A Psittacosis Outbreak in Costa Rica Associated with Pet Birds Imported from the United States
The importation of pet birds into the United States has been regulated to insure that exotic avian diseases do not find their way into the poultry industry or human populations.1 However, evidence exists suggesting that birds infected with chlamydia psittaci are being exported from the United States to Costa Rica. The association between imported birds, an outbreak of psittacosis specifically affecting a large collection of psittacines in Costa Rica, and the potential impact the importation of disease can have on endangered wild birds will be discussed.
Psittacosis (Chlamydia psittaci) has not been documented in Costa Rica’s wild2 nor captive native bird populations,3 nor in random testing of psittacines in Peru4,12. The prevalence of this zoonotic disease among pet bird populations in the United States, as randomly detected using indirect fluorescent antibody serology (IFA) is 5–6% (C. Cray, personal communication), and has been reported to be as high as 70%5 in selected U.S. populations, utilizing other detection methods cited in this study. Because of the complex biology of these obligate intracellular bacteria, detecting exposure and defining infection can be challenging. As well as IFA, diagnostic methods used in this study include immunoassays (ELISA), direct compliment fixation (DCF), elementary body agglutination (EBA) and gene-based diagnostics such as polymerase chain reaction (PCR) technology.
Pet bird ownership is common in Latin America. Although the traditional source is poaching, pet bird importation is not uncommon, and many non-native species are noted throughout Costa Rica. In a separate study of captive birds in Costa Rica, 78 of 261 birds examined (30%) were non-native species, and of those, 57 were old world species.3 In 1995 a flock of over 50 psittacines recently imported from the United States were found to be clinically ill. Subsequently five of 26 survivors tested positive for psittacosis (IFA and/or ELISA).
More recently, more birds imported from the United States have been implicated in an outbreak of psittacosis among a collection of 132 psittacines, including 94 macaws which are in a captive breeding-for-release program. As a result, 66 scarlet macaws (Ara macao) and 28 great green macaws (Ara ambigua) have been placed at risk. Both species are considered highly endangered (CITES I),6 and remaining wild populations are estimated at fewer than 400 scarlets and perhaps as few as 40 pairs of green macaws in all of Costa Rica7. In November 1995, all birds in the collection had been examined and were seronegative for psittacosis (IFA).3 A protocol for new acquisitions was established, including quarantine and chlamydia testing. Unfortunately, in June of 1996 after only a brief quarantine, a scarlet macaw was moved directly into the main breeding facility, which consists of two large open-air aviaries one containing 32 scarlets, the other 26 green macaws. Hatched in Costa Rica from native parents this scarlet originated from a facility which frequently imported psittacines from the United States. Many of the birds at that facility were free flying, no quarantine protocol was followed; native birds were housed with imports. In August 1996 that facility provided a second scarlet with the same background. The bird entered quarantine and was subsequently found to be seropositive (IFA) for psittacosis. Further testing revealed that the first acquisition was also positive (IFA), as now were its cage-mate and other birds in the aviary, some of which were clinically ill. The entire facility was quarantined, and all birds were treated for psittacosis with a diet containing 1% chlortetracycline for 45 days. An extensive environmental cleanup operation was also carried out. Additional tests (EBA, DCF and IFA) indicated that further exposure had occurred.
IFA may detect humoral antibodies for up to 7 months after an infected bird has been successfully treated for psittacosis (C. Cray, personal communication). Eleven months after the chlortetracycline treatment was completed, birds were re-tested. Evidence of exposure and/or infection had increased in the main breeding aviaries. Newly positive birds were identified throughout other areas of the project, young birds being particularly affected.
A second attempt to eradicate the disease was begun. Despite the expense and risks, a regime of doxycycline injections was selected. Infection does not provide effective immunity and failure to eliminate the organism from the environment is a common source of re-infection.8 Thus, another extensive environmental clean-up took place. It may be impossible to eradicate psittacosis from a flock of this size (A.M. Fudge, personal communication).8 C. psittaci in fecal material persists in the environment and is easily aerosolized. Birds sharing the same airspace as infected birds are considered exposed (A.M. Fudge, personal communication). The flock from which the first two seropositive scarlets originated is still free flying in a remote area of Costa Rica near private reserves and a national park, possibly posing a direct threat to wild psittacines.
Largely because of economic risks to the poultry industry, the U.S. Department of Agriculture requires quarantine, exotic disease testing and prophylactic treatment with chlortetracycline of psittacine birds imported from Latin America into the United States.1 Interestingly however, none of these are required by agencies in either government to import birds into Costa Rica. Tourism is Costa Rica’s leading source of foreign currency9 and relies heavily on a reputation of abundant flora and fauna. The presence of free flying psittacines is one of the attractions most frequently cited by tourists visiting Costa Rica.10 Because both scarlet and green macaws are large, colorful, raucous birds they are particularly appealing to tourists.9 Considering tourist expenditures to see macaws, Vaughan estimated that a free flying macaw in Carara National park, Costa Rica, may earn as much as $20,000.00 per year as an attraction.10 Similarly, Munn concluded that a macaw in Peru can generate up to $4,700.00 each year.11 By either estimate, psittacine associated ecotourism is big business. As traditional habitat destruction and poaching continue to represent a significant threat to populations of wildlife, it is important to prevent the possibility of further extinction pressure in the form of an imported disease, such as psittacosis.
This work was made possible with a grant from the Pfleger Foundation. Additionally, I thank the following individuals and institutions: Avian Research Associates, Texas Veterinary Medical Diagnostic Laboratory, Escuela Medicina Veterinaria de Costa Rica, the Mata Cambronero family, and the labor of many volunteers, including Dr. Susan B. Thompson, Jenifer D. Hilburn, and Magan Gehring.
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