West Nile Virus Is Picking Up Across California
Early surveillance suggests this may be a more active season than we’ve seen over the past couple of years. It can be found year round but tends to peak in late summer/early fall. So even though some cases are expected, health officials are finding substantially more infected mosquitoes and birds than at this point last summer. This often serves as an early warning before human cases begin to increase later in the season.
It seems like a good time to update our mosquito post.
Even if they weren’t carrying any diseases, we hate mosquitoes. Yes we are aware that they are part of nature’s vast food chain but that doesn’t stop our loathing. For the record, it is a mutual dislike and fortunately we both rarely get bitten. The rest of our families? They are tasty targets, and are feasted on when given the opportunity.
West Nile History
Of all the mosquito-borne illnesses, the West Nile virus is the one that has gotten the most local media coverage. It is California’s most common mosquito-borne illness. It is thought to have originated in Africa (hence the name.) It has spread throughout the world and it was first detected in this country in 1999. Unfortunately we now have it in most states.
Transmission
Mosquitoes get this virus from feeding on infected birds. They then transmit it to humans. Humans are referred to as ‘dead end hosts’; they get the virus from being bitten by the infected insect, but then can not spread it to each other.
It is possible that it can be transmitted from blood transfusions, pregnancy or breastfeeding but there are no known cases of infants who have gotten seriously ill from these transmissions.
Incubation Period
The incubation period is usually between 2-14 days after the bite from an infected mosquito (most commonly 2-6 days.) There is, alas, no treatment beyond supportive care. It is thought that most people who have fought off the illness end up with some level of immunity. Keep in mind that any severe headache-fever-stiff neck combination always needs to be evaluated right away. If West Nile virus is suspected there are blood tests that can help with the diagnosis.
Symptoms
Fortunately, most people (around 80%) who become infected never develop symptoms. In fact, There are probably thousands of cases that go under the radar since we would never consider testing.
The unfortunate other 20% of infected folks may have
Fever
fatigue
headache
joint pain,
muscle weakness,
stiff neck, diarrhea,
vomiting,
swollen glands,
photo-phobia
rash on the trunk.
Not everyone will have every symptom. Most people showing these mild to moderate symptoms will recover completely, although there are reports that some of these folks can remain fatigued and achy for several weeks. 1% of infected people can get more serious neurological complications including encephalitis and meningitis. These are almost always adults over 55 or folks with compromised immune systems; it can be fatal for those with serious cases. Children under 5 seem to be at relatively low risk for getting seriously ill.
Prevention
Because there is no vaccine or specific treatment, prevention is the best protection:
Empty standing water around your home every week (flowerpot saucers, buckets, kiddie pools, clogged gutters, bird baths).
Use an EPA-approved insect repellent when spending time outdoors, especially around dawn and dusk. (there is a list of these below)
Dress in long sleeves and pants if you’ll be outside when mosquitoes are most active. Light colored clothing is recommended. There are plenty of mosquito prevention clothing on the market.
Here is nurse Judy rocking her safari hat. (How nerdy does it get?!?)
Make sure that you have intact screens on all windows. If you are getting bites, check for holes or cracks where the insects might be getting in. If your little one is still getting bitten, check the bedroom carefully. Look at the mattress and all the corners of the room; bites could be from spiders, fleas or other culprits.
Get rid of any standing water that is around your house; do a double check to make sure there are no pots, clogged gutters, kiddie pools, bird baths...etc. that are places where mosquitoes can breed. The larvae are dependent on water for breeding.
Unfortunately just dumping out the water might not be good enough because it won’t dislodge the larvae that might be attached to the side. You really need to give a good scrub. Check out Mosquito bits and mosquito dunks. You can add these to any water features to keep the mosquitoes from breeding.
There is often increased mosquito activity during dusk and dawn so that is when most of the biting happens. This seems to be true for the mosquitoes who carry West Nile Virus, not as much for Zika.
If you are going into a heavy mosquito area use bug spray on exposed skin and clothing. Mosquito repellent works only on the surface to which it is applied directly. Experiments have shown that they will actually bite skin only four centimeters away from where the repellent is applied, so wristbands or just spraying clothing does not offer full protection.
Some bug experts would rather that you avoid the traditional electric bug zappers. The violet light may be irresistible to some flying insects, (and that zap is such a satisfying noise), but mosquitoes are actually not attracted to the light. Some of the innocent and beneficial insects are the ones getting fried.
If you have a garden, consider planting some of the plants that mosquitos tend to avoid. This includes lavendar, citronella and basil.
Mosquitoes don’t like fans! If you are looking for an alternative to the DEET, the insects are lightweight enough that a good breeze may make it hard for them to zoom in on their target. Check out products such as Off Clip on Fan.
If you are seeing mosquitoes around your house, see if your local health department will check the area around your home (including sewers) to see if they can find any breeding areas.
Report dead birds to California’s West Nile surveillance program: 1-877-968-2473 (1-877-WNV-BIRD), or at https://westnile.ca.gov/report
. They help public health officials monitor where the virus is circulating.
Alas, long sleeves alone aren’t going to do the trick if you are out in a buggy area.
The EPA has five registered insect repellents.
DEET is likely the most well known option. It is the only product labeled safe for infants as young as 2 months old. It comes in different concentrations. The concentration of DEET in a product indicates how long the product will be effective. A higher concentration does not mean that the product will work better; It means that it will be effective for a longer period of time. Therefore, products containing lower concentrations of DEET may need to be reapplied, depending on the length of time a person is outdoors. Despite common concerns, DEET has been studied extensively and has an excellent safety record when used as directed (it’s not great for the ecosystem, so use DEET wipes when possible rather than spraying). One practical note: DEET can damage some plastics and synthetic materials (such as certain eyeglass frames, watch faces, or phone cases), so apply it before handling these items and wash your hands afterward.
Oil of Lemon Eucalyptus is considered one of the least toxic options but interestingly, the age recommendation for it is for 3 years and older (natural lemon eucalyptus oil is not the same as Oil of Lemon Eucalyptus). Some people are sensitive to the smell of this, so it is worth sniffing it before you buy it. This is the main ingredient in Repel brand spray.
Picaridin is odorless and is approved for children 6 months (recently lowered from 2 years) and older. Unlike DEET, picaridin will not dissolve plastics, synthetic fabrics, sunglasses, or fishing lines. Common brand is Sawyer.
Avon Skin so Soft Bug Guard PLUS IR3535 Insect Repellent has been around for years but seems to be more commercially available than it used to be (also for over 6 months of age.) It comes in a highly rated product that combines Avon Skin So Soft and an SPF 30 sunscreen
Bite Blocker is a botanical formula that claims to provide protection for up to 8 hours. The reviews mention a strong odor, but otherwise it gets a high rating.
All of the EPA recommendations are considered safe, and they are clearly better than getting bitten, but at the same time, let’s use them wisely. The EPA has created the following tool to help you find the proper product for you needs
EPA guide to finding the right repellent
Note: If you are also using sunscreen, apply sunscreen first and insect repellent second.
Regardless of what you try, before applying anything topical to the skin for the first time, do a little test patch on the skin to make sure there is no sensitivity before you widely spritz or wipe on any of these products. You will need to read the labels to see how often you need to reapply. Avoid contact with eyes and keep all of these safely away from kids.
We would also be cautious about getting any insect repellents on little hands, especially if your child is young enough that those hands are going into the mouth a lot.
Some products are more effective than others for certain types of mosquitoes, so the product you choose might depend on where you are going and what you might be most at risk for. It is always good to check in at https://wwwnc.cdc.gov/travel prior to any travel.
There are also plenty of natural products on the market that claim to be repellents, ranging from Vitamin B to catnip. Most of these are generally safe, but unfortunately the scientific studies show that they are mostly ineffective.
DEALING WITH A BITE
If the prevention has failed, the most important thing is to treat the itching. Scratching at a bite will make it worse.
As soon as you notice a bite, giving a dose of cetirizine (Zyrtec) as quickly as you can manage, can help reduce the itching and may lessen the amount of swelling that develops. It works best when given early. 1% hydrocortisone applied early can be similarly helpful, and the combination of Zyrtec or Claritin plus topical hydrocortisone is often more effective than either alone for symptomatic relief.
Hydrocortisone cream probably works the best, but other topical treatments can include calamine lotion, or mixing up a paste of baking soda with a bit of water. A cold black tea bag compress can also be very soothing. Black tea contains tannins, which seem to help.
Be aware: some kids can have enormous reactions. Eyes and ears can be remarkably swollen. A super swollen eye along with symptoms of illness needs immediate medical attentions, but if you child seems fine other than the swollen eye, it is usually a bite. Topical treatment alone won’t be enough for these. Hopefully, the early dose of antihistamine will help. Scroll to the bottom for dosing info. It is worth being seen if the you don’t see improvement.
Zyrtec Dosage Chart
The dose of cetirizine depends on age:
· 6 - 12 months of age: 2.5 mg given once daily (maximum dose 5 mg daily)
· 12 - 24 months of age: 2.5 given once or twice daily (maximum dose 5 mg daily)
· 2 - 6 years of age: 2.5 - 5 mg given once daily (maximum dose 5 mg daily)
· Over 6 years of age: 5 - 10 mg given once daily (maximum dose 10 mg daily)
Zyrtec comes in a 1mg/ml solution (so 2.5 mg = 2.5 ml). There is also a 10mg/ml oral drops preparation (so 5 mg is 1/2 ml). Make sure you check the strength of the solution.
Benadryl tends to be an inferior treatment. It lasts ¼ the time of Zyrtec and has more side effects.
New on the market: There are some bite pens that use a combination of heat and vibration. If used properly, these are safe and potentially helpful
Here are some bonus facts about mosquitoes:
Both males and females make that awful whining noise, but only the females bite humans.
That whining sound comes from their wings beating an incredible 300 to 600 times per second.
Mosquitoes are especially attracted to people who drink beer.
Mosquitoes love the smell of sweaty feet.
Mosquitoes can sense CO2 from up to 75 feet away.
Mosquitoes only fly as fast as 1-1½ miles per hour.
Some blood types may be tastier than others. O seems to be the favorite, A the least. B lands somewhere in the middle.
Mosquitoes love pregnant women (regardless of their blood type) possibly because they emit a little extra CO2.
Mosquito activity can spike by up to 500% during a full moon because they rely on visual cues to navigate.
Mosquitoes are responsible for more human deaths than any other animal due to the diseases they transmit, such as malaria and dengue.
Mosquitoes have existed for over 100 million years and have adapted to survive in a wide range of habitats, from wetlands to urban areas.
For further reading, here is some current info on some of the more common mosquito borne illnesses
West Nile Virus
https://www.cdc.gov/west-nile-
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