Leptospirosis, a potentially fatal bacterial disease, is increasingly common during monsoon months. A significant occupational hazard for those working in agricultural settings or sanitary services, it leads to contact with contaminated water. Alongside, public health experts warn of a potential severe outbreak of dengue necessitating enhanced clinical and virological surveillance. Changes in circulating dengue virus serotypes could lead to more severe, life-threatening conditions. Thiruvananthapuram district, Kerala, reported 70% of dengue case samples in 2022 were DENV3, while some were DENV4.
Understanding Leptospirosis
Leptospirosis, caused by the bacterium Leptospira interrogans, is primarily found in the urine of infected animals. Both wild and domestic creatures like rodents, cattle, pigs and dogs serve as carriers of the disease.
Its symptoms range from mild flu-like illness to life-threatening conditions that might include sudden fever, chills, headache and even organ dysfunction affecting the liver, kidneys, lungs and brain. In some cases, there are no symptoms at all.
Transmission begins with infected animals shedding leptospira in their urine. Direct contact with this infected animal urine or indirect contact through contaminated soil and water puts people, especially those with skin cuts or abrasions, at risk.
Preventing Leptospirosis
Preventing animal infection, maintaining hygienic animal-keeping conditions, proper waste management, and improved sanitation facilities are key to curbing leptospirosis’s spread and reducing farmers’ economic losses. The adoption of a ‘One Health’ approach considering human, animal, plant, and environmental health interconnectedness is critical to controlling leptospirosis.
While a common misconception associates leptospirosis solely with rats, it can be transmitted by multiple animal reservoir hosts.
Dengue: A Closer Look
Dengue, a tropical disease, is caused by the dengue virus (Genus Flavivirus). It’s transmitted by several mosquito species within the Aedes genus, primarily Aedes aegypti, which also transmits chikungunya and Zika infection.
The virus causing dengue has four closely related serotypes (DEN-1, DEN-2, DEN-3, and DEN-4). Typical symptoms include sudden high fever, severe headaches, pain behind the eyes, severe bone, joint and muscle pain.
Dengue Vaccine Developments
Researchers in India, Africa, and the US have developed India’s first and only DNA vaccine candidate for dengue fever. The US Food & Drug Administration approved the first dengue vaccine, Dengvaxia, in 2019. Dengvaxia, a live attenuated dengue virus, should be administered to people aged 9 to 16 years who previously had a laboratory-confirmed dengue infection and living in endemic areas.
Developing an effective dengue vaccine is challenging due to the four closely related virus serotypes, each interacting differently with antibodies. An ideal vaccine should target all serotypes while avoiding antibody-dependent enhancement (ADE), where antibodies aid the virus, causing severe disease.