11 Malaria Cases Linked to Carlsbad Lagoon Bugs

Eleven people have fallen ill of malaria since last month in an outbreak that San Diego County health officials say may be traced to a swampy lagoon near Carlsbad.

Nine of the victims are field workers who live in squatter camps east of the Agua Hedionda Lagoon, said Dr. Georgia P. Reaser, acting county health officer. Reaser said the field workers are Mexican nationals from the Oaxaca and Cuernavaca areas. The other two victims are U.S. citizens who live near the lagoon or frequent the area, she said.

The disease is usually not fatal and can be treated over a period of two weeks with medication. Reaser called the outbreak the “mildest form of malaria” and said the symptoms include high temperature, chills and headache. Malaria is caused by parasites transmitted from infected people to healthy ones.

Although there are usually 12 or 15 cases of malaria reported throughout the county each year, Reaser said that this outbreak is unusual because it is clustered in one area. Most of the cases reported during the year involve people who have traveled outside the country, usually in Third World nations, she said.

One of the U.S. victims of the disease said that he has traveled to Mexico three times since June, 1985. The other man said he has not been out of the country recently, but he takes nightly walks around the lagoon. Reaser said that female mosquitoes transmit the disease and that they bite during the early evening and at dawn.

Despite the likelihood that the undeveloped lagoon may be the breeding ground for mosquitoes that transmit malaria, health officials are not sure whether it is responsible.

Mosquitoes that transmit the disease favor stagnant water and malaria-carrying mosquitoes have been trapped at Agua Hedionda, Reaser said. But she said county officials still do not have “conclusive evidence” that the victims were bitten by mosquitoes that breed in the lagoon.

“But on the assumption that this is the case, we began fogging the lagoon area Thursday evening in order to kill the adults, and we began spraying for larvae on July 22,” Reaser said.

She said the first five cases were reported in early July by Tri-City Hospital in Oceanside. The first victim was hospitalized on July 4, and on July 16 hospital officials reported that they had treated five men, all Mexican nationals, for malaria, Reaser said. Last weekend four more cases involving field workers were reported by the hospital. Reaser said the nine men live in hovels without plumbing on the east side of the lagoon.

On July 7, a private physician reported to county health officials that he was treating a North County man for malaria, and on Thursday another local resident was reported by his doctor to be suffering from the disease.

Reaser said that the mild form of malaria detected in the 11 men is called vivax and is transmitted by the anopheles mosquito. For some unknown reason the malaria-carrying mosquito is attracted to carbon dioxide, so health officials are using dry ice to trap it.

County officials said that residents can help check the malaria outbreak by emptying containers filled with standing water. These include buckets, trash cans, old tires and children’s wading pools.