Carlsbad Area Malaria Threat Is Fading Fast

Preventive measures taken by San Diego County health officials and the winding down of mosquito season are combining to reduce the threat of malaria around Agua Hedionda Lagoon near Carlsbad.

County Health Director Dr. Donald Ramras said the program against malaria, which includes spraying and monitoring mosquitoes and distributing medication to field workers in the area, will be continued for at least two more weeks.

“We’ll probably keep a weather eye out” after that because a five- or six-day Santa Ana condition could encourage new mosquito breeding and the possibility of a new outbreak, Ramras said.

He said no new malaria cases have been reported in the last few weeks, and only one malaria-carrying mosquito has been trapped this week. After the first spraying of the season, 150 were trapped in one night, but the numbers were much lower by the beginning of September.

Since July there have been 26 reported cases of vivax, a mild form of malaria, in the area around the lagoon. Ramras said 24 cases involve Mexican field workers and two involve Americans, one of whom travelled in Mexico several times in the last year.

He said the majority of cases involve field workers who sleep outside in an area about “the size of a football field” near the lagoon. If they had screened housing, the problem wouldn’t have been nearly as severe, he added.

Many of the field workers are from malaria-prone areas of Mexico, and the anopheles mosquito that breeds in the area is among the species that can transmit the disease.

Chloroquine tablets have been distributed weekly to about 200 field workers in the area, Ramras said. Chloroquine kills the malaria parasite in the bloodstream, but it must be taken over a period of weeks.