One of my modern day medical idols is Dr. Anthony Fauci, one of the lead editors of the two-volume Bible of Internal Medicine, “Harrison’s Internal Medicine”, and also the Director of the National Institute of Allergy and Infectious Diseases. In an NIH News piece he has commented:
“The Ebola virus in the ongoing West African outbreak appears to be stable—that is, it does not appear to be mutating more rapidly than viruses in previous Ebola outbreaks, and that is reassuring,”…. “We look forward to additional information to validate this finding, because understanding and tracking Ebola virus evolution are critical to ensuring that our scientific and public health response keeps pace.”
This news article presents good news in context of the proportions that the Ebola outbreak has assumed in the Western African countries, accounting for 25,000 odd cases and about 10,000 deaths.
According to a recent article published in the New England Journal of Medicine, a novel zoonotic orthopoxvirus caused lesions in two men in the country of Georgia. Another sample, tested retrospectively after being stored for suspected Anthrax, also turned out to be positive for this new pox virus.
The article abstract states:
During 2013, cutaneous lesions developed in two men in the country of Georgia after they were exposed to ill cows. The men had never received vaccination against smallpox. Tests of lesion material with the use of a quantitative real-time polymerase-chain-reaction assay for non–variola virus orthopoxviruses were positive, and DNA sequence analysis implicated a novel orthopoxvirus species. During the ensuing epidemiologic investigation, no additional human cases were identified. However, serologic evidence of exposure to an orthopoxvirus was detected in cows in the patients’ herd and in captured rodents and shrews. A third case of human infection that occurred in 2010 was diagnosed retrospectively during testing of archived specimens that were originally submitted for tests to detect anthrax. Orthopoxvirus infection should be considered in persons in whom cutaneous lesions develop after contact with animals.
Vora NM, Li Y, Geleishvili M, et al: Human infection with a zoonotic orthopoxvirus in the country of Georgia. N Engl J Med. 2015;372(13): 1223-30. doi: 10.1056/NEJMoa1407647. Available from: LINK.
Ross River Virus (RRV), a zoonotic alpha virus, is spread by a wide range of mosquitoes, including the Culex and Aedes mosquitoes. Queensland seems to be the worst hit with this disease, with as many as 3292 cases being reported till the end of March 2015. New South Wales has also seen a surge in the number of RRV cases as over 320 cases were registered by the middle of March 2015. It has rapidly emerged to be the most important vector borne disease in Australis, as far as number of cases are concerned, with over 5000 cases being consistently reported annually.
RRV causes a disease which is rarely fatal and manifests primarily as acute polyarthralgia. However, the pain in the joints, which can sometimes be debilitating, may persist for weeks after the acute phase of the disease is over. This was the basis for its previous nomenclature, epidemic polyarthritis.
RRV transmission to human beings is associated with the rainy season, when there is an abundance of breeding opportunities for mosquitoes. The main methods to stave off the disease encompasses methods of vector control and vector avoidance.
The virus is named after the Ross river in Townsville, where it was first identified to be the causative organism behind the epidemic polyarthritis.
According to a (translated) report in Free News Volga, the Saratov regions remains active for the transmission of Hemorrhagic Fever with Renal Syndrome (HFRS). In January 2015, as many as 121 people were identified to be suffering from HFRS, which represents a four fold increment to the number of cases reported in January 2014.
HFRS is a group of symptomatologically similar diseases caused by a group of viruses belonging to the family Bunyaviridae. The viruses that cause HFRS include Hantaan, Dobrava, Saaremaa, Seoul and Puumala viruses.
These viruses are primarily carried by rodents and human beings get affected when they come in contact with rodent urine or saliva or even aerosolized dust from rodent nests. Known carriers
include the striped field mouse (Apodemus agrarius), the reservoir for both the Saaremaa and Hantaan virus; the brown or Norway rat (Rattus norvegicus), the reservoir for Seoul virus; the bank vole (Clethrionomys glareolus), the reservoir for Puumala virus; and the yellow-necked field mouse (Apodemus flavicollis), which carries the Dobrava virus.
Control measures, therefore, center around measures for rodent control and exposure limitation. None of the HFRS have a specific treatment and supportive therapy, with maintenance of hydration, electrolytes, appropriate antibiotics to treat any secondary infections and dialysis for renal support being the pillars of disease management. Depending on the causative virus and the patient profile, mortality varies from as low as 1% to as high as 15%.
Two more counties in Wisconsin have fallen prey to the Highly Pathogenic Avian Influenza H5N2 strain which continues its exponential race across the Mississippi flyway, along which this infection has been gaining momentum. According to the report in Madison, this new outbreak, affecting the Barron and Juneau counties, have put almost 126,000 heads of poultry at risk.
Although this disease seems to be highly infectious and has a very high case fatality rate, it has not yet made the species jump at similar proportions and is believed to be of little infectivity and virulence to man.
According to the report of the Bangladesh Institute of Epidemiology, Disease Control and Research, there have been 9 cases of Nipah virus encephalitis in the country in the first two months of 2015. Of these 9 cases, 6 have died, attributing a 67% mortality to the disease in the current year.
The consumption of fruit and fruit products, primarily date and date palm sap, contaminated with the urine or saliva of infected fruit bats is the main reason behind the disease. Fruit bats, belonging to the Pteropodidae family (Pteropus giganteus) are the most commonly implicated in the transmission of this virus which has a very high case fatality rate. The CFR varies from 40-75% depending on different outbreak areas, and the immediacy of diagnosis and management initiation, which may be a major cause of delay.
Unfortunately, there is no vaccine or specific treatment for this disease and most cases need intense supportive care. The virus emerged first in a cluster of cases in Malaysia, but has been established in Bangladesh, which is currently the only country reporting cases of Nipah virus disease.
|Pteropus giganteus Image Credits: Wikimedia
For the week ending 16th April, 2015:
The recent report by the California Department of Public Health clearly indicates that the West Nile Virus is reaching greater proportion with every passing year. The Press Release of the CDPH on this issue states:
California had the second-highest number of human cases of West Nile virus (WNV) in 2014 since the virus first invaded California in 2003. In 2014, California recorded 801 cases of the potentially fatal disease. In 2005, CDPH detected 880 cases of WNV.The highest number of cases was in Orange County (263 cases) and the highest incidence occurred in Glenn County (35.3 cases per 100,000 population).
The level of WNV activity last year broke several records including:
- Five-hundred-sixty-one cases of West Nile neuroinvasive disease (WNND), the more serious neurological form of the disease often resulting in encephalitis or meningitis, were detected.
- The number of fatal WNV cases, 31, exceeded all previous years.
- The proportion of mosquitoes infected with WNV was the highest level ever detected in California (mosquito infection rate = 6.0; epidemic conditions equate with 5.0).
- The prevalence of WNV infection in tested dead birds, 60 percent, was the highest ever detected in California.
CDPH recommends that individuals prevent exposure to mosquito bites and West Nile virus by practicing the “Three Ds:”
- DEET- Apply insect repellent containing DEET, picaradin, oil of lemon eucalyptus, or IR3535 according to label instructions. Repellents keep the mosquitoes from biting you. DEET can be used safely on infants and children 2 months of age and older.
- DAWN AND DUSK – Mosquitoes bite in the early morning and evening so it is important to wear protective clothing and repellent if you are outside during these times. Make sure that your doors and windows have tight-fitting screens to keep out mosquitoes. Repair or replace screens with tears or holes.
- DRAIN – Mosquitoes lay their eggs on standing water. Eliminate all sources of standing water on your property, including in flower pots, old car tires and buckets. If you know of a swimming pool that is not being properly maintained, please contact your local mosquito and vector control agency.
A brief summary of the outbreak statistics from 2003:
Yellow fever vaccine is recommended to all travelers who are planning a trip to countries endemic for the disease. The vaccine is relatively safe and effective and recently, there have been two isolated reports of a fatal and extremely rare complication arising from the YF vaccine, the Yellow Fever Vaccine associated Viscerotropic Disease (YEL-AVD). The CDC MMWR reported a case in Oregon, USA, and the Outbreak News Blog reported a case from Hong Kong.
YEL-AVD results from the uncontrolled replication of the vaccine virus, finally leading to multi-organ failure and has a reported mortality to the tune of 60%.
FIGURE from CDC Report: Yellow fever virus antigens (red) detected after immunohistochemical staining in tissue samples from various organs* of a patient who died from yellow fever vaccine–associated viscerotropic disease — Oregon, September 2014
* Sample A: myocytes in heart; sample B: fibroblasts in vascular wall in lung; sample C: kupffer cell in liver; sample D: fibroblasts and histiocytes in skin. (Immunoalkaline phosphatase with naphthol fast-red substrate and hematoxylin counterstain. Original magnifications: A = x400; B = x100; C = x400; D = x100.)
The CDC report further states that the risk of YEL-AVD is 0.4 per 100,000 doses of YF vaccine administered. The risk is increases with age: in patients older than 60 years it has a risk of 1/100,000 doses while those that, those who are older than 70 years have a risk of 2.3/100,000 doses administered. Almost a quarter of the first few cases of YEL-AVD that have been reported had a history of thymoma and it is estimated that the increased risk attributable to thyme disease persists even after thyme resection.