WHO Priority Diseases: Disease X

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WHO has added a new, yet unknown disease, calling it ‘Disease X’, in its list of eight priority diseases, which pose a public health risk due to their epidemic potential and for which there are no drugs or vaccine to treat them or prevent them. And there is an urgent need for research into these diseases for better diagnostic methods, improved vaccines and treatment.

“Disease X represents the knowledge that a serious international epidemic could be caused by a pathogen currently unknown to cause human disease, and so the R&D Blueprint explicitly seeks to enable cross-cutting R&D preparedness that is also relevant for an unknown “Disease X” as far as possible,” says the WHO.

It is believed that the next big global epidemic could be even deadlier than the presently known diseases such as Ebola. Just as the pathogen is unknown, so is its probable source. But, it is presumed that it will most likely be a zoonotic disease, with animals as the source of infection. And, modern travel and transportation will only facilitate rapid spread of the infection so that it becomes a global threat. Mutations can change the existing viruses into genetically new virus types. Then lab-mutated viruses or creation of new viruses in labs can also be a likely source. We don’t know. These are only speculations.

Urbanization is a public health risk. Newer townships are coming up rapidly or cities are being expanded. The cost of urbanization is deforestation. This means that we are encroaching further into an ecosystem that was previously undisturbed by humans. The resulting closer contact of wild animals and humans allows unknown pathogens to be introduced into the urban areas increasing the risk of potential zoonoses and other diseases. Infectious diseases that were previously unknown or even rare are emerging and re-emerging now.

The need of the hour is to strengthen surveillance, public health care systems and research and development. A robust surveillance system to notice early, something that is unusual, not normal, is the basis of preparedness for an epidemic. Increasing public access to good health care will help in early detection of an epidemic and initiate measures to control it before it spreads further. Communication is crucial for sharing information.

The WHO has sounded a note of caution. Its up to us to be better prepared… “Forewarned is forearmed”.

Dr KK Aggarwal

Padma Shri Awardee

Vice President CMAAO

Group Editor-in-Chief IJCP Publications

President Heart Care Foundation of India

Immediate Past National President IMA

WHO Priority Diseases: SARS

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Severe acute respiratory syndrome (SARS) is a viral respiratory illness caused by a coronavirus. SARS was first reported from the Guangdong Province in China in 2002. Labelled as the first pandemic of the 21st century, SARS spread to 29 countries with more than more than 8000 cases.

Since 2003, SARS has reappeared on four counts: Three times from lab accidents (Singapore and Chinese Taipei), and once in southern China where the source of infection remains undetermined although there is circumstantial evidence of animal-to-human transmission (WHO).

SARS is caused by the SARS-associated coronavirus (SARS-CoV).
Animals eaten as exotic foods in southern China, particularly the palm civet, may be intermediate hosts.
Transmission: Humans acquire the infection from close person-to-person contact via droplet spread. The virus may also spread via contaminated surfaces or objects. Lack of or inadequate infection control precautions facilitate spread of the virus. Transmission mainly occurs during the 2nd week of illness, when the excretion of the virus in respiratory secretions and stool is at its peak.
The incubation period for SARS is 2-7 days.
Clinical presentation: A patient with SARS presents as a prodrome of high fever (>100.4°F), malaise, myalgia, headache, diarrhea, shivering followed by respiratory symptoms – cough (dry, nonproductive cough), shortness of breath. Chest x-ray may show lesion suggestive of pneumonia. Severe disease may progress to respiratory distress necessitating intensive care.
Patients are most contagious during the 2nd week of illness
Diagnosis: Polymerase chain reaction (PCR) and/or antibody detection (IgG and IgM) via ELISA (Enzyme-linked ImmunoSorbent Assay) or IFA (Immunofluorescence Assay) or virus isolation in cell cultures. Specimens include blood, stool, respiratory secretions or body tissues. A negative PCR does not exclude SARS. The samples may not have been collected at a time when the virus or its genetic material was present. PCR test must be done at the earliest and repeated if symptoms persist.
Management: Supportive care with antipyretics, oxygen supplementation (mechanical ventilation when indicated), isolation of patient, strict barrier nursing and infection control practices including personal protective equipment when in close contact with the patient. Antiviral drugs or steroids are not recommended.
(Source: WHO, CDC, Uptodate)

Dr KK Aggarwal

Padma Shri Awardee

Vice President CMAAO

Group Editor-in-Chief IJCP Publications

President Heart Care Foundation of India

Immediate Past National President IMA

WHO Priority Diseases: Rift Valley fever

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Rift Valley fever is an acute febrile illness caused by the Rift Valley fever virus, which belongs to the Bunyaviridae family, Phlebovirus genus.

Here are some key points to know about Rift Valley Fever.

The Rift Valley fever virus was first isolated in the course of an investigation into an epidemic among sheep on a farm in the Rift Valley of Kenya in 1931.
It is a viral zoonosis that mainly affects animals (usually cattle and sheep). But, humans too can acquire the infection.
Transmission of infection to humans is mainly via contact with blood or organs of infected animals through the handling of animal tissue during slaughtering or butchering, assisting with animal births, conducting veterinary procedures, or from the disposal of carcasses or fetuses.
Herders, farmers, slaughterhouse workers, and veterinarians are at greater risk of acquiring the infection.
Transmission to humans may also occur via bites from infected mosquitoes mainly Aedes and Culex.
To date, no case of human-to-human transmission of RVF virus has been documented.
Outbreaks of Rift Valley fever have been reported from sub-Saharan Africa, North Africa, following heavy rainfall, which increases the number of mosquitoes. However, in 2000, outbreaks were reported for the first time outside Africa in Saudi Arabia and Yemen. Therefore, the virus may well spread to other countries in Asia and Europe.
The incubation period is 2-6 days.
Most infected persons are either asymptomatic or have mild symptoms. The most frequently reported symptoms include fever, headache, bleeding, malaise, muscle pain, back pain, vomiting, and joint pain.
Severe disease presents as either ocular disease, meningoencephalitis or hemorrhagic fever.
The overall total case fatality rate is less than 1%. Case fatality is highest in patients with hemorrhagic fever (around 50%), which first manifests as jaundice and then with signs of hemorrhage – hematemesis, melena, purpuric rash or ecchymoses, epistaxis, menorrhagia, bleeding from gums or venepuncture sites.
Diagnosis: Detection of viral RNA by polymerase chain reaction (RT-PCR) or detection of IgM antibodies against RVF virus by enzyme-linked immunosorbent assay (ELISA) or virus isolation by cell culture. All specimens must be handled with extreme care. Standard precautions must be strictly adhered to.
Treatment: No specific treatment in mild infection; in severe cases, general supportive therapy is the main line of management.
An inactivated vaccine has been developed for human use. But it is not licensed and is not commercially available. It has been used experimentally to protect veterinary and lab personnel at high risk of exposure to RVF.
Prevention: The public must be educated about the risk factors for spread of the virus, especially in endemic areas. Gloves and other personal protective equipment must be used when handling sick animals or their tissues or slaughtering to avoid exposure to potentially infected blood or tissue. Mosquito repellents and nets should be used to protect from mosquito bites. All healthcare workers should follow standard precautions when handling specimens from patients.
(Source: Uptodate, WHO, CDC)

Dr KK Aggarwal

Padma Shri Awardee

Vice President CMAAO

Group Editor-in-Chief IJCP Publications

President Heart Care Foundation of India

Immediate Past National President IMA

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