Disproportionate pneumonic cases in Madagascar plague outbreak

The African island nation of Madagascar is reporting an outbreak of plague which has infected 86 people, killing 39. The more deadly--and contagious--pneumonic form of the disease represents 90% of cases.

Madagascar is a well known focus of plague and has recently led the world in cases. Madagascar is also the site where a naturally occuring multi-drug resistant strain of plague was discovered.

The United States reports a few cases per year, the great majority of which are of the bubonic form. These cases are almost exclusively from the western half of the country as the rodent populations which serve as the reservoir for the plague bacillus (Yersinia pestis) seem not to move east of an artificial plague line which falls roughly on the 100th meridian. 

A few months ago, when a squirrel in Los Angeles County tested positive for plague, I was interviewed by Erin Burnett on CNN on this topic.

What is most interesting about the current cases in Madagascar is that they are of the pneumonic form and not the much more common bubonic form. It is crucial to understand the reason behind the disproportionate number of the pneumonic cases.

Botulism aka "sausage fever" in Texas

Coincidentally on the same day that I delivered a lecture on various bioterrorism topics, four cases of botulism were reported in Amarillo, Texas. During my lecture, I reminded the audience that botulism was once known as "sausage fever", provoking snickering in the crowd.

Remembering that botulus is the Latin word for sausage helps reinforce the fact that many botulism cases in the US are food-borne, often linked to home-canned substances (as these cases will likely turn out to be). Learning several important pieces of information regarding the  4 cases, who are all known to each other and 3 of whom have household contact, will be essential. Answers to the following questions will be crucial in the investigation:

• Has confirmatory testing been done?
• Is the same toxin type responsible in all cases? 
• Why did only 2 of the 4 meet criteria for antitoxin administration?

Another recently reported development with botulism was the discovery of a new of an 8th toxin type, for which no anti-toxin is currently available.

Dengue Fever: Back in the USA?

There has recently been an uptick in media reports focused on the threat of the mosquito-borne dengue virus in the US. The latest is an article, in which I am quoted, that details the mosquito control efforts of California, a state where no cases have been detected. 

Until this year, local spread of dengue was know to have occurred in Texas (chiefly along the border with Mexico), Florida, and Hawaii, the details of which can be found in a paper my colleagues and I wrote on the topic. This year, however, in addition to the uncovering of evidence of local spread in Houston, a locally-acquired case was detected in New York.

The key thing to remember with respect to dengue is that since the Aedes mosquito is present over a large swath of the US and there are a continual stream of potentially infected travelers--who may be asymptomatic--it is not surprising to find instances of local spread of dengue occurring in the US. In fact, serosurveys along the Texas-Mexico border have shown up to 40% of individuals exhibit evidence of exposure to dengue. 

Clinicians and public health officials should keep these facts in mind when investigating or treating unexplained febrile illnesses.

Cervical Cancer: Hopefully a Relic of the Past

Last night on an episode of Showtime's Masters of Sex, a drama focused on the research of Dr. William Masters and Virginia Johnson, the early work to encourage uptake of the now ubiquitous pap smear was portrayed. This test, developed by Dr. Georgios Papanikolaou, has proved to be essential in early detection of cervical cancer, whose cause is chiefly the human papilloma virus (HPV). 

In the episode a physician--played by Julianne Nicholson--is an early promoter of the procedure who is, herself, dying from cervical cancer. 

It is largely due to the early detection of cervical cancer via routine pap smears that such deaths are almost a relic of the past in the US. However, approximately 4000 deaths per year in the US are attributed to cervical cancer. 

Vaccines against HPV, as a supplement to routine pap screening, offer the promise of further decreasing the burden of cervical cancer. Currently, two vaccines are available: Merck's Gardasil and GSK's Cervarix. Both vaccines protect against the most common cancer causing strains of HPV while Gardasil offers additional protection against strains of HPV that cause genital warts. The vaccines likely offer protection against other HPV-caused cancers (vulva, vagina, anus, oropharyngeal) and are now part of routine childhood immunization schedules after much political wrangling (see Three Shots at Prevention: The HPV Vaccine and the Politics of Medicine's Simple Solution). 

Chikungunya Virus in St. Martin

The Caribbean island of St. Martin is reporting two cases of the mosquito-borne viral illness Chikungunya with 34 additional probable or suspect cases. This is an important story because, to date, this virus had not been found in the Caribbean. Chikungunya is infamous for causing a large outbreak on the Reunion Islands in 2006 (after importation from Kenya) that went on to spread to various nations of Asia and Europe.

This virus is transmitted by the Aedes mosquito which is widely distributed in both the Caribbean and the US. It is also the vector for dengue and yellow fever. While 2 cases of chikungunya might represent recognition of travelers infected elsewhere--as has been reported in the US--34 cases are likely the result of autochthonous (local) transmission. 

As such, these cases in St. Martin may represent the tip of the iceberg. It would not be surprising to find more cases in other Caribbean islands or even on the US mainland were Aedes mosquitoes abound and are readily available to bite viremic travelers.