Data from the Costa Rican Health Ministry for the first nearly five months of 2017 show a decrease in the number of new dengue cases compared to last year. Additionally, last year there were three strains of the virus circulating, and this year only two have been detected.
Atenas and Montes de Oro in the Central Pacific foothills are the top two counties with dengue cases this year. Miramar near Puntarenas is the head of the Montes de Oro county, which has a rate of 252 cases per 100,000 inhabitants this year. Atenas follows with 162 cases per 100,000. These rates are significantly higher than the national infection rate of 23 cases per 100,000.
Five of the top ten dengue counties, or cantons in Spanish, are in the province of Limón, and two are in the Central Pacific and include Garabito county where Jacó is located and other popular tourist beaches.
And, finally, Sarapiqui in the Central Atlantic slope region bordering San Carlos and Limón is one of the top ten dengue zones.
Dengue is a potentially fatal mosquito-borne disease transmitted by the Aedes aegypti mosquito. The insect is very sensitive to environmental factors such as temperature, precipitation and humidity, and the probability of infection goes up when temperatures rise, according to the World Health Organization.
Last year the country registered a total 6,963 dengue cases, and so far this year 1,138 cases. No deaths were reported from the disease last year nor have any been reported this year.
Aedes aegypti mosquitoes generally bite during the day, prefer to lurk indoors, and bite most often in the morning and evening – a single bite from an insect carrying the virus can result in infection. The biting behavior of this mosquito is peculiar: It can bite one without being noticed and usually approaches from behind, biting mainly on the ankles and elbows. The mosquito lay eggs during the day most often in water containing organic material, like decaying leaf, algae, etc.
In Costa Rica, the Ministry of Health has a national campaign to reduce mosquito breeding areas by eliminating trash, most notably discarded tires, as well as instructing people to cover recipients used to store water, to check other recipients in and around their house where rain water might collect, as well as checking plastic tarps used in farming.
Last year the Ministry of Health in their 2016 year-end dengue report said they fumigated over 750,000 houses.
There are five known types of the dengue virus. The first two are currently circulating in Costa Rica.
Dengue accounts for approximately 25,000 deaths every year globally, and an estimated 2.5 billion people – a full two–fifths of the global population – are at risk of infection, said the WHO.
The disease has become endemic in more than 100 countries and is known as break-bone fever.
An infection with dengue will manifest between three and 14 days after being bitten, and can result in either dengue fever, a less serious form, or in dengue hemorrhagic fever (DHF) which can lead to death if not treated immediately.
Symptoms usually start occurring from 4-7 days after infection, and can range from mild to severe. In mild cases it can be mistaken for the flu or another viral infection. Younger children and people who have never been infected before tend to have milder symptoms as compared with those who have already had a dengue infection.
The symptoms generally last for about ten days and can include any of the following: Sudden high fever, severe headache, swollen lymph glands, severe joint and muscle pain, skin rash that appears two to five days after the initial fever, mild to severe nausea, mild to severe vomiting, mild bleeding from nose and gums, bruising, febrile convulsions, pain behind the eyes, drowsiness or irritability, pale, cold and clammy skin, and/or difficulty breathing.
In the hemorrhagic manifestation heavy bleeding can occur from the mouth and nose, and other symptoms can include sharp pain in abdominal area, persistent vomiting for a long time, bleeding under the skin that can look like bruising, problems with lungs, liver and heart, as well as high fever.
DHF most often occurs in people who have had a previous infection, are under the age of 12, and/or have a weakened immune system.
Diagnosing dengue fever can be a difficult task because its signs and symptoms can easily be confused with other tropical diseases such as malaria, leptospirosis, typhoid fever.