A calm guide to symptoms, how dengue spreads, where risk can appear in California, and simple mosquito bite prevention.
Dengue is a virus spread by Aedes mosquitoes. In California, most cases are linked to travel, but small pockets of local spread have happened. Know the common symptoms, watch for warning signs after fever improves, and use simple bite prevention. Dump standing water weekly, use an EPA registered repellent, and seek medical care fast if severe signs appear.
A quick story so this feels real
The first time dengue felt personal to me was a text from a friend who had just come back from a trip. Fever, headache, and this weird deep ache like their joints had been replaced with crunchy gravel.
My friend did not want drama. They wanted a clear answer.
That is how I want this to feel for you too. Calm, practical, and focused on what you can do today.
Dengue is not something I want you to panic about in California. But it is something I want you to recognize quickly, because early choices can matter a lot.
What dengue is in plain language
Dengue is a virus. It spreads mainly through the bite of certain mosquitoes called Aedes.
These mosquitoes are not the classic dusk only mosquitoes many of us picture. Aedes can bite during the day. They also love living close to people, often around homes and apartments.
Most people infected with dengue never feel sick. When symptoms do show up, dengue can look like a strong flu at first. In a smaller number of cases, dengue can become severe and needs urgent medical care.
The goal is simple
Reduce bites, spot symptoms early, and know when to seek help.
Dengue in California right now
Here is the big picture using numbers that California public health has shared.
In California, dengue infections are reported every year. Most are connected to travel, meaning a person was likely infected outside California and then diagnosed after coming home.
Local transmission means a person likely got dengue from a mosquito bite in California, not from travel. This has been rare, but it has happened.
California public health reporting listed these totals
2023 total 250 cases with 2 locally acquired
2024 total 720 cases with 18 locally acquired
2025 total 169 cases with 6 locally acquired as of December 23 2025
Those locally acquired cases were noted in a few Southern California counties in the statewide table, including Los Angeles County in 2024 and 2025, plus San Diego County and San Bernardino County in 2024.
What I want you to take from this is not fear. It is awareness.
Local spread can happen when the ingredients line up
An infected person nearby plus Aedes mosquitoes active in that area.
How dengue spreads and why it can pop up in one neighborhood
Dengue usually does not spread directly from one person to another.
A mosquito becomes infected when it bites a person who has dengue virus in their blood. After the virus grows inside the mosquito for about a week, that mosquito can pass dengue to another person in a later bite.
That is why one practical tip matters so much
If you might have dengue, do your best to avoid mosquito bites for about a week after symptoms start. This helps protect your neighbors too, because it reduces the chance that local mosquitoes pick up the virus and continue the chain.
Where risk can appear in California
Risk is not evenly spread across California. It follows the mosquitoes.
California public health has noted that the mosquitoes that can spread dengue are present in some areas of the state, especially parts of Southern California and the Central Valley. Local mosquito control districts also track where these mosquitoes are established.
Here is how I picture it
Dengue risk in California is usually a spark risk, not a wildfire.
Most of the time, the spark does not have fuel. But in warmer months, in places where Aedes mosquitoes are active, a travel related case can return home and briefly create the conditions for local spread.
Things that raise the chance of that spark
Warm seasons and warm pockets
Aedes mosquitoes do well in warmth. Even within one city, sunny patios and sheltered corners can create little warm zones.
Lots of tiny water containers
Aedes mosquitoes can breed in very small amounts of water. Think plant saucers, a forgotten toy bucket, a clogged gutter corner, or water trapped in a tarp fold.
A travel link
Because most California cases are travel associated, recent travel is a big clue when fever shows up.
Dengue symptoms and the timeline I want you to remember
Dengue has a timing pattern that helps you make smarter decisions.
Symptoms often start about 5 to 7 days after an infected bite, though it can be as short as 3 days or as long as 10 days.
Many illnesses can cause fever and body aches. What makes dengue tricky is that the danger window for severe dengue can open right as someone seems to improve.
In other words, fever goes down does not always mean risk goes down.
Common dengue symptoms
These are the symptoms public health agencies highlight most often
Fever
Headache
Pain behind the eyes
Muscle and joint pain
Nausea
Rash
Some people also feel wiped out and light sensitive, like the world is too loud.
Here is a simple table you can screenshot mentally.
| What you feel | What it might mean |
|---|---|
| Fever and aches and headache | Common early dengue pattern, also common in other viruses |
| Rash a few days in | Can happen in dengue, especially as fever changes |
| Vomiting and not keeping fluids down | Higher risk of dehydration, needs medical advice |
| New belly pain after fever improves | Warning sign, get urgent care |
Warning signs that mean get emergency care now
Health agencies list warning signs that can show up around the time fever starts to go away.
If you see these, I would not wait it out at home.
Belly pain or tenderness
Vomiting at least 3 times in 24 hours
Bleeding from the nose or gums
Vomiting blood or blood in stool
Feeling extremely tired, weak, restless, or confused
If you are caring for a child, trust your gut. A child who is unusually sleepy, hard to wake, or not drinking should be checked urgently.
What to do if you think you might have dengue
I like clear steps, so here is my calm checklist.
Step 1 Contact a clinician early
If you have fever plus dengue like symptoms, reach out for medical advice. Tell them about recent travel and mosquito exposure. That context helps a lot.
Step 2 Use the safer fever medicine choice
Public health guidance commonly recommends acetaminophen for fever and pain when dengue is possible.
They also commonly advise avoiding aspirin and ibuprofen until dengue is ruled out, because these medicines can increase bleeding risk.
If you are unsure what is safe for you, especially if you are pregnant or have liver disease, ask a clinician.
Step 3 Hydrate like it is your job
Fever and vomiting can dry you out fast. Sip water often. Oral rehydration drinks can help when nausea is in the picture.
If you cannot keep fluids down, that is a reason to seek care.
Step 4 Avoid mosquito bites while sick
This one feels small but it matters.
If you might have dengue, use repellent and stay in screened or air conditioned spaces so mosquitoes do not bite you and pick up the virus.
My bite prevention plan for California homes
This is where you get real control.
Aedes mosquitoes are not strong flyers. They often stay close to where they hatch. That means your yard, patio, and block matter.
The weekly water dump
Once a week, I do a fast walk around the outside of my place. Two minutes is enough if you keep it simple.
Dump and scrub anything that holds water, even a little.
Plant saucers
Buckets and watering cans
Kids toys
Pet bowls left outside
Tarps and covers
Clogged gutters
Old tires
Water that collects in outdoor furniture parts
If a container must stay outside, flip it over or store it indoors.
The scrub part matters because mosquito eggs can cling to the sides of containers.
Make the indoors boring for mosquitoes
Repair window screens. Check doors for gaps. If you can, use air conditioning during heavy mosquito months so you can keep windows closed.
If you like fresh air, a fan near a doorway can help push air outward and make it harder for mosquitoes to drift inside.
Repellent that actually works
I stick with products that public health and environmental agencies repeatedly recommend when used as directed.
Look for an EPA registered repellent with one of these active ingredients
DEET
Picaridin
IR3535
Oil of lemon eucalyptus
One important note
Oil of lemon eucalyptus used in repellents is not the same as lemon eucalyptus essential oil. Public health guidance also commonly says oil of lemon eucalyptus products are not for children under 3.
My simple repellent routine
Put it near your keys so you remember
Apply sunscreen first, then repellent
For kids, spray on your hands first, then rub on their skin
Avoid eyes and mouth
Wash treated skin after you come inside
Clothing and timing
Because Aedes can bite during the day, I treat daytime outdoor time like it counts.
If you will be outside for a while, wear loose long sleeves and long pants. Light colors can make it easier to spot mosquitoes on fabric.
For babies and toddlers, physical barriers are amazing. Stroller netting and properly fitted screens do a lot with zero chemicals.
Yard habits that cut bites
This is not about having a perfect yard. It is about removing mosquito hiding spots.
Trim dense plants near doors
Store items so water cannot pool
Keep outdoor trash bins closed
If you have a birdbath, refresh it often and scrub it
Travel is still the biggest dengue driver for California
Because most California cases are connected to travel, travel is where your personal risk usually climbs the fastest.
Before traveling to places where dengue is common
Pack repellent you will actually use
Pack light long sleeves for day outings
Choose lodging with screens or air conditioning
Remember daytime bites count too
When you return home
If you get a fever within about two weeks after travel, mention your travel history when you talk to a clinician. Dengue should be on the list of possibilities.
What about a dengue vaccine for people in California
Online vaccine talk gets messy fast, so here is the clean version based on US public health guidance.
The dengue vaccine available in the United States has had a narrow recommended use. Guidance has focused on certain children who have lab confirmed prior dengue infection and who live in places where dengue is common, mainly certain US territories, not most of the continental United States.
There have also been announcements about discontinuation that can affect availability over time.
For most families in California, the practical focus remains the same
Prevent bites and recognize symptoms and warning signs.
A simple today list you can actually do
If you want the shortest possible plan, here it is.
Dump standing water around your home today
Fix one screen or one door gap this week
Put repellent where you keep your keys
Teach kids the quick rule shoes on then repellent on
If fever happens after travel, call a clinician and avoid ibuprofen until dengue is ruled out
You do not need perfection. You need a few habits that stick.
And if you ever want a weird mosquito nerd secret from me
The weekly water dump is the one that makes the biggest difference for most homes. It is boring. It is not a shiny gadget. It works.
Key Facts
- Dengue is spread mainly by Aedes mosquitoes that often bite during daytime hours.
- In California, most dengue cases are linked to travel, but local transmission has occurred.
- California reported 18 locally acquired cases in 2024 and 6 in 2025 as of December 23 2025.
- Aedes mosquitoes can breed in small containers of water around homes.
- Dengue symptoms can include fever, headache, eye pain, body aches, nausea, and rash.
- Warning signs can appear after fever improves and may signal severe dengue.
- Acetaminophen is commonly recommended for fever when dengue is possible.
- Avoid aspirin and ibuprofen until dengue is ruled out due to bleeding risk.
- If you might have dengue, avoid mosquito bites during the first week of illness.
FAQ
Is dengue common in California
Most reported cases are travel associated. Local transmission is rare but has happened in recent years.
Where can dengue risk show up in California
Risk can appear where Aedes mosquitoes are established, especially parts of Southern California and the Central Valley. Local spread needs both mosquitoes and a nearby infected person.
What are the first symptoms of dengue
Many people start with fever plus headache and body aches. Some also get pain behind the eyes, nausea, or a rash.
When should I go to the ER for dengue
Go right away if warning signs appear, especially after fever improves. Belly pain, repeated vomiting, bleeding, or extreme weakness are red flags.
Can dengue spread from person to person
Usually no. Dengue typically spreads when a mosquito bites an infected person and later bites someone else.
What medicine is safer if dengue is possible
Public health guidance often recommends acetaminophen for fever and pain. They also advise avoiding aspirin and ibuprofen until dengue is ruled out.
How do I protect my family at home
Dump standing water weekly, repair screens, and use an EPA registered repellent when outside. Aedes mosquitoes often breed in small containers around the home.
If I am sick, how do I avoid spreading dengue locally
Prevent mosquito bites during the first week of illness by using repellent and staying in screened or air conditioned spaces. This helps stop mosquitoes from picking up the virus.
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