While much attention is focused on influenza this time of year, San Diego public health officials are also monitoring other infectious diseases that may be on the rise this month and through 2020.
Outbreaks of communicable diseases can often be unpredictable but some illnesses are seasonal or cyclical and can be prevented. A county health department director warned instances of a common sickness could become more severe this winter, and the region may be headed toward a spike of a vaccine-preventable illness, which can be fatal to infants.
Dr. Eric McDonald, director of San Diego County’s epidemiology and immunization services branch, said he expects this month to see more outbreaks of norovirus. Cases typically peak by February, but the region may see an even greater surge this season because a new strain of the disease circulates every few years.
"We’re sort of due for one of those to kind of really get us," McDonald said.
A new strain of norovirus, which causes diarrhea and vomiting, is expected about every two to four years, according to the Centers for Disease Control and Prevention. But the current variety that McDonald said is causing the majority of outbreaks, known as GII.4 Sydney, emerged in 2012.
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McDonald said he is also concerned about an increase in whooping cough, or pertussis, because outbreaks of the disease occur about every three to five years and the county's last major outbreaks were in 2014 and 2010. The latter marked California's biggest outbreak in 60 years.
"We're concerned because whooping cough is potentially life-threatening for children under 12 months, especially under 4 months," he said.
The county also experienced a spike in 2017. McDonald said part of the problem is low immunization rates among pregnant women. Vaccination during pregnancy helps protect an infant against the deadly disease until babies can receive their series of shots which begin around two months old.
A 2016 state survey found about half of pregnant women received the pertussis vaccination. California health officials urged prenatal providers in an April advisory to vaccinate all pregnant women after an Orange County infant was the first to die from the disease that year.
However, McDonald said San Diego County has seen an increase in pertussis cases over the last two years, so it's unclear if the growth is a new normal or leading to an outbreak.
For norovirus — which is often known as the "stomach flu" but is not caused by the influenza viruses — there is no vaccine to prevent spreading the disease, but McDonald said staying home when sick and practicing basic hygiene is key.
"Do the things your mom told you: wash your hands before eating and after going to the bathroom," he said.
He also suggested people use fist bumps instead of physical touch during the winter.
"It gives a good chuckle but it probably really helps," he said.
Last fiscal year, county officials investigated 35 norovirus outbreaks — below the five-year average of 46 — with a range of two to 321 cases for each event. Facilities are only required to report norovirus outbreaks, defined as at least two laboratory-confirmed cases, and not individual incidents.
