Lassa fever – Guinea

Guinean Ministry of Health and Public Hygiene proclaimed a Lassa fever epidemic after laboratory testing of two cases from the Guéckédou region in southeast Guinea. Lassa fever is prevalent in various countries in West Africa, and Guinea has recorded outbreaks and occasional cases. Given that now the Guinean healthcare system has been overloaded by developing and  new outbreaks of infectious diseases since last year, this new epidemic may have a major public health effect. To yet, no fatalities have been recorded.

Description of the case

On 20 April 2022, local health officials were alerted of a suspected case of viral disease in Guéckédou region, southeast Guinea (Figure 1). A 17-year-old girl developed fever and lack of appetite on April 12. From 16 to 17 April, the case complained chest discomfort and physical weakness. On 18 April, the patient requested medical care and was hospitalised on 19 April. The subject got home care for five days after symptom onset and contacted two health institutions, resulting in 141 interactions.

On 20 April, a blood sample from a probable patient was tested at the Guéckédou deadly disease laboratory for Ebola, Marburg, and Lassa disease. The person tested negative for Ebola and Marburg on 20 April but was diagnosed positive for Lassa disease on 21 April. On 22 April, a second test at the research facility in Conakry confirmed positive. On the same day, the Health minister proclaimed a Lassa fever epidemic. The case is now being treated at Guéckédou.

On 28 April, a second recorded case of Lassa fever, with no documented epidemiological relation to the first case, was recorded in Guéckédou prefecture. The instance was a 24-year-old man. On 16 April, he appeared with chest discomfort and sleeplessness and sought treatment at a private clinic on 18 April. On 28 April, he sought treatment at the provincial hospital for fever, migraine, vomiting, thoracic discomfort, and bloody stools. On 29 April, he tested positive for Lassa fever at a Guéckédou lab. Epidemiological research are ongoing to do

Figure 1. Location of known cases (n=2) of Lassa fever in Guinea in April 2022

Epidemiology.

Lassa fever is a severe viral hemorrhagic illness caused by the Lassa virus. It's spread to people either via close contact with infected Mastomys rats or by food or household objects contaminated with their urine or faeces. To a lesser level, transmission may also occur from human-to-human by direct contact with blood or body fluids of an infected individual, usually in a hospital environment owing to inadequate infection prevention and control procedures. Most instances (about 80%) are asymptomatic or moderate, but the virus may cause serious illness in the remaining 20%, with a case fatality ratio (CFR) of around 15% among severely sick individuals. Early supportive treatment for patients enhances survival. There is presently no vaccination for Lassa fever.

Lassa fever is endemic in Benin, Ghana, Guinea, Liberia, Mali, Sierra Leone, and Nigeria and is likely prevalent in additional West African nations. In Guinea, Lassa fever was first identified in October 2011. Since then, outbreaks and sporadic cases have been documented in Guinea. The latest occurrence of Lassa fever in Guinea was in 2021, with 8 cases and 7 fatalities (88 percent CFR) recorded in N'Zérékoré, Beyla, Guéckédou, and Yomou.

Public health responses

The Ministry of Health and Public Hygiene, in conjunction with WHO and other partners, has strengthened preventative operations in the area. The Ministry of Health and Public Hygiene has developed a response plan and is raising money to finance it.

• Delivered medications and case management materials to the field.

• Deployed a fast response team to assist reaction actions.

• Implemented conventional measures, including isolation of suspected patients, laboratory confirmation, infection prevention and control in health institutions, and social mobilisation and community participation.

WHO Risk Assessment

The danger for this outbreak at the national level is substantial since Lassa virus is endemic in the country due to the prevalence of Mastomys rats. In addition, there are limited financial, personnel, and logistical resources, and the Guinean health system has been overburdened since last year. In 2021, Guinea witnessed various emerging and re-emerging infectious illnesses, including Ebola, Marburg, Lassa fever, measles, meningitis, yellow fever, vaccine-derived polio type 1, and COVID-19. This epidemic might have a major effect on public health owing to the poor health system.

Preliminary epidemiological analyses imply there is a possibility of nosocomial and community spread from the initial case.

Regional and worldwide danger of spread is limited owing to the major mechanism of transmission, rodent exposure. Guéckédou lies near the international boundaries with Liberia and Sierra Leone, however the danger of cross-border transfer is minimal. Lassa fever is prevalent in Liberia and Sierra Leone owing to Mastomys rats, therefore exposure is possible in these two nations.

WHO recommendations

Safeguarding in communities: Good communal hygiene is crucial to prevent rodents from invading houses. Effective strategies includes storing corn and other supplies in rodent-proof containers, dumping of rubbish away from houses, keeping dwellings clean, and maintaining cats.

Healthcare settings:

• Health care professionals should always take basic procedures for the prevention and treatment of healthcare-associated infections, regardless of the suspected diagnosis. These precautions include hand hygiene, respiratory hygiene, safety gear, injection safety, and safe burial practises. • Health care workers supposed to care for suspected or known cases of Lassa fever should take extra infection prevention and control steps to avoid interaction with the patient's blood and body fluids and contaminated objects or materials such as clothing and bed linens. When within one metre of patients, they should wear facial protection (face shield or surgical masks and glasses), a clean, non-sterile, long-sleeved robe, and gloves (sterile for certain medical procedures).

In regions where Lassa fever is prevalent, it's crucial to enhance early diagnosis and clinical care of infections to minimise case fatality.

The WHO does not propose any restrictions on travel or commerce in Guinea based on the present epidemiological condition.