Lassa fever: understanding the risks, responses, and global threat

Lassa fever is a zoonotic disease belonging to the Arenaviridae family. must miss Rodents are the main reservoir | Photo credit: Robert Taylor, CC BY 4.0 via Wikimedia Commons

The story so far

Lassa fever, a viral hemorrhagic disease, has been in the spotlight following a recent incident in the US state of Iowa in which a tourist from West Africa died. Lassa fever has been reported in Benin, Ivory Coast, Ghana, Guinea, Liberia, Mali, Nigeria, Sierra Leone, and Togo. Although the disease was first identified in 1969 in the town of Lassa, Nigeria, the disease continues to pose a serious health threat, affecting an estimated 100,000 to 300,000 people annually and approximately 5,000 deaths each year. has died. The Indian Ministry of Health and Family Welfare has classified Lassa fever as a disease of international importance. India has not recorded any documented cases to date (officially, no cases will be reported until 2022). However, recent events in the United States highlight the need for aggressive measures to prevent the potential spread of infection through international travel.

What is Lassa fever?

Lassa virus causes Lassa fever, a zoonotic disease belonging to the Arenaviridae family. must miss Rats are its main holders. Humans usually become infected with the virus through contact with food or objects contaminated with rodent urine or feces. Person-to-person secondary transmission occurs through exposure to body fluids and poses a significant risk, especially in healthcare settings. The most common symptoms of Lassa fever begin with a gradual onset of fever, general weakness, and malaise, followed by headache, sore throat, muscle pain, chest pain, nausea, vomiting, diarrhea, cough, and diarrhea after a few days. More severe symptoms appear. And abdominal pain. About 80% of infections are asymptomatic or mild, but severe cases can cause high fevers, severe headaches, and bleeding, which can lead to organ failure.

The overall case fatality rate (CFR) for Lassa fever is approximately 1%. However, in hospitalized patients, CFR can increase to 15-20%. Notable sequelae include varying degrees of hearing loss that occur in nearly 25-50% of patients 1-3 months after recovery. RT-PCR and ELISA tests are required for a definitive diagnosis. Trained personnel must handle samples according to strict biosafety level 4 (BSL-4) protocols for virus isolation. This barrier limits the ability to diagnose widespread Lassa fever, especially in areas with poor health systems.

Lassa fever poses a particularly serious risk to pregnant women and infants. Infected pregnant women, especially those in the third trimester, have an increased risk of maternal mortality of more than 30%. The effects of this disease on the fetus are severe, with fetal mortality rates exceeding 85%. In children up to 2 years of age, Lassa fever may manifest as “infant swelling syndrome.” It is characterized by extensive swelling and is associated with a higher mortality rate than in adults. Vertical transmission of Lassa fever from mother to fetus has been reported.

What does treatment and vaccine development look like?

Intensive supportive care for Lassa fever includes careful monitoring of fluid and electrolyte balance and assessment of renal function, with careful hydration playing an important role. Supportive care includes the use of painkillers to manage discomfort, antiemetics to control vomiting, and anxiolytics to manage agitation. In addition, antibiotics and antimalarials may be given as needed to manage potential co-infections. To increase survival rates, the antiviral drug ribavirin should be administered in the early stages of the disease.

Vaccine development for Lassa fever faces multiple obstacles. The genetic diversity of this virus is characterized by at least five known lineages, complicating the development of a universal vaccine. Additionally, trials testing vaccine efficacy often require sufficient incidence, which can only be achieved during large outbreaks. This limits the timing and practicality of clinical trials. Additional logistical challenges such as high costs, sustainability of vaccine supply, and cold chain requirements will further complicate widespread vaccine deployment. Despite these hurdles, promising research is underway. Preclinical evaluations and early-stage trials have shown progress, with several vaccine candidates progressing to more robust testing stages.

What should the public health strategy be?

An effective public health response requires national leadership to prioritize preparedness, strengthen diagnostic capacity, and ensure the availability of medical supplies. We need to train health professionals in infection control and the use of personal protective equipment (PPE) and strengthen public health systems to improve patient outcomes.

To control Lassa fever, it is essential to minimize transmission from rats to humans. Limited infrastructure, especially in endemic areas, limits efforts to effectively monitor, diagnose, and treat the disease. Effective management strategies focus on preventing human contact with infected rodents through rodent-proof housing, safe food storage, and community education about maintaining hygiene. Person-to-person transmission should be reduced by encouraging early treatment and isolating suspected cases. Healthcare facilities must apply strict infection prevention measures, including the use of PPE and safe handling of patient samples. Governments need to coordinate an effective public health response, mobilize resources for surveillance, and partner with the World Health Organization for expertise and logistical support.

How can I travel safely?

Traveler health is an important aspect of public safety, especially for Indian citizens traveling to areas where the risk of infectious diseases is high. The region is known for diseases such as Lassa fever, yellow fever, and malaria, creating significant health problems. It is essential to ensure proper pre-travel health precautions, including vaccinations, administration of preventive medications, and awareness of local disease outbreaks. The Government of India emphasizes the importance of travelers following the latest health advice, following safety precautions and maintaining good hygiene to minimize risks. This includes strengthening surveillance measures at points of entry, including airports, and recommending post-travel health checks for early detection and management of imported cases.

(Dr. C. Aravinda is an academic and public health physician. aravindaaiimsjr10@hotmail.com)