WATSONVILLE -- They are often poor, undocumented and find it harder than most Californians to access health care.
But Latinos who live in southern Santa Cruz County have higher vaccination rates and a dramatically lower incidence of whooping cough than the more affluent white population in the northern end of the county, according to data reported by schools and the county health department.
While that may seem paradoxical, state and local health officials and other experts say it illuminates a little-noticed trend that has surfaced during the state's latest whooping cough epidemic.
"One thing you will find pretty much across the state is that Latinos tend to have the highest vaccination rates -- they do really well when it comes to vaccinating their children,' " said the state's epidemiologist, Dr. Gil Chavez, deputy director of the California Department of Public Health.
And that has resulted in a lower incidence of whooping cough among Latinos in most age groups since the outbreak began more than seven months ago.
More whites get ill
Of the 70 whooping cough cases recorded in Santa Cruz County since Jan. 1, the county health department said, 42 victims are white and 25 are Latino in a county that is about 60 percent white and a third Latino.
Only four cases were reported in Watsonville, but 29 cases cropped up in Santa Cruz -- a city of 63,000 at the northern side of the county that is only slightly more populous than Watsonville.
Chavez said some of the same reasons why vaccination rates are higher among Latinos in Watsonville are true elsewhere in California. They include "a culture of vaccination" many learned in their native countries, and are less inclined to file "personal belief exemptions."
The exemptions allow parents -- for religious and other reasons -- to opt out of state-mandated vaccines for their children, which experts say leave those children at greater risk of contracting and spreading infectious diseases.
Personal exemption rates continue to rise across the state. According to data compiled by kidsdata.org, a program of the Lucile Packard Foundation for Children's Health, the state has witnessed a 42 percent increase -- from 11,868 to 16,817 -- in exemptions since 2011.
In Santa Cruz County, kindergarten immunization data for the 2013-14 school year revealed that schools that are heavily Latino almost all had vaccination rates of more than 90 percent. But mostly white schools had rates far below that.
Waiting recently inside Watsonville's Salud Para La Gente clinic for her 2-month-old son Michael's vaccination appointment, Alejandra Arias, 27, said the exemption route is not for her.
The U.S.-born mother of four boys said immunizations at the community health clinic have always been part of her family's tradition, starting when her parents took her to the clinic. And even when the family returned to live for short periods in Mexico, "they kept up with our vaccines -- and I have proof," she said, pointing to a small indent on her arm left by a smallpox vaccination she received across the border as a youngster.
Chavez can point to his own evidence: A 2010-11 survey showed that by age 2 Latino and Asian toddlers have higher rates of overall immunization -- 72.7 percent and 72 percent, respectively -- than white toddlers, at 68.6 percent. African-American toddlers have the lowest rate, at 61.2 percent. A newer survey is expected to show the same results, state health officials said.
Experts say the high rate for Asians is likely because first- and second-generation Asian-Americans, like Latinos, are more likely to respect their medical providers' advice. The lower rate for blacks, experts say, is likely due to less access to health care services and misconceptions about immunizations.
For the first time, California data on exemptions by race and ethnicity are now being compiled and will be available in several months, state health officials say. But Dr. James Cherry, a professor of pediatrics at the UCLA School of Medicine, predicts it will parallel Santa Cruz County's data.
The 84-year-old Cherry, whose textbook on pediatric infectious diseases continues to be used by health experts worldwide, said Latinos "are more likely to go along with the general health policy recommendations of doctors they see."
Studies have shown that white, college-educated, more affluent parents are more likely to believe theories that vaccines can cause autism -- theories that have been debunked.
California has so far recorded 5,393 cases of whooping cough -- more than double the 2,532 reported for all of last year. And once again, in every age range but one, whites outpace Latinos, Asians and African-Americans in the frequency of whooping cough cases.
The difference between whites and Latinos is particularly striking in the 10- to 17-year-old age range, one of the groups hardest hit by whooping cough. Data showed that the rate of white teenagers who have contracted the disease this year is more than double that of Latino teens.
But state public health data showed that among Latino babies less than a year old, whooping cough cases in 2014 are soaring -- just as they did in 2010. That year marked the state's worst whooping cough epidemic in decades, and nine of 10 babies who died that year were Latino.
Rate among infants
Dr. Maria Elevado, a pediatrician at Salud Para La Gente, said one of the reasons so many Latino babies contract the disease is that they live in large households.
"They usually come from close-knit family units where they can live with unvaccinated aunts, uncles and grandparents," Elevado said.
This year, three California babies so far have died of the disease, though health officials have not identified their gender or ethnicity.
Infant deaths from whooping cough since 2010 are the reason why public health departments are now encouraging pregnant women to get a whooping cough vaccine in their third trimester, when it can still be absorbed by the unborn baby until the first vaccine as early as 6 weeks old.
Arias, the Latina who was waiting at the Watsonville clinic, said she couldn't remember if her ob-gyn had recommended the vaccine in her last trimester.
But she said she would have done so.
"I choose to go with what the doctors say," said Arias, who works in a Santa Cruz nursing home. "And as a parent, you want what's best for your children."
Contact Tracy Seipel at 408-920-5343. Follow her at Twitter.com/taseipel.
Total cases reported through mid-July: 70
By city of residence:
Aptos -- 6
Boulder Creek -- 1
Capitola -- 5
Corralitos -- 1
Felton -- 1
La Selva Beach -- 1
Mount Hermon -- 1
Santa Cruz -- 29
Scotts Valley -- 8
Soquel -- 11
Watsonville -- 4
UNKNOWN -- 2
Total -- 70
North County (including Santa Cruz and San Lorenzo Valley): 40
Midcounty (Aptos, Capitola, Soquel): 22
South County (Corralitos, La Selva Beach, Watsonville): 6
Source: Santa Cruz County Health Services Agency