Friday, September 4, 2020

Mosquito bites/West Nile Virus

West Nile Virus/ Mosquito Information

West Nile Virus has been detected in the Bay Area. It is 2020; this should not be a surprise to anyone. What else is coming our way? Oh yes, that asteroid right around election day...

Even if they weren’t carrying any diseases, I hate mosquitoes. Yes I am aware that they are part of nature's vast food chain but that doesn't stop my loathing. For the record, it is a mutual dislike and fortunately I rarely get bitten. The rest of my family, both of my daughters in particular, are tasty targets, and are feasted on when given the opportunity.

Of all the mosquito-borne illnesses, the West Nile virus is the one that has gotten the most local media coverage lately. 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, including California.

Mosquitoes get this virus from feeding on infected birds and 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.

The good news is that most of the time it is actually not such a big deal. Children under 5 seem to be at relatively low risk for getting terribly ill, and folks over 50 seem to get hit the hardest. It can be found year round but seems to peak in late summer/early fall. 80% of folks who get WNV have no idea that they are infected and feel perfectly fine. There are probably thousands of cases that go under the radar since we would never consider testing if someone is only showing mild symptoms of a mystery illness. The unfortunate other 20% of infected folks may have

  • fever,
  • 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. It can be fatal for those with serious cases. People with troubled immune systems are at the greatest risk.

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.

Since there is no vaccination at this point, and no treatment, the key is prevention.

Of course right now with Covid circulating, any fever is something that we pay attention to, but if there have been recent mosquito bites, make sure you report those as part of the relevant history.

Prevention is the key when it comes to dealing with mosquitoes.   

  •  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.

  • Get rid of any standing water that is around your house; do a double check to make sure there are no pots, 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 dunksYou can add these to any water features to keep the mosquitoes from breeding.

  • There tends to be 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.

  • Try to wear (keep your child covered with) long pants/ long sleeves etc. Light colored clothing is recommended.

  • 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.

  • Mosquitoes don’t like fans! The nasty insects are lightweight enough that a good breeze may make it hard for them to zoom in on their target. The Off! Clip on  has some folks who swear by it. If you are looking for an alternative to the DEET, it might be worth giving it a try (perhaps it is the fan aspect that makes it work…)

  • If you are seeing mosquitoes around your house, San Francisco's Environmental Health Department will send an inspector to investigate (415-252-3805.) They will check the area around your home (including sewers) to see if they can find any breeding areas.

Alas, long sleeves alone aren’t going to do the trick if you are out in a buggy area. There are 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. We have the luxury in the Bay Area of not having some of the more notorious mosquitoes, so the bites are mostly an aggravation rather than a health risk. If you are in San Francisco, it is not a big deal to give something a try to see how it works on your family members. However, If you are traveling to an area where there are more dangerous mosquitoes, I would stick with the strong stuff. No kidding around. 
 
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.

  • 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, it is worth sniffing it before you buy it.
 
 

  • 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.
 
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.

 I would also be cautious about getting any insect repellents on the hands, especially if your child is young enough that those hands are going into the mouth a lot. If you are also using sunscreen, apply sunscreen first and insect repellent second.

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
 
 
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. Trusting that someday we will be able to move around the globe again, it is always good to check in at https://wwwnc.cdc.gov/travel prior to any travel.

 
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.
There is a product called a mosquito zapper that some folks find useful. Young kids might be startled from the noise, but others claim that it is great for minimizing the reaction if you use it quickly.
 
Over the counter 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.

Some kids can have enormous reactions. Eyes and ears can be remarkably swollen. Topical treatment won’t be enough for these. Give a dose of Zyrtec or Benadryl right away. Scroll to the bottom for dosing info.  If the antihistamine doesn’t make a difference or if there is fever or severe discomfort, those kids need to be evaluated by a doctor.

 If your little one is 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.
 
 
 
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 dosage will be the same volume as your Tylenol dose. The liquid says for children 4 and over; we still use it for our younger patients who need it. Benadryl makes most kids sleepy but can have the opposite effect.

 If you are interested, Here is some current info on some of the mosquito borne illnesses that have been in the headlines the most in the past year or so.

West Nile Virus

If you see any dead birds, give them a wide berth and report them to 1-877-968-2473 (WNV -BIRD) or online at http://westnile.ca.gov/ That website also will give you the up to date numbers on how many West Nile virus cases there are in California, county by county. It is updated weekly. 


 

Here are some bonus facts about mosquitoes:
 
  • Both males and females make that awful whining noise, but only the females bite humans.
  • 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.



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