West Nile Virus: Case Update

As of 8/20,2018, ODH is reporting 5 human West Nile virus (WNV) cases, including 1 fatality, and 2 asymptomatic WNV viremic blood donors in Ohio.  Additionally, ODH received a report today from the Ohio Department of Agriculture of an equine case in an unvaccinated horse.  WNV activity in mosquitoes continues to rise and we have now seen indications of virus activity in 52 Ohio counties so far this year.

The graph below shows where we are this year with infection rates in mosquitoes compared to 2012, a high WNV activity year (red dotted line), and 2016, a relatively normal WNV activity year (green dashed line):

In addition to WNV, ODH is also reporting 6 LAC cases and 2 unspecified California virus cases.  The rainfall we’ve had this summer has continuously filled tree holes and containers with water, creating ideal conditions for tree hole mosquitoes (vectors of LAC virus) to breed. For more information about arbovirus cases and surveillance data, see the current Ohio arbovirus surveillance update at http://www.odh.ohio.gov/arboupdate, updated earlier today.

There are quite a few weeks left in this  mosquito season and cases can occur into October, so it is very important to continue your community and public education efforts focusing on personal protection and source reduction. Also, please call the Zoonotic Disease Program (ZDP) at (614) 752-1029 if you have any questions.

A New Tick Species Found in the United States

You probably have heard about this new tick invasive in the U.S. First detected in late 2017 in NJ. Recent reports are that it is spreading rapidly. See news clips as below:

“For the first time in 50 years, a new tick species has arrived in the United States — one that in its Asian home range carries fearsome diseases.

The Asian long-horned tick, Haemaphysalis longicornis, is spreading rapidly along the Eastern Seaboard. It has been found in seven states and in the heavily populated suburbs of New York City.

For now, the new arrivals are considered a greater threat to livestock.

Known in Australia as bush ticks and in New Zealand as cattle ticks, long-horned ticks can multiply rapidly and suck so much blood from a young animal that it dies.

The longhorn tick is known to carry several diseases that infect hogs and cattle in Asia. So far, ticks examined in the U.S. do not carry any diseases that can infect humans, but the USDA says the insects frequently form large infestations that cause great stress on warm-blooded host animals, reducing its growth and production. A severe infestation can kill the animal due to blood loss.

 

Officials said female longhorn ticks reproduce asexually and a single tick can reproduce and lay 2,000 eggs after feeding on a host. Cattle, pets, small mammals, birds and humans are all potential hosts.

 

In 2017, officials discovered the first longhorn tick population in the United States feeding on large numbers of sheep in Mercer County, New Jersey. It has also been found in Arkansas, New York, West Virginia and Virginia. Tests by the National Veterinary Services Laboratory in Ames, Iowa, have confirmed the presence of an Asian — or longhorn — tick on a wild deer in Centre County on Tuesday. It is the first confirmed sighting of the parasite in Pennsylvania.”

https://www.businessinsider.com/ticks-from-asia-that-self-clone-found-in-us-2018-2

https://www.techtimes.com/articles/227497/20180513/new-exotic-tick-species-is-spreading-in-the-us.htm

http://www.dailyitem.com/news/new-tick-species-found-in-pennsylvania/article_aed805f0-9657-11e8-ac16-4397609178cb.html

West Nile Virus Activity Continues to Increase

West Nile virus activity continues to increase and the statewide mosquito infection rate as of week 27 (week of July 4) is trending with infection rates we saw in 2012, our last epidemic year when we recorded 122 human cases.  No human cases have been reported this year yet; however, 2 asymptomatic viremic blood donors were reported this past week, so there is evidence human infections have occurred. If you haven’t already, please be sure to increase your community and public education efforts focusing on personal protection and source reduction.

Here is a graph that shows where we are this year as of week 27 with infection rates in mosquitoes compared to 2012, an epidemic WNV year (blue line), and 2016, a relatively average WNV year (orange line):

For more information, see the current Ohio arbovirus surveillance update at http://www.odh.ohio.gov/arboupdate.  The data on this website was last updated on 7/16/18 and will be updated each Monday thru mosquito season. Please call the Zoonotic Disease Program (ZDP) at (614) 752-1029 if you have any questions.

Minimum Infection Rate: West Nile Virus

West Nile virus activity has been increasing, and it has now been detected in mosquitoes in 14 counties as of noon on 7/9/18.  Of the 4,832 pooled mosquito samples (141,835 mosquitoes total) tested so far, 110 samples have tested positive from Athens (1), Delaware (1), Franklin (43), Hamilton (1), Hancock (1), Licking (4), Lucas (25), Portage (12), Richland (3), Ross (1), Stark (1), Summit (15), Tuscarawas (1) and Wood (1) counties.  This is up from 26 positive samples reported in the last message.  No human cases have been reported so far.

Here is a graph that shows where we are this year as of week 25 with infection rates in mosquitoes compared to 2012, a high WNV activity year (blue line), and 2016, a relatively low WNV activity year (orange line):

 

For more information, see the current Ohio arbovirus surveillance update at http://www.odh.ohio.gov/arboupdate.  The data on this website was last updated on 7/9/18 and will be updated each Monday thru mosquito season.

Ohio Arbovirus Surveillance Updates

Beginning this year, the Ohio arbovirus surveillance update can be found on the ODH website at http://www.odh.ohio.gov/arboupdate .  The table will be updated each Monday through mosquito season.

Ohio Mosquito-borne Disease SurveillanceFight the Bite! Avoid, Plan, Stop
June 18, 2018

Mosquito season is here.  The Ohio Department of Health (ODH) Zoonotic Disease Program, in partnership with ODH Laboratory, local public health partners and sanitary district partners, collects and tests mosquitoes from many communities in Ohio as part of statewide mosquito-borne disease surveillance.  This surveillance also includes monitoring for human and veterinary cases as well.

Full Update:   http://www.odh.ohio.gov/arboupdate

 

 

Study Suggests Culex Mosquitoes are Unable to Transmit Zika in the U.S.

Researchers have identified the Zika virus in mosquito species other thanAedes aegypti, which is largely responsible for the current outbreaks of Zika infection, raising concerns that other mosquitoes may be capable of transmitting the virus. However, a new study demonstrates that mosquitoes in the genus Culex are highly unlikely to transmit the infection to humans in the United States. The study was published inVector-Borne and Zoonotic Diseases.

The report demonstrates that the most widespread and abundant Culexspecies in the United States are very resistant to Zika virus infection, even when exposed to high levels of the virus in bloodmeals. The study showed that the southern house mosquito (Culex quinquefasciatus), for example, is refractory to infection with Zika virus. This finding has important implications for Florida and other emerging areas of Zika virus infection, and the authors recommend that mosquito-control efforts in areas of Florida with non-travel-related cases of infection should continue to focus on Aedes species.

According to University of Aix-Marseille visiting Professor Ernest Gould, who was not involved in the study, “[This paper] describes laboratory experiments to assess the transmission competence of Culex species and provides strong evidence to support the view that Culex species mosquitoes are highly unlikely to be important vectors of Zika virus. This report provides very helpful guidance for health agencies charged with the responsibility of controlling local mosquito populations in regions of North America where Zika virus presents a potential threat.”

However, an unpublished study from Brazil has shown that BrazilianCulex quinquefasciatus can be infected with Zika virus, and that Culex quinquefasciatus has been found in the city of Recife, where Zika is known to occur.

Read more at:

Culex Species Mosquitoes and Zika Virus