of a million birds belonging to 49 species, researchers have found that about half of the avian species affected by West Nile virus have made a recovery; however, the other half are continuing to experience major decreases in their population. Given the additional pressures on bird populations throughout the United States, of climate change, altered land use patterns, and feral cats, the added impact of West Nile on these populations is concerning.

Why so many bird species are unable to recover from the effects of West Nile virus is currently unknown. But when we think about the effects of mosquito-borne diseases decreasing the population of any species by 8-10% per year, it is quite shocking and should give us all reason for concern. As biologists attempting to control these vector-borne diseases, it is important that we consider not only the effects of the disease on human populations but other animal populations and the greater ecosystem as well.

Contact Us to Learn More About Effective Mosquito Management Strategies:

VDCI_Logo_squareSince 1992, Vector Disease Control International (VDCI) has taken pride in providing municipalities, mosquito abatement districts, industrial sites, planned communities, homeowners associations, and golf courses with the tools they need to run effective mosquito control programs. We are determined to protect the public health of the communities in which we operate. Our mosquito control professionals have over 100 years of combined experience in the field of public health, specifically vector disease control. We strive to provide the most effective and scientifically sound mosquito surveillance and control programs possible based on an Integrated Mosquito Management approach recommended by the American Mosquito Control Association (AMCA) and Centers for Disease Control and Prevention (CDC). VDCI is the only company in the country that can manage all aspects of an integrated mosquito management program, from surveillance to disease testing to aerial application in emergency situations.

VDCI’s Jim Stark Addresses Zika Virus Concerns on “Let’s Talk, Jonesboro!”

Zika virus has been a highlight in the media over the last few months. With the public concerned, many communities are paying greater attention to how they protect their residents from mosquito-borne diseases this summer.

Zika_2.0.jpgThe city of Jonesboro, Arkansas is already preparing for the 2016 mosquito season. The city’s sponsored public affairs program “Let’s Talk, Jonesboro!” featured Jim Stark, a member of the Vector Disease Control International (VDCI) team, to provide details.

VDCI has maintained an Integrated Mosquito Management (IMM) partnership with the city for over 20 years. An integral part of the successful IMM relationship is VDCI’s Contract Supervisor, Jim Stark. The VDCI and Jonesboro relationship took a one-year hiatus. With the community feeling the “bite” that season they quickly returned to the experts at VDCI.

LetsTalkJonesboroAR.jpgJim spoke with host Roy Ockert Jr. about Zika virus, the importance of knowing the different species of mosquitoes in your community, where they breed, and most importantly, educating the public on how they can contribute to a reduced population.

VDCI is committed to public education and spreading awareness throughout the U.S. about the dangers of mosquito-borne diseases and their preventability, with the overarching goal of reducing the illness and fatality statistics in 2016. Our dedicated and experienced staff works tirelessly to prevent the spread of mosquito-borne diseases in all of the contracts we service. If you would like more information about any aspect of mosquito surveillance, disease testing, or adult control, please contact Vector Disease Control International (VDCI) and we will help you get started immediately.

Contact Us to Learn More About Effective Mosquito Management Strategies:

VDCI_Logo_squareSince 1992, Vector Disease Control International (VDCI) has taken pride in providing municipalities, mosquito abatement districts, industrial sites, planned communities, homeowners associations, and golf courses with the tools they need to run effective mosquito control programs. We are determined to protect the public health of the communities in which we operate. Our mosquito control professionals have over 100 years of combined experience in the field of public health, specifically vector disease control. We strive to provide the most effective and scientifically sound mosquito surveillance and control programs possible based on an Integrated Mosquito Management approach recommended by the American Mosquito Control Association (AMCA) and Centers for Disease Control and Prevention (CDC). VDCI is the only company in the country that can manage all aspects of an integrated mosquito management program, from surveillance to disease testing to aerial application in emergency situations.

What You Should Know About Zika Virus

mosquito-born diseases webinar

How It Spreads, Symptoms & Protection Strategies

What is Zika virus?
Zika virus (ZIKV) was first discovered in 1947 in the Zika Forest of Uganda. Shortly thereafter, it was isolated from mosquitoes in the area and then humans in 1968. ZIKV is a flavivirus similar to yellow fever, dengue, Japanese encephalitis, and West Nile virus (WNV). The disease had only been detected in central Africa and throughout Southeast Asia until associated with a diesease outbreak on Yap Island, in the South Pacific in 2007. From there, it spread to South America with human cases first reported in 2014.

Zika_PDF_ButtonHow does the virus spread?
ZIKV does not appear to require an animal reservoir, like WNV, which is perhaps a factor in the rapid spread throughout the Americas. Non-infected mosquitoes are able to acquire the virus after feeding directly on infected humans. Without a “middle man” in the endemic cycle of ZIKV, the virus can spread quite rapidly where abundant, competent vector mosquitoes and humans are present together. Today, there is active transmission of the virus throughout South and Central America and the Caribbean Islands. Please refer to Figure 1 in VDCI’s Zika Virus Fact Sheet.

Symptoms of Zika infection:
Typically, people with ZIKV infection begin showing symptoms with a mild headache. Within a day or two, a maculopapular rash may appear and can cover many parts of the body (arms, hands, face, and chest). Following the rash, people generally report continued fever, malaise, and body aches. Other symptoms can include diarrhea, constipation, abdominal pain, and dizziness.

Treatment of Zika Infection:
Treatment includes rest and the use of acetaminophen to relieve fever. Patients should also be advised to drink plenty of fluids if diagnosed. If anyone has recently traveled to a known endemic area, and are displaying any of the symptoms described above, they should consult their physician immediately.

Concerns with Pregnancy and Perinatal Infections:
If a pregnant woman is infected with the Zika virus, it may result in microcephaly, a birth defect causing underdevelopment of the head and brain in newborn children. However, the link between ZIKV and infant microcephaly is poorly understood at this time.

Preventing Zika Infection:
As always, we urge residents to reduce mosquito-breeding on the property by discarding or draining sources of standing water. Additional preventive measures, especially by pregnant women, are recommended during the daytime when Ae. aegypti are most active. Individuals that are traveling, or planning to travel, to countries where ZIKV or other mosquito-borne viruses are found, are urged to visit www.cdc.gov/zika/prevention.com and take the precautions as listed by the CDC.

Mosquito Vectors of Zika virus:
ZIKV is transmitted by Aedes mosquitoes. In the Americas, it has only been linked to transmission by Aedes aegypti. Ae. aegypti is also responsible for the transmission of dengue virus, yellow fever virus, and chikungunya virus. Recently in Senegal and again in Gabon, the virus was detected in Aedes albopictus, or the Asian tiger mosquito; hence, it is likely that Ae. albopictus could vector the virus in the Americas.More about Aedes aegypti:

Aedes aegypti mosquitoAe. aegypti, the yellow fever mosquito, is a medium-sized mosquito easily distinguished from Ae. albopictus by a silvery-white “lyre-shaped” pattern of scales on its scutum. Both species are peridomestic species found not far from human dwellings, and are particularly abundant in towns and cities. They are primarily early morning or late afternoon feeders, but females can also take a blood meal at night under artificial illumination. Aedes aegypti is reported to fly only a few hundred yards from breeding sites. Larvae can be found in a variety of artificial containers, including buckets, tires, cans, and flower pots.

Zika and Aedes aegypti in the United States:
As of February 2016, most US ZIKV cases were imported from travelers who contracted the virus in other countries and returned to the US while infected.

Both Ae. aegypti and Ae. albopictus are limited in their distribution in the US. Therefore, it is unlikely that ZIKV will become a disease that circulates in the local mosquito populations throughout the US like WNV, but select areas of the US are at higher risk because of climate. Please open VDCI’s Zika fact sheet, to view a map depicting each mosquito’s US distribution.

How VDCI Can Help Control Mosquitoes At All Stages of Life

VDCI recommends a 4-pronged approach for an effective mosquito strategy designed to target all phases of the mosquito’s life cycle:

(1) Public Education –  Focusing on the removal of mosquito breeding sources.

Given that these mosquito vectors live in and around urban settings, laying eggs in water-holding containers, community understanding of the sources of these mosquitoes and how to properly “mosquito-proof” their homes is critical. Furthermore, educational pieces that encourage individuals and families to seek prompt medical care when Zika virus is detected in a community should be distributed. Outreach to neighbors, work colleagues, and members of social clubs can reinforce messages disseminated through the mass media.

VDCI has developed numerous brochures, door hangars and fact sheets for various mosquito-borne diseases. In conjunction with door-to-door larvicide efforts, these materials can be delivered to homes and residents throughout affected neighborhoods.

(2) Surveillance – Seeking to understand a vector’s presence.

It is important to determine the mosquito distribution, density, and species composition throughout the target area. Furthermore, it will provide direct evidence of an increased transmission risk of Zika virus.

VDCI uses multiple traps to capture weekly samples of mosquitoes in various stages of their lifecycle. This complete surveillance approach is crucial for the efficient and precise control efforts in residential areas.

(3) Larval Mosquito Control – Focusing on the application of environmentally safe larvicides for the control of immature mosquitoes.

When mosquito larvae are detected in an area, trained and experienced ground crews preferentially apply treatments to all areas of standing water, stagnant pools, and water-holding containers. Only insecticides approved by the Environmental Protection Agency (EPA) for the control of mosquitoes should be used for all control applications.

Our crews work in two person teams to canvass a neighborhood. Appropriate habitats are inspected and, when appropriate, treated via backpack and hand-delivered applications of larvicide.

(4) Adult Mosquito Control –Targeted application of products for the effective reduction of pestiferous and disease-causing mosquitoes.

Truck-spraying-treatment

Truck-mounted and aerial ULV applications are often used to control adult mosquitoes. These methods have limited efficacy against the primary targets of Zika virus, due to the flight behavior of the Ae. aegypti and Ae. albopictus.

VDCI recommends the deployment of two person teams to conduct targeted ULV applications combined with residual “barrier” applications via backpack applicators to mosquito harborage areas near homes and other structures. When combined with our larvicide efforts, these applications have proven highly effective at significantly reducing local populations of Ae. albopictus.

VDCI is committed to public education and spreading awareness throughout the U.S. about the dangers of mosquito-borne diseases and their preventability, with the overarching goal of reducing the illness and fatality statistics in 2016. Our dedicated and experienced staff works tirelessly to prevent the spread of mosquito-borne diseases in all of the contracts we service. If you would like more information about any aspect of mosquito surveillance, disease testing, or adult control, please contact Vector Disease Control International (VDCI) and we will help you get started immediately.

Contact Us to Learn More About Effective Mosquito Management Strategies:

VDCI_Logo_squareSince 1992, Vector Disease Control International (VDCI) has taken pride in providing municipalities, mosquito abatement districts, industrial sites, planned communities, homeowners associations, and golf courses with the tools they need to run effective mosquito control programs. We are determined to protect the public health of the communities in which we operate. Our mosquito control professionals have over 100 years of combined experience in the field of public health, specifically vector disease control. We strive to provide the most effective and scientifically sound mosquito surveillance and control programs possible based on an Integrated Mosquito Management approach recommended by the American Mosquito Control Association (AMCA) and Centers for Disease Control and Prevention (CDC). VDCI is the only company in the country that can manage all aspects of an integrated mosquito management program, from surveillance to disease testing to aerial application in emergency situations.

Zika Virus: An Emerging Mosquito-Borne Infection in the Americas

Clsoe-up-mosquito

Discussing Zika and Aedes genus Mosquitoes

Over the past couple weeks Zika virus has taken the media by storm and US Health officials from the Centers for Disease Control and Prevention (CDC) have issued an advisory for pregnant women traveling to areas where the virus is known to be active. While this is not a new disease, it is the first time we’ve seen it in the Western Hemisphere and it is a major cause for concern as we understand more about the potential link between Zika virus and birth defects such as microcephaly.

The Zika virus was first isolated from a rhesus macaque in Uganda in 1947 and documented in humans as early as 1968. The reason we haven’t heard much about Zika until now is that the vast majority of human cases present with little to no symptoms. In fact, the CDC reports that only 1 in 5 individuals who contract the virus will become ill, and those that do will experience mild flu-like symptoms including fever, rash, joint pain, headache and conjunctivitis (red eyes).

While the Zika virus is strongly suspected to cause a severe birth defect called microcephaly, underdevelopment of the head and brain, it is important to note that the virus belongs to a family of viruses (Flaviviridae) not previously linked with birth defects and these side effects have not been noted in countries with previous Zika outbreaks. Since Brazil’s first case of Zika was documented in May of 2015, the incidence of microcephaly cases has increased dramatically with over 4,000 cases being documented in recent months. At this point in time, the link between Zika and infant microcephaly is poorly understood and there is not a quick and easy test for the virus, therefore making research efforts difficult. As with many viruses, there is no treatment for Zika and because it was not previously believed to be a major health concern, there is also no vaccine.

Aedes_aegypti_Adult_MosquitoesZika is spread to humans by the Aedes genus of mosquito.  The most common vectors for transmitting Zika include Aedes aegypti (Yellow Fever mosquito) and Aedes albopictus (the Asian tiger mosquito), which are also responsible for spreading the dengue virus, yellow fever, and Chikungunya.  Despite the fact these mosquitoes are restricted to tropical and subtropical regions, they are found in all but two North, Central and South American countries and found throughout much of the southeastern United States.   Aedes mosquitoes carrying the Zika virus lay their eggs in standing water and often utilize artificial containers found in and around human dwellings.  As day biting mosquitoes, these individuals are most active during daylight hours and often found resting indoors as they seek cool shaded areas.  While the males of all mosquito species do not bite humans or animals, females need a blood meal to mature their eggs and the close proximity of these species to human habitats makes them an important vector for disease transmission.

As with any mosquito-borne disease, it is important to keep in mind that not every mosquito carries the virus and an integrated approach to prevention is typically the most effective. Control of these vector species often starts with mosquito surveillance and relies heavily upon the removal and modification of breeding sites through source reduction and minimized contact between mosquitoes and people.

Dumping a birdbath, removing a tire, unclogging a gutter or draining a potted plant that holds water are all examples of source reduction. You can do your part by making sure that you have no standing water on your property, wearing long sleeve pants and shirts when outdoors and utilizing repellents with DEET or oil of Lemon Eucalyptus.

Contact Us to Learn More About Effective Mosquito Management Strategies:

VDCI_Logo_squareSince 1992, Vector Disease Control International (VDCI) has taken pride in providing municipalities, mosquito abatement districts, industrial sites, planned communities, homeowners associations, and golf courses with the tools they need to run effective mosquito control programs. We are determined to protect the public health of the communities in which we operate. Our mosquito control professionals have over 100 years of combined experience in the field of public health, specifically vector disease control. We strive to provide the most effective and scientifically sound mosquito surveillance and control programs possible based on an Integrated Mosquito Management approach recommended by the American Mosquito Control Association (AMCA) and Centers for Disease Control and Prevention (CDC). VDCI is the only company in the country that can manage all aspects of an integrated mosquito management program, from surveillance to disease testing to aerial application in emergency situations.

2015 Mosquito-Borne Disease Year in Review: From Encephalitis To The West Nile Virus

Mosquito-Borne Diseases In the U.S. in 2015

 In 2015, we saw a continuation of serious mosquito-borne disease cases in the United States. This blog covers three of many diseases that were transmitted by mosquitoes in 2015: West Nile Virus (WNV), Eastern equine encephalitis (EEE), and chikungunya. These three represent the most common mosquito-borne diseases we find in the United States, with WNV being far and away from the most common threat in U.S. territories. All of the information in this year’s review post was taken from the Center for Disease Control (CDC)’s data points and website as of 12/31/2015.

West Nile Virus (WNV):

WNV is the most common virus transmitted by mosquitoes to humans in the United States. While most infected people will have no symptoms, roughly one in five will develop symptoms that may include a combination of fever, headache, body aches, skin rash, or swollen lymph nodes. Other symptoms may include a stiff neck, sleepiness, disorientation, or even paralysis.

In 2015, 48 out of 50 states reported WNV infections in people, mosquitoes, or birds. In those states, 2,060 cases of WNV were reported in humans, and there were 119 confirmed deaths (5.8%) in 2015. This is in line with 2014 data, which had 2,205 human cases of WNV and 97 deaths (4.4%). Keep an eye out for a future blog post with much greater detail about WNV and its effect on humans, as well as on bird populations.

Eastern equine encephalitis (EEE):

EEE is also transmitted to humans by the bite of an infected mosquito, but is, fortunately, a rare illness for humans, with only a few cases reported in the United States each year. Although some people infected with EEE have no apparent illness, severe cases of EEE lead to inflammation of the brain, often beginning with a high fever, headaches, and vomiting. The illness will often progress into disorientation, seizures, or coma. EEE is a severe mosquito-transmitted disease, with about a 33% mortality rate. Additionally, even survivors can develop significant brain damage.

As of Nov. 17, the CDC reported five cases of EEE nationally in 2015: one in Louisiana, one in Maine, and three in New York. The Maine case and two of the New York cases were fatal. An average of eight EEE cases is reported each year in the United States, with 15 cases in 2012 and 8 cases in 2013 (2014 statistics presently unavailable). Keep an eye out for a future blog post with much greater detail about EEE and the many ways in which Vector Disease Control International (VDCI) helps prevent the spread of this deadly disease.

Chikungunya:

Traditionally, chikungunya outbreaks have occurred in countries in Africa, Asia, Europe, and the Indian and Pacific Oceans. Since 2013, chikungunya has been found in the Americas on islands in the Caribbean. Since then, about 1.5 million cases have been reported in the Americas. Symptoms are most often a high fever and joint pain. Other symptoms may include muscle pain, joint swelling, and headaches. Joint pain can often be debilitating, but thankfully, chikungunya is rarely fatal. Mosquitoes become infected when they bite someone already infected with the virus, and then infected mosquitoes spread the virus to other people they bite.

In 2015, 679 chikungunya virus disease cases were reported in 44 states. All reported cases occurred in travelers returning from affected areas, and importantly, no locally-transmitted cases have yet been reported from U.S. states in 2015. In 2014, a total of 2,811 chikungunya virus cases were reported from U.S. states, with twelve locally transmitted cases being reported from Florida. All other cases occurred in travelers returning from affected areas. Stay tuned for a future blog post with much greater detail about chikungunya and the ways VDCI helps prevent the spread of this potentially debilitating disease.

Zika:

Zika appears to be a growing threat for U.S. citizens traveling to South America and possibly Florida. Therefore, stay tuned for more information on that virus in the coming months.

Contact Us to Learn More About Effective Mosquito Management Strategies:

VDCI_Logo_squareSince 1992, Vector Disease Control International (VDCI) has taken pride in providing municipalities, mosquito abatement districts, industrial sites, planned communities, homeowners associations, and golf courses with the tools they need to run effective mosquito control programs. We are determined to protect the public health of the communities in which we operate. Our mosquito control professionals have over 100 years of combined experience in the field of public health, specifically vector disease control. We strive to provide the most effective and scientifically sound mosquito surveillance and control programs possible based on an Integrated Mosquito Management approach recommended by the American Mosquito Control Association (AMCA) and Centers for Disease Control and Prevention (CDC). VDCI is the only company in the country that can manage all aspects of an integrated mosquito management program, from surveillance to disease testing to aerial application in emergency situations.