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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.
MRSA at the Zoo
Source: Methicillin-resistant Staphylococcus aureus skin infections from an elephant calf — San Diego, CA, 2008. MMWR Morb Mortal Wkly Rep. 2009;58:194-198.
An increasing number of reports document transmission of MRSA between humans and animals, including people and their pets, horse trainers, and farm personnel. Various MRSA genotypes have been found circulating among farm workers, especially among pig farmers. Reports from the Netherlands documented the emergence of a novel clone of non-typable MRSA since 2003-2004, which has since been found in nearly one-fourth of patients hospitalized with MRSA in that country (MRSA in Pig Farmers. Infectious Disease Alert. 2008;27:119.). MRSA also has been found in pig farmers in Ontario, Canada.
This recent MMWR report details the results of an investigation of a number of cases of MRSA infection stemming from contact with a baby African elephant at a San Diego zoo. The mother elephant had complications at birth (though has since recovered) and was unable to nurse, so the calf, which was born two weeks premature, required extensive care and feeding, as well as a central line for total parenteral nutrition. According to the report, the handlers blew air into the calf's nose to stimulate bottle feeding. About three days after the central line was placed, the calf developed cellulitis at the entry site, followed by recurrent skin pustules, all of which were culture positive for MRSA. The development of MRSA infection in several of the animal providers prompted further investigation. In total, 20 individuals were affected by this outbreak, including two with documented MRSA infection, 15 with suspected infection, and three persons with MRSA colonization, all of whom provided care for the animal. All of the isolates were MRSA USA300 by PFGE. Because the mother elephant was culture-negative for MRSA, it is suspected that one of the handlers was previously colonized with MRSA, resulting in infection in the calf.
This is not the first article to suggest that elephants with respiratory infection may present an increased risk of transmissibility. A case of TB in a circus elephant resulted in a number of exposures among circus personnel and other elephants. Their large trunks, with extensive mucous membranes and dripping nostrils, are optimal for transmitting infection, such as nasal colonization with MRSA.
Sadly, the baby elephant failed to thrive and was euthanized. The autopsy showed enterococcal endocarditis.
Implications of Maraviroc in Other Infections?
Roukens AH, et al (Correspondence). AIDS 2009; 23: 000.
It is well-recognized that the chemokine receptor CCR5 functions as a co-receptor for HIV, while the CCR5-32 gene deletion mutation confers resistance to HIV infection in the homozygous state and is associated with a slower progression of HIV infection when in the presence of single allele. Thus, the newer HIV drug, maraviroc, was designed to act as an antagonist for the CCR5 receptor, effectively mimicking the CCR5 32 mutation and slowing the progression of HIV.
Since the discovery of the CCR5-32 mutation, there has been intense interest in the evolutionary implications of this gene deletion. Some theorize this gene deletion may have conferred an evolutionary advantage, as it appears to have emerged (or diverged) in differing populations around the 15th to 16th centuries, perhaps because of epidemics such as the plague during those years.
Roukens et al postulate that antagonism of the CCR5 receptor in patients receiving maraviroc may have other unintended consequences. Epidemiologic and laboratory data suggest that the CCR5-32 mutation may be associated with increased severity of flavivirus infection, such as tick-borne encephalitis and yellow fever. One report described a patient with severe yellow fever vaccine-associated viscerotropic disease, who was heterozygous for the CCR5-32 mutation. Although yellow fever vaccination of HIV+ persons was previously discouraged in the 1990s, HIV-infected persons with CD4 counts > 200 cells/microliter now can be safely immunized per current ACIP recommendations. The use of maraviroc in some HIV-infected patients may prompt rethinking of these recommendations. Although not yet widely used in developing countries where yellow fever is endemic, it is not known whether the use of maraviroc should be discouraged in those non-immune to yellow fever.
HCV infection also prompts CCR5 chemokine signaling, resulting in gamma interferon production; gene deletion may result in a subtle reduction in that response, the clinical significance of which is not clear. Sub-studies of HIV-infected patients, co-infected with HCV, who are receiving maraviroc, do not appear to have more severe liver impairment or abnormal liver function studies.
Impact of Legalization of Prostitution on Sexual Behavior
Source: Seib C, et al. Commercial sexual practices before and after legislation in Australia. Arch Sex Behav. 2008 Dec 30. [Epub ahead of print]
This fascinating article from the Schools of Nursing and Public Health in Queensland, Australia, delves into the changes in the sex trade that occurred following the legalization of prostitution in Australia in 1992 and 1999. This legislative change allowed for licensed sex workers to operate as sole proprietors or to work for licensed brothels, though a smaller, illegal (largely street) trade still remains.
Two-hundred female sex workers (ages 16-46 years) were recruited for this cross-sectional survey in 1991, and compared to similar data obtained from 247 female sex workers (ages 18-57 years) recruited in 2003. Most of the female subjects were recruited by word of mouth. In addition, 161 male clients (ages 19-72 years) were recruited from legal establishments for comparison with the female responses, including assessment of what services they would prefer to pay for and what they actually received.
During the intervening 12 years, substantial changes in the sex industry in Australia occurred. Seib et al liken the legal sex trade to any other "mature market economy," with integration of the trade into the business community, the tax system, and with provisions for employee health and safety, and employee rights vs. customer rights. Legally employed sex workers receive compulsory training in safe sex and safe sex negotiation, visual screening for STDs, and training in personal protection. The legal brothels employ strict no smoking/no drugs/no alcohol policies and a compulsory condom policy.
Female workers in 1991 were recruited from escort services (52%), the street (16%) or other sole operators (26%), or from illegally run brothels (16%). By 2003, the sample included woman recruited from licensed brothels (41%), legal sole proprietorships (42%), as well as a lesser number who remained illegal (17%), most of whom worked the street. Workers and clients were surveyed regarding their requested and provided services, sex behaviors, use of condoms, incidence of STDs, substance abuse, marital status, and relationship satisfaction. From 1991 to 2003, fewer of the women were Australian by birth (84% vs. 69%, respectively), fewer were single and never married, and there was an increase in the number of women with children (27% vs. 53%, respectively).
Major differences occurring between 1991 and 2003 included an increase in the diversity of services, especially what would be considered more exotic and dangerous activities, as well as a significant increase in the use of condoms and a reduction in unprotected oral sex (including a reduction in oral sex with ejaculation).
Lesbian double acts, cross-dressing, fetish-type activities, and use of sex toys, as well as urination during sex, were significantly increased by 2003, as were bondage, discipline, and submission activities. There was also a trend toward an increase in anal sex and fisting, although more men appeared to request these services than received them. The proportion of sex workers providing the "usual" sexual activities, such as vaginal sex, mutual masturbation, and massage did not significantly change, although there was a slight decline in the proportion who provided only vaginal sex, as well as the number of sex workers who had ever provided oral sex without a condom.
Responses between legal sex workers and clients in 2003 were fairly consistent, indicating that men generally received the services requested, with few exceptions; there did appear to be a greater demand for anal sex, fisting, and urination during sex than available providers.
A significant proportion (70%) of female sex workers reported receiving oral sex from clients in 2003, which Seib et al suggest may be due to a more consistent or assumed personal relationship. By 2003, the number of men having sex with a variety of women had decreased (65% vs. 47%), and the frequency of visits to legal establishments had increased, especially those visiting sole proprietorships.
In contrast, sex activities and provided services did not significantly change for illegal workers between 1991 and 2003. Illegal sex workers were more likely to give unprotected oral sex, as well as anal sex, and least likely to use sex toys or to receive oral sex, suggesting that illegal workers had a more limited ability to negotiate safer sex or specific practices. Interestingly, there was a lower availability of more "dangerous" activities, such as fisting and bondage in the illegal sector. Although this was not specifically addressed by Seib et al, it may be that illegal street workers, with a more tentative hold on their trade, cannot make the investment in equipment, props, and toys that a legal worker, with a stable job and a stable venue, may.