"Re-Emerging Infectious Diseases: Should We Be Worried?", by Maridaliz Rodriguez-Rosado
Last summer, the Florida Department of Health issued a Mosquito-Borne Illness Advisory after four confirmed local Malaria cases in Sarasota. Malaria is a parasitic disease transmitted by an infected mosquito (the vector) from the species Anopheles. The causal agent is a blood parasite of the genus Plasmodium. Humans are considered the intermediate host for four species: P. falciparum, P. vivax, P. ovale and P. malariae. Infections with Malaria occur in areas where environmental conditions allow the parasite to replicate in the vector. Malaria cases are usually restricted to tropical and subtropical areas. This geographical distribution could be affected by population movement and climate change. Can we consider this parasite an emerging pathogen? Let’s define first what is an emerging pathogen. Emerging infectious diseases can be defined as infections that have newly appeared in a population or have existed but are rapidly increasing in incidence or geographic range, or that are caused by one of the NIAID Category A, B, or C priority pathogens which determine and response to emerging pathogen threats in the United States. Based on this definition, Malaria infections can be categorized as an emerging pathogen. Clinical manifestations include fever, chills, sweats, nausea/vomiting, and headache. Diagnosis can be missed if providers are not alerted to the possibility of this disease. Malaria can progress to severe forms that can be fatal. Patient history is a must when considering a suspicious malaria infection. Microscopic morphological analysis is the gold standard for Malaria diagnosis. Blood smears stained with Giemsa, Wright, or Wright-Giemsa stains can be visualized on both thick and thin smears. Presence of parasites can be visualized by thick smears, while thin smears are used for species-level identification. Both smears can be used for quantification. Comparison of the Plasmodium species which causes Malaria in humans are based in the stages found in the blood (ring, trophozite, schinzont, and gametocyte). Confirmatory Molecular Diagnosis can be used for the detection of Plasmodium species using using PCR analysis. In addition, antibody detection using indirect florescent antibodies (IFA) has been used to determine if a patient has been infected with Plasmodium. Antigen detection based on enzymatic activities associated with the parasite are used as rapid diagnostic test or RDTs. However, there is only one RTD kit licensed for use in the United States.
Summer is one of my favorite seasons of the year. But despite the intoxicating smell of the ocean breeze and BBQ gatherings with friends, the Hurricane season is always a threat for all Floridians. Last year, Hurricane Ian hit the peninsula. The rain and hard winds were not the only thing that Ian brought us. Hurricane Ian increased the risk of Vibrio Vulnificus as a serious waterborne infection. Vibrio vulnificus is a bacterium that normally lives in warm seawater and is part of a group of Vibrios that are called “halophilic” because they require salt for survival. Transmission with this bacterium can occur by eating raw shellfish and oysters. In addition, since it is naturally found in warm marine waters, patients with an open wound can be exposed to Vibrio vulnificus through direct contact with seawater. There is no evidence of person-to-person transmission of Vibrio vulnificus. How we can identify it in the lab? It is a Gram-negative non-spore forming rod-shape halophilic organism, and it is considered a reportable disease. Vibrio vulnificus infection is diagnosed by stool, wound, or blood cultures. It is also known as lactose-positive Vibrio that ends in the development of septicemia. Some of the virulence factors include a capsular polysaccharide, and different toxins mediating tissue invasiveness, motility expression, and regulation of biofilm formation for intestinal colonization. Patients with underlying conditions are at a high risk, with a 40-60 % mortality rate. Many people with V. vulnificus infections require intensive care or limb amputations, and 15-30% of infections are fatal (Centers for Science in the Public Interest, CSPI), 2020). Infection with Vibrio vulnificus is rare, but an increase in positive cases were seen with the arrival of Hurricane Ian. The Center for Disease Control and Prevention has developed a national surveillance system for V. vulnificus from the Gulf Coast states, where most cases occur. Conventional microbiology testing like gram staining, cultures and MALDI-ToF technologies can identify the microorganism. Molecular testing, including whole genome sequencing can help determine Vibrio spp. outbreaks, epidemiology, surveillance, route of transmission, and host susceptibility. Patient treatment should be initiated immediately because antibiotics can improve survival.
Cytomegalovirus (CMV) is a common virus for people of all ages; however, a healthy person’s immune system usually keeps the virus from causing illness. Once CMV is in a person’s body, it stays there for life and can reactivate. A person can also be re-infected with a different strain (variety) of the virus. Most people with CMV infection have no symptoms and aren’t aware that they have been infected. People with CMV may pass the virus in body fluids, such as saliva, urine, blood, tears, semen, and breast milk. CMV is spread from an infected person in the following ways: direct contact with saliva or urine (especially in babies and young children), through sexual contact, breast milk to nursing infants, and through transplanted organs and blood transfusions. Immunocompromised patients that become infected with CMV can have more serious symptoms affecting the eyes, lungs, liver, esophagus, stomach, and intestines. Babies born with CMV can have brain, liver, spleen, lung, and growth problems. The most common long-term health problem in babies born with congenital CMV infection is hearing loss, which may be detected soon after birth or may develop later in childhood. Blood tests can be used to detect the virus in adults, but the best sample for the diagnosis in newborns is saliva or urine. CMV is the most common infectious cause of birth defects in the United States. About 1 out of 200 babies are born with congenital CMV. One out of 5 babies with congenital CMV will have symptoms or long-term health problems, such as hearing loss. Antiviral medications (primarily valganciclovir) might improve hearing and developmental outcomes.
These emerging pathogens are considered a global public health problem due to the increase of transmission, lack of missed of diagnosis and rising mortality rates. Education, training, research, and awareness are the keys to decrease exposure with these emerging pathogens and to keep our communities safe.
Garam Choi, et al. (2022). Complex regulatory networks of virulence factors in Vibrio vulnificus. Trends in Microbiology, Vol.30(2