Division of Disease Control and Health Protection

"The reason for collecting, analyzing and disseminating information on a disease is to control that disease. Collection and analysis should not be allowed to consume resources if action does not follow."

--Foege WH et al. Int. J of Epidemiology 1976; 5:29-37.

Please print out this material and share with epidemiology staff, county health department directors, administrators, medical directors, nursing directors, environmental health directors and others with an interest in information of this type. Thank you.

In this issue:

1. USDA and DACS Issue a Screwworm Alert
2. Shigellosis One-Pager
3. Weekly Disease Table: Week 14

Dr. Lisa Conti, State Public Health Veterinarian

State and federal agriculture agencies recently issued a screwworm alert after finding larvae in one horse imported from Argentina. In countries where it occurs, screwworm infestation causes considerable agricultural losses. During severe animal outbreaks, human cases can occur. There is no human health hazard to Floridians at this time.

Obligate myiasis (fly larvae developing in living tissues of warm-blooded animals) may be due to botfly or screwworm infestations. Neither insect is currently found in the United States. While people are not the usual hosts, they may become infested. Human botfly, Dermatobia hominis, infestation occurs in South and Central America. Botfly larvae cause painful dermal swelling with a central opening. Botfly larvae are transmitted to people after they emerge from eggs laid on bloodsucking flies (e.g., mosquitoes).

While relatively rare, human screwworm infestation can lead to considerable pathology. Chrysomya bezziani and Cochliomyia hominivorax are the Old World and New World (South and Central American) screwworms, respectively. The female fly can deposit 100-400 eggs directly on the host. Larvae cause channels in tissues and may feed more deeply than botflies. As with botfly infestation, treatment is physical removal of the larvae, though this may be surgically difficult with screwworm infestation.

While no additional animal cases have been identified, the Department of Agriculture and Consumer Services (DACS) and United States Department of Agriculture are requesting continued veterinary surveillance. Suspect animal cases should be reported to the Area Veterinarian in Charge, Veterinary Services, APHIS or to the State Veterinarian at DACS.

Roger Sanderson, MA, RN

Shigellosis is an acute enteric disease caused by gram-negative bacteria of the genus Shigella. There are four different species that are responsible for disease in the United States. Shigella sonnei comprises approximately 60 - 80% of all reported cases followed by S. flexneri, S boydii and S. dysenteriae. In the United States, an estimated 300,000 cases and 600 deaths from shigellosis occur annually.

In Florida, seasonal trends occur with the highest number of cases reported in June and the lowest in January.

1. American Academy of Pediatrics. Shigella Infections. In: Peter G, ed. 1997 Red Book: report of the Committee on Infectious Diseases. 24th ed. Elk Grove Village, Il: American Academy of Pediatrics; 1997:472-474.
2. DuPont HL. Shigella Species (Bacillary Dysentery). In: Mandell GL, Bennett JE, Dolin R, eds. Mandell, Douglas and Bennett's Principles and Practice of Infectious Diseases. Part II. New York: Churchill Livingstone, 1995: 2033-2039
3. Hoffman, RE. Shillam PJ. The Use of Hygiene, Cohorting, and Antimicrobial Therapy to Control an Outbreak of Shigellosis. Am J of Diseases of Children; 1990: 144: 219-221.
4. Mohle-Boetani JC, Stapleton M, Finger R, Bean NH et al. Community wide Shigellosis: Control of an Outbreak and Risk Factors in Child-Day-Care Centers. Am J Public Health. 1995: 85; 812-816.
5. Peterson, MA. Demographic Differences and Antimicrobial Resistance Patterns in Shigella Isolates, Hillsborough County, Florida January 1,1995 - July 31,1996. Thesis (M.S.P.H.) University of South Florida, 1996.