Roughly 50% of people living in the Western Hemisphere are at risk of one or more diseases carried by mosquitoes, ticks, flies and other vectors, including West Nile virus, dengue, malaria and most recently chikungunya. In a "call to action" for World Health Day 2014, top health experts from North and South America and the Caribbean urged greater efforts by governments, communities and individuals to control the spread of these and other vector-borne diseases.
"Our region has achieved many successes in controlling vector-borne diseases," said the Director of the Pan American Health Organization/World Health Organization (PAHO/WHO), Carissa F. Etienne. "However, this success is being threatened by the expansion of mosquitoes and other vectors into new habitats and by the emergence of insecticide and drug resistance. PAHO and its partners are today calling for stepped-up action in the fight against vector-borne diseases in the Americas."
"We as a world are in some ways more vulnerable than ever," said Tom Frieden, Director of the Centers for Disease Control and Prevention (CDC), "and that means that we as a world need to collaborate more effectively than ever so we can build the capacity to find new diseases, outbreaks and threats wherever they emerge promptly, and respond effectively."
In the Americas, the vector-borne diseases with a major public health impact include malaria, dengue, Chagas disease, schistosomiasis, West Nile virus and Lyme disease (in North America). Some of these diseases have been present in the region for a long time, while others are recent arrivals.
The most recent vector-borne disease to establish itself in the Americas is chikungunya, a mosquito-borne viral disease that first appeared in Tanzania in the 1950s. In December 2013, two cases of locally acquired chikungunya were reported in the Caribbean island of Saint Maarten/Sint Martin. By the end of March 2014, more than 3,000 cases had been confirmed in 10 Caribbean countries.
"Chikungunya does not often result in death, but the joint pains and stiffness may last for months and even years," noted Minister of Health of Jamaica Fenton Ferguson, adding that governments and communities should focus prevention and control efforts on reducing the density of mosquito populations.
The Americas region has recently seen major successes in fighting vector-borne diseases. Cases of malaria, for example, declined 60% and malaria deaths declined 72% between 2000 and 2012. Seven countries of the Americas are now in the pre-elimination phase for malaria.
Admiral Tim Ziemer, U.S. Global Malaria Coordinator, said the work of PAHO/WHO member countries and the U.S.-supported Amazon Malaria Initiative have been critical to this success.
"The majority of the progress has been made by host country financing, which has been complemented by modest external funding by donors," said Ziemer. "In addition to the funding, we have seen improving collaboration across the full spectrum of partners."
In another significant achievement, Colombia last year became the first country to be verified as having eliminated onchocerciasis (also known as river blindness), which is carried by black flies. Key support for onchocerciasis elimination has been provided by the Onchocerciasis Elimination Program in the Americas (OEPA), an initiative led by the Carter Center that works with ministries of health to provide health education and channels Merck's donations of the antiparasitic drug Mectizan for mass administration to people at risk of the disease.
"OEPA is a wonderful example of international cooperation in this hemisphere to eliminate a disease," said Donald Hopkins, VP for Health Programs at The Carter Center. "The aim of course is to eliminate river blindness in the Americas, and we are very close to accomplishing that."
Jarbas Barbosa, Secretary of Health Surveillance of Brazil, described his country's efforts to fight dengue, a disease that was largely controlled in the mid 20th century but that resurged in the Americas between 1970 and 2000 following declining investments in vector control. Brazil has taken an integrated approach to the disease, Barbosa said, with significant investment in improving water and sanitation services for the population at risk.
The PAHO/WHO call to action for World Health Day 2014 calls on governments, communities, individuals and donors to take action toward further progress and to face future threats from vector-borne diseases. "Everyone has a role to play," said Etienne.
PAHO, founded in 1902, is the oldest international public health organization in the world. It works with its member countries to improve the health and the quality of life of the people of the Americas. It also serves as the Regional Office for the Americas of WHO.
10 vector-borne diseases that put the population of the Americas at risk
Dengue: a potentially lethal disease transmitted through the bites of infected mosquitoes
Dengue and the Aedes aegypti mosquito are present in all countries of the Americas except Canada and continental Chile. Uruguay has no cases but does have Ae. Aegypti
About 500 million people are at risk in the Americas
Incidence rose from 16 cases per 100,000 people to 218 cases per 100,000 between 1980 and 2000-2010.
In 2013 (an epidemic year) there were 2.3 million cases (430.8 per 100,000) and 1,280 deaths in the hemisphere.
Malaria: caused by the Plasmodium parasite, transmitted through bites of Anopheles mosquitoes
Present in 21 countries of the Americas
145 million people in the region at risk of contracting the disease
Cases declined 60% and deaths 72% between 2000 and 2012
Argentina, Belize, Costa Rica, Ecuador, El Salvador, Mexico and Paraguay are in the process of eliminating malaria
Chagas: a parasitic disease caused by T. cruzi and transmitted mainly through the bites of the so-called "kissing bug"
Present in 21 countries of the Americas
65 million people in the region live in areas of exposure
An estimated 6-8 million people are infected in the region
Each year, an average 28,000 cases are reported, and 8,000 newborns become infected in the Americas
Leishmaniasis: caused by the protozoan parasite Leishmania, transmitted through mosquito bites
Present in 19 countries of the Americas
4 of the 10 countries in the world that report 75% of all cutaneous cases are in the Americas: Brazil, Colombia, Peru and Nicaragua
An average 60,000 cases of cutaneous and mucosal leishmaniasis are diagnosed each year in the Americas, and 4,000 visceral cases, with a case fatality rate of 7%.
Schistosomiasis: a chronic parasitic infection caused by small worms
In the Americas, nearly 1.6 million children need preventive medication
Endemic in Brazil, Venezuela, Suriname and Santa Lucia
Suriname and Santa Lucia are close to interrupting transmission
Available information indicates transmission has been interrupted in the Dominican Republic, Puerto Rico, Montserrat, Antigua, Martinique and Guadaloupe
Yellow fever: an acute viral hemorrhagic disease transmitted by infected mosquitoes
Globally there are some 200,000 cases yearly, causing 30,000 deaths
From 2000 to 2013, more than 1,100 confirmed cases were reported in the Americas
Cases were reported from 13 countries in this hemisphere
From 1985 to 2012, 95% of all cases in the region were reported by Peru (54%), Bolivia (18%), Brazil (16%), and Colombia (7%).
Chikungunya: a viral disease transmitted by mosquitoes
Found for the first time in the Americas in December 2013
By March 2014, had spread to Anguilla, British Virgin Islands, Dominica, French Guiana, Guadeloupe, Martinique, St. Barthelemy, St. Martin/St. Maarten. Aruba has reported one imported case
More than 15,000 suspected cases have been reported in the Caribbean.
Lymphatic filariasis: a parasitic infection caused by worms and transmitted by Culex mosquitoes in the Americas
Some 13.4 million people in the Americas are at risk of infection, 80% of them in Haiti
Endemic in Brazil, the Dominican Republic, Guyana, and Haiti
Guyana, Haiti, and the Dominican Republic provide mass administration of donated drugs for the disease
Brazil has eliminated it in six states, with part of the metropolitan area of Recife now the only active area
Onchocerciasis (river blindness): a parasitic disease transmitted by black flies
Blindness from onchocerciasis has been eliminated in the Americas since 1995
Colombia became the first country in the world to achieve verification of elimination of onchocerciasis transmission in 2013.
Ecuador submitted a request for verification of elimination to PAHO/WHO in 2013
West Nile virus: transmitted to people primarily through the bite of infected mosquitoes.
Eight in 10 people who become infected with WNV show no symptoms
286 people in the United States died of WNV in 2012 (CDC)
Preliminary data for 2013 indicate over 1,200 cases of neuroinvasive disease and 114 deaths due to WNV