FEATURE STORY

Latin America Has No Antibodies to Fight Chikungunya Fever

August 14, 2014

The aedes aegypti mosquito, the vector for dengue and chikunguña

Some 6,000 people in the region have been infected by the virus, but experts warn that this number may rise

Chikungunya fever is spreading more rapidly through Latin America and the Caribbean than it takes to learn to spell and pronounce its name correctly.

The virus has already killed 21 people and infected some 6,000 in the region, a relatively small number compared with similar diseases. However, experts are concerned that Latin Americans still have not developed antibodies against the disease given its recent appearance.

In other words: the entire Latin American population is at risk of infection.

Like Ebola, which is now a global problem, chikungunya originated in Africa. In the local Makonde language, the name of the disease means “to double over in pain.” On that continent, the first outbreaks were reported in 2004. The virus has since spread to Oceania, Southeast Asia and parts of Europe.

And now it has arrived in Latin America.

The first cases were detected in late 2013. So far, an estimated 500,000 people have contracted it, mainly in the Caribbean. The virus spreads quickly: it has now reached southern South America with two confirmed cases in Argentina.

That is not surprising given that the vector of the chikungunya virus is Aedes aegypti, the same as dengue fever, a familiar nemesis in the region. Dengue affected more than 2.3 million people  last year alone.

Fernando Lavadenz, a World Bank health expert, explains why cases have increased in Latin America and the Caribbean and what measures governments can adopt to control it.

Question: Why does this disease seem to “travel” more quickly than other viral diseases?

Answer: We are in a century of migrations and frequent travel, and consequently, in a context where disease spreads rapidly. To date, 30 countries in the Americas have been affected – Argentina is the most recent – and the majority of cases are “imported.”

To give you an idea, every year, nine million people travel to the Caribbean Islands, where chikungunya first appeared in the region, from the United States alone. Undoubtedly, some of these people do not take precautions and are bitten by the Aedes aegypti mosquito. When they return to their country in the viremic stage – with the virus in their bloodstream – they become potential transmitters of the disease when bitten by mosquitos that do not have the virus. This propagates the disease. Today there are native cases resulting from that process.

Additionally, this disease did not previously exist in the region, for which reason 100 percent of the Latin American and Caribbean population is susceptible to it. In other worlds, there is no record of antibodies to chikungunya and no natural resistance to the disease. Consequently, infection via mosquito is extremely high. Finally, the fact that Aedes aegypti is the same vector as dengue means that countries with high rates of that disease also will be vulnerable to chikungunya.

Open Quotes

Countries with an effective epidemiological surveillance system in place for dengue are in a better position to confront chikungunya Close Quotes

Q. How can the governments of the region control chikungunya?

A. First, countries should improve their health intelligence, including research, monitoring and an epidemiological surveillance system that enables them to rapidly identify patients with typical chikungunya symptoms.  Cases should be reported and processed. Additionally, lab tests should be performed in suspected cases and the environment should be controlled to prevent an epidemic.

Some countries have already developed this health intelligence. Countries with an effective epidemiological surveillance system in place for Dengue are in a better position to confront chikungunya because they can use the same prevention and control mechanisms for both diseases. Argentina is one such country, whose efforts to combat dengue can serve as a model for the rest of Latin America.

Furthermore, health professionals and decision-makers require training. They must learn about the disease’s clinical characteristics and mortality rate. National guides with specific protocol for identifying and fighting the disease should be distributed. An estimated 50 percent of patients have symptoms; however, in order to identify them it is important to have the same level of information and training.

Q: And how can the population be prepared?

A: Communities should be taught to protect themselves against mosquito bites using simple measures such as mosquito nets and insect repellent. They should wear long sleeves and pants. Moreover, mosquito control efforts should be strengthened: the indiscriminate growth of the mosquito population should be stopped by avoiding storing water in earthenware pots, which are potential breeding grounds. These are the same precautions used to combat dengue. Zones vulnerable to dengue will also be susceptible to chikungunya.

Q. Is there enough information on Chikunguña? Could its symptoms be confused with those of Dengue?

A. The Pan American Health Organization has developed technical guidelines and recommendations which should be distributed to help differentiate dengue from chikungunya. The main difference is that chikungunya produces extreme, long-term joint pain whereas this pain is infrequent or less severe in the case of dengue. But the diseases share many other symptoms, including fever.

If the system and the population are prepared, no one should die from chikungunya or dengue, although the latter has a hemorrhagic -variant which poses a higher risk of death. In both cases, health care services for patients with chronic disease and older persons should be improved.