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By Carol A. Kemper, MD, FACP, Clinical Associate Professor of Medicine, Stanford University, Division of Infectious Diseases; Santa Clara Valley Medical Center, Section Editor, Updates; Section Editor, HIV, is Associate Editor for Infectious Disease Alert.
WNV infection and the mortgage crisis
Source: Reisen Wk, et al. Delinquent mortgages, neglected swimming pools, and West Nile Virus, California. Emerg Infect Dis. 2008,14:1747-1749.
An outbreak of 140 human cases of West Nile Virus in Kern County, California (better known for its increased risk of coccidioidomycosis), during the summer of 2007, prompted Reisen et al to look for possible causes. Based on vector control data, there was a significant increase in WNV infection in birds in the area in June 2007, shortly followed by human cases. A total of 124 dead birds were identified, many of which were young hatchlings, which have limited immunity to WNV. Mosquito traps in June also showed a spike in WNV-infected female mosquitoes (18.5 infected mosquitos/1000).
Searching for an answer to the increased prevalence of WNV, an aerial map of Bakersfield showed a number of green pools and Jacuzzi/hot tubs in people's backyards. Based on aerial photos taken in August 2007, at least 17% of 42 pools in the immediate Bakersfield area were green. Reisen et al speculate that delinquent mortgages and abandoned homes were to blame for the neglected pools — delinquencies in the area were up 300% in 2007 compared with a year earlier.
In addition, Reisen et al note that many regulations and laws requiring owners to keep pools locked up, keep these same pools out of reach of local mosquito abatement personnel. Ordinances in our area require a surrounding 2M fence, with a locked gate, or a secured locked pool cover, so that rascals may not access the pool when the owner is not present. (In fact, I almost did not pass a recent re-roof inspection with our county because I had an "unsecured" hot tub lid.
All of these city and county regulations make it impossible for vector control/mosquito abatement personnel to access those bodies of water in back yards. Another possible theory to the green pools? How about people too busy working to attend to their own pools, or pay the monthly fees for regular pool maintenance. Or, how about those increased summertime temperatures (global warming?) coupled with an increase in phosphates in the hose water, used to fill the pool over the hot summer?
Effect of post-partum HIV treatment discontinuation
Source: Onen NF, et al. Effect of postpartum HIV treatment discontinuation on long-term maternal outcome. J Int Assoc Physicians AIDS Care. 2008;7:245-251.
Longer term outcomes of HIV-infected women who continue antiretroviral therapy post-partum were compared with that of women who did not continue treatment. A total of 172 pregnancies occurring between 1997-2005 were examined. The median duration of follow-up was 32 weeks. Post-partum discontinuation of antiretroviral therapy occurred in 123 (71.5%) women. A total of 12 opportunistic infections and 2 deaths occurred, a significant number of which were observed in women no longer receiving ART (including 10 OIs and both deaths).
Unfortunately, information on CD4 cell counts and the need for ART based on other factors was not available. (Attempts to download the article were met with a request for $30 to view the article online for one day). Since pregnancy is, to some degree, an immune suppressive state, it is conceivable that the combined effects of pregnancy and HIV status may be additive, and require a more aggressive treatment response during the post-partum period. Without more information, these data suggest that women who discontinue ART post-partum may not do as well as their counterparts who continue treatment. Additional information and study would be helpful in defining recommendations for treatment in HIV-infected woman who have recently delivered.
Thousands of years later — a new kind of leprosy
Source: ProMED-mail post November 24, 2008; www.promedmail.org
Diffuse lepromatous leprosy (DLL) is an especially virulent form of multibacillary disease, occasionally seen in patients from Central and South America and Southeast Asia. Lucio's phenomena is a highly anergic and more severe form of DLL, resulting in extensive skin and subcutaneous involvement, with an abundance of organisms infiltrating tissues. Dermal infarcts occur, occasionally resulting in extensive necrosis, with histopathologic evidence of obliterative vasculitis of dermal and subcutaneous vessels. These extensive skin lesions increase the risk for super-infection and sepsis.
These authors from MD Anderson report on two such cases occurring in 2002 and 2007 at their facility, the first of which was so severe as to prompt transfer to the burn unit. The second occurred in an older Latino from Mexico, who presented with extensive skin lesions on his lower extremities. Within days, he became septic and died. Autopsy confirmed the presence of DLL, with diffuse AFB infiltrating blood vessels.
Having done gene sequencing on other organisms, the authors turned their hand to the organisms responsible for these two cases. Sequences of the 16S ribosomal subunit and five other genes were examined and compared to other mycobacterial cases, including M. leprae. The 16S ribosomal sequences were only 97.9% homologous with M. leprae — a huge difference, considering that gene sequences in other cases of leprosy are essentially identical. The five other genes reportedly showed important differences as well. The strain identified from these two individuals constitutes a new strain of leprosy — called M. lepromatosis.
Analysis of tissue from two other similar cases of DLL occurring in Singapore, yielded this same organism. All four patients died of their disease. While its distribution worldwide has not yet been determined, the discovery of this new mycobacterial organism may explain some of the variation seen in cases of leprosy.
Screening and treatment of TB in immigrants
Source: Cain KP, et al. Tuberculosis among foreign-born persons in the United States. JAMA. 2008;300:405-412.
Slightly more than half of the cases of active TB occurring in the United States between 2001 and 2006 were reported among foreign-born persons. In all, 47,000 cases of TB were reported among foreign-born persons in the United States during this period. Twenty-eight percent of these cases occurred in recent immigrants (< 2 years from entry), although even persons who had lived in the United States for more than 20 years remain at risk for reactivation of their infection.
The highest rates of reactivation TB occurred in individuals from sub-Saharan Africa (> 250 cases per 100,000 persons), somewhat greater than individuals from Central America (> 100,000 cases per 100,000 persons). Increased age at entry to the United States increased the risk of reactivation disease.
Resistant TB was also greater in persons who were foreign-born. INH resistance was observed in persons from Vietnam (20%), Peru (18%), the Philippines (17%), and China (16%). Persons from either Peru or China were at significant risk of multidrug-resistant disease (6%).
For this reason, it is incumbent on primary care physicians to step-up surveillance of latent TB and treatment of LTBI in persons who are foreign-born, even if these patients have lived in the United States for many years. Many of these patients do not recognize the risk that TB poses to themselves, their families and their colleagues at work, and too often discount their skin test as "old news," or as the result of prior BCG vaccination.
Current public health guidelines recommend 9-12 months of treatment for all of these individuals, regardless of age or length of stay in the United States. I recommend a two-step PPD for all non-BCG-vaccinated persons; the sensitivity and specificity is comparable to the gamma-interferon-based (GIB) assays (approximately 96% specific). In persons who have received BCG, or in whom there is some question of previous vaccination, a GIB assay is more specific than PPD (meaning fewer false positives).
I find it is helpful to phrase the risks, when speaking to patients, as follows: the lifetime risk of reactivation disease in someone with a positive skin test or GIB assay is approximately 7% (or 1 in 13). This lifetime risk is biphasic, and greatest during the two years following exposure and with increasing age. This risk roughly increases to 20% (or 1 in 5) if they have an abnormal chest radiograph consistent with old, healed granulomatous disease. Should they require chemotherapy or steroids or other immunosuppressive therapy, the risk increases to approximately 20% in 3-6 months. Chronic disease, such as diabetes and renal failure, also increase the risk of reactivation disease. Now, ask your patients, who would want to take this risk and possibly exposure their children or their colleagues at work to TB?