BEIJING » U.S. universities have responded to China’s exploding demand for American higher education with branch campuses and aggressive recruiting. Now, some are trying to boost their brands by casting photos and other snippets of campus life out into the confounding sea of Chinese social media.

How confounding? Consider the mystery of the Chinese Yale zombies.

That’s “zombies” as in “zombie followers” on Sina Weibo — the hugely popular “weibo,” or microblogging, site that’s roughly akin to Twitter and has attracted more than 500 million followers since debuting in 2009. A common feature on Chinese social media, these zombie accounts could represent actual users who lurk inactively online. But often they’re fake, mass-produced accounts that mindlessly follow (hence the name “zombie”) and artificially boost another account’s follower numbers — and thus prestige.

Since its debut in December, Yale’s new Sina Weibo account — sharing photos and other assorted items from its Ivy-covered Connecticut campus — has exploded in popularity, apparently far faster than any other U.S. institution’s.

While other prominent universities have patiently accumulated at most a few thousand followers in more than a year of operation, Yale’s been adding nearly that many daily, and has passed 140,000. The only other foreign university even remotely close to that figure is, oddly, Peoples’ Friendship University of Russia. Yale’s Weibo account is ranked 30th in popularity among educational institutions overall, better even than several well-known domestic institutions like Nanjing and Zhejiang universities.

True, Ivy League Yale does have a famous name, longtime ties to China (it graduated the first Chinese person to earn a degree from a U.S. college in 1854) and 1,000-plus Chinese students and scholars currently on campus. That likely explains some of the growth. But Yale also appears to have attracted a mysteriously large battalion of walking dead accounts, with pages and pages of followers that rarely if ever post themselves and have few if any followers. Analytic software also points to some geographic oddities that could also raise suspicions of fake accounts, and many followers have disabled the feature allowing them to receive private messages.

Whence these zombie Yalies? After inquiries from The Associated Press, a Yale spokesman acknowledged some of the followers could be fake, but says that’s not Yale’s doing. He says the university isn’t buying followers, which can be purchased for a few cents each online.

“We don’t do it, we don’t promote it, we don’t encourage it, we don’t like it,” university spokesman Michael Morand said, adding: “Not to be cheeky about it, but it’s sort of like ‘Newsflash: Spam is inherent on the Internet.'”

Zinch, the marketing company that works with hundreds of overseas institutions in China and runs Yale’s Sina Weibo feed, also denies purchasing followers. It too says it’s mystified by Yale’s growth.

Sina, the company that operates Sina Weibo, has promoted Yale on its campus page and recommended it to new users, spokesman Mao Taotao said. But that wouldn’t explain why Yale has so many inactive followers. And he denied Sina adds followers to any account.

“To provide netizens with a clean online environment, Sina Weibo eliminates rubbish users in a timely manner,” he said in a written statement.

Another possibility: Companies that specialize in selling zombie followers may be signing their zombies up to follow Yale and other accounts to make them appear more real, said Cao Di, an analyst for the Shanghai-based Internet consulting firm iResearch.

In short, the bottom of the zombie Yalie mystery may be unreachable. And the whole matter could fairly be called a harmless curiosity.

Still, it offers a glimpse of just how swampy the new landscape of Chinese social media can be, and highlights some risks for overseas universities and companies. Accusations of inflated Twitter accounts have embarrassed politicians and corporations. In academia, concerns have been raised on many campuses — including Yale — about the dangers as universities expand their reach into foreign cultures.

Yale could lose face in China if it’s believed to be artificially inflating its numbers there, said Jason Lane, a University of Albany expert on internationalization efforts by U.S. universities. But more broadly, he said, the issue highlights how U.S. universities risk losing control of their brands and reputations in unfamiliar environments. Those risks are compounded by outsourcing the communications work to companies like Zinch or other local experts due to language barriers.

“Given the criticality of the Chinese market to the international dimensions of these institutions, I think it’s even more alarming that you’re releasing control of this aspect of your brand,” Lane said. “Part of oversight is knowing what they’re saying but it’s also a cultural issue of not really knowing how it’s playing.”

“This is part of the learning curve,” he added. “There are bound to be some hiccups along the way.”

There are nearly 200,000 Chinese students on U.S. campuses — up 25 percent just since last year, and the most of any foreign country, according to the Institute of International Education. But Twitter, Facebook, YouTube and other sites are banned in China. So U.S. institutions are gravitating to Sina Weibo to communicate with prospective students, alumni and even donors. An estimated 80 percent of Chinese university and high school students have accounts.

“We’re talking about a large audience of prospective students and alumni who aren’t necessarily able to interact with us the same way their counterparts in other countries are,” said Laura Brinn, Duke’s director of global communications.

Overall, U.S. universities are moving more cautiously into China than in the past, following setbacks. A planned campus by Duke encountered some faculty skepticism and construction delays, while Yale’s partnership with the National University of Singapore has been a major point of contention on campus.

That caution is reflected in social media experiments. Survey data from Durham University in the United Kingdom suggest schools in that country are further along than those in the United States. Some well-known U.S. names, like Harvard and Stanford, are still on the sidelines. Those in the game say they’re just experimenting, trying to figure out what works.

Duke, for instance, has discovered popular topics include its basketball team and research by faculty, particularly with a Chinese connection. Michigan creates its own specialized content in-house for Sina Weibo rather than just translating material from other feeds like Facebook. Many of its followers turned out to be Chinese students on its own campus, so Michigan’s using its feed to reach them. But it’s had some surprising “hits” in China, too, like the obituary of a Michigan faculty member who was an expert in medical drawings.

Yale reports that photos of its famous architecture — like a recent one of its arresting Beinecke Rare Book and Manuscript Library that Sina retweeted — are popular and deserve credit for at least some of the Yale account’s rapid growth.

“People are just going to put a lot of different stuff up and see what sticks,” said Nick Pearce, a Durham University sociologist who has been studying how universities use Chinese social media.

Duke has around 3,000 followers; Michigan recently passed 6,000. The University of California-Berkeley had about 11,000 but it hasn’t posted anything since last March 21, and a handful of U.K. institutions have passed 25,000.

Then there are two outliers: Peoples’ Friendship University of Russia, with more than 170,000 followers, and Yale with about 140,000.

Publicly available software that analyzes Sina Weibo accounts indicates about 95 percent of those following Yale have fewer than 100 followers themselves, and more than 93 percent have made 10 posts or fewer. More than one-third have never posted anything. By comparison, the figures for Zhejiang University, a well-known Chinese institution with a comparable number of followers to Yale, were much lower: only 26 percent have posted 10 times or fewer, and 6 percent have never posted. A recent analysis comparing Yale with Michigan found fewer than 2 percent of Yale’s followers post at least once a day on average; at Michigan the figure is nearly one-third.

Experts caution such software may be unreliable, and indeed results varied somewhat. But it also reveals some geographical oddities — though those too are hard to interpret. For instance, it shows roughly 20 percent of Yale’s registered from Hunan, a rural province known for its rice farming and chili pepper cooking style, and Yale gets high numbers in other rural areas. But only about 2 percent and 4 percent, respectively, of Yale’s followers appear to come from Beijing and Shanghai.

That looks very different from other universities, who typically have heavy concentrations of followers in cities, and a relative handful in places like Hunan (Michigan, for instance, gets more than a quarter of its Sina Weibo traffic from those two cities alone).

“If it is coming from one small (place) that is not likely to have high demand for higher education, something suspicious is going on there,” Lane said .

The AP attempted to reach 20 users from a random page of Yale followers. Sixteen of them were not set up to accept private messages, which is unusual on Sina Weibo. Of the remaining four, one had never posted, and two others have not updated since early 2011. The fourth did respond to the AP’s attempt to verify the follower’s authenticity.

Still, the software suggests some other non-university accounts also have surprisingly large numbers of followers from places like Hunan. Sina’s promotion of Yale likely has helped attract real followers. And an analysis performed for the AP by the Beijing-based new media information provider 36Kr.com found Yale had a respectable level of apparently real engagement, with many of its posts attracting comments and reposted by genuine followers.

Morand, the Yale spokesman, and Sid Krommenhoek, who leads Zinch’s global business development team, said Yale’s reputation at least partly explains the numbers. But both also insisted big numbers aren’t the goal.

“It’s the big name. It runs deep,” Krommenhoek said of Yale. “You kind of expect some schools to grow. It’s like, why Yale receives so many applications. But that’s not the important thing. The important thing is to find a good fit, to be engaging, and to have a real conversation.”

Still, Krommenhoek admits he’s flummoxed.

“No one sees this type of growth,” he said. “There are a lot of factors. We are very interested.”

U.S. universities say Sina Weibo is just a small part of a much larger, long-term strategy to connect with a huge and important country. But one lesson is clear: success can’t be judged by sheer numbers.

“In the whole industry, people don’t believe in that number anymore,” said King-wa Fu, assistant professor of journalism and media studies center at University of Hong Kong.

Pearce, the University of Durham expert, agreed that what matters is quality engagements, not quantity.

“If I was told ‘we need 100,000 followers and you’ll get a bonus,’ I could probably get them 100,000 followers but that wouldn’t be real engagement,” he said.

Still, Lane, the Albany expert on internationalization by U.S., universities, said the Yale Sina Weibo mystery underscores the risk of the unknown.

“You don’t know what you’re getting into when you get into other countries,” he said. “But when you cross into weibo, it’s a world unto itself.”

Justin Pope reported from Ann Arbor, Mich. Didi Tang reported from Beijing.