Vector-Borne Diseases

Vector-borne diseases are illnesses caused by pathogens (viruses, bacteria, or parasites) that are transmitted to humans and other animals by vectors, such as mosquitoes, ticks, fleas, and flies. These diseases are widespread and pose a significant public health threat worldwide, with over 700,000 deaths annually. They primarily affect tropical and subtropical regions, where environmental factors like climate and weather significantly influence the reproduction rates of these vectors.

Key Points on Vector-Borne Diseases:

1. Global Impact:

   • Over 700,000 deaths annually from vector-borne diseases.

   • 17% of infectious diseases globally are vector-borne.

   • Tropical and sub-tropical regions are the most affected, with the poorest populations being most vulnerable.

2. Major Diseases:

   • Malaria: Caused by Plasmodium species and spread by mosquitoes.

   • Dengue, Chikungunya, Zika: Caused by various viruses transmitted by mosquitoes.

   • Filariasis, Yellow Fever, West Nile Fever: Also spread by mosquitoes.

   • African Trypanosomiasis: Caused by Trypanosoma brucei and transmitted by Tse-tse flies.

   • Leishmaniasis, Phlebotomus Fever: Caused by Leishmania and spread by sandflies.

   • Lyme disease, Crimean-Congo Haemorrhagic Fever: Spread by ticks.

Common Vectors and the Diseases They Spread:

Vector-Borne Diseases in India:

In India, vector-borne diseases like malaria, dengue, and chikungunya are significant public health concerns. Malaria remains the most common and critical disease, with approximately 2 million cases reported annually, particularly in rural areas and states like Orissa, Uttar Pradesh, Jharkhand, and Chhattisgarh.

The World Bank Supported Vector-Borne Disease Control Project focuses on malaria control through the use of advanced technologies and medicines, especially in endemic regions. This initiative aims to reduce malaria incidence and improve healthcare access in impoverished areas.

Prevention of Vector-Borne Diseases:

1. Personal Protection:

   • Vaccines (e.g., for yellow fever, malaria).

   • Insect repellents (DEET, Permethrin on clothes).

   • Tick checks after exposure to areas with dogs, cattle, or mice.

   • Nets while sleeping to prevent mosquito bites.

   • Wash and dry clothes after outdoor visits.

2. Environmental Control:

   • Remove leaf litters, woodpiles, and stagnant water where vectors breed.

   • Use disinfectants to kill pests.

National Vector Borne Disease Control Programme (NVBDCP):

The NVBDCP is an umbrella organization established to manage vector-borne diseases in India. It targets six major diseases: malaria, chikungunya, dengue, Japanese encephalitis, kala-azar, and lymphatic filariasis. This programme focuses on surveillance, vector control, and public education on preventive measures.

Nexus Between Climate Change and Malaria:

Climate change plays a significant role in the spread of vector-borne diseases. Changes in temperature, humidity, and rainfall influence the reproduction and survival of vectors like the Anopheles mosquito, which spreads malaria.

• Extreme weather events, such as heatwaves and flooding, can significantly increase malaria transmission. For example, the 2022 flooding in Pakistan resulted in a five-fold increase in malaria cases.

• Malnutrition caused by climate change is a risk factor for severe malaria, especially among children and pregnant women.

Recent Developments in Malaria Prevention:

1. R21/Matrix-M Malaria Vaccine: In 2023, the R21/Matrix-M malaria vaccine was recommended by WHO for use in children, marking a significant step in malaria prevention.

Challenges in Malaria Control:

While progress has been made in reducing malaria cases in countries like India, there are several challenges:

• Climate change: Alters mosquito behavior and extends the transmission season.

  Conflict and humanitarian crises: Disrupt healthcare systems and exacerbate disease spread.

  Resource constraints: Limited access to healthcare and vector control measures.

  Biological challenges: Emergence of drug-resistant malaria strains and insecticide resistance in mosquitoes.

Conclusion:

Vector-borne diseases remain a significant challenge for global public health. Climate change, resource limitations, and biological resistance complicate efforts to control these diseases. While India has made strides in reducing malaria cases, the ongoing challenges require sustained efforts in prevention, surveillance, and treatment.