Intestinal parasites alter immunity in cholera patients

Mar 31, 2009

Cholera patients also infected with parasitic intestinal worms have a significantly reduced immune response to the cholera toxin, according to a report published March 31st in the open-access journal PLoS Neglected Tropical Diseases. Results of the study from a collaborative team led by researchers at Massachusetts General Hospital (MGH) and the International Centre for Diarrhoeal Disease Research, Bangladesh (ICDDR,B) suggest that parasitic infection could reduce immunity to future cholera infection and may compromise the effectiveness of cholera vaccines.

Vibrio cholerae infections cause an estimated 5 million cases of annually worldwide, primarily in impoverished areas with poor sanitation. Intestinal parasites, such as the worms called helminths, are also common in developing areas when cholera is endemic, but there has been little investigation into the impact of infection with both types of pathogen.

For the current study, the research team enrolled about 400 cholera who came to ICDDR,B between 2001 and 2006. After verifying that participants were infected with V. cholerae, the investigators examined stool samples for the presence of intestinal parasites. Blood samples were collected the day after patients enrolled in the study and 7 and 21 days later.

Of 361 patients with confirmed cholera who completed the 21-day follow up, 53 were also infected with at least one intestinal parasite, most frequently helminths. Analysis of participants' blood samples showed that helminth-infected patients had a significantly reduced to the cholera toxin, with the greatest reduction in the IgA antibodies that are secreted in the intestine. The response against a sugar-based molecule that is also important in the immune response was not reduced, implying that the reduced response could relate to the effects of helminth infection on CD4+ helper .

"It's been a puzzle as to why cholera vaccines that initially look so promising in trials in volunteers in Europe and the United States have been much less effective in inducing a strong immune system response in countries where cholera occurs. Our study supports the idea that co-infection with intestinal worms may be part of the explanation for that discrepancy," says Jason Harris, of the MGH Division of Infectious Disease, the study's lead author. "Although we need additional studies to understand the reason for the association between helminths and decreased immune responses to cholera, this study shows that deworming programs could have an added benefit, especially in countries where cholera is present."

More information: Harris JB, Podolsky MJ, Bhuiyan TR, Chowdhury F, Khan AI, et al. (2009) Immunologic Responses to Vibrio cholerae in Patients Co-Infected with Intestinal Parasites in Bangladesh. PLoS Negl Trop Dis 3(3): e403. doi:10.1371/journal.pntd.0000403, dx.plos.org/10.1371/journal.pntd.0000403

Source: Public Library of Science (news : web)

Explore further: Sierra Leone streets deserted as shutdown begins

add to favorites email to friend print save as pdf

Related Stories

Cholera vaccine could protect affected communities

Nov 27, 2007

A vaccine used to protect travelers from cholera, an infection characterized by diarrhea and severe dehydration, could also be used effectively among those living in cholera-prone (endemic) areas, according to a research ...

Tribendimidine shows promise against intestinal worms

Oct 15, 2008

Researchers have reported positive results from a safety and efficacy study pertaining to tribendimidine, a broad-based treatment for intestinal worm infections. The group's results demonstrate the success of the new drug ...

Recommended for you

Sierra Leone streets deserted as shutdown begins

2 hours ago

Sierra Leone's normally chaotic capital resembled a ghost town on Friday as residents were confined to their homes for the start of a three-day lockdown aimed at halting the deadly Ebola epidemic.

Sierra Leone launches controversial Ebola shutdown

4 hours ago

Sierra Leone on Friday launched a controversial three-day shutdown to contain the deadly spread of the Ebola virus, as the UN Security Council declared the deadly outbreak a threat to world peace.

Cooling of dialysis fluids protects against brain damage

17 hours ago

While dialysis can cause blood pressure changes that damage the brain, cooling dialysis fluids can protect against such effects. The findings come from a study appearing in an upcoming issue of the Journal of the American So ...

Two Ebola vaccines to be tested in Switzerland

18 hours ago

Clinical trials of two experimental vaccines against the deadly Ebola virus are due to begin soon in Switzerland, the country's Tropical and Public Health Institute said on Thursday.

User comments : 0