Chikungunya fever just turned up again in South Carolina, in an Upstate resident who recently returned from Haiti. The virus showed up last year in Charleston County, also in a returning traveler.

The African disease now joins a handful of other mosquito-borne diseases in the Lowcountry that have two things in common:

The odds are low that you will get one of them or have any symptoms if you do.

If you do get symptoms, there are no treatments.

That's why you should care enough to take precautions.

"The chance is extremely low," said Michael Schmidt, Medical University of South Carolina microbiology and immunology professor. But it's not worth disregarding. Chikungunya, for example, "makes you feel like your bones are breaking," he said

"Any of these insects that have blood meals, the virus (if the insect carries it) is very small, so you get a large dose in a small volume. The treatment is simply supportive care, which is why the best treatment is prevention. The mosquito abatement programs are money well spent," Schmidt said.

Prevalence

Face it, there's billions of mosquitoes out there during outbreaks, usually a few days after a rain; the insects lay eggs in water and eggs tend to hatch when submerged.

Because of sporadic rains this summer, it has been a lighter-than-normal season for hatches - so far, said Donna Odom, Charleston County mosquito control manager. But that could change after recent thundershowers. "It's that time of year," she said.

Precautions

Insect repellents, long sleeved clothing. Dump or drain standing water.

Here are some repellents:

DEET: Diethyl-meta-toluamide: Accept no substitute, most mosquito pros say. DEET worked better and longer in scientific trials, according to the Centers for Disease Control and Prevention.

Picaridin: A synthetic compound made in the 1980s but not widely in use in the U.S.

Lemon eucalyptus oil: Plant product recommended by the CDC.

IR3535: Found in some common commercial repellent products instead of DEET.

The most prevalent South Carolina diseases:

West Nile virus

Cases: 26 in South Carolina from 2010-2014; 4 in Charleston, Berkeley or Dorchester counties.

Symptoms: Most people, none. Otherwise, fever, headache, body ache, joint pain, vomiting diarrhea, rash.

Worst case: Less than 1 percent of people infected with the virus develop an encephalitis, a serious neurological illness that can lead to tremors, seizures, paralysis and death.

Treatment: None. Supportive care.

Chikungunya

Cases: 2, South Carolina; 1 local counties. Chikungunya is an African disease that recently occurred in the Caribbean and has just appeared in South Carolina. Infected persons here so far are travelers returning from those countries, but Florida just confirmed its first case of non-traveling resident getting it.

Symptoms: Most commonly, fever, joint pain. Others: headache, muscle pain, joint swelling, rash.

Worst case: Death, rarely.

Treatment: None. Supportive care.

Eastern equine encephalitis

Cases: 0, South Carolina; 0 local counties.

Symptoms: Most people, none. Others, sudden onset headache, high fever, chills, vomiting.

Worst case: Symptoms develop into seizures and coma; 33 percent chance of death or significant brain damage.

Treatment: None. Supportive care.

Other encephalitides

Cases: 4, South Carolina; 0, local counties. Most occur in children under 16 years old.

Symptoms: Most people, none. Fever, headache, nausea, vomiting, and tiredness.

Worst Case: Seizures, coma, paralysis, very rarely death.

Treatment: None. Supportive care.

Other concerns

Dengue Fever: Widely spread in the Caribbean. Thirty cases in South Carolina since 2010, most often in returning travelers. But it is has turned up in Florida. Symptoms similar to chikungunya.

Malaria: Mostly eradicated, but 34 cases have turned up in the state since 2010, most often in returning travelers. A few cases turn up in the Lowcountry from year to year, and not all of them can be traced to overseas travel, said Schmidt, of MUSC. Symptoms similar to West Nile, but malaria can be treated.

Yellow fever: Mostly eradicated; 0 cases in the state since 2010. But concern will rise with the widening of the Panama Canal and deepening of Charleston Harbor, allowing shipping to arrive here more quickly, potentially carrying mosquitoes or eggs from a region where the disease still occurs, Schmidt said.

Cats, dogs and horses

Heartworm: Not always recognized as a mosquito-borne disease.Rarely occurs in people, but 50 to 100 cases per year are reported on average in the Lowcountry in cats and dogs. Symptoms include cough, reduced appetite and weight loss.

Worst case is death. Treated by vaccine.

Eastern equine encephalitis: Primarily a horse disease. More than 80 cases in South Carolina 2011-2013, 7 in local counties. Symptoms are similar to humans and worst case is death. No treatment.

By the numbers

61: Mosquito species in South Carolina alone.

3,200: Species worldwide.

Several million: The number of mosquitoes that can hatch per acre per rainfall in a dredging disposal site.

In response to a large salt-marsh mosquito "hatch-off," Berkeley County Mosquito Abatement will be spraying by aircraft in the southern portion of the county over Daniel Island, Thomas Island, areas adjacent to Clements Ferry Road and the dredge disposal sites along Clouter Creek. The aerial application will be made on Thursday between 6:30 a.m. and 9:30 a.m. If unfavorable weather conditions exist, the applications will be made on the next suitable day. Those with questions or concerns may contact Berkeley County Mosquito Abatement at 719-4646.

Sources: S.C. DHEC, the Centers for Disease Control and Prevention, Chas. County Mosquito Abatement Program, Medical University of S.C., American Heartworm Society