CorrectCare

Mumps! A Jail Outbreak and Public Health Response

by Lillian Ringsdorf, MD, Bret Heerema, MD, MPH, Jessica Ruiz, BSN, RN, and Roger Sanchez

From July through September, 2010, an outbreak of 28 confirmed cases of mumps occurred in the Bexar County Jail in San Antonio, TX. The entire county, which has a population of more than 1.6 million, typically reports one or two cases per year. The jail consists of 12 pods with an average daily population of 3,500. Other outbreaks of mumps have been reported in Iowa in 2006 and in New York and New Jersey in 2009 despite high levels of vaccine coverage in the United States. The viral strain in all three of these outbreaks was genotype G. This article outlines the Bexar County Jail outbreak and the public health response to investigate and contain it.

The first two suspected cases presented to jail health care workers on July 15 for jaw swelling and fever. No immediate diagnosis was made, but the individuals were placed in isolation to prevent the spread of a potentially contagious disease. Two days later, the inmates were transferred to a local hospital for precautionary and investigative reasons where they were presumptively diagnosed with mumps. Local health officials were notified of these infections on July 20 as well as four similar cases at the jail. Public health officials recommended that jail authorities immediately isolate both these and future suspected cases (anyone presenting with jaw or upper neck swelling on one or both sides corresponding to the parotid or other salivary glands) for nine days or until infection was ruled out. Furthermore, the pods from which the affected inmates had come were to be quarantined for 25 days past the date of symptom onset.

The Centers for Disease Control and Prevention defines a confirmed case of mumps as any individual with two or more days of parotitis and either positive labs or a direct link to a confirmed case; therefore, mumps should not necessarily be ruled out by negative labs. The CDC guideline committee that investigated the 2006 mumps outbreak recommended isolation of cases for only five days following parotitis onset since the risk of transmission after this time is low. However, studies have shown that patients may still shed virus up to Day 9 in 4% of the population. Although individuals are generally considered infectious for three days prior to parotitis, the virus has been isolated up to seven days prior to symptom onset.

In the jail inmate population, however, medical histories are considered notoriously poor and inmate contact tracking is complicated. Thus, the infectious period, used to identify contacts of cases for quarantine, was defined as five days prior to symptom onset and nine days following.

The average incubation period for mumps is 16 to 18 days from exposure to onset of symptoms, but can be as much as 25 days. Additionally, 15% to 20% of all infected individuals are asymptomatic, more commonly in adults, and up to 50% of individuals infected have nonspecific, flu-like symptoms. Hence, the diagnosis is easily missed. Plus, transmission of the virus is greatly facilitated in situations in which prolonged close contact occurs.

For all of these reasons, control measures can be quite difficult. San Antonio public health officials decided to take a conservative approach to the outbreak due to the close and crowded quarters in the facility and recommended a full nine days of isolation and 25 days of quarantine.

The Contact Investigation Begins
Laboratory confirmation of mumps infection for the first two cases was obtained on July 23 and public health officials performed a formal contact investigation at the jail that same day. During the contact investigation, public health officials noted that infected inmates had been in contact with multiple pods prior to isolation while they were suspected of being infectious. Thus, these additional pods were also placed under quarantine.

Over the next two months, 22 more cases of mumps were identified; 13 of these were restricted to Bexar County Jail, including two employees. Two had been transferred from the jail to the Mentally Impaired Offenders Facility and two were employees at the MIOF. The contact investigation involved home visits of released inmates who had spent time in one of the quarantined pods during the infectious time periods. While no new cases were identified in this way, a local hospital reported that a noninmate female had been diagnosed with mumps. Upon questioning by public health officials, she admitted to contact with a jail inmate. Four more cases of mumps were identified at an intermediate sanction facility, three of whom had previously spent time at the Bexar County Jail in quarantine. Such transfers were allowed and accepting facilities completed the 25-day quarantine.

A Coordinated Response
Conference calls between local health officials and the Texas Department of State Health Services, the Bexar County Jail and the Texas Department of Criminal Justice began on Friday, July 23, and open lines of communication between these agencies continue through the time of this writing. Area weekly emergency preparedness meetings were also informed of developments starting July 26. The DSHS distributed “Mumps Fact Sheets” and “Control Measures” to all involved agencies on July 27. The strategies implemented after coordination between these entities were to define the at-risk population, keeping that population as confined as possible and immunizing those at risk. (See General Recommendations above.)

Except for the index cases who were transferred to a hospital for diagnosis, affected inmates required only symptomatic treatment. None of the identified cases during the jail outbreak involved serious complications such as meningitis, although six did suffer from orchitis (testicular inflammation causing pain).

Prior immunization with at least one mumps, measles and rubella (MMR) vaccination was documented for 10 of the cases. An additional 10 individuals were educated in the Texas public school system, where vaccination is mandatory. The development of disease in previously immunized individuals was reported in the 2006 and 2009 outbreaks, as well. Investigations into the 2006 mumps outbreak found that individuals who had received two doses of MMR vaccine had significantly lower infection rates than those who had received just one. The CDC’s Advisory Committee for Immunization Practices has since issued new guidelines stating that acceptable vaccination now requires two doses for high-risk individuals. MMR effectiveness is estimated to be between 73% and 91% for one dose and 76% to 95% for two doses. Although immunization after exposure to mumps has not been demonstrated to be protective, the CDC recommends vaccination for susceptible individuals with no history of vaccination or one dose only.

Because of this recommendation and the realization that previous vaccination status was difficult to confirm in this population, the Texas DSHS recommended vaccination of all exposed inmates with one dose of MMR vaccine. The vaccinations were administered on July 27 to consenting inmates in quarantined pods; very few refused vaccination. On July 28 and 30, jail employees were offered the vaccine on a voluntary basis.

Because of the long incubation period for mumps, cases were expected to continue to occur even among newly vaccinated persons who may have been infected before vaccination. This situation occurred with one of the MIOF employees, who was vaccinated and then was diagnosed with mumps two and a half weeks later. Thus, a surveillance period of 50 days, two incubation periods, after the last known case presentation has been implemented to allow for identification of transmission from subclinical infections. At the time of this writing, this surveillance period has not concluded and sporadic cases are expected for at least another month.

Lessons Learned, Lingering Questions
Management of an outbreak such as this presents many challenges. In reviewing the series of events, agencies can learn lessons that will improve future responses. One lesson from this outbreak is that early communication and collaboration among medical staff, facility administration and public health officials is essential. Face-to-face communication has proven most effective and should be arranged whenever possible to avoid misunderstandings. Open communication with the inmate population is important, as well, to elicit early reporting of symptoms to facilitate disease control. In addition, early establishment of the communication hierarchy in affected institutions and agencies is crucial. Identification of the appropriate supervisors with whom to communicate will ensure a smooth working relationship among all involved.

This outbreak raises a compelling issue regarding disease prevention measures among the inmate population. Should inmates be vaccinated for hepatitis B given the fact that this population is well known to be at increased risk for infection? Should inmates be vaccinated for influenza to prevent an outbreak? Should entrance screening be more extensive? Outbreaks in correctional facilities are costly in terms of staff overtime, staff sick days, supplies and space restrictions, all of which should be included in any analysis of the cost-effectiveness of prevention programs. This outbreak presents an opportunity for correctional officials to reassess the preventive measures currently in effect.

— About the authors: Lillian Ringsdorf, MD, is with the University of Texas Health Science Center, School of Public Health, Houston; Bret Heerema, MD, MPH, is with the U.S. Air Force, Brooks City Base, San Antonio; Jessica Ruiz, RN, BSN, and Roger Sanchez are with the San Antonio Metropolitan Health District.

[This article first appeared in the Fall 2010 issue of CorrectCare.]