Most deaths are in children <5 years of age in sub-Saharan Africa.

Most severe infections are caused by Plasmodium falciparum transmitted by Anopheles mosquito.

Some signs of severe malaria include lactic acidosis, severe anemia, respiratory distress, hypoglycemia, impaired consciousness, and prostration.

The level of parasitemia may not reflect true parasite burden, but >5% of parasitized red blood cells suggests severe disease in nonimmune individuals.

Cerebral malaria carries a high mortality rate and should be treated with parenteral antimalarials.

Severe malaria requires intensive care monitoring and antimicrobial treatment with agents active against P. falciparum.

ECG monitoring is necessary during quinidine or quinine therapy to assess for cardiac toxicity, including widening of the QRS and QT_C prolongation.

Attention to glucose level is critical, as hypoglycemia frequently complicates severe malaria and may contribute significantly to morbidity and mortality.

Typhoid fever is a bacterial infection spread by the fecal-oral route without any nonhuman reservoirs.

Disease is prevalent in most tropical developing countries but highest on the Indian subcontinent.

Diarrhea is more common among children but does not occur in most cases.

Death occurs in cases of complicated disease: gastrointestinal bleeding, perforation, or typhoid encephalopathy.

Diagnosis can be difficult, as blood cultures have a low sensitivity. Bone marrow culture may have a higher yield, especially after the initiation of therapy.

Fluoroquinolone-resistant infections are increasing in Asia and make the treatment of the disease more complicated.

Empiric therapy should be IV ceftriaxone until susceptibility of the organism is known.

Relapse is common.

Infection with Trypanosoma cruzi causes Chagas disease.

Acute infection is usually nonspecific, but subclinical cardiac involvement may occur.

After acute infection, untreated patients enter an indeterminate phase.

Ten to fifteen percent of patients in the indeterminate phase go on to develop the chronic sequelae of infection: cardiomyopathy and megaviscera.

Treatment during the acute phase of illness prevents progression to chronic end-organ damage.

Human African Trypanosomiasis is caused by T. bruceirhodiense (East) or T. bruceigambiense (West) and results in sleeping sickness.

In children, developmental delay may be more prominent than somnolence.

Acute and late-stage infections are treated differently. The presence of >5 cells/mm³ in the cerebrospinal fluid defines late-stage infection.

The disease is fatal if untreated.

Infection with Leptospira species causes a chronic lowgrade infection in animal hosts who subsequently excrete the organisms into the environment, where they can survive for prolonged periods of time.

In urban environments, small rodents are important hosts.

The majority of leptospirosis infections are asymptomatic or mild.

Icteric leptospirosis (Weil disease) is characterized by renal failure, icterus, and hemorrhagic manifestations.

Treatment with penicillin, ceftriaxone, or doxycycline is recommended for symptomatic disease, although the role of therapy has not been definitively established.

Mortality rates have been reported to be 5%-25% in hospitalized patients.

Hemorrhagic fever with renal syndrome (HFRS) can be seen with other hantaviruses in Europe and Asia.

Infection with American hantaviruses can result in hantavirus pulmonary syndrome (HPS).

Rodents are the hosts for disease and transmit disease to humans.