It's getting harder to ignore the risk of contagion in emerging markets that many investors have been pushing aside, even as conditions in Argentina and Turkey have worsened.

The news out of emerging markets this week has been decidedly glum. South Africa unexpectedly dipped into recession in the second quarter, with weak growth exacerbating continued jitters about the rand and raising the risk of a credit downgrade. Meanwhile, inflation in the Philippines jumped to 6.4% in August, from 5.7% in July, exceeding most economists' expectations and pressuring the central bank to raise interest rates–a troubling prospect as economic growth slows.

Indonesia's government tried an array of measures to lift its currency, which fell to levels not seen since the Asian financial crisis that wrecked emerging markets two decades ago. As strong economic data out of the U.S. lifts the dollar and rates head higher, investors are less interested in going to emerging markets—hitting their currencies and creating its own level of pain for countries.

Add to that concerns the U.S. may impose more tariffs on China, further escalating the spat between the two countries—and triggering a 2.6% selloff in Hong Kong's Hang Seng index. The iShares MSCI Emerging Markets ETF (EEM) is down 1.5% Wednesday morning for a year-to-date decline of nearly 9%.

William Jackson, chief emerging markets economist at Capital Economics, sees more pain ahead for emerging markets. Though he does not yet see macroeconomic strains outside Turkey and Argentina, Jackson says in a note that the relatively sharp increase in bond yields in Brazil, Russia, South Africa, and Indonesia will affect growth.

Developing countries are facing a perfect storm, according to Larry Brainard, TS Lombard's chief EM economist. In the research firm's September message to clients, he warned would-be bargain hunters that emerging markets have not neared a bottom.  While problems in Turkey and Argentina haven't been "systemic," Brainard wrote that a combination with several other crises now brewing could lead to a broader problem.

Here are the things Brainard sees as potential sparks for wider contagion:

• A further escalation of the U.S. and China trade spat that could affect $400 billion in goods could tip China's current account into deficit and push the yuan weaker by about 15%, Brainard says. That could ripple through other emerging markets as other countries are forced to lower their currencies to compete and eventually hit the global economy in a way emerging market troubles have not yet managed to do.
• The likelihood of a market-friendly candidate emerging as a winner in the upcoming first round of Brazil's election in early October is receding. Brainard says Brazil will likely have two extreme candidates, rather than a centrist, which would be "positively disturbing" for markets.  If that happens, investors fleeing Brazil could spiral through emerging markets, creating contagion in a way Argentina and Turkey—two smaller markets—have not yet done.
• While many expect Turkey's economy is headed for a recession, Brainard argues the real risk is a financial crisis as European lenders cut off financing to Turkey as bad debts rise—a scenario he thinks is not yet priced in markets.

Jon Harrison, managing director of EM macro strategy at TS Lombard, wrote in a separate note that India and Mexico stand out as relative safe havens among developing countries. The iShares MSCI India ETF (INDA) is down 4% so far this year, half as much as the broader EM index, while the iShares Mexico ETF (EWW) has inched up 0.44%.

But even these markets may not be so safe. Win Thin, global head of EM strategy at Brown Brothers Harriman, writes in a report that the Mexican peso is under pressure once more—a sign the country can't delink itself from the stresses elsewhere in emerging markets. He says the weak peso could feed inflation that forces the central bank to raise rates again.