FW: PRO/AH/EDR> Bovine tuberculosis, human - USA: (NV) nosocomial spread, fatal

[Maffei, Joanne]

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BOVINE TUBERCULOSIS, HUMAN - USA: (NEVADA) NOSOCOMIAL SPREAD, FATAL
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Date: Tue 8 Oct 2013
Source: Boston Herald, Associated Press (AP) report [edited] <http://hosted.ap.org/dynamic/stories/U/US_TUBERCULOSIS_EXPOSURE_NEONATAL_UNIT?SITE=MABOH&SECTION=HOME&TEMPLATE=DEFAULT&CTIME=2013-10-08-19-49-49>


Health officials urged tuberculosis [TB] testing for hundreds of babies, family members, and staff who were at a Las Vegas neonatal intensive care unit this past summer [2013], saying they want to take extra precautions after the death of a mother and her twin babies and the infection of more than 26 people.

Authorities with the Southern Nevada Health District said Tuesday [8 Oct 2013] that they're working to contact parents of about 140 babies who were at Summerlin Hospital Medical Center's NICU unit between mid-May and mid-August [2013], and have set up a temporary clinic to test them.

Tests of hospital staff and friends and family of the mother have revealed 26 TB infections, although most of those cases are latent -- meaning patients don't show symptoms and aren't contagious. All 26 are being treated, according to health district spokeswoman Stephanie Bethel.

It's unlikely that the babies who may have been exposed will come down with the disease, according to Dr Joe Iser, the health district's chief medical officer, but officials want to do widespread testing "through an abundance of caution." "It's safer to expand the investigation," Iser said.

Health officials think the woman contracted TB through an unpasteurized dairy product from Latin America, Iser said. The 25-year-old mother then gave birth to extremely premature babies in the Las Vegas area in early May [2013]. One 3-week-old baby, died 1 Jun 2013 of respiratory failure and extreme prematurity, according to the Clark County coroner. She was never tested for TB.

The mother, who had been sick before and after the birth, was eventually admitted to a Las Vegas hospital, and later transferred to a Southern California hospital "for a higher level of care," according to a 22 Aug 2013 report from the health district. The mother died in California and her name was unavailable. An autopsy showed she had tuberculosis meningitis.

The 2nd baby was tested for TB and treated, but she succumbed to the disease at Summerlin Hospital on 1 Aug 2013. The delayed diagnosis may have come because the disease is relatively rare in the US.

"TB can be very subtle, particularly as many doctors have not had much experience with TB these days," said Dr William Schaffner, professor of preventive medicine and infectious diseases at Vanderbilt University School of Medicine.

Families who had babies in the NICU were first informed of the investigation in August [2013], but it wasn't until this week that the health district has urged them to get tested. Before that, health officials tested more than 200 hospital staff members and 69 close family and friends.

"We did a full contact investigation and that helped us to determine her movements during the time she was not hospitalized but likely infectious, and we've followed up with all the contacts we know," Iser said.

Officials from the Centers for Disease Control and Prevention assisted with the probe up until last week, Bethel said. It wasn't immediately clear whether their investigation has been affected by the government shutdown.

TB can be fatal if not properly treated. The CDC counted 569 TB deaths in the US in 2010, the most recent year for which data is available.
The illness is spread through the air when a sick person coughs, sneezes, or speaks. Symptoms include coughing, chest pain, fever, and fatigue.

Schaffner said dairy cattle can sometimes carry the disease and then pass it along through unpasteurized milk, but he contends that's extremely rare, especially in the US. Virtually all cases are transferred from person to person, he said, and TB occurs far more often in people who were born overseas. The number of US TB cases has been on a steady decline since a resurgence in 1992, and in 2012 reached the lowest level since national reporting began in 1953.

[Byline: Michelle Rindels]

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[The news report above describes a nosocomial tuberculosis (TB) outbreak due to exposure to a pregnant patient with unsuspected TB who subsequently died of TB meningitis. One of her "extremely premature"
twins died before the diagnosis of TB was considered; the other twin died as a result of TB.

Diagnosing TB in pregnancy can be difficult because of the vague, non-specific nature of the symptoms. Weight gain, shortness of breath on exertion, and easy fatigue seen normally during pregnancy may mask the associated weight loss, and other symptoms characteristic of TB.
Also, physicians may be unnecessarily reluctant to order a medically indicated chest x-ray for fear of harming the fetus. However, untreated tuberculosis (TB) disease represents a greater hazard to a pregnant woman and her fetus (<http://www.cdc.gov/tb/publications/factsheets/specpop/pregnancy.htm>).
Infants born to women with untreated TB may have lower birth weight than those born to women without TB and in rare circumstances the infant may be born with TB, if the mother has miliary TB, TB of the placenta or uterus, or has advanced HIV (<http://www.cdc.gov/tb/publications/factsheets/specpop/pregnancy.htm>).
Congenital TB has morbidity and mortality approaching 50 percent (<http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2813636/>).

The US CDC recommends treatment of pregnant women should be initiated whenever the probability of TB is moderate to high. Although the drugs used in the initial treatment regimen for TB cross the placenta, they do not appear to have harmful effects on the fetus, and HIV-infected pregnant women who are suspected of having TB disease should be treated without delay (<http://www.cdc.gov/tb/publications/factsheets/specpop/pregnancy.htm>).

Pregnancy has not been found to influence the pathogenesis of TB or the likelihood of progression from latent to active disease, nor has it been shown to affect the response to treatment. Any increase in the proportion of pregnant patients with tuberculosis in developed countries has been attributed to an increase in foreign-born women of childbearing age from countries with high rates of TB or to co-infection with HIV (<http://thorax.bmj.com/content/56/6/494.full>).
The percentage of TB cases in the US accounted for by foreign-born persons increased from 26 percent in 1990 to 60 percent in 2010 and among foreign-born persons with TB, 37 percent were Hispanic or Latino (<http://www.cdc.gov/tb/publications/factsheets/specpop/pregnancy.htm>).
However, we are not told in the news report above if the mother was of Hispanic ethnicity, either foreign-born or US-born, although we are told she "contracted tuberculosis through an unpasteurized dairy product from Latin America", which is frequently favored by the Hispanic community.

Because the news report above says that health officials think the woman contracted tuberculosis through an unpasteurized dairy product from Latin America, presumably they are referring to tuberculosis due to _Mycobacterium bovis_. In the U., TB due to _M. bovis_ continues to be reported, primarily in immigrants, who acquired the infection in their countries of origin where _M. bovis_ infection remains endemic, or in persons of Hispanic ethnicity as a consequence of ingesting dairy foods made from unpasteurized milk of _M. bovis_-infected cows and smuggled across the Mexico-US border (see Levison ME.
_Mycobacterium bovis_: An Underappreciated Pathogen. Curr Infect Dis Rep 2008, 10: 444-6).

_M. bovis_ can be transmitted from infected animals to humans by either ingestion of unpasteurized milk or milk products, such as cheese, or by inhalation of infectious aerosols from infected animals.
Although rare, person-to-person transmission of _M. bovis_ can also occur. Following ingestion of _M. bovis_-contaminated food, _M. bovis_ most commonly localizes in cervical lymph nodes (scrofula) or the gastrointestinal tract and related lymph nodes with subsequent hematogenous dissemination to the lungs and other organs. These forms of _M. bovis_ infection occur commonly in children and were common in developed countries during the pre-pasteurization era. Following inhalation of infectious aerosols of _M. bovis_, primary pulmonary _M.
bovis_ infection develops with subsequent hematogenous dissemination to the lungs and other organs. Reactivation of latent _M. bovis_ pulmonary infection can occur in later life and can clinically resemble disease due to _Mycobacterium tuberculosis_.

The current risk posed by _M. bovis_ to human health in most developed countries is considered negligible because of the success of bovine tuberculosis eradication programs that began early in the last century. These programs involved mandatory pasteurization of urban milk supplies, meat inspection in slaughterhouses, and compulsory tuberculin test-and-slaughter programs. Nevertheless, bovine tuberculosis is still periodically reported in the Unites States and in other developed countries (see ProMED-mail posts: Tuberculosis, bovine - USA (05): (CA) 20080710.2100; Tuberculosis, bovine - USA (OK) 20070501.1420; and Tuberculosis, bovine - USA (04): (MN) status downgrade 20080408.1296).

Human _M. bovis_ tuberculosis still occurs in many developing countries, where bovine tuberculosis remains endemic, and may be under-appreciated in much of the Unites States because of the limited use of complex and expensive diagnostic laboratory testing. The same is also likely true in much of the developing world, where bacteriologic diagnostic testing is generally limited to acid-fast stained sputum smear examination.

Differentiation of infection due to _M. bovis_ from that due to _M.
tuberculosis_ requires special microbiologic laboratory tests that may not be done routinely. Rapid identification in clinical specimens uses a broth-based culture system combined with amplification assays that identify ribosomal RNA common to all members of what is called "Mycobacterium tuberculosis complex" (MTC), which has commonly replaced in many laboratories the more time-consuming tests of colonial and phenotypic differential characteristics. MTC includes _M.
tuberculosis_, the usual cause of human tuberculosis, as well as _M.
bovis_, BCG, _M. africanum_, _M. microti_, _M. caprae_, and _M.
canettii_. BCG is the attenuated bacillus Calmette-Guerin vaccine strain derived from a virulent _M. bovis_ strain that has been used as a vaccine against tuberculosis and increasingly as cancer immunotherapy. _M. microti_ has been reported to infect small rodents like voles and more recently also humans. _M. canettii_ and _M.
africanum_ both cause human tuberculosis, mainly in Africa. If further diagnostic testing is not done, _M. bovis_ may erroneously be presumed to be _M. tuberculosis_.

_M. bovis_ is inherently resistant to pyrazinamide (PZA), a drug that is an essential component of the standard multidrug short-course regimen to treat human tuberculosis due to drug-susceptible _M.
tuberculosis_. Differentiation of _M. bovis_ from _M. tuberculosis_ is therefore important clinically as well as epidemiologically. To distinguish _M. bovis_ from _M. tuberculosis_, spoligotyping (spacer oligonucleotide typing), which is a polymerase chain reaction-based amplification of a region of the mycobacterial genome, or growth in selective media and specific biochemical reactions are done. - Mod.ML

A HealthMap/ProMED-mail map can be accessed at:
<http://healthmap.org/r/6nVQ>.]

[see also:
Bovine tuberculosis, human - Jordan: incidence, comment, RFI
20130822.1892434
Bovine tuberculosis, human - UK: (England) 20130809.1871322 Bovine tuberculosis, human - UK (02): (England) ex alpaca
20120510.1128707
2012
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Bovine tuberculosis, human - UK: (England) ex alpaca 20120427.1116358
2009
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Bovine tuberculosis, human - UK: (England) 20090808.2815
2008
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Bovine tuberculosis, human, canine - UK: (England) (02) 20080927.3054 Bovine tuberculosis, human, canine - UK: (England) 20080903.2751
2006
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Bovine tuberculosis, human - UK (England) (02) 20061015.2967 Bovine tuberculosis, human - UK (England) 20061009.2896
2004
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Bovine tuberculosis, human - UK (Gloucestershire) (02) 20040716.1930 Bovine tuberculosis, human - UK (Gloucestershire) 20040714.1890] .................................................ml/mj/lm
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