Donald Kaye, MD, MACP

Babesiosis in humans is a tick-borne infection. In the United States, babesiosis is usually caused by the protozoan Babesia microti, an obligate intracellular parasite of erythrocytes. B. microti occasionally causes disease in Europe, Asia, Central America and Australia. Babesiosis is transmitted by different ticks throughout the world, mainly to wild and domesticated animals. Another species, Babesia duncani, has been the cause of babesiosis cases on the West Coast of the U.S. In Europe, most cases of human babesiosis are caused by Babesia divergens, which has also caused a limited number of cases in the U.S. Unlike B. microti, nearly all symptomatic cases caused by B. divergens are severe and occur in people without spleens. Babesia venatorum is another cause of babesiosis in humans and is found in Europe and China. This discussion will be limited to babesiosis caused by B. microti, which is responsible for the vast majority of cases of babesiosis in the U.S.

Nipah virus (NiV), an RNA virus, and Nipah virus infection (NiVI) are relatively recently discovered entities. NiVI is a particularly lethal infection, with a mortality rate usually higher than 50%. Its reservoir is the flying fruit bat, but it can infect a wide range of mammals, including humans. NiV has been cited as a potential agent of bioterrorism because of many suitable physical attributes of the virus and the high mortality caused by the infection in people. Although there is no evidence of any country or group attempting to weaponize NiV, the potential certainly exists.

Herpes zoster (HZ) continues to be a relevant public health issue because of its prevalence and potential complications. It is estimated that one out of three people in the United States will develop HZ in their lifetime. Varicella zoster virus, the cause of HZ, is one of eight herpes viruses that infect humans.

Primary amebic meningoencephalitis, or PAM, caused by Naegleria fowleri is a rare disease, fortunately. However, it will undoubtedly increase in frequency because of global warming. The usually fatal infection is caused by the free-living ameba, N. fowleri, which is found in warm fresh water and in soil all over the world. It exists in three forms: the infective trophozoite and the noninfective flagellate and cyst. It is thermophilic and will grow at temperatures of up to 115°F. It has been isolated from bodies of fresh water such as lakes and rivers, as well as inadequately chlorinated swimming pools, hot springs, thermal discharges from power plants and mud. It has been found in the nasal passages of healthy children swimming in canals in Egypt. It is not found in salt water. N. fowleri normally feeds on bacteria, but when it causes disease in humans, it feeds on brain tissue.

Today we have access to a multitude of new and novel medications, biologic agents, medical devices, imaging modalities, and surgical and nonsurgical invasive procedures, which have transformed the practice of internal medicine from what was essentially a diagnostic profession to one that is now heavily focused on treatment. Although the subspecialty of ID has been treatment oriented for many years, the advent of many new and sophisticated tests means we should turn our attention to potential improper use of the clinical laboratory — a major cost center in any health care system. This brings up the less often addressed but surely relevant concept of laboratory stewardship.

Although smallpox has been eradicated, monkeypox has not. Monkeypox, which can easily be confused clinically with smallpox, should it ever reappear, is a disease found in central and western Africa. Although the reservoir is thought to be primarily in rodents, outbreaks can occur in other mammals including monkeys and humans. The virus has been isolated from wild animals in nature only twice, once from a rope squirrel in the Democratic Republic of the Congo, or DRC, and once from a sooty mangabey in the Ivory Coast. Monkeypox is probably a very old disease, although it has been recognized only in the past 50 years.

Acute flaccid myelitis, or AFM, is not a new syndrome or disease. The classical cause of the syndrome is infection with the poliomyelitis virus. Of course, there has been no poliomyelitis originating in the United States since 1979. Sporadic cases of nonpolio AFM have been recognized in the U.S. for many years after the eradication of polio, but it was not until 2014, when there was a surge of cases in the U.S., that it reached the national consciousness and was given the name “acute flaccid myelitis” rather than “polio-like syndrome,” “acute flaccid paralysis” or other names that had been previously attached to the syndrome.

In previously healthy children, varicella (chickenpox), caused by varicella-zoster virus, or VZV, is almost always a mild disease. In fact, before the vaccine became available in the United States, “chickenpox parties” were a common occurrence in which children were brought to the house of someone with varicella so they could “share” the disease and develop an immunity after becoming infected. In the anti-vaccination communities, these “sharing parties” are still common. However, in the age of vaccination, this is not a good idea. The infection can be severe in infants and adults and is especially problematic during pregnancy and in immunocompromised individuals. The importance of varicella — in addition to the production of chickenpox and its complications — is twofold. First is the long-term persistence of the virus in latent form in sensory nerve ganglia, later developing into herpes zoster in many people, and second is the misdiagnosis of smallpox, which has implications of biowarfare, especially in war zones. As an example, a recent outbreak of chickenpox in Yemen (a country in the midst of a civil war and where there is no viral diagnostic capability) was initially reported by some news media as smallpox.

Currently, all eyes are on the worrisome Ebola virus disease outbreak going on in the northeast of the Democratic Republic of the Congo. However, this is not the only hemorrhagic disease that merits our attention. WHO and the Coalition for Epidemic Preparedness Innovations has identified Lassa fever as an important threat to global health and in urgent need of research and development efforts.

Each day, blood and cerebrospinal fluid cultures are considered the most significant tests that are requested from the clinical microbiology laboratory by essentially all hospitals. Objectively speaking, the term “bacteremia” simply refers to the detection or presence of a bacterial organism in the bloodstream. No more or no less. Analogous to a chemical assay that identifies elevated potassium (hyperkalemia) or diminished sodium (hyponatremia) levels, the detection of bacteremia in and of itself does not necessarily nor specifically point to any one precise infectious process any more than the other so-called “emias” define the explicit entity that is responsible for an aberrant amount of these ions, which are vital for the functioning of all living cells. In effect, the recognition of their presence merely calls attention to any one of several potentially dangerous pathophysiologic disorders disrupting normal electrolyte homeostasis or, in the case of bacteremia, to the fact that an endogenous or exogenous microbiologic organism has, for an array of possible reasons, invaded the routinely sterile blood. In fact, bacteremia is one of only two microbiology test results (positive cerebrospinal fluid culture being the other) that is included on the list of laboratory-critical values put forth by both the College of American Pathologists and the American Society for Clinical Pathology and adopted and employed by almost all certified laboratories.