Working with Enviromental Health, and Vector Control

Working with the County Department of Environmental Health, and Vector Control
Gary Erbeck, Director Dept. of Environmental Health
Jack Miller, Chief of Community Health Division

Over the years, the Office of the County veterinarian (OCV) has worked closely with the Dept. of Environmental Health (DEH) to diagnose zoonotic and vector borne diseases in San Diego County. Both Depts. are concerned with the same diseases. The collaboration between the departments became even more important with the introduction of West Nile Virus (WNV) into California and the emerging threat of avian influenza. Because DEH lacked a laboratory facility for disease diagnostics, an opportunity presented itself with the creation of the new laboratory facility to enhance the diagnostic capabilities of both programs. Because of DEH's and OCV's mutual interests in zoonotic diseases, DEH funded 2 positions in the San Diego County Animal Disease Diagnostic Laboratory (SDCADDL) to develop and perform diagnostic tests for vector borne diseases.

Raining Birds, an environmental health concern?

We all know that "raining cats and dogs" is just a metaphor, but in 1988 reports of birds falling out of the air dead caused considerable concern at Lake Murray in east San Diego. Over 100 pigeons, coots, muscovy ducks, mallards, starlings and one cormorant died in two days. The Department of Enviromental Health was concerned over the safety of the water. The almost concurrent deaths of so many species tended to rule out an infectious disease and pointed to a toxin or poison. Lake Murray, being a public water supply, increased concern for public safety, and this was before bioterrorism entered the news. Dr. Mahoney, as pathologist in charge of our investigation, noted prolapse of the male reproductive organ of the muscovy ducks, a classic sign of a cholinesterase inhibitor. The laboratory confirmed toxic levels of diazinon, a cholinesterase inhibitor, in the blood of necropsy samples. To determine the source of the toxin, Dr. Mahoney made a field investigation and found diazinon, used as ant control, around a food vendor's stand. When the walkway was swept, the diazinon granules ended up on the grass where ducks were being fed. The birds found the granules enticing, and lethal. Problem solved. Water safe. Public reassured. No bioterrorism. This case illustrates the laboratory's important role in an era of bioterrorism.

The Case of the Errant Centrifuge, or the Water Ain't Poisoned after all.

In the 1980's our office was contacted by the health department regarding allegations that the ground water from wells in Alpine was contaminated and causing anemia in goats. The local paper also carried the story causing considerable concern among local residents. The health department, having tested the water and having found nothing unusual, and knowing nothing about goats, turned the case over to our department. Dr. Miller, our epidemiologist, contacted the goat owner who was convinced the water had made his goats anemic. He said he had run hematocrits and proved the anemia. This is a method for determining the volume of erythrocytes in centrifuged oxalated blood expressed as a percent of the blood sample. Standard techniques are essential for accurate results. When asked how fast his centrifuge ran the owner replied "real real fast." Suspecting nonstandard centrifugation and other errors were involved, Dr. Miller took our laboratory hematocrit centrifuge (shown above) and a very long extension cord along with the standard text in veterinary hematology to the farm to test the goats himself. Since the health department had found nothing wrong, the owner, being suspicious of a government coverup, had refused to allow the samples to be taken to our laboratory. Needless to say, all samples were normal as were the goats.

Crab lice, also known as pubic lice

These are world wide human external parasites. They get the name from their crab-like claws, not because they make a person crabby, although that may be the case. In 1978 a young man submitted a specimen as a tick from his dog for identification. It was much smaller than a tick. Its unmistakable crab-like claws immediately identified it as a crab louse, a human-only parasite. Being Dr. Mahoney's case, it fell to her to relate the nature of the louse and that it was not from his dog. I think Dr. Mahoney, being very young at the time, was about as embarrassed as the fellow who really blushed and quickly claimed it was not from him but from his girl friend. There is a saying among sailors that there is no stigma associated with pubic lice unless they are on one's eyebrows. Entomology students at U.C. Davis in the 1950s, and perhaps still today, had a place in Sacramento where they purchased crab lice for their cigar box insect collections. They would mount a lens in the center of their box and claimed it was worth one higher grade point for their collection.

Tularemia in San Diego County
Tularemia ulcer in human skin

In the summer of 2002 a resident of Encinitas reported observing occasional young wild rabbits dying near her house over a 2-3 year period. Since she lived next to a golf course, she thought the cottontails were being poisoned intentionally. After finding no poisonous or toxic substances were used at the golf course or by the neighbors, she contacted our laboratory to submit a recently dead rabbit that had shown neurologic signs prior to death. The carcass was delivered on July 22, 2002 for disease surveillance. The person indicated she was concerned about her domesticated angora rabbits she kept in her premises, but had not experienced any deaths or sick rabbits in her own collection. A necropsy (autopsy) was performed by Dr. Mahoney. Initial findings were multiple pinpoint bleeding spots on the skin of the inner thighs, and small white scattered spots with a granular appearance in the liver near the gall bladder. The spleen was enlarged. A heavy growth of the bacteria known to cause Tularemia (Francisella tularemia)was isolated and confirmed by DNA markers (PCR). This was the first confirmed case of Tularemia in any species of animal in San Diego County. This confirmed case identified a possible endemic area of the county. This facilitated County Vector Control, a division of the Department of Environmental Health, to conduct a survey of the Encinitas area collecting ticks during July, August, September, October, and November of 2002. The disease proved more widespread than first thought with 51% of the ticks testing positive for a closely related "symbiont" in our laboratory. One of these ticks that tested positive was collected off the clothing of a county employee, who fortunately had not yet been bitten. The bacteria can be transmitted to humans by ticks or biting insects such as deer flies and horse flies, ingestion or handling infected animals, and possibly from contact with contaminated water, food or soil. Tularemia was one of several biological weapons stockpiled by the U.S. military in the 1960's. The Soviet Union continued production of antibiotic resistant strains into the early 1990's.
Lyme Disease

Photo of tick on a person's skin, and the same tick enlarged on the tip of a pencil
Our office works with County Vector Control on tick borne diseases by providing PCR testing for plague, lyme disease, and tularemia. We also provide for anesthetic drugs and training to use on rodents for collecting blood samples and for microchipping for identification and monitoring purposes.

Sarcoptic mange.

Human case on the arm from family dog and Canine case involving ears and head
Human cases of Sarcoptic mange are hard to confirm as the parasites are few and very difficult to find in skin scrapings, while in dogs they are numerous and easily identified. The problem in treating is that this is a burrowing mite. While insecticide products are effective in killing the mites, they remain in the skin as foreign bodies causing the itching to persist, and causing the victim to over medicate.

Bird mite rashes.
Bird mite rashes of people are fairly common and so hard to diagnose in an office setting that physicians often suspect a psychosomatic disease. These cases often come to our attention. In these cases the mites do not burrow, but bite and run. None will be present at the time of examination. A field examination will usually confirm bird nests in the area that have been recently vacated leaving the mites looking for their next meal. The solution is to trim trees so branches do not touch the building providing a "runway" for the mites. Bird nests in eves, roofs, and ledges must also be removed.