Ron Smith, MD

Malaria in the News

This Wright-stained blood smear photomicrograph depicted three, Plasmodium malariae trophozoites, one of which had assumed a band form morphology (arrow). In this case, the patient acquired this parasitic disease by having received contaminated blood during a transfusion.

Saturday, 19 August 2023

First locally-acquired case of malaria in over 40 years confirmed in Maryland

Tuesday, 27 June 2023

CDC: Florida, Texas Have First US Malaria Cases Since 2003

Thursday, 13 April 2023

Promising new malaria vaccine for kids approved in Ghana

DAKAR, Senegal — Ghana on Thursday became the first country to approve a new malaria vaccine for young children, one that officials hope will offer better protection against the disease that kills hundreds of thousands every year. Final results from late-stage trials have not yet been published, and the vaccine is under review at the World Health Organization. But preliminary results from early testing of the new vaccine, developed at the University of Oxford, have suggested the vaccine is far more effective than the only malaria vaccine now authorized for use by the WHO.

Wednesday, 2 November 2022

New Antibody Treatment Effective Against Malaria

Research in Africa found a one-time dose of an experimental drug protected adults against malaria for at least six months, the latest approach in the fight against the mosquito-borne disease. Malaria killed more than 620,000 people in 2020 and sickened 241 million, mainly children under 5 in Africa. The World Health Organization is rolling out the first authorized malaria vaccine for children, but it is about 30% effective and requires four doses.

Tuesday, 1 November 2022

Malaria Is on the Rise in Africa - Scientists Blame Invasive, Foreign Mosquito More Dangerous Than Native Ones

Scientists say an invasive mosquito species was likely responsible for a large malaria outbreak in Ethiopia earlier this year. The mosquito species, known as Anopheles stephensi, has mostly been seen in India and the Persian Gulf. In 2012, it was discovered in Djibouti and it has since been found in Sudan, Somalia, Yemen and Nigeria. The mosquitoes are suspected to be behind a recent rise in malaria in Djibouti, prompting the World Health Organization to try to stop the insects from spreading further in Africa.

Quick Overview

Monkeypox Clinical History and Features

Ryan, Edward, T. et al. Hunter’s Tropical Medicine and Emerging Infectious Diseases E-Book. Available from: Elsevier eBooks+, (10th Edition). Elsevier – OHCE, 2019.

Natural History and Pathogenesis

Monkeypox begins with infection of either the dermis (after transmission from infected animals) or the respiratory epithelium (after transmission from an infected person). The virus disseminates through the lymphatic system, resulting in primary viremia and systemic infection. A secondary viremia results in infection of the epithelium, producing skin and mucosal lesions. As a consequence of replication in mucosal surfaces the virus can be transmitted through oropharyngeal secretions to close contacts. The risk of transmission likely depends on the density of oropharyngeal lesions, the proximity and duration of contact, and virus survival, despite host immune responses. Monkeypox virus, like other poxviruses, has evolved mechanisms to evade host immune responses. Monkeypox virus is likely to be stable on fomites, and the number of virions required for infection is thought to be low based on potential similarities with variola virus. Strain differences may exist—monkeypox strains circulating in western Africa appear to be more attenuated and less transmissible than those in the Congo basin. 21

The incubation period from exposure to the onset of clinical symptoms and signs is 10 to 14 days. Patients are infectious during the first week of rash and should be isolated. 13 Most people infected with monkeypox virus are symptomatic, but sub-clinical infection can occur. Serologic studies of household contacts of acutely infected cases in the Democratic Republic of Congo suggest that approximately 28% of all monkeypox infections are sub-clinical. More recently, immunologic evidence of exposure to monkeypox virus was identified in several asymptomatic contacts of infected people in the United States.22,23
HIV and other conditions that suppress cell-mediated immunity may alter the natural history of disease. No data exist for monkeypox, but other poxvirus infections, specifically vaccinia and molluscum contagiosum viruses, are more severe in those who are infected with HIV.

Clinical Features

The clinical features of monkeypox resemble those of smallpox (variola) ( Table 32.2.3). Symptoms begin with a prodromal illness of fever and malaise lasting 1 to 3 days, followed by the characteristic rash. In contrast to smallpox, prominent sub-mandibular, cervical, post-auricular, axillary, or inguinal lymphadenopathy occurs in many infected persons 1 to 2 days before rash onset. Lymphadenopathy is not a typical feature of smallpox and can serve to clinically distinguish monkeypox from smallpox ( Fig. 32.2.2; see Table 32.2.3). As with smallpox, lesions develop concurrently and progress at a similar rate over 2 to 4 weeks, depending on the disease severity. The rash begins as small, 2- to 5-mm papules and progresses through vesicular, pustular, and crusted stages over 2 to 3 weeks ( Fig. 32.2.3). Like smallpox, it tends to be more severe on the head and extremities, including the palms and soles, and less intense on the trunk. The scabs slough off during recovery, leaving de-pigmented scars. Complications of monkeypox include secondary bacterial infection of the skin lesions, pneumonitis, and eye involvement. Death occurs during the second week of illness in approximately 10% of cases. Prior vaccination with vaccinia virus (smallpox vaccine) results in milder disease with fewer skin lesions, less lymphadenopathy, and significantly lower mortality. 24

TABLE 32.2.4 Centers for Disease Control and Prevention Case Definition for Monkeypox

Ryan, Edward, T. et al. Hunter's Tropical Medicine and Emerging Infectious Diseases E-Book. Available from: Elsevier eBooks+, (10th Edition). Elsevier - OHCE, 2019.
Incubation period
Prodrome period
Depth (diameter in mm)
Time to desquamation
Frequency of lesions on palms or soles of feet
Superficial to deep (4–6)
Centrifugal (mainly)
Homogeneous rash
Deep (4–6)
Homogeneous rash
Mild or none
Superficial (2–4)
Heterogeneous rash
Clinical Criteria
• Rash (macular, papular, vesicular, or pustular; generalized or localized; discrete or confluent)
• Fever (subjective or measured temperature of ≥99.3°F [≥37.4°C])
• Other signs and symptoms:
• Chills and/or sweats
• Headache
• Backache
• Lymphadenopathy
• Sore throat
• Cough
• Shortness of breath
Epidemiologic Criteria
• Exposure * to an exotic wild mammalian pet † obtained on or after April 15, 2003, with clinical signs of illness (e.g., conjunctivitis, respiratory symptoms, and/or rash)
• Exposure * to an exotic or wild mammalian pet † with or without clinical signs of illness that has been in contact with either a mammalian pet § or a human with monkeypox
• Exposure ¶ to a suspect, probable, or confirmed human case of monkeypox
Laboratory Criteria
• Isolation of monkeypox virus in culture
• Demonstration of monkeypox virus DNA by polymerase chain reaction testing of a clinical specimen
• Demonstration of virus morphologically consistent with an Orthopoxvirus by electron microscopy in the absence of exposure to another Orthopoxvirus
• Demonstration of presence of Orthopoxvirus in tissue using immunohistochemical testing methods in the absence of exposure to another Orthopoxvirus
Suspect Case
• Meets one of the epidemiologic criteria, AND
• Fever or unexplained rash, AND
• Two or more signs or symptoms with onset of first sign or symptoms less than 21 days after last exposure meeting epidemiologic criteria
Probable Case
• Meets one of the epidemiologic criteria, AND
• Fever, AND
• Vesicular-pustular rash with onset of first sign or symptom less than 21 days after last exposure meeting epidemiologic criteria, OR
• If rash is present but the type is not described, demonstrates elevated levels of IgM antibodies reactive with Orthopoxvirus between at least days 7–56 after rash onset
Confirmed Case
• Meets one of the laboratory criteria
• An alternative diagnosis can fully explain the illness, OR
• The case was reported on the basis of primary or secondary exposure to an exotic or wild mammalian pet or a human (see epidemiologic criteria) subsequently determined not to have monkeypox, provided other possible epidemiologic exposure criteria are not present, OR
• A case without a rash does not develop a rash within 10 days of onset of clinical symptoms consistent with monkeypox.
• The case is determined to be negative for non-variola generic Orthopoxvirus by polymerase chain reaction testing of a well-sampled rash lesion by the approved Laboratory Response Network (LRN) protocol, OR
• The case is determined to have undetectable levels of IgM antibody during the period 7–56 days after rash onset.