Published Date: 2012-06-21 19:31:17
Subject: PRO/EDR> Cholera, diarrhea & dysentery update 2012 (22): Haiti
Archive Number: 20120621.1173083
CHOLERA, DIARRHEA AND DYSENTERY UPDATE 2012 (22): HAITI
A ProMED-mail post
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International Society for Infectious Diseases
In this update:
 Haiti: recent statistics
 Haiti: O1 and non-O1, non-O139
 Haiti: recent statistics
Date: Fri 15 Jun 2012
Source: New England Cable News (NECN), Associated Press (AP) report [edited]
The Haitian capital, Port-au-Prince, has seen a dramatic drop in the number of cholera cases as the Caribbean nation leaves the annual rainy season, the director of an international aid group said Friday, 15 Jun 2012.
Despite the decline, the Haitian government and health organizations must continue focusing efforts on stemming the outbreak as the height of the hurricane season nears, said Thierry Goffeau, head of mission for Doctors Without Borders in Haiti.
Goffeau said by telephone that authorities should not "go on standby because the numbers are going down" and that "it's important for the UN, the international donors to increase their support."
Goffeau said his humanitarian health group saw the number of weekly cholera cases in Port-au-Prince jump from 708 in late April 2012 to 1354 in late May 2012. Last week, the organization treated 528 people in the capital.
This drop was mirrored at a Doctors Without Border treatment center in Port-au-Prince's densely populated neighborhood of Drouillard. A 75-bed facility was filled for 4 weeks until the end of May 2012, but now has about 10 patients.
Despite the decline in cases, cholera continues to sicken people in Haiti. Health officials say it has killed more than 7200 people and sickened another 555 000 in the country.
 Haiti: O1 and non-O1, non-O139
Date: Mon 18 Jun 2012
Source: Los Angeles Times [edited]
American researchers have linked a 2nd strain of cholera to the epidemic that decimated the Haitian population in 2010-11. Previous studies have suggested that the epidemic was caused by bacteria inadvertently introduced by Nepalese soldiers who came to assist in recovery from a massive earthquake. The new strain appears to be local in origin, but its role in the epidemic is not clear because this strain does not normally produce epidemics.
Haiti suffered a devastating magnitude 7 earthquake on 12 Jan 2010, followed by about 52 aftershocks with a magnitude of 4.5 or higher. Estimates indicate that more than 250 000 died immediately, about 300 000 were injured and 1 million were rendered homeless. Cholera cases began to appear in October 2010 and the spread of the disease was exacerbated by Hurricane Tomas, which skirted the island, but produced torrential rains and severe flooding. To date, cholera has killed an estimated 7500 Haitians and sickened half a million.
Early studies by the CDC and other researchers showed that the primary cause of the epidemic was a bacterium known as _Vibrio cholerae_ O1, the classical epidemic strain. Many researchers speculated that the strain was brought to the island by Nepalese soldiers sent to provide relief, but none of the soldiers is known to have suffered cholera before arriving in Haiti.
A team headed by geneticists Claire M Fraser-Liggett and Rita R Colwell of the University of Maryland in College Park collected fecal samples from 81 cholera victims in 18 Haitian towns in November 2010, early in the outbreak. The team then sequenced the cholera bacterium in 76 of the samples. They reported Mon 18 Jun 2012, in the Proceedings of the National Academy of Sciences that 47 of the samples contained the _V. cholerae_ O1 strain that is thought to be the cause of the epidemic. But 29 of them contained only strains known as _V. cholerae_ non-O1/0139.
The latter strains of the bacterium are found routinely in waterways and estuaries in the Western Hemisphere. They produce diarrhea but are not thought to be capable of causing an epidemic. But because so many of the patients carried the supposedly non-epidemic strain, the researchers concluded, it must be able to produce an epidemic either alone or in concert with _V. cholerae_ O1.
[Byline: Thomas H Maugh II]
[The publication, released as an "early edition" paper, Hasan NA, Choi SY, Eppinger M, et al: Genomic diversity of 2010 Haitian cholera outbreak strains. PNAS 2012: 1207359109v1-201207359; http://www.pnas.org/cgi/doi/10.1073/pnas.1207359109, reports on cultures of individuals from 18 towns across Haiti in November 2010, early in the epidemic. It is interesting that, only now, 21 percent of isolates were non-O1, non-O139 strains, which are generally thought to not cause large outbreaks. Of note, the non-O1, non-O139 strains found harbored a genomic backbone similar to some _V. cholerae_ O1 strains similar to O1 strains isolated from Brazil in 1980 and 1991.
_Vibrio cholerae_ Non-O1 Non-O139, from the FDA's Bad Bug Book, 2nd ed. (http://www.fda.gov/downloads/Food/FoodSafety/FoodborneIllness/FoodborneIllnessFoodbornePathogensNaturalToxins/BadBugBook/UCM297627.pdf)
This Gram negative, curve-shaped bacterium is naturally occurring in brackish (that is, somewhat salty) water, but survives and occurs in aquatic environments ranging from freshwater to open ocean. Non-O1 non-O139 _V. cholerae_ typically do not produce cholera toxin (CT), and little is known about how these organisms cause disease. The only serogroups of _V. cholerae_ currently recognized as causing cholera are O1 and O139; however, cholera-like symptoms have been infrequently reported in the United States from CT-producing strains from serogroups O141 and O75.
(Note: this organism should not be confused with other _Vibrio_ serogroups or species addressed in other chapters of this book: _Vibrio cholerae_ O1 and O139, which does cause cholera; _V. parahaemolyticus_; and _V. vulnificus_.)
_V. cholerae_ non-O1 non-O139 are more hardy than most of the other pathogenic _Vibrio_ spp., and have the ability to survive in freshwater and in water composed of up to about 3 percent salt. However, these organisms are very susceptible to cold temperatures, including freezing and acid environments. Additionally, cooking food thoroughly kills _V. cholerae_ non-O1 non-O139. _V. cholerae_ non-O1 non-O139 are not encapsulated, and are susceptible to common disinfectants, such as ethanol and bleach.
Non-O1 non-O139 _V. cholerae_ causes gastroenteritis, but not cholera. Occasionally, it causes septicemic infections among people with predisposing conditions. Those conditions include chronic liver disease (cirrhosis, hepatitis, liver transplantation, and cancer of the liver), elevated serum iron levels (hemochromatosis), compromised immune system (for example, chemotherapy, steroid use and other immunosuppressive medications, AIDS), other chronic illnesses (diabetes, renal disease, intestinal disease, and insufficient gastric acid). People with these conditions, especially, should eat seafood only if it has been properly cooked.
- Mortality: the fatality rate is about 5 percent, generally among people with the predisposing conditions listed above.
- Infective dose: it is suspected that large numbers (more than 1 million) of the organism must be ingested to cause illness.
- Onset: symptoms usually appear within 1 to 3 days of ingestion.
- Illness/complications: diarrhea resulting from ingestion of this organism is generally self-limiting. However, septicemia infections can result, and there is approximately a 5 percent fatality rate associated with non-O1 non-O139 _V. cholerae_, generally in people having predisposing conditions similar to those for _V. vulnificus_ infection.
- Symptoms: diarrhea, abdominal cramps, and fever are the predominant symptoms associated with this illness, with vomiting and nausea occurring in approximately 25 percent of infected people. Approximately 25 percent of infected people have blood and mucus in their stool.
- Duration: symptoms usually resolve within 7 days.
- route of entry: oral. (Occasionally, infections with this organism that are not foodborne occur in wounds and ears.)
- Pathway: very little is known about how non-CT producing strains of _V. cholerae_ cause disease. These strains generally produce other types of enterotoxins, such as RTX (repeats in toxin); however, none have been shown to be absolutely necessary for infection.
The CDC estimates that 17 564 cases of foodborne illness from these _Vibrio_ species occur annually in the USA.
Sporadic cases generally occur along the coasts of the USA and are associated with consumption of raw, improperly cooked, or cross-contaminated seafood during the warmer months.
Diagnosis of a _V. cholerae_ infection is made by culturing the organism from patients' diarrheic stool or from the blood of patients with septicemia.
6. Target populations
Anyone who eats raw shellfish is susceptible to diarrhea caused by this organism. As noted above, cirrhotic or immunocompromised people may develop severe complications, such as septicemia.
7. Food analysis
FDA's Bacteriological Analytical Manual (BAM) describes the methods most commonly used to isolate this organism from foods. Pathogenic and non-pathogenic forms of the organisms do exist; therefore, testing food isolates for the virulence determinants is recommended. The BAM recommends a PCR method for the detection of the gene responsible for CT production.
8. Examples of outbreaks
This organism generally is associated with sporadic illnesses and rarely causes outbreaks.
- CDC disease listing - General information about _V. cholerae_.
- National Center for Biotechnology Information Taxonomy. Information about the historical classification of _V. cholerae_, as well as current genetic sequence information.
FAO/WHO: Risk Assessment of Choleragenic _Vibrio cholerae_ O1 and O139 in Warm-Water Shrimp in International Trade: Interpretative Summary and Technical Report, World Health Organization/Food and Agriculture Organization of the United Nations, Geneva, Switzerland, 2005 (http://www.who.int/foodsafety/publications/micro/mra9.pdf).
- CDC: 2008. Summary of human _Vibrio cases_ reported to CDC, 2007 (http://www.cdc.gov/nationalsurveillance/PDFs/CSTEVibrio2007.pdf).
- Crump JA, Bopp CA, Greene KD: Toxigenic _Vibrio cholerae_ serogroup O141-associated cholera-like diarrhea and bloodstream infection in the United States. J Infect Dis 2003; 187(5): 866-8 (http://jid.oxfordjournals.org/content/187/5/866.full).
- Tobin-D'Angelo M, Smith AR, Bulens SN: Severe diarrhea caused by cholera toxin-producing _Vibrio cholerae_ serogroup O75 infections acquired in the southeastern United States. Clin Infect Dis 2008; 47(8): 1035-40 (http://cid.oxfordjournals.org/content/47/8/1035.long).
- Vezzulli L, Guzman CA, Colwell RR, Pruzzo C: Dual role colonization factors connecting _Vibrio cholerae's_ lifestyles in human and aquatic environments open new perspectives for combating infectious diseases. Curr Opin Biotechnol 2008; 19(3): 254-9 (abstract available at http://www.ncbi.nlm.nih.gov/pubmed/18501582).
- West BC, Silberman R, Otterson WN: 1998. Acalculous cholecystitis and septicemia caused by non-O1 _Vibrio cholerae_: first reported case and review of biliary infections with _Vibrio cholerae_. Diagn Microbiol Infect Dis 1998; 30(3): 187-91 (abstract available at http://www.ncbi.nlm.nih.gov/pubmed/9572025). - Mod.LL
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