science, health & technologyEl Nino and La Nina
Panama City metro area hit by a disease that's related to Rocky Mountain Spotted Fever
Health officials looking for vector in disease outbreak
by Eric Jackson
The Ministry of Health has identified an infection by a strain of the microbe Rickettsia rickettsii as the culprit in the strange deaths last October of three members of a family in the metro area neighborhood of Pedregal and other illnesses there and in nearby Santa Cruz. Three-year-old Niurka and five-year-old Fabiana Núñez and their pregnant 22-year-old aunt, Zaida Rodríguez, died of the mysterious illness. Rickettsia rickettsii infections tend to be tick-borne and cause a number of related diseases that include Rocky Mountain Spotted Fever and South American Tularemia.
The Health Ministry has been medicating area dogs against ticks as a precaution, although it admits that it's not known whether dog ticks are the vector here.
Santa Cruz and Pedregal are areas in which the Panama City - San Miguelito urban sprawl has pushed human populations into areas previously forested and thus into closer contact with wildlife and the parasites they carry. But 2007 was one of the rainiest years on record and that or climate change in general may have caused the migration of animals or animal parasites. In any case, Panama had not reported deaths from rickettsial infections since the early 1950s --- which doesn't mean that there were none, as a lot of tropical disease, particularly in remote rural areas, goes unseen by doctors or in any case unreported. The present outbreak is limited to a relatively small area north of the road out to Tocumen Airport, the Health Ministry's epidemiology director Gladys Guerrero told La Prensa.
Rickettsiae are microbes sometimes described as bacteria. They are more complex than viruses but more primitive than most bacteria. Precisely which kingdom into which they properly fit --- plants or animals in the old two-kingdom taxonomy, or bacteria in the new five-kingdom system --- is a matter of scientific controversy. They infect insects and the animals that these insects bite.
Rickettsia rickettsii cause a variety of spotted fevers in various parts of the world. With advances in DNA analysis, different diseases attributed to the same pathogen are now being identified as maladies caused by distinct species of germs. Thus "Rickettsia rickettsii" is now being described as the Spotted Fever Group of ricketssiae.
One of the spotted fevers, South American Tularemia, has in the past been of interest to biological weapons specialists as a possible incubus of mass destruction. Generally rickettsiae are not suitable biological weapons because they are hard to cultivate for mass production and do not easily spread directly from one human being to another. However, from another ghoulish perspective certain of them may be very suitable, in that certain ethnic groups are resistant to infections while other races or nationalities tend to get very ill and die.
Members of another branch of the Rickettsia tribe cause the various forms of typhus, including the murine typhus that's transmitted by fleas that infest rats and mice and is a problem in some of southeastern Brazil's slum neighborhoods and along the US - Mexican border. One of the horrors of World War I was the spread of typhus and the related rickettsial trench fever through the lice infesting the troops. On the Eastern Front more soldiers died from typhus than from combat.
Just which rickettsial disease we are dealing with here in Panama --- and whether the pathogen is actually known or is just a similiar species to one that has been described in medical or scientific literature --- are questions that have been left to the Gorgas Lab to answer. These days we have DNA analysis that can identify species and strains of microbes, but there has to be a database of prior samples for that to be very effective. That the Ministry of Health says that it has identified the microbe but not the vector suggest that its identification of the microbe and the disease may not fit precisely into known categories.
World health authorities are especially vigilant for "emerging diseases," mutant strains of known human infections or other maladies that had been present only in other animals but have now found a way to affect people. The Human Immunodeficiency Virus (HIV) that causes AIDS is believed by some scientists who have studied the question to have spread from African monkeys to humans and various flu strains that have swept through humanity are known to have originated among poultry or swine. An added fear is that a combination of global urbanization and climate change will express itself through new diseases or the presence of known ailments in places where they hadn't been found before.
El Nino and La Nina
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