Viruses have different stripes – with a big difference in structure, genome organization, transmission, and replication that can infect plants, animals, humans, and organisms that are single-celled, which includes algae, microplasma and bacteria. Some viruses can only infect one host specie while others can infect several species.
Listed down below are the six most dangerous viruses that made the world on high alert in the 21st century.
1. Japanese Encephalitis Virus
Japanese Encephalitis virus is the frequent cause of the epidemic viral encephalitis across Asian countries, with 68,000 estimated as per WHO. There are 24 countries across WHO Western Pacific and Southeast Asia regions have this virus, and 3 billion individuals are at risk for the virus.
Neck rigidity, fever, headache, tremors, convulsions, and incoordination are included in the symptoms. The mortality rate is 30% high; however, survivors of 30-50% rate experienced serious psychiatric or neurologic sequelae. This disease is transmitted to humans by infected Culex species mosquitoes that live in Asian rice fields with pigs and water birds serve as its reservoir. There’s a vaccine (inactivated) that exists for humans protection against the virus. Protection for mosquitoes is recommended to those who are at high risk. Antiviral therapy is not yet available for patients that are infected; that’s why it’s treated symptomatically.
2. Marburg Virus
Both the Ebola and Marburg viruses are included in the family of filovirus. Hemorrhagic fever is one of its characteristics. The other symptoms are headache, fever, sore throat, arthralgia, vomiting, epigastric pain, and diarrhea. The Marburg virus was found out last 1967, in Germany (Marburg) by researchers, to be the reason for the illness that came from native green monkeys of Uganda. It was thought that bats are the natural reservoir for the Marburg virus; however, it was not yet confirmed. The virus’ death rate is 90% high. The patients that are infected are dying because of bleeding in the skin and gastrointestinal tract, multiorgan failure, and disseminated intravascular coagulation. There’s no vaccine and antiviral therapy for this virus.
Hantavirus (pulmonary syndrome) outbreak happened last 1993 in Arizona and New Mexico, due to Sin Nombre hantavirus. The disease, which is similar to influenza, leads to acute respiratory failure. The reservoir for Hantavirus is the deer mice, with transmission and exposure through inhalation of the reservoir’s feces or urine. It could be rare; however, it can be transferred to human via bite of a deer mice with a virus. Hikers and campers have the highest risk of having this virus. Good news! The contact of Hantavirus can’t be spread from human to human. Early symptoms are fever, muscle aches (especially in large areas) and fatigue. While late symptoms can start 4 to 10 days after the initial phase, which includes shortness of breath and coughing.
As per the CDC, the mortality rate is 38%. There’s no cure, vaccine, or treatment for the Hantavirus. Nevertheless, the survival outcomes can be improved by early recognition and by receiving medical care, which includes oxygen therapy for the presence of severe respiratory illness.
4. Lassa Fever virus
It is in Lasa Nigeria, in the year 1969, when this virus was discovered. The pathogen causes multi-organ failure and hemorrhagic fever. It has a high mortality rate of 15-50% with death because of vascular collapse. In endemic areas, asymptomatic infection is very common. It is transmitted thru exposure to urine of the Mastomys small rodent in water sources or in food. It can also be transmitted via air inhalation that’s contaminated with rodent’s secretions. Airborne transmission can occur when cleaning such as sweeping. Commonly, human to human transmission occurred in healthcare settings when there’s no proper protective equipment or when improperly used.
By giving enough Ribavirin in early stage, it can help. Moreover, a hyperimmune serum that was derived from Lassa fever survivors can also be beneficial. There’s no vaccine available for the virus; however, prevention protocol may help to control the rodent form and infection.
5. Ebola Virus
The larget outbreak of the Ebola virus happened last 2014 to 2016 in Western Africa. Are you aware that greater than 11,000 individuals died during the outbreak? Scientists have no clue where the virus came from; however, based on their hypothesis, it’s an animal-borne and most likely the source are the fruit bats. The virus carried by these bats can be transferred to another animal like primates and then spreading to humans. The transmission and exposure from human to human is possible through direct contact with body fluids.
There might be a sudden onset of symptoms that includes fatigue, fever, headache, muscle pain, vomiting, sore throat, rash, diarrhea, external and internal bleeding, and impaired liver and kidney function. As per the WHO (World Health Organization), the fatality rate has an average of 50%. Since there is no proven treatment yet, treatment of symptoms and supportive care like rehydration with intravenous fluids or oral are given to increase the survival rate. However, for some, there are experimental treatments being administered and that includes antibody treatment and convalescent serum. Moreover, the combined research effort to develop a vaccine is ongoing.
If untreated, rabies is 100% fatal. It can be found in 150 territories or more. Generally, the incubation stage is 2 to 3 months, with symptoms that start with paresthesia on the bite, prickling, and fever including pain. As it progresses to the central nervous system, deadly inflammation of the spinal cord and brain develops.
Two forms of rabies that infect humans may develop: paralytic rabies and furious rabies. As per WHO, furious rabies symptoms include excitable behavior, hyperactivity signs, aerophobia, hydrophobia and death due to the arrest of cardio and respiratory, a few days after. On the other hand, in paralytic rabies, it progressively becomes paralyzed, which starts from the bite area. Coma then follows and, eventually, death.
Dog bites are well known to be the cause of rabies infection, and bats are next. A rabies shot is given after being bitten and it can be curative. Moreover, washing the wound with soap and water is very important when bitten by the rabid animal as the infection occurs the moment the mucous membrane is exposed to saliva.
The list above is scary; however, there’s still hope that those viruses above will be gone someday. Smallpox is one example. After numerous decades, in the year 1970s, a vaccine was discovered and helped eradicate it.
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