Effectively prevent the spread of cholera

Vaccination to prevent cholera, will help limit the number of deaths when cholera outbreaks, according to new research.

Vaccination against cholera, in a large number of people against the first signs of cholera, can save hundreds or even thousands of lives, according to new analysis from the recent outbreak of cholera in Zimbabwe, the Zanzibar Islands (of Tanzania) and India. Another study showed that immediate vaccination , in Vietnam, was effective, helping to limit the spread of the disease . Both of these studies have been published in the January issue of PLoS Neglected Tropical Diseases.

Although there are doses of vaccines that patients can take, convenient for cholera control, public health officials often do not actively vaccinate cholera during the outbreak period. play. Because health workers often manipulate books, it is to add water to patients with diarrheal diseases to help patients cope with the consequences of dehydration caused by cholera. Besides, often cholera spread quickly to new areas in a short time, before a preventive campaign could take effect. Moreover, the bacterium Vibrio cholerae, which causes cholera, has changed shape in recent years, causing long-term infections and the risk of widespread outbreaks.

Vibrio cholerae bacteria

" Historically, cholera vaccine has been used as a secondary solution ", according to Immunologist, Edward Ryan, working at Harvard University and Massachusetts General Hospital, in Boston, USA , expert on cholera, and who are not involved in new studies. Public health officials have focused on detecting cases of infection, adding water to cholera patients, providing clean water and improving sanitation to prevent the spread of cholera. , Edward Ryan said.

" The complex developments of the pandemic and the data we have obtained from the two studies show that it is time for us to review the role of cholera vaccine in quenching a nest. translated ", Ryan said.

Cholera outbreak broke out in Zimbabwe

In one study, scientists collected information about cholera, over the past 15 years, from the three regions where cholera outbreaks have occurred: Zimbabwe, Zanzibar (Tanzania) and India. Degree.

In Zimbabwe republic, Africa, cholera has killed more than 4,000 people and infected nearly 100,000 people, only between 2008 and 2009. Based on analysis of specialized computers, The researcher found that a campaign to vaccinate half of the population in the Zimbabwe republic, was able to prevent 40% of cases of infection and nearly 1,700 deaths, according to research results by Rita Reyburn. , working at Seoul Institute of Vaccine, Korea, and international colleagues.

Another analysis from seven cholera outbreaks occurred in the Zanzibar and Pemba peninsula, in the Indian Ocean (both islands in Tanzania) during the period between 1997 and 2004. shows that if vaccination is extended to more than half of the population in the Zanzibar and Pemba Islands, it will reduce the case from 4% to 29%, depending on the outbreak.

When applying extended vaccinations to more than half of the population for three outbreaks that broke out in Kolkata (Calcutta, India) between 2003 and 2005, computer analyzes showed, injections. Preventing more than 50% of the population, can help prevent up to 36% of cases.

The analysis suggests that, at best, countries should prepare a stockpile of cholera vaccine , allowing vaccination for more than 50% of the population over a 10-week period. the reaction is more than 10 weeks late, will reduce the effectiveness of vaccine prevention, as well as more deaths.

While the global reserve is full of yellow fever vaccine, there is not enough reserve of cholera vaccine.

However, Vietnam, where cholera has become popular in the past decade, has its own cholera vaccine stockpile . Vietnamese health officials have expanded vaccinations, successfully quenching cholera outbreaks in Hanoi, between 2007 and 2008, a move that seems to have succeeded in preventing epidemics. Describe in any area, the effectiveness of prevention is from 5% to 94% of cases that are likely to be infected, according to a separate report published in PLoS magazine Neglected Tropical Diseases .

According to Dr. Dang Duc Anh, Deputy Director of the National Institute of Hygiene and Epidemiology, in Hanoi and colleagues, identified: 54 people were infected with cholera and 54 others were not infected. People who have not been sick when vaccinated, are less likely to be infected twice than those who have been infected.

Cholera is spread through drinking water, contaminated by feces of infected people. These two studies did not account for the spread of the disease, through population vaccination, reducing fecal contamination of water supplies. And also do not account for " group immunity ", ie how to protect those who have not been vaccinated against the vaccine, while others, around them are vaccinated and not infected, Ryan said. " For these reasons, the effects we are seeing in these two studies, may be lower than the real benefits of vaccination on a global scale that will be implemented in practice, " according to Immunologist, Edward Ryan.