Stowaway rats, modern biohazards point to need for health inspections aboard ships

My first year as a cadet on California Maritime Academy’s training ship Golden Bear, we were moored during a port stay in Pago Pago, American Samoa. After a long day of swimming and sightseeing ashore, I was making my way down the dock toward the gangway. It was about 2000 and night had already fallen as a warm drizzle was coming down. Nearing the bollard where the bowlines were secured, a movement in the shadows caught my eye. Looking over, I was shocked to see a rat the size of a small dog standing only a few feet away from me on the bull rail, the large wooden “curb” at the end of the pier. Even with the mediocre lighting on the dock, I could see his furry rat face and beady eyes looking right at me — appearing wary but not necessarily afraid. As suspicious of him as he was of me, and not knowing what nasty diseases the rodent might transmit if he bit me, I eased back and we both went our separate ways.

Rats have been associated with shipping for thousands of years. Roman ships brought the black rat to the British Isles over 1,600 years ago. The brown rat, commonly known as the wharf rat, is found on every continent in the world except Antarctica — much of the spread attributable to being carried on ships and boats. Rats are vectors for many nasty diseases, including murine typhus, salmonellosis, trichinosis, leptospirosis and the plague. According to the U.S. government’s Centers for Disease Control and Prevention (CDC) the bubonic plague was first introduced into the United States in the early 1900s by rodents transported on cargo ships, causing outbreaks in several U.S. West Coast ports, along with two epidemics in San Francisco that killed hundreds of people. As late as the 1920s, rodents caused another plague epidemic in Los Angeles.

Around the same time that plague epidemic was hitting Los Angeles, a survey of ships docked in the port of New York showed that nearly 50 percent were infested with rats. Because of these and other incidents, there became a great concern that rodents carried on vessels would cause a worldwide pandemic, spreading horrific diseases from port to port and resulting in the deaths of millions. Consequently, increased inspections by public health officials and the aggressive employment of fumigating chemicals became commonplace. In addition, the use of rat guards for vermin control became widespread on commercial vessels. These round metal “shields” were designed to fit over a mooring line, and made it nearly impossible for rats to climb over and get onto or off the vessel. Though the federal government did not mandate their use, after several plague outbreaks some U.S. ports began to require that ships use rat guards when docked.

It wasn’t until 1951 that the World Health Organization (WHO) promulgated the new International Sanitary Regulations (ISR), which established official procedures to limit the spread of rats on board oceangoing vessels. For the first time in history, ships on international voyages were issued a Deratting Certificate, which was good for six months and required passing a full health inspection by government authorities before being renewed. Ships arriving from a foreign port that did not hold a valid Deratting Certificate could be inspected by health officials and issued a new certificate, detained and required to undergo a complete deratting/fumigation protocol, or be placed in quarantine and denied entry until fully cleared. The new sanitary regulations were only binding for countries that chose to be members of WHO, and then just to the extent they chose to follow the ISR protocols, because the organization itself had little if any enforcement capability to help ensure the regulations it had established were being adhered to.

At first, being a signatory to the ISR, the U.S. Public Health Service kept a close eye out for rat infestations on board vessels entering U.S. ports. Deratting inspections were conducted at 18 major and nearly 100 smaller American ports, with certificates being issued to vessels passing inspection, and measures such as fumigation of rat-infested ships were ordered when necessary. Then, in the mid-1980s federal funding for inspections was cut. The CDC suddenly decided that there was no problem, announcing that it would no longer routinely conduct deratting inspections on ships calling at American ports, and that vessels arriving from foreign lands did not need to have a valid Deratting Certificate for entry.

A 2005 study by the National Institute of Medicine concluded that the efforts of the CDC “no longer protect the U.S. population sufficiently against microbial threats.” Two years later, in 2007, WHO replaced the Deratting Certificate with a Ship Sanitation Certificate as part of the implementation of the revised International Health Regulations. Almost immediately, our government enacted a law continuing its longstanding policy of not requiring international ships coming into our ports to hold a valid health certificate. Countries such as Brazil, New Zealand and Singapore require international ships calling at their ports to have a current Ship Sanitation Certificate — but not the United States. These days the CDC makes periodic ship sanitation inspections of cruise ships, but does not conduct routine health inspections of any cargo ships arriving here from other countries — and has no publicly stated plans to do so. Evidently, in these high-risk times of killer viruses and bioterrorism threats, the CDC has decided that health inspections for thousands of vessels calling at our ports are unnecessary.

If a modern-day plague killed the same percentage of people today that died during the Black Death pandemic in the Middle Ages, close to 2.5 billion people would succumb worldwide — one in three Americans could die. That’s why I think it’s time for our government to stop playing “Russian roulette” with public safety, and revise its policies regarding health inspections of cargo vessels calling at our ports. In my opinion, all international ships should be required to carry a valid Ship Sanitation Certificate before they can enter our waters, and every cargo vessel arriving from overseas should have to pass a health inspection by the CDC before being allowed to dock in an American port. I believe that to mandate any less puts the safety of the American people at unnecessary risk.

Till next time, I wish you all smooth sailin’.     

Kelly Sweeney holds the licenses of master (oceans, any gross tons) and master of towing vessels (oceans), and regularly sails on a wide variety of commercial vessels. He lives on an island near Seattle. You can contact him at

By Professional Mariner Staff