A soft tick that lives ten years is why swine fever planners want the map now

This tick does not wait on vegetation the way the hard ticks on a dog's ear do. Ornithodoros turicata lives inside dens and burrows, feeds for often less than an hour, usually at night, then withdraws into a crevice ^{[11] [12]}. That habit is why the Texas A&M work is about persistence rather than spread. African swine fever moves between pigs mainly by direct contact, contaminated feed or meat, and contaminated environments ^[9]. In parts of Africa where the virus is endemic, though, it is maintained in wildlife by soft ticks of the same genus ^[10], and an animal that can live ten years or more and wait years between blood meals is a slow container ^[12].

The container sets the terms of any response. Countries where ASF has been introduced have gone through mass depopulation of herds, long-term trade restrictions and losses in the billions ^[16]. Saleh's argument is that a cull clears pigs, not premises: "Even if you depopulate infected pigs, infected ticks could reintroduce the virus when new animals are brought in" ^[21]. Take the ten-year figure at face value and the fallow period on a tick-occupied site is set by tick biology rather than by how soon a producer wants to restock ^[23].

The map is aimed at that problem. The model rates most of Texas as suitable habitat, excluding the eastern portion, and flags highly suitable ground in southeastern Georgia where the tick has not been documented ^{[13] [14]}. Average temperature in the warmest months and moisture in the wettest periods were among the heaviest-weighted variables ^[15]. Suitability is a statement about conditions, not occupancy, so the Georgia result is mainly an instruction to go and look, and the first collections there will be testing the model as much as the ground ^[19]. The authors say the findings are meant to prioritise laboratory testing and field collection ^[3].

The reason a low-probability event earns this work is that the loss would not scale with the number of sick pigs. The US pork sector contributes more than $50 billion a year to national GDP and supports more than 550,000 jobs in production, processing and export ^[1], which works out to roughly $91,000 of annual GDP standing behind each of those jobs ^[18]. Export access depends on disease-free status, and a detection would likely be followed at once by export bans and large-scale control measures ^[2].

Saleh is careful on both the odds and the model. "Even though introduction isn't probable, it's possible," she says, "and because the consequences are so severe, it warrants serious attention" ^[8]. On range, she notes that expansion is not only a response to temperature and moisture: wildlife host availability could decide whether tick populations grow or shrink ^[22]. Dee Ellis, the co-lead from AgriLife Research and the entomology department, is working the industry and stakeholder side of the same question ^[6], which includes whether Texas populations of the tick could sustain or transmit the virus at all ^[17]. Knowing which counties hold a candidate reservoir is the cheap part of that programme. Finding out during a quarantine is the expensive version.