View all frequently asked questions
Ebola virus disease (EVD) was previously known as Ebola haemorrhagic fever. It is a severe, often fatal disease in humans and nonhuman primates (monkeys, gorillas and chimpanzees).
EVD is caused by a virus, and first appeared in 1976 when two outbreaks (o ne in an area near the Ebola River in Democratic Republic of Congo, and the other in South Sud an) occurred. Since then, sporadic outbreaks have occurred, most commonly in the Democratic Republic of Congo, Uganda, South Sudan, Congo and Gabon.
The origin of Ebola virus is not known, but fruit bats are thought to be the likely host of the virus.
Ebola virus is thought to be transmitted to humans through direct contact with the blood, secretions, organs or other bodily fluids of infected animals (which include: chimpanzees, gorillas, bats, monkeys, forest antelope and porcupines). This occurs when hunters/ other persons come into contact with infected dead animals found lying in the rainforest, or handling raw meat of infected animals.
Once a person is infected, the Ebola virus can spread to other people in the community.
Infection occurs from direct contact (through broken skin or mucous membranes, including the nose, eyes and mouth) with blood, or other bodily fluids and secretions (including stool, urine, saliva, semen) of infected people. Less commonly, infection can also occur from direct contact (through broken skin, or mucous membranes –including the nose, eyes and mouth) with environments that are contaminated with an Ebola patient’s infectious blood or body fluids, such as soiled clothing, bed linen, or used needles. Burial ceremonies in which mourners have direct contact with the body of the deceased person have also been responsible for spreading infection in some outbreaks. Ebola virus is not spread in the air, so simply being in the same room as an infected person without having the kinds of contact detailed above is not a risk for infection.
During EVD outbreaks, the following persons are most at risk for infection:
After infection with the Ebola virus, there is an incubation period of 2 – 21 days (on average, 8-10 days) after which the person will start to experience symptoms. During the incubation period, the person is well and shows no signs of being infected. After the incubation period, the initial symptoms include fever, weakness and lethargy, muscle pain, headache and sometimes sore throat. This is followed by vomiting, diarrhoea, abdominal pain, and sometimes a rash. Some patients may experience bleeding inside and outside of the body; this is the most serious complication.
EVD can only be confirmed through laboratory testing, usually a blood test. A specialised laboratory at the National Institute for Communicable Diseases in Johannesburg is able to test for Ebola virus disease. EVD can only be diagnosed once a person develops signs and symptoms of the disease; there is no test available to detect infection whilst a person is still in the incubation period of disease.
There is no medication available to treat the Ebola virus itself. Standard treatment for EVD is limited to supportive therapy, and severely ill patients require intensive supportive care. This consists of balancing the patient’s fluids and electrolytes, maintaining their oxygen status and blood pressure, and treating them early for any complicating infections.
Some patients will recover with the appropriate medical care. In previous EVD outbreaks, 50-90% of Ebola patients have died. In the current EVD outbreak in West Africa, about 60% of Ebola patients have died.
To control further spread of Ebola virus, patients that are suspected to have EVD should be isolated from other patients and treated by healthcare workers using very strict precautions to prevent being infected.
Experimental treatment has been tested in animal models, but has not yet been used in humans.
There is no licensed vaccine for EVD. Several vaccines are being tested, but none are available for clinical use as yet. Preventing initial cases is challenging, since it is still not known how exactly Ebola virus is maintained in nature and what preventive interventions would be successful.
Once an initial case of EVD occurs in a community, preventing spread to other people is critical. This includes educating the general public about the disease and how it can be prevented from spreading further.
Healthcare workers are at high risk of exposure to the virus when caring for Ebola patients, and need to apply additional infection control precautions over and above the standard healthcare precautions. This includes wearing personal protective equipment (including gloves, masks, gowns and goggles), ensuring complete equipment sterilisation, and the routine use of disinfectant. Infected patients must be isolated from other patients and cared for by staff who are trained in the appropriate infection control measures.
The World Health Organization regularly reviews the public health situation and recommends any travel or trade restrictions. At present, no travel or trade restrictions are recommended.
The risk of infection for travellers is very low, even if the visit included travel to the local areas from which primary cases have been reported. Infection with Ebola virus requires direct contact with blood, secretions, organs or other body fluids of infected living or dead persons or animals, all of which are unlikely exposures for the average traveller.
There is no risk of Ebola virus transmission during the incubation period and only low risk of transmission in the early phase of disease. Historically, several cases of haemorrhagic fever (Ebola, Marburg, Lassa, Crimean‐Congo haemorrhagic fever) disease were diagnosed after long‐ distance travel but none developed the symptoms during the international travel and no persons who came into contact with the patients during travel were infected.
What precautions should be taken if travelling to West African countries currently experiencing the EVD outbreak?
Travellers must have a valid yellow fever vaccination certificate when travelling to Guinea, Liberia, or Sierra Leone.
Since these countries are risk areas for malaria, travellers should consult a healthcare professional regarding the appropriate malaria prophylaxis that needs to be taken. Malaria is the most likely cause of illness with fever in a person who has travelled to West Africa, so travellers must pay particular attention to malaria prevention.
The symptoms of early EVD are the same as many other infections that can be acquired in West Africa, including malaria, dengue fever, Lassa fever, and typhoid fever. Travellers should take routine precautions to prevent such infections, including: malaria prophylaxis, preventing mosquito bites, regular hand washing with clean water and soap, and adhering to safe water and food practices.
Yes – there has been one imported case of EVD documented in South Africa. In 1996, a Gabonese doctor working with EVD patients in Libreville, Gabon, was admitted to a hospital in Johannesburg. A nurse caring for the patient became infected and died.
EVD cases have been reported from the capital cities of Conakry, Monrovia and Freetown during the current outbreak; given the frequency of travel between southern and western African countries, there is a risk of EVD cases being imported into South Africa, but this risk is thought to be low.
In the current EVD outbreak in West Africa, there has been only one case of imported EVD to date, reported from Nigeria. A 40‐year‐old Liberian male national who travelled by air on 20 July 2014 to Nigeria via Togo and Ghana was admitted to a Lagos hospital with symptoms of EVD and died a few days later. No further suspected cases have been reported in connection with this patient.
There have been no cases of EVD in South Africa associated with this outbreak.
The World Health Organization has issued recommendations for public health authorities and transport sectors with regards travel and transport risk assessments during the current EVD outbreak. Routine screening of all passengers at points of entry is not recommended.
South African Port Health authorities are on high alert for ill persons with EVD‐compatible symptoms who have travelled from West Africa. An alert for healthcare workers is available on the NICD website (www.nicd.ac.za) and is updated regularly; this alert includes recommendations for assessing ill persons who have travelled to West Africa.
FAQs complied by John Frean, National Institute for Communicable Diseases, Johannesburg, South Africa.
Schistosomiasis is a disease caused by parasitic worms (called flukes) that live in the blood vessels of the bladder and reproductive organs, and the large intestine. There are 2 forms of the disease: urinary schisto, caused by Schistosoma haematobium, and intestinal schisto, caused by S. mansoni. You get the infection by swimming or wading in water containing the infective cercarial stages, which are released from infected water snails. The snails become infected from humans with schisto, who have contaminated soil and water with urine and faeces containing eggs; these hatch in contact with water and release a larval stage that targets the snails.
Schisto is a major public health problem in South Africa; there are about 4 million people, mainly children, infected or at risk. The map shows the geographic distribution in South Africa; all other sub-Saharan African countries are affected to various extents, and visitors should assume all rivers, lakes and dams are infected. Malawi is a particularly common infection risk area for tourists, because of the major attraction of the lake and water-related recreation.
Schisto distribution in southern Africa (by kind permission of Prof Peter Fripp)
The female flukes lay eggs that cause inflammatory damage to internal organs – mainly lower colon and rectum, bladder and liver, but also sometimes the lungs, reproductive organs, and occasionally the brain and spinal cord. The amount of tissue damage is related to the intensity of infection. Visitors exposed to heavy infections for the first time are more likely to get an itchy skin rash followed a few weeks later by an acute, sometimes severe, feverish illness called ‘Katayama fever’. This is uncommon, and most patients only seek medical advice many weeks or months after exposure. Light infections may produce no illness at all. Early symptoms are often non-specific and may only be a general sense of unwellness, fatigue, or fever, but passing blood in urine is the classic sign of urinary schisto; intestinal infection may present with diarrhoea and less commonly, bloody stools. Long-term complications of schisto (after years or decades of infection) include kidney and liver disease, bladder cancer, and infertility.
The earliest sign (3 to 6 weeks after infection) is usually a raised number of certain white blood cells, called eosinophils, followed by the appearance of antibodies (around 4 weeks); finally eggs appear 5 to 15 weeks after exposure, accompanied by blood, which may not be visible to the eye and only be detectable by urine dipstick or microscopy. The ‘first prize’ in the diagnosis of schisto is finding eggs in urine or faeces, but they are often not found in early and/or light infections; tissue biopsies are more sensitive, but not often done. There is a rapid urine antigen test, but the present commercial version is not very sensitive for urinary schisto; a better type is in a late stage of development and in future will greatly simplify the diagnosis.
Infections are often asymptomatic, so if there has been water exposure in a schisto risk area, it may be sensible to do an antibody test 3 months later, and look for eggs if it is positive. If a person has been diagnosed and treated previously, then blood tests are of little use. Symptomatic patients may require repeated lab tests until the diagnosis is confirmed or an alternative explanation for illness is found.
The treatment for schisto is praziquantel (Biltricide, Bayer). It is effective against both types of schisto. The side effects of praziquantel are usually mild (nausea, abdominal discomfort, headache, dizziness), and minimised by taking it with food. Praziquantel is only 60% to 90% effective when taken in the early stage of infection and therefore some patients will require re-treatment.
Eggs may be excreted for a while even after successful treatment, so their mere presence does not necessarily indicate treatment failure; a laboratory report on the viability of eggs is required. Serology should not be used to monitor response to treatment, as the antibodies remain detectable for long periods afterwards.