It is rare for symptoms to show up when histoplasmosis is present [7]. In the rare symptomatic cases, symptoms occur usually a few weeks after exposure. The acute phase of histoplasmosis is characterized by non-specific signs and symptoms including fever, cough, myalgia, chest pain, and malaise.

The chronic form of the disorder is more common in older individuals with an underlying pulmonary disease and might present with cough, weight loss, fever, and malaise.

Disseminated histoplasmosis in immunocompromised hosts can trigger organ failure and become life threatening if left untreated. This severe infection can lead to hepatosplenomegaly, lymphadenopathy, mucocutaneous lesions and central nervous system involvement.

Ocular histoplasmosis affects the eyes and can lead to damage in the retina.

Blood and sputum samples for cultures are necessary in order to diagnose histoplasmosis [8]. Urine analysis with polymerase chain reaction (PCR) or enzyme-linked immunosorbent assay (ELISA) can also be beneficial, particulary in immunocompromised hosts, to detect specific antigens. A serum antigen test may also be used, but this test can show false negative results four to six weeks after exposure.

Usually, this condition will resolve itself without any treatment as long as the affected individual is immunocompetent [9]. In some mild cases, symptomatic measures are indicated. In severe, chronic, or disseminated cases, treatment with antifungal medications like amphotericin B which is usually followed by oral itraconazole, is necessary.

Acute pulmonary histoplasmosis is considered to be asymptomatic 90 percent of cases [6]. The small percentage of affected individuals who do develop symptoms completely recover usually.

In rare instances, acute pericarditis and pleural effusion can develop. Chronic and disseminated forms have a poor prognosis and high mortality rate, if not treated timely.

Histoplasmosis is caused by the histoplasma capsulatum fungus [2]. The infectious spores are light and easily become airborne when disturbed. Histoplasma capsulatum is a thermally dimorphic fungus that is present in a mycelial form in the environment and grows into a yeast at body temperature. 

The fungus associated with histoplasmosis is found across the globe. There are certain places, like the Ohio River Valley and the lower Mississippi River area in the US, where the histoplasma capsulatum fungus is considered to be endemic [3]. Since the fungus is found in so many places, the occurrence of histoplasmosis is common especially in the US where 250,000 cases are reported every year. It is also prevalent in southern and eastern Africa, South America, Europe, and Asia. The disorder may occur at any age and there is no racial predilection.

There is a correlation with acidity and humidity levels of the soil as well as the activity level of local birds and bats. The fungus grows in soil that has been contaminated with bat or bird droppings and the microconida become airborne when the soil is disturbed.

The histoplasma capsulatum fungus grow in the mycelial form while in the saprobic state [4]. When the spores produced by this mycelial form along with mycelial fragments become airborne, they may be inhaled and deposited in alveoli. Under these favourable conditions, the spores can intracellularly be converted to the yeast form. 

The yeast reproduces within the first 15 to 18 hours after the phagocytosis by the macrophages occurs. The macrophages disseminate to various organs via lymphatic and blood circulation. After one to two weeks after the initial exposure, cellular immunity develops. The inflammatory response of the body may trigger the formation of calcified fibrinous granulomas within weeks to month after the initial infection.

Affected individuals with compromised immune systems may develop a progressive disseminated form of infection that can be life-threatening [5].

Since the fungus histoplasma capsulatum is found anywhere, it isn’t practical to decontaminate every area that is considered to be affected. For those who may be working in affected areas, like construction workers, protective masks should be worn [10].

Histoplasmosis is an infectious disease that predominantly affects the lungs but can involve other organ systems if it progresses to disseminated histoplasmosis. The disorder is caused by the histoplasma capsulatum fungus and can be fatal if left untreated. It is also known as Ohio Valley disease, Cave disease, Darling’s disease, and reticuloendotheliosis [1].

Histoplasma capsulatum that causes histoplasmosis can be found in soil that has been contaminated with bird or bat droppings. When this soil is disrupted by excavation or some type of construction, the fungus is aerated and the infectious properties are released. When the now infected air is breathed in, the fungus can settle in the lungs and cause histoplasmosis. The condtition is considered to be more common in people that have compromised immune systems.

Histoplasmosis is an infection that is caused by the fungus histoplasma capsulatum that is found in both bat and bird droppings. This fungus is present in the soil that the droppings contaminate. The spores become airborne when agitated and can settle in the lungs once inhaled.

There are usually no signs or symptoms associated with the condition and people are mostly unaware that they have the infection. Children and people with compromised immune systems, are prone to develop more severe forms and may show various symptoms including fever, cough, muscle pain, chest pain, and malaise. 

There are treatments that can be administered including antifungal medications, but in most cases, there is no need for medical treatment as the ailment usually clears up on its own.