The usual suspects

It is not unusual for us to be asked, "What is going around?" It is often followed by a description of a respiratory or gastrointestinal malady that has afflicted a friend, neighbor or relative, maybe even the caller themselves. It should come as no surprise that many infectious diseases are seasonal. Flu is probably the best example, we are all accustomed to see and hear reminders that winter is the flu season.

Well, it turns out that due to the historic appearance of pandemic H1N1 in the spring of 2009 and then again in the fall, we have very little flu circulating now. H1N1 has succeeded in vanquishing its competition, the previous dominate strains were H3N2 and a run-of-the-mill H1N1. Where the pandemic H1N1 strain has gone is a question we epidemiologists wish we could answer, maybe soon. So, what is circulating causing upper respiratory illness in NYC? If you need to put a name to your discomfort, the suspects are called rhinovirus, metapneumovirus, adenovirus and respiratory syncytial virus (RSV). Variations on the common cold. In NYC adults, it has been mostly rhinovirus of late, in young kids likely RSV.

There are two known seasonal causes of viral gastroenteritis, norovirus and rotavirus. Norovirus season usually begins in November and peaks around now. It characteristically causes vomiting along with diarrhea. The vomitus is quite infectious and when aerosolized may infect people sharing space with the ill person. It is a good idea to wash your hands and face if you witness someone vomit. The illness usually takes 1-2 days to appear after exposure and in most people does not last more than a few days.

Rotavirus is a major pathogen in the developing world and is most dangerous to the very young who can quickly dehydrate from the watery diarrhea it causes. The season traditionally begins in the spring. There is a vaccine for rotavirus, recommended to be given in infancy.

Shades of Typhoid Mary- Part One

Part One

It was Indian summer nearly a decade ago. My first since returning to home after a seven year hiatus. Leela, our first ever foodborne disease epidemiologist, who we stole from CDC, came to my cramped cubicle. She looked troubled. It was a cluster of typhoid fever, the scourge of the 18th and 19th centuries. Typhoid fever is caused by the bacterium Salmonella Typhi and it only occurred in travelers to a country where the disease was endemic (meaning regularly occurs and never really goes away). I tried to reassure her, after all it was September and the disease took about a month to show up after an exposure. Perfect timing for those summer vacations back home many foreign born residents routinely made. Leela was no greenhorn. She had worked at the Foodborne Division at CDC and was an experienced and efficient epidemiologist. She already new that none of the seven cases had traveled. It wasn't unusual for an individual to try and hide their travel, whether for reasons of citizenship or otherwise, but for seven people to all claim no travel, that was unusual.

Part two

The thing about Typhoid fever, the singular feature that has allowed the organism to survive the sanitary movement of the 19th century and the modern antibiotic era, is its ability to induce a carrier state. Most people infected with Typhoid fever recover, but is some, as much as 5%, continue to intermittently shed the bacteria in their stool without any symptoms. Most people have heard of Mary Mallon, aka Typhoid Mary. She was cook for wealthy NYC families in the early 20th century and is perhaps the best know Typhoid carrier. The risk carriers pose is mostly from preparing food, though being a healthcare worker is another risky occupation for a carrier.

Leela sent the microbiology samples to the lab for DNA analysis. Pulse Field Gel Electrophoresis (PFGE) is a method used to determine if two or more strains share common genetic fragments suggesting a common origin. Not quite fingerprints, but close. The PFGE patterns of the seven patients was the same. Leela tallied the answers to the questionnaires finding a latin food restaurant in common for all but one case. We next headed out to Queens to pay a visit to the restaurant.