Wolbachia, a new weapon amidst the widespread spread of dengue fever
The success of trials of wolbachia-bearing mosquitoes in Indonesia in fighting dengue fever may be underestimated. The decline in infections is predicted to be greater than previously reported at 77 percent.
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The following article was translated using both Microsoft Azure Open AI and Google Translation AI. The original article can be found in Wolbachia, Senjata Baru di Tengah Meluasnya Penyebaran Demam Berdarah
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Officers carried out fogging at the Nusa Loka BSD housing complex, Lengkong Gudang Timur, Serpong, South Tangerang, Banten, Monday (21/8/2023). Fumigation is carried out to prevent the spread of dengue hemorrhagic fever which is transmitted through the bite of the Aedes aegypti mosquito.
JAKARTA, KOMPAS - The spread of dengue fever is increasing, including in subtropical regions, as a result of climate change that expands the movement of mosquitoes. Nevertheless, the fight against the disease has a new weapon, namely mosquitoes that are infected with Wolbachia bacteria.
In trials conducted in Indonesia and Colombia, mosquitoes infected with the Wolbachia bacteria were found to be effective in preventing the spread of disease.
The researchers from the University of Notre Dame recently analyzed a randomized control trial conducted by the World Mosquito Program on wolbachia-infected mosquitoes in Indonesia.
The analysis aims to see how exceptions in the transmission dynamics will affect the original interpretation of the results of this trial.
Also read: Wolbachia Technology Promises for Dengue Control
"The randomized controlled trial is the gold standard for evaluating the effectiveness of medical or public health interventions," said Alex Perkins, a biology professor at Notre Dame and senior author of this study, in a written statement on Monday (11/6/2023)."
Health cadres together with WMP Yogyakarta prepared buckets filled with Wolbachia-carrying mosquito eggs in Padukuhan Ngringin, Condongcatur, Sleman regency, Yogyakarta Special Region.
"This is very difficult to do for vector intervention against dengue fever because this disease occurrence cannot be predicted and is sporadic, therefore requiring a large-scale trial," he said.
The research results of Perkins and his team published in BMJ Global Health used mathematical models to analyze the transmission of the dengue virus that causes dengue fever during trials in Indonesia.
They explore three biases or potential sources of error, which are the subject of this trial. The three biases include human movement, mosquito movement, and the combined dynamics of transmission between human and mosquito movement.
Researchers explain that the most problematic aspect to control is the transmission coupling. Although biases resulting from human movement and mosquitoes can be reduced through trial design and other statistical methods, the coupling of transmission requires mathematical modeling, which is usually not part of clinical trial analysis.
The wolbachia method being researched in Yogyakarta, Indonesia, to tackle dengue-infected diseases, contributes significantly to the world.
This study found that the amount of bias created in the trial is likely to be greater when the population receiving the intervention in this trial is larger.
In Indonesia's trial, almost half of the population received wolbachia mosquito intervention. "This makes the bias we found due to transmission coupling very important in this trial," said Perkins.
Also read: World Recognition of the Wolbachia Method
Although trials of wolbachia in Indonesia showed a reduction in dengue fever infections of only 77 percent, Perkins' team estimates that these results may be underestimated.
Consistent with their predictions, recent trials in Colombia have shown a decrease in dengue fever incidence of 94-97 percent using the interrupted time series approach.
"Despite not showing an accurate revision estimate from trial testing in Indonesia, we show that the efficacy approaching the results observed in the interrupted time series analysis from Colombia can theoretically occur," said Perkins.
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The World Mosquito Program has begun a campaign to control and prevent dengue hemorrhagic fever in Bali using the Wolbachia method. Examples of larvae and mosquitoes were showcased during the launch of the Wolbachia method campaign and training for mosquito larvae monitors in Denpasar on Tuesday (6/6/2023).
"I am very surprised to see the results of this updated timeline, which continues to show the promising approach of wolbachia."
Perkins also noted that the decline in dengue fever cases may not be permanent. Events such as birth, death and immigration will increase vulnerability to the disease, affecting the number of cases in the long term.
I was very surprised to see the results of this updated timeline, which continues to make the wolbachia approach look promising.
Regarding future research on vector-borne diseases, Perkins explained the importance of incorporating dynamic transmission modeling in the design and interpretation of experiments to ensure that researchers understand the actual impact of each intervention.
Also read: Adi Utarini, Dengue Fever Researcher from UGM Who is Recognized Worldwide
“Our findings can be applied to the efficacy of any vector control method that could potentially contaminate a study population, such as mosquito gene drives or ivermectin as interventions against malaria,” said Perkins.
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Head of Rejowinangun Village, Wulan Purwandari, placed a bucket containingAedes aegypti mosquito eggs with wolbachia at the launch of the plan to expand the benefits of mosquitoes with wolbachia in Yogyakarta City at the Rejowinangun Village office, Kotagede, Yogyakarta, Wednesday (2/9/2020).
Expands to Europe
A report in Nature on October 31 2023 stated that fever attacks are currently surging in southern Europe. The disease has spread among the people there and reached areas that had never been affected by the disease before.
Mosquito-borne diseases, which can trigger fever, headache, and fatigue, and kill 40,000 people annually, are not endemic in Europe. Most cases or outbreaks originate from travelers who contract the virus abroad and bring it back with them.
However, this year, a combination of warm weather conditions and an increase in the number of imported cases triggered a surge in local infections carried by the tiger mosquito (Aedes albopictus), which inhabits southern Europe.
“This situation requires a lot of attention,” Patricia Schlagenhauf, an epidemiologist at the University of Zurich, Switzerland, told Nature.
On October 27, 2023, France reported 1,414 cases of imported dengue fever. However, only 217 imported cases were reported in 2022 and 164 cases in 2021.
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World Mosquito Program (WMP) Yogyakarta staff fed Aedes aegypti mosquitoes containing wolbachia bacteria, Tuesday (26/2/2019), at the WMP Yogyakarta Entomology Laboratory, Sleman Regency, Special Region of Yogyakarta.
Apart from imported cases, the presence of the A albopictus mosquito which transmits the virus means there is local infection. When infected tourists are bitten by these mosquitoes after they return, the insects now carry the virus in their bloodstream and can transmit the disease to other people they bite.
A albopictus mosquitoes breed at temperatures between 15 degrees Celsius and 35 degrees Celsius and can breed in small amounts of standing water. With the presence of this mosquito, local transmission has occurred in Southern Europe.
According to the European Centre for Disease Prevention and Control, on October 25, 2023, a total of 105 cases of local transmission have been reported in Southern Europe, including 66 cases in Italy, 36 patients in France, and 3 individuals in Spain.
The outbreak of locally transmitted dengue fever in Italy, which has the largest population of A. albopictus in Europe, is centered around the Lombardy and Lazio regions and includes 28 cases in Rome.
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Head of Rejowinangun Village, Wulan Purwandari, carries a bucket containing Aedes aegypti mosquito eggs containing wolbachia at the launch of the plan to expand the benefits of wolbachia mosquitoes in Yogyakarta City at the Rejowinangun Village office, Kotagede, Yogyakarta, Wednesday (2/9/2020).
In France, the number of locally transmitted cases is lower compared to 2022. However, the epidemic is now spreading to Auvergne-Rhône-Alpes and Île-de-France, areas that have never reported any cases of local transmission. As 50-90 percent of people are asymptomatic, the incidence of dengue fever is likely to be higher than reported.
