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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; is Associate Editor for Infectious Disease Alert.
An old disease in new immigrants
Coccidioidal infections are always unique the travel history often provides the right clue for the practitioner but first you have to think to ask the right question. My practice has recently seen three Asian immigrants hospitalized with what proved to be acute coccioidomycosis; two of whom had focal pulmonary disease (one with cavities and erythema nodosum) and the third with evidence of dissemination to mediastinal nodes and skin. All three were suspected of having pulmonary tuberculosis until pathology and fungal cultures surprisingly revealed coccidioidomycosis. The first two patients were Asian Indian and the third was Chinese. All three worked in high tech in Silicon Valley, were young (28-40 years of age), were in good health, and had recent, albeit brief, exposure to an endemic area. Two of the patients had traveled down Highway 5 from the Bay Area to Las Vegas for holiday, stopping for gas and food along the way. The third, who was Chinese, had traveled to Phoenix for business for 3 days, and had lunch on the outskirts of the city at an outdoor Mexican restaurant.
These cases are reflective of some of the people acquiring coccidioidal infection around the United States young, healthy Asian or Latin American immigrants who happen to be exposed while vacationing or working in higher risk areas of California and Arizona. None of my patients had ever heard of cocci before.
Increases in coccidioidomycosis are occurring in both California and Arizona (approximately 60% of cases in the United States are reported from Arizona).1 From 2000 to 2006, California cases increased from 816 to 2,981. The estimated average annual incidence in California is highest among 40- to 49-year-olds, while hospitalizations are highest among persons aged 60-79 (5.8 hospitalizations per 100,000). Two-thirds of cases (65%) were reported in males. Hospitalizations were highest among non-Hispanic blacks (7.5 per 100,000), followed by Hispanics (3.6 per 100,000), non-Hispanic whites (3.5 per 100,000), and Asians/Pacific Islanders (1.9 per 100,000). From 2000 to 2007, 752 (8.7%) of those 8,657 persons in California requiring hospitalization died. About three-fourths of California cases are acquired in the San Joaquin Valley area, where C. immitis is endemic, with the hot spot being Kern County.
The reason for this apparent increase is not well understood. Mandatory reporting requirements for coccidioidomycosis in California have not changed. Climatic changes and increases in rainfall may impact disease incidence (so this coming year should see an increase in cases in California with the bonanza of winter rain). Increasing numbers of non-immune immigrants from Latin America or Asia and elderly persons who travel for business or pleasure may provide an explanation. My theory is that the booming housing industry in the 2000s and expansion of urban residential areas in both Arizona and California probably played a significant role. Interestingly, based on preliminary data for 2008-2009, cases in Arizona and California may have modestly decreased in 2008. Perhaps the downturn in the housing economy and negative impact on new construction in endemic areas, as well as a decrease in business and vacation travel, had a positive effect on total numbers of coccioidal infections.
Another flavivirus with a non-mosquito vector?
Source: Foy BD, Kobylinski KC, Chilson Foy JL, et al. Probable non-vector-borne transmission of Zika Virus, Colorado, USA. Emerg Infect Dis 2011;17:880-882.
Last month's installment of Updates highlighted the appearance of a new flavivirus called BYD, which has devastated duck egg production and caused duck illness and death in parts of China. While mosquitoes are the presumed vector for this infection, the mode of transmission has not been identified. Increasing evidence suggests that other flaviviruses, for example, West Nile virus, can be transmitted among crows from cloacal shedding and close contact and may not require a mosquito vector. Read on...
Zika virus (ZIKV) is another flavivirus that has been detected in monkeys, humans, and mosquitos, and has resulted in human illness in Africa and Southeast Asia. A major outbreak of ZIKV infection occurred on Yap island in the Pacific in 2007, resulting in infection among 70% of the population. The presumed vector once again is mosquitoes.
The current article by Foy and colleagues describes how two young researchers (ages 27 and 36), working in Senegal, acquired ZIKV infection. The odd twist to the story is that one of them, after returning to the United States, may have transmitted the infection to his wife during sex. Both men left Bandafassi, Senegal, and returned home to Colorado at about the same time. Within 9-12 days of leaving Senegal, both men developed fatigue, headache, and then maculopapular rash on the torso, and swollen ankles and wrists. Oral aphthi occurred. One man developed symptoms of prostatitis and hematospermia. On about the fifth day of his illness, his wife developed similar complaints, including fatigue, severe, disabling headache, photophobia, and muscle pain followed by the appearance of a maculopapular rash on the torso and oral aphthi.
Hemagglutination inhibition antibody titers and virus neutralizing titers in the two men were markedly elevated to both Yellow fever virus (YFV) and ZIKV (both had been vaccinated for YFV), which increased between acute and convalescent specimens. Similar increased titers to ZIKV, but not YFV, were observed in the wife but only in the convalescent specimens, confirming her acute infection with ZIKV alone. These data support the likely transmission of ZIKV from husband to wife, most likely through sexual contact. The epidemiology of these infections may be more complicated than previously understood.
Culture yield in vertebral osteomyelitis
Source: Marschall J, Bhavan KP, Olsen MA, et al. The impact of prebiopsy antibiotics on pathogen recovery in hematogenous vertebral osteomyelitis. Clin Infect Dis 2011;52: 867-872.
Concerns have been raised that delays in obtaining an aspirate for culture, while patients with vertebral osteomyelitis are receiving empirical antimicrobial therapy, may increase the risk of negative culture results. These authors examined the effect of pre-antibiotic exposure on culture results in patients with hematogenously seeded vertebral osteomyelitis. Data for 150 patients hospitalized at a tertiary care hospital with vertebral osteomyelitis were examined retrospectively. Ninety-two of these patients underwent either a needle biopsy (65%) or an open biopsy (35%). Patients were more likely to undergo biopsy if they had focal neurologic deficits (weakness or sensory deficits) or negative blood culture results.
No affect of antibiotic exposure was observed on the culture yield. Cultures yielded a pathogen in 61 of 92 patients (66%), including 91% of those with an open procedure and 53% of those who had undergone needle biopsy. Biopsies were performed within a median of 3 days from admission (range, 0-69 days). Sixty patients had received antibiotics within the 2 weeks prior to their procedure for a median duration of 4 days (range, 1-37 days).
Cultures yielded a single pathogen in 41 of 43 patients, including MSSA (18.5%), MRSA (16.3%) coagulase negative Staphylococcus spp. (9.8%), Streptococcus spp. (7.6%), and Gram-negative bacteria (10.9%). Two patients had polymicrobial infection, with MSSA, Gram-negative rods and/or coagulase-negative Staphylococcus. No yeast or fungi were isolated in culture. For those patients with positive culture results, 90% in the open biopsy group and 87% of those in the needle biopsy group were receiving empirical antibacterials to which their isolate was sensitive.
Minor delays in securing a tissue sample for culture do not appear to affect culture results, despite receipt of antibiotics, but these data should not be used as a pretext for deferring or delaying an appropriate procedure. Not stated here was that many such patients, while waiting for their procedure and culture results, likely receive empirical and much broader spectrum antimicrobials for many more days than may be required. In addition, given the risk of community-acquired MRSA infection, or even non-bacterial pathogens such as yeast, empirical antibacterial therapy may not always provide adequate coverage. Efforts should therefore be made to expeditiously obtain culture results whenever possible.