Invasive Meningococcal Disease (IMD) in San Diego County in 2013
Date: August 9, 2013
Thirteen (13) San Diego County residents have been diagnosed with confirmed or probable Invasive Meningococcal Disease (IMD) during the first seven months of this year. Nine confirmed cases were culture-positive for Neisseria meningitidis. Four probable cases had clinical disease and positive PCR testing for N. meningitidis after no culture growth. Since 2003, the number of confirmed or probable IMD cases reported annually among San Diego County residents ranged from 4 to 19, with an average of 12.
Recent IMD cases emphasize the need for both clinicians and laboratories to report suspect cases in a more timely fashion, allowing public health officials to prevent secondary cases by facilitating rapid post-exposure prophylaxis (PEP). Household and other close contacts of confirmed, probable, or clinically suspect cases should receive PEP as soon as possible — regardless of meningococcal vaccination status — as not all circulating strains are covered by the vaccine. Ideally, PEP should occur within 24 hours of case identification or strong clinical suspicion. The Epidemiology Program may also arrange PCR testing for detection of meningococcal and pneumococcal DNA when patients with suspected bacterial meningitis are culture-negative. Details of some recent cases include:
- A 17-year-old male presented to an emergency department (ED) on June 29 after several outpatient visits with symptoms including fever, emesis, petechial rash, and mild headache. He had received meningococcal vaccine at age 16. CSF studies were not consistent with bacterial meningitis; however, blood cultures were positive for gram-negative coccobacilli on June 30. The suspect case was reported on July 1, and PEP was recommended to 61 close contacts, including 58 high school football players and coaches. Blood cultures grew N. meningitidis serogroup B, which is not covered by the meningococcal vaccine.
- A 17-year-old male teammate of the previous case presented to an ED on July 2 with fever, headache, and stiff neck. He had also received meningococcal vaccine at age 16. Despite reporting a shared drink with the previous case, he was discharged without PEP after CSF and blood studies were obtained. He was recalled on July 3 for treatment when blood cultures started to grow bacteria, subsequently identified as N. meningitidis serogroup B. Parents of other football players later reported that some players had not received PEP because their healthcare providers incorrectly believed that meningococcal vaccination was fully protective for all circulating strains. Other parents delayed filling PEP prescriptions because they were not instructed about the time-sensitive benefit of prophylaxis.
- A 33-year-old male was admitted on July 15 with symptoms including fever, severe headache, and emesis. Gram-negative diplococci were observed on a blood gram stain on July 16. The case was not reported until July 19, after final blood culture results were positive for N. meningitidis, delaying a PEP recommendation to a close contact. The isolate was subsequently identified as N. meningitidis serogroup C.
- A 29-year-old female was admitted on July 16 with symptoms including fever, emesis, and petechial rash. Meningococcemia was suspected on admission, but the case was not reported until July 18, delaying PEP recommendations to 27 close contacts. Antibiotics were administered before blood and CSF specimens were obtained. No cultures had bacterial growth, but PCR testing facilitated by the Epidemiology Program detected N. meningitidis serogroup C in both the blood and CSF.
- An 89-year-old female was admitted on July 27 with symptoms including fever, headache, and stiff neck. CSF cell counts were suspicious for bacterial meningitis, gram-negative diplococci were observed on the CSF gram stain, and meningococcal meningitis was the primary admission diagnosis. The case was reported on July 29 and PEP was subsequently recommended to a close contact. All cultures were negative, but PCR testing detected N. meningitidis serogroup B in the CSF.
In March 2013, the Centers for Disease Control and Prevention (CDC) published updated recommendations on the prevention and control of meningococcal disease. The California Department of Public Health (CDPH) published updated guidance on their website last month on meningococcal disease.
Specific reminders regarding meningococcal disease for local healthcare providers include:
- Maintain a high index of suspicion for meningococcal disease when evaluating patients with fever and petechial or purpuric rash.
- Immediately report suspect meningococcal disease by telephone to the Epidemiology Program. Healthcare providers should immediately report clinically suspect cases and not wait for culture results. Laboratories should immediately report gram-negative diplococci from any sterile site (e.g., blood, CSF, pericardial fluid, synovial fluid), as well as confirmation of N. meningitidis from any culture source. The Epidemiology Program can be contacted by calling (619) 692-8499 during normal business hours (Monday–Friday 8:00am–5:00pm), or (858) 565-5255 after hours and on weekends.
- Remember that PCR testing can be more sensitive in detecting N. meningitidis than routine cultures, especially if specimens are collected after antibiotic administration. CSF is sterile as soon as 15 minutes after parenteral antibiotic administration (and likely to occur soon after oral antibiotic therapy). PCR testing can be arranged for clinically compatible cases by contacting the Epidemiology Program.
- Provide post-exposure prophylaxis (PEP) to household and other close contacts regardless of prior vaccination status because available meningococcal vaccines do not provide protection against N. meningitidis serogroup B and vaccine immunity for other serogroups wanes. The quadrivalent meningococcal conjugate vaccine (MCV4) provides protection starting 7–10 days after vaccination against serogroups A, C, W-135, and Y. It does not protect against serogroup B. Approximately 30% of all meningococcal disease cases in California are caused by serogroup B. Meningococcal vaccine is routinely recommended for children and adolescents 11–18 years of age, with an initial dose at age 11–12. Because immunity wanes over time, a booster is recommended at age 16. Click here for more vaccine information.
- Ensure timely and appropriate antibiotic coverage when prescribing meningococcal PEP. Prophylaxis should be implemented as soon as possible, ideally within 24 hours of case identification or strong clinical suspicion. Prophylaxis should be offered up to 14 days after the last exposure. Ciprofloxacin is routinely recommended as PEP for people 18 years of age and older. Per 2011 AAP recommendations, a single dose of ciprofloxacin (20 mg/kg) can be considered for those >1 month of age based on a risk / benefit assessment. CDPH and CDC consider it reasonable to use single-dose ciprofloxacin for N. meningitidis chemoprophylaxis in children >5 years of age given that reports of adverse events have been rare after widespread use in children. Rifampin, 20 mg/kg/day, in two equally divided doses for 2 days (4 doses total), is the preferred alternative to ciprofloxacin for children one month through 5 years of age. Click here for more information about PEP recommendations.
- Be aware of continuing reports of meningococcal disease in men who have sex with men (MSM). MSM who travel to New York City or to Europe should be aware of the signs and symptoms of meningococcal disease because of recent case clusters reported in these locations. Vaccination before travel to these areas should be offered to MSM based on an individual assessment of risk. Although no IMD cases in MSM have been reported recently in San Diego County, obtain travel and sexual histories when evaluating individuals with possible IMD. Click here for more information.