Viral haemorrhagic fevers (VHF) are highly contagious diseases, caused by viruses from four distinct families. They range in severity from relatively mild to life-threatening. Although all begin with fever and muscle aches, some VHFs progress to far more serious problems, including severe internal and external bleeding (haemorrhage), widespread tissue death (necrosis), and shock.
The origin of the two deadliest VHFs — ebola and marburg viruses — isn’t known, but the viruses that cause other haemorrhagic fevers are transmitted to humans by animals or insects, primarily rodents, mosquitoes or ticks. In some, but not all cases, the virus can then spread from person to person through contact with infected blood or body fluids, including semen. Secondary transmission can also occur through contaminated needles and syringes, a particular problem in the developing countries where medical equipment is in short supply and may be reused.
Haemorrhagic fevers make blood vessels more permeable, that is, more likely to leak, causing bleeding that can range from relatively minor to massive. Bleeding may occur under your skin, in internal organs, and from your mouth, eyes, ears and rectum. People with severe bleeding may experience potentially lethal symptoms such as shock and coma, but rarely die of blood loss.
There are certain kinds of fevers that are highly contagious and need an immediate check-up
In general, signs and symptoms of most VHFs begin two days to three weeks after you’ve been exposed to the virus. All begin with fever and muscle aches; many cause vomiting and diarrhoea; and all create problems in a number of organ systems, especially your liver, lymphatic system, lungs and sometimes your kidneys.
The four families of viruses that cause VHFs are discussed here.
Arenaviruses: This viral family includes Lassa fever, Argentine haemorrhagic fever, Bolivian haemorrhagic fever, Brazilian haemorrhagic fever and Venezuelan haemorrhagic fever. If you’ve been exposed to one of these illnesses, you’re likely to experience some of the following signs and symptoms:
• Fever, which may be constant or intermittent
• Pain behind your chest wall and in your back
• A sore and inflamed throat with white patches on your tonsils
• Cough
• Abdominal pain
• Vomiting
• Diarrhoea
• Conjunctivitis, an inflammation of the transparent membrane (conjunctiva) that covers your eyelids and part of your eyeballs
• Bleeding from your gums or in your stomach, small intestine and other internal organs, facial swelling
• Temporary or permanent hearing loss
• Fluid in your lungs (pleural effusion)
• Encephalitis, a life-threatening inflammation of the brain
Bunyaviruses: Included in this group of VHFs are Rift valley fever, Crimean-Congo haemorrhagic fever, haemorrhagic fever with renal syndrome and hantavirus pulmonary syndrome.
In the case of Crimean-Congo haemorrhagic fever (CCHF) it is an endemic tick-borne viral disease whose wide geographical distribution includes the cold, arid regions of Pakistan. The virus replicates in its natural hosts which include goats, sheep, cattle and camels.
Humans are infected by the body fluids of infected animals or other humans. Contacted with the blood of infected tick can also result in infection among human.
In the case of hantavirus pulmonary syndrome, abnormally low blood pressure (hypotension) and difficulty in breathing possibly lead to respiratory failure. From 1976 to 2000 Pakistan faced different outbreaks of the CCHF in its different parts including Rawalpindi, Balochistan, Quetta, Kohlu, Peshawar, Sibi, Lucky Marwat, Loaralai, and Karachi.
Filoviruses: This viral family consists of the ebola and marburg viruses, which are among the most virulent of all known diseases. Signs and symptoms appear within two days to three weeks of infection and initially include those common to other VHFs: fever, intense weakness, muscle pain, vomiting and diarrhoea. As the disease progresses, some people also develop: * A distinctive, haemorrhagic rash * Bleeding from the nose, mouth, eyes, ears and rectum * Seizures * Coma * Delirium
Flaviviruses: This group includes yellow fever, dengue fever, dengue haemorrhagic fever, Kyasanur Forest disease and Omsk haemorrhagic fever. Yellow fever and dengue fever are probably the most well-known VHFs. Dengue is a major public health concern, with 50 million to 100 million cases a year worldwide, including major epidemics at popular tourist destinations.
Signs and symptoms of dengue fever vary with age. Infants and young children usually develop a rash and severe, flu-like symptoms, whereas older children and adults may experience a high fever, severe headache, eye pain, muscle aches and rash. In the haemorrhagic form, an extremely high fever may be accompanied by bleeding, convulsions and circulatory failure.
Causes: Emerging diseases are infections that are appearing for the first time or that are rapidly increasing in incidence and range. Many of these infections have surfaced in the past several decades, including VHFs such as ebola and hantavirus pulmonary syndrome and illnesses such as HIV/Aids, lyme disease and Sars.
The virus that causes hantavirus pulmonary syndrome spreads to humans through contact with the infected droppings, urine or saliva of deer mice. Non-human primates such as monkeys, chimpanzees and gorillas are susceptible to these diseases and can transmit them to humans.
Most of the viruses associated with the VHFs are zoonotic, which means they reside in an animal or insect host and are dependent on that host for their survival. In general, humans acquire the virus when they come into contact with an infected host, but in some cases, person-to-person transmission can occur after the initial infection. Human epidemics occur sporadically, usually because of a combination of climatic, ecological and social factors.
Risk factors: The chance of contracting most VHFs is low. Some are confined to isolated pockets in remote areas where the risk of transmission is slight. And because each virus is usually associated with a specific host species, it’s normally restricted to the area where that species lives.
Yet taken together, the viruses that cause VHFs occur over most of the world. And some VHFs, especially Lassa, yellow and dengue haemorrhagic fevers, pose a real threat to people travelling to or living in the regions where these diseases are widespread, primarily sub-Saharan Africa and South America.
In general, your risk of contracting any disease abroad depends on your itinerary and activities, the length of your stay and the rate of transmission of a particular disease at the time. If you’re visiting a region for a week or two, staying in westernized hotels and taking guided tours, your risk is less than if you’re travelling for months and living in a tent. Still, you’re at risk of epidemic diseases such as dengue fever even in the best of circumstances, although your risk decreases if there are no outbreaks of the disease during your visit.
Screening and diagnosis: Diagnosing specific VHFs in the first few days of illness can be difficult. All infected people initially exhibit the same signs and symptoms. What’s more, these signs and symptoms frequently occur with many diseases that are far more common than the VHFs.
To reach an accurate diagnosis, your doctor is likely to ask about your medical and travel history and any exposure to rodents or mosquitoes. Be sure to describe international trips in detail, including the countries you visited and the dates, as well as any contact you may have had with possible sources of infection.
Laboratory tests, usually using a sample of your blood, are needed to confirm a diagnosis of the VHF. Because VHF viruses are particularly virulent and contagious, these tests are usually performed in specially designated laboratories using strict precautions.
Complications: Although complications of the VHFs vary, some problems occur with many of the viruses. They include:
Uveitis. This eye inflammation affects the uvea, the layer just beneath the white of your eye (sclera). Uveitis causes redness, pain and sensitivity to light. Though it’s serious, it rarely leads to permanent blindness if not treated promptly and appropriately.
Pericarditis. This is swelling and irritation of the pericardium, the thin, membranous sac that surrounds your heart. Pericarditis usually causes sharp, stabbing chest pain, shortness of breath and an overall feeling of weakness or fatigue.
Encephalitis. This severe, potentially life-threatening brain inflammation may occur on its own or follow another viral infection. Severe encephalitis can cause respiratory arrest, marked mental impairment, coma and death.
Orchitis. This acute inflammation of the testicles causes swelling and pain and usually occurs as a result of a viral infection. In some cases, orchitis can lead to infertility, but it rarely leaves a man sterile.
Spontaneous abortion. Loss of an unborn child is a frequent complication in pregnant women who develop VHFs.
Hair loss. Many people who recover from VHFs experience temporary or permanent hair loss.
Treatment: No specific treatment exists for most VHFs, although the antiviral drug ribavirin may help shorten the course of infection and prevent complications in arenaviruses and bunyaviruses. Whether bleeding complications should be treated with therapies such as clotting factors, platelets and heparin remains a matter of debate.
Supportive care is essential for every person having VHF, no matter what type of virus is involved. This is likely to include measures to:
Provide adequate fluids and maintain the balance of electrolytes — substances such as sodium, potassium, chloride and calcium, which control the movement of nutrients into cells
Prevention. Preventing the VHFs, especially in developing nations, presents enormous challenges. Many of the social, economic and ecological factors that contribute to the sudden appearance and spread of infectious diseases. For that reason, the best approach in the short-term is to take precautions to protect yourself from infection:
Get vaccinated. Vaccines exist for yellow fever and Argentine haemorrhagic fever. If you’re travelling to areas where these diseases are endemic, consider being vaccinated. The yellow fever vaccine is generally considered safe and effective, although in rare cases, serious side effects can occur. The yellow fever vaccine isn’t recommended for children under nine months of age or for pregnant women, especially during the first trimester.
Be sure you’re mosquito-proof. Such as wearing light-coloured long pants and long-sleeved shirts or better yet. Avoid unnecessary activities at dusk and dawn when mosquitoes are most active and apply mosquito repellent. If you’re sleeping in open place or local hotels, use bed nets and mosquito coils.
Dr Aftab Ahmed Khan
