Disease Focus

The Spatial Repellents Program will focus on two human diseases of global presence and importance - dengue fever and malaria. Both diseases are found in tropical environments worldwide. According to the World Health Organization, 214 million cases of malaria were reported in 2015, with 50 million to 100 million dengue infections occurring every year. Both the malaria parasite and dengue virus are transmitted through the bites of infected mosquitoes. Although vaccines are being developed and optimized for these diseases, the prevention of mosquito biting and early recognition and treatment of infections are the primary methods to reduce disease burden.

Malaria

malaria_map

anopheles_freeborni

Source:  cdc.gov - Centers for Diseases Control and Prevention. 

Malaria is transmitted exclusively through the bites of Anopheles mosquitoes. When the bite of the female mosquito introduces the parasites into a person’s blood, the parasites travel to the liver where they mature and reproduce, infecting the red blood cells. The intensity of transmission depends on factors related to the parasite, the vector, the human host, and the environment.

The incubation period takes between 7 to 30 days and leads to a wide variety of symptoms, ranging from absent or very mild symptoms, to severe disease and even death. If the first symptoms-fever, headache, chills and vomiting- are not treated within 24hours, they can progress to severe illness or death. Children with severe malaria frequently develop one or more of the following symptoms: severe anemia, respiratory distress in relation to metabolic acidosis, or cerebral malaria.

In general, malaria is a curable disease if diagnosed and treated promptly and correctly but severe disease occurs with 90% of the malaria deaths in Africa.

 

Dengue

dengue_map_cdc

Source:  cdc.gov - Centers for Diseases Control and Prevention.

aedes_aegypti

Dengue fever is caused by one of the four closely related dengue viruses (DENV 1, DENV 2, DENV 3, or DENV 4) and is transmitted to people by the bite of an Aedes mosquito.

The principal mosquito vector of dengue viruses is Aedes aegypti, also called the yellow fever mosquito. Aedes aegypti is a small dark mosquito with with lyre shaped markings and banded legs. They prefer to bite indoors, mostly on mammals and especially humans, and primarily bite during the daytime.

Infected persons can either have symptoms of dengue fever or Dengue Hemorrhagic Fever (DHF), or they may have no symptoms at all. DHF is a more severe form of dengue fever. The incubation period is between 4 and 10 days for the first symptoms: fever, headache, pain behind the eyes, appetite loss, muscle and joint pain, and rash. Persons experiencing DHF can also develop liver or heart problems, bleeding under the skin, from the nose or the gums, and breathing difficulty. Generally, younger children and those with their first dengue infection have a milder illness than older children and adults.

Recovery from infection by one dengue virus serotype provides lifelong immunity against that particular serotype. There is no specific treatment for dengue, and mosquito control remains the primary strategy for prevention of human infections.