About six months ago, the U.S. Centers for Disease Control issued a travel warning for people visiting islands in the Caribbean because chikungunya virus had been detected on the island of St. Martin. This was the first time it had been detected in the Americas.
Now, in addition to the islands, health authorities are preparing for the virus to infect people in the U.S. itself.
“It’s not a matter of if, but when,” Dr. James Crowe, an infectious disease expert at Vanderbilt University, recently said to USA Today.
According to the National Association of County and City Health Officials (NACCHO), “it is virtually certain” that the virus will become established in the U.S. According to Paul Etkind, senior director for infectious diseases at NACCHO, “Local health departments should expect to see more of these cases as travel to the Caribbean for business and pleasure purposes increases over time. In addition, hundreds of thousands of soccer fans, many from the United States, are expected to travel to Brazil in July for the World Cup. The opportunities for introduction of the virus via infected fans returning from the games will be many.”
From the Georgia Mosquito Control Association newsletter – DIDEEBYCHA
In 2001, the CDC and the Pan American Health Organization jointly released a document entitled Preparedness and Response for Chikungunya Virus Introduction in the Americas. In late 2013, Chikungunya was found for the first time on islands in the Caribbean, where it has persisted and continued to spread.
Chikungunya fever is an emerging, mosquito-borne disease caused by the Chikungunya virus. It is transmitted predominantly by Aedes aegypti and Aedes albopictus, the same species involved in the transmission of dengue. Chikungunya is an RNA virus that belongs to the Alphavirus genus in the family Togaviridae. The name chikungunya derives from a word in Makonde and roughly means “that which bends,” describing the stooped appearance of persons suffering with the characteristic painful arthralgia.
Epidemics of fever, rash, and arthritis resembling CHIK were reported as early as the 1770s. However, the virus was not isolated from human serum and mosquitoes until an epidemic in Tanzania in 1952−1953. Subsequent outbreaks occurred in Africa and Asia, many of them affecting small or rural communities.
In Asia in the 1960s, CHIKV strains were isolated during large urban outbreaks in Bangkok, Thailand. These large outbreaks also occurred in Calcutta and Vellore, India, during the 1960s and 1970s. After the initial identification of CHIKV, sporadic outbreaks continued to occur, but little activity was reported after the mid-1980s. In 2004, however, an outbreak originating on the coast of Kenya subsequently spread to Comoros, La Réunion, and several other Indian Ocean islands in the following two years.
From the spring of 2004 to the summer of 2006, an estimated 500,000 cases had occurred. Since 2004, Chikungunya virus had been causing large epidemics of chikungunya fever, with considerable morbidity and suffering. The epidemics had crossed international borders and seas, and the virus had been introduced into at least 19 countries by travelers returning from affected areas. Because the virus had been introduced into geographic locations where the appropriate vectors are endemic, it was thought likely that the disease would establish itself in new areas of Europe and the Americas.
What about Georgia? There certainly is a risk of introduction and spread; there is no immunity and appropriate vectors and hosts exist here. McTighe and Vaidyanathan (2012. Vector-Borne and Zoonotic Diseases, Vol. 12:867-871) tested the vector competency of Virginia and Georgia strains of Ae albopictus for CHIK virus and determined that they were all highly competent vectors of this virus. In their conclusions these last authors stated, “Only early and specific detection of human cases coordinated with vector control can reduce the risk of local transmission of CHIKV in the US.”
Human Disease Symptoms:
High fever (103-104 F)
Rash
Severe incapacitating arthritis/arthralgia.
o Generalized
o Usually acute (several days to several weeks, though 20% of individuals have long-term joint complaints)
Hemorrhagic manifestations have been reported (rare)
Rarely if ever fatal – may cause encephalitis
These symptoms appear on average 4 to 7 days (but can range from 1 to 12 days) after being bitten by an infected Aedes mosquito. Infected individuals develop a high titer viremia and can infect mosquitoes during this time period.
State public health officials in Georgia support an integrated approach for mosquito control. Local officials can contact the Department of Public Health for more information about how to conduct an integrated program in their counties.
Asian tiger mosquito, Ary Farajollahi, Bugwood.org
A number of published reports suggest that mosquito control programs, and especially those using Integrated Mosquito Management techniques, are needed to reduce the risk of arboviral (West Nile Virus and some other mosquito vectored diseases) transmission at the local level. A study from Michigan indicated that people in communities with no mosquito control program had a tenfold greater risk of West Nile fever/encephalitis than those in areas where mosquitoes were controlled http://www.cdc.gov/ncidod/dvbid/westnile/conf/pdf/Walker_6_04.pdf
A Chicago area study suggested that mosquito control programs made a difference in WNV infection rates. The Des Plaines Valley District, with an intensive program to kill mosquito larvae, had four West Nile fever/encephalitis cases per 100,000 people, while the North Shore District, with a less ambitious program, had 51 cases per 100,000. This study showed that the program with the most mosquito surveillance and best documented larviciding and adulticiding operations had the fewest number of West Nile fever/encephalitis cases (Tedesco, Ruizand and McLafferty 2010).
This is not new information. The efficacy of aerial insecticide applications to reduce the transmission of Saint Louis Encephalitis (SLE) virus was shown during an epidemic in Dallas, TX in 1966. This study presented evidence that infection rate is reduced as a consequence of anti-mosquito measures. Before aerial spraying there was an SLE virus infection rate of 1 in 167 mosquitoes tested. After aerial control operations the SLE virus infection rate was 1 in 28,639 mosquitoes (Hopkins et al. 1975)
So, are small programs important? There was a documented increase in vector populations after the temporary closure of Clayton County, Georgia’s mosquito control program. There was an apparent increase in the risk of West Nile fever/encephalitis based on the presence of increased numbers of vector species and the detection of an early human case of West Nile fever/encephalitis in 2010. There was also a suspected increase in nuisance species and mosquito complaints, although these data were not collected. The Clayton County program has since been re-instated and is administered by Public Works.
Since the size of mosquito populations is crucial to disease transmission, it is important to reduce these populations below transmission thresholds. Even small programs can provide a reduction in vector populations and reduce the risk of vector-borne disease transmission.
Hopkins, CC et al. 1975. The epidemiology of St Louis encephalitis in Dallas, Texas in 1966. Am J Epidemiol 102: 1-15.
Tedesco C, Ruiz M, and McLafferty S. 2010. Mosquito politics: Local vector control policies and the spread of West Nile Virus in the Chicago region. Health & Place, 16 (6): 1188-1195.
Historically, more soldiers have died from insects than from bombs or bullets. In addition to malaria and yellow fever, soldiers have faced dengue, typhus, leishmaniasis and other insect-borne diseases.
The United States has taken the threat from insects very seriously. Today the U.S. Army, Navy, and Airforce all have trained entomologists to improve the health and sanitary conditions of their personnel. So on this Memorial Day — we thank our military entomologists, and all others who have served in the U.S. armed forces.
County and city officials in the Southeast spend millions of dollars each year to combat mosquitoes. But those costs are only a fraction of what Southeastern families spend to keep their furry family members safe from mosquito-borne parasites.
Each year Georgians spend between $9 million and $14 million treating heartworms in their dogs, said Elmer Gray, an Extension entomologist with University of Georgia Cooperative Extension. Dog owners across the country spend about $1.2 billion on heartworm prevention, and Gray estimates that about $40 million of that amount is spent in Georgia.
Those price tags dwarf the $7 million cities and counties in Georgia spend to keep mosquito populations under control and make heartworms the largest mosquito-related expense in the state.
“It really is the most expensive cost associated with mosquitoes,” Gray said.
Heartworm-related expenses are sometimes left out of studies calculating the economic impact of mosquitoes, but Gray believes these costs should be included.
“If it wasn’t for mosquitoes, there would be no dog heartworm problems,” Gray said. ”So consequently, the cost associated with heartworms – in my mind – is directly attributed to mosquitoes, thereby adding to the cost of dealing with this insect.”
He estimated the cost of prevention and treatment of heartworms with data provided by the UGA College of Veterinary Sciences and from Merial, a company that makes heartworm preventatives and other pharmaceuticals for animals.
The cost of preventative heartworm medicine is about $15 a month, and the cost of treating a heartworm infection can vary from between $600 and $1,000.
There are at least six species of mosquitoes that can transmit the heartworm parasite in Georgia. The flying insects pick up young heartworms, called microfilariae, when they feed on the blood of an infected animal. The microfilariae spend about two weeks maturing into larvae inside the mosquito, according to the American Heartworm Society.
When the mosquito takes its next meal, the larvae are deposited into the new host animal where they will mature into adult heartworms over the next six months.
Without treatment, the worms congregate around the right side of the heart and the arteries of the lungs where they can eventually cause heart or liver failure.
Dogs, cats and even humans can all be infected by heartworms, but the infections are most serious and most prevalent among dogs.
Southeastern states have the greatest prevalence of heartworm infections, and there’s an almost 100 percent chance that a dog living in Georgia will have the disease by age 5 if its owners don’t give it monthly preventive treatment, Gray said.
While cities and counties will continue to battle mosquito populations in Georgia, there is no way to reduce populations enough to prevent dogs and other animals from being infected with heartworms without medication.
“It would be impossible to prevent heartworm infections by controlling mosquito populations,” Gray said. “However, treating dogs with the proper preventative medicine is 100 percent effective at preventing the disease.”
As we move into the last weeks of summer, be aware of the excellent conditions for mosquito development that this summer’s heavy rains have created. This year has been very different from recent years when we consider our local rainfall totals. To date, much of the state is 15 inches or more ahead of normal rainfall for this time of the year. As a result there is more standing water in our counties and communities than in recent memory. This standing water will provide excellent larval habitat for mosquitoes as we move into the last few weeks of summer.
Mosquitoes are semi-aquatic insects that require standing water for the larval and pupal stages. There are 63 species of mosquitoes
Mosquito life cycle, Art Cushman, USDA Systematics Entomology Laboratory, Bugwood.org
known in Georgia and as result they exhibit a range of life histories.
Typically, the female mosquito will lay eggs on the surface of the water, attached to the sides of a container just above the water’s surface or on moist soil that will become covered with water at a later date. After being covered with water and in due time, the eggs hatch and the larvae (or “wigglers” as they are commonly called) develop in the standing water. The larvae are filter feeders, feeding on small particles of plant and animal matter.
After developing through 4 instars the larvae progress to the pupal stage which is commonly called a “tumbler” due to their movement through the water. Both the larvae and pupae come to the water’s surface for air and move down into the water when disturbed. After 2-3 days in the pupal stage the adult mosquito that we are all familiar with will emerge onto the water’s surface.
In the late summer, this cycle can be completed in as little as 7 days. This summer, with the numerous cloudy days and relatively cool temperatures, this cycle has surely been extended. The cool night temperatures have probably been the only thing preventing even worse mosquito populations than we have already experienced.
Homeowners can often reduce mosquito populations around their homes and neighborhoods by being diligent. All standing water should be eliminated or treated with an EPA approved larvicide if mosquito larvae are present. Emptying buckets, plant saucers, boats, tarps and anything else that can hold water is extremely helpful. Keeping gutter’s clear of leaves and debris will help to eliminate the often neglected larval habitat of backed up gutters. Homeowners should also check those rain barrels that were so helpful in past year’s droughts. It is vital that screens are intact around all openings or these barrels will become highly productive mosquito habitats. In addition, screens on the windows and doors should be checked to make sure there are no holes. Many mosquitoes are attracted to light and will be drawn to open windows after dark when we’re trying to get some fresh air in our homes.
As of August 22, the Georgia Department of Public Health has only reported 2 human cases of West Nile virus (WNV) in Georgia. This low number of cases is in contrast to last year when Georgia experienced a record 117 cases of WNV with 6 deaths. The WNV is now known to occur across the state and has been isolated from mosquitoes in the four counties (Chatham, DeKalb, Glynn and Lowndes) where adult mosquito surveillance and testing are being conducted this year.
The low number of human WNV cases is likely related to the fact that the mosquito (the Southern House Mosquito) that transmits the disease often develops in the storm drain system, particularly during dry periods. With this year’s heavy and regular rainfall, the storm drain systems across the state are regularly flushed and populations of this mosquito have been somewhat suppressed. However, we don’t want people to let down their guard as football season arrives. The peak period for WNV transmission in Georgia has historically been August 15-September 15. The proper use of EPA approved repellents is highly recommended if people are expecting to encounter mosquito populations in the next few weeks.
Products containing DEET are recommended for use on children as young as two months by the American Academy of Pediatrics. Parents should apply the repellent to their hands and then apply it to the children. It is important to get good coverage and then wash the treated skin upon returning indoors.
In conclusion, mosquito control districts across the state are reporting high numbers of complaints due to a variety of species of mosquitoes that have benefited from the abundant rainfall. Health districts across south Georgia are also seeing an increase in Eastern Equine Encephalitis (EEE) in horses. This disease is caused by a virus that is transmitted by mosquitoes that typically develop in the swamps and woodlands below the fall line in Georgia. While cases are rare in humans, EEE symptoms range from mild flu-like illness to encephalitis (inflammation of the brain), coma and possibly death. Symptomatic cases have a fatality rate of 30-50% and it is classified as the most severe mosquito-borne disease of humans in the United States.
Preventing mosquito bites is crucial to avoiding any of the mosquito-borne diseases. Loose fitting, light colored clothing, coupled with the proper use of EPA labeled repellents, will go a long ways towards this goal by making us less attractive to mosquitoes.
For years, bedbugs have been turning up in sometimes odd and random places, such as subways, movie theaters, dressing rooms and schools, but scientists believed that to flourish, the insects would need more frequent access to human blood meals.
Turns out they don’t.
Bed bug Gary Alpert, Harvard University, Bugwood.org
A new University of Florida study, published online this month by the journal Medical and Veterinary Entomology, shows the blood-sucking insects can do much more than survive — they can even thrive — with far less access to human blood than previously believed.
The Agency for Toxic Substances and Disease Registry (ATSDR) and the Centers for Disease Control and Prevention (CDC) are alerting the public to an emerging national concern regarding misuse of pesticides to treat infestations of bed bugs and other insects indoors. Some pesticides are being applied indoors even though they are approved only for outdoor use. Even pesticides that are approved for indoor use can cause harm if over applied or not used as instructed on the product label.
There has been a dramatic increase in the number of bed bug-related inquiries received by the National Pesticide Information Center (NPIC) over the past several years, with many involving incidents of pesticide exposure, spills, or misapplications.
Having policies and protocols in place to prevent and eliminate bed bugs in educational facilities is key to protecting students and should be an integral part of your IPM (integrated pest management) program.
About six months ago, the U.S. Centers for Disease Control issued a travel warning for people visiting islands in the Caribbean because chikungunya virus had been detected on the island of St. Martin. This was the first time it had been detected in the Americas.
