Import risk analysis: Llamas (Lama glama) and alpacas (Vicugna ...

24. Coxiella burnetii
24.1. HAZARD IDENTIFICATION
24.1.1. Aetiological agent
Coxiella burnetii is an obligate intracellular gram-negative bacterium that causes the
disease Q fever.
24.1.2. OIE list
Q fever is listed but there is no Code chapter.
24.1.3. New Zealand status
Listed as an exotic and notifiable organism (MAF 2009).
24.1.4. Epidemiology
Q fever occurs world-wide with the exception of New Zealand (Worthington 2001),
Iceland (OIE 2009) and possibly Norway (Jensenius et al 1997).
C. burnetii probably infects all mammalian species, birds and many arthropods (Marrie
1990; Marin & Raoult 1999). In animals the infection is of minimal economic importance
and rarely causes disease, but C. burnetii is a zoonotic organism that sometimes causes
serious disease in humans. Most human infections are asymptomatic or present as a mild
flu-like condition. Acute or chronic infections sometimes occur and sometimes result in
serious complications such as myocarditis, endocarditis, hepatitis and renal failure (Marin
& Raoult 1999; Woldehiwet 2004). C. burnetii causes sporadic abortions in both humans
and animals (Raoult et al 2002; Hatchette et al 2003).
Transmission frequently occurs from contact with infected uterine discharges and
placentae and probably by inhalation of dust contaminated by animals and their birth
products (Behymer & Riemann 1989; Marrie 1990; Hawker et al 1998; Marin & Raoult
1999; Tissot-Dupont et al 1999). Infected ticks may also play a role in spreading the
disease. At least 40 species of ticks from 11 genera can be infected and their dried faeces
form dust that can contaminate animal coats. Infected cattle shed the organism
intermittently in their milk after successive parturitions (Kelly 2004).
Infected animals generally show few clinical signs thus making the determination of the
incubation period and the interval to the development of antibodies difficult. In humans the
incubation period is given as 1-3 weeks and the development of detectable antibody titres
takes 2-3 weeks after the onset of symptoms (Marin & Raoult 1999). It is assumed that
infected camelids will develop antibody within a similar time interval after infection.
The infection is diagnosed by serological tests or by identification or isolation of the
organism. The ELISA is considered to be more sensitive than the complement fixation test
(CFT) when testing cattle and sheep. However, for camelids the CFT is recommended
since the ELISA has not been validated in this species (Kittelberger et al 2009). The
Manual does not prescribe a test for international trade, but the CFT is listed as a suitable
alternative test for use when importing/exporting animals.
MAF Biosecurity New Zealand Import risk analysis: Llamas and alpacas from specified countries ● 85