Malaria, Zika, Dengue fever, Yellow fever, encephalitis,
Wow, it seems that Mosquitoes are worse carriers of disease
They are reported as being responsible for making 20% of the
world sick every single year.
In the USA, dengue fever and malaria are ‘back’. In Canada we
have West Nile Virus.
Like Canada and most of the USA, in Costa Rica, including the
Samara, Guanacaste region, mosquitoes are mostly ‘pests’ with
a low ‘risk’ of serious illness.
In Canada, we are told to take precautions because, while the
risk is low, it is not zero, most of this warning has come in
the past years as we’ve had more and more incidences of West
Nile Virus, and from my reading about the diseases from
mosquitoes in the USA, especially the Southern States, I
assume that people there should take precautions too.
But remember, you are going to be outside more – so your risk
will be higher because of that factor. And remember,
mosquitoes easily bite through thin clothing – especially
clothing that is tight against the skin like tight jeans, or
anywhere your clothing is ‘tight’ to hold it to your body –
such as a waist band if it isn’t very thick.
The most important piece of information in this page is the
‘So what should you do?’ part at the bottom.
So as of October 2019, using various sources, but especially
the Canada Blood Services and the CDC:
There is no “locally transmitted” Malaria in Costa Rica. One
source says “less than 10 in 100,000” and that is likely due
to people coming from Nicaragua or Panama or other countries
with the disease – not from catching it in Costa Rica. Note
that there is Malaria in nearby countries, such as the East
side of Nicaragua, one state in Panama ‘close’ to Costa Rica,
and several other states in Panama. While Guanacaste is
‘fairly’ close there is currently no worry in Samara, Nosara,
Liberia or really, any other areas of Costa Rica that you
might decide to travel to.
There is currently no “locally transmitted” Zika in Costa
Rica. But due a variety of reasons, the Canadian Blood society
requires that I not give blood for 21 days after I’ve been to
Costa Rica. As of writing, there are no Zika outbreaks, but if
there is, Costa Rica could become one of the locations.
Dengue: Fairly rare – one report said you are more likely to
get it in the Southern USA than in Costa Rica.
Yellow Fever: Not in this part of the world
Encephalitis: About the same risk as the USA.
Irritation. Is there anything of low volume more annoying than
a mosquito’s buzz?
Itch: Up until I was about 35 years old, mosquito bites itched
and itched and itched. I used gallons of ‘stop-itch’ through
the years, and those products only gave me short term relief.
But then when I was about 35, I was helping my wife at a kids
camp she was running, I counted over 100 mosquito bites (I
counted most of them.) on the second day. For years after
that, mosquito bites never itched – I guess I built up
immunity. But due to travelling and West Nile Virus, and
because I hate the sound and site of mosquitoes, I have used
more and more insect repellent since that time – and I noticed
in 2019 that mosquito bites, the few I did get, were starting
to itch a small amount. So I suspect if I keep not getting
many, my body is losing its immunity to the itch, and the few
I do get are going to be a good reminder to keep using
protection against bites.
So what should you do?
Use insect repellents that actually work. (Don’t fall for the
Amway skin lotion scam.) For most people, DEET and Picaridin
are your best choices. Whichever one(s) you use, apply them
See for details:
- A lot of people have concerns about DEET, but as far as I
can see, it all comes from mistaking DDT with DEET – two
completely different chemicals – completely. DEET seems
to, other than water, be one of the most tested and safe
chemicals in the world (And the chemical water can kill
you if you get too much of it – and you are much more
likely to get too much water – drowning – than have any
problem from DEET.) The only known ‘complications’ from
people with DEET from my research were people who had a
pre-condition that made them likely to get the second
problem – as a result the evidence is in the direction
that the DEET was not the causative agent. Anyway, I know
I won’t convince anyone who comes with the opposite
opinion, so I’ll stop now.
- Others have concerns about Picaridin since it is newer and
has not had nearly the testing or long term effect that
DEET has. But I personally, having read the research, use
DEET and/or Picaridin – I have no fears about either of
them. See our page on ‘Mosquitoes, Ticks, Flies’ for more
information on different options and how effective they
have proven to be in tests. Be more vigilant when you see
mosquitoes, cloudy days and dusk to dawn.
It is generally agreed that there is no need to sleep in mosquito netting in Costa Rica. If you want to, if you think about it as cool and exotic, fine go ahead, the risk is not considered enough to justify it, but if you are offered it, it won’t hurt. If you do use them, if you want them to make a difference, make sure you tuck them in otherwise they are nearly useless. Mosquitoes will follow the CO2 smell and get in. Note that on TV shows they usually have them hanging down over the sides of the bed – it looks better for TV – but when I’ve traveled in parts of India and other areas that need mosquito netting at night, they do it correctly, not ‘made for American TV.’
Clothing, there are various recommendations about clothing. These seem to me to be the most useful:
- Wear long sleeved, loosely fitting shirts and pants. Tight
fitting allow mosquitoes to bite through. If you use a
light material, or a moisture wicking lower level and
light, loose outer level, you have the bonus of it being
sun protection of SPF 15 or more. And lets be realistic,
you are more likely to get a bad sunburn in Costa Rica
than illness from mosquitoes.
- Tuck shirts in or use a loose belt/rope to prevent access
to your body that way.
- Use brightly colored (some say other than yellow)
clothing, not dark clothing. And after all, white clothing
keeps you cool in the sun.
- Cotton (including Jeans) and linen don’t prevent mosquitoes from
biting through, but many synthetic tight weave, including many
high tech sports clothing do.
Other comments and ideas:
- Stay indoors during from dusk to dawn when mosquitoes are
- Don’t spray DEET on clothing. Spray it into your hands,
then rub it on
- All exposed skin
- Ankles, elbows, neck, wrists, forehead (even if under
- Anywhere you have tight clothing. (This is not talking
about having a tight under layer with a loose outer
- Stay cool, have showers after you sweat. Besides it feels
good too! Mosquitoes are attracted to sweat. Don’t forget
to reapply repellent after swimming or showering or
- There are several things that increase your CO2 output:
Exercise (obviously), drinking alcohol, eating spicy
foods, being pregnant, being overweight. Bear this in mind
and use more repellent or, if you want, change your
habits. But again – not exercising is probably a bad
choice for the lesser risk of a mosquito bite in Costa
- If you want to try tiki torches and other citronella
candles and oils, set them on the ground. Mosquitoes live
very near the ground, and the smoke and scent only works
if it is between you and the mosquito. This is a ‘why not,
every little bit helps’ don’t rely on these as your
primary line of defense.
Mosquitoes are terrible at flying
- You may beg to differ when you are trying to swat them!
But a 1mph (2km) wind or higher is enough to keep
- Given a choice between a breezy location for your picnic
or book reading time and a calm sheltered location, choose
the breezy location. (Just be aware: Sunburn! You should
probably always apply sunscreen if you are going in the
sun, but In a breezy location you are more likely to
forget until you have had too much sun exposure.)
- As a side note, some sources say that the dusk to dawn has
nothing to do with the light. It has to do more with dusk
AND dawn – at those times of day the wind tends to be less
breezy, allowing the mosquitoes to fly
- If you are outside on a patio and it is calm, why not turn
one or two fans on – one for foot level (you don’t want
bites there) and one for head/body level.
For those living the life, a few more tips:
- Clear standing water daily, or just prevent it from
- Plant citronella, lavender, lemongrass, marigolds and/or
basil. While this won’t prevent mosquitoes, they will
repel some, and you get beauty and nice smell as well.
Think of this as ‘every little bit helps’ not as a major
- You may want to consider spraying. My research says,
unless it is done widespread (like at a municipal level)
there are better options usually. If you want to consider
this, you’ll want to research further before deciding.
And it refers a couple times to:
From all my research and personal testing, the available evidence indicates that picaridin and DEET are both effective at repelling black flies, while DEET is more effective at preventing tick bites. Conversely, picaridin seems to be better at repelling other biting insects, notably no-see-ums. Most others are mostly useless or require reapplying every 20 to 6 minutes. Others are only effective while you are applying them (the mosquitoes can’t bite while you are moving your hand along your arm!)