Every year the District collects ticks from recreational areas in the county to assess the risk of tick-borne disease. One way to measure this is by determining the minimum infection prevalence (MIP), which estimates what percentage of these ticks are expected to be carrying a given disease agent in a population. The laboratory has completed testing for two vector-borne diseases from ticks collected from November 2017 to May 2018.
Autumn is the time of year for termite swarms as adult winged termites (called alates), leave their colonies, mate, and establish new colony sites. Residents often see the swarms around their neighborhood or find discarded wings and dead termites scattered on the ground or caught in spider webs. Only a very small proportion of termites are successful in establishing a new colony.
As of September 28, 2018, there have been 330 dead birds reported in San Mateo County. Of those, 103 have been suitable for testing and five have tested positive (5%) for West Nile virus (WNV). Two mosquito pools have tested positive for WNV, both from East Palo Alto during the month of August. Positive birds and pools for 2018 are summarized in the tables below. No sentinel chickens have tested positive for West Nile Virus in San Mateo County in 2018.