Ebola virus disease: A Global threat

RESERVOR:

The natural reservoir for Ebola has yet to be confirmed; however, bats are considered to be the most likely candidate species.⁽²⁾ Three types of fruit bats (Hypsignathus monstrosus, Epomops franqueti and Myonycteris torquata) were found to possibly carry the virus without getting sick.⁽³⁾ Plants, arthropods and birds have also been considered possible viral reservoirs.⁽¹⁾

TRANSMISSION:

Between people, Ebola disease spreads only by direct contact with the blood or body fluids of a person who has developed symptoms of the disease. Body fluids that may contain ebolaviruses include saliva, mucus, vomit, feces, sweat, tears, breast milk, urine and semen.

Ebola may be spread through large droplets; however this is believed to occur only when a preson is very sick. The Ebola virus may be able to persist for up to 7 weeks in the semen of survivors after they recovered, which could lead to infections via sexual intercourse.⁽¹⁾ Ebola may also occur in the breast milk of women after recovery, and it is not known when it is safe to breastfeed again⁽⁴⁾. Otherwise, people who have recovered are not infectious.

Airborne Transmission: Human to human transmission of EBOLA through the air has not been reported to occur during Ebola outbreaks and airborne transmission has only been demonstrated in very laboratory conditions, then only from pigs to primates but not from primates to primates. Spread of Ebola by water or food, other than bush meat, has also not been observed. No spread by mosquitos or other insects has been reported. ⁽⁵⁾

SIGN & SYMPTOMS:

The length of time between exposure to the virus and the development of symptoms of the disease is usually 2 to 21 days. Symptoms usually begin with a sudden influenza-like stage characterized by feeling tired, fever, pain in the muscles and joints, headache, and sore throat.^(1,6,7) The fever is usually higher than 38.3 °C (100.9 °F).⁽⁸⁾ This is often followed by vomiting, diarrhea and abdominal pain. Next, shortness of breath and chest pain may occur, along with swelling, headaches and confusion.⁽⁷⁾ In about half of the cases, the skin may develop a maculopapular rash (a flat red area covered with small bumps).⁽⁸⁾

In some cases, bleeding manifestation may started 5 -7 days after the first symptom like vomiting of blood, coughing up of blood, or blood in stool. Bleeding into the skin may create petechiae, ecchymoses or hematomas, but heavy bleeding is uncommon, if it occurs, it is usually located in gastrointestinal tract. Recovery may begin between 7 and 14 after the start of symptom. Death, if it occurs, follows typically 6-16 days from the start of symptom. Those who survive often have ongoing muscle & joint pain, liver inflammation & decreased hearing among other difficulties. They developed antibodies against Ebola that last at least 10 years, but it is unclear, if they are immune to repeated infections. If someone survives Ebola, they can no longer transmit disease.⁽⁶⁾

DIAGNOSIS:

Nonspecific laboratory testing Possible laboratory indicators of EVD include a low platelet count; an initially decreased white blood cell count followed by an increased white blood cell count; elevated levels of the liver enzymes alanine aminotransferase (ALT) and aspartate aminotransferase (AST); and abnormalities in blood clotting often consistent with disseminated intravascular coagulation(DIC) such as a prolonged prothrombin time, partial thromboplastin time, and bleeding time.⁽⁹⁾

Specific laboratory testing

The diagnosis of EVD is confirmed by isolating the virus, detecting its RNA or proteins, or detecting antibodies against the virus in a person's blood. Isolating the virus by cell culture, detecting the viral RNA by polymerase chain reaction (PCR) and detecting proteins by enzyme-linked immunosorbent assay (ELISA) are methods best used in the early stages of the disease and also for detecting the virus in human remains. Detecting antibodies against the virus is most reliable in the later stages of the disease and in those who recover.⁽¹⁰⁾