By Carol A. Kemper, MD, FACP

Clinical Associate Professor of Medicine, Stanford University, Division of Infectious Diseases, Santa Clara Valley Medical Center

Dr. Kemper reports no financial relationships relevant to this field of study.

Pet Snake Snacks: A Salmonella Treat

SOURCE: Marin C, Martelli F, Rabie A, Davies R. Commercial frozen mice used by owners to feed reptiles are highly externally contaminated with Salmonella enteritidis PT8. Vector Borne Zoonotic Dis 2018;18:453-457.

Who would imagine those little pink mice that people feed to their pet snakes and reptiles are highly contaminated with Salmonella? It turns out, these innocent-looking, little, pink bodies may be responsible for repeated outbreaks of Salmonella infections in the United States and in the European Union. Two larger outbreaks have been ongoing for many years, due to Salmonella enteritidis or Salmonella typhimurium, and have been linked to ownership of pet snakes and other reptiles. A common food source for many pet reptiles is feeder mice, which are commercially raised, frozen, packaged, and shipped throughout the world. Evidence points to frozen feeder mice as the source of reptilian Salmonella infection. In 2008, Salmonella infections were linked to a small commercial feeder mouse facility in Georgia, which recalled millions of frozen mice in 2010. Molecular analysis has revealed that another sustained outbreak of S. enteritidis infection from 2012-2015, resulting in more than 400 infections, also likely was secondary to feeder mice. During this outbreak, more than 40% of the infections occurred in children ages 10 years or younger; 30% of those affected owned pet snakes or reptiles.

Feeder mice are shipped frozen and packaged in large bags, and often are kept in the family freezer. Many owners find using frozen mice simpler to manage than trying to run back and forth to the pet store for live mice every time their snake is hungry. Even more damning, owners often thaw the mice by microwaving them or heating them in a pan of water on the stove-top, so their pet snake can have a warm treat (rather than a mouse ice-pop). Reptiles become colonized with Salmonella but seldom become ill. But they serve as a source for infection and contamination of the household environment, where the bacteria may persist in the environment for months (> 12 months in some studies).

In the United States, commercial facilities that distribute frozen mice are required to place safe handling labels on packages. In the United Kingdom, snakes are not considered pets; therefore, feeder mice are not considered “pet food,” so specific labeling is not required.

These researchers examined 295 feeder mice for evidence of Salmonella colonization of the integument and internal organs. Different types and sizes of feeder mice, including fuzzies, pinkies, small, large, and extra-large mice, were processed and cultured in 12 batches of five mice each. A batch was considered positive if any one mouse in a batch was culture-positive. Salmonella was isolated from the external carcasses of one or more mice from nearly one-third of the batches. Fuzzies showed the highest proportion of external colonization, with positive mice found in 10 of 12 batches (83.3%); five of 12 of the smaller mice batches were positive, followed by one of 12 of the batches of both the pinkies and extra-large mice. This suggests that fuzzies, which have been implicated previously, are highly externally contaminated with Salmonella relative to other mouse types.

Salmonella colonization of internal organs was found to potentially infect all organs examined (liver, spleen, kidneys, bladder, cecum, intestine; up to 5% of organs), but was found mostly in the intestines, as anticipated. Rates of colonization were similar between mouse types. Two different strain types of S. enteritidis were isolated (PT8 and PT13) and were sensitive to all 16 antimicrobial agents tested.

Radiation of feeder mice before packaging has been proposed as a way to reduce the risk of Salmonella infection, but this would not affect internal colonization. The environments of these facilities the dust, the droppings, the cages — must be persistently contaminated with Salmonella. A wholesale new approach to “growing” pet food would be required to reduce the risk of bacterial infection.

Linking HIV-positive Inmates to Outpatient Care

SOURCES: Cunningham WE, Weiss RE, Nakazono T, et al. Effectiveness of a peer navigation intervention to sustain viral suppression among HIV-positive men and transgender women released from jail. The LINK LA Randomized Clinical Trial. JAMA Intern Med 2018;178:542-553. Accompanying editorial: Metsch LR, Pugh T, Colfax G. An HIV behavioral intervention gets it right — and shows we must do even better. JAMA Intern Med 2018;178:553-555.

It is a sad commentary, as we so often noted at the county HIV clinic: Some patients did better when they were in jail. Linking jail care to outpatient care, so that former inmates can be transitioned smoothly to outpatient care and outpatient medications without being lost to care or disenfranchised, remains an important concern.

Jails have become an important focal point for detection of previously unrecognized HIV infection and recognition of persons with HIV who are not in care or who have fallen out of care. Using national surveillance data, approximately 1.5% of all persons in state and federal facilities are HIV-positive. About one-fourth of those are unaware of their HIV status, and another one-third of those who are aware of their HIV status are not in care. These data extrapolate to suggest that upward of 13,600 inmates per year do not receive HIV medical care once released to the community.

Getting these individuals into medical care and keeping them there is critical. However, the reasons this may not occur are complex and variable. To frame the problem, one author identified four points where the system breaks down, as follows: lack of knowledge of HIV status; awareness of HIV status but not in care; having entered care at one point but disengaged; irregular participation in care and noncompliance with medical recommendations. Such a breakdown allows programs to identify methods for addressing the varying social and psychological barriers.

To address some of these gaps, the authors of a randomized clinical trial designed a peer navigation intervention to transition former inmates into outpatient HIV care. LINK LA trained peer navigators to work with inmates to establish goals and solve problems to establish care, secure outpatient medications, and improve medication adherence. Participants were randomized either to participate in the 12-session, 24-week intervention, beginning in jail and continuing through to the outpatient setting, or to standard traditional case management. Navigators participated in at least two outpatient clinic visits and continued to follow inmates for up to 12 months after their release. The success of the intervention was measured by one powerful endpoint: HIV virological suppression (< 75 copies/mL) at 12 months.

From 2012-2016, 356 individuals leaving Los Angeles County Jail were recruited for the project, including 303 men (82%) and 53 (15%) transgender women; 42% of these were black and 31% were Latino. At 12 months, HIV viral suppression was achieved in 62/125 (49.6%) of the participants in the intervention arm vs. 45/125 (36%) of those in the control arm. In an adjusted model for repeated measures, viral suppression was much better maintained in those in the intervention arm than the control arm. Virological suppression declined from 52% at baseline to 49% at 12 months in the intervention group compared to 30% among controls, for a difference-in-difference of 22% (P = 0.02).

LINK LA successfully steered many former inmates into care, and nearly half of study participants in the intervention arm had sustained virologic suppression one year later. For anyone who has attempted behavioral/adherence trials, these results are remarkable, especially with this patient group and even more so that the results were sustained for one year. And yet, despite a high level of personalized attention, just less than half of those in the intervention arm achieved their treatment goal. Half is a long way from the national goal of > 90% virologic suppression. It is unclear whether expanding such a program would be feasible financially and what more would be required to bring outliers into care.