Mosquito surveillance in Madagascar reveals new information on malaria transmission

The Ministry of Public Health in Madagascar has reported thousands of cases of malaria in recent months. In March, more than 600 cases of malaria were reported each week and at least 2,000 cases were reported in less than a month. As a result, efforts have been made to stop the epidemic.

At present, a team of researchers from the Case Western Reserve University School of Medicine has discovered new discoveries about malaria transmission in Madagascar. They described the practical application of a cost-effective mosquito surveillance strategy using inexpensive traps and a new tool for testing each mosquito to determine its species, the presence of malaria parasites and its diet.

Madagascar's National Malaria Control Plan 2018 (NSP) outlines pre-elimination strategies for malaria control that include detailed targets for mosquito control. The researchers aim to strengthen malaria prevention through mosquito surveillance. Therefore, they conducted the study, published in PLOS Neglected Tropical Diseases, in isolated villages of Madagascar.

Results of mosquito surveillance

They found that female mosquitoes of the Anopheles species had more varied diets than those known until now. The results can pave the way for a better understanding of the transmission of the disease and the formulation of new strategies for the prevention of malaria.

Anopheles mosquito. Image Credit: Kletr / Shutterstock

The researchers used a modified filter trap called QUEST (Quadrant Enabled Screen Trap), with a BLOOdmeal multiplexed detection test for newly developed regional transmission (BLOODART). During the study, the researchers captured 1,252 Anopheles mosquitoes. All mosquitoes underwent BLOODART badysis.

The mosquito feeding mode was badyzed and revealed multiple hosts of the blood meal. The most common mosquito host was a cow, then a pig and humans. Subsequently, researchers found that the trend of mosquitoes feeding on humans increased between December 2017 and April 2018, from 27% to 44%. The results suggest that the home care preferences of these mosquitoes vary from season to season, suggesting that surveillance and eradication efforts may occur. needed.

"The QUEST was an effective tool for sampling exophile Anopheles mosquitoes. Vectors considered to be of secondary importance were generally found with Plasmodium DNA in the abdomen, indicating the need to consider these species in routine surveillance efforts, "concluded the researchers of the study.

"Mosquitoes exhibited multiple blood-feeding behaviors during a gonotrophic cycle, with predominantly nonhuman hosts in the blood meal. Taken together, this complex feeding behavior may reinforce the role of several Anopheline species in malaria transmission, possibly tempered by zoophilic food trends, "they added.

The use of QUEST, the modified mosquito net trap and outdoor can be used in addition to existing mosquito control techniques.

"Outdoor trapping can capture species that other sampling methods might miss," said Dr. Riley Tedrow, a medical entomologist at Case Western Reserve University's School of Medicine. .

Tedrow also reiterated the importance of BLOODART, which combines an existing malaria screening test with a technique for determining mosquito species. This technique allows scientists to evaluate hundreds of mosquitoes, their food sources, the presence of malaria parasites and species.

What is malaria?

Malaria is a tropical disease caused by a parasite. Malaria parasites that usually infect humans include Plasmodium falciparum, Plasmodium vivax, Plasmodium oval, and Plasmodium malariae. however, Plasmodium falciparum is the type of malaria that can lead to a serious infection and that, if left untreated, can lead to death.

Plasmodium falciparum 3d illustration – Credit: Sciencepics / Shutterstock

The infection is a life-threatening disease and the parasites are transmitted to people through the bites of infected female Anopheles mosquitoes. Although it can be life threatening, it is curable and preventable.

In 2017 alone, there were approximately 219 million cases of malaria in 87 countries. About 445,000 people died of malaria, most of them are African children. In the United States, approximately 1,700 cases of malaria are diagnosed each year. Most of these cases are travelers or immigrants returning from malaria-affected countries, such as South Asia and Sub-Saharan Africa.

Signs and symptoms of malaria include flu-like illness, muscle pain, headache, chills, and fatigue. Other symptoms may appear, such as vomiting, nausea and diarrhea. Some complications may occur, such as jaundice and anemia, due to the loss of red blood cells. In severe cases and if the disease is not treated quickly, it can lead to seizures, kidney failure, mental confusion, coma and even death.