The frequency and severity of this disease varies with the season and also with the locality. June and July have proved the most unhealthy months; the rainy season being then at its height. From December to March there is very little sickness. The natives state that some years are far more unhealthy than others, but this does not seem to depend upon the amount of rainfall. The most unhealthy stations are Wau, Meshra El Rek, and Tonj, all of which are built close to the river banks, whilst Rumbek and Deim Zubeir, which are some miles from a river, and watered from wells, are comparatively healthy. It is a noticeable fact that the natives never build villages near the river bank, but generally at least a mile inland; they also usually drink from wells. This is probably done to avoid mosquitoes, and therefore is a possible reason for the small amount of fever amongst them. Mosquitos cannot breed in shallow wells from which all the water is drawn several times daily. By selecting these positions for their villages they are also removed from the marsh, which is usually found on one or other bank of the river. Egyptians are more susceptible than Europeans, and the Sudanese from Khartoum more so than natives.
Varieties of fever.Although the ordinary periodic types of fever are met with, and easily combated by quinine, a malignant type is far from uncommon, and is a very serious trouble. The patient may have two or three distinct attacks of fever in one day, and often on two or three consecutive days, leaving him weak and unfit for duty. Vomiting is a common accompaniment, and sometimes continues for two days. The stomach refuses food or medicine, and quinine has to be injected subcutaneously. Drugs, however, seem to have little effect on the course of the fever. The after effects met with are anæmia, rheumatism, neuralgia, and dyspepsia. The most serious complication, however, is “blackwater fever,” which is a hæmoglobinuria, occurring in a patient saturated with malaria. The red-blood corpuscles are destroyed by the action of the malarial parasite, and the hæmoglobin thus set free is passed in the urine, giving it its characteristic port wine colour. The patient becomes terribly weak, has acute pain over the stomach, vomits frequently, and cannot retain any nourishment, the heart becomes very feeble, and death only too often follows. At present there have been as far as is known, since 1900, about eight cases, with only two recoveries; it does not appear to attack natives at all.
Guinea worm.Guinea worm is common amongst the natives and Sudanese. It has been met with all over the country, from Meshra El Rek to the Nyam Nyam country. It appears in June and July, and is often the cause of ankylosis of the joints. From observations made in 1901-02 the period of incubation would appear to be a long one—probably 10 or 12 months. At least one European has developed it.
Boils.Boils are common and appear in epidemic form, chiefly attacking the hands.
Dysentery.Dysentery in its true form has not been met with. The water supply at all stations is good.
Small-pox.Small-pox occurs occasionally amongst the natives and carries off hundreds. An outbreak occurred amongst Tembura’s Nyam Nyams in the winter of 1903-04.
Phthisis.Phthisis in all its forms is common, and is believed to be responsible for a large percentage of the mortality amongst natives. September, October and November are the months in which it is most prevalent.
Night blindness is common.
Beyond mention of the great frequency of hydrocele and hernia amongst the natives, there is nothing else that calls for special remark.
Mosquitos.Mosquitos are not very numerous on the dry plateaux of the table-land and the lower steppes during the dry season, but abound during the rainy season near the rivers. Near the sudd, and on it, they are always to be met with, but not in any quantities away from the rivers. At least two out of six specimens sent home were found to belong to malaria-bearing species.