Tropical Medicine 9: Pulmonary Manifestations
Many things may cause respiratory symptoms (cough, hemoptysis, dyspnea), ranging from viral infections, to irritant and allergic causes (including asthma and COPD), to malignancies. The focus of this chapter are those etiologies not commonly encountered outside of the developing world, and not discussed in other portals of this Section.
Tuberculosis
This is one
of the leading causes of death from infectious disease worldwide. The
responsible organism, a mycobacterium, is transmitted
person--to--person, via the respiratory
route. Inspired organisms are phagocytised, but survive
intracellularly and are spread throughout
the
body. Approximately 10% of
patients infected progress to disease.1
Pulmonary tuberculosis causes night sweats, chronic fevers, significant weight loss, and hemoptysis. Large cavitating lesions may be present, and are more common in the apical regions of the lungs.
Extrapulmonary tuberculosis presents a variety of clinical pictures, including pericarditis, meningitis, lymphadenitis, cystitis, osteomyelitis, and a host of other inflammatory manifestations.
Diagnosis is often initially suspected by a positive Mantoux test, supported by radiological exam, and confirmed by identification of acid--fast bacteria in the sputum, body fluid, or tissue sample.
The foundation of treatment is full compliance and a multidrug regimen. This is essential to decrease the morbidity, mortality, and spread of the infection as well as to prevent development of resistant organisms. This may require “directly observed therapy.” Specific regimens may be suggested by the local health department or CDC—depending upon symptoms and findings on Mantoux and x--ray—and may include combinations of the following agents:
AntiTubercular Medications
| Agent | Dose (mg/kg) |
| Isoniazid | 5 mg/kg 4 times per day, or 10 mg/kg 3 times per week or 15 mg/kg weekly |
| Rifampin | 10 mg/kg 4 times per day or 3 times weekly or 2 times weekly |
| Pyrazinamide | 25 mg/kg 4 times per day or 35 mg/kg 3 times weekly or 50 mg/kg twice weekly |
| Streptomycin | 15 mg/kg 4 times per day, or 3 times weekly, or twice weekly |
| Ethambutol | 15 mg/kg 4 times per day, or 30 mg/kg 3 times weekly, or 45 mg/kg twice weekly |
| Thioacetazone | 2.5 mg/kg 4 times per day; less frequent dosing is not indicated |
Paragonimiasis
The lung
fluke is acquired by eating undercooked crabs and the like, which
contain the metacercariae. They migrate to the peritoneum, mature, and
tunnel to
the lungs where they cause inflammation, bleeding, and necrosis. This
presents
with a cough producing brownish sputum, in which the eggs may be seen
on
microscopy, which
confirms diagnosis. Treatment is praziquantel 25 mg/kg 3 times daily
for 2 to 3 days. Occasionally, aberrant migration may result in the
adult worms winding
up all sorts of places, causing damage there (eg, intracranial, solid
abdominal organs, or virtually any other anatomical location).
Melioidosis
Burkholderia pseudomallei,
ordinarily a soil saprophytic organism, is an unusual
cause of pneumonia. If inoculated or inhaled, it may remain within the
macrophages for years before causing disease. Most infections are
asymptomatic, but pneumonia, abscess, and sepsis may result. Mortality
rate is as high as 50% in septic cases.1 Disease is more common in individuals with immunosuppressed
states, such as diabetes, steroid treatment, and malignancy.
Diagnosis is by culture or serology. Treatment is difficult, with ceftazidime IV for a minimum of 10 days (often longer) followed by amoxicillin clavulanate (Augmentin) for 20 weeks to prevent relapse.
Geohelminths
Many parasitic worms, such as
Ascaris, have a transpulmonary stage
in their life. This can result in a productive cough, asthma, and other pulmonary
symptoms. (Vol III—TM4 Gastrointestinal and Abdominal Manifestations)
Tropical Pulmonary Eosinophilia
This is an asthma-like disease caused by a reaction to the lymphatic filariae
(See Vol III—TM10 Urogenital Manifestations for greater detail.)
Diagnosis is
by serology or identification of the
microfilariae in a nighttime blood smear. Treatment is ivermectin. (Vol III—TM13 Antiparasitic Primer).
References
-
Gill GV, Beeching NJ. Lecture notes in tropical medicine, 5th ed. Malden, MA: Blackwell Science, 2004.