Concerns over recent human infections of swine Streptococcus in Viet Nam

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Swine Streptococcus (Streptococcus suis) information and discussion

from Wikipedia: (link)

Streptococcus suis is a peanut-shaped, Gram-positive bacterium, and an important pathogen of pigs. Endemic in nearly all countries with an extensive pig industry, S. suis is also a zoonotic disease, capable of transmission to humans from pigs.<sup id="cite_ref-Sriskandan_2006_0-0" class="reference">[1]</sup> Humans can be infected with S. suis when they handle infected pig carcasses or meat, especially with exposed cuts and abrasions on their hands. Human infection can be severe, with meningitis, septicaemia, endocarditis, and deafness as possible outcomes of infection.<sup id="cite_ref-Huang_2005_1-0" class="reference">[2]</sup> Fatal cases of S. suis are uncommon, but not unknown.<sup id="cite_ref-Sriskandan_2006_0-1" class="reference">[1]</sup>
Penicillin is the most common antibiotic used in treatment of S. suis infection; in cases with cardiac involvement (endocarditis), gentamicin should also be given for synergistic effect.
Zoonotic outbreaks

In July 2005, an outbreak of the disease in humans was reported in Sichuan, China, with higher than usual human morbidity and mortality; over 100 cases and more than 20 deaths were initially reported. Prior to this outbreak, less than 200 total human cases had been reported, and mortality was assumed to be less than 10%. Details of this outbreak and a similar earlier outbreak, also in Sichuan province, have recently been published.<sup id="cite_ref-Tang_2006_2-0" class="reference">[3]</sup> A smaller outbreak occurred at the same time in Hong Kong, affecting 11 people.<sup id="cite_ref-3" class="reference">[4]</sup>
A total of 204 human cases were documented during the Sichuan outbreak, with 38 fatalities. The human outbreak coincided with one in the local pig populations. There was no evidence of human-to-human transmission; all of the patients had been in direct contact with pigs. Many of the patients, and almost all of the fatal cases, had typical symptoms of Streptococcal toxic shock syndrome (STSS). To date, STSS has only been documented in patients infected with S. pyogenes, another member of the Streptococcus family but very different from S. suis. However, the bacteria isolates from the human and pig samples were clearly S. suis, and those isolates were able cause typical S. suis disease in piglets.<sup id="cite_ref-Tang_2006_2-1" class="reference">[3]</sup> The genome of S. suis isolates from the outbreak were examined to see whether its DNA sequence could explain why these particular bacteria were able to cause STSS. However, none of the genes that are present in S. pyogenes and thought to cause STSS were detected in the S. suis isolates. Comparison with other S. suis isolates from around the world, including one from an earlier smaller S. suis outbreak in Sichuan province that killed 14 out of 25 reported human cases, revealed that the two Chinese isolates were more similar to each other than to any other strains.
Additional experiments are necessary to determine whether the size and high mortality of the recent outbreak is because the Chinese S. suis version is more virulent than other strains or due to the circumstances under which the Chinese patients got infected and treated. Studies are under way to characterize the bacterial isolates from the outbreak in detail. Physicians around the world should be aware of the possibility of S. suis-associated STSS when they see patients with unexplained sepsis who had been in contact with pigs.
Streptococcus suis has also been identified as the most common cause of meningitis in Vietnam<sup id="cite_ref-4" class="reference">[5]</sup>.
References

1. ^ ^a ^b Sriskandan S, Slater JD (2006). "Invasive Disease and Toxic Shock due to Zoonotic Streptococcus suis: An Emerging Infection in the East?". PLoS Med 3 (5): e187. doi:10.1371/journal.pmed.0030187. PMID [http://medicine.plosjournals.org/perlserv/?request=get-document&doi=10.1371/journal.pmed.0030187 fulltext 16594733 [http://medicine.plosjournals.org/perlserv/?request=get-document&doi=10.1371/journal.pmed.0030187 fulltext]].
2. ^ Huang YT, Teng LJ, Ho SW, Hsueh PR (2005). "Streptococcus suis infection". J Microbiol Immunol Infect 38 (5): 306?13. PMID 16211137.
3. ^ ^a ^b Tang J, et al. (2006). "Streptococcal Toxic Shock Syndrome Caused by Streptococcus suis Serotype 2". PLoS Med 3 (5): e151. doi:10.1371/journal.pmed.0030151. PMID 16584289.
4. ^ "Breaking the taboo". The Hong Kong Standard. October 8, 2005. http://www.thestandard.com.hk/news_...id=2966&sid=4842264&con_type=1&d_str=20051008. Retrieved 29 July 2009.
5. ^ Mai NTH, Hoa NT, Nga TVT, et al. (2008). "Streptococcus suis meningitis in adults in Vietnam". Clin Infect Dis 46 (5): 659?667. doi:10.1086/527385.

And From the Pig Site (link)

Streptoccal Infections
Streptococci are common organisms in all animals. They are broadly but not entirely species specific. The main species in pigs is Streptococcus suis which is widespread in pig populations and probably occurs wherever pig farming is carried out. It is associated with a variety of conditions including meningitis, septicaemia, polyserisitis, arthritis, endocarditis and pneumonia. It has also been isolated from cases of rhinitis and abortion. The pattern and relative importance of the different syndromes vary in different countries. S. suis is sub-divided into at least thirty-four serotypes. They vary in their pathogenicity and the clinical signs they cause, both between and within types. Some types appear to be non-pathogenic and have been isolated mainly from healthy pigs, some are mainly associated with lung lesions, and some have been isolated from other animal species as well as pigs. Some types, mainly 2, can occasionally cause meningitis in people as well as pigs. Fortunately human cases are rare. . . .

Finally, from the Warmwell site (link), an historical review of news articles about streptococcus suis from 2005 and 2006 and the potential for a human epidemic. Selective quotes.

August 2005
Streptococcus suis is a name we may, unfortunately, become familiar with in the coming weeks. In Beijing, in one of the strongest measures yet taken to combat the streptococcus suis disease, authorities have impounded at least 4,000 tonnes of pork from areas affected by the outbreak. Reuters Alertnet
This pig disease has infected about 200 and killed over 30 people in China.
. . .
January 2006
A Hong Kong woman has been infected with a deadly pig-borne disease that last year killed at least 40 people in China, the government said Tuesday. Laboratory tests confirmed the 69-year-old woman was infected with streptococcus suis, the Department of Health said in a statement. It was the first case in the territory this year.
. . .
April 11, 2006
While fears over H5N1 mutating into a form that can affect humans seem to be receding, we read today of research in China that suggests there is potential for a pandemic from a pig disease bacterium that may have genetically changed. The work of lead author Tang Jiaqi of the Research Institute for Medicine of Nanjing Command, China, is published in PLoS Medicine today (11 April).
. . .
April 12, 2006
The emergence of any new zoonotic infectious disease associated with high mortality is of global concern, and there is an urgent need for better characterisation of the S. suis strains involved. Whether the Chinese strain has enhanced virulence per se is at present unclear; the increased mortality seen with the two Chinese outbreaks may simply reflect regional differences in mode of acquisition or in access to treatment.
. . .

While there seems to be some confusions whether Streptococcus suis (a bacterium) or Porcine Reproductive Respiratory Syndrome (PRRS) (a virus) is causing deaths of individuals in Viet Nam (See this thread for links and see this thread for links about disease alerts in Viet Nam), Streptococcus suis is a serious public health concern in its own right and should be carefully monitored for genetic changes that might increase its transmissibility or morbidity in humans.