Lassa Fever – Are we high risk?
While no cases of Lassa Fever have been reported in South Africa following the recent outbreak in parts of Nigeria, people travelling to affected parts of the country are advised to be cautious as a precautionary measure. News reports state that just over 100 people have died as a result of Lassa Fever in parts of Nigeria since August last year. According to the World Health Organization (WHO), four of the most affected states reported are Bauchi, Edo, Oyo and Taraba. Professor Lucille Blumberg, the deputy-director of the National Institute for Communicable Diseases (NICD), said there has been an increase in the number of cases in Nigeria and cases have also been reported in Burkina Faso. “These are not common areas that tourists generally visit. It is important however, for people to be aware,” she said. Lassa Fever is an acute viral haemorrhagic illness. The arenavirus is transmitted to humans through contact with food and objects such as household equipment that has been contaminated by urine or faeces of a rodent of the genus Mastomys, known as the multimammate rat. Person to person transmission occurs through direct contact with the blood, faeces, urine and other bodily secretions of an infected person. Not all Mastomys rats are infected with the virus. Most are not, and Lassa has not been found in rodents in South Africa. Initial symptoms occur about one to three weeks after a person contracts the virus. In cases where people have symptoms, these may include high fever, vomiting, diarrhoea, weakness, a sore throat, cough, back pain and conjunctivitis. In severe cases, the virus could result in facial swelling, coma, seizures, bleeding from the nose or mouth and can affect body organs such as the liver and kidneys as well as lead to death. There is no vaccine against Lassa Fever, which is endemic to many parts of West Africa including Sierra Leone, Guinea and Liberia. A drug called Ribavirin is used to treat infected people. “Lassa has not been found in rodents in Southern Africa and South Africa. A new related virus, Lujo virus, caused a small outbreak in 2008. One case imported from Zambia infected four health workers in a Johannesburg hospital due to direct transmission from body fluids. The specific virus was not found in rodents studied in Zambia and has never been seen again after this small outbreak. The source remains unknown. So, overall there is a very low risk of introduction of Lassa into South Africa. There was one imported case of Lassa in 2007 in a patient who was sent from Nigeria to Gauteng for treatment. Fortunately, the possibility of Lassa was considered very quickly and appropriate infection control precautions were taken rapidly to prevent any spread within the hospital setting to health workers,” said Prof Blumberg. She added that rapid recognition of possible cases of any VHF is key in preventing spread. “The NICD has a specialised high security laboratory where testing can be done for a range of these viruses including Lassa Fever. Overall the commonest cause of fever in patients or travellers from Africa remains malaria. Any acute fever with flu-like symptoms is more likely to be due to malaria rather than Lassa,” added Prof Blumberg. She said travellers should be aware of the importance of preventing malaria. People who have malaria need urgent testing and treatment as malaria progresses rapidly to complicated disease. Measures in place to detect Lassa Fever Measures put in place to detect Lassa Fever and other VHFs in South Africa according to Prof Blumberg include training of health workers to ask patients for a detailed travel history and possible exposures, provision of specialised lab tests, protective measures for health workers, asking detailed histories regarding occupation and possible exposures to rodents, ticks, mosquitoes and animals. Dr Robyn Holgate, the Chief Medical Officer at ER24, said ER24 continues to screen all patients for a travel history to West Africa. “It’s critical we detect a potential VHF case before transfer or admission to hospital. Basic appropriate personal protective equipment is mandatory at ER24, and we have an escalation process which addresses any clinical concerns after history and examination,” she said. Dr Holgate said there is no need for South Africans to be alarmed. “We live in a global environment. South Africa receives regular visitors from West Africa, including healthcare workers, asylum seekers and business travellers and there is no current need for us to panic. The virus is not airborne and it is not transmitted by insects such as mosquitoes,” she said. Dr Holgate recommends that non-essential business travel to affected areas be avoided as a precautionary measure. Visitors to affected countries are advised to avoid contact with rats as well as to ensure that food eaten is stored in rodent-proof containers. Proper hygiene is vital. You should ensure that your hands are washed thoroughly.