Saturday, June 19, 2010

Alliance Works for Improved Influenza Surveillance in Africa

Flu seasonal in temperate regions, but infects people all year in tropics

By Cheryl L Pellerin

Washington - As the World Health Organization (WHO) announced that more than 214 countries have confirmed cases of H1N1 pandemic influenza and at least 18,156 people have died, representatives from 33 African nations met for the first time in Morocco to discuss the impact of flu on that continent.

The meeting, held in Marrakech June 3-4 and organized by the United Nations, included U.N. technical partners such as the U.S. Centers for Disease Control and Prevention, the U.S. National Institutes of Health and its Fogarty International Center, the German Technical Cooperation enterprise GDZ, Fondation Mérieux, the Institut Pasteur International Network and the Programme for Appropriate Technology in Health.

It is important to study flu in the mostly tropical setting of Africa because flu is a different disease in the tropics than it is in Earth's temperate regions. In temperate regions like Europe and the United States, flu is a seasonal illness that circulates during the cold months.

In the tropics, according to a 2007 study by Peter Palese of Mount Sinai Medical School in New York and colleagues, flu circulates in people year round with possible increases during rainy seasons. Researchers don't know why flu is seasonal in temperate zones and circulates all year in the tropics.

"The influenza pandemic in Africa has a very different pattern than in the rest of the world," Dr. Sylvie Briand, head of the WHO Global Influenza Programme, told America.gov. "For example, [H1N1] reached western Africa very late in the course of the pandemic, only in the beginning of 2010. Depending on the country, the burden seems to vary a lot, so we thought that it was a good time to come together and see [how flu behaves] on the African continent and what can be done about it."

MONITORING INFLUENZA

Flu viruses are important disease-causing microbes, and flu-related respiratory tract infections like pneumonia are a major cause of death in Africa, particularly among children.

As of June 6, according to WHO, in sub-Saharan Africa, pandemic flu continued to circulate at low levels in parts of West Africa, especially in Ghana. During the most recent reporting week, 13 percent of all respiratory samples tested positive for H1N1 in Ghana. Small numbers of seasonal H3N2 viruses have been detected in Kenya and Tanzania since late May.

As the pandemic progressed around the world after it began in April 2009, WHO routinely gathered information from developed nations about flu and other respiratory illnesses. Such information was harder to come by from many developing countries, which often do not have the resources or capacity to monitor infectious diseases.

"Industrialized countries have what we call sentinel systems, which means that you take some geographical sites of general [health] practitioners whose patients represent a certain portion of the population," Briand said. "These sentinel sites report on influenzalike illness and they are asked to take samples of, for example, one of every 10 patients in a kind of strategy to [monitor] circulating viruses."

The outpatient influenzalike illness surveillance is usually coupled with severe respiratory illness surveillance in hospitals, she added, to find out how many of the influenzalike illnesses are severe.

In developing countries, where only large cities have laboratories that can identify the flulike illnesses, "we are trying to develop new strategies, like in Madagascar where they do reporting by mobile phone," Briand said. "They test a limited number of patients, but they have more exhaustive reporting of influenzalike illness, for example. And they couple the surveillance with rapid tests."

Rapid tests are not as accurate as laboratory testing, but such tests are used only for surveillance and not to determine if someone needs treatment.

"Flu symptoms are not specific so it can be confounded with many other respiratory diseases," she said. "Many influenza cases only have fever. In tropical countries there are so many sources of fever - you have dengue, malaria and a number of other infectious diseases whose first symptom is fever."

In tropical countries, it is hard to know if someone has flu if there is no laboratory to confirm the diagnosis.

AFRICA FLU ALLIANCE

In Marrakech, senior officials from African ministries of health and representatives of health partners and international agencies discussed strategies and defined priorities like what information is needed for surveillance and how to collect the information.

"We heard that the pandemic situation led countries to gather much more information than they do usually on respiratory disease, so reviewing what has happened in the past year may give us a better understanding of influenza in Africa," Briand said.

The informal alliance is seeking partners and ultimately intends to establish an Internet-based platform where African countries and others can share information and benefit from each other's experience.

"First, we will publish a road map that identifies priorities and we will ask partners what they plan to do in each area of work. Maybe next year we will have another meeting to see the progress," Briand said. "The main objective is really to create a platform for discussion among different stakeholders and to enhance synergies."

By the Bureau of International Information Programs, U.S. Department of State