A Prospective & Retrospective View On The Burden Of Mosquito-Borne Diseases In India
Most parts of India witnessed unseasonal and intense rainfall in the last few weeks. The stagnant rainwater provided breeding grounds for mosquitoes, resulting in a spike in dengue and malaria cases causing more than 700,000 deaths worldwide every year.?
Mosquito is one of the most widespread disease-causing organisms acting as vectors, transmitting deadly diseases. According to the WHO (World Health Organization), vector-borne diseases account for more than 17 per cent of all infectious diseases and every year cause more than 700,000 deaths worldwide.? WHO has set a target to reduce malaria incidence and mortality rates by 90% by 2030 by setting communications, eating awareness and strengthening the surveillance of the mosquito-borne disease around the world.?
?Epidemiology Of Malaria & Dengue?
Malaria is a life-threatening disease caused by parasites that are transmitted to people through the bites of infected female Anopheles mosquitoes. In 2020, there were an estimated 241 million cases of malaria worldwide and the estimated number of malaria deaths was 627,000. Dengue is another prevalent viral infection that caused an estimated 40,000 deaths every year.? The global incidence of dengue has escalated quickly with about half of the world's population now at risk. Dengue and malaria mainly occur in tropical and sub-tropical climates worldwide. ?
India stands as the 11th malaria burden country in the world, and in 2020, it accounted for about 86% of all malaria deaths in the South-East Asia region. In India, the distribution of vectors and malaria endemicity largely depends on the physiographic, climatic and socio-developmental conditions that vary from area to area. Temperature and rainfall influence the life cycle of mosquito-borne diseases. Epidemic outbreaks can occur as a result of climate anomalies, such as prolonged periods of rainfall (except rainfall extremes where flushing of mosquito larva becomes important) and in regions where malaria transmission is strongly seasonal such as semi-arid or highland regions. ?
?The northern part of the country is characterized by a subtropical climate and increase in altitude towards the north and has a high variation of temperature between summer and winter with only a brief rainy season.?
The southern part of India has a tropical climate and is surrounded by seas; the temperature varies little throughout the year and receives significant monsoonal rains.?
The northeastern states are characterized by the Himalayan ranges receiving heavy annual rainfall, a most conducive temperature, and thus stable malaria transmission. ?
The western states, particularly Rajasthan, Gujarat and parts of Karnataka, are mainly plain areas, receive scanty rainfall, and are prone to malaria outbreaks.?
An increase in temperature, rainfall, and humidity may cause a proliferation of malaria-carrying mosquitoes at higher altitudes, resulting in an increase in transmission. At lower altitudes where malaria is already a problem, warmer temperatures will alter the growth cycle of the parasite in the mosquito enabling it to develop faster, increasing transmission and thus having implications on the burden of disease.?
To reduce this burden, the Indian government introduced its National Framework for Malaria Elimination in 2016 and is now focused on eradicating malaria by 2030.?
The Burden of Mosquito-borne Diseases in India - Real-World Evidence (RWE) ?
?THB has collated real-world data on the number of positive cases and zone-wise positivity percentage for the three major mosquito-borne diseases prevalent in India. The data was collected from 606,992 individuals (Male-337,169; Female-269,823) for Chikungunya, Dengue, and Malaria for the year 2021.:?
As per THB’s RWE (Real World Evidence) data study the following observations were made:?
North - High incidence of Dengue & low incidence of Chikungunya & Malaria was observed ?
East - Highest burden of Dengue; while there is low incidence of Malaria ?
Central - High incidence of Dengue, and highest burden of Malaria than other parts of the country?
West - Chikungunya was more incident than other parts of the country?
South - High incidence of Dengue with a low incidence of Malaria ?
?How can a single mosquito bite cost your life??
Globally, Malaria has impacted the most and the parasite responsible for the most prevalent and severe cases is Plasmodium Falciparum.? The Anopheles mosquitoes that transmit malaria are widespread throughout tropical regions of the world. The unique biology of the malaria parasite helps it to reproduce and jump from one person to another. The mosquito first takes up the parasite while feeding on the blood of a person with malaria. Next, the parasite migrates through the mosquito’s body, infecting the salivary glands of the mosquito, from?which it is injected into another human through the mosquito’s bites. In this human, the parasite undergoes additional developmental stages in its life cycle. It can lead to the appearance of symptoms like fever and chills along with nausea, vomiting, headaches, muscle and joint aches, and fatigue.?
Who are the people at high risk & associates with complications of mosquito-borne diseases??
Malaria – Malaria is a life-threatening disease, in 2020 half of the world’s population was at risk of Malaria.? In cases of severe malaria, children and pregnant women are at higher risk of getting infected.?
The disease can be evident as cerebral malaria with seizures or coma and might cause serious complications such as severe anaemia, respiratory distress, kidney and liver failure, cardiovascular collapse, shock, and death. If the mosquito does not act as an intermediary for the malaria parasite, it could not be transmitted between people.?
Chikungunya- Chikungunya virus is primarily transmitted to people through the bite of an infected mosquito, Aedes aegypti and Aedes albopictus. Humans are the primary host of the chikungunya virus during epidemic periods. The mosquitoes become infected when they feed on a person who already has the virus.??
India has experienced 2 major outbreaks of Chikungunya viral (CHIKV) fever outbreaks over the last decade, with higher mortality rates during the year 2016. People living near stagnant water areas, in hot & humid climates, immunocompromised, pregnant, elderly (>65 years) or have co-existing medical conditions such as diabetes, blood pressure & respiratory disease are at higher risk of developing this viral infection. ?
Chikungunya is rarely fatal, but the symptoms can be severe, long-lasting, and debilitating causing several serious complications such as uveitis, retinitis, hepatitis, loss of function in the cranial nerves and inflammation of the spinal cord.?
Dengue- Every year approximately 390 million dengue infections occur worldwide resulting in the illness of 96 million people. Most cases are found in tropical areas of the world, with the Indian subcontinent and Southeast Asia being the most prone areas. Dengue viruses spread to people through the bites of infected Aedes species mosquitoes which are responsible for transmitting chikungunya and zika. Sudden high fever, severe headache, joint pain, and skin rash are some of the common symptoms. People with weakened immune systems as well as those with a second or subsequent dengue infection are believed to be at greater risk for developing dengue haemorrhagic fever. ?
Dengue if not treated early has a high sign of causing serious complications such as, Haemorrhage (Dengue haemorrhagic fever), heart failure, kidney failure, pleural effusion, brain haemorrhage preterm birth or miscarriages in pregnant women. ?
Prevention - Fight The Bite?
Tips To Prevent Mosquito-Borne Diseases:?
Conclusion ?
According to studies, global efforts against mosquito-borne diseases have saved more than 7.6 million lives and prevented over 1.5 billion malaria cases since 2000. However, mosquito-borne diseases are still widespread even today and are difficult to treat. If we stay the course in our commitment to creating awareness and leveraging new methods ending malaria is possible. It is time to invest, innovate and investigate the newer treatment methods and vector control approaches. New technologies for battling mosquitoes and the diseases they carry are urgently needed. Raising awareness amongst communities, learning about mosquito-borne diseases, timely diagnosis and evaluating new vaccines are some of the ways in which we can reduce the burden of malaria and save lives.?
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