Ross River Virus Hits Australia

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.

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California Sees Record West Nile Virus Cases in 2014

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:” 

  1. 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.
  2. 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.
  3. 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: